Underground shear wall post-cast strip construction method

Abstract

The invention discloses a construction method for a post-cast strip of an underground shear wall. The construction method comprises the following steps: S1, constructing a raft foundation; s2, shear wall construction; s3, post-cast strip water stop structure construction, wherein a water stop structure of an arch ring structure is built on the outer side of the post-cast strip area of the shear wall, and waterproof layer operation and earthwork backfilling operation are conducted on the outer side of the water stop structure; s4, post-cast strip construction is conducted, specifically, after post-cast strip formworks are manufactured and installed in the post-cast strip area, concrete pouring of the post-cast strip area is completed; according to the post-cast strip water stop structure, the waterproof effect of the post-cast strip is enhanced, corrosion of steel bars in the post-cast strip and water accumulation of a basement caused by permeation before the post-cast strip of the basement is sealed are avoided, the rainfall construction amount can be reduced, the construction time is saved, the engineering quality is improved, and the engineering construction difficulty is reduced; and meanwhile, the post-cast strip is sealed through the post-cast strip water stop structure, so that construction period delay caused by post-cast strip construction intermittence can be reduced, and basement exterior wall waterproof layer construction and foundation pit backfilling earthwork operation are carried out in advance.

Description

Technical Field

[0001] The invention relates to the technical field of building construction, and in particular to a construction method for a post-cast strip of an underground shear wall. Background Art

[0002] Shear walls, also known as wind-resistant walls, earthquake-resistant walls, or structural walls, are walls in buildings or structures that primarily bear horizontal and vertical loads (gravity) caused by wind or earthquakes, preventing structural shear damage. They are also called earthquake-resistant walls and are generally made of reinforced concrete. Post-cast joints are temporary construction joints created in the foundation slab, walls, and beams during construction to prevent harmful cracks caused by uneven shrinkage or settlement of cast-in-place reinforced concrete structures. These joints, as required by design or construction specifications, temporarily divide the structure into several sections. After the components shrink, concrete is poured in these joints later in construction to connect the structure as a whole.

[0003] As modern construction sees an increasing number of high-rise and super-high-rise buildings, their basements are becoming deeper and deeper, and their structures are becoming increasingly complex. Basement floors and walls have many post-cast strips, and installing traditional post-cast strips will inevitably cause rainwater and groundwater to enter the basement before the post-cast strips are sealed. This requires continuous dewatering of the basement, which significantly increases dewatering costs and project costs when the main building construction takes a long time. At the same time, due to the construction period constraints of post-cast strips, side wall waterproofing, and superstructures, the underground space cannot be backfilled in advance, and the risk of foundation pit collapse has not been eliminated. Furthermore, whether the superstructure construction uses a floor-standing frame (dropped to the bottom of the foundation pit) or a cantilevered frame, the cost will increase to varying degrees and affect the subsequent construction of outdoor pipe networks.

[0004] Therefore, how to simultaneously meet the requirements of structural deformation and waterproofing before pouring the post-cast zone concrete is a relatively contradictory problem in the construction of high-rise buildings and super-long buildings. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a construction method for underground shear wall post-cast strips. By adopting this method, earth backfilling can be carried out immediately after the construction of the underground space is completed, reducing the safety hazards of deep foundation pits and achieving an ideal overall waterproofing effect.

[0006] The present invention provides a construction method for an underground shear wall post-cast strip, comprising the following steps:

[0007] S1. Raft foundation construction: Prepare the raft base within the construction area and complete the pouring of the raft cushion. After surveying and setting out, tie the raft reinforcement and insert the shear wall reinforcement. Then, pour the raft concrete.

[0008] S2. Shear wall construction: Tie the shear wall reinforcement to the raft foundation, then install and reinforce the shear wall formwork. Reserve the post-casting zone. Finally, pour concrete in all areas of the shear wall, excluding the post-casting zone.

[0009] S3. Construction of post-cast strip waterstop structure: Build an arch-shaped post-cast strip waterstop structure outside the post-cast strip area of the shear wall. Then, perform waterproofing and backfill work on the outside of the post-cast strip waterstop structure.

[0010] S4. Construction of post-casting strip: After the post-casting strip formwork is made and installed in the post-casting strip area, the concrete pouring in the post-casting strip area is completed.

[0011] Furthermore, in step S1, the raft reinforcement binding operation specifically includes: installing and fixing the raft waterstop steel plate located in the post-cast zone area, installing and fixing the raft waterstop structure, and installing the side closing net of the post-cast zone.

[0012] Furthermore, in step S2, the shear wall reinforcement binding operation specifically includes the installation and fixation of the water-stop steel plate in the shear wall post-cast zone area and the installation of the side closing template of the shear wall post-cast zone.

[0013] Furthermore, in step S2, it also includes the shear wall formwork removal operation and shear wall maintenance operation after the shear wall concrete is poured.

[0014] Further, in step S3, the post-cast strip water-stop structure includes an arch ring brick wall formed by cement bricks and cement mortar to form an arch ring structure, and the width of the arch ring brick wall is greater than the width of the post-cast strip and is located outside the post-cast strip area of the shear wall.

[0015] Furthermore, in step S3, the waterproof layer operation includes a cement mortar plastering layer operation provided on the outer surface of the arch ring brick wall and an asphalt waterproof membrane layer operation provided outside the cement mortar plastering layer.

[0016] Furthermore, the asphalt waterproofing membrane layer is formed by stacking at least two layers of asphalt waterproofing membrane, and both ends of the asphalt waterproofing membrane layer in the length direction extend to the shear walls on the corresponding sides respectively.

[0017] Furthermore, during the construction of the raft foundation, the raft foundation partially extends outwards to the post-cast strip water-stop structure in the post-cast strip area and forms the foundation of the post-cast strip water-stop structure.

[0018] Furthermore, in step S4, it also includes backfilling the internal cavity of the water-stop structure of the post-cast zone before pouring the concrete of the post-cast zone.

[0019] Furthermore, in step S4, it also includes the operation of removing the formwork of the post-casting strip after the post-casting strip concrete is poured and the operation of curing the post-casting strip.

[0020] The present invention has the following beneficial effects:

[0021] (1) The water-stop structure of the post-cast strip in the present invention enhances the waterproof effect of the post-cast strip, avoids the corrosion of steel bars in the post-cast strip and water accumulation in the basement caused by infiltration before the post-cast strip is closed, reduces the amount of precipitation construction, saves construction time, improves project quality, and reduces the difficulty of project construction.

[0022] (2) The present invention closes the post-cast strip through the post-cast strip water-stop structure, which can reduce the construction delay caused by the interruption of the post-cast strip construction, and enable the construction of the basement exterior wall waterproofing layer and the foundation pit backfilling operation to be carried out in advance, thereby providing conditions for the subsequent overall layout and ground procedures.

[0023] (3) After the construction of the post-casting zone water-stop structure is completed, the fertilizer trough can be backfilled in advance to reduce the exposure time of the foundation pit, reduce the risk of foundation pit collapse, and facilitate construction safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0025] Figure 1 It is a structural schematic diagram of the raft foundation in the present invention;

[0026] Figure 2 This is a structural diagram of the connection between the post-cast strip water-stop structure and the shear wall in the present invention;

[0027] Figure 3 This is a schematic diagram of the template at the post-cast zone of the shear wall in the present invention;

[0028] Figure 4 It is a construction process flow chart of the present invention;

[0029] Explanation of the accompanying symbols: 1-raft cushion layer; 2-raft waterproof layer; 3-rubber waterstop; 4-raft foundation steel structure; 5-shear wall bottom plate; 6-raft waterstop steel plate; 7-post-cast strip; 8-shear wall; 9-shear wall steel structure; 10-tensioned rod; 11-shear wall waterstop steel plate; 12-arch brick wall; 13-cement mortar plaster layer; 14-asphalt waterproof membrane layer; 15-facing plywood; 16-reinforced steel pipe; 17-waterstop bolt; 18-water flow direction. DETAILED DESCRIPTION

[0030] This application proposes a construction method for underground shear wall post-casting strips, comprising the following steps:

[0031] S1. Raft foundation construction: The raft base within the construction area is processed and the raft cushion layer 1 is poured. After measuring and setting out, the raft reinforcement is tied and the shear wall 8 is inserted, followed by the raft concrete pouring. The raft reinforcement tying operation specifically includes: the installation and fixation of the raft waterstop steel plate 6 located in the post-cast zone 7 area, the installation and fixation of the raft waterstop structure, and the installation of the side closing net of the post-cast zone 7.

[0032] S2. Shear wall 8 construction: Tie the shear wall reinforcement structure 9 to the raft foundation. Then, install and reinforce the shear wall 8 formwork. Reserve the post-casting strip 7 area. Finally, pour concrete in all areas of the shear wall 8 except the post-casting strip 7 area.

[0033] S3 post-casting belt 7 water-stop structure construction: in the shear wall 8 of the post-casting belt 7 area outside the masonry arch structure of the post-casting belt 7 water-stop structure, and post-casting belt 7 water-stop structure outside the waterproof layer operation and earth backfill operation;

[0034] S4. Construction of post-casting strip 7: After the post-casting strip 7 formwork is made and installed in the post-casting strip 7 area, the concrete pouring in the post-casting strip 7 area is completed.

[0035] In this embodiment, in step S1, before the raft foundation reinforcement structure 4 is tied (including the installation and fixation of the raft water-stop steel plate 6) and the raft water-stop steel plate 6 is installed and fixed, the raft cushion layer 1 should be poured and its surface should be leveled and polished, otherwise it will affect the waterproof effect of the subsequent raft waterproof structure. Then the measurement and layout work is carried out. Before laying out the lines, it is required to carefully review the drawings and clarify the design intention before proceeding to the next step. It is mainly used to determine the position of the post-cast strip 7 and the specifications for laying. Then the raft water-stop structure is installed and fixed, combined with Figure 1 As shown, the raft water stop structure includes a raft waterproof layer 2 and a rubber water stop 3, wherein the raft waterproof layer 2 is made of two layers of polymer modified asphalt waterproof membrane, and the rubber water stop 3 is as shown in FIG. Figure 1As shown, it mainly utilizes the high elasticity of rubber to produce elastic deformation under various loads, thereby playing a strong seal, effectively preventing water leakage and seepage in the building structure, and playing a shock-absorbing and buffering role. The specific material of the rubber waterstop 3 should be selected taking into account the corrosion effect of the medium to be contacted (such as acid, alkali, salt, oil, solvent and various corrosive gases) on the waterstop. For example, when encountering weak acid and alkali corrosive media, it is appropriate to use chloroprene rubber waterstop 3, and when encountering oil corrosive media, it is appropriate to use nitrile rubber waterstop 3, etc. This is existing technology and will not be repeated here. When installing the rubber waterstop 3, the installation method of overlapping first and then fixing is adopted. The main advantage is that the overlapping joint has the advantages of large contact area, strong bonding ability and good sealing effect. When overlapping, due to the appearance characteristics of the concave and convex structure of the rubber waterstop 3, simple overlapping laying cannot guarantee the construction quality. In addition, the groove in the middle is its effective waterproof area, and it is necessary to ensure that the concrete and the groove fit tightly. Before overlapping, first use a knife to cut off the protruding part of the rubber waterstop 3, then use a file to make a fresh surface on the bonding surface of the two rubber waterstops 3 to be bonded, and clean the bonding surface with gasoline. , and then evenly apply a special high-strength rubber adhesive on the bonding surface. After the two rubber waterstops 3 are bonded, hammer them with a rubber hammer to make the bonding parts as fully contact as possible and minimize the gaps. Then use a special clamp to clamp the overlapping parts. Remove the clamp after 30 minutes. The overlapping length is not less than 100mm to fully ensure its waterproof effect. At the same time, the horizontal rubber waterstop 3 is located on the raft cushion layer 1. Due to the effect of gravity, it can be well placed on the raft. Nails and other sharp objects cannot be used for fixing, otherwise it will cause incompleteness of the rubber waterstop 3 and affect the waterproof effect.

[0036] Then, according to the position of the rubber waterstop 3, use paint to draw a position mark line at the center line of the rubber waterstop 3, and at the same time, put out the position line of the raft foundation steel structure 4, which can avoid the displacement of the rubber waterstop 3 during installation, and also facilitate the verification of the rubber waterstop 3 and the steel bar position; then according to the requirements of the drawing, complete the steel bar binding at one time, requiring the joints to be staggered by 50% in the same section, and minimize the number of joints on the same steel bar; the side closing net of the post-cast strip 7 must be installed firmly to prevent concrete from flowing into the post-cast strip 7; after the shear wall 8 reinforcement operation is completed, the raft concrete pouring construction is carried out.

[0037] In this embodiment, in step S2, the binding of the shear wall reinforcement structure 9 specifically includes the installation and fixation of the waterstop steel plate in the post-casting strip 7 area and the installation of the side closing template of the post-casting strip 7. After the raft slab concrete is poured, the binding of the shear wall reinforcement structure 9 and the installation and fixation of the shear wall waterstop steel plate 11 begin. The shear wall waterstop steel plate 11 should be located in the center of the post-casting strip 7, with the groove surface facing the direction of water flow. An L-shaped Φ12 steel support frame is used, with the short side welded to the shear wall waterstop steel plate 11 and the long side welded to the shear wall reinforcement structure 9. The support spacing is ≤200mm, and the length of the support steel bar must match the wall thickness to avoid excessive length forming a seepage channel. The waterstop steel plate of the post-casting strip 7 must be continuously welded to the raft slab waterstop steel plate 6 in an inverted T-shape or L-shape to ensure a seal. At the same time, the side closing net of the post-casting strip 7 must be firmly installed to prevent concrete from flowing into the post-casting strip 7. Installation of the closing formwork: The side closing of the post-casting strip 7 is completed with a serrated formwork. The side of the closing formwork facing away from the post-casting strip 7 is securely tied to the shear wall reinforcement structure 9 with wire. The side facing the post-casting strip 7 is supported by wooden beams to prevent leakage or formwork explosion during concrete pouring, ensuring the quality of concrete pouring on both sides of the post-casting strip 7. After the closing formwork is removed, the concrete at the closing location is manually roughened.

[0038] In this embodiment, in step S3, the post-cast strip 7 water-stopping structure includes an arch ring brick wall 12 formed by cement bricks and cement mortar to form an arch ring structure, and the width of the arch ring brick wall 12 is greater than the width of the post-cast strip 7 and is located outside the post-cast strip 7 area of the shear wall 8; the waterproof layer operation includes the operation of a cement mortar plastering layer 13 arranged on the outer ring surface of the arch ring brick wall 12 and the operation of an asphalt waterproof membrane layer 14 arranged outside the cement mortar plastering layer 13; during the construction of the raft foundation, the raft foundation partially extends outward to the post-cast strip 7 water-stopping structure in the post-cast strip 7 area and forms the foundation of the post-cast strip 7 water-stopping structure.

[0039] The raft foundation partially extends outward at the post-casting strip 7 to the bottom of the water-stop structure of the post-casting strip 7, forming the foundation of the arch ring brick wall 12. After the concrete pouring of the shear wall 8 is completed and the formwork system is removed and cleaned, the foundation surface is roughened and rinsed clean. Subsequently, a 240mm thick arch ring brick wall 12 is built outside the post-casting strip 7 in the underground space. The arch ring brick wall 12 is built with MU10 cement bricks and M7.5 cement mortar, and tie rods 10 for fixing the formwork are pre-embedded in the horizontal section wall at a spacing of 400mm×400mm in both horizontal and vertical directions to fix the formwork during the pouring of the post-casting strip 7. After the arch ring brick wall 12 is built, it is plastered in two steps to form a cement mortar plaster layer 13 to ensure a smooth surface for the construction of waterproof membrane.

[0040] After the arch ring brick wall 12 is plastered, the waterproof layer (including the waterproof reinforcement layer) is constructed. The waterproof layer is also made of two layers of polymer-modified asphalt waterproof membrane to ensure that the waterproof membrane construction quality meets the qualified standards. The asphalt waterproof membrane layer 14 is formed by stacking at least two layers of asphalt waterproof membrane, and the two ends of the asphalt waterproof membrane layer 14 in the longitudinal direction extend to the shear wall 8 on the corresponding side to improve the waterproof effect. The waterproof reinforcement layer (30mm extruded polystyrene board) is then pasted. After the arch ring brick wall 12 in the underground space post-cast zone 7 reaches the design strength, the fertilizer trough backfill construction begins. Thickness of virtual paving: ≤300mm when compacted mechanically, ≤200mm when compacted manually. Use light compacting equipment such as flat plate compactors or wooden compactors within the range of 1000mm close to the arch ring brick wall 12 (to avoid damaging the arch ring brick wall 12). Symmetrical backfill and compaction should be adopted within 500mm on both sides of the arch ring brick wall 12, with a height difference of ≤300mm to avoid unilateral extrusion that may cause the arch ring brick wall 12 to shift or crack, or damage the waterproof layer.

[0041] In this embodiment, step S4 also includes backfilling the internal cavity of the water-stop structure of the post-cast strip 7 before the concrete of the post-cast strip 7 is poured. Before the concrete of the post-cast strip 7 is poured, the template of the post-cast strip 7 is first installed. Before the template is installed, the debris in the post-cast strip 7 is cleared and the position of the steel bars is corrected. If necessary, the steel bars are treated with anti-rust treatment and the template can be installed only after passing the inspection by the supervisor. The template of the post-cast strip 7 adopts 14mm thick facing plywood 15. A reinforcing steel pipe 16 is provided on the side of the template of the post-cast strip 7 away from the post-cast strip 7. Since the tie rod 10 is preset before the shear wall 8 is poured and the arch ring brick wall 12 is built, the water stop bolt 17 can be connected to the tie rod 10 before closing the mold to achieve single-sided formwork fixation. Before pouring the concrete of the post-cast strip 7, the cavity of the arch ring brick wall 12 is backfilled with clay or sand; to ensure the waterproof effect, a higher strength grade of compensating shrinkage concrete is used for pouring the post-cast strip 7, and a combined structure of a boom pump and a placing boom is used to assist in concrete pouring to meet the requirements of long-distance concrete transportation and improve construction efficiency.

[0042] In this embodiment, step S4 also includes the formwork removal operation of the post-casting strip 7 and the curing operation of the post-casting strip 7 after the concrete of the post-casting strip 7 is poured; after the concrete of the post-casting strip 7 reaches initial setting, secondary polishing is performed, and concrete curing work is carried out, and the curing time is not less than 14 days.

[0043] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A construction method for underground shear wall post-casting strip, characterized by: The steps include: S1. Raft foundation construction: Prepare the raft base within the construction area and complete the pouring of the raft cushion. After surveying and setting out, tie the raft reinforcement and insert the shear wall reinforcement. Then, pour the raft concrete. S2. Shear wall construction: Tie the shear wall reinforcement to the raft foundation, then install and reinforce the shear wall formwork. Reserve the post-casting zone. Finally, pour concrete in all areas of the shear wall, excluding the post-casting zone. S3. Construction of post-cast strip waterstop structure: Build an arch-shaped post-cast strip waterstop structure outside the post-cast strip area of the shear wall. Then, perform waterproofing and backfill work on the outside of the post-cast strip waterstop structure. S4. Construction of post-casting strip: After the post-casting strip formwork is made and installed in the post-casting strip area, the concrete pouring in the post-casting strip area is completed.

2. The method for constructing an underground shear wall post-casting strip according to claim 1, characterized in that: In step S1, the raft slab reinforcement binding operation specifically includes: installing and fixing the raft slab waterstop steel plate located in the post-cast zone area, installing and fixing the raft slab waterstop structure, and installing the side closing net of the post-cast zone.

3. The construction method of underground shear wall post-casting strip according to claim 1, characterized in that: In step S2, the shear wall reinforcement binding operation specifically includes the installation and fixation of the water-stop steel plate in the shear wall post-cast zone area and the installation of the side closing template of the shear wall post-cast zone.

4. The method for constructing an underground shear wall post-casting strip according to claim 3, characterized in that: In step S2, the shear wall formwork removal operation and shear wall maintenance operation are also included after the shear wall concrete is poured.

5. The method for constructing underground shear wall post-casting strips according to claim 1, characterized in that: In step S3, the post-cast strip water-stop structure includes an arch ring brick wall formed by cement bricks and cement mortar to form an arch ring structure. The width of the arch ring brick wall is greater than the width of the post-cast strip and is located outside the post-cast strip area of the shear wall.

6. The method for constructing an underground shear wall post-casting strip according to claim 5, characterized in that: In step S3, the waterproof layer operation includes the operation of setting a cement mortar plaster layer on the outer surface of the arch ring brick wall and the operation of setting an asphalt waterproof membrane layer outside the cement mortar plaster layer.

7. The method for constructing underground shear wall post-casting strips according to claim 6, characterized in that: The asphalt waterproofing membrane layer is formed by stacking at least two layers of asphalt waterproofing membrane, and both ends of the asphalt waterproofing membrane layer in the length direction extend to the shear walls on the corresponding sides respectively.

8. The method for constructing underground shear wall post-casting strips according to claim 1, characterized in that: During the construction of the raft foundation, the raft foundation partially extends outwards to the post-cast strip water-stop structure at the post-cast strip area and forms the foundation of the post-cast strip water-stop structure.

9. The method for constructing underground shear wall post-casting strips according to claim 1, characterized in that: In step S4, it also includes backfilling the internal cavity of the water-stop structure of the post-cast zone before pouring the concrete of the post-cast zone.

10. The method for constructing underground shear wall post-casting strips according to claim 9, characterized in that: In step S4, it also includes the operation of removing the formwork of the post-casting strip after the post-casting strip concrete is poured and the operation of curing the post-casting strip.

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