Trestle structure for hexagonal deep foundation pit complex environment construction and earthwork construction method

Abstract

The invention discloses a trestle structure for hexagonal deep foundation pit complex environment construction and an earthwork construction method. The trestle structure comprises an annular trestle, stand columns which are arranged in the annular direction of the annular trestle at equal intervals and support the annular trestle, channel steel connecting rods connected between the stand columns, and supporting beams connected with joints of the tops of the stand columns. A formwork frame body of the annular trestle is composed of transverse rods, vertical rods, spherical joints, adjustable supporting supports, adjustable bases, bottom formworks, bottom formwork battens, side formworks, opposite-pull screws and side formwork battens. Connecting plates are arranged on the side faces of the stand columns, and stressed steel bars of the supporting beams are connected with the connecting plates in a welded mode. The trestle structure and the inner support are constructed synchronously, the construction speed is high, the annular trestle serves as a transportation channel and can also serve as a material storage yard, a vehicle staggering point, a machining area and an earthwork temporary loading point, and the utilization rate is high; the earth excavation mode is flexible, diversified construction machines can be configured, the degree of freedom of the operation space of the construction machines is large, and the device is suitable for construction in a narrow and complex environment system.

Description

Technical Field

[0001] The invention relates to the technical field of building construction, and in particular to a trestle structure and an earthwork construction method for construction in a complex environment of a hexagonal deep foundation pit. Background Art

[0002] With the rapid development of my country's economy and the acceleration of urbanization, urban land is becoming increasingly scarce, land prices are gradually rising, and land utilization is getting higher and higher. The scale of urban ground and underground space development is getting larger and larger. Some super-high-rise basements have as many as several floors, with a large amount of earth excavation. In addition, the underground rail transit lines, pipelines and surrounding environment are complex, the construction area is small, the construction is difficult, and the safety risks are high, which brings great challenges to the construction.

[0003] In the complex environment system of a small space, it is difficult to arrange the temporary roads, earthwork yards, processing yards, material component yards and construction machinery sites that are supporting the construction. At present, under the deep foundation pit support system, the traditional pit trestle has shortcomings. It is repaired while digging, and is greatly affected by the progress of earthwork excavation. During the main construction, part of the trestles need to be dismantled before the main structure can be constructed, which makes the construction complicated. The traffic organization of the pit trestle is single, and it has high requirements on the width, thickness, load, slope, etc. of the trestles, and it also has great restrictions on the earthwork excavation method; in addition to the internal support columns, the pit trestle also needs to increase the arrangement of columns of different elevations consistent with the slope, which has high construction costs.

[0004] In the complex environmental system of a small space, the traditional symmetrical support + pit trestles are difficult to meet the layout requirements of temporary roads, earthwork yards, processing yards, material and component yards, and construction machinery sites required for construction. Summary of the invention

[0005] Based on the deficiencies in the above-mentioned prior art, the technical problem to be solved by the present invention is to provide a trestle structure and an earthwork construction method for the construction of a hexagonal deep foundation pit in a complex environment. The trestle is constructed synchronously with the internal support, and the construction speed is fast. The circular trestle can be used as a transportation channel, and can also be used as a material yard, staggered vehicle, processing area and temporary earthwork loading point, with a high utilization rate. The earthwork excavation method is flexible, and a variety of construction machinery can be configured, and the construction machinery has a large degree of freedom in the working space. The circular trestle + flexible earthwork excavation method is more suitable for construction in narrow and complex environment systems.

[0006] In order to achieve the above-mentioned purpose, the present invention adopts the following technical measures:

[0007] A trestle structure for construction in a complex environment of a hexagonal deep foundation pit comprises a ring-shaped trestle, columns arranged at equal intervals along the circumference of the ring-shaped trestle and supporting the ring-shaped trestle, channel steel connecting rods connected between the columns, and support beams connected to nodes at the tops of the columns; the formwork frame of the ring-shaped trestle consists of cross bars, vertical bars, spherical nodes, adjustable supports, an adjustable base, a bottom form, bottom form wood, side forms, tension screws and side form wood; connecting plates are provided on the sides of the columns, and the force-bearing steel bars of the support beams are connected to the connecting plates by welding.

[0008] Preferably, the crossbar, vertical pole, spherical node, adjustable support and adjustable base are provided with bolt threads, which are connected to form an integral formwork support frame through the bolt threads. As a safety measure to prevent the formwork frame from falling as a whole, the steel bars hold the lower spherical nodes and are welded to the bottom reinforcement of the annular trestle.

[0009] Furthermore, the columns and the channel steel connecting rods are continuously cross-arranged, and the oblique connecting rods, the transverse connecting rods and the columns of the channel steel connecting rods form an isosceles right triangle.

[0010] Furthermore, the annular trestle is high in the middle and low on both sides, and has drainage holes on the edges. The edges of the annular trestle are provided with anti-ridges, and protective railings are provided on the anti-ridges.

[0011] Preferably, the columns of the annular trestle are arranged at a spacing of 6m to 9m; the drainage holes on the edge of the annular trestle are symmetrically arranged about the center line of the annular trestle, with a spacing of 6m to 9m, staggered from the positions of the columns, and the diameter of the drainage holes is 30mm to 50mm.

[0012] Furthermore, seven plates with the same thickness as the circular trestle are evenly arranged around the circular trestle. In addition to being used as a staggered vehicle and temporary earthwork yard, it can also be used as a template and processing area, a machinery and equipment storage area, a concrete pump truck station, a scaffolding support yard, a steel structure yard, a steel bar and processing area, and a ramp.

[0013] Accordingly, the earthwork construction method for a hexagonal deep foundation pit in a complex environment of the present invention comprises the following steps:

[0014] S1. Earthwork excavation plane and vertical construction section division; Earthwork excavation plane construction section division The radial direction of the earthwork excavation plane is divided into four parts with the center point of the foundation pit as the center of the circle. The innermost part is a circle, the two middle parts are concentric rings, and the outermost part is formed by the foundation pit edge line and the outer edge line of the third ring; The chord direction takes the center point of the foundation pit as the center of the circle and 45° as the basic unit array to divide the entire foundation pit plane into 8×3+1=25 areas. The two mirror excavation areas form central symmetry with the center point of the foundation pit to facilitate symmetrical excavation. From outside to inside, they are: A1, A1', A2, A2', A3, A3', A4, A4', B1, B1', B2, B2', B3, B3', B4, B4', C1, C1', C2, C2', C3, C3', C4, C4', D;

[0015] S2. Excavate the first stage of earthwork, excavate to the bottom of the crown beam of the first internal support, and construct the first internal support; excavate the earthwork symmetrically, layered, and segmented from the top of the foundation pit to the crown beam and the bottom of the first internal support; excavate the first stage of earthwork, excavate from the top of the foundation pit to the crown beam and the bottom of the first internal support, and the excavation operation shall be carried out in accordance with the principles of zoning, segmentation, layering, symmetry, time limit, balanced excavation, and strict prohibition of over-excavation; the first stage of earthwork adopts the central island excavation, and the excavation order is as follows: excavate the area far away from the gate first, and then the area close to the gate. Excavate the area behind the gate, excavate backwards, and end with the horseway; the muck truck enters from the 2# gate at the southeast corner of the foundation pit and exits from the 1# gate at the southwest corner of the foundation pit. The excavation sequence is: A1A1'→A2A2'→A3A3'→A4→B1B1'→B2B2'→B3B3'→B4→C1C1'→C2C2'→C3C3'→C4→D→C4'→B4'→A4', then install the tower crane, and construct the first inner support according to the design drawings. The tower crane hoists the materials required for the inner support construction;

[0016] S3. When the concrete strength of the first inner support reaches the design strength, the second stage of excavation is carried out to the bottom of the waist beam of the second inner support, and the second inner support is constructed; excavation is carried out from the bottom of the first inner support to the waist beam and the bottom of the second inner support. The excavation method is similar to the first stage. The overall excavation method is the center island type. The area far from the gate is excavated first, and then the area near the gate is excavated, and finally the horseway is finished; earthwork vehicles enter from Gate 2#, pass the circular trestle under the ramp, and then enter through the horseway In the foundation pit, the muck trucks filled with earth pass through the circular trestle on the horseway, then through the road on the ramp, and finally transported out through Gate 1#. The excavation sequence is: A1A1'→A2A2'→A3A4→B1B1'→B2B2'→B3B4→C1C1'→C2C2'→C3C3'→C4→D→C4'→B3'B4'→A3'A4', then the formwork support of the first inner support is removed, and then the second inner support is constructed according to the design drawings;

[0017] S4. When the concrete strength of the second inner support reaches the design strength, the third stage of earthwork is excavated to the bottom of the foundation slab and cushion layer. When excavating the third stage of earthwork, the formwork support of the second inner support is removed at the same time, and the excavation is carried out from the bottom of the second inner support to the bottom of the slab. The earthwork excavation adopts the form of vertical excavation, and the composite excavation method combining the center island + basin is adopted as the whole. The earthwork at the bottom of the circular trestle and the inner support is first excavated by an excavator, and then transferred to the grab shovel operation range by a scraper, and the earth is vertically taken by the grab shovel on the circular trestle; then the earthwork in the center area is excavated by an excavator. , and then transferred to the shovel operation range by the scraper, and vertically taken soil by the shovel on the circular trestle, and finally excavated the earth in the area near the circular trestle; the muck truck enters from Gate 2#, passes the circular trestle under the ramp, moves counterclockwise, and waits for loading at the shovel. After the muck truck is full of earth, it passes the ramp on the road and exits through Gate 1#. The order of earth excavation is: A1A1'→A2A2'→A3A3'→A4A4'→C1C1'→C2C2'→C3C3'→C4C4'→B1B1'→B2B2'→B3B3'→B4B4';

[0018] S5. Excavate the fourth stage of earthwork, excavate the elevator shaft, pedestal and water collection well, cast the cushion layer and bottom plate in time, use the grab shovel on the circular trestle to vertically take soil, first excavate the earthwork at the bottom of the circular trestle and the inner support, then excavate the earthwork in the central area, and finally excavate the earthwork in the area near the circular trestle. After the earthwork excavation in the corresponding area is completed, cast the bottom plate in time. The traffic organization of earthwork vehicles is the same as the third stage. Concrete mixer trucks and concrete pump trucks enter from Gate 2#. Pass the circular trestle under the ramp, move counterclockwise, stop at the passing platform, and start concrete pouring. After the concrete mixer truck finishes pouring concrete, it goes through the road on the ramp and finally transports it out through Gate 1#. The specific earth excavation sequence is: A1A1'→A2A2'→A3A3'→A4A4'→C1C1'→C2C2'→C3C3'→C4C4'→B1B1'→B2B2'→B3B3'→B4B4'.

[0019] Through the above technical measures: the trestle with annular inner support of the present invention has a better stress state than the traditional symmetrical support, and the construction machinery and vehicles working on the trestle are relatively safe; the construction is synchronized with the inner support, and the construction speed is fast; the annular trestle can be used as a transportation channel, and can also be used as a material yard, staggered vehicle, processing area and temporary earthwork loading point, with high utilization rate; the earthwork excavation method is flexible, and a variety of construction machinery can be configured, and the construction machinery has a large degree of freedom in the working space. In comparison, the annular trestle + flexible earthwork excavation method has outstanding advantages and is more suitable for construction in narrow and complex environment systems.

[0020] Compared with the prior art, the trestle structure and earthwork construction method for complex environment construction of hexagonal deep foundation pit of the present invention have at least the following beneficial effects:

[0021] 1. Aiming at the narrow and complex hexagonal construction environment, the present invention adopts a circular trestle as a multifunctional platform for heavy-load earth transport vehicles, concrete mixer transport vehicles to pass, pass each other, large machinery sites and temporary materials and earth yards, which overcomes many difficulties brought by the narrow and complex environment to the construction, such as limited site, inability to form a loop, lack of yards, etc., improves the efficiency of earth excavation and transportation, efficiently organizes traffic, and effectively shortens the construction period.

[0022] 2. The trestle structure provided by the present invention has columns arranged at equal intervals along the circumference of the trestle, with a spacing of 6m to 9m. The channel steel reinforcement system adopts a non-continuous arrangement method of one every other. The oblique and transverse connecting rods and the columns form an isosceles right triangle. While the force is evenly distributed, the economy of the modulus of the channel steel connecting rod material is taken into account, and it is convenient for the construction of earth-moving machinery under the trestle.

[0023] 3. The multifunctional heavy-load trestle of the present invention can adopt a variety of excavation methods such as basin type, center island type and basin type + center island type composite; under this flexible earth excavation method, a variety of construction machinery such as grab shovel, front shovel, back shovel, long arm excavator and sliding arm excavator can be configured, which greatly improves the efficiency of earth excavation and effectively shortens the construction period of earth excavation.

[0024] 4. The earth excavation plane of the present invention is equally divided with the center point of the foundation pit as the center of the circle, and the mirror excavation area forms central symmetry with the center point of the foundation pit. The symmetrical excavation area is completed, which provides a working surface for the block construction of the trestle concrete jump warehouse, and the concrete is poured symmetrically immediately. The symmetrical unloading (earth excavation) and loading (concrete pouring) effectively ensure the safety of the foundation pit construction, and also ensure the connection of the working procedures, balanced resource investment, and conducive to construction management.

[0025] 5. The method for erecting and dismantling formwork supports in limited spaces provided by the present invention is convenient and can be reused, which is green and environmentally friendly. It can not only facilitate construction workers to operate in limited spaces, but also effectively improve the efficiency of erecting and dismantling formwork supports, speed up the turnover efficiency of formwork supports, save construction costs, and has good on-site construction operability. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The drawings described herein are used to provide further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute improper limitations on the present application.

[0027] Figure 1 It is a three-dimensional schematic diagram of the hexagonal deep foundation pit trestle of the present invention;

[0028] Figure 2 It is a three-dimensional schematic diagram of a part of the hexagonal deep foundation pit trestle of the present invention;

[0029] Figure 3 It is a plan view of the arrangement of the columns and the channel steel connecting rods of the hexagonal deep foundation pit trestle of the present invention;

[0030] Figure 4 It is a cross-sectional view of the columns and channel steel connecting rods of the hexagonal deep foundation pit trestle of the present invention;

[0031] Figure 5 It is a cross-sectional view of the hexagonal deep foundation pit trestle of the present invention;

[0032] Figure 6 It is a schematic diagram of the node connection of the support beam, the stress-bearing steel bars and the columns of the present invention;

[0033] Figure 7 It is a three-dimensional schematic diagram of the bottom of the first inner support of the deep foundation pit of the present invention;

[0034] Figure 8 It is a schematic diagram of a template support supported in a deep foundation pit of the present invention;

[0035] Fig. 9 It is a cross-sectional view of the formwork support and the steel bars of the safety measure for preventing the formwork from falling of the present invention;

[0036] Fig.10 It is a plan view of the formwork support supported in the deep foundation pit of the present invention;

[0037] Fig.11 It is a planar construction section division diagram for deep foundation pit earthwork excavation of the present invention;

[0038] Fig.12 It is a vertical construction section division diagram of deep foundation pit earthwork excavation of the present invention;

[0039] Fig.13 It is one of the three-dimensional schematic diagrams of the excavation of the deep foundation pit stage 1 earthwork (first stage earthwork) of the present invention;

[0040] Fig.14 This is the second three-dimensional schematic diagram of the excavation of the deep foundation pit stage 1 earthwork (first stage earthwork) of the present invention;

[0041] Fig.15 It is a cross-sectional view of the excavation of the deep foundation pit stage 1 earthwork (first stage earthwork) of the present invention;

[0042] Fig.16 It is one of the three-dimensional schematic diagrams of the deep foundation pit stage 2 earthwork (second stage earthwork) excavation of the present invention;

[0043] Fig.17This is the second three-dimensional schematic diagram of the excavation of the deep foundation pit stage 2 earthwork (second stage earthwork) of the present invention;

[0044] Fig.18 It is a cross-sectional view of the excavation of the deep foundation pit stage 2 earthwork (second stage earthwork) of the present invention;

[0045] Fig.19 It is one of the three-dimensional schematic diagrams of the excavation of the deep foundation pit stage 3 earthwork (third stage earthwork) of the present invention;

[0046] Fig. 20 This is the second three-dimensional schematic diagram of the excavation of the deep foundation pit stage 3 earthwork (third stage earthwork) of the present invention;

[0047] Fig.21 It is a cross-sectional view of the excavation of the deep foundation pit stage 3 earthwork (third stage earthwork) of the present invention;

[0048] Fig. 22 It is one of the three-dimensional schematic diagrams of the excavation of the deep foundation pit stage 4 earthwork (the fourth stage earthwork) of the present invention;

[0049] Fig.23 This is the second three-dimensional schematic diagram of the excavation of the deep foundation pit stage 4 earthwork (the fourth stage earthwork) of the present invention;

[0050] Fig.24 It is a cross-sectional view of the excavation of the deep foundation pit stage 4 earthwork (fourth stage earthwork) of the present invention;

[0051] Fig.25 The present invention is a schematic diagram of traffic guidance for a hexagonal deep foundation pit trestle.

[0052] In the figure: 1-inner support, 2-annular trestle, 3-formwork and processing area, 4-machinery storage area, 5-concrete pump truck station, 6-scaffolding support yard, 7-steel component yard, 8-rebar and processing area, 9-ramp, 10-counter-slope, 11-drainage hole, 12-column, 13-channel steel connecting rod, 14-first inner support, 15-second inner support, 16-support beam, 17-connecting plate, 18-stressed steel bar, 19-crown beam, 20-adjustable base, 21-cross bar, 22-upright pole, 23-spherical node, 24-adjustable support, 25-earthwork, 26-cushion, 27-bolt thread, 28-safety measure steel bar, 29-bottom form, 30-bottom form wood, 3 1- tensioning screw, 32- side form wood, 33- side form, 34- first stage earthwork, 35- second stage earthwork, 36- third stage earthwork, 37- fourth stage earthwork, 38- water collection well, 39- elevator shaft, 40- excavator, 41- muck truck, 42- grab shovel (long arm excavator), 43- horseway, 44- scraper, 45- concrete mixer truck, 46- concrete pump truck, 47- pedestal, 48- bottom plate, 49- guardrail, 50- tower crane, 51- load limit sign, 52- speed limit sign, 53- center line sign, 54- side line sign, 55- machinery station, 56- bottom-drop CSM water-cutting curtain, 57- underground continuous wall, 58- three-axis mixing pile. DETAILED DESCRIPTION

[0053] The following is a detailed description of the specific embodiments of the present invention in conjunction with the accompanying drawings, which is a part of this specification and illustrates the principles of the present invention through examples. Other aspects, features and advantages of the present invention will become clear from the detailed description. In the referenced drawings, the same or similar components in different figures are represented by the same reference numerals.

[0054] Next, combine Figures 1 to 25 The present invention introduces in detail the trestle structure and earthwork construction method for complex environment construction of a hexagonal deep foundation pit.

[0055] The purpose of the invention is to invent a trestle structure and earthwork construction method for complex environment construction of a hexagonal deep foundation pit in view of the complex environment around the foundation pit and the actual situation of narrow site.

[0056] The trestle structure for complex environment construction of a hexagonal deep foundation pit of the present invention comprises a circular trestle 2, columns 12 arranged at equal intervals along the circular trestle 2 and supporting the circular trestle 2, channel steel connecting rods 13 connected between the columns 12, and support beams 16 connected to nodes at the tops of the columns 12.

[0057] In the plane layout of the circular trestle 2, the plane shape of the deep foundation pit tends to be hexagonal, the columns 12 are arranged at equal intervals along the circumferential direction of the circular trestle 2, and a number of plate strips with the same thickness as the circular trestle 2 are evenly arranged around the circular trestle 2. The channel steel connecting rods 13 of the reinforcement system between the columns 12 supporting the circular trestle 2 are arranged non-continuously in the horizontal direction.

[0058] In the elevation arrangement of the circular trestle 2, the circular trestle 2 is high in the middle and low on both sides, with drainage holes 11 on the edge, a counter-step 10 on the edge of the circular trestle 2, and a guardrail 49 on the counter-step 10. The circular trestle 2 is supported in the vertical direction by a continuous cross arrangement of columns 12 and channel steel connecting rods 13, and the oblique connecting rods, transverse connecting rods and columns 12 of the channel steel connecting rods 13 form an isosceles right triangle;

[0059] The node structure of the circular trestle 2 is at the node between the support beam 16 and the column 12. A connecting plate 17 is provided on the side of the column 12. The stress-bearing steel bars 18 of the support beam 16 are connected to the connecting plate 17 by welding. The connecting plate 17 on the side of the column 12 is C-shaped.

[0060] The formwork frame of the circular trestle 2 is composed of a plurality of crossbars 21, vertical poles 22, spherical nodes 23, adjustable supports 24, adjustable base 20, bottom mold 29, bottom mold wood 30, side mold 33, tension screws 31 and side mold wood 32. The crossbars 21, vertical poles 22, spherical nodes 23, adjustable supports 24 and adjustable base 20 are provided with bolt threads 27, and are connected to form an integral formwork support frame through the bolt threads 27; the steel bars 28, which are safety measures to prevent the formwork frame from falling as a whole, hold the spherical nodes 23 at the bottom and are welded to the bottom reinforcement of the plate of the circular trestle 2.

[0061] The columns 12 of the circular trestle 2 are arranged at intervals of 6m to 9m; the drainage holes 11 on the edge of the circular trestle 2 are symmetrically arranged about the center line of the circular trestle 2, with intervals of 6m to 9m, staggered from the positions of the columns 12, and the apertures of the drainage holes 11 are 30mm to 50mm.

[0062] Based on the above-mentioned trestle structure, the earthwork construction method of the hexagonal deep foundation pit complex environment of the present invention comprises the following steps:

[0063] 1) Earthwork excavation plane and vertical construction section division;

[0064] 2) Excavating the first stage earthwork 34, excavating to the bottom of the crown beam 19 of the first inner support 14, and constructing the first inner support 14;

[0065] 3) When the concrete strength of the first inner support 14 reaches the design strength, excavate the second stage earthwork 35 to the bottom of the waist beam of the second inner support 15, and construct the second inner support 15;

[0066] 4) When the concrete strength of the second inner support 15 reaches the design strength, excavate the third stage earthwork 36 to the foundation slab 48 and the bottom of the cushion layer;

[0067] 5) Excavate the fourth stage earthwork 37, excavate the elevator shaft 39, the pedestal 47 and the water collection well 38, and pour the cushion layer and the bottom plate 48 in time.

[0068] The plane construction section of earth excavation is equally divided with the center point of the foundation pit as the center of the circle, and the mirror excavation area is centrally symmetrical with the center point of the foundation pit; the vertical construction section of earth excavation is divided into vertical stages with the number of internal support layers as the segmentation line.

[0069] The circular trestle 2 serves as a multifunctional platform for heavy-load earth transport vehicles, concrete mixer transport vehicles 45 to pass, pass each other, large machinery sites and temporary material and earth storage yards.

[0070] The present invention utilizes a multifunctional heavy-loaded circular trestle, and the earthwork can be excavated in a variety of ways, such as a basin type, a center island type, and a composite basin type + center island type; in this flexible earthwork excavation method, a variety of construction machinery such as a grab shovel, a front shovel, a back shovel, a sliding arm excavator, and a grab shovel can be configured. Using the multifunctional heavy-loaded circular trestle, the sliding arm excavator or the grab shovel 42 can vertically excavate the thick soil layer in the foundation pit on the circular trestle 2. Using the multifunctional heavy-loaded circular trestle as a temporary earthwork loading point, the earthwork excavation time is not limited, and uninterrupted continuous excavation day and night can be achieved.

[0071] The traffic organization is efficient. A number of vertical earth-moving machines and concrete pouring machines are evenly arranged on the trestle. Earth-moving and concrete mixing transport vehicles run regularly on the circular trestle 2, and enter and exit in an orderly manner.

[0072] Example

[0073] The plane shape of a deep foundation pit tends to be hexagonal. It is 38m away from Rail Transit Line 3 on the northwest side, 25m away from Rail Transit Line 2 on the northeast side, 15m away from the foundation pit of the project under construction on the southeast side, 13m away from the foundation pit of the project under construction on the southwest side, and about 18m away from the drainage corridor on the north side. The construction conditions are extremely narrow and complex. The outermost side of the foundation pit is the enclosure structure, which is a combination of a drop-down CSM water-cutting curtain 56, an underground continuous wall 57 and a three-axis mixing pile 58. Two reinforced concrete circular rings are used for internal support. The earthwork is excavated to the foundation bottom plate 48, the water collection well 38 and the elevator shaft 39. The excavation depth is 21m. The present invention is proposed for construction.

[0074] See also Figure 1-5The columns 12 of the circular pier 2 are arranged at equal intervals of 6.4m along the circumferential direction of the circular pier 2. The reinforcement system of the channel steel connecting rods 13 between the columns 12 supported by the circular pier 2 adopts a non-continuous arrangement of one every other in the horizontal direction; in the vertical direction, a continuous cross arrangement is adopted. The oblique connecting rods (9m), transverse connecting rods (9×cos45°=6.4m) of the channel steel connecting rods 13 and the columns 12 form an isosceles right triangle, and the force is relatively balanced.

[0075] There are 7 plates with the same thickness as the plates of the circular trestle 2 evenly arranged around the circular trestle 2. While serving as a staggered vehicle and temporary earthwork yard, they can also be used as a template and processing area 3, a mechanical equipment storage area 4, a concrete pump truck station 5, a scaffolding support yard 6, a steel component yard 7, a steel bar and processing area 8, and a ramp 9; the middle of the circular trestle 2 is high and the two sides are low. The drainage holes 11 on the edge of the circular trestle 2 are symmetrically arranged with the central spine of the circular trestle 2, with a spacing of 6.4m, staggered with the position of the column 12, and the aperture of the drainage hole 11 is 40mm; the edge of the circular trestle 2 has a counter-slope 10 with a width of 300mm and a height of 500mm, and there is a protective railing 49 with a height of 1200mm on the counter-slope 10.

[0076] See also Figure 6 When the stress-bearing steel bars 18 of the support beam 16 of the inner support 1 cannot pass through the column 12, a connecting plate 17 is welded on the side of the column 12. The connecting plate 17 is C-shaped and is connected to the column 12 by welding the connecting plate 17 and the stress-bearing steel bars 18.

[0077] See also Figure 7-10, construct the first inner support 14, first cast the cushion layer 26 within the inner support range according to the design drawings, lay out the template control line, bracket and steel bar positioning line on the cushion layer 26, then place the steel bar pad at the bottom reinforcement, and tie the steel bars of the support beam 16. According to the design drawings, place the wooden pad at the designated position enclosed by the support beam 16, and set up the template frame (for the detailed setting process, refer to the utility model patent "A pier bridge slab template support structure for limited space for foundation pit support" authorization announcement number: CN219604160U), the template frame consists of a number of cross bars 21, vertical bars 22, spherical nodes 23, adjustable supports 24, adjustable bases 20, bolt threads 27, bottom molds 29, bottom mold wood 30, side molds 33, tension screws 31 and side mold wood 32, providing a working surface for steel bar tying. The steel bars of the circular trestle 2 are tied and formed into a whole with the steel bars of the support beam 16. At the position where the stress steel bars 18 of the support beam 16 cannot pass through the column 12, a connecting plate 17 is welded on the side of the column 12, and the stress steel bars 18 of the support beam 16 are connected to the connecting plate 17 by welding. In order to ensure the safety of the earthwork 25 excavation work under the circular trestle 2 in the next stage, when tying the bottom reinforcement of the circular trestle 2, a safety measure steel bar 28 is set, which passes through the lower spherical node 23 and is welded to the bottom reinforcement of the circular trestle 2 to prevent the template frame from falling as a whole and causing safety accidents to the construction machinery and personnel under the circular trestle 2.

[0078] See also Fig.11 The southeast corner of the foundation pit is gate 2#, and the southwest corner of the foundation pit is gate 1#. The earthwork excavation plane construction section is divided into four parts in the radial direction of the earthwork excavation plane, with the center point of the foundation pit as the center of the circle. The innermost part is a circle, the two middle parts are concentric rings, and the outermost part is formed by the edge of the foundation pit and the outer edge of the third ring. The chord direction takes the center point of the foundation pit as the center of the circle, and takes 45° (Note: different projects can customize the selected angle according to actual characteristics) as the basic unit array, dividing the entire foundation pit plane into 8×3+1=25 areas. The two mirror excavation areas form central symmetry with the center point of the foundation pit, which is convenient for symmetrical excavation. From outside to inside: A1, A1', A2, A2', A3, A3', A4, A4', B1, B1', B2, B2', B3, B3', B4, B4', C1, C1', C2, C2', C3, C3', C4, C4', D.

[0079] See also Fig.12, the earthwork excavation is divided into vertical construction sections. The first stage earthwork 34: earthwork excavation is symmetrical, layered and segmented from the top of the foundation pit (-0.700) to the crown beam 19 and the bottom of the first inner support 14 (-3.800); the second stage earthwork 35: pouring the first inner support 14, after the concrete strength of the first inner support 14 reaches the design strength requirement, excavation is carried out from the bottom of the first inner support 14 (-3.800) to the waist beam and the second inner support The bottom of support 15 (-11.450); the third stage earthwork 36: pour the second inner support 15, and after the concrete strength of the second inner support 15 reaches the design strength requirement, excavate from the bottom of the second inner support 15 (-11.450) to the bottom of the bottom plate 48 (-17.650); the fourth stage earthwork 37: excavate the elevator shaft 39, the pedestal 47 and the water collection well 38 (-21.000) at the bottom of the foundation pit. (Note: The vertical construction section division of earthwork excavation for different projects can be customized according to the depth characteristics of the foundation pit.)

[0080] See also Figure 13-15 , the first stage of excavation earthwork 34, from the top of the foundation pit (-0.700) to the bottom of the crown beam 19 and the first inner support 14 (-3.800), the earthwork excavation as a whole follows the excavation principles of zoning, segmentation, layering, symmetry, time limit, balanced excavation, and strictly prohibiting over-excavation. The first stage of earthwork 34 adopts the central island excavation, and the excavation order is to excavate the area far away from the gate first, then the area close to the gate, and then the backward excavation, and finally the horseway 43 ends. The muck truck 41 enters from the 2# door and exits from the 1# door. The excavation sequence is: A1A1'→A2A2'→A3A3'→A4→B1B1'→B2B2'→B3B3'→B4→C1C1'→C2C2'→C3C3'→C4→D→C4'→B4'→A4'. Then the tower crane 50 is installed, and the first inner support 14 is constructed according to the design drawings. The tower crane 50 can hoist the materials required for the inner support construction.

[0081] See also Figure 16-18After the concrete strength of the first inner support 14 reaches the design requirement, the second stage earthwork 35 is excavated, starting from the bottom of the first inner support 14 (-3.800) to the waist beam and the bottom of the second inner support 15 (-11.450). The excavation method is similar to that of the first stage. The overall excavation method is the center island type. The area far away from the gate is excavated first, and then the area near the gate is excavated, and finally the horseway 43 is finished. Earthmoving vehicles enter from Gate 2#, go down the circular trestle 2 through ramp 9, and then enter the foundation pit through horseway 43. The muck truck 41 filled with earth goes up the circular trestle 2 through horseway 43, and then goes up the road through ramp 9, and finally is transported out through Gate 1#. The earth excavation sequence is: A1A1'→A2A2'→A3A4→B1B1'→B2B2'→B3B4→C1C1'→C2C2'→C3C3'→C4→D→C4'→B3'B4'→A3'A4', and then the formwork support of the first inner support 14 is removed (for the detailed removal process, refer to the utility model patent "A trestle bridge slab formwork support structure for limited space of foundation pit support" authorization announcement number: CN219604160U), and then the second inner support 15 is constructed according to the design drawings.

[0082] See also Figure 19-21 After the concrete strength of the second inner support 15 reaches the design requirements, the third stage earthwork 36 is excavated, and the formwork support of the second inner support 15 is removed at the same time. The excavation is carried out from the bottom of the second inner support 15 (-11.450) to the bottom of the bottom plate 48 (-17.650). The earthwork excavation adopts the form of vertical excavation, and the composite excavation method combining the center island + basin is adopted as the whole. The earthwork at the bottom of the circular trestle 2 and the inner support 1 is first excavated by the excavator 40, and then transferred to the operating range of the grab shovel (long arm excavator) 42 by the scraper 44, and the grab shovel (long arm excavator) 42 on the circular trestle 2 is used to vertically take the earth. Then the earthwork in the central area is excavated by the excavator 40, and then transferred to the operating range of the grab shovel (long arm excavator) 42 by the scraper 44, and the grab shovel (long arm excavator) 42 on the circular trestle 2 is used to vertically take the earth, and finally the earthwork in the area near the circular trestle 2 is excavated. The muck truck 41 enters from Gate 2#, goes down the circular trestle 2 through the ramp 9, moves counterclockwise, and waits for loading at the grab shovel (long-arm excavator) 42. After the muck truck 41 is fully loaded with earth, it goes up the road through the ramp 9 and exits through Gate 1#. The order of earth excavation is: A1A1'→A2A2'→A3A3'→A4A4'→C1C1'→C2C2'→C3C3'→C4C4'→B1B1'→B2B2'→B3B3'→B4B4'.

[0083] See also Fig.25The traffic guidance diagram shows that construction vehicles must strictly follow the weight and speed specified by the load limit signs 51 and speed limit signs 52 on the trestle board, and must keep the center line sign 53 of the circular trestle 2. It is strictly forbidden to drive over the side line sign 54 of the circular trestle 2. Construction vehicles such as empty muck trucks 41 or concrete mixer trucks 45 enter the construction site from Gate 2#, go downhill to the circular trestle 2, and move counterclockwise. When encountering mechanical sites 55 such as grab shovels (long-arm excavators) 42 and concrete pump trucks 46, formwork and processing areas 3, mechanical equipment storage areas 4, concrete pump truck sites 5, scaffolding support yards 6, steel component yards 7, and steel bars and processing areas 8, they can pass each other at the passing platform according to the traffic guidance diagram. Muck trucks 41 loaded with soil or concrete mixer trucks 45 that have completed transportation leave the construction site from Gate 1#, and the traffic is efficient and fast.

[0084] See also Figure 22-24 , excavate the fourth stage earthwork 37, excavate the earthwork of pits within pits such as the elevator shaft 39, the pedestal 47 and the water collection well 38 (-21.000), and provide a working surface for the construction of the bottom plate 48. Similarly, earth is taken vertically by the grab shovel (long arm excavator) 42 on the circular trestle 2. The earth at the bottom of the circular trestle 2 and the inner support 1 is excavated first, and then the earth in the central area is excavated, and finally the earth in the area near the circular trestle 2 is excavated. After the earth excavation in the corresponding area is completed, the bottom plate 48 is poured in time. The traffic organization of earthwork vehicles is the same as that in the third stage. The concrete mixer truck 45 and the concrete pump truck 46 enter from the 2# door, go down the circular trestle 2 through the ramp 9, move counterclockwise, stop at the passing platform, and carry out concrete pouring operations. After the concrete mixer truck 45 pours the concrete, it goes up the road through the ramp 9 and is finally transported out through the 1# door. The specific earthwork excavation sequence is: A1A1'→A2A2'→A3A3'→A4A4'→C1C1'→C2C2'→C3C3'→C4C4'→B1B1'→B2B2'→B3B3'→B4B4'.

[0085] The above description is only a specific implementation of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be understood by anyone familiar with the technology within the technical scope disclosed by the present invention should be included in the scope of the present invention.

Claims

1. A trestle structure for construction in a complex environment of a hexagonal deep foundation pit, characterized in that: It comprises an annular trestle (2), columns (12) arranged at equal intervals along the annular direction of the annular trestle (2) and supporting the annular trestle (2), a channel steel connecting rod (13) connected between the columns (12), and a supporting beam (16) connected to a node at the top of the columns (12); The template frame of the annular trestle (2) is composed of a crossbar (21), a vertical bar (22), a spherical node (23), an adjustable support (24), an adjustable base (20), a bottom mold (29), a bottom mold wood (30), a side mold (33), a tension screw (31) and a side mold wood (32); A connecting plate (17) is provided on the side of the column (12), and the stress-bearing steel bars (18) of the support beam (16) are connected to the connecting plate (17) by welding.

2. The trestle structure for complex environment construction of hexagonal deep foundation pit according to claim 1 is characterized in that: The crossbar (21), the vertical bar (22), the spherical node (23), the adjustable support (24) and the adjustable base (20) are provided with bolt threads (27) and connected to form an integral formwork support frame through the bolt threads (27). The steel bars (28) for safety measures to prevent the formwork frame from falling as a whole are welded to the bottom bars of the ring-shaped trestle (2) after holding the lower spherical node (23).

3. The trestle structure for construction in a complex environment of a hexagonal deep foundation pit according to claim 1 is characterized in that: The upright posts (12) and the channel steel connecting rods (13) are continuously arranged in a cross-arranged manner, and the oblique connecting rods, the transverse connecting rods and the upright posts (12) of the channel steel connecting rods (13) form an isosceles right triangle.

4. The trestle structure for complex environment construction of hexagonal deep foundation pit according to claim 1 is characterized in that: The annular trestle (2) is high in the middle and low on both sides, and has drainage holes (11) on the edge. The edge of the annular trestle (2) has a reverse ridge (10), and a protective railing (49) is arranged on the reverse ridge (10).

5. The trestle structure for construction in a complex environment of a hexagonal deep foundation pit according to claim 4 is characterized in that: The columns (12) of the annular trestle (2) are arranged at intervals of 6m to 9m; the drainage holes (11) at the edge of the annular trestle (2) are symmetrically arranged with respect to the central spine of the annular trestle (2) at intervals of 6m to 9m, staggered from the positions of the columns (12), and the diameter of the drainage holes (11) is 30mm to 50mm.

6. The trestle structure for construction in a complex environment of a hexagonal deep foundation pit according to claim 1 is characterized in that: The annular trestle (2) is evenly arranged with 7 plates of the same thickness as the annular trestle (2). In addition to being used as a staggered vehicle and temporary earthwork storage yard, it can also be used as a template and processing area (3), a mechanical equipment storage area (4), a concrete pump truck station (5), a scaffolding support yard (6), a steel component yard (7), a steel bar and processing area (8), and a ramp (9).

7. An earthwork construction method for a complex environment of a hexagonal deep foundation pit based on the trestle structure according to any one of claims 1 to 6, characterized in that: The steps are: S1. Earthwork excavation plane and vertical construction section division; Earthwork excavation plane construction section division The radial direction of the earthwork excavation plane is divided into four parts with the center point of the foundation pit as the center of the circle. The innermost part is a circle, the two middle parts are concentric rings, and the outermost part is formed by the foundation pit edge line and the outer edge line of the third ring; The chord direction takes the center point of the foundation pit as the center of the circle and 45° as the basic unit array to divide the entire foundation pit plane into 8×3+1=25 areas. The two mirror excavation areas form central symmetry with the center point of the foundation pit to facilitate symmetrical excavation. From outside to inside, they are: A1, A1', A2, A2', A3, A3', A4, A4', B1, B1', B2, B2', B3, B3', B4, B4', C1, C1', C2, C2', C3, C3', C4, C4', D; S2, excavate the first stage earthwork (34), excavate to the bottom of the crown beam (19) of the first inner support (14), and construct the first inner support (14); excavate the earthwork symmetrically, layered, and segmented from the top of the foundation pit to the crown beam (19) and the bottom of the first inner support (14); excavate the first stage earthwork (34), excavate from the top of the foundation pit to the crown beam (19) and the bottom of the first inner support (14), and the earthwork excavation is carried out in accordance with the principles of zoning, segmentation, layering, symmetry, time limit, balanced excavation, and strict prohibition of over-excavation; the first stage earthwork (34) adopts the central island excavation, and the excavation order is based on the excavation away from the large The gate area is excavated first, and the area near the gate is excavated later, and the excavation is carried out in a backward manner, and finally the horseway (43) is finished; the muck truck (41) enters from the 2# gate at the southeast corner of the foundation pit and exits from the 1# gate at the southwest corner of the foundation pit. The earth excavation sequence is: A1A1'→A2A2'→A3A3'→A4→B1B1'→B2B2'→B3B3'→B4→C1C1'→C2C2'→C3C3'→C4→D→C4'→B4'→A4', and then the tower crane 50 is installed, and at the same time, the first inner support (14) is constructed according to the design drawings, and the tower crane (50) hoists the materials required for the inner support construction; S3, when the concrete strength of the first inner support (14) reaches the design strength, excavate the second stage earthwork (35) to the bottom of the waist beam of the second inner support (15), and construct the second inner support (15); excavate from the bottom of the first inner support (14) to the waist beam and the bottom of the second inner support (15), the excavation method is similar to the first stage, the overall excavation method is the center island type, first excavate the area far from the gate, then excavate the area near the gate, and finally end with the horseway (43); earthwork vehicles enter from Gate 2#, go down the circular trestle (2) through the ramp (9), and then go through The horseway (43) enters the foundation pit, and the muck truck (41) loaded with earth passes through the horseway (43) onto the circular trestle (2), then onto the road via the ramp (9), and finally is transported out through the 1# gate. The earth excavation sequence is: A1A1'→A2A2'→A3A4→B1B1'→B2B2'→B3B4→C1C1'→C2C2'→C3C3'→C4→D→C4'→B3'B4'→A3'A4', then the formwork support of the first inner support (14) is removed, and then the second inner support (15) is constructed according to the design drawings; S4, when the concrete strength of the second inner support (15) reaches the design strength, the third stage earthwork (36) is excavated to the foundation bottom plate (48) and the bottom of the cushion layer; the third stage earthwork (36) is excavated, and the formwork support of the second inner support (15) is removed at the same time, and the excavation is carried out from the bottom of the second inner support (15) to the bottom of the bottom plate (48). The earthwork excavation adopts a vertical excavation form, and the overall composite excavation method combining the center island + basin type is adopted. The earthwork at the bottom of the circular trestle (2) and the inner support (1) is first excavated by an excavator (40), and then transferred to the operating range of the grab shovel (42) by a scraper (44), and the earth is vertically taken by the grab shovel (42) on the circular trestle (2); and the earthwork in the central area is then excavated by an excavator. The machine (40) excavates the soil, and then the soil is transferred to the operating range of the grab shovel (42) by the scraper (44), and the grab shovel (42) on the circular trestle (2) is used to vertically take soil, and finally the soil in the area near the circular trestle (2) is excavated; the muck truck (41) enters from the 2# door, goes down the circular trestle (2) through the ramp (9), moves counterclockwise, and waits for soil to be loaded at the grab shovel (42). After the muck truck (41) is fully loaded with soil, it goes up the road through the ramp (9) and exits through the 1# door. The order of soil excavation is: A1A1'→A2A2'→A3A3'→A4A4'→C1C1'→C2C2'→C3C3'→C4C4'→B1B1'→B2B2'→B3B3'→B4B4'; S5, excavate the fourth stage earthwork (37), excavate the elevator shaft (39), the pedestal (47) and the water collection well (38), cast the cushion layer and the bottom plate (48) in time, use the grab shovel (42) on the circular trestle (2) to vertically take earthwork, first excavate the earthwork at the bottom of the circular trestle (2) and the inner support (1), then excavate the earthwork in the central area, and finally excavate the earthwork in the area near the circular trestle (2). After the earthwork excavation in the corresponding area is completed, cast the bottom plate (48) in time, and organize the earthwork vehicle traffic as in the third stage, concrete mixer trucks (45) and The concrete pump truck (46) enters from Gate 2#, passes through the ramp (9) to the circular trestle (2), moves counterclockwise, stops at the platform for placing concrete, and after the concrete mixer truck (45) has finished placing concrete, it passes through the ramp (9) to the road, and finally is transported out through Gate 1#. The specific earthwork excavation sequence is: A1A1'→A2A2'→A3A3'→A4A4'→C1C1'→C2C2'→C3C3'→C4C4'→B1B1'→B2B2'→B3B3'→B4B4'.

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