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CN-121976543-A - Municipal engineering deep foundation pit supporting structure and construction method

CN121976543ACN 121976543 ACN121976543 ACN 121976543ACN-121976543-A

Abstract

The application relates to a municipal engineering deep foundation pit supporting structure and a construction method, and relates to the technical field of geotechnical engineering and building construction. The application integrates the supporting piles, the waterproof curtain, the anchor ropes, the inner support and the waterproof wall into an organic integral supporting system, the supporting piles and the occlusion waterproof curtain form a first structure-waterproof integrated defense line, the anchor ropes and the inner support provide horizontal resistance in stages and areas according to the excavation depth, a composite supporting mechanism of 'pulling before top and hardness and softness and economy' is formed, and the multi-channel supporting system greatly improves the overall stability and safety redundancy of deep foundation pit engineering and can effectively cope with various complex working conditions and unexpected loads.

Inventors

  • LIU XIAOXIA
  • WANG XUEJIN
  • CHEN SUTING

Assignees

  • 广东弘海实业发展有限公司

Dates

Publication Date
20260505
Application Date
20260330

Claims (9)

  1. 1. A municipal engineering deep foundation pit supporting structure is characterized by comprising a supporting pile assembly (1), a waterproof curtain assembly (2), a water retaining wall (3), an inner supporting assembly (4) and an anchor rope assembly (5), wherein the supporting pile assembly (1) is formed by arranging a plurality of filling piles at intervals, the waterproof curtain assembly (2) is formed by triaxial cement stirring piles, the triaxial cement stirring piles are meshed with the outer sides of the filling piles to form a continuous closed supporting waterproof wall body, the anchor rope assembly (5) penetrates through soil bodies among piles of the supporting pile assembly (1) and is anchored in a stable stratum, the end portions of the anchor rope assembly are connected with the supporting pile assembly (1) through crown beams (51), and the inner supporting assembly (4) is installed between the crown beams (51) after a foundation pit is excavated to a designed elevation.
  2. 2. The municipal engineering deep foundation pit supporting structure according to claim 1, wherein the pile spacing of the cast-in-place piles in the supporting pile assembly (1) is 400mm, the strength grade of concrete is C30, the longitudinal stress steel bars adopt HRB400 grade steel bars, the spiral stirrups adopt HPB300 grade steel bars, the pile diameter of the triaxial cement mixing piles in the waterproof curtain assembly (2) is 650mm, and the pile-to-pile overlap width is not less than 200mm.
  3. 3. The municipal works deep basal pit supporting structure according to claim 1, characterized in that, anchor rope subassembly (5) include crown roof beam (51), closing cap (52), reinforcing bar sleeve pipe (53), fixed cylinder (54), locking seat (55), lock nut (56), strengthening rib (57), steel strand wires (58), crown roof beam (51) with prop up stake subassembly (1) and be connected, strengthening rib (57) are connected with the upper end bolt of closing cap (52), crown roof beam (51) are fixed with the bottom of fixed cylinder (54), strengthening rib (57) are installed in the inside of reinforcing bar sleeve pipe (53), fixed cylinder (54) are connected with the bottom of locking seat (55), locking seat (55) and the inboard screw-thread fit of lock nut (56), strengthening rib (57) are embedded in the inside of fixed cylinder (54), the slip casting of anchor rope subassembly (5) adopts the secondary slip casting technology.
  4. 4. A deep foundation pit supporting structure for municipal works according to claim 3, wherein the inside of the crown beam (51) and the fixing cylinder (54) are hollow, the steel bar sleeve (53) and the steel strands (58) penetrate through the middle part of the crown beam (51), penetrate through the tops of the fixing cylinder (54) and the locking seat (55), and are embedded into the inner side of the upper end of the reinforcing rib (57).
  5. 5. The municipal works deep basal pit supporting structure according to claim 3, characterized in that, the lower extreme of strengthening rib (57) is provided with fixed cover (571), connection lug (572), all be fixed with connection lug (572) in four corners around strengthening rib (57), fixed cover (571) are fixed with one end that strengthening rib (57) was kept away from to connection lug (572), the inboard of fixed cover (571) is fixed with reinforcing bar sleeve pipe (53).
  6. 6. The municipal works deep basal pit supporting structure according to claim 3, characterized in that, locking seat (55) is including supporting seat (551), spacing seat (552), centre gripping cap (553), the bottom of supporting seat (551) is fixed with fixed section of thick bamboo (54), the top of supporting seat (551) is provided with spacing seat (552), spacing seat (552) is fixed with the bottom of centre gripping cap (553), the lower extreme of centre gripping cap (553) sets up right-hand member external screw thread, lock nut (56) and external screw thread cooperation, the upper end of centre gripping cap (553) comprises the clamp splice of clearance distribution.
  7. 7. A construction method for the deep foundation pit composite support structure according to any one of claims 1 to 6, characterized by comprising the steps of: Step S1, geological rechecking and scheme confirmation before construction, namely checking on-site geological conditions and geotechnical engineering investigation reports, and confirming a supporting design scheme; S2, measuring and positioning, namely accurately lofting the plane positions of the support pile and the triaxial cement mixing pile according to a design drawing; Step S3, constructing the support pile and the waterproof curtain, namely sequentially completing pore forming, pore cleaning, reinforcement cage installation and underwater concrete pouring of the cast-in-situ pile by adopting a pile isolation construction method, and simultaneously or alternatively constructing the triaxial cement mixing pile to ensure that the triaxial cement mixing pile is effectively meshed with the cast-in-situ pile; S4, excavating earthwork in a layered and sectional mode, wherein the excavation thickness of each layer is not more than 1.5m, and the sectional length is not more than 15m; S5, anchor cable construction, namely after the anchor cable is excavated to the designed elevation of the anchor cable, carrying out anchor cable pore forming, steel strand laying and grouting operation, and tensioning and locking the anchor cable on the crown beam (51) after the grouting consolidation body strength reaches 75% of the designed strength; s6, installing an inner support, namely constructing a reinforced concrete inner support assembly (4) after a foundation pit is excavated to a designed bottom layer elevation; And S7, monitoring the deformation of the supporting structure and the underground water level in the whole process, finding out abnormal immediate shutdown treatment, and adjusting the excavation sequence, speed or starting an emergency plan in time when the monitored data is close to or reaches an early warning value.
  8. 8. The construction method of the municipal engineering deep foundation pit supporting structure according to claim 7, wherein in the step S3, the allowable deviation of the perpendicularity of the cast-in-place pile is not more than 1%, the allowable deviation of the pile position is not more than 50mm, the allowable deviation of the perpendicularity of the triaxial cement stirring pile is not more than 1/300, and the allowable deviation of the pile position is not more than 30mm.
  9. 9. The construction method of the municipal engineering deep foundation pit supporting structure according to claim 7, wherein in the step S5, an anchor test is performed before the anchor rope is formally constructed to verify design parameters of the anchor rope, pretension is performed before the anchor rope is tensioned, pretension load is 1.4 times of an axial tension standard value, unloading is performed after 15min, and tensioning is performed until the locking load is achieved.

Description

Municipal engineering deep foundation pit supporting structure and construction method Technical Field The application relates to the technical field of geotechnical engineering and building construction, in particular to a municipal engineering deep foundation pit supporting structure and a construction method. Background The deep foundation pit engineering is a foundation stone for modern urban construction and is widely applied to the fields of high-rise building basements, underground rail transit, comprehensive pipe galleries, underground business development and the like. With the continuous deep urban process, the construction land is increasingly tense, foundation pit engineering is developing towards deeper, larger and closer to the existing building, and the foundation pit engineering has raised unprecedented high standard and stringent requirements on the safety and stability of the supporting structure and the protection capability to the surrounding environment. Aiming at the related technology, in the prior art, deep foundation pit support usually adopts a scheme of pile row support, underground continuous wall, soil nailing wall and combination of various support forms, and the following problems exist: the subsystem such as support, water stop, anchoring and the like is often designed and constructed independently, lacks a cooperative working mechanism as an organic whole, and is difficult to cope with complex working conditions; in complex geology and sensitive environment, the deformation control precision of the traditional support structure and the reliability of the waterproof curtain face serious tests; an inherent contradiction exists between the inner support system and the efficiency of earth excavation and main body construction; The existing anchor cable technology has poor adaptability to bad strata, and large fluctuation of construction quality becomes a potential safety hazard point. Therefore, there is an urgent need in the art for a deep foundation pit supporting structure and construction method that can systematically solve the above problems, integrate efficient supporting, reliable water stopping, accurate anchoring and space optimization, and are suitable for complex geological conditions. Disclosure of Invention The application aims to provide a municipal engineering deep foundation pit supporting structure and a construction method. According to the technical scheme, the deep foundation pit supporting structure for municipal engineering comprises a supporting pile assembly, a waterproof curtain assembly, a water retaining wall, an inner supporting assembly and an anchor rope assembly, wherein the supporting pile assembly is formed by arranging a plurality of filling piles at intervals, the waterproof curtain assembly is formed by triaxial cement mixing piles, the triaxial cement mixing piles are meshed with the outer sides of the filling piles to form a continuous closed supporting waterproof wall body, the anchor rope assembly penetrates through soil bodies among piles of the supporting pile assembly and is anchored in a stable stratum, the end portions of the anchor rope assembly are connected with the supporting pile assembly through crown beams, and the inner supporting assembly is installed between the crown beams after the foundation pit is excavated to a designed elevation. By adopting the technical scheme, the support, the water stop, the anchoring and the inner support are integrated into a system which works cooperatively. The support pile is used as a main stress member and forms a first-path 'structure-waterproof' integrated barrier together with the waterproof curtain meshed with the outer side, so that soil pressure is effectively born and groundwater is blocked. Preferably, the pile spacing of the cast-in-place piles in the support pile assembly is 400mm, the strength grade of concrete is C30, the longitudinal stress steel bars adopt HRB400 level steel bars, the spiral stirrups adopt HPB300 level steel bars, the pile diameter of the triaxial cement mixing pile in the waterproof curtain assembly is 650mm, the overlap joint width between piles is not less than 200mm, the cement mixing amount is not less than 310kg/m < 3 >, 42.5R ordinary silicate cement is adopted, and the water-cement ratio is 1.5. By adopting the technical scheme, the specific parameters of the key components are defined. The pile spacing of 400mm can ensure the stability of soil between piles and prevent soil leakage, and the matching of C30 concrete and HRB400 grade reinforcing steel bars ensures the strength and durability of the support piles. Preferably, the anchor cable assembly comprises a crown beam, a cap, a reinforcing steel sleeve, a fixing cylinder, a locking seat, a locking nut, a reinforcing rib and a steel strand, wherein the crown beam is connected with the support pile assembly, the reinforcing rib is connected with the upper end of the cap through bolts, the crown beam