Large-rigidity foundation pit supporting structure suitable for deep soft soil condition

Abstract

The utility model relates to the technical field of foundation pit construction structures, in particular to a large-rigidity foundation pit supporting structure suitable for deep and thick soft soil conditions, which comprises a double-row pile system, a deformation control built-in area and a drainage structure backfilling area. The double-row pile system consists of front-row cast-in-place piles, rear-row cast-in-place piles and double-row pile connecting beams for connecting the front-row cast-in-place piles and the rear-row cast-in-place piles; a water stopping system is arranged in a gap between the outer walls of the front-row cast-in-place piles and the rear-row cast-in-place piles and soft soil, the water stopping system is a high-pressure jet grouting pile, and the deformation control build-in area is arranged on the inner side of the double-row pile system and composed of meshed high-pressure jet grouting piles at steps, enclosure cast-in-place piles and anchor cables. Wherein the enclosure cast-in-place piles and the occlusion high-pressure jet grouting piles are in occlusion connection in the transverse direction and the longitudinal direction. According to the large-rigidity foundation pit supporting structure suitable for the deep and thick soft soil condition, the water stopping system combining the double-row pile system and the high-pressure jet grouting piles is adopted, water and soil loss around the foundation pit is effectively controlled, and the stability in the foundation pit excavation process is ensured.

Description

Technical Field

[0001] The utility model relates to the technical field of foundation pit construction structures, in particular to a large-rigidity foundation pit supporting structure suitable for thick soft soil conditions. Background Art

[0002] Urban renewal in old urban areas has become an important direction of urban development today. In this process, the development and utilization of underground space has become particularly critical, especially in areas with a small bedrock depth. How to effectively excavate foundation pits and ensure the stability of the surrounding environment has become an urgent problem to be solved.

[0003] When faced with deep soft soil conditions, traditional foundation pit support structures are often unable to meet the needs of fast and safe construction due to their insufficient rigidity. As underground space construction continues to deepen, the challenges faced by foundation pit excavation are also increasing. Especially in deep soft soil conditions, due to the complexity and uncertainty of the soil layer, problems such as soil instability and foundation pit water gushing are very likely to occur during foundation pit excavation, which seriously threatens construction safety and the stability of the surrounding environment. Utility Model Content

[0004] The purpose of the utility model is to provide a high-rigidity foundation pit support structure suitable for deep soft soil conditions, so as to solve the problem that the traditional foundation pit support structure proposed in the above background technology is often difficult to meet the needs of fast and safe construction due to its insufficient rigidity when facing deep soft soil conditions.

[0005] To achieve the above-mentioned purpose, the utility model provides a high-rigidity foundation pit support structure suitable for deep soft soil conditions, including a double-row pile system, a deformation control embedded area and a drainage structure backfill area, the double-row pile system is composed of a front-row cast-in-place pile, a rear-row cast-in-place pile and a double-row pile connecting beam connecting the two, a water-stop system is provided in the gap between the outer wall of the front-row cast-in-place pile and the rear-row cast-in-place pile and the soft soil, the water-stop system is a high-pressure rotary jet pile, the deformation control embedded area is arranged on the inner side of the double-row pile system, the deformation control embedded area is composed of the bite high-pressure rotary jet pile at the step, the surrounding cast-in-place pile and the anchor cable, wherein the surrounding cast-in-place pile and the bite high-pressure rotary jet pile are bite-connected in the transverse and longitudinal directions, and the bottom enters the bedrock, the anchor section of the anchor cable is arranged in the bedrock, the drainage structure backfill area is arranged in the space between the basement and the surrounding cast-in-place pile, and the drainage structure backfill area is composed of drainage gravel, drainage pipes and backfill fluidized solidified soil.

[0006] Preferably, the bottom of the high-pressure jet grouting piles penetrates the bedrock surface by not less than 0.5 meters, the rear row of cast-in-place piles penetrates below the bedrock surface, and the bottom of the front row of cast-in-place piles is not higher than the bedrock surface.

[0007] Preferably, the interlocking high-pressure jet grouting piles are constructed by pre-drilling holes on the ground before excavation of the foundation pit, and the strength of the pile body is not less than 0.8 MPa when excavated to the step elevation.

[0008] Preferably, the anchor cables are constructed in layers when the foundation pit is excavated to the anchor cable elevation, and after the anchor cable strength reaches the design requirement, earth excavation continues and the next anchor cable is constructed.

[0009] Preferably, the drainage structure backfill area is backfilled in layers when the basement is constructed to the steps. First, drainage gravel is set and drainage pipes are buried, and then backfill fluidized solidified soil is set. When the backfill fluidized solidified soil is solidified and the strength is not less than 0.5MPa, the basement above the step elevation is continued to be constructed.

[0010] Preferably, the top ends of the rear row cast-in-place piles and the front row cast-in-place piles are at a height above the existing ground.

[0011] Preferably, the high-pressure rotary jet pile includes a drill rod, a nozzle and a grouting pipe. The high-pressure rotary jet pile uses a drilling rig to drill a grouting pipe with a nozzle to a predetermined position in the soil layer. The nozzle is used to spray out high-pressure slurry or water. The grouting pipe is used to transport slurry or water. The grouting pipe is connected to a slurry preparation system and a nozzle. During the construction of the high-pressure rotary jet pile, the grouting pipe transports the pre-prepared slurry to the nozzle through a high-pressure generating device.

[0012] Preferably, the retaining cast-in-place pile includes a pile body and a steel frame. The steel frame is arranged inside the pile body to enhance the bearing capacity and bending resistance of the pile body. The steel frame consists of main bars and stirrups. The main bars are arranged along the length of the pile body, and the stirrups are arranged around the main bars to form a mesh structure. A concrete protective layer of a certain thickness is provided on the outside of the pile body to protect the steel frame from erosion by the external environment.

[0013] Compared with the prior art, the utility model has the following beneficial effects:

[0014] In this high-rigidity foundation pit support structure suitable for deep soft soil conditions, the water-stopping system combining a double-row pile system with high-pressure rotary jet piles is adopted to effectively control the soil and water loss around the foundation pit and ensure the stability during the foundation pit excavation process. Secondly, the setting of the deformation control embedded zone, using the combined effect of the interlocking high-pressure rotary jet piles, the surrounding cast-in-place piles and the anchor cables, greatly enhances the overall stiffness and deformation resistance of the support structure, and effectively reduces the impact of the foundation pit excavation on the surrounding environment. In addition, the setting of the drainage structure backfill area, through the reasonable arrangement of drainage gravel, drainage pipes and backfill fluidized solidified soil, realizes effective drainage and anti-floating during the basement construction, further ensuring the safety and efficiency of the foundation pit construction. In summary, the support structure provided by this technology has significant technical advantages under deep soft soil conditions, and provides an efficient and safe solution for foundation pit construction in urban renewal construction. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the overall structure of the utility model;

[0016] Figure 2 For this utility model Figure 1 Schematic diagram of the cross section of AA.

[0017] The meaning of each number in the figure is:

[0018] 1. Basement; 2. Adjacent buildings; 3. Existing ground; 4. Building pile foundation; 5. Groundwater level; 6. Soft soil; 7. Bedrock surface; 8. Bedrock; 9. Double-row pile connecting beam; 10. Rear row cast-in-place piles; 11. Front row cast-in-place piles; 12. High-pressure rotary jet piles; 13. Interlocking high-pressure rotary jet piles; 14. Enclosure cast-in-place piles; 15. Anchor cables; 16. Drainage pipes; 17. Drainage gravel; 18. Backfill with fluidized solidified soil. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0020] The utility model provides a high-rigidity foundation pit support structure suitable for deep soft soil conditions, such as Figure 1-Figure 2 As shown, it includes a double-row pile system, a deformation control embedded area and a drainage structure backfill area. The double-row pile system is composed of a front-row cast-in-place pile 11, a rear-row cast-in-place pile 10 and a double-row pile connecting beam 9 connecting the two. A water-stop system is provided in the gap between the outer wall of the front-row cast-in-place pile 11 and the rear-row cast-in-place pile 10 and the soft soil 6. The water-stop system is a high-pressure rotary jet pile 12. The deformation control embedded area is arranged on the inner side of the double-row pile system. The deformation control embedded area is composed of the interlocking high-pressure rotary jet pile 13 at the step, the surrounding cast-in-place pile 14 and the anchor cable 15. The surrounding cast-in-place pile 14 and the interlocking high-pressure rotary jet pile 13 are interlocked and connected in the horizontal and vertical directions, and the bottom enters the bedrock. The anchor section of the anchor cable 15 is arranged in the bedrock 8. The drainage structure backfill area is arranged in the space between the basement 1 and the surrounding cast-in-place pile 14. The drainage structure backfill area is composed of drainage gravel 17, a drainage pipe 16 and backfill fluidized solidified soil 18.

[0021] In this embodiment, the bottom of the high-pressure rotary jet pile 12 penetrates the bedrock surface 7 by no less than 0.5 meters, ensuring a firm bond between the high-pressure rotary jet pile 12 and the bedrock 8. This penetration enhances the bearing capacity of the high-pressure rotary jet pile 12, enabling it to effectively transfer and disperse the load from the upper structure, thereby improving the stability of the entire support structure. The rear row of cast-in-place piles 10 penetrates below the bedrock surface 7 of the bedrock 8, further enhancing the stability and bearing capacity of the support structure. Since the rear row of cast-in-place piles 10 penetrates deep into the bedrock 8, they can better resist the lateral soil pressure and water pressure, reducing the possibility of deformation and displacement of the foundation pit. The bottom of the front row of cast-in-place piles 11 is not higher than the bedrock surface 7 of the bedrock 8, ensuring good contact between the front row of cast-in-place piles 11 and the bedrock 8. This design enables the front row of cast-in-place piles 11 to effectively transfer the load to the bedrock 8, avoiding excessive concentration of load in the soil layer, thereby reducing the bending moment and deformation of the pile body.

[0022] Specifically, the interlocking high-pressure jet grouting piles 13 are constructed by pre-drilling holes on the ground before excavation of the foundation pit, and the strength of the pile body is not less than 0.8 MPa when excavated to the step elevation.

[0023] Furthermore, the anchor cables 15 are constructed in layers when the foundation pit is excavated to the elevation of the anchor cables 15. After the strength of the anchor cables 15 reaches the design requirements, the earthwork is continued to be excavated and the next anchor cable 15 is constructed. By constructing the anchor cables 15 in layers, the stability of the support structure can be gradually enhanced during the foundation pit excavation process. The construction of each layer of anchor cables 15 is carried out after the previous layer of anchor cables reaches the strength required by the design, which can ensure that the support structure always maintains sufficient rigidity and stability during the excavation process and effectively control the deformation of the foundation pit.

[0024] Furthermore, the drainage structure backfill area is backfilled in layers when the basement 1 is constructed to the steps. First, drainage gravel 17 is set and the drainage pipe 16 is buried, and then the backfill fluidized solidified soil 18 is set. When the backfill fluidized solidified soil 18 is solidified and the strength is not less than 0.5MPa, the construction of the basement 1 above the step elevation is continued.

[0025] Furthermore, the heights of the top ends of the rear row of cast-in-place piles 10 and the front row of cast-in-place piles 11 and the existing ground 3 .

[0026] Furthermore, the high-pressure rotary jet pile 12 includes a drill rod, a nozzle and a grouting pipe. The high-pressure rotary jet pile uses a drilling rig to drill a grouting pipe with a nozzle to a predetermined position in the soil layer. The nozzle is used to spray out high-pressure slurry or water. The grouting pipe is used to transport slurry or water. The grouting pipe is connected to a slurry preparation system and a nozzle. During the construction of the high-pressure rotary jet pile, the grouting pipe transports the pre-prepared slurry to the nozzle through a high-pressure generating device.

[0027] Furthermore, the retaining cast-in-place pile 14 includes a pile body and a steel frame. The steel frame is arranged inside the pile body to enhance the bearing capacity and bending resistance of the pile body. The steel frame is composed of main bars and stirrups. The main bars are arranged along the length direction of the pile body, and the stirrups are arranged around the main bars to form a mesh structure. A concrete protective layer of a certain thickness is provided on the outside of the pile body to protect the steel frame from erosion by the external environment.

[0028] When the high-rigidity foundation pit support structure of the utility model is used in deep soft soil conditions, if the proposed basement 1 is located in a soft soil 6 stratum, the groundwater level 5 is shallow, and there are adjacent buildings 2 and the building pile foundations 4 thereunder, the working principle of the support structure is as follows: First, a preliminary retaining structure is formed by constructing the front row of cast-in-place piles 11 and the rear row of cast-in-place piles 10 at the elevation of the existing ground 3. Subsequently, when the cast-in-place piles have a certain strength, high-pressure rotary jet piles 12 are constructed to engage with the front row of cast-in-place piles 11 and the rear row of cast-in-place piles 10 to form a continuous water-stop curtain, effectively blocking groundwater from infiltrating the foundation pit. The depth of the rear row of cast-in-place piles 10 penetrating into the bedrock 8 is greater than that of the front row of cast-in-place piles 11 to enhance the overall stability.

[0029] Next, double-row pile connecting beams 9 are constructed to connect the front and rear rows of cast-in-place piles to form a rigid double-row pile water-stopping and retaining structure, thereby further improving the stability of the foundation pit.

[0030] At the existing ground elevation, retaining cast-in-place piles 14 are constructed, and then the interlocking high-pressure jet grouting piles 13 are constructed by pre-drilling to form a deformation-controlled embedded area. This area utilizes the combined effects of the retaining cast-in-place piles 14, the interlocking high-pressure jet grouting piles 13 and the anchor cables 15 to effectively transmit and diffuse the soil pressure at the bottom of the double-row piles, thereby controlling the deformation of the foundation pit.

[0031] At the same time, the interlocking high-pressure jet-jet piles 13 also form a composite foundation, which improves the bearing capacity of the foundation soil at the step and provides good foundation conditions for the basement.

[0032] During the earth excavation process, the excavation time is strictly controlled to ensure that the strength of the interlocking high-pressure jet grouting piles 13 reaches the required level. At the same time, the excavation is carried out in layers and the anchor cables 15 are constructed in layers, and the deformation of the foundation pit is further controlled by the prestressing effect of the anchor cables.

[0033] Finally, when the proposed basement 1 is constructed to the step, the space between the proposed basement and the retaining piles is backfilled with a drainage structure. By backfilling drainage gravel 17, burying drainage pipes 16 and backfilling fluidized solidified soil 18, an effective drainage system is formed to prevent groundwater from affecting the basement construction and ensure the stability and bearing capacity of the backfill soil.

[0034] The above shows and describes the basic principle, main features and advantages of the utility model. Those skilled in the art should understand that the utility model is not limited by the above embodiments. The above embodiments and descriptions are only preferred examples of the utility model and are not used to limit the utility model. Without departing from the spirit and scope of the utility model, the utility model may have various changes and improvements, which fall within the scope of the utility model to be protected. The scope of protection of the utility model is defined by the attached claims and their equivalents.

Claims

1. A high-rigidity foundation pit support structure suitable for deep soft soil conditions, comprising a double-row pile system, a deformation control embedding area and a drainage structure backfill area, characterized in that: The double-row pile system is composed of a front-row cast-in-place pile (11), a rear-row cast-in-place pile (10) and a double-row pile connecting beam (9) connecting the two. A water-stopping system is provided in the gap between the outer wall of the front-row cast-in-place pile (11) and the rear-row cast-in-place pile (10) and the soft soil (6). The water-stopping system is a high-pressure rotary jet pile (12). A deformation control embedded area is arranged on the inner side of the double-row pile system. The deformation control embedded area is composed of a bite-engaged high-pressure rotary jet pile (13) at a step, a surrounding cast-in-place pile (14) and an anchor cable (15). The surrounding cast-in-place pile (14) and the bite-engaged high-pressure rotary jet pile (13) are bite-engaged in the transverse direction and the longitudinal direction, and the bottom enters the bedrock. The anchoring section of the anchor cable (15) is arranged in the bedrock (8). The drainage structure backfill area is arranged in the space between the basement (1) and the surrounding cast-in-place pile (14). The drainage structure backfill area is composed of drainage gravel (17), a drainage pipe (16) and backfilled fluidized solidified soil (18).

2. The high-rigidity foundation pit support structure suitable for deep soft soil conditions according to claim 1 is characterized in that: The bottom of the high-pressure jet grouting pile (12) penetrates the bedrock surface (7) by no less than 0.5 meters, the rear row of cast-in-place piles (10) penetrates below the bedrock surface (7) of the bedrock (8), and the bottom of the front row of cast-in-place piles (11) is not higher than the bedrock surface (7) of the bedrock (8).

3. The high-rigidity foundation pit support structure suitable for deep soft soil conditions according to claim 1 is characterized in that: The interlocking high-pressure jet grouting pile (13) is constructed by pre-drilling holes on the ground before excavating the foundation pit, and the pile body strength is not less than 0.8 MPa when excavated to the step elevation.

4. The high-rigidity foundation pit support structure suitable for deep soft soil conditions according to claim 1 is characterized in that: The anchor cables (15) are constructed in layers when the foundation pit is excavated to the elevation of the anchor cables (15). After the strength of the anchor cables (15) reaches the design requirements, earthwork is continued to be excavated and the next anchor cable (15) is constructed.

5. The high-rigidity foundation pit support structure suitable for deep soft soil conditions according to claim 1 is characterized in that: The drainage structure backfill area is backfilled in layers when the basement (1) is constructed to the step. First, drainage gravel (17) is set and the drainage pipe (16) is buried. Then, backfill fluidized solidified soil (18) is set. When the backfill fluidized solidified soil (18) is solidified and has a strength of not less than 0.5 MPa, the basement (1) above the step elevation is continued to be constructed.

6. The high-rigidity foundation pit support structure suitable for deep soft soil conditions according to claim 1 is characterized in that: The heights of the tops of the rear row cast-in-place piles (10) and the front row cast-in-place piles (11) and the existing ground surface (3).

7. The high-rigidity foundation pit support structure suitable for deep soft soil conditions according to claim 1 is characterized in that: The high-pressure jet grouting pile (12) comprises a drill rod, a nozzle and a grouting pipe. The high-pressure jet grouting pile uses a drilling rig to drill a grouting pipe with a nozzle to a predetermined position in the soil layer. The nozzle is used to spray out high-pressure slurry or water, and the grouting pipe is used to transport the slurry or water.

8. The high-rigidity foundation pit support structure suitable for deep soft soil conditions according to claim 1 is characterized in that: The retaining cast-in-place pile (14) comprises a pile body and a steel frame, wherein the steel frame is arranged inside the pile body and consists of main bars and stirrups, wherein the main bars are arranged along the length direction of the pile body and the stirrups are arranged around the main bars to form a mesh structure, and a concrete protective layer of a certain thickness is arranged outside the pile body.

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