Foundation pit concrete inner support post-dismantling structure construction method

Abstract

The invention relates to a construction method of a foundation pit concrete inner support post-dismantling structure. The construction method comprises the following steps that firstly, construction preparation is conducted; secondly, an inner supporting cushion layer is poured; thirdly, inner supporting beam steel bars and water stop steel plates are installed; fourthly, basement outer wall vertical steel bars and basement outer wall horizontal steel bars are pre-buried; fifthly, an inner supporting beam formwork is installed; sixthly, inner supporting beam concrete is poured; seventhly, construction is conducted below an inner support; eighthly, basement outer wall horizontal steel bars and basement outer wall vertical steel bars are connected; ninthly, a basement outer wall structure is constructed; and tenthly, the inner support is dismantled. According to the post-dismantling construction method for the inner support of the deep foundation pit, construction is convenient, the connection stress problem of the horizontal steel bars and the vertical steel bars of the outer wall of the basement can be solved, and the waterproof and anti-seepage problems of the post-dismantling inner support can also be solved.

Description

Technical Field

[0001] The invention belongs to the technical field of building construction, and particularly relates to a foundation pit concrete inner support post-dismantling structure construction method. Background Art

[0002] With the construction of cities and the development of underground space, deep foundation pit basements have been used more and more. The reinforced concrete inner supports of deep foundation pits need to be replaced and removed layer by layer as the basement is constructed. In order to avoid the influence of the replacement and removal process on the construction of the superstructure, the post-removal method of the inner support is adopted.

[0003] The journal article "Application of Post-dismantling Construction Technology of Foundation Pit Support Beams" published in the 10th issue of Volume 41 of "Building Technology Development" in October 2014 disclosed a construction method of post-dismantling internal supports. A hole is left in the outer wall of the basement, and the hole is sealed after the internal supports are removed. However, in this construction method, the removal and hoisting are likely to conflict with the water-stop steel plate, making the removal and hoisting difficult. At the same time, the vertical and horizontal steel bars of the cut basement outer wall in the same section are all connected by welding. For walls with seismic fortification and backfill load requirements, the steel bar connection stress is affected. It is difficult to reinforce the formwork at the hole position in the wall and chisel the construction joint before sealing. There are also problems with waterproofing and anti-leakage. Summary of the invention

[0004] The purpose of the present invention is to provide a method for post-dismantling construction of deep foundation pit internal supports which is convenient for construction, which can not only solve the stress problem of horizontal steel bars and vertical steel bars connecting the basement outer wall, but also solve the problem of waterproofing and anti-leakage of post-dismantling internal supports.

[0005] The technical solution of the present invention is a method for constructing a foundation pit concrete internal support post-dismantling structure, comprising the following steps:

[0006] Step 1: Construction preparation;

[0007] Cut and manufacture a water-stop steel plate according to the cross-sectional dimensions of the reserved support beam, and open a through hole on the water-stop steel plate for the main reinforcement of the reserved support beam to pass through;

[0008] Step 2: pouring the inner support cushion layer;

[0009] After positioning and laying out the basement exterior wall and the waterproof steel plate, pour the inner support cushion layer, and leave an installation seam for the waterproof steel plate on the cushion layer;

[0010] Step 3: Install the inner support beam reinforcement and water stop steel plate;

[0011] First, the main reinforcement of the reserved support beam and the water-stop steel plate are installed and embedded in the reserved support beam at the same time, and at least part of the water-stop steel plate extends out of the reserved support beam and surrounds the outside of the reserved support beam; then, the main reinforcement of the inner support beam is extended by the main reinforcement sleeves connected at both ends of the main reinforcement of the reserved support beam, and the stirrups of the inner support beam are installed;

[0012] Step 4: Pre-embed the horizontal reinforcement of the basement exterior wall and the vertical reinforcement of the basement exterior wall;

[0013] Install the embedded horizontal reinforcement of the basement exterior wall and the embedded vertical reinforcement of the basement exterior wall in the reserved support beam. The embedded horizontal reinforcement of the basement exterior wall is connected with a horizontal reinforcement sleeve, and both ends of the embedded vertical reinforcement of the basement exterior wall are connected with a vertical reinforcement sleeve;

[0014] Step 5: Install the inner support beam formwork;

[0015] The inner support beam is reinforced by installing formwork, and is installed in sections on both sides of the waterstop steel plate according to the position of the waterstop steel plate to clamp the waterstop steel plate;

[0016] Step 6: pouring concrete for inner support beam;

[0017] Install wire mesh on both sides of the basement outer wall edge line to form a basement outer wall concrete pouring section outside the basement outer wall edge line; first pour the basement outer wall concrete pouring section with concrete consistent with the basement outer wall, and then pour the inner support beam section outside the basement outer wall concrete pouring section with inner support beam concrete;

[0018] Step 7: Construction of internal support;

[0019] After the inner support beam is removed from the formwork, square timber back ribs are installed on both sides of the waterstop steel plate and reinforced to protect the waterstop steel plate;

[0020] Step 8: Connect the horizontal reinforcement of the basement exterior wall and the vertical reinforcement of the basement exterior wall;

[0021] The horizontal reinforcement of the basement exterior wall is extended through the horizontal reinforcement sleeve, and the vertical reinforcement of the basement exterior wall is extended through the vertical reinforcement sleeve;

[0022] Step 9: Construction of basement exterior wall structure;

[0023] After the horizontal reinforcement of the basement exterior wall and the vertical reinforcement of the basement exterior wall are extended, the template is installed and reinforced on the basement exterior wall, and then the basement exterior wall is poured. The template is tightly pressed against the inner support beam to prevent leakage;

[0024] Step 10: Remove the inner support beams.

[0025] Preferably, the waterstop steel plate is a rectangular waterstop ring with an opening in the middle, the rectangular waterstop ring is made of a steel plate with a thickness of 3-5 mm and is galvanized before embedding; the waterstop steel plate includes a first part embedded in the reserved support beam and a second part surrounding the outside of the reserved support beam, the width of the four sides of the first part is 100-150 mm, and the width of the four sides of the second part is 100-150 mm; the through holes are arranged at intervals on the first part and the hole diameter thereof is 4-5 mm larger than the diameter of the main reinforcement of the reserved support beam;

[0026] When the inner support beam and the crown beam are obliquely intersected, the opposite ends of the second part located on both sides of the reserved support beam are bent along the edge line of the reserved support beam to be perpendicular to the construction joint.

[0027] Preferably, step one further comprises:

[0028] The threads of the main reinforcement of the inner support beam are made for threaded connection with the main reinforcement sleeve. The two ends of the main reinforcement of the inner support beam are straight threaded and galvanized. The threads of the horizontal reinforcement of the basement exterior wall are made for threaded connection with the horizontal reinforcement sleeve. The threads of the vertical reinforcement of the basement exterior wall are made for threaded connection with the vertical reinforcement sleeve.

[0029] Preferably, before pouring the cushion layer of the inner support beam in step 2, the cushion layer under the reserved support beam is excavated and thickened, and the thickness of the cushion layer under the reserved support beam is greater than or equal to the width of the second part of the waterstop steel plate; after pouring the cushion layer, the basement outer wall edge line and the waterstop steel plate are accurately positioned and laid out on the cushion layer for subsequent pre-embedding.

[0030] Preferably, in step three, the main reinforcement of the reserved support beam passes through the through hole of the water-stop steel plate and is then circumferentially welded to seal the gap between the main reinforcement of the reserved support beam and the through hole; the length of the main reinforcement of the reserved support beam is about 10 mm shorter than the thickness of the basement outer wall.

[0031] Preferably, the total length of the embedded horizontal steel bars of the basement exterior wall and the two end horizontal steel bar sleeves in step four is equal to the horizontal length of the reserved support beam section; the total length of the embedded vertical steel bars of the basement exterior wall and the two end vertical steel bar sleeves is equal to the vertical length of the reserved support beam section; the horizontal steel bar sleeves and the vertical steel bar sleeves are both filled with foaming agent.

[0032] As a preference, the specific operation of step five is:

[0033] Formwork, wooden secondary back ribs and steel pipe main back ribs are installed in sequence on both sides of the inner support beam. The wooden secondary back ribs are arranged at intervals on the outside of the formwork and extend along the length direction of the formwork. Two steel pipe main back ribs form a group, and multiple groups of steel pipe main back ribs are arranged at intervals on the outside of the wooden secondary back ribs and extend along the width direction of the formwork. After the tension screws pass through the formwork, the steel pipe main back ribs and wooden secondary back ribs are fixed by mountain clips and nuts. The formwork and wooden secondary back ribs on both sides of the waterstop steel plate clamp the waterstop steel plate.

[0034] Preferably, the tension screw adopts a three-section structure, including an inner tension screw rod and an outer tension screw rod connected to both ends of the inner tension screw rod, the outer tension screw rod is connected to the inner tension screw rod through a steel sleeve; the embedded horizontal steel bars of the basement exterior wall located at the reserved support beam position serve as the inner tension screw rod, and the outer tension screw rod is connected through a horizontal steel sleeve; after the formwork is installed and reinforced, the end of the horizontal steel sleeve is in close contact with the formwork; after the concrete of the inner support beam is poured, the outer tension screw rod is removed, and the embedded horizontal steel bars of the basement exterior wall and the horizontal steel sleeve are retained for connecting the horizontal steel bars of the basement exterior wall; when the diameters of the outer tension screw rod and the embedded horizontal steel bars of the basement exterior wall are different, the horizontal steel sleeve adopts a reducing sleeve to ensure the connection.

[0035] Preferably, after the inner support beam is demolded in step seven, the outer rod of the tension screw penetrates the secondary back rib of the square timber and is connected to the pre-embedded horizontal steel bars of the basement outer wall through a horizontal steel bar sleeve to form a tension screw, and the tension screw fixes the secondary back rib of the square timber through a mountain-shaped clip and a nut; the thickness of the secondary back rib of the square timber is greater than or equal to the width of the second part of the waterstop steel plate.

[0036] Preferably, the specific operation of step eight is: after the basement exterior wall below the inner support is completed to the inner support elevation, the contact surface between the inner support beam and the basement exterior wall is roughened with concrete, and after the foaming agent foam in the horizontal steel bar sleeve and the vertical steel bar sleeve is cleaned, the horizontal steel bars of the basement exterior wall and the vertical steel bars of the basement exterior wall are connected. After the steel bars are extended, the structural steel bars of the basement exterior wall and the reserved support beam structural steel bars are pulled through to form a complete through-length steel bar; the specific operation of step ten is: after the construction of the basement structure above the inner support is completed, the inner support beam is dismantled, and the main reinforcement sleeve is removed after the inner support beam is cut and dismantled, and the position left in the main reinforcement sleeve is filled with a waterproof mortar protective layer to prevent the steel bars from rusting from the outside to the inside.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] ⑴ By pre-embedding the horizontal steel bars and horizontal steel bar sleeves, the vertical steel bars and vertical steel bar sleeves of the basement exterior wall in the reserved support beams, it is convenient to connect the horizontal steel bars and the vertical steel bars of the basement exterior wall during the construction process, and effectively solve the connection force problem of the horizontal steel bars and the vertical steel bars of the basement exterior wall. In the later construction, the reserved support beams are used as part of the basement exterior wall, and there is no need to dismantle them, which is convenient for construction.

[0039] ⑵ Both ends of the main reinforcement of the reserved support beam, the embedded horizontal reinforcement of the basement and the embedded vertical reinforcement of the basement are connected to the sleeve by threaded method, so that the main reinforcement sleeve, horizontal reinforcement sleeve and vertical reinforcement sleeve are easy to disassemble and assemble; because the main reinforcement sleeve is located at the edge of the basement outer wall, it is conducive to the later demolition and exterior wall repair and waterproofing construction, and the embedded horizontal reinforcement of the basement and the embedded vertical reinforcement of the basement are completely buried in the reserved support beam, which can avoid scratches on the hoisted objects, thereby improving construction safety and protection of finished products.

[0040] ⑶ By burying a waterstop steel plate in the reserved support beam, at least part of the waterstop steel plate extends out of the reserved support beam and surrounds the outside of the reserved support beam. After the main reinforcement of the reserved support beam is perforated, the gap between the main reinforcement of the reserved support beam and the waterstop steel plate is welded and sealed to effectively solve the problem of waterproofing and anti-leakage of the internal support after removal.

[0041] (4) The waterstop steel plate is made into a rectangular waterstop ring with an opening in the middle. The opening in the middle of the waterstop ring can ensure the integrity and continuity of the inner support beam structure, so that the concrete structure of the inner support beam will not be isolated or cut off by the waterstop steel plate; after the waterstop steel plate is opened with a hole, the continuity of the main reinforcement of the inner support beam can be ensured, so that the main reinforcement of the inner support beam will not be cut off by the waterstop steel plate.

[0042] ⑸ During the formwork reinforcement construction, the formwork of the inner support beam and the basement outer wall is reinforced by using three-section tension screws to facilitate the later formwork removal construction; at the same time, by using the pre-buried horizontal steel bars and horizontal steel bar sleeves of the basement outer wall to connect with the outer rod of the tension screw to form a three-section tension screw. After the concrete of the inner support beam is poured, the outer rod of the tension screw is removed, and the pre-buried horizontal steel bars and horizontal steel bar sleeves of the basement outer wall are retained for connecting the horizontal steel bars of the basement outer wall. This not only saves tension screw materials and reduces construction costs, but also shortens construction time and improves construction efficiency.

[0043] ⑹ During the formwork reinforcement construction, the formwork reinforcement structure is installed and reinforced in sections on both sides of the waterstop steel plate according to the position of the waterstop steel plate. The formwork and the secondary back ribs clamp the waterstop steel plate, which can effectively prevent leakage during the pouring process; after the inner support beam is demolded, three-section tension screws are used on both sides of the waterstop steel plate to fix the square wood secondary back ribs, which can effectively protect the waterstop steel plate and prevent it from being damaged by the pile driver during earth excavation and other operations. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is a construction flow chart of the post-removal of support in a deep foundation pit of the present invention;

[0045] Figure 2 It is a schematic cross-sectional diagram of foundation pit support of the present invention;

[0046] Figure 3 It is a partial plane diagram of the inner support beam in the orthogonal working condition between the crown beam and the inner support;

[0047] Figure 4 yes Figure 3 Schematic diagram of partial section of basement exterior wall;

[0048] Figure 5 yes Figure 3 A schematic cross-sectional view of the reserved support beam;

[0049] Figure 6 yes Figure 5 A schematic plan view of the main reinforcement of the reserved support beam of the reserved support beam;

[0050] Figure 7 yes Figure 5 Schematic diagram of the water stop steel plate;

[0051] Figure 8 yes Figure 5 Schematic diagram of the elevation of the water-stop steel plate;

[0052] Fig. 9 It is a schematic plan view of the reinforcement of the inner support beam template of the present invention;

[0053] Fig.10 It is a schematic cross-sectional view of the reinforcement of the inner support beam template of the present invention;

[0054] Fig.11 yes Fig.10 Schematic diagram of the connection between the inner support beam and the formwork;

[0055] Fig.12 yes Fig.10 A partial enlarged view of the middle part;

[0056] Fig.13 This is a schematic plan view of the inner support beam after demoulding of the present invention;

[0057] Fig.14 yes Figure 3 Schematic diagram of the cross-section of the horizontal and vertical reinforcements of the embedded shear wall;

[0058] Fig.15 yes Fig.14 Schematic diagram of the extension of horizontal and vertical steel bars;

[0059] Fig.16 It is a schematic plan view of the basement exterior wall formwork reinforcement of the present invention;

[0060] Fig.17 It is a cross-sectional schematic diagram of the basement exterior wall formwork reinforcement of the present invention;

[0061] Fig.18 It is a schematic diagram of the basement exterior wall formwork reinforcement elevation of the present invention;

[0062] Fig.19 It is a partial plane diagram of the inner support beam in the oblique intersection condition between the crown beam and the inner support;

[0063] Fig. 20 yes Fig.19 Schematic diagram of the water stop steel plate;

[0064] Fig.21 yes Fig.19 Schematic diagram of the water-stop steel plate elevation.

[0065] Main component symbols:

[0066] Reserved support beam 1; water stop steel plate 11; through hole 111; first part 112; second part 113; reserved support beam main reinforcement 12; main reinforcement sleeve 121; reserved support beam edge 13; construction joint 14; embedded basement exterior wall horizontal reinforcement 15; horizontal reinforcement sleeve 151; embedded basement exterior wall vertical reinforcement 16; vertical reinforcement sleeve 161; inner support beam 2; inner support beam main reinforcement 21; inner support beam stirrup 22; basement exterior wall 3 ; Basement exterior wall edge line 31; Basement exterior wall horizontal steel bars 32; Basement exterior wall vertical steel bars 33; Basement exterior wall concrete pouring section 34; Crown beam 4; Pad 5; Installation joint 51; Formwork reinforcement structure 6; Formwork 61; Wood secondary back rib 62; Steel pipe main back rib 63; Tension screw 64; Tension screw outer rod 641; Tension screw inner rod 642; Steel bar sleeve 643; Mountain-shaped card 65; Nut 66; Square wood secondary back rib 67; Wire mesh 7. DETAILED DESCRIPTION

[0067] The present invention will be further described below in conjunction with the accompanying drawings:

[0068] See also Figure 1 to Figure 2 As shown, the present invention provides a method for constructing a foundation pit concrete internal support post-dismantling structure, comprising the following steps:

[0069] Step 1: Construction preparation;

[0070] The water-stop steel plate 11 is cut and manufactured according to the cross-sectional size of the reserved support beam 1, and a through hole 111 is opened on the water-stop steel plate 11 for the main reinforcement 12 of the reserved support beam to pass through; wherein the reserved support beam 1 is located at the overlapping position of the inner support beam 2 and the outer wall 3 of the basement.

[0071] In this embodiment, if Figure 8As shown, the waterstop steel plate 11 is a rectangular waterstop ring with an opening in the middle. The rectangular waterstop ring is made of a steel plate with a thickness of 3-5mm and is galvanized before embedding. The waterstop steel plate 11 is cut and made according to the cross-section of the reserved support beam 1 and the arrangement of the reserved support beam main reinforcement 12. A hole is opened at the position of the reserved support beam main reinforcement 12. The number and position of the through holes 111 correspond to the number and position of the reserved support beam main reinforcement 12. By setting the waterstop steel plate as a rectangular waterstop ring with an opening in the middle, the integrity and continuity of the inner support beam structure can be guaranteed after the middle opening of the waterstop ring, so that the concrete structure of the inner support beam will not be isolated or cut off by the waterstop steel plate; after the hole is opened on the waterstop steel plate, the continuity of the inner support beam main reinforcement can be guaranteed, so that the inner support beam main reinforcement will not be cut off by the waterstop steel plate.

[0072] The water stop steel plate 11 includes a first part 112 embedded in the reserved support beam 1 and a second part 113 surrounding the outside of the reserved support beam 1. The width d1 of the four sides of the first part 112 is 100-150mm, that is, the width d1 of the four sides of the rectangular water stop ring embedded in the reserved support beam 1 is 100-150mm; the width d2 of the four sides of the second part 113 is 100-150mm; that is, the width d2 of the four sides of the rectangular water stop ring exposed outside the reserved support beam 1 is 100-150mm. Through holes 111 are arranged at intervals on the first part 112, and the aperture of the through holes 111 is 4-5mm larger than the diameter of the main reinforcement 12 of the reserved support beam, so that the main reinforcement of the reserved support beam can pass through the through holes smoothly.

[0073] It is worth noting that when the inner support beam 2 is orthogonal to the crown beam 4, Figure 3 , Figure 7 As shown, the water stop steel plate 11 is located in the middle of the thickness direction of the basement outer wall 3, and the water stop steel plate 11 and the basement outer wall 3 are located in the same vertical plane; when the inner support beam 2 and the crown beam 4 are obliquely intersected, as shown in FIG. Figures 19 to 21 As shown, the water stop steel plate 11 is located in the middle of the thickness direction of the basement outer wall 3, and the second part 113 of the water stop steel plate 11 is located at the opposite ends of the reserved support beam 1, and is bent along the reserved support beam edge 13 to be perpendicular to the construction joint 14, and is reinforced to ensure the waterproof and anti-seepage performance of the basement outer wall. In this embodiment, Fig.21 As shown, the reserved support beam edge line 13 is the folding line of the water-stopping steel plate 11 , and the water-stopping steel plates located on both sides of the reserved support beam 1 are bent along the folding line to be perpendicular to the construction joint 14 .

[0074] In this embodiment, the construction preparation also includes: making threads for the main reinforcement of the inner support beam for threaded connection with the main reinforcement sleeve, and installing part of the main reinforcement of the inner support beam as the reserved support beam main reinforcement in the reserved support beam, and straight threads at both ends of the reserved support beam main reinforcement are galvanized; making threads for the horizontal steel bars of the basement exterior wall for threaded connection with the horizontal steel bar sleeve, and installing part of the horizontal steel bars of the basement exterior wall as the pre-embedded horizontal steel bars of the basement exterior wall in the reserved support beam, and pre-making threads at both ends of the pre-embedded horizontal steel bars of the basement exterior wall and connecting them with the horizontal steel bar sleeve; making threads for the vertical steel bars of the basement exterior wall for threaded connection with the vertical steel bar sleeve, and installing part of the vertical steel bars of the basement exterior wall as the pre-embedded vertical steel bars of the basement exterior wall in the reserved support beam, and pre-making threads at both ends of the pre-embedded vertical steel bars of the basement exterior wall and connecting them with the vertical steel bar sleeve.

[0075] Step 2: pouring the inner support cushion layer;

[0076] Before pouring the cushion layer of the inner support beam, the basement outer wall 3 and the water stop steel plate 11 are positioned and laid out. Figure 4 As shown, the cushion layer below the reserved support beam 1 is excavated and thickened, and a film is laid; the thickness of the cushion layer below the reserved support beam 1 is greater than or equal to the width d2 of the second portion 113 of the water-stop steel plate 11; in this embodiment, as Figure 4 As shown, the thickness of the cushion layer under the reserved support beam 1 is equal to the width d2 of the second part 113 of the waterstop steel plate 11, and the width d2 of the second part 113 is 100-150mm. When the cushion layer of the inner support beam is cast, an installation seam 51 of the waterstop steel plate 11 is reserved on the cushion layer 5 under the reserved support beam 1, and the depth of the installation seam 51 is equal to the width d2 of the second part 113 of the waterstop steel plate 11, so as to ensure that in the subsequent installation process of the waterstop steel plate 11, the exposed part of the waterstop steel plate 11 can be fully inserted into the gap of the cushion layer, so as to facilitate the installation of the waterstop steel plate. After casting the cushion layer, the basement outer wall edge line 31 and the waterstop steel plate 11 are accurately positioned and laid out on the cushion layer 5 for subsequent pre-embedding.

[0077] Step 3: Install the inner support beam reinforcement and water stop steel plate;

[0078] like Figure 3 , Figure 7 As shown, the reserved support beam main reinforcement 12 and the water-stop steel plate 11 are first installed simultaneously and embedded in the reserved support beam 1. The reserved support beam main reinforcement 12 passes through the through hole 111 of the water-stop steel plate 11 and is then circumferentially welded to seal the gap between the reserved support beam main reinforcement 12 and the through hole 111.

[0079] At least part of the water stop steel plate 11 extends out of the reserved support beam 1 and surrounds the outside of the reserved support beam 1; in this embodiment, Figure 5As shown, the first portion 112 of the waterstop steel plate 11 is embedded in the reserved support beam 1 , and the second portion 113 of the waterstop steel plate 11 surrounds the outer side of the reserved support beam 1 .

[0080] like Figures 3 to 5 As shown, after the reserved support beam main reinforcement 12 and the water stop steel plate 11 are installed, the inner support beam main reinforcement 21 is extended by the main reinforcement sleeves 121 connected at both ends of the reserved support beam main reinforcement 12, and the inner support beam stirrups 22 are installed;

[0081] like Figure 6 As shown, the length of the reserved support beam main reinforcement 12 is about 10 mm shorter than the thickness of the basement outer wall 3, and the main reinforcement sleeve 121 is located at the basement outer wall edge 31, which is convenient for connection with the inner support beam main reinforcement, and also convenient for later removal and wall repair.

[0082] Step 4: Pre-embed the horizontal reinforcement of the basement exterior wall and the vertical reinforcement of the basement exterior wall;

[0083] See also Fig.14 As shown, embedded basement exterior wall horizontal steel bars 15 and embedded basement exterior wall vertical steel bars 16 are installed in the reserved support beam 1, the embedded basement exterior wall horizontal steel bars 15 are connected with horizontal steel bar sleeves 151, and the total length of the embedded basement exterior wall horizontal steel bars 15 and the two end horizontal steel bar sleeves 151 is equal to the horizontal length of the cross section of the reserved support beam 1; the two ends of the embedded basement exterior wall vertical steel bars 16 are connected with vertical steel bar sleeves 161, and the total length of the embedded basement exterior wall vertical steel bars 16 and the two end vertical steel bar sleeves 161 is equal to the vertical length of the cross section of the reserved support beam 1.

[0084] In this embodiment, both the horizontal steel bar sleeve 151 and the vertical steel bar sleeve 161 are ordinary first-class sleeves, so that the strength of the sleeve is higher than the strength of the horizontal steel bars and the vertical steel bars of the basement outer wall, so as to ensure that the connection of the horizontal steel bars and the vertical steel bars of the basement outer wall in the same section meets the strength requirements. Both the horizontal steel bar sleeve 151 and the vertical steel bar sleeve 161 are filled with foaming agent to prevent concrete slurry from flowing into the sleeve during the pouring of the inner support beam concrete.

[0085] Step 5: Install the inner support beam formwork;

[0086] The inner support beam 1 is reinforced by template installation to form Fig. 9 The template reinforcement structure 6 shown in the figure is installed in sections on both sides of the water stop steel plate 11 according to the position of the water stop steel plate 11 to clamp the water stop steel plate 11; for details, please read Figures 9 to 11As shown, the template 61, the secondary wood back ribs 62 and the main steel pipe back ribs 63 are installed on both sides of the inner support beam 1 in sequence. The secondary wood back ribs 62 are arranged at intervals on the outside of the template 61 and extend along the length direction of the template 61. The main steel pipe back ribs 63 are grouped in pairs. Multiple groups of main steel pipe back ribs 63 are arranged at intervals on the outside of the secondary wood back ribs 62 and extend along the width direction of the template 61. The tension screws 64 penetrate the template 61 and then fix the main steel pipe back ribs 63 and the secondary wood back ribs 62 through the mountain clamps 65 and nuts 66. The templates 61 and the secondary wood back ribs 62 on both sides of the waterstop steel plate 11 clamp the waterstop steel plate 11 to prevent leakage during the pouring process. In this embodiment, as shown in FIG. Fig.12 As shown, the total thickness H of the template 61 and the wooden secondary back rib 62 is greater than the width d2 of the second portion 113 exposed outside the waterproof steel plate 11, and the width d2 of the second portion 113 is 100-150 mm.

[0087] It is worth noting that when the inner support beam 2 and the crown beam 4 are obliquely intersected, Figures 19 to 21 As shown, the second part 113 of the water-stop steel plate 11 is located at the opposite ends of the reserved support beam 1, and is bent along the reserved support beam edge 13 to be perpendicular to the construction joint 14, and is reinforced to ensure the waterproof and anti-seepage performance of the basement exterior wall. Fig.21 As shown, the reserved support beam edge line 13 is the folding line of the water-stopping steel plate 11 , and the water-stopping steel plates on both sides of the reserved support beam 1 are bent along the folding line until they are perpendicular to the construction joint 14 and then reinforced.

[0088] In this embodiment, if Fig. 9 As shown, the tension screw 64 adopts a three-section structure, including an outer tension screw rod 641 that penetrates the formwork 61 and an inner tension screw rod 642 that is buried in the inner support beam 2 or the basement outer wall 3, and both ends of the inner tension screw rod 642 are connected to the outer tension screw rod 641 through a steel sleeve 643; by adopting a three-section tension screw to reinforce the formwork of the inner support beam and the basement outer wall, it is convenient for the later demolding construction, and is also beneficial for the later wall repair and waterproofing construction.

[0089] It is worth noting that if Fig. 9 , Fig.11As shown, the embedded horizontal reinforcement 15 of the basement exterior wall located at the position of the reserved support beam 1 is used as the inner rod of the tension screw, and is connected to the outer rod 641 of the tension screw through the horizontal reinforcement sleeve 151; when the diameter of the outer rod 641 of the tension screw and the embedded horizontal reinforcement 15 of the basement exterior wall are different, the horizontal reinforcement sleeve 151 adopts a reducing sleeve to ensure the connection. After the template is installed and reinforced, the end of the horizontal reinforcement sleeve 151 is in close contact with the template 61; after the concrete of the inner support beam is poured, the outer rod 641 of the tension screw is removed, and the embedded horizontal reinforcement 15 of the basement exterior wall and the horizontal reinforcement sleeve 151 are retained for connecting the horizontal reinforcement 32 of the basement exterior wall. By using the embedded horizontal reinforcement and horizontal reinforcement sleeve of the basement exterior wall to connect with the outer rod of the tension screw to form a three-section tension screw, after the concrete of the inner support beam is poured, the outer rod of the tension screw is removed, and the embedded horizontal reinforcement and horizontal reinforcement sleeve of the basement exterior wall are retained, which not only saves the materials of the tension screw and reduces the construction cost, but also shortens the construction time and improves the construction efficiency.

[0090] Step 6: pouring concrete for inner support beam;

[0091] See also Figure 4 As shown, a steel mesh 7 is installed on both sides of the basement outer wall edge 31 to form a basement outer wall concrete pouring section 34 outside the basement outer wall edge 31; since the basement outer wall concrete has an anti-seepage requirement, the basement outer wall strength is generally higher than the inner support beam concrete strength. To meet the basement outer wall concrete requirements, a steel mesh 7 for separating ordinary concrete and anti-seepage concrete is installed on both sides of the basement outer wall edge 31 to isolate the different concrete between the basement outer wall 3 and the inner support beam 2, and the basement outer wall concrete pouring section 34 is poured with anti-seepage concrete. Therefore, the basement outer wall concrete pouring section is first poured with the same concrete as the basement outer wall, and then the inner support beam section outside the basement outer wall concrete pouring section is poured with the inner support beam concrete.

[0092] Step 7: Construction of internal support;

[0093] See also Fig.13 As shown, after the inner support beam 2 is demolded, square timber secondary back ribs 67 are installed on both sides of the waterstop steel plate 11 and reinforced to protect the waterstop steel plate 11; specifically, the square timber secondary back ribs 67 are arranged close to both sides of the reserved support beam 1, and the tension screw outer rod 641 is connected to the pre-buried horizontal steel bar 15 of the basement outer wall through the horizontal steel bar sleeve 151 to form a tension screw 64, and the tension screw 64 is fixed to the square timber secondary back ribs 67 through mountain clips and nuts. The thickness h of the square timber secondary back ribs 67 is greater than or equal to the width d2 of the second part 113 exposed outside the waterstop steel plate 11, so as to protect the waterstop steel plate 11 and prevent the waterstop steel plate 11 from being damaged by the pile driver during earth excavation and other operations. In this embodiment, Fig.13As shown, the thickness h of the square timber secondary back rib 67 is equal to the width d2 of the second portion 113 exposed outside the water-stop steel plate 11, and the width d2 of the second portion 113 is 100-150 mm.

[0094] Step 8: Connect the horizontal reinforcement of the basement exterior wall and the vertical reinforcement of the basement exterior wall;

[0095] After the basement exterior wall below the inner support is completed to the inner support elevation, the contact surface between the inner support beam and the basement exterior wall is roughened with concrete, and after the foaming agent foam in the horizontal steel sleeve 151 and the vertical steel sleeve 161 is cleaned, the horizontal steel sleeve 151 is used to extend the horizontal steel sleeve 32 of the basement exterior wall, and the vertical steel sleeve 161 is used to extend the vertical steel sleeve 33 of the basement exterior wall; Fig.15 As shown, the diameter of the pre-buried basement exterior wall horizontal steel bar 15 is the same as that of the basement exterior wall horizontal steel bar 32, and the diameter of the pre-buried basement exterior wall vertical steel bar 16 is the same as that of the basement exterior wall vertical steel bar 33. After the steel bars are connected, the basement exterior wall structural steel bars and the reserved support beam structural steel bars can be pulled through to form a complete through-length steel bar.

[0096] Step 9: Construction of basement exterior wall structure;

[0097] See also Figures 16 to 18 As shown in the figure, after the horizontal reinforcement of the basement exterior wall and the vertical reinforcement of the basement exterior wall are extended, a three-section water-stop screw is used to reinforce the basement exterior wall with formwork installation, and then the basement exterior wall is poured; Fig.18 As shown, the formwork is pressed tightly against the inner support beam to prevent leakage.

[0098] Step 10: Remove the inner support beams.

[0099] After the construction of the basement structure above the inner support is completed, the inner support beam 2 is removed. After the inner support beam 2 is cut and removed, the main reinforcement sleeve 121 is removed, and a waterproof mortar protective layer is filled in the remaining position in the main reinforcement sleeve 121 to prevent the steel bars from rusting from the outside to the inside.

[0100] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should fall within the scope of the claims of the present invention.

Claims

1. A method for constructing a foundation pit concrete internal support post-dismantling structure, characterized in that: The following steps are involved: Step 1: Construction preparation; Cut and manufacture a water-stop steel plate according to the cross-sectional dimensions of the reserved support beam, and open a through hole on the water-stop steel plate for the main reinforcement of the reserved support beam to pass through; Step 2: pouring the inner support cushion layer; After positioning and laying out the basement exterior wall and the waterproof steel plate, pour the inner support cushion layer, and leave an installation seam for the waterproof steel plate on the cushion layer; Step 3: Install the inner support beam reinforcement and water stop steel plate; First, the main reinforcement of the reserved support beam and the water-stop steel plate are installed and embedded in the reserved support beam at the same time, and at least part of the water-stop steel plate extends out of the reserved support beam and surrounds the outside of the reserved support beam; then, the main reinforcement of the inner support beam is extended by the main reinforcement sleeves connected at both ends of the main reinforcement of the reserved support beam, and the stirrups of the inner support beam are installed; Step 4: Pre-embed the horizontal reinforcement of the basement exterior wall and the vertical reinforcement of the basement exterior wall; Install the embedded horizontal reinforcement of the basement exterior wall and the embedded vertical reinforcement of the basement exterior wall in the reserved support beam. The embedded horizontal reinforcement of the basement exterior wall is connected with a horizontal reinforcement sleeve, and both ends of the embedded vertical reinforcement of the basement exterior wall are connected with a vertical reinforcement sleeve; Step 5: Install the inner support beam formwork; The inner support beam is reinforced by installing formwork, and is installed in sections on both sides of the waterstop steel plate according to the position of the waterstop steel plate to clamp the waterstop steel plate; Step 6: pouring concrete for inner support beam; Install wire mesh on both sides of the basement outer wall edge line to form a basement outer wall concrete pouring section outside the basement outer wall edge line; first pour the basement outer wall concrete pouring section with concrete consistent with the basement outer wall, and then pour the inner support beam section outside the basement outer wall concrete pouring section with inner support beam concrete; Step 7: Construction of internal support; After the inner support beam is removed from the formwork, square timber back ribs are installed on both sides of the waterstop steel plate and reinforced to protect the waterstop steel plate; Step 8: Connect the horizontal reinforcement of the basement exterior wall and the vertical reinforcement of the basement exterior wall; The horizontal reinforcement of the basement exterior wall is extended through the horizontal reinforcement sleeve, and the vertical reinforcement of the basement exterior wall is extended through the vertical reinforcement sleeve; Step 9: Construction of basement exterior wall structure; After the horizontal reinforcement of the basement exterior wall and the vertical reinforcement of the basement exterior wall are extended, the template is installed and reinforced on the basement exterior wall, and then the basement exterior wall is poured. The template is tightly pressed against the inner support beam to prevent leakage; Step 10: Remove the inner support beams.

2. The method for constructing a foundation pit concrete internal support post-dismantling structure according to claim 1, characterized in that: The water-stop steel plate is a rectangular water-stop ring with an opening in the middle, and the rectangular water-stop ring is made of a steel plate with a thickness of 3-5 mm and is galvanized before being embedded; the water-stop steel plate includes a first part embedded in the reserved support beam and a second part surrounding the outside of the reserved support beam, the width of the four sides of the first part is 100-150 mm, and the width of the four sides of the second part is 100-150 mm; the through holes are arranged at intervals on the first part and the hole diameter thereof is 4-5 mm larger than the diameter of the main reinforcement of the reserved support beam; When the inner support beam and the crown beam are obliquely intersected, the opposite ends of the second part located on both sides of the reserved support beam are bent along the edge line of the reserved support beam to be perpendicular to the construction joint.

3. The method for constructing a foundation pit concrete internal support post-dismantling structure according to claim 1, characterized in that: Step 1 also includes: The threads of the main reinforcement of the inner support beam are made for threaded connection with the main reinforcement sleeve. The two ends of the main reinforcement of the inner support beam are straight threaded and galvanized. The threads of the horizontal reinforcement of the basement exterior wall are made for threaded connection with the horizontal reinforcement sleeve. The threads of the vertical reinforcement of the basement exterior wall are made for threaded connection with the vertical reinforcement sleeve.

4. The method for constructing a foundation pit concrete internal support post-dismantling structure according to claim 2, characterized in that: Before pouring the cushion layer of the inner support beam in step 2, the cushion layer under the reserved support beam is excavated and thickened, and the thickness of the cushion layer under the reserved support beam is greater than or equal to the width of the second part of the waterstop steel plate; after pouring the cushion layer, the basement outer wall edge line and the waterstop steel plate are accurately positioned and laid out on the cushion layer for subsequent pre-embedding.

5. The method for constructing a foundation pit concrete internal support post-dismantling structure according to claim 1, characterized in that: In step three, the main reinforcement of the reserved support beam passes through the through hole of the water-stop steel plate and is then circumferentially welded to seal the gap between the main reinforcement of the reserved support beam and the through hole; the length of the main reinforcement of the reserved support beam is about 10 mm shorter than the thickness of the basement outer wall.

6. The method for constructing a foundation pit concrete internal support post-dismantling structure according to claim 1, characterized in that: The total length of the embedded horizontal steel bars of the basement exterior wall and the two end horizontal steel bar sleeves in step 4 is equal to the horizontal length of the reserved support beam section; the total length of the embedded vertical steel bars of the basement exterior wall and the two end vertical steel bar sleeves is equal to the vertical length of the reserved support beam section; the horizontal steel bar sleeves and the vertical steel bar sleeves are both filled with foaming agent.

7. The method for constructing a foundation pit concrete internal support post-dismantling structure according to claim 2, characterized in that: The specific operations of step five are: Formwork, wooden secondary back ribs and steel pipe main back ribs are installed in sequence on both sides of the inner support beam. The wooden secondary back ribs are arranged at intervals on the outside of the formwork and extend along the length direction of the formwork. Two steel pipe main back ribs form a group, and multiple groups of steel pipe main back ribs are arranged at intervals on the outside of the wooden secondary back ribs and extend along the width direction of the formwork. After the tension screws pass through the formwork, the steel pipe main back ribs and wooden secondary back ribs are fixed by mountain clips and nuts. The formwork and wooden secondary back ribs on both sides of the waterstop steel plate clamp the waterstop steel plate.

8. The method for constructing a foundation pit concrete internal support post-dismantling structure according to claim 7, characterized in that: The tension screw adopts a three-section structure, including an inner tension screw rod and an outer tension screw rod connected to both ends of the inner tension screw rod, and the outer tension screw rod is connected to the inner tension screw rod through a steel sleeve; The embedded horizontal reinforcement of the basement exterior wall located at the reserved support beam position is used as the inner rod of the tension screw, and the outer rod of the tension screw is connected through the horizontal reinforcement sleeve; after the template is installed and reinforced, the end of the horizontal reinforcement sleeve is in close contact with the template; after the concrete of the inner support beam is poured, the outer rod of the tension screw is removed, and the embedded horizontal reinforcement of the basement exterior wall and the horizontal reinforcement sleeve are retained for connecting the horizontal reinforcement of the basement exterior wall; In the case that the diameters of the outer rod of the tension screw rod and the horizontal steel bars of the pre-buried basement outer wall are different, the horizontal steel bar sleeve adopts a reducing sleeve to ensure the connection.

9. The method for constructing a foundation pit concrete internal support post-dismantling structure according to claim 8, characterized in that: After the inner support beam is demolded in step seven, the outer rod of the tension screw penetrates the secondary back rib of the square wood and is connected to the embedded horizontal steel bars of the basement outer wall through the horizontal steel bar sleeve to form a tension screw, and the tension screw is fixed to the secondary back rib of the square wood by a mountain-shaped clip and a nut; the thickness of the secondary back rib of the square wood is greater than or equal to the width of the second part of the waterstop steel plate.

10. The method for constructing a foundation pit concrete internal support post-dismantling structure according to claim 1, characterized in that: The specific operation of step eight is as follows: after the basement exterior wall below the inner support is completed to the inner support elevation, the contact surface between the inner support beam and the basement exterior wall is roughened with concrete, the foaming agent foam in the horizontal steel bar sleeve and the vertical steel bar sleeve is cleaned, and the horizontal steel bars of the basement exterior wall and the vertical steel bars of the basement exterior wall are connected. After the steel bars are extended, the structural steel bars of the basement exterior wall and the reserved supporting beam structural steel bars are pulled through to form a complete through-length steel bar; The specific operation of step ten is: after the construction of the basement structure above the internal support is completed, the internal support beam is removed, and after the internal support beam is cut and removed, the main reinforcement sleeve is removed, and the position left in the main reinforcement sleeve is filled with a waterproof mortar protective layer to prevent the steel bar from rusting from the outside to the inside.

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