Soil-rock composite stratum deep foundation pit supporting structure and construction method thereof

Abstract

The invention belongs to the technical field of foundation pit construction, and particularly relates to a soil-rock composite stratum deep foundation pit supporting structure which comprises supporting plates, the supporting plates which are located on different planes and are in butt joint with each other are fixed through inter-plate connecting pieces, a supporting system is installed on the soil back face of each supporting plate, and the supporting systems and a supporting frame are installed and fixed. The other assembled supporting frames can penetrate through the supporting frame installed on the inner side of the deep foundation pit, a traditional supporting structure and a traditional construction mode are abandoned, firstly, the supporting plate is installed, then the supporting system is fixed to the supporting plate, the supporting plate is connected with the supporting frames through the supporting system, and therefore the supporting plate is supported and fixed, and the supporting effect is achieved. After the supporting frame is installed, the central area of the supporting frame has a large passing space, the supporting frame to be used can be assembled on the ground, and then the assembled supporting frame penetrates through the installed supporting frame in a vertical hoisting mode.

Description

Technical Field

[0001] This invention belongs to the field of foundation pit construction technology, specifically relating to a deep foundation pit support structure and its construction method in soil-rock composite strata. Background Technology

[0002] Compared to single strata dominated by soil, soil-rock composite strata present greater challenges in excavation due to their complex geological structure. Excavation equipment, when operating only on the surface, struggles to effectively handle the high strength and complex structure of the rock in soil-rock composite strata, resulting in low excavation efficiency. To improve operational efficiency, for deep foundation pit projects, excavation equipment is typically placed directly inside the pit to carry out operations. During the excavation process, the excavated soil needs to be transported to the surface using hoisting equipment.

[0003] After the foundation pit is excavated to a certain depth, the pressure exerted by the soil and rock on the sidewalls gradually increases. At this point, it is necessary to carry out sidewall support work in a timely manner. The traditional method is to install appropriate support structures, such as piles, underground continuous walls, or internal support systems, to balance the pressure on the sidewalls and ensure the stability of the foundation pit. Only after the support work is completed can the excavation continue downward. As the excavation depth increases, when the next set depth node is reached, the excavation is paused again, and the above support work process is repeated. This cycle is repeated, alternating between excavation and support, until the designed foundation pit depth is reached.

[0004] For large deep foundation pits, traditional support structures and construction methods can handle the task well. However, for small deep foundation pits that can just accommodate one excavation machine, assembling or installing traditional support structures in the deep foundation pit is very laborious, and may even be impossible to complete due to limited space.

[0005] Taking traditional frame support structures as an example, these structures usually need to be assembled on-site in the pit. In small-area deep foundation pits, the limited space makes assembly work extremely difficult, and sometimes installation cannot be completed at all due to insufficient space. In terms of installation time, in small-area deep foundation pits, due to the limited operating space, the installation time will be longer for the same unit installation area compared to large-area foundation pits. In terms of cost, using traditional support structures in small-area deep foundation pits not only increases labor costs due to the increased difficulty of operation, but may also lead to increased material loss due to the inability to install smoothly, resulting in a higher total cost compared to large-area foundation pits. Summary of the Invention

[0006] To address the problems mentioned in the background section, this invention provides a deep foundation pit support structure and its construction method in soil-rock composite strata. When the area of ​​the deep foundation pit is small, the support structure can be assembled on the ground, and the assembled support structure can directly pass through the already installed support structure.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a deep foundation pit support structure for soil-rock composite strata, comprising support plates, wherein the support plates located at different planes are fixed to each other by inter-plate connectors, and a support system is installed on the back soil surface of the support plates, and the support system is installed and fixed to the support frame.

[0008] The assembled support frames can pass through the support frames installed inside the deep foundation pit.

[0009] As a preferred embodiment of the deep foundation pit support structure for soil-rock composite strata of the present invention, the support frame includes a rectangular frame structure composed of a middle connecting frame, a side connecting frame, and a corner connecting frame. Both ends of the middle connecting frame are connected to a number of straight structures formed by sequentially connected side connecting frames. Adjacent straight structures are connected by corner connecting frames. The joints of the middle connecting frame, side connecting frame, and corner connecting frame are fixedly connected by combined connectors. Telescopic support rods are rotatably connected between the middle connecting frames of adjacent straight structures.

[0010] As a preferred embodiment of the deep foundation pit support structure in the soil-rock composite strata of the present invention, two oppositely arranged intermediate connecting frames are provided with outwardly extended portions protruding towards the support plate, and the distance between the two outwardly extended portions is greater than the maximum distance between the two oppositely arranged frame connecting frames.

[0011] As a preferred embodiment of the deep foundation pit support structure for soil-rock composite strata of the present invention, the minimum accommodating width of the outer expansion portion is greater than the thickness of the support frame.

[0012] As a preferred embodiment of the deep foundation pit support structure for soil-rock composite strata of the present invention, a rotating bracket is fixedly connected to the bottom surface of the intermediate connecting frame and the frame connecting frame, and a sleeve is rotatably connected to one end of the rotating bracket, with a bolt threaded to the inner side of one end of the sleeve.

[0013] As a preferred embodiment of the deep foundation pit support structure for soil-rock composite strata of the present invention, a limiting seat is fixedly connected to the top of the rotating bracket.

[0014] As a preferred embodiment of the deep foundation pit support structure in the soil-rock composite strata of the present invention, the support system includes a pressure plate, an extrusion rod, and a mating rod. The pressure plate is used to fix to the surface of the support plate. One end of the pressure plate is rotatably connected to one end of the extrusion rod, and the other end of the extrusion rod is fixedly connected to the mating rod. One end of the mating rod is provided with several mating holes for bolt engagement.

[0015] As a preferred embodiment of the deep foundation pit support structure in the soil-rock composite strata of the present invention, the compression rod has a length adjustment function.

[0016] As a preferred embodiment of the deep foundation pit support structure for soil-rock composite strata of the present invention, the mating hole is a through hole or a threaded hole.

[0017] A construction method for a deep foundation pit support structure in soil-rock composite strata includes the following steps:

[0018] S1: Deep foundation pit excavation operation at the target location;

[0019] S2: Assemble a support frame with the appropriate size on the ground according to the area of ​​the deep foundation pit;

[0020] S3: Within the safe excavation depth of the deep foundation pit, install and initially fix the support plate;

[0021] S4: Install the support system on the support plate;

[0022] S5: Hoist the assembled support frame into the deep foundation pit and insert the mating rod into the inside of the sleeve. After the relative position of the sleeve and the mating rod is determined, lock the relative position between the sleeve and the mating rod.

[0023] S6: Adjust the length of the extrusion rod as needed;

[0024] S7: Add counterweights to the support frame as needed;

[0025] S8: After the support plate is fixed, continue to excavate the deep foundation pit downwards;

[0026] S9: Repeat the above steps until the depth of the deep foundation pit reaches the target depth.

[0027] Compared with the prior art, the beneficial effects of the present invention are: it abandons the traditional support structure and construction method, firstly installs the support plate, and then fixes the support system on the support plate, that is, fixes the pressure plate to the support plate. The rectangular support frame serves as the main force-bearing body, and the support plate is connected to the support frame through the support system, thereby achieving the support plate being supported and fixed. After the support frame is installed, its central area has a large passage space, which allows the support frame to be used to be assembled on the ground. Then, the assembled support frame is vertically hoisted through the already installed support frame. Attached Figure Description

[0028] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0029] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0030] Figure 2 This is a top view of the supporting frame structure in this invention;

[0031] Figure 3This is a schematic diagram of the connection structure of the support system in this invention;

[0032] Figure 4 This is a cross-sectional view of the semi-fixed bolt structure in this invention;

[0033] Figure 5 This is a cross-sectional view of the structure in this invention where the bolts are completely through.

[0034] Figure 6 This is a top view of the overall structure of the present invention;

[0035] Figure 7 This is a schematic diagram of the inter-plate connector in the present invention;

[0036] In the picture:

[0037] 1. Support plate; 2. Inter-plate connectors; 3. Support frame; 4. Support system;

[0038] 301. Intermediate connecting frame; 302. Outer expansion section; 303. Frame connecting frame; 304. Corner connecting frame; 305. Combined connecting piece; 306. Telescopic support rod; 307. Rotating bracket; 308. Limiting seat; 309. Sleeve; 3010. Bolt;

[0039] 401. Pressure plate; 402. Extrusion rod; 403. Fitting rod; 404. Fitting hole. Detailed Implementation

[0040] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] like Figures 1-7 As shown:

[0042] A deep foundation pit support structure for soil-rock composite strata includes a support plate 1. The support plates 1 located at different planes are connected to each other by inter-plate connectors 2. A support system 4 is installed on the back soil surface of the support plate 1. The support system 4 is installed and fixed to the support frame 3.

[0043] The assembled other support frames 3 can pass through the support frames 3 installed inside the deep foundation pit.

[0044] In this embodiment, compared with a single stratum mainly composed of soil, the soil-rock composite stratum is more difficult to excavate due to the complexity of its geological structure. When the excavation equipment is only excavated on the ground, it is difficult to effectively deal with the high strength and complex structure of the rock in the soil-rock composite stratum, resulting in low excavation efficiency. In order to improve the efficiency of operation, for deep foundation pit projects, the excavation equipment is usually placed directly inside the foundation pit to carry out the operation. During the excavation process, the excavated soil needs to be transported to the ground with the help of hoisting equipment.

[0045] After the foundation pit is excavated to a certain depth, the pressure exerted by the soil and rock on the sidewalls gradually increases. At this time, it is necessary to carry out sidewall support work in a timely manner. The traditional method is to install appropriate support structures, such as piles, underground continuous walls, or internal support systems, to balance the pressure on the sidewalls and ensure the stability of the foundation pit. Only after the support work is completed can the excavation continue downward. As the excavation depth increases, when the next set depth node is reached, the excavation is paused again, and the above support work process is repeated. This cycle is repeated, alternating between excavation and support, until the designed foundation pit depth is reached.

[0046] For large deep foundation pits, traditional support structures and construction methods can handle the task well. However, for small deep foundation pits that can just accommodate one excavation machine, assembling or installing traditional support structures in the deep foundation pit is very laborious, and may even be impossible to complete due to limited space.

[0047] To solve the above problems, this invention abandons the traditional support structure and construction method. First, the support plate 1 is installed, and then the support system 4 is fixed to the support plate 1, that is, the pressure plate 401 is fixed to the support plate 1. A rectangular support frame 3 serves as the main load-bearing structure. The support plate 1 is connected to the support frame 3 through the support system 4, thereby achieving the support and fixation of the support plate 1. After installation, the support frame 3 has a large central area with ample space for passage, allowing the support frame 3 to be assembled on the ground. Figure 1As shown, the assembled support frame 3 is then vertically hoisted through the already installed support frame 3. After the support frame 3 is hoisted to the target position, it is adjusted to a horizontal state. Then, the angle of the mating rod 403 is manually adjusted so that the mating rod 403 can be inserted into the sleeve 309 as the support frame 3 continues to move downward. After the mating rod 403 is inserted into the sleeve 309, when the support frame 3 descends to a suitable height, the relative position between the mating rod 403 and the sleeve 309 is fixed. Then, the support frame 3 continues to move downward, and the pressing rod 402 will get closer and closer to a horizontal state. During this process, as the support frame 3 descends, the pressing force of the pressure plate 401 on the support plate 1 will increase, so that the support plate 1 will obtain sufficient support force. That is to say, when the support plate 1 is fixed by the support system 4, the support system 4 is in a horizontal state or tilted upward.

[0048] Since the support plate 1 is generally made of a material that can be attracted by a magnet, such as iron, the pressure plate 401 and the support plate 1 can be fixed by magnetic force. Since the fixation between the pressure plate 401 and the support plate 1 is only a preliminary fixation to facilitate the docking of the connecting rod 403 and the sleeve 309, the pressure plate 401 does not need to have a large fixing force during the preliminary fixation.

[0049] It should be noted that the interplate connector 2 can increase the connection strength between the two support plates 1, but the use of the interplate connector 2 is not a necessary condition.

[0050] In an optional embodiment, the support frame 3 includes a rectangular frame structure composed of an intermediate connecting frame 301, a side frame connecting frame 303, and a corner connecting frame 304. Both ends of the intermediate connecting frame 301 are connected to a number of sequentially connected side frame connecting frames 303 forming a straight structure. Adjacent straight structures are connected by a corner connecting frame 304. The interlocking points of the intermediate connecting frame 301, the side frame connecting frame 303, and the corner connecting frame 304 are fixedly connected by a combined connector 305. A telescopic support rod 306 is rotatably connected between the intermediate connecting frames 301 in two adjacent straight structures.

[0051] In this embodiment, when assembling the support frame 3, the appropriate size of the support frame 3 is selected according to the area of ​​the deep foundation pit. The support frame 3 needs to be able to be placed in the deep foundation pit, and the support frame 3 needs to have a certain distance from the pit wall. The two ends of the intermediate connecting frame 301 are connected and fixed to the side frame connecting frame 303 through the combined connecting piece 305. If multiple side frame connecting frames 303 need to be connected to each other, they are also connected to each other through the combined connecting piece 305. The structural strength of the support frame 3 can be increased by the telescopic support rod 306. The telescopic support rod 306 can be adjusted in length and locked at that length.

[0052] In an optional embodiment, two opposing intermediate connecting frames 301 are provided with outwardly protruding portions 302 (e.g., ...) protruding towards the support plate 1. Figure 2 As shown, the outer expansion portion 302 refers to the protruding structure of the intermediate connecting frame 301 extending towards the support plate 1 (used to expand the space through which the frame passes). The distance between the two outer expansion portions 302 is greater than the maximum distance between the two oppositely arranged frame connecting frames 303, and the minimum accommodating width of the outer expansion portion 302 is greater than the thickness of the support frame 3.

[0053] In this embodiment, when the support frame 3 is square, the assembled support frame 3 can pass through the support frame 3 installed inside the deep foundation pit through the provided expansion part 302.

[0054] In an optional embodiment, a rotating bracket 307 is fixedly connected to the bottom surface of the intermediate connecting bracket 301 and the frame connecting bracket 303 (e.g., ...). Figure 3 As shown, the rotating bracket 307 is a structure that supports the rotating sleeve 309. One end of the rotating bracket 307 is rotatably connected to the sleeve 309, and one end of the sleeve 309 is threaded with a bolt 3010. The top end of the rotating bracket 307 is fixedly connected to a limiting seat 308.

[0055] In this embodiment, the connection between the mating rod 403 and the support frame 3 is achieved through the sleeve 309. After the mating rod 403 is inserted into the sleeve 309 to a suitable length, the position between the sleeve 309 and the mating rod 403 is locked by the bolt 3010. The rotation range of the sleeve 309 can be limited by the set limit seat 308. When the mating rod 403 is inserted into the inside of the sleeve 309, the mating rod 403 can only be in a horizontal state or tilted upward.

[0056] In an optional embodiment, the support system 4 includes a pressure plate 401, a pressing rod 402, and a mating rod 403. The pressure plate 401 is used to fix to the surface of the support plate 1. One end of the pressure plate 401 is rotatably connected to one end of the pressing rod 402. The other end of the pressing rod 402 is fixedly connected to the mating rod 403. One end of the mating rod 403 is provided with a plurality of mating holes 404 that mate with bolts 3010.

[0057] In this embodiment, when the compression rod 402 itself does not have the function of adjusting the length, this method is preferentially used under the premise that the foundation pit wall surface is regular, such as... Figure 1As shown, when the support plate 1 is fixed by the support system 4 and the support system 4 is tilted upwards, the weight of the support frame 3 itself can compress the mating rod 403. This compression is achieved through the weight of the support frame 3 itself. Even when the compression rod 402 does not have a length adjustment function, it is not necessary to precisely control the fixed position of the mating rod 403 and the sleeve 309 based on the distance between the pressure plate 401 and the rotating bracket 307, greatly reducing the installation difficulty. Furthermore, counterweights can be applied to the support frame 3 as needed. After installation, continued excavation of the deep foundation pit may disrupt the previous soil stress distribution, causing the support plate 1 to tilt towards the support. The support frame 3 tends to move closer to or further away from the support frame 3. When the support plate 1 tends to move away from the support frame 3, the support frame 3 moves downward due to its own weight, thereby automatically adjusting the position of the pressure plate 401 relative to the support frame 3 to obtain a continuous and stable squeezing effect. When the support plate 1 tends to move closer to the support frame 3, the support frame 3 will be forced to rise due to the squeezing force. Regardless of the direction of the movement of the support plate 1, the stress of the pit wall of the deep foundation pit can be reflected in a timely manner through the position change of the support frame 3. This not only ensures the safety of the support but also provides early warning, allowing workers to take appropriate measures in advance based on the actual situation.

[0058] The extrusion rod 402 has a length adjustment function (the extrusion rod 402 can be a threaded adjustment extrusion rod, a hydraulic locking telescopic rod, or an electric push rod with an integrated self-locking function). When the extrusion rod 402 itself has the function of adjusting the length and locking at that length, it is suitable for uneven and irregular foundation pit walls. After the mating rod 403 is fixed in place with the sleeve 309, the length can be finely adjusted by the extrusion rod 402, resulting in better performance. Of course, the extrusion rod 402 having a length adjustment function does not conflict with the implementation method where the extrusion rod 402 does not have a length adjustment function.

[0059] In an optional embodiment, the mating hole 404 is a through hole or a threaded hole.

[0060] In this embodiment: as follows Figure 4 and Figure 5 As shown, bolt 3010 can be threaded to one side of sleeve 309, or it can pass through sleeve 309 and be threaded to sleeve 309.

[0061] A construction method for a deep foundation pit support structure in soil-rock composite strata includes the following steps:

[0062] S1: Deep foundation pit excavation operation at the target location;

[0063] S2: Assemble a support frame 3 with the appropriate size on the ground according to the area of ​​the deep foundation pit;

[0064] S3: Within the safe excavation depth of the deep foundation pit, install and initially fix the support plate 1;

[0065] S4: Install the support system 4 on the support plate 1;

[0066] S5: Hoist the assembled support frame 3 into the deep foundation pit, and insert the mating rod 403 into the inside of the sleeve 309. After the relative position of the sleeve 309 and the mating rod 403 is determined, lock the relative position between the sleeve 309 and the mating rod 403.

[0067] S6: Adjust the length of the extrusion rod 402 as needed;

[0068] S7: Add counterweight to support frame 3 as needed;

[0069] S8: After the support plate 1 is fixed, continue to excavate the deep foundation pit downwards;

[0070] S9: Repeat the above steps until the depth of the deep foundation pit reaches the target depth.

[0071] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A deep foundation pit support structure in a soil-rock composite stratum, comprising a support plate (1), characterized in that: The supporting plates (1) that are connected to each other at different planes are fixed by inter-plate connectors (2); a supporting system (4) is installed on the back-to-soil surface of the supporting plates (1); and the supporting system (4) is installed and fixed to the supporting frame (3); The other assembled support frames (3) can pass through the support frame (3) installed inside the deep foundation pit.

2. The soil-rock composite stratum deep foundation pit support structure according to claim 1 is characterized by: The support frame (3) comprises a rectangular frame structure composed of an intermediate connecting frame (301), a frame connecting frame (303) and a corner connecting frame (304); both ends of the intermediate connecting frame (301) are connected to a linear structure formed by a plurality of frame connecting frames (303) connected in sequence; two adjacent linear structures are connected via a corner connecting frame (304); the intermediate connecting frame (301), the frame connecting frame (303) and the corner connecting frame (304) are fixedly connected at their joints via a combined connecting piece (305); and a telescopic supporting rod (306) is rotatably connected between the intermediate connecting frames (301) in the two adjacent linear structures.

3. The soil-rock composite stratum deep foundation pit support structure according to claim 2 is characterized by: Two oppositely arranged middle connecting frames (301) are provided with outwardly extending portions (302) protruding in the direction of the supporting plate (1), and the distance between the two outwardly extending portions (302) is greater than the maximum distance between two oppositely arranged frame connecting frames (303).

4. The soil-rock composite stratum deep foundation pit support structure according to claim 3 is characterized by: The minimum accommodation width of the outwardly expanded portion (302) is greater than the thickness of the supporting frame (3).

5. The soil-rock composite stratum deep foundation pit support structure according to claim 2, 3 or 4, characterized in that: A rotating bracket (307) is fixedly connected to the bottom surfaces of the middle connecting frame (301) and the frame connecting frame (303), one end of the rotating bracket (307) is rotatably connected to a sleeve (309), and one end of the sleeve (309) is threadedly connected to a bolt (3010) on the inner side.

6. The soil-rock composite stratum deep foundation pit support structure according to claim 5 is characterized by: The top end of the rotating bracket (307) is fixedly connected to a limiting seat (308).

7. The soil-rock composite stratum deep foundation pit support structure according to claim 1 is characterized by: The support system (4) comprises a pressure plate (401), an extrusion rod (402) and a matching rod (403); the pressure plate (401) is used to be fixed to the surface of the support plate (1); one end of the pressure plate (401) is rotatably connected to one end of the extrusion rod (402); the other end of the extrusion rod (402) is fixedly connected to the matching rod (403); one end of the matching rod (403) is provided with a plurality of matching holes (404) that match the bolts (3010).

8. The soil-rock composite stratum deep foundation pit support structure according to claim 7 is characterized by: The squeezing rod (402) has a length adjustment function.

9. The soil-rock composite stratum deep foundation pit support structure according to claim 7 is characterized by: The matching hole (404) is a through hole or a threaded hole.

10. A soil-rock composite stratum deep foundation pit support structure and its construction method, comprising the soil-rock composite stratum deep foundation pit support structure according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1: deep foundation pit excavation at the target location; S2: Assemble a supporting frame (3) of appropriate size on the ground according to the area of ​​the deep foundation pit; S3: Install the support plate (1) within the safe excavation depth of the deep foundation pit and initially secure it; S4: Installing a support system (4) on the support plate (1); S5: hoisting the assembled support frame (3) into the deep foundation pit, and inserting the matching rod (403) into the inner side of the sleeve (309). After the relative position of the sleeve (309) and the matching rod (403) is determined, the relative position between the sleeve (309) and the matching rod (403) is locked; S6: Adjust the length of the extrusion rod (402) as needed; S7: Adding a counterweight to the supporting frame (3) as required; S8: After the support and fixation of the supporting plate (1) is completed, the deep foundation pit is excavated downwards; S9: Repeat the above steps until the depth of the deep foundation pit reaches the target depth.

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