Fabricated reinforced concrete-steel structure foundation pit supporting system and dismantling method

Abstract

The invention relates to the field of constructional engineering, and discloses a fabricated reinforced concrete-steel structure foundation pit supporting system. The system is structurally characterized in that rope saw cutting holes are pre-formed in a top beam and a waist beam, and an inner supporting system is composed of a main support composed of steel-concrete beam sections, a steel structure auxiliary support, a jack adjusting system and a steel latticed column; the invention further provides a dismantling method of the fabricated reinforced concrete-steel structure foundation pit supporting system convenient to dismantle, that is, main tools such as a crane and a rope saw are used for dismantling from the bottommost layer to the upper layer step by step; according to the method, the dismantling speed is high, noise pollution and dust pollution are little, the dismantling cost is low, the dismantled reinforced concrete beam sections, the dismantled steel structure auxiliary supports and the like can be recycled and reused, the method is successful practice of circular economy and green dismantling in the field of foundation pit supports, and good economic benefits and social benefits are achieved.

Description

Technical Field

[0001] The invention relates to the field of construction engineering, and in particular to an assembled steel-concrete-steel structure foundation pit support system and a dismantling method. Background Art

[0002] In large-scale foundation pit projects, reinforced concrete foundation pit support is an important measure to ensure that the foundation pit does not deform or collapse. In engineering, large-scale foundation pits mostly use underground continuous walls or support piles with cast-in-place reinforced concrete internal supports to achieve the support purpose. However, cast-in-place reinforced concrete internal supports have many disadvantages: 1. The construction process of reinforced concrete internal support includes steps such as steel bar binding, formwork installation, concrete pouring and maintenance. These steps require a long construction time, affecting the progress of the project and increasing the project cost; 2. It is difficult to dismantle reinforced concrete internal supports after the project is completed. The dismantling process requires a lot of mechanical equipment and manual operations, which is time-consuming and costly. At the same time, the dismantling process will generate a lot of construction waste, which needs to be processed and transported, increasing construction costs and environmental pressures. 3. Whether it is mechanical demolition or blasting demolition, the noise, dust and construction waste generated by the removal of reinforced concrete internal supports have a great impact on the surrounding environment. Especially when constructing in the central area of ​​the city, additional environmental protection measures need to be taken, which increases the cost of demolition construction and the difficulty of management; 4. Most of the steel and concrete waste after demolition has low reuse value and can only be treated as construction waste, which wastes resources. In order to overcome the above shortcomings of the cast-in-place reinforced concrete foundation pit support system, it is urgent to develop new foundation pit support technology.

[0003] In order to overcome the shortcomings of cast-in-place reinforced concrete internal supports, Chinese patent publication number: CN118793069A discloses an easy-to-dismantle assembled reinforced concrete foundation pit support system and construction method. All parts of the internal support system are completely made of prefabricated concrete components regardless of the stress size. Not only can they not be used in conjunction with steel support components, but the heavy dead weight of the internal support also causes inconvenience in construction.

[0004] In order to overcome the above problems, a new type of prefabricated steel-concrete-steel structure foundation pit support system needs to be developed for foundation pits with large ground stress. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art and provide an assembled steel-concrete-steel structure foundation pit support system, including a crown beam, a waist beam, support piles and an internal support system, wherein the internal support system is composed of a plurality of main supports composed of a plurality of prefabricated steel-concrete beam sections, a plurality of steel structure auxiliary supports, a plurality of steel lattice columns and an adjustment system; the steel-concrete beam sections are standard parts of the same structure and size; The surface of the steel-concrete beam section is provided with a beam sleeve, and a rectangular concrete is arranged inside, and a cable hole is arranged in the rectangular reinforced concrete; longitudinal reinforcing bar holes, vertical screw holes, and transverse screw holes are arranged at both ends of the steel-concrete beam section, and the longitudinal reinforcing bar holes, vertical screw holes, transverse screw holes, and cable holes do not intersect each other; The crown beam and waist beam are provided with a plurality of corbels, each of which is provided with a cap; the crown beam and waist beam are respectively provided with an L-shaped embedded hole and an I-shaped embedded hole for rope saw cutting; Each of the main supports is formed by axially connecting a plurality of steel-concrete beam sections, and the connection point between two steel-concrete beam sections is an axial node; a plurality of steel structure auxiliary supports are connected between adjacent main supports, and the connection method is that the two ends of the steel structure auxiliary supports are connected to one side of the two axial nodes of the adjacent main supports; one side of the axial node of some main supports close to the foundation pit wall is connected to a steel structure auxiliary support, and the other end of the steel structure auxiliary support is connected to the side of the crown beam or the waist beam, and the steel structure auxiliary support here is a steel structure eight-shaped beam; The structure of the axial node is as follows: the end faces of the two steel-concrete beam sections are closely fitted, and a connecting steel plate is provided at each span of the upper and lower surfaces of the fitting, and a No. 6 hole is opened on the connecting steel plate, and the longitudinal reinforcing bar holes on the end faces of the two steel-concrete beam sections are aligned one by one and inserted with round steel; The main support described above forms a row of main supports or two main supports are connected to form a row of main supports through an adjustment system, and both ends of each row of main supports are placed on the bearing platform; The main support is installed on the steel lattice column, and the contact position between the main support and the steel lattice column is staggered from the axial node; a tray is provided on the steel lattice column, and the main support is placed on the tray, and one side of the steel-concrete beam section in the main support is close to the lattice column. One end of the hoop is welded on the tray, and the hoop embraces the main support, and the other end is welded to the steel lattice column to fix the main support.

[0006] Furthermore, a cable adjuster is provided below the axial node, and the cable adjuster is composed of an adjuster base plate, an adjusting screw, an adjuster support rod, a web, a left-handed nut, a fixing piece, a right-handed nut, and a pin shaft; a No. 2 hole is provided on the adjusting base plate; two fixing pieces are welded on the web and the adjusting base plate; each fixing piece has two pin shafts, and two adjuster support rods are connected to the two pin shafts, and the other ends of the two adjuster support rods are respectively connected to a right-handed nut and a left-handed nut through the pin shafts; a handle is provided at the end of the adjusting screw, and a There are two groups of positive and negative threads, each group of positive and negative threads includes a right-hand thread and a left-hand thread; each group of positive and negative threads is equipped with a right-hand nut and a left-hand nut; the vertical screw hole at the axial node, the No. 6 hole on the two connecting steel plates and the No. 2 hole on the inclined cable adjuster are coaxial, and vertical tension screws are passed through, and nuts are provided at both ends of the vertical tension screws; the inclined cable is inserted into the inclined cable hole, and the inclined cable extends from the inclined cable hole of one steel-concrete beam section and extends from the inclined cable hole of another adjacent steel-concrete beam section; the two ends of the inclined cable are fixed with anchor heads, and the middle part is placed on the web of the inclined cable adjuster.

[0007] Furthermore, the steel structure auxiliary support is formed by welding frame members and end plates; the frame members are I-beams, steel pipes or H-shaped steels; the end plates are steel plates, on which No. 1 holes for connection are provided, and the No. 1 holes have the same diameter and spacing as the transverse screw holes.

[0008] Furthermore, after the No. 1 hole of one end plate of the steel structure S-beam is aligned one by one with the transverse screw hole at the axial node position on the steel-concrete beam section close to the foundation pit wall, a transverse tension screw is inserted, and the two ends of the transverse tension screw are fixed with nuts; the other end plate of the steel structure S-beam is fixed to the crown beam or waist beam with bolts.

[0009] Further, there are three ways to connect one side of the axial node with the steel structure auxiliary support. The first one is: one side of the axial node is connected to a steel structure auxiliary support, and the end plate is connected to the axial node across the seam, that is, the No. 1 hole of the end plate is respectively connected to the transverse screw hole on one side of the end of the two steel-concrete beam sections connected at the axial node, and fixed with transverse tension screws and nuts; The second type is: one side of the axial node is connected to two steel structure auxiliary supports, a side connection steel plate is arranged on one side of the axial node, the side connection steel plate has four rows of No. 5 holes, the span seams correspond one-to-one with the two rows of transverse screw holes on the sides of the two steel-concrete beam sections at the axial node, and also correspond one-to-one with the No. 1 holes on the end plates of the two steel structure auxiliary supports, and after the transverse tension screws pass through the coaxial No. 1 holes, No. 5 holes and transverse screw holes, both ends are tightened with nuts; The third type is: there is no auxiliary support connection on one side of the axial node, the axial node is installed on this side with a connecting steel plate, and the transverse tension screw is passed through the No. 5 hole and the transverse screw hole, and the two ends of the transverse tension screw are fixed with nuts.

[0010] Furthermore, angle steels are welded at the four corners where the connecting steel plate is connected to the side connecting steel plate or at the four corners where the connecting steel plate is connected to the end plate of the auxiliary support.

[0011] Furthermore, the adjustment system is divided into a mid-beam adjustment system and a beam end adjustment system; the mid-beam adjustment system includes a force-retaining steel structure and a jack placed on the force-retaining steel structure, and the beam end adjustment system includes a force-retaining head, a gasket and a jack arranged on the pedestal; the force-retaining steel structure is composed of part A, part B, steel sheets, insert rings and insert plates; part A is composed of two long steel plates and a steel partition plate vertically welded between the two long steel plates, wherein a connecting plate is welded on one side of a long steel plate, and the connecting plate has a number three hole; a force-retaining box is welded on one side of the other long steel plate, and the force-retaining box is formed by welding steel plates; part B is composed of two long steel plates and a steel partition plate vertically welded between the two long steel plates, wherein a connecting plate is welded on one side of a long steel plate, and the connecting plate has a number four hole, and a jack is welded on one side of the other long steel plate Top support and protruding steel plate, the jack support is formed by welding a semicircular steel plate on a long steel plate; the height of the long steel plate and several steel partitions is the same as the cross-sectional height of the steel-concrete beam section; the connecting plate is a group of two, and the spacing between the two connecting plates is the same as the cross-sectional width of the steel-concrete beam section; the plug ring is welded on the side of the force box at both ends of part A and the side of the two end heads of part B; the arrangement and aperture of the No. 3 hole and the No. 4 hole are the same as the transverse screw holes of the steel-concrete beam section, and the width of the steel sheet is the same as the width of the force box; the force box of part A is placed on the protruding steel plate of part B, and the connection between part A and part B is achieved by inserting the plug plate into the plug ring; the connection between the force steel structure and the main support is achieved by making the No. 4 hole on the connecting plate correspond one by one to the transverse screw hole of the main support end, inserting the transverse tension screw and tightening it with a nut.

[0012] Furthermore, there are two types of the pedestals, one of which is composed of embedded steel plates, embedded steel bars, a pedestal bottom plate, and pedestal side plates; the other of which is composed of embedded steel plates, embedded steel bars, a pedestal bottom plate, a pedestal side plates, a jack wooden support, a force-retaining head, and a gasket; the force-retaining head is formed by welding an I-beam and a steel plate, the steel plate size of the force-retaining head is the same as the cross-sectional size of the steel-concrete beam section, the embedded steel plates are all arranged at the corbels, and embedded steel bars are welded to one side of the embedded steel plates.

[0013] Furthermore, the L-shaped pre-buried holes and the I-shaped pre-buried holes are respectively preset in the crown beam and the waist beam every -m; The L-shaped embedded hole is formed by embedding an L-shaped PVC tube in the crown beam. The L-shaped PVC tube has two openings at both ends, one end is opened on the upper surface of the crown beam, and the other end is opened on the side of the crown beam. The embedded position of the L-shaped PVC tube is staggered with the position of the corbel. The I-shaped embedded hole is formed by embedding an I-shaped PVC pipe in the waist beam. Both ends of the I-shaped PVC pipe are open, one end is located on the top surface of the waist beam, and the other end is located on the bottom surface of the waist beam. The I-shaped PVC pipe is embedded on one side of the waist beam close to the supporting pile, and the embedded position of the I-shaped PVC pipe is staggered with the position of the corbel.

[0014] Furthermore, the method for dismantling the prefabricated steel-concrete-steel structure foundation pit support system is characterized by comprising the following steps: 1) Prepare the wire saw cutting machine, support frame, crane, forklift and other machines and tools, and arrange the location and access channels of the machines and tools; 2) After the foundation slab is constructed, wait until it reaches 80% of the design strength, then construct the floor slab below the lowest support. After the support is replaced, prepare to remove the lowest support; 3) Jack extension: the jack on the beam adjustment system extends the A part of the force-retaining steel structure, and the jack on the beam end adjustment system extends the force-retaining head; remove the gasket and steel sheet, and the jack is depressurized, and the jack, force-retaining head and jack wooden support are removed; 4) Use a cutting machine to cut the angle steel at the axial node of the main support; remove the steel structure auxiliary support of the lowest support: after setting up the support frame under the steel structure auxiliary support, loosen the nut, remove the transverse tension screws and bolts, remove the side connecting steel plate, and then use a forklift or crane to transport the steel structure auxiliary support out of the foundation pit; 5) Dismantle the steel-concrete beam sections of all the main supports of the lowest support row by row: start dismantling each row of main supports from the pedestal with jacks or from the steel structure, set up a support frame under the steel-concrete beam section to be dismantled, and use a cutting machine to cut the pedestal and clamps; remove the transverse tension screws and nuts connecting the steel structure and the steel-concrete beam section, pull out the plug plate in the plug ring, and dismantle the A and B parts of the steel structure; use a forklift and a crane to transport the dismantled A and B parts of the steel structure out of the foundation pit; loosen the anchor heads at both ends of the inclined cable, pull out the inclined cable and vertical tension screws at the axial node of the main support, and remove the connecting steel plate and inclined cable adjuster; use a forklift to pull out the steel-concrete beam section one by one from the axial node along the axial direction, and then pull out the connecting round steel; use a crane to transport the dismantled steel-concrete beam section out of the foundation pit; 6) Set up a support frame under the waist beam of the lowest support and its upper corbel; 7) Use a rope saw to cut the corbels; after clearing the I-shaped pre-buried hole of the waist beam of the lowest support, insert the rope saw chain into the I-shaped pre-buried hole, turn on the rope saw cutting machine, and cut the waist beam; the cut waist beam section and corbels are transported out of the foundation pit by forklifts and cranes; 8) Repeat steps 2) to 7) to complete the removal of all non-first support; 9) Construct the floor slab below the first support, and after replacing the support, prepare to remove the first support; 10) Repeat steps 3), 4), and 5) to complete the removal of the main support, steel structure auxiliary support, and adjustment system of the first internal support system; 11) Set up a support frame under the corbel of the crown beam of the first support; 12) Use a rope saw to cut the corbels; after clearing the L-shaped pre-buried hole of the crown beam of the first support, insert the rope saw chain into the L-shaped pre-buried hole, turn on the rope saw cutting machine, cut the crown beam, and transport the cut crown beam section and corbels out of the foundation pit with a forklift or crane; 13) Use a cutting machine to cut the steel lattice columns, and the cut steel lattice columns are transported out of the foundation pit by a crane.

[0015] Compared with the prior art, this application has the following beneficial effects: The present invention provides an assembled steel-concrete-steel structure foundation pit support system, which adopts steel-concrete beam sections in parts with greater stress and uses steel structure auxiliary supports in parts with less stress. The structure of the support system in the foundation pit is stable and reliable; the new system can give full play to the advantages of the two materials, greatly reducing the difficulty of lifting, transportation and installation of the original pure assembled reinforced concrete support, improving the convenience of construction and reducing costs; the new system can provide flexible and diverse planar support structures, which can adapt to more application scenarios.

[0016] The present invention provides an assembled steel-concrete-steel structure foundation pit support system, the nodes of which are connected by screw rods and steel plates, and components such as inclined cables, side connection steel plates, steel structure auxiliary supports and angle steels are installed. The internal support is easier to dismantle, and the noise pollution during dismantling is small and there is no dust pollution.

[0017] The present invention provides a method for dismantling an assembled steel-concrete-steel structure foundation pit support system, which dismantles the inner support from bottom to top, and completely dismantles the steel-concrete beam section and the steel structure auxiliary support. The dismantled steel-concrete beam section, the steel structure auxiliary support and the connectors of the node connection can be recycled and reused multiple times, which greatly reduces the cost of a single foundation pit support.

[0018] The present invention provides a steel-concrete beam section, which consists of a rectangular reinforced concrete and a beam sleeve sleeved on the rectangular reinforced concrete; the beam sleeve greatly reduces the damage rate of the steel-concrete beam section during the dismantling process, increases the number of cycles of the steel-concrete beam section, and reduces the cost of a single foundation pit support.

[0019] The present invention adopts a full-life design concept and pre-buries holes for rope saw cutting in the crown beam and waist beam of the foundation pit. During the cutting and dismantling process of the crown beam and waist beam of the foundation pit, drilling-free operation is achieved, which speeds up the dismantling of the crown beam and waist beam of the foundation pit, saves dismantling costs, reduces carbon emissions, and implements the concept of green development. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the first support plane of the prefabricated steel-concrete-steel structure foundation pit support system.

[0021] Figure 2 It is a schematic diagram of the non-first support plane of the prefabricated steel-concrete-steel structure foundation pit support system.

[0022] Figure 3 It is a schematic diagram of the overall structure of the steel-concrete beam section.

[0023] Figure 4 It is a schematic diagram of the overall structure of a steel structure S-beam whose frame is an I-beam.

[0024] Figure 5 It is a schematic diagram of the overall structure of a steel structure support with steel pipes as the frame.

[0025] Figure 6 It is a schematic diagram of the connection between the steel-concrete beam section and the steel structure auxiliary support whose frame is a steel pipe.

[0026] Figure 7 It is a schematic diagram of the diagonal steel bar adjuster.

[0027] Figure 8 It is a schematic diagram of the Baoli steel structure.

[0028] Fig. 9 This is a schematic diagram of the application of Baoli steel structure.

[0029] Fig.10 It is a schematic diagram of the steel-concrete beam sections placed on the pallet.

[0030] Fig.11 It is a schematic diagram of the edge of the first angle brace of the prefabricated steel-concrete-steel structure foundation pit support system.

[0031] Fig.12 It is a schematic diagram of the first supporting edge of the prefabricated steel-concrete-steel structure foundation pit support system.

[0032] Fig.13 This is a schematic diagram of the pedestal used for the angle brace of the first support.

[0033] Fig.14 This is a schematic diagram of a supporting platform that is not the first support.

[0034] Fig.15This is a schematic diagram of a cap used for corner bracing that is not the first support.

[0035] Fig.16 It is a schematic diagram of the structure of the connecting steel plate and the side connecting steel plate.

[0036] Fig.17 It is a schematic diagram of the structure of the L-shaped embedded hole of the crown beam.

[0037] Fig.18 It is a schematic diagram of the structure of the I-shaped embedded holes in the waist beam.

[0038] Fig.19 It is a schematic diagram of the steel-concrete beam section and the steel structure auxiliary support whose frame is a steel pipe, which is vertically arranged and connected and then welded with angle steel.

[0039] Fig. 20 It is a schematic diagram of the oblique connection between the steel-concrete beam section and the steel structure auxiliary support whose frame is I-beam.

[0040] Fig.21 It is a schematic diagram of the oblique arrangement and connection between the steel-concrete beam section and the steel structure auxiliary support whose frame is steel pipe.

[0041] Fig. 22 It is a schematic diagram of the internal support plane layout of Example 1.

[0042] Fig.23 It is a schematic diagram of the internal support plane layout of Example 2.

[0043] Fig.24 It is a schematic diagram of the internal support plane layout of Example 3.

[0044] In the figure: 1-steel-concrete beam section; 101-beam sleeve; 102-rectangular reinforced concrete; 103-longitudinal reinforcement hole; 104-vertical screw hole; 105-transverse screw hole; 106-oblique cable hole; 2-steel structure auxiliary support; 201-frame; 202-end plate; 202-1-No. 1 hole; 3-support pile; 4-jack; 5-security steel structure; 501-A part 501; 501-1-No. 3 hole; 50 1-2-force box; 502-B part; 502-1-No. 4 hole; 502-2-jack support; 502-3 protruding steel plate; 503-steel sheet; 504-insert ring; 505-insert plate; 6-round steel; 7-vertical tension screw; 8-transverse tension screw; 9-oblique cable; 10-nut; 11-side connecting steel plate; 1101-No. 5 hole; 12-connecting steel plate; 1201-No. 6 hole; 1301, adjustment 1301-1, No. 2 hole; 1302, adjusting screw; 1302-1, right-hand thread; 1302-2, left-hand thread; 1302-3, handle; 1303, adjusting support rod; 1304, web bar; 1305, left-hand nut; 1306, fastener; 1307, right-hand nut; 1308, pin; 14- bearing platform; 1401- embedded steel plate; 1402- embedded steel bar; 1 403-base plate; 1404-base side plate; 1405-jack wooden support; 1406-bolster head; 1407-gasket; 15-tray; 16-steel lattice column; 17-crown beam; 1701-L-shaped embedded hole; 18-waist beam; 1801-I-shaped embedded hole; 19-corbel; 20-hoop; 21-bolt; 22, L-shaped PVC pipe; 23, I-shaped PVC pipe; 24-angle steel; 25-anchor head. DETAILED DESCRIPTION

[0045] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. The steel-concrete beam section 1 is fully called an assembled foundation pit support beam section that can be matched with a steel support.

[0046] Depend on Figure 1-Figure 24 Provided is an assembled steel-concrete-steel structure foundation pit support system, comprising a crown beam 17, a waist beam 18, support piles 3 and an internal support system, wherein the internal support system is composed of a plurality of main supports composed of a plurality of prefabricated steel-concrete beam sections 1, a plurality of steel structure auxiliary supports 2, a plurality of steel lattice columns 16 and an adjustment system; the steel-concrete beam sections 1 are standard parts of the same structure and size; The surface of the steel-concrete beam section 1 is provided with a beam sleeve 101, and a rectangular concrete 102 is arranged inside. A cable hole 106 is arranged inside the rectangular reinforced concrete 102; longitudinal reinforcing bar holes 103, vertical screw holes 104, and transverse screw holes 105 are arranged at both ends of the steel-concrete beam section 1, and the longitudinal reinforcing bar holes 103, the vertical screw holes 104, the transverse screw holes 105, and the cable holes 106 do not intersect each other; A plurality of corbels 19 are provided on the crown beam 17 and the waist beam 18, and a cap 14 is provided on each of the corbels 19; an L-shaped pre-buried hole 1701 and an I-shaped pre-buried hole 1801 for rope saw cutting are provided in the crown beam 17 and the waist beam 18 respectively; Each main support is formed by axially connecting a plurality of steel-concrete beam sections 1, and the connection point between two steel-concrete beam sections 1 is an axial node; a plurality of steel structure auxiliary supports 2 are connected between adjacent main supports, and the connection method is that the two ends of the steel structure auxiliary supports 2 are connected to one side of the two axial nodes of the adjacent main supports; one side of the axial node of some main supports close to the foundation pit wall is connected to a steel structure auxiliary support 2, and the other end of this steel structure auxiliary support 2 is connected to the side of the crown beam 17 or the waist beam 18, and the steel structure auxiliary support 2 here is a steel structure eight-shaped beam; The structure of the axial node is as follows: the end faces of the two steel-concrete beam sections 1 are closely fitted, and a connecting steel plate 12 is provided on each span of the upper and lower surfaces of the fitting, and a No. 6 hole 1201 is opened on the connecting steel plate 12, and the longitudinal reinforcing bar holes 103 on the end faces of the two steel-concrete beam sections 1 are aligned one by one and inserted with round steel 6; One main support constitutes a row of main supports or two main supports are connected to form a row of main supports through an adjustment system, and both ends of each row of main supports are placed on the cap 14; The main support is installed on the steel lattice column 16, and the contact position between the main support and the steel lattice column 16 is staggered from the axial node; a tray 15 is provided on the steel lattice column 16, and the main support is placed on the tray 15, and one side of the steel-concrete beam section 1 in the main support is close to the lattice column 16, and one end of a hoop 20 is welded on the tray 15, and the hoop 20 embraces the main support, and the other end is welded to the steel lattice column 16 to fix the main support.

[0047] Preferably, a cable adjuster 13 is provided below the axial node, and the cable adjuster 13 is composed of an adjuster base plate 1301, an adjusting screw 1302, an adjuster support rod 1303, a web 1304, a left-handed nut 1305, a fixing piece 1306, a right-handed nut 1307, and a pin 1308; a No. 2 hole 1301-1 is provided on the adjusting base plate 1301; two fixing pieces 1306 are welded on the web 1304 and the adjusting base plate 1301; each fixing piece 1306 has two pins 1308, and two adjuster support rods 1303 are connected to the two pins 1308, and the other ends of the two adjuster support rods 1303 are respectively connected to the right-handed nut 1307 and the left-handed nut 1305 through the pins 1308; a handle 1301 is provided at the end of the adjusting screw 1302 02-3, two groups of positive and negative threads are arranged on the adjusting screw 1302, and each group of positive and negative threads includes a right-handed thread 1302-1 and a left-handed thread 1302-2; each group of positive and negative threads is equipped with a right-handed nut 1307 and a left-handed nut 1305; the vertical screw hole 104 at the axial node, the No. 6 hole 1201 on the two connecting steel plates 12 and the No. 2 hole 1301-1 on the inclined cable adjuster 13 are coaxial, and are penetrated by the vertical tension screw 7, and the two ends of the vertical tension screw 7 are provided with nuts 10; the inclined cable 9 is inserted into the inclined cable hole 106, and the inclined cable 9 extends from the inclined cable hole 106 of one steel-concrete beam section 1, and extends from the inclined cable hole 106 of another adjacent steel-concrete beam section 1; the two ends of the inclined cable 9 are fixed with anchor heads 25, and the middle part is placed on the web 1304 of the inclined cable adjuster 13.

[0048] Preferably, the steel structure auxiliary support 2 is formed by welding a frame 201 and an end plate 202; the frame 201 is an I-beam or a steel pipe or an H-beam; the end plate 202 is a steel plate, on which a No. 1 hole (202-1) for connection is provided, and the No. 1 hole 202-1 has the same diameter and spacing as the transverse screw hole 105.

[0049] Preferably, the No. 1 hole 202-1 of one end plate 202 of the steel structure S-beam is aligned one by one with the transverse screw hole 105 at the axial node position on the steel-concrete beam section 1 close to the foundation pit wall, and a transverse tension screw 8 is inserted therein, and both ends of the transverse tension screw 8 are fixed with nuts 10; the other end plate 202 of the steel structure S-beam is fixed to the crown beam 17 or the waist beam 18 with bolts 21.

[0050] Preferably, there are three ways to connect one side of the axial node with the steel structure auxiliary support 2. The first way is: one side of the axial node is connected to a steel structure auxiliary support 2, and the end plate 202 is connected to the axial node across the seam, that is, the No. 1 hole 202-1 of the end plate 202 is respectively connected to the transverse screw hole 105 on one side of the end of the two steel-concrete beam sections 1 connected at the axial node, and is fixed with a transverse tension screw 8 and a nut 10; The second type is: one side of the axial node is connected to two steel structure auxiliary supports 2, a side connection steel plate 11 is arranged on one side of the axial node, and the side connection steel plate 11 has four rows of No. 5 holes 1101, and the spans correspond to the two rows of transverse screw holes 105 on the sides of the two steel-concrete beam sections 1 at the axial node, and also correspond to the No. 1 holes 202-1 on the end plates 202 of the two steel structure auxiliary supports 2. After the transverse tension screw 8 passes through the coaxial No. 1 hole 202-1, No. 5 hole 1101 and transverse screw hole 105, both ends are tightened with nuts 10; The third type is: there is no auxiliary support connection on one side of the axial node, the axial node is installed on this side with a connecting steel plate 11, and the transverse tension screw 8 is passed through the No. 5 hole 1101 and the transverse screw hole 105, and the two ends of the transverse tension screw 8 are fixed with nuts 10.

[0051] Preferably, angle steels 24 are welded at the four corners where the connecting steel plate 12 is connected to the side connecting steel plate 11 or at the four corners where the connecting steel plate 12 is connected to the auxiliary supporting end plate.

[0052] Preferably, the adjustment system is divided into a mid-beam adjustment system and a beam end adjustment system; the mid-beam adjustment system includes a force-retaining steel structure 5 and a jack 4 placed on the force-retaining steel structure 5, and the beam end adjustment system includes a force-retaining head 1406, a gasket 1407 and a jack 4 arranged on a cap 14; the force-retaining steel structure 5 is composed of a part A 501, a part B 502, a steel sheet 503, an insert ring 504, and an insert plate 505; the part A 501 is composed of two long steel plates and a steel partition plate vertically welded between the two long steel plates , wherein a connecting plate is welded on one side of a long steel plate, and a No. 3 hole 501-1 is formed on the connecting plate; a force box 501-2 is welded on one side of another long steel plate, and the force box 501-2 is formed by welding steel plates; part B 502 is composed of two long steel plates and a steel partition plate vertically welded between the two long steel plates, wherein a connecting plate is welded on one side of one long steel plate, and a No. 4 hole 502-1 is formed on the connecting plate; a jack support 502-2 and a protruding steel plate 502-3 are welded on one side of another long steel plate, The jack support 502-2 is formed by welding a semicircular steel plate to a long steel plate; the height of the long steel plate and several steel partitions is the same as the cross-sectional height of the steel-concrete beam section 1; the connecting plates are in a group of two, and the distance between the two connecting plates is the same as the cross-sectional width of the steel-concrete beam section 1; the insert ring 504 is welded to the side of the force box 501-2 at both ends of the A part 501 and the side of the two ends of the B part 502; the arrangement of the third hole 501-1 and the fourth hole 502-1 and the transverse screw hole 105 of the steel-concrete beam section 1 and the hole The diameters are the same, and the width of the steel sheet 503 is the same as that of the force box 501-2; the force box 501-2 of part A is placed on the protruding steel plate 502-3 of part B 502, and the connection between part A 501 and part B 502 is achieved by inserting the plug plate 505 into the plug ring 504; the connection between the force-retaining steel structure 5 and the main support is achieved by making the fourth hole 502-1 on the connecting plate correspond to the transverse screw hole 105 at the end of the main support one by one, inserting the transverse tension screw 8 and tightening it with the nut 10.

[0053] Preferably, there are two types of caps 14, one type of cap 14 is composed of embedded steel plates 1401, embedded steel bars 1402, cap bottom plates 1403, and cap side plates 1404; the other type of cap 14 is composed of embedded steel plates 1401, embedded steel bars 1402, cap bottom plates 1403, cap side plates 1404, jack wooden supports 1405, force-retaining heads 1406, and gaskets 1407; the force-retaining heads 1406 are formed by welding I-beams and steel plates, the steel plate size of the force-retaining heads 1406 is the same as the cross-sectional size of the steel-concrete beam section 1, the embedded steel plates 1401 are all arranged at the corbels 19, and embedded steel bars 1402 are welded to one side of the embedded steel plates 1401.

[0054] Preferably, the L-shaped embedded holes 1701 and the I-shaped embedded holes 1801 are respectively preset in the crown beam 17 and the waist beam 18 every 3-5 m; The L-shaped embedded hole 1701 is formed by embedding an L-shaped PVC tube 22 in the crown beam 17. The L-shaped PVC tube 22 has two openings at both ends, one end is opened on the upper surface of the crown beam 17, and the other end is opened on the side of the crown beam 17. The embedded position of the L-shaped PVC tube 22 is staggered with the position of the corbel 19. The I-shaped embedded hole 1801 is formed by embedding an I-shaped PVC pipe 23 in the waist beam 18. Both ends of the I-shaped PVC pipe 23 are open, one end is located on the top surface of the waist beam 18, and the other end is located on the bottom surface of the waist beam 18. The I-shaped PVC pipe 23 is embedded on one side of the waist beam 18 close to the supporting pile 3, and the embedded position of the I-shaped PVC pipe 23 is staggered with the position of the corbel 19.

[0055] Preferably, the method for dismantling the prefabricated steel-concrete-steel structure foundation pit support system comprises the following steps: 1) Prepare the wire saw cutting machine, support frame, crane, forklift and other machines and tools, and arrange the location and access channels of the machines and tools; 2) After the foundation slab is constructed, wait until it reaches 80% of the design strength, then construct the floor slab below the lowest support. After the support is replaced, prepare to remove the lowest support; 3) The jack 4 is extended, the jack 4 on the beam adjustment system extends the A part 501 of the force-retaining steel structure 5, and the jack 4 on the beam end adjustment system extends the force-retaining head 1406; the gasket 1407 and the steel sheet 503 are removed, the pressure of the jack 4 is reduced to 0, and the jack 4, the force-retaining head 1406 and the jack wooden support 1405 are removed; 4) Use a cutting machine to cut the angle steel 24 at the axial node of the main support; remove the steel structure auxiliary support 2 of the lowest support: after setting up the support frame under the steel structure auxiliary support 2, loosen the nut 10, remove the transverse tension screw rod 8 and bolt 21, remove the side connection steel plate 11, and then use a forklift or crane to transport the steel structure auxiliary support 2 out of the foundation pit; 5) Dismantle the steel-concrete beam sections 1 of all the main supports of the lowest support row by row: start dismantling each row of main supports from the pedestal with jacks 4 or from the protective steel structure 5, set up a support frame under the steel-concrete beam section 1 to be dismantled, and use a cutting machine to cut the pedestal 14 and the hoop 20; remove the transverse tension screws 8 and nuts 10 connecting the protective steel structure 5 and the steel-concrete beam section 1, pull out the plug plate 505 in the plug ring 504, and dismantle the A part 501 and B part of the protective steel structure 5. Part 502; Use a forklift and a crane to transport the disassembled part A 501 and part B 502 of the Baoli steel structure 5 out of the foundation pit; Loosen the anchor heads 25 at both ends of the inclined cable 9, pull out the inclined cable 9 and the vertical tension screw 7 at the axial node of the main support, remove the connecting steel plate 12 and the inclined cable adjuster 13; Use a forklift to pull out the steel-concrete beam section 1 from the axial node one by one along the axial direction, and then pull out the connecting round steel 6; Use a crane to transport the disassembled steel-concrete beam section 1 out of the foundation pit; 6) Set up a support frame under the lower supporting waist beam 18 and its upper corbel 19; 7) Use a rope saw to cut the corbel 19; after clearing the I-shaped pre-buried hole 1801 of the lower supporting waist beam 18, insert the rope saw chain into the I-shaped pre-buried hole 1801, turn on the rope saw cutting machine, and cut the waist beam 18; the cut waist beam section and corbel 19 are transported out of the foundation pit by forklift and crane; 8) Repeat steps 2) to 7) to complete the removal of all non-first support; 9) Construct the floor slab below the first support, and after replacing the support, prepare to remove the first support; 10) Repeat steps 3), 4), and 5 to complete the removal of the main support, steel structure auxiliary support 2, and adjustment system of the first internal support system; 11) Set up a support frame under the corbel 19 of the first supporting crown beam 17; 12) Use a rope saw to cut the corbel 19; after clearing the L-shaped pre-buried hole 1701 of the first supporting crown beam 17, insert the rope saw chain into the L-shaped pre-buried hole 1701, turn on the rope saw cutting machine, cut the crown beam 17, and transport the cut crown beam section and corbel 19 out of the foundation pit by forklift or crane; 13) The steel lattice columns 16 are cut using a cutting machine, and the cut steel lattice columns 16 are transported out of the foundation pit by a crane.

[0056] Example 1 For a certain foundation pit, the general excavation depth is 14.75-16.20 m, the perimeter of the foundation pit is about 586 m, and the basement excavation area is about 20,537 m2.

[0057] Design three foundation pit internal supports. The main supports of the three supports use steel-concrete beam sections. The internal support plane layout is as follows: Fig.21 As shown; each internal support includes four corner braces arranged at the four corners of the foundation pit and one brace arranged in the middle of the foundation pit. The cross-section design height of the crown beam 17 is 1000 mm and the width is 1200 mm. The outer diameter of the L-shaped PVC pipe 22 is 40 mm, and one is set every 3-5 m; the size of the waist beam 18 is 1000 mm×1000 mm, and the outer diameter of the I-shaped PVC pipe 23 is 40 mm, and one is set every 3-5 m; the column piles are bored cast-in-place piles ⌀800mm, a total of 117 piles, and the concrete strength of the pile body is C30; 62 brackets are set on the crown beam 17 and the waist beam 18, and the cross-section size of the bracket is 1020 mm×1000 mm.

[0058] There are two types of caps 14 on the corbels 19; there are 28 caps 14 for placing the jacks 4, the embedded steel plate 1401 is 20 mm thick, 1000 mm high and 1020 mm wide, the embedded steel bars 1402 are HRB400 with a diameter of 10 mm, one row is welded on each side of the steel plate, and a total of 16 are welded, the bottom plate 1403 of the cap 14 is 20 mm thick, 1020 mm wide and 1300 mm long, the side plate 1404 of the cap 14 is 20 mm thick, the semicircular groove of the jack wooden support 1405 is 600 mm in diameter and 100 mm in length, the force head 1406 uses a steel plate with a thickness of 20 mm, a width of 1000 mm and a height of 1000 mm, two 50a I-beams are welded on each side of the left and right sides, and the size after stacking is 1000 mm high and 160 mm wide. There are 34 caps 14 without jacks, with embedded steel plates 1401 of 20 mm thickness, 1000 mm height and 1020 mm width, embedded steel bars 1402 of HRB400 with a diameter of 10 mm, one row welded on each side of the steel plate, 16 in total, cap bottom plate 1403 of 20 mm thickness, 1020 mm width and 500 mm length, and cap side plates 1404 of 20 mm thickness.

[0059] The cross-sectional dimensions of the steel lattice column 16 are 460 mm × 460 mm. The tie material of the steel lattice column 16 is long angle steel, the long angle steel is L140 × L14, the tie plate thickness is 10 mm, the height is 400 mm, the width is 460 mm, and the tie plate spacing is 600 mm.

[0060] The pallet 15 has a thickness of 20 mm, a width of 860 mm, and a length of 1860 mm. A right-angled triangular steel plate is welded to the bottom of the pallet 15. One side of the right-angled triangular steel plate is welded to the pallet 15, and the other side is welded to the lattice column 16. The thickness of the steel plate is 20 mm.

[0061] The adjustment system includes 1 mid-beam adjustment system and 28 beam end adjustment systems, using a total of 32 jacks, and 500-ton hydraulic jacks 4 are selected; the mid-beam adjustment system includes a retaining steel structure 5 and 4 jacks, and the 6 main supports are connected into 3 rows of main supports through the adjustment system.

[0062] The mid-beam adjustment system includes a force-retaining steel structure 5 and a jack 4 placed on the force-retaining steel structure 5; the beam end adjustment system includes a force-retaining head 1406, a gasket 1407 and a jack 4 placed on the pedestal 14 arranged at one end of the main support, the gasket 1407 is 10mm thick, and the gasket is 1000mm high and 1000mm wide. The force-retaining steel structure 5 consists of a part A 501, a part B 502, a steel sheet 503, an insert ring 504, and an insert plate 505; the part A 501 is formed by welding two long steel plates with a length of 11000mm, a height of 1000mm and a thickness of 20mm and a steel partition with a length of 1000mm, a height of 1000mm and a thickness of 20mm, and the two long steel plates are welded and connected by a steel partition perpendicular to the long steel plates; wherein, a connecting plate with a length of 500mm, a height of 1000mm and a thickness of 20mm is welded on one side of a long steel plate, and the connecting plate has two rows of six No. 3 holes 501-1, and the No. 3 holes 501-1 are adapted to the transverse screw holes 105; a force-retaining box 501-2 is welded on one side of the other long steel plate, and the force-retaining box 501-2 is formed by welding a steel plate with a height of 1000mm and a thickness of 20mm; the part B 502 is formed by welding two long steel plates with a length of 11000mm, a height of 1000mm A 20mm thick long steel plate and a 1000mm long, 1000mm high, 20mm thick steel partition are welded together. The two long steel plates are connected by welding a steel partition perpendicular to the long steel plate. A connecting plate 500mm long, 1000mm high, and 20mm thick is welded on one side of one long steel plate. There are two rows of six No. 4 holes 502-1 on the connecting plate. The No. 4 holes 502-1 are matched with the transverse screw holes 105. A jack support 502-2 and a protruding steel plate 502-3 with a length of 500mm, a width of 1000mm, and a thickness of 20mm are welded on one side of the other long steel plate. The jack support 502-2 is formed by welding a 20mm thick semicircular steel plate on the long steel plate; plug rings 504 are welded on the side surfaces of the two end heads of part A 501 and part B 502, totaling 12, and a plug plate 505 with a cross-sectional size of 100mm×20mm is inserted into the plug ring 504.

[0063] Each row of main supports in the axial bracing is composed of 12 steel-concrete beam segments 1 axially connected, and the four corner supports are 7 rows each. The 7 rows of main supports are composed of 2, 4, 6, 8, 10, 12, and 14 steel-concrete beam segments 1 respectively; both ends of each row of main supports are placed on the pedestal 14.

[0064] A steel plate with a thickness of 20 mm and a width of 100 mm is selected for welding to form a hoop 20 , which fixes the main support on the pallet 15 , with one end welded to the pallet 15 and the other end welded to the steel lattice column 16 .

[0065] In each inner support, there are 184 steel structure auxiliary supports 2 connecting the adjacent main supports, and there are 4 steel structure S-beams.

[0066] The steel structure auxiliary support 2 used for connecting adjacent main supports is formed by welding a frame 201 and an end plate 202; the frame 201 is an H-shaped steel, and the model of the H-shaped steel is H500×500; the end plate 202 is a steel plate, and the end plate is 1000mm high and 1000mm wide, and is provided with two rows of No. 1 holes 202-1 for connection, the aperture of the No. 1 hole 202-1 is 30mm, and the row spacing of the two rows of No. 1 holes 202-1 is 720mm, which is compatible with the transverse screw hole 105.

[0067] The steel structure auxiliary support 2 used for the steel structure S-beam is formed by welding a frame 201 and an end plate 202; the frame 201 is an H-shaped steel, and the model of the H-shaped steel is H600mm×600mm; the end plate 202 is a steel plate, on which two rows of No. 1 holes 202-1 for connection are arranged, the hole diameter of the No. 1 hole 202-1 is 30mm, the row spacing between the two rows of No. 1 holes 202-1 is 720mm, and the No. 1 hole 202-1 is compatible with the transverse screw hole 105.

[0068] The cross-sectional width of the steel-concrete beam section 1 is 1000 mm, the cross-sectional height is 1000 mm, and the length is 5 m. The end of the steel-concrete beam section 1 is provided with two rows of six vertical screw holes 104 (three holes in each row), two columns of six transverse screw holes 105 (three holes in each column), and two columns of four longitudinal rebar holes 103 (two holes in each column). In the middle part of the rectangular reinforced concrete 102, symmetrically to the middle section of the steel-concrete beam section 1, two rows of six inclined cable holes 106 (three in each row) are arranged. (At a certain end position of the steel-concrete beam section 1, when the line connecting the hole centers of the multiple vertical screw holes 104 on the same plane is parallel to the end surface of the steel-concrete beam section, these holes constitute a row of vertical screw holes 105; when the line connecting the hole centers of the multiple transverse screw holes 105 on the same plane is parallel to the end surface of the steel-concrete beam section 1, these holes constitute a row of transverse screw holes 105; when the line connecting the hole centers of the multiple longitudinal reinforcing bar holes 103 on the same plane is parallel to the side surface of the steel-concrete beam section 1, these holes constitute a row of longitudinal reinforcing bar holes 103; when the line connecting the hole centers of the multiple inclined cable holes 106 on the same plane is perpendicular to the side surface of the steel-concrete beam section 1, these holes constitute a row of inclined cable holes 106, the same below) The hole plane layout of the vertical screw hole 104 is a rectangular hole layout with a hole diameter of 30mm, a row spacing of 200mm, a hole spacing of 300mm, a distance from the outermost row of holes to the end face of 250mm, and a distance from the outermost hole in each row of holes to the adjacent end side of 200mm.

[0069] The hole plane layout of the transverse screw holes 105 is a rectangular hole layout with a hole diameter of 30mm, a row spacing of 240mm, a hole spacing of 300mm, a distance of 120mm from the outermost row of holes to the end face of the steel-concrete beam section 1, and a distance of 200mm from the uppermost hole in each row of transverse screw holes 105 to the upper surface.

[0070] The hole opening plane layout of the longitudinal reinforcement holes 103 is a rectangular hole layout, with a hole diameter of 40mm, a hole depth of 500mm, a row spacing of 400mm, a hole spacing of 400mm, a distance from the top hole to the upper surface of 300mm, and a distance from the left hole to the left side of the steel-concrete beam section 1 of 300mm.

[0071] The hole diameter of the cable-stayed hole 106 is 30 mm, the inclination angle is 45°, the hole openings are arranged in a rectangular pattern on the upper surface of the steel-concrete beam section 1, the hole spacing is 300 mm, the row spacing is 1000 mm, and the distance from the hole openings of each row of holes on the upper surface of the steel-concrete beam section 1 to the end face of the adjacent steel-concrete beam section 1 is 2000 mm, and the distance from the outermost holes of each row to the side face of the adjacent steel-concrete beam section 1 is 200 mm.

[0072] A steel plate with a size of 800mm×500mm×10mm is selected as the upper and bottom steel plates of the beam sleeve 101. The diameter, row spacing and hole spacing of the holes on it are the same as those of the vertical screw holes 104. The edge of the steel plate with a length of 500mm is welded to the angle steel. A steel plate with a size of 800mm×500mm×10mm is selected as the side steel plate of the beam sleeve 101. The diameter, row spacing and hole spacing of the holes on it are the same as those of the transverse reinforcement holes 105. The edge of the steel plate with a length of 500mm is welded to the angle steel. An angle steel with a model of L100×10 and a length of 5m is selected as the angle steel of the beam sleeve 101.

[0073] The structure of the axial node is as follows: the end faces of the two steel-concrete beam sections 1 are closely fitted, and a connecting steel plate 12 with a length of 1000mm, a width of 1000mm and a thickness of 20mm is provided on each span of the upper and lower surfaces of the fitting, and four rows of twelve No. 6 holes 1201 are opened on the connecting steel plate 12, and the No. 6 holes 1201 have a diameter of 30mm and are adapted to the vertical screw holes 104, and the longitudinal dowel holes 103 on the end faces of the two steel-concrete beam sections 1 are aligned one by one and inserted with round steel bars 6; The diameter of the round steel 6 is 34 mm; the thickness of the connecting steel plate 12 is 20 mm, the width is 1000 mm, and the length is 1000 mm; the diameter of the horizontal tension screw 8 is 24 mm; and the diameter of the vertical tension screw 7 is 24 mm.

[0074] The inclined cable adjuster 13 is composed of an adjuster base plate 1301, an adjusting screw 1302, an adjuster support rod 1303, a web 1304, a left-handed nut 1305, a fixing piece 1306, a right-handed nut 1307, and a pin 1308; the adjuster base plate 1301 of the inclined cable adjuster 13 is 1000mm long, 1000mm wide, and 20mm thick. There are two rows of six No. 2 holes 1301-1 on the adjuster base plate 1301. The aperture of the No. 2 hole 1301-1 is 30mm and is compatible with the vertical screw hole 104. Two fixing pieces 1306 are welded on the web 1304 and the adjusting base plate 1301. The web 1304 is 20mm thick. Each fixing piece 1306 is welded on the web 1304. There are two pins 1308 on the joint 1306, and the two pins 1308 are connected to two adjuster support rods 1303, the diameter of the adjuster support rods 1303 is 30 mm, and the other ends of the two adjuster support rods 1303 are respectively connected to a right-handed nut 1307 and a left-handed nut 1305 through the pins 1308. There is a handle 1302-3 at the end of the adjusting screw 1302, and the diameter of the adjusting screw 1302 is 40 mm. Two groups of positive and negative threads are arranged on the adjusting screw 1302, and each group of positive and negative threads includes a right-handed thread 1302-1 and a left-handed thread 1302-2; each group of positive and negative threads is equipped with a right-handed nut 1307 and a left-handed nut 1305.

[0075] The No. 1 hole 202-1 of one end plate 202 of the steel structure S-beam is aligned one by one with the transverse screw hole 105 at the axial node position on the steel-concrete beam section 1 close to the foundation pit wall, and a transverse tension screw 8 is inserted therein, and both ends of the transverse tension screw 8 are fixed with nuts 10; the other end plate 202 of the steel structure S-beam is fixed to the crown beam 17 or the waist beam 18 with bolts 21.

[0076] One side of the axial node is connected to a steel structure auxiliary support 2, and the end plate 202 is connected to the axial node across the seam, that is, the No. 1 hole 202-1 of the end plate 202 is respectively connected to the transverse screw hole 105 on one side of the end of the two steel-concrete beam sections 1 connected at the axial node, and is fixed with a transverse tension screw 8 and a nut 10.

[0077] There is no auxiliary support connection on one side of the axial node. The side connecting steel plate 11 is installed on this side of the axial node, and the transverse tension screw 8 passes through the No. 5 hole 1101 and the transverse screw hole 105, and is fixed with a nut 10. The side connecting steel plate 11 is 1000mm high, 1000mm wide and 20mm thick. There are four rows of twelve No. 5 holes 1101 on it, and the row spacing is 240mm. The aperture of the No. 5 hole 1101 is 30mm, which is compatible with the transverse screw hole 105.

[0078] 1. Prepare wire saw cutting machine, support frame, crane, forklift and other machines and tools, and arrange the location and access channels of the machines and tools; 2. After the foundation slab is constructed and reaches 80% of the design strength, the floor slab below the third support is constructed, plain concrete is used to replace the support, and then the third support is removed; 3. The jack 4 is extended. The jack 4 on the beam adjustment system extends the A part 501 of the force-retaining steel structure 5. The jack 4 on the beam end adjustment system extends the force-retaining head 1406. The gasket and the steel sheet are removed. The pressure of the jack 4 is reduced to 0. The jack 4, the force-retaining head 1406 and the jack wooden support 1405 are removed. 4. Use a cutting machine to cut the angle steel at the axial node of the main support, and then remove the steel structure auxiliary support 2 of the third support row by row. First, set up a support frame under the steel structure auxiliary support 2, and then remove the nuts that fix the transverse tension screws 105, and at the same time unscrew the fixing bolts of the steel structure auxiliary support 2 used as the eight-shaped beam; after pulling out the transverse tension screws 105 connecting the steel structure auxiliary support 2 and the steel-concrete beam section 1, remove the side connection steel plate 11, remove the steel structure auxiliary support 2 with a forklift, and then use a crane to transport the steel structure auxiliary support 2 out of the foundation pit; 5. Remove the third supported steel-concrete beam section 1 row by row, and set up a support frame under the steel-concrete beam section 1; cut the cap 14 and the hoop 20 with a cutting machine; remove the transverse tension screws 105 and nuts 10 connecting the force-retaining steel structure 5 and the steel-concrete beam section 1, and use a forklift and a crane to transport the removed A part 501 and B part of the force-retaining steel structure 5 out of the foundation pit; remove the inclined cable 9 and the vertical tension screws 7 at the main support node, and remove the connecting steel plate 12, the inclined cable adjuster 13, and the nut 10; remove the steel-concrete beam section 1 with a forklift, and pull out the round steel inserted in the longitudinal reinforcement hole 103; and then use a crane to transport the removed steel-concrete beam section 1 out of the foundation pit; 6. Set up a support frame under the third supporting waist beam 17 and its upper corbel 19; 7. Use a rope saw to cut the corbel 19 on the third supporting waist beam; remove the plaster at both ends of the I-shaped pre-buried hole for rope saw cutting of the third supporting waist beam 17. After cleaning, insert the rope saw chain into the I-shaped pre-buried hole, turn on the rope saw cutting machine, and cut the waist beam; the cut waist beam section and corbel 19 are transported out of the foundation pit by forklift and crane; 8. Repeat steps 2) to 7) to complete the removal of the second support. 9. After the construction of the floor slab and plain concrete replacement support structure under the first support is completed and the concrete reaches 80% of the design strength, the first support is removed; 10. The jack 4 is extended. The jack 4 on the beam adjustment system extends the A part 501 of the force-retaining steel structure 5. The jack 4 on the beam end adjustment system extends the force-retaining head 1406. The gasket and the steel sheet are removed. The pressure of the jack 4 is reduced to 0. The jack 4, the force-retaining head 1406 and the jack wooden support 1405 are removed. 11. Use a cutting machine to cut the angle steel at the axial node of the main support, and then remove the steel structure auxiliary support 2 of the first support row by row. First, set up a support frame under the steel structure auxiliary support 2, and then remove the nuts that fix the transverse tension screws 105, and at the same time unscrew the fixing bolts of the steel structure auxiliary support 2 used as the eight-shaped beam; after pulling out the transverse tension screws 8 connecting the steel structure auxiliary support 2 and the steel-concrete beam section 1, remove the side connection steel plate 11, remove the steel structure auxiliary support 2 with a forklift, and then use a crane to transport the steel structure auxiliary support 2 out of the foundation pit; 12. Remove the first supporting steel-concrete beam section 1 row by row, and set up a support frame under the steel-concrete beam section 1; cut the cap 14 and the hoop 20 with a cutting machine; remove the transverse tension screws and nuts connecting the force-retaining steel structure 5 and the steel-concrete beam section 1, and use a forklift and a crane to transport the removed A part 501 and B part of the force-retaining steel structure 5 out of the foundation pit; remove the inclined cable 9, vertical tension screws 7, connecting steel plates 11, inclined cable adjusters 13, and nuts 10 at the main support nodes; remove the steel-concrete beam section 1 with a forklift, and pull out the round steel 6 inserted in the longitudinal reinforcement hole; then use a crane to transport the removed steel-concrete beam section 1 out of the foundation pit; 13. Set up a support frame under the corbel 19 of the crown beam of the first support; 14. Use a rope saw to cut the lower corbel 19; remove the plaster at both ends of the L-shaped pre-buried hole of the first supporting crown beam. After the cleaning is completed, insert the rope saw chain into the L-shaped pre-buried hole, turn on the rope saw cutting machine, cut the crown beam, and transport the cut crown beam section and corbel 19 out of the foundation pit by forklift and crane; 15. Use a wire saw cutting machine to cut the steel lattice column 16, and the cut steel lattice column 16 is transported out of the foundation pit by a crane; Example 2 For a certain foundation pit, the general excavation depth is 24.75-25.20 m, the perimeter of the foundation pit is 374 m, and the basement excavation area is approximately 8687 m2.

[0079] Design five foundation pit internal supports. The main supports of the five supports use steel-concrete beam section 1. The internal support plane layout is as follows: Fig. 22 As shown; each internal support includes 4 corner braces arranged at the four corners of the foundation pit. The cross-section design height of the crown beam 17 is 1200 mm and the width is 1400 mm. The L-shaped PVC pipe 22 has an outer diameter of 40 mm and is set every 3-5 m. The size of the waist beam 18 is 1000 mm×1000 mm, and the outer diameter of the I-shaped PVC pipe 23 is 40 mm, and it is set every 3-5 m. The column piles are bored cast-in-place piles ⌀800mm, with a total of 36 piles, and the concrete strength of the pile body is C30; 40 brackets 19 are set on the crown beam 17 and the waist beam 18, and the cross-section size of the bracket 19 is 1020 mm×1000mm.

[0080] Two types of caps 14 are arranged on the corbels 19; the caps 1420 for placing the jacks 4 have a thickness of 20 mm, a height of 1000 mm, and a width of 1020 mm. The embedded steel plates 1401 are HRB400 with a diameter of 10 mm. The steel plates are welded in a row on both sides, with a total of 16 welded. The bottom plate 1403 of the cap 14 has a thickness of 20 mm, a width of 1020 mm, and a length of 1300 mm. The side plate 1404 of the cap 14 has a thickness of 20 mm. The semicircular groove of the jack wooden support 1405 has a diameter of 600 mm and a length of 100 mm. The force head 1406 uses a steel plate with a thickness of 20 mm, a width of 1000 mm, and a height of 1000 mm. Two 50a I-beams are welded on each side of the left and right sides. The size after stacking is 1000 mm high and 160 mm wide. mm; there are 1420 caps without jacks 4, whose embedded steel plates 1401 are 20 mm thick, 1000 mm high and 1020 mm wide, and the embedded steel bars 1402 are HRB400 with a diameter of 10 mm. There are one row welded on each side of the steel plates, for a total of 16 steel bars. The bottom plate 1403 of the cap 14 is 20 mm thick, 1020 mm wide and 500 mm long, and the side plate 1404 of the cap 14 is 20 mm thick.

[0081] The cross-sectional dimensions of the steel lattice column 16 are 460 mm × 460 mm. The tie material of the steel lattice column 16 is long angle steel, the long angle steel is L140 × L14, the tie plate thickness is 10 mm, the height is 400 mm, the width is 460 mm, and the tie plate spacing is 600 mm.

[0082] The pallet 15 is 20 mm thick, 860 mm wide and 1860 mm long. A right-angle triangular steel plate is welded under the pallet 15. One side of the steel plate is welded to the pallet 15, and the other side is welded to the lattice column 16. The thickness of the steel plate is 20 mm.

[0083] The adjustment system includes 20 beam end adjustment systems, using a total of 20 jacks 4, and 500-ton hydraulic jacks 4 are selected; There are 5 rows of four corner supports each, and the 7 rows of main supports are composed of 2, 4, 6, 8, and 10 steel-concrete beam segments 1 respectively; both ends of each row of main supports are placed on the pedestal 14.

[0084] A steel plate with a thickness of 20 mm and a width of 100 mm is selected for welding to form a hoop 20 , which fixes the main support on the pallet 15 , with one end welded to the pallet 15 and the other end welded to the steel lattice column 16 .

[0085] In each inner support, 80 steel structure auxiliary supports 2 are connected between adjacent main supports.

[0086] The steel structure auxiliary support 2 used for connecting adjacent main supports is formed by welding a frame 201 and an end plate 202; the frame 201 is an I-beam with a waist height of 600mm and a leg width of 200mm; the end plate 202 is a steel plate with a height of 1000mm and a width of 500mm, on which two rows of No. 1 holes 202-1 for connection are arranged, the aperture of the No. 1 hole 202-1 is 30mm, the row spacing between the two rows of No. 1 holes 202-1 is 240mm, and the No. 1 hole 202-1 is compatible with the transverse screw hole 105.

[0087] The cross-sectional width of the steel-concrete beam section 1 is 1000 mm, the cross-sectional height is 1000 mm, and the length is 5 m. The end of the steel-concrete beam section 1 is provided with two rows of six vertical screw holes 104 (three holes in each row), two columns of six transverse screw holes 105 (three holes in each column), and two columns of four longitudinal rebar holes 103 (two holes in each column). In the middle part of the rectangular reinforced concrete 102, symmetrically to the middle section of the steel-concrete beam section 1, two rows of six inclined cable holes 106 (three in each row) are arranged.

[0088] The hole plane layout of the vertical screw hole 104 is a rectangular hole layout with a hole diameter of 30mm, a row spacing of 200mm, a hole spacing of 300mm, a distance from the outermost row of holes to the end face of 250mm, and a distance from the outermost hole in each row of holes to the adjacent end side of 200mm.

[0089] The hole plane layout of the transverse screw holes 105 is a rectangular hole layout with a hole diameter of 30mm, a row spacing of 240mm, a hole spacing of 300mm, a distance of 120mm from the outermost row of holes to the end face of the steel-concrete beam section 1, and a distance of 200mm from the uppermost hole in each row of transverse screw holes 105 to the upper surface.

[0090] The hole opening plane layout of the longitudinal reinforcement holes 103 is a rectangular hole layout, with a hole diameter of 40mm, a hole depth of 500mm, a row spacing of 400mm, a hole spacing of 400mm, a distance from the top hole to the upper surface of 300mm, and a distance from the left hole to the left side of the steel-concrete beam section 1 of 300mm.

[0091] The hole diameter of the cable-stayed hole 106 is 30 mm, the inclination angle is 45°, the hole openings are arranged in a rectangular pattern on the upper surface of the steel-concrete beam section 1, the hole spacing is 300 mm, the row spacing is 1000 mm, and the distance from the hole openings of each row of holes on the upper surface of the steel-concrete beam section 1 to the end face of the adjacent steel-concrete beam section 1 is 2000 mm, and the distance from the outermost holes of each row to the side face of the adjacent steel-concrete beam section 1 is 200 mm.

[0092] A steel plate with a size of 800mm×500mm×10mm is selected as the upper and bottom steel plates of the beam sleeve 101. The diameter, row spacing and hole spacing of the holes on it are the same as those of the vertical screw holes 104. The edge of the steel plate with a length of 500mm is welded to the angle steel. A steel plate with a size of 800mm×500mm×10mm is selected as the side steel plate of the beam sleeve 101. The diameter, row spacing and hole spacing of the holes on it are the same as those of the transverse reinforcement holes 105. The edge of the steel plate with a length of 500mm is welded to the angle steel. An angle steel with a model of L100×10 and a length of 5m is selected as the angle steel of the beam sleeve 101.

[0093] The structure of the axial node is as follows: the end faces of the two steel-concrete beam sections 1 are closely fitted, and a connecting steel plate 12 with a length of 1000mm, a width of 1000mm and a thickness of 20mm is provided on each span of the upper and lower surfaces of the fitting, and four rows of twelve No. 6 holes 1201 are opened on the connecting steel plate 12, and the No. 6 holes 1201 have a diameter of 30mm and are adapted to the vertical screw holes 104, and the longitudinal dowel holes 103 on the end faces of the two steel-concrete beam sections 1 are aligned one by one and inserted with round steels 6; The diameter of the round steel 6 is 34 mm; the thickness of the connecting steel plate 12 is 20 mm, the width is 1000 mm, and the length is 1000 mm; the diameter of the horizontal tension screw 8 is 24 mm; and the diameter of the vertical tension screw 7 is 24 mm.

[0094] One side of the axial node is connected to a steel structure auxiliary support 2, and the end plate 202 is connected to the axial node across the seam, that is, the No. 1 hole 202-1 of the end plate 202 is respectively connected to the transverse screw hole 105 on one side of the end of the two steel-concrete beam sections 1 connected at the axial node, and is fixed with a transverse tension screw 8 and a nut 10.

[0095] One side of the axial node is connected to two steel structure auxiliary supports 2. A side connection steel plate 11 is provided on one side of the axial node. The side connection steel plate 11 is 1000mm high, 1000mm wide, and 20mm thick. There are four rows of twelve No. 5 holes 1101 on it, and the row spacing is 240mm. The aperture of the No. 5 hole 1101 is 30mm. The span corresponds to the two rows of transverse screw holes 105 on the sides of the two steel-concrete beam sections 1 at the axial node, and also corresponds to the No. 1 holes 202-1 on the end plates 202 of the two steel structure auxiliary supports 2. After the transverse tension screw 8 passes through the coaxial No. 1 hole 202-1, No. 5 hole 1101 and transverse screw hole 105, both ends are tightened with nuts 10; There is no auxiliary support connection on one side of the axial node. The side connecting steel plate 11 is installed on this side of the axial node, and the transverse tension screw 8 passes through the No. 5 hole 1101 and the transverse screw hole 105, and is fixed with a nut 10. The side connecting steel plate 11 is 1000mm high, 1000mm wide and 20mm thick. There are four rows of twelve No. 5 holes 1101 on it, and the row spacing is 240mm. The aperture of the No. 5 hole 1101 is 30mm, which is compatible with the transverse screw hole 105.

[0096] 1. Prepare wire saw cutting machine, support frame, crane, forklift and other equipment, and arrange the location and access passage of equipment; 2. After the foundation slab is constructed and reaches 80% of the design strength, the floor slab below the fifth support is constructed, plain concrete is used to replace the support, and then the fifth support is removed; 3. Extend the jack 4, extend the force head 1406 on the beam end adjustment system, remove the gasket, reduce the pressure of the jack 4 to 0, remove the jack 4, the force head 1406 and the jack wooden support 1405; 4. Use a cutting machine to cut the angle steel at the main support node, and then remove the steel structure auxiliary support 2 of the fifth support row by row. First, set up a support frame under the steel structure auxiliary support 2, then remove the nuts that fix the transverse tension screws, then pull out the transverse tension screws connecting the steel structure auxiliary support 2 and the steel-concrete beam section 1, and remove the lateral connection steel plate; finally, use a forklift to remove the steel structure auxiliary support 2, and use a crane to transport the steel structure auxiliary support 2 out of the foundation pit; 5. Remove the fifth supporting steel-concrete beam section 1 row by row, and set up a support frame under the steel-concrete beam section 1; use a cutting machine to cut the cap 14 and the clamp 20; remove the inclined cable 9 and the vertical tension screw 7 at the main support node, and remove the connecting steel plate 11, the inclined cable adjuster 13, and the nut 10; remove the steel-concrete beam section 1 with a forklift, and pull out the round steel 6 inserted in the longitudinal reinforcement hole; use a crane to transport the steel-concrete beam section 1 out of the foundation pit; 6. Set up a support frame under the fifth supporting waist beam and the corbel 19 on the waist beam; 7. Use a rope saw to cut the corbel 19 on the fifth supporting waist beam; remove the plaster at both ends of the I-shaped pre-buried hole of the fifth supporting waist beam for rope saw cutting. After the cleaning is completed, insert the rope saw chain into the I-shaped pre-buried hole, turn on the rope saw cutting machine, and cut the waist beam; the cut waist beam section and corbel 19 are transported out of the foundation pit by forklift and crane; 8. Repeat steps 2) to 7) to complete the removal of the second, third, and fourth supports; 9. After the construction of the floor slab and plain concrete replacement support structure under the first support is completed and the concrete reaches 80% of the design strength, the first support is removed; 10. Extend the jack 4, extend the force head 1406 of the jack 4 on the beam end adjustment system, remove the gasket, reduce the pressure of the jack 4 to 0, remove the jack 4, the force head 1406 and the jack wooden support 1405; 11. Use a cutting machine to cut the angle steel at the main support node, and then remove the first support steel structure auxiliary support 2 row by row. First, set up a support frame under the steel structure auxiliary support 2, then remove the nuts that fix the transverse tension screws, then pull out the transverse tension screws connecting the steel structure auxiliary support 2 and the steel-concrete beam section 1, and remove the lateral connection steel plate; finally, use a forklift to remove the steel structure auxiliary support 2, and use a crane to transport the steel structure auxiliary support 2 out of the foundation pit; 12. Remove the first supporting steel-concrete beam section 1 row by row, and set up a support frame under the steel-concrete beam section 1; use a cutting machine to cut the cap 14 and the hoop 20; remove the inclined cable 9 and the vertical tension screw 7 at the main support node, and remove the connecting steel plate 11, the inclined cable adjuster 13, and the nut 10; use a forklift to remove the steel-concrete beam section 1, and pull out the round steel 6 inserted in the longitudinal reinforcement hole; use a crane to transport the steel-concrete beam section 1 out of the foundation pit; 13. Set up a support frame under the corbel 19 of the crown beam of the first support; 14. Use a rope saw to cut the lower corbel 19; remove the plaster at both ends of the L-shaped pre-buried hole of the first supporting crown beam. After the cleaning is completed, insert the rope saw chain into the L-shaped pre-buried hole, turn on the rope saw cutting machine, cut the crown beam 17, and transport the cut crown beam section and corbel 19 out of the foundation pit by forklift and crane; 15. Use a wire saw cutting machine to cut the steel lattice column 16, and the cut steel lattice column 16 is transported out of the foundation pit by a crane; Example 3 For a certain foundation pit, the general excavation depth is 5.5-6.3 m, the perimeter of the foundation pit is about 539 m, and the basement excavation area is about 14,693 m2.

[0097] Design an internal support for the foundation pit. The main support uses a steel-concrete beam segment 1. The internal support plane layout is as follows: Fig.23 As shown; the internal support includes four pairs of braces. The cross-section design of the crown beam 17 is 1000 mm high and 1000 mm wide. The L-shaped PVC pipe 22 has an outer diameter of 40 mm and is set every 3-5 m. The column piles are bored cast-in-place piles ⌀800 mm, with a total of 70 piles, and the concrete strength of the pile body is C30. There are 20 brackets 19 on the crown beam 17 and the waist beam 18, and the cross-section size of the bracket 19 is 1020 mm×1000 mm.

[0098] A cap 14 is arranged on each of the corbels 19; there are 20 caps, and the embedded steel plate 1401 thereof has a thickness of 20 mm, a height of 1000 mm, and a width of 1020 mm. The embedded steel bars 1402 are HRB400 with a diameter of 10 mm. There are 16 steel bars welded in a row on each side of the steel plate. The bottom plate 1403 of the cap 14 has a thickness of 20 mm, a width of 1020 mm, and a length of 500 mm. The side plate 1404 of the cap 14 has a thickness of 20 mm.

[0099] The cross-sectional dimensions of the steel lattice column 16 are 460 mm × 460 mm. The tie material of the steel lattice column 16 is long angle steel, the long angle steel is L140 × L14, the tie plate thickness is 10 mm, the height is 400 mm, the width is 460 mm, and the tie plate spacing is 600 mm.

[0100] The pallet 15 is 20 mm thick, 860 mm wide and 1860 mm long. A right-angle triangular steel plate is welded under the pallet 15. One side of the steel plate is welded to the pallet 15, and the other side is welded to the steel lattice column 16. The thickness of the steel plate is 20 mm.

[0101] The adjustment system includes 4 mid-beam adjustment systems, using a total of 12 jacks 4, and a 500-ton hydraulic jack 4 is selected; the mid-beam adjustment system includes a retaining steel structure 5 and a jack 4, and the 20 main supports are connected into 10 rows of main supports through 4 adjustment systems. From west to east, there are three rows of main supports sharing the retaining steel structure 5, two rows of main supports sharing the retaining steel structure 5, two rows of main supports sharing the retaining steel structure 5, and three rows of main supports sharing the retaining steel structure 5.

[0102] The mid-beam adjustment system includes a force-retaining steel structure 5 and a jack 4 placed on the force-retaining steel structure 5; the beam end adjustment system includes a force-retaining head 1406, a gasket 1407 and a jack 4 placed on the pedestal 14 arranged at one end of the main support, the gasket 1407 is 10mm thick, and the gasket is 1000mm high and 1000mm wide. The force-retaining steel structure 5 is composed of a part A 501, a part B 502, a steel sheet 503, an insert ring 504, and an insert plate 505; the part A 501 is formed by welding two long steel plates with a length of 11000mm, a height of 1000mm, and a thickness of 20mm and a steel partition with a length of 1000mm, a height of 1000mm, and a thickness of 20mm, and the two long steel plates are welded and connected by a steel partition perpendicular to the long steel plates; wherein, a connecting plate with a length of 500mm, a height of 1000mm, and a thickness of 20mm is welded on one side of a long steel plate, and the connecting plate has two rows of six No. 3 holes 501-1, and the No. 3 holes 501-1 are adapted to the transverse screw holes 105; a force-retaining box 501-2 is welded on one side of the other long steel plate, and the force-retaining box 501-2 is formed by welding a steel plate with a height of 1000mm, and a thickness of 20mm; the part B 502 is formed by welding two long steel plates with a length of 11000mm, a height of 1000mm, and a thickness of 20 The two long steel plates are welded together by a steel partition plate that is 1000mm long, 1000mm high and 20mm thick. The two long steel plates are connected by welding a steel partition plate that is perpendicular to the long steel plates. A connecting plate that is 500mm long, 1000mm high and 20mm thick is welded on one side of one long steel plate. There are two rows of six No. 4 holes 502-1 on the connecting plate. The No. 4 holes 502-1 are matched with the transverse screw holes 105. A jack 4 support 502-2 and a protruding steel plate 502-3 that is 500mm long, 1000mm wide and 20mm thick are welded on one side of the other long steel plate. The jack 4 support 502-2 is formed by welding a 20mm thick semicircular steel plate on the long steel plate; insert rings 504 are welded on the side surfaces of the two end heads of part A 501 and part B 502, totaling 12, and insert plates 505 with a cross-sectional size of 100mm×20mm are inserted into the insert rings 504.

[0103] Each row of main supports in the axial bracing is formed by axially connecting 14 steel-concrete beam segments 1, and both ends of each row of main supports are placed on the cap 14.

[0104] A steel plate with a thickness of 20 mm and a width of 100 mm is selected for welding to form a hoop 20 , which fixes the main support on the pallet 15 . One end of the hoop 20 is welded to the pallet 15 , and the other end is welded to the steel lattice column 16 .

[0105] In each inner support, there are 72 steel structure auxiliary supports 2 connecting the adjacent main supports, and there are 16 steel structure S-beams.

[0106] The steel structure auxiliary support 2 used for connecting adjacent main supports is formed by welding a frame 201 and an end plate 202; the frame 201 is a circular steel tube with a diameter of 500 mm and a wall thickness of 20 mm; the end plate 202 is a steel plate, on which two rows of No. 1 holes 202-1 for connection are provided, the aperture of the No. 1 hole 202-1 is 30 mm, the row spacing between the two rows of No. 1 holes 202-1 is 720 mm, and the No. 1 hole 202-1 is compatible with the transverse screw hole 105.

[0107] The steel structure auxiliary support 2 used for the steel structure S-beam is formed by welding a frame 201 and an end plate 202; the frame 201 is an H-shaped steel, and the model of the H-shaped steel is H600mm×600mm; the end plate 202 is a steel plate, on which two rows of No. 1 holes 202-1 for connection are arranged, the aperture of the No. 1 hole 202-1 is 30mm, and the row spacing between the two rows of No. 1 holes 202-1 is 720mm.

[0108] The cross-sectional width of the steel-concrete beam section 1 is 1000 mm, the cross-sectional height is 1000 mm, and the length is 5 m. The end of the steel-concrete beam section 1 is provided with two rows of six vertical screw holes 104 (three holes in each row), two columns of six transverse screw holes 105 (three holes in each column), and two columns of four longitudinal rebar holes 103 (two holes in each column). In the middle part of the rectangular reinforced concrete 102, symmetrically to the middle section of the steel-concrete beam section 1, two rows of six inclined cable holes 106 (three in each row) are arranged.

[0109] The hole plane layout of the vertical screw hole 104 is a rectangular hole layout with a hole diameter of 30mm, a row spacing of 200mm, a hole spacing of 300mm, a distance from the outermost row of holes to the end face of 250mm, and a distance from the outermost hole in each row of holes to the adjacent end side of 200mm.

[0110] The hole plane layout of the transverse screw holes 105 is a rectangular hole layout with a hole diameter of 30mm, a row spacing of 240mm, a hole spacing of 300mm, a distance of 120mm from the outermost row of holes to the end face of the steel-concrete beam section 1, and a distance of 200mm from the uppermost hole in each row of transverse screw holes 105 to the upper surface.

[0111] The hole opening plane layout of the longitudinal reinforcement holes 103 is a rectangular hole layout, with a hole diameter of 40mm, a hole depth of 500mm, a row spacing of 400mm, a hole spacing of 400mm, a distance from the top hole to the upper surface of 300mm, and a distance from the left hole to the left side of the steel-concrete beam section 1 of 300mm.

[0112] The hole diameter of the cable-stayed hole 106 is 30 mm, the inclination angle is 45°, the hole openings are arranged in a rectangular pattern on the upper surface of the steel-concrete beam section 1, the hole spacing is 300 mm, the row spacing is 1000 mm, and the distance from the hole openings of each row of holes on the upper surface of the steel-concrete beam section 1 to the end face of the adjacent steel-concrete beam section 1 is 2000 mm, and the distance from the outermost holes of each row to the side face of the adjacent steel-concrete beam section 1 is 200 mm.

[0113] A steel plate with a size of 800mm×500mm×10mm is selected as the upper and bottom steel plates of the beam sleeve 101. The diameter, row spacing and hole spacing of the holes on it are the same as those of the vertical screw holes 104. The edge of the steel plate with a length of 500mm is welded to the angle steel. A steel plate with a size of 800mm×500mm×10mm is selected as the side steel plate of the beam sleeve 101. The diameter, row spacing and hole spacing of the holes on it are the same as those of the transverse reinforcement holes 105. The edge of the steel plate with a length of 500mm is welded to the angle steel. An angle steel with a model of L100×10 and a length of 5m is selected as the angle steel of the beam sleeve 101.

[0114] The structure of the axial node is as follows: the end faces of the two steel-concrete beam sections 1 are closely fitted, and a connecting steel plate 12 with a length of 1000mm, a width of 1000mm and a thickness of 20mm is provided on each span of the upper and lower surfaces of the fitting, and four rows of twelve No. 6 holes 1201 are opened on the connecting steel plate 12, and the hole diameter of the No. 6 hole 1201 is 30mm, and the hole diameter of the No. 6 hole 1201 is 30mm, which is compatible with the vertical screw hole 104, and the longitudinal dowel holes 103 on the end faces of the two steel-concrete beam sections 1 are aligned one by one and inserted with round steel 6; The diameter of the round steel 6 is 34 mm; the thickness of the connecting steel plate 12 is 20 mm, the width is 1000 mm, and the length is 1000 mm; the diameter of the horizontal tension screw 8 is 24 mm; and the diameter of the vertical tension screw 7 is 24 mm.

[0115] The inclined cable adjuster 13 is composed of an adjuster base plate 1301, an adjusting screw 1302, an adjuster support rod 1303, a web 1304, a left-handed nut 1305, a fixing piece 1306, a right-handed nut 1307, and a pin 1308; the adjuster base plate 1301 of the inclined cable adjuster 13 is 1000mm long, 1000mm wide, and 20mm thick. There are two rows of six No. 2 holes 1301-1 on the adjuster base plate 1301. The aperture of the No. 2 hole 1301-1 is 30mm and is compatible with the vertical screw hole 104. Two fixing pieces 1306 are welded on the web 1304 and the adjusting base plate 1301. The web 1304 is 20mm thick. Each fixing piece 1306 is welded on the web 1304. There are two pins 1308 on the joint 1306, and the two pins 1308 are connected to two adjuster support rods 1303, the diameter of the adjuster support rods 1303 is 30 mm, and the other ends of the two adjuster support rods 1303 are respectively connected to a right-handed nut 1307 and a left-handed nut 1305 through the pins 1308. There is a handle 1302-3 at the end of the adjusting screw 1302, and the diameter of the adjusting screw 1302 is 40 mm. Two groups of positive and negative threads are arranged on the adjusting screw 1302, and each group of positive and negative threads includes a right-handed thread 1302-1 and a left-handed thread 1302-2; each group of positive and negative threads is equipped with a right-handed nut 1307 and a left-handed nut 1305.

[0116] The No. 1 hole 202-1 of one end plate 202 of the steel structure S-beam is aligned one by one with the transverse screw hole 105 at the axial node position on the steel-concrete beam section 1 close to the foundation pit wall, and a transverse tension screw 8 is inserted therein, and both ends of the transverse tension screw 8 are fixed with nuts 10; the other end plate 202 of the steel structure S-beam is fixed to the crown beam 17 or the waist beam 18 with bolts 21.

[0117] One side of the axial node is connected to a steel structure auxiliary support 2, and the end plate 202 is connected to the axial node across the seam, that is, the No. 1 hole 202-1 of the end plate 202 is respectively connected to the transverse screw hole 105 on one side of the end of the two steel-concrete beam sections 1 connected at the axial node, and is fixed with a transverse tension screw 8 and a nut 10.

[0118] There is no auxiliary support connection on one side of the axial node. The side connecting steel plate 11 is installed on this side of the axial node, and the transverse tension screw 8 passes through the No. 5 hole 1101 and the transverse screw hole 105, and is fixed with a nut 10. The side connecting steel plate 11 is 1000mm high, 1000mm wide and 20mm thick. There are four rows of twelve No. 5 holes 1101 on it, and the row spacing is 240mm. The aperture of the No. 5 hole 1101 is 30mm, which is compatible with the transverse screw hole 105.

[0119] There is no auxiliary support connection on one side of the axial node. The side connecting steel plate 11 is installed on this side of the axial node, and the transverse tension screw 8 passes through the No. 5 hole 1101 and the transverse screw hole 105, and is fixed with a nut 10. The side connecting steel plate 11 is 1000mm high, 1000mm wide and 20mm thick. There are four rows of twelve No. 5 holes 1101 on it, and the row spacing is 240mm. The diameter of the No. 5 hole 1101 is 30mm.

[0120] 1. Prepare wire saw cutting machine, support frame, crane, forklift and other equipment, and arrange the location and access passage of equipment; 2. Construct the floor slab and plain concrete replacement support under the first support. After the construction of the floor slab and concrete replacement support structure under the first support is completed and the concrete reaches 80% of the design strength, remove the first support; 3. The jack 4 is extended, and the jack 4 on the beam adjustment system extends the A part 501 of the force-retaining steel structure 5, and the steel sheet is removed. The pressure of the jack 4 is reduced to 0, and the jack 4 is removed; 4. Use a cutting machine to cut the angle steel at the main support node, and then remove the steel structure auxiliary support 2 of the first support row by row; first set up a support frame under the steel structure auxiliary support 2, and then remove the nut fixing the transverse tension screw, pull out the transverse tension screw connecting the steel structure auxiliary support 2 and the steel-concrete beam section 1, unscrew the fixing bolts of the steel structure auxiliary support 2 used as the eight-shaped beam, remove the lateral connection steel plate, remove the steel structure auxiliary support 2 with a forklift, and then use a crane to transport the steel structure auxiliary support 2 out of the foundation pit; 5. Remove the first supporting steel-concrete beam section 1 row by row, and set up a support frame under the steel-concrete beam section 1; cut the cap 14 and the hoop 20 with a cutting machine; remove the transverse tension screws and nuts connecting the force-retaining steel structure 5 and the steel-concrete beam section 1, and use a forklift and a crane to transport the removed A part 501 and B part of the force-retaining steel structure 5 out of the foundation pit; remove the inclined cable 9 and the vertical tension screw 7 at the main support node, and remove the connecting steel plate 12, the inclined cable adjuster 13, and the nut 10; remove the steel-concrete beam section 1 with a forklift, and pull out the round steel 6 inserted in the longitudinal reinforcement hole 103; and then use a crane to transport the removed steel-concrete beam section 1 out of the foundation pit; 6. Set up a support frame under the corbel 19 of the crown beam of the first support; 7. Use a rope saw to cut the lower corbel 19; remove the plaster at both ends of the L-shaped pre-buried hole of the first supporting crown beam. After the cleaning is completed, insert the rope saw chain into the L-shaped pre-buried hole, turn on the rope saw cutting machine, cut the crown beam, and transport the cut crown beam section and corbel 19 out of the foundation pit with a forklift or a crane; 8. Use a wire saw cutting machine to cut the steel lattice column 16, and the cut steel lattice column 16 is transported out of the foundation pit by a crane.

[0121] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0122] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An assembled steel-concrete-steel structure foundation pit support system, comprising a crown beam (17), a waist beam (18), support piles (3) and an internal support system, characterized in that: The internal support system is composed of a plurality of main supports formed by a plurality of prefabricated steel-concrete beam sections (1), a plurality of steel structure auxiliary supports (2), a plurality of steel lattice columns (16), and an adjustment system; the steel-concrete beam sections (1) are standard parts with the same structure and size; The surface of the steel-concrete beam section (1) is provided with a beam sleeve (101), and a rectangular concrete (102) is arranged inside. A cable hole (106) is arranged inside the rectangular reinforced concrete (102); longitudinal reinforcing bar holes (103), vertical screw holes (104), and transverse screw holes (105) are arranged at both ends of the steel-concrete beam section (1), and the longitudinal reinforcing bar holes (103), vertical screw holes (104), transverse screw holes (105), and cable holes (106) do not intersect with each other; The crown beam (17) and the waist beam (18) are provided with a plurality of corbels (19), and each corbel (19) is provided with a support platform (14); the crown beam (17) and the waist beam (18) are respectively provided with an L-shaped embedded hole (1701) and an I-shaped embedded hole (1801) for wire saw cutting; Each main support is formed by axially connecting a plurality of steel-concrete beam sections (1), wherein the connection point between two steel-concrete beam sections (1) is an axial node; a plurality of steel structure auxiliary supports (2) are connected between adjacent main supports, wherein the two ends of the steel structure auxiliary supports (2) are connected to one side of two axial nodes of adjacent main supports; one side of the axial node of some main supports close to the foundation pit wall is connected to a steel structure auxiliary support (2), wherein the other end of the steel structure auxiliary support (2) is connected to the side of a crown beam (17) or a waist beam (18), wherein the steel structure auxiliary support (2) is a steel structure eight-shaped beam; The structure of the axial node is as follows: the end surfaces of the two steel-concrete beam sections (1) are tightly fitted, and a connecting steel plate (12) is provided at each span of the upper and lower surfaces of the fitting, a No. 6 hole (1201) is opened on the connecting steel plate (12), and the longitudinal reinforcing bar holes (103) on the end surfaces of the two steel-concrete beam sections (1) are aligned one by one and are inserted with round steel bars (6); The main support described above forms a row of main supports or two main supports are connected to form a row of main supports through an adjustment system, and both ends of each row of main supports are placed on a bearing platform (14); The main support is installed on the steel lattice column (16), and the contact position between the main support and the steel lattice column (16) is staggered from the axial node; a tray (15) is provided on the steel lattice column (16), and the main support is placed on the tray (15), and one side of the steel-concrete beam section (1) in the main support is closely attached to the lattice column (16); one end of a hoop (20) is welded to the tray (15), and the hoop (20) embraces the main support, and the other end is welded to the steel lattice column (16), so as to fix the main support.

2. The assembled steel-concrete-steel structure foundation pit support system according to claim 1, characterized in that: A cable adjuster (13) is provided below the axial node, and the cable adjuster (13) is composed of an adjuster base plate (1301), an adjusting screw rod (1302), an adjuster support rod (1303), a web rod (1304), a left-handed nut (1305), a fixing member (1306), a right-handed nut (1307), and a pin (1308); a second hole (1301-1) is provided on the adjusting base plate (1301); the web rod (13 04) and the adjusting base plate (1301), respectively, two fixing members (1306) are welded thereon; each of the fixing members (1306) has two pins (1308), the two pins (1308) are connected to two adjusting device support rods (1303), and the other ends of the two adjusting device support rods (1303) are respectively connected to a right-handed nut (1307) and a left-handed nut (1305) through the pins (1308); the end of the adjusting screw (1302) has a handle (1302-3), the adjusting screw (1302) is provided with two groups of positive and negative threads, each group of positive and negative threads includes a right-handed thread (1302-1) and a left-handed thread (1302-2); each group of positive and negative threads is equipped with a right-handed nut (1307) and a left-handed nut (1305); the vertical screw hole (104) at the axial node, the sixth hole (1201) on the two connecting steel plates (12) and the second hole (1301) on the inclined cable adjuster (13) -1) are coaxial and penetrated by a vertical tension screw rod (7), and nuts (10) are provided at both ends of the vertical tension screw rod (7); a cable (9) is inserted into the cable hole (106), and the cable (9) extends from the cable hole (106) of one steel-concrete beam section (1) and extends from the cable hole (106) of another adjacent steel-concrete beam section (1); both ends of the cable (9) are fixed by anchor heads (25), and the middle part is placed on the web (1304) of the cable adjuster (13).

3. The assembled steel-concrete-steel structure foundation pit support system according to claim 1 is characterized in that: The steel structure auxiliary support (2) is formed by welding a frame (201) and an end plate (202); the frame (201) is an I-beam, a steel pipe or an H-beam; the end plate (202) is a steel plate, on which a No. 1 hole (202-1) for connection is provided, and the No. 1 hole (202-1) has the same diameter and spacing as the transverse screw hole (105).

4. The assembled steel-concrete-steel structure foundation pit support system according to claim 3 is characterized in that: A No. 1 hole (202-1) of one end plate (202) of the steel structure S-shaped beam is aligned one by one with the transverse screw hole (105) at the axial node position on the steel-concrete beam section (1) close to the foundation pit wall, and a transverse tension screw (8) is inserted therein, and both ends of the transverse tension screw (8) are fixed with nuts (10); the other end plate (202) of the steel structure S-shaped beam is fixed to the crown beam (17) or the waist beam (18) with bolts (21).

5. The assembled steel-concrete-steel structure foundation pit support system according to claim 4 is characterized in that: There are three ways to connect one side of the axial node with the steel structure auxiliary support (2), the first of which is: one side of the axial node is connected to a steel structure auxiliary support (2), and the end plate (202) is connected to the axial node across the seam, that is, the No. 1 hole (202-1) of the end plate (202) is respectively connected to the transverse screw hole (105) on one side of the end of the two steel-concrete beam sections (1) connected at the axial node, and fixed with a transverse tension screw (8) and a nut (10); The second type is as follows: one side of the axial node is connected to two steel structure auxiliary supports (2), a side connection steel plate (11) is provided on one side of the axial node, the side connection steel plate (11) has four rows of No. 5 holes (1101), the span seams correspond one-to-one with the two rows of transverse screw holes (105) on the sides of the two steel-concrete beam sections (1) at the axial node, and also correspond one-to-one with the No. 1 holes (202-1) on the end plates (202) of the two steel structure auxiliary supports (2), and after the transverse tension screws (8) pass through the coaxial No. 1 holes (202-1), No. 5 holes (1101) and transverse screw holes (105), the two ends are tightened with nuts (10); The third type is as follows: there is no auxiliary support connection on one side of the axial node, the side connecting steel plate (11) is installed on this side of the axial node, and after the transverse tension screw (8) passes through the fifth hole (1101) and the transverse screw hole (105), the two ends of the transverse tension screw (8) are fixed with nuts (10).

6. The assembled steel-concrete-steel structure foundation pit support system according to claim 5, characterized in that: Angle steels (24) are welded at the four corners where the connecting steel plate (12) is connected to the side connecting steel plate (11) or at the four corners where the connecting steel plate (12) is connected to the auxiliary supporting end plate.

7. The assembled steel-concrete-steel structure foundation pit support system according to claim 1, characterized in that: The adjustment system is divided into a mid-beam adjustment system and a beam end adjustment system; the mid-beam adjustment system comprises a force-retaining steel structure (5) and a jack (4) placed on the force-retaining steel structure (5); the beam end adjustment system comprises a force-retaining head (1406), a gasket (1407) and a jack (4) arranged on a cap (14); the force-retaining steel structure (5) comprises a part A (501), a part B (502), a steel sheet (503), an insert ring (504), and an insert plate (505); the part A (501) comprises two long steel plates and a steel partition plate vertically welded between the two long steel plates The invention is composed of a connecting plate welded to one side of a long steel plate, and the connecting plate has a No. 3 hole (501-1); a force box (501-2) is welded to one side of another long steel plate, and the force box (501-2) is formed by welding steel plates; the B part (502) is composed of two long steel plates and a steel partition plate vertically welded between the two long steel plates, wherein a connecting plate is welded to one side of one long steel plate, and the connecting plate has a No. 4 hole (502-1); a jack support (502-2) and a protruding steel plate (502-3) are welded to one side of another long steel plate, and the jack The jack support (502-2) is formed by welding a semicircular steel plate to a long steel plate; the height of the long steel plate and the plurality of steel partitions is the same as the cross-sectional height of the steel-concrete beam section (1); the connecting plates are in groups of two, and the spacing between the two connecting plates is the same as the cross-sectional width of the steel-concrete beam section (1); the insert ring (504) is welded to the side surfaces of the force-retaining box (501-2) at both ends of the A part (501) and the side surfaces of both ends of the B part (502); the arrangement of the No. 3 hole (501-1) and the No. 4 hole (502-1) and the transverse screw hole (105) of the steel-concrete beam section (1) and the hole The diameters of the steel sheets (503) are the same, and the width of the steel sheet (503) is the same as the width of the force box (501-2); the force box (501-2) of part A is placed on the protruding steel plate (502-3) of part B (502), and the connection between part A (501) and part B (502) is achieved by inserting the insert plate (505) into the insert ring (504); the connection between the force-retaining steel structure (5) and the main support is achieved by making the fourth hole (502-1) on the connecting plate correspond to the transverse screw hole (105) at the end of the main support one by one, inserting the transverse tension screw (8) and tightening it with a nut (10).

8. The assembled steel-concrete-steel structure foundation pit support system according to claim 1, characterized in that: There are two types of the cap (14), one type of cap (14) is composed of a pre-embedded steel plate (1401), pre-embedded steel bars (1402), a cap bottom plate (1403), and a cap side plate (1404); the other type of cap (14) is composed of a pre-embedded steel plate (1401), pre-embedded steel bars (1402), a cap bottom plate (1403), a cap side plate (1404), a jack wooden support (1405), a force-retaining head (1406), and a gasket (1407); the force-retaining head (1406) is formed by welding an I-beam and a steel plate, the steel plate size of the force-retaining head (1406) is the same as the cross-sectional size of the steel-concrete beam section (1), the pre-embedded steel plates (1401) are all arranged at the corbels (19), and one side of the pre-embedded steel plates (1401) is welded with pre-embedded steel bars (1402).

9. The assembled steel-concrete-steel structure foundation pit support system according to claim 1, characterized in that: The L-shaped embedded holes (1701) and the I-shaped embedded holes (1801) are respectively preset in the crown beam (17) and the waist beam (18) every 3-5 m; The L-shaped embedded hole (1701) is formed by embedding an L-shaped PVC tube (22) in the crown beam (17). The L-shaped PVC tube (22) is open at both ends, one end is open on the upper surface of the crown beam (17), and the other end is open on the side of the crown beam (17). The embedded position of the L-shaped PVC tube (22) is staggered with the position of the corbel (19). The I-shaped embedded hole (1801) is formed by embedding an I-shaped PVC pipe (23) in the waist beam (18); the I-shaped PVC pipe (23) has openings at both ends, one end of the opening is located on the top surface of the waist beam (18), and the other end of the opening is located on the bottom surface of the waist beam (18); the I-shaped PVC pipe (23) is embedded on one side of the waist beam (18) close to the supporting pile (3); and the embedded position of the I-shaped PVC pipe (23) is staggered with the position of the corbel (19).

10. The method for dismantling the prefabricated steel-concrete-steel structure foundation pit support system according to claims 1 to 9 is characterized in that: The following steps are involved: 1) Prepare the wire saw cutting machine, support frame, crane, forklift and other machines and tools, and arrange the location and access channels of the machines and tools; 2) After the foundation slab is constructed, wait until it reaches 80% of the design strength, then construct the floor slab below the lowest support. After the support is replaced, prepare to remove the lowest support; 3) The jack (4) is extended, the jack (4) on the beam adjustment system extends the A part (501) of the force-retaining steel structure (5), and the jack (4) on the beam end adjustment system extends the force-retaining head (1406); the gasket (1407) and the steel sheet (503) are removed, the pressure of the jack (4) is reduced to 0, and the jack (4), the force-retaining head (1406) and the jack wooden support (1405) are removed; 4) Use a cutting machine to cut the angle steel (24) at the axial node of the main support; remove the steel structure auxiliary support (2) of the lowest support: after setting up a support frame under the steel structure auxiliary support (2), loosen the nut (10), remove the transverse tension screw rod (8) and bolt (21), remove the side connection steel plate (11), and then use a forklift or crane to transport the steel structure auxiliary support (2) out of the foundation pit; 5) Dismantle the steel-concrete beam sections (1) of all the main supports of the lowest support row by row: start dismantling each row of main supports from the pedestal with jacks (4) or from the retaining steel structure (5), set up a support frame under the steel-concrete beam section (1) to be dismantled, and use a cutting machine to cut the pedestal (14) and the hoop (20); remove the transverse tension screws (8) and nuts (10) connecting the retaining steel structure (5) and the steel-concrete beam section (1), pull out the plug plate (505) in the plug ring (504), and dismantle the A part (501) and the retaining steel structure (5). B part (502); use a forklift and a crane to transport the dismantled A part (501) and B part (502) of the bracing steel structure (5) out of the foundation pit; loosen the anchor heads (25) at both ends of the inclined cable (9), pull out the inclined cable (9) and the vertical tension screw (7) at the axial node of the main support, and remove the connecting steel plate (12) and the inclined cable adjuster (13); use a forklift to pull out the steel-concrete beam section (1) from the axial node one by one along the axial direction, and then pull out the connecting round steel (6); use a crane to transport the dismantled steel-concrete beam section (1) out of the foundation pit; 6) A support frame is set up below the lowermost supporting waist beam (18) and its upper corbel (19); 7) Use a rope saw to cut the corbel (19); after clearing the I-shaped pre-buried hole (1801) of the lowermost supporting waist beam (18), insert the rope saw chain into the I-shaped pre-buried hole (1801), start the rope saw cutting machine, and cut the waist beam (18); the cut waist beam section and corbel (19) are transported out of the foundation pit by a forklift or a crane; 8) Repeat steps 2) to 7) to complete the removal of all non-first support; 9) Construct the floor slab below the first support, and after replacing the support, prepare to remove the first support; 10) Repeat steps 3), 4), and 5) to complete the removal of the main support, steel structure auxiliary support (2), and adjustment system of the first internal support system; 11) A support frame is set up under the corbel (19) of the crown beam (17) of the first support; 12) Use a wire saw to cut the corbel (19); after clearing the L-shaped pre-buried hole (1701) of the first supporting crown beam (17), insert the wire saw chain into the L-shaped pre-buried hole (1701), start the wire saw cutting machine, cut the crown beam (17), and transport the cut crown beam section and corbel (19) out of the foundation pit by forklift or crane; 13) The steel lattice columns (16) are cut using a cutting machine, and the cut steel lattice columns (16) are transported out of the foundation pit using a crane.

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