A simple device for embedding lateral earth pressure cells in underground continuous walls and its usage method

Abstract

This invention discloses a simple device and method for embedding lateral earth pressure cells in diaphragm walls, relating to the application technology of measuring lateral earth pressure in diaphragm walls during deep foundation pit and other underground space engineering projects. The device consists of a rope, hook, frame, push rod, roller, earth pressure cell hanging bag, and spring. In use, the hook is first fixed to the horizontal reinforcement bars of the reinforcing cage, and then the earth pressure cell is placed into the hanging bag. After the reinforcing cage is lowered, the rope is pulled upwards, causing the frame and push rod to rotate and translate the earth pressure cell upwards clockwise. When the earth pressure cell contacts the soil layer, the rope is continued to be pulled upwards, causing the rear support rod of the earth pressure cell to push forward until the earth pressure cell is in full contact with the soil. Finally, the rope is tied to the top of the reinforcing cage. This simple device ensures full contact between the earth pressure cell and the soil, is low in cost, and easy to manufacture. It can be widely used in embedding lateral earth pressure cells of different sizes in diaphragm walls under complex construction conditions.

Description

Technical Field

[0001] This invention relates to a soil pressure cell installation technology for measuring lateral soil pressure on underground continuous walls in deep foundation pit and other underground space engineering projects, belonging to the field of engineering construction technology. Background Technology

[0002] With the continuous development of society and economy, my country's urbanization is further advancing, and infrastructure construction is booming. Due to the scarcity of urban land resources, the construction of high-rise buildings and the improvement of large-scale underground transportation facilities are particularly important to meet the needs of urban capacity. The smooth implementation of foundation pit excavation is the foundation for the construction of the aforementioned buildings and facilities. Foundation pit excavation requires the prior construction of a support structure before the soil in the pit is excavated. During the excavation process, the soil pressure will change, and the retaining structure will deform accordingly. The accuracy of soil pressure calculation is crucial for foundation pit design, and real-time monitoring of soil pressure during construction can also serve as the basis for implementing safety early warning and control measures. For the aforementioned high-rise buildings and large-scale underground transportation facilities, the corresponding foundation pits are often deep and irregularly shaped, and existing calculation theories are insufficient to accurately calculate the soil pressure of deep and irregularly shaped foundation pits. During construction, in order to clarify the soil pressure at the retaining structure, soil pressure cells are often pre-installed to monitor the soil pressure during the excavation process. However, the installation of soil pressure cells is often a challenge, the key being that the soil pressure cells can be accurately installed at the interface between the retaining structure and the soil to ensure the accuracy of the measurement results. Currently, there are several main methods for installing lateral earth pressure cells in diaphragm walls during deep foundation pit engineering, and each method also has its own problems:

[0003] (1) Drilling method

[0004] First, a guide frame is fabricated according to the diameter and depth of the required measurement hole. Then, the earth pressure gauges are fixed on the guide frame according to their respective installation points. Next, the guide frame is placed into the borehole. Finally, the hole is sealed by backfilling with fine sand or grouting. This method requires two drilling operations, which is costly. Drilling can cause soil arching, leading to underestimation of the measurement results. In addition, the drilling method cannot guarantee that the earth pressure cell is positioned precisely at the interface between the retaining structure and the soil.

[0005] (2) Hanging cloth method

[0006] A canvas sheet is made, and a bag for holding an earth pressure gauge is sewn onto it. The bag's position is determined by the depth of the measuring point. The canvas is tied to the outside of the retaining wall's reinforcing cage, and the earth pressure gauge is placed inside the bag. A wire is fixed to the canvas and led to the top of the retaining structure. The canvas containing the earth pressure gauge is then lowered into the trench along with the reinforcing cage. When concrete is poured, the canvas will be subjected to the lateral thrust of the flowing concrete, making it in close contact with the trench wall soil. However, when using this method, concrete often intrudes into the space between the canvas and the outer soil, causing the earth pressure gauge to be covered by concrete.

[0007] (3) Pneumatic pressure method

[0008] The earth pressure cells are fixed to pneumatic components and placed on a steel frame. Before concrete pouring, they are lowered into the trench, and pressure is applied to each pneumatic component to secure the earth pressure cells to the trench wall. After concrete pouring, the air pressure is released, allowing the earth pressure cells to fully contact the soil surface under the pressure of the concrete. This method is complex to operate, and the jacking force provided by the pneumatic components is limited.

[0009] (4) Horizontal propulsion method

[0010] Using a specially designed horizontal pushing device (see application publication number CN104863108A), the earth pressure box is fixed to a device tray at one end and to a reinforcing cage at the other. The device has an internal "V"-shaped structure connected to a rope; lifting the rope extends the V-shaped structure, causing the tray to extend laterally along the guide rod, thus bringing the earth pressure box into contact with the soil. Another patent document (CN113250174A) designs a device that uses pulling a pin inside a bracket to cause an internal spring to horizontally push the tray, thus pressing the earth pressure box against the soil. In summary, these devices are relatively complex to manufacture and have horizontal guide rods. If the guide rod is too long, it is prone to scraping against the reinforcing cage during lowering; if the guide rod is too short, its pushing stroke is also short, and it may not guarantee that the earth pressure box can be pushed to the outer soil wall. Therefore, the length of the guide rod must be customized according to the trench section size and the reinforcing cage size, resulting in limited adaptability. Even if the length is customized, the customized guide rod length may not meet the construction conditions due to the randomness of the construction process (i.e., the distance between the steel cage and the outside of the soil is related to the hoisting process and has a high degree of uncertainty). Summary of the Invention

[0011] To address the various problems existing in current diaphragm wall lateral earth pressure cell (PPC) installation technology, this invention designs a simple PPC installation device for diaphragm walls. This device is characterized by low cost, ease of use, simple operation, and good installation results, and is applicable to diaphragm walls of various widths. By applying this invention, the PPC can achieve full contact with the soil outside the diaphragm wall during installation, thereby ensuring a high success rate in installation and high measurement accuracy.

[0012] To achieve the above objectives, the present invention adopts the following technical solution:

[0013] A simple lateral earth pressure box embedding device for underground continuous wall is provided. The embedding device is installed on the steel cage in the foundation pit and is located between the steel cage and the soil outside the trench wall of the underground continuous wall.

[0014] The installation device includes ropes, hooks, poles, push rods, earth pressure boxes, hanging bags, and springs;

[0015] The rope is connected to the lower end of the pole frame, and the upper end of the pole frame is hinged to the hook, which is fixed to the transverse reinforcing bars of the reinforcing cage.

[0016] The earth pressure box hanging bag is hung at the lower end of the pole frame;

[0017] The upper end of the push rod is hinged to the rod frame. When the rod frame is raised, the soil pressure box hanging bag contacts the lower end of the push rod. A spring is also provided between the push rod and the rod frame.

[0018] The hook, rod frame, and push rod are all frame structures, each containing a pair of vertical rods and a horizontal rod. The pair of vertical rods are parallel to each other, and the horizontal rod is located between the lower ends of the pair of vertical rods.

[0019] The upper part of the vertical bar of the hook is the hook body, which is hung on the horizontal steel bars of the steel cage;

[0020] The upper end of the vertical rod of the pole frame is hinged to both ends of the horizontal rod of the hook, the rope is fixed to the horizontal rod of the pole frame, and the earth pressure box hanging bag is hung at the lower end of the two vertical rods of the pole frame;

[0021] As a further preferred option, the vertical rod of the push rod has an inverted "L" structure, with the upper end of the vertical rod of the push rod hinged to the lower middle position of the vertical rod of the rod holder, and one vertical rod of the push rod corresponds to one vertical rod of the rod holder.

[0022] As a further preferred option, the crossbar of the push rod is fitted with a roller to reduce the friction between the push rod and the soil pressure box bag.

[0023] A method for using a simple lateral earth pressure cell embedding device for underground continuous wall includes the following steps:

[0024] S1, fix the hook to the horizontal reinforcing bar of the steel cage;

[0025] S2. After the hook, rod, and push rod hang down naturally, place the earth pressure box in the earth pressure box hanging bag.

[0026] S3, the earth pressure box wire is led to the top of the steel cage during the lowering process. After the steel cage is lowered, the rope is lifted to make the pole rotate clockwise.

[0027] S4. When the earth pressure box hanging bag is completely pressed against the soil outside the trench wall, the rope can no longer be pulled up. At this time, the tensioned rope is tied to the horizontal bar at the top of the steel cage, and the concrete is poured.

[0028] As a further preferred option, the hooks can be fixed to the transverse reinforcing bars of the steel cage before or during the lowering of the steel cage, either by using binding straps or by welding.

[0029] As a further preferred option, in step S3, the tensioning of the rope is carried out in two steps:

[0030] S31, the earth pressure box hanging bag and push rod move with the frame. Since the connection between the earth pressure box hanging bag and the frame is flexible, the earth pressure box hanging bag is vertically downward during the rotation of the frame until the earth pressure box hanging bag comes into contact with the roller. As the frame continues to rotate clockwise, the bottom of the earth pressure box inside the earth pressure box hanging bag will be the first to contact the outer soil.

[0031] S32, continue to pull the rope up. As the pole rotates clockwise, the earth pressure box gets closer and closer to the outer soil until it is completely against the outer soil. The spring will stretch further and apply normal force through the roller to ensure that the earth pressure box is in close contact with the outer soil.

[0032] Beneficial effects:

[0033] Compared with existing technologies, the earth pressure box embedding equipment designed in this invention has fewer components, is simpler to manufacture, and has a relatively lower cost. The embedding process is quick and easy; the earth pressure box is fixed to the horizontal reinforcement of the steel cage via hooks, then hung in a hanging bag. As the steel cage is lowered, the earth pressure box is led to the top of the cage. Once the cage is lowered, the rope is pulled to the maximum height, and finally, the rope is tied to the end of the cage, eliminating the drilling process of the drilling method and the pressurization process of the pneumatic method. The embedding effect is good; compared with the hanging cloth method, it ensures full contact between the earth pressure box and the soil, effectively preventing concrete from seeping between the hanging cloth and the outer soil, thus preventing the earth pressure box from becoming unusable. Because it is directly embedded during the wall ties process, it avoids the problem of inaccurate measurement caused by the soil arching effect in the drilling method. It has wider applicability; compared with the horizontal pushing method, before pulling the rope, the rods and earth pressure box are vertical, almost touching the steel cage, with a smaller lateral dimension, making it less prone to scratching during the lowering of the steel cage. Attached Figure Description

[0034] Figure 1 This is a side view of the earth pressure box embedding device for the underground continuous wall of the present invention during implementation;

[0035] Figure 2 This is a front view of the earth pressure box embedding device on the side of the underground continuous wall according to the present invention during implementation;

[0036] Figure 3 The working principle diagram of the earth pressure box embedding device on the side of the underground continuous wall of the present invention is shown in Figure (1);

[0037] Figure 4 This is a schematic diagram (2) of the working principle of the earth pressure box embedding device on the side of the underground continuous wall of the present invention;

[0038] In the diagram: 1—rope; 2—hook; 3—pole frame; 4—push rod; 5—roller; 6—earth pressure box hanging bag; 7—spring; 8—horizontal reinforcement of the steel cage; 9—vertical reinforcement of the steel cage; 10—soil outside the trench wall. Detailed Implementation

[0039] To better understand the present invention, further detailed descriptions are provided below in conjunction with specific embodiments and accompanying drawings.

[0040] As attached Figure 1 Appendix Figure 2 As shown, a simple underground continuous wall lateral earth pressure box embedding device includes a rope 1, a hook 2, a rod 3, a push rod 4, a roller 5, an earth pressure box hanging bag 6, and a spring 7; characterized in that: the rope 1 is connected to the rod 3 by binding; the rod 3 is connected to the hook 2 by hinge; the rod 3 is connected to the push rod 4 and the spring by hinge; and the earth pressure box hanging bag 6 is connected to the rod 3 by binding.

[0041] The frame 3 is welded from two vertical poles and a single horizontal pole. The vertical poles are parallel and spaced slightly larger than the diameter of the earth pressure box, matching the lateral dimension of the earth pressure box hanging bag 6. A hinge point is located near the lower middle of the vertical pole for connection to the push rod 4, and further down, it protrudes outwards and connects to the push rod 4 via a spring 7. The upper end of the vertical pole is hinged to the hook 2, and the lower end has a pre-drilled hole (or groove, protrusion) for securing the cloth rope of the earth pressure box hanging bag 6. The lower horizontal pole is located slightly above the end of the vertical pole, serving both to fix the vertical pole and to connect to the rope 1 in the middle.

[0042] There are two push rods 4, which are distributed horizontally and are hinged to the two vertical rods of the frame 3 respectively, and connected to the frame by springs 7. The lower end of the push rod 4 is fixedly connected by a horizontal bar, and a roller 5 (or several horizontally evenly distributed rollers) is fitted on the horizontal bar to reduce the friction when the lower end of the push rod 4 moves up and down along the back of the earth pressure box hanging bag 6.

[0043] The earth pressure box hanging bag 6 is tied to the pre-reserved hole (or groove, protrusion) at the bottom of the vertical pole of the pole frame 3 by a cloth rope.

[0044] Hook 2 has two vertical bars connected by a horizontal bar, and is hinged to the vertical bar of frame 3 at the end of the horizontal bar. The two hooks 2 are symmetrically distributed on the center line of the horizontal bar and are a certain distance apart to ensure the relative stability and uniform stress of the "hook-horizontal bar-reinforcing cage horizontal bar" system when the hook 2 is fixed to the horizontal bar of the reinforcing cage 8.

[0045] Taking a 1200mm wide diaphragm wall trench section, an earth pressure box with an outer diameter of 108mm, and an burial depth of 30m as an example: Rope 1 can be 32m long; the vertical bar spacing of hooks 2 can be 10-11cm, the vertical bar length can be 5-6cm, the inner diameter of the hooks is about 3cm, and the horizontal bar length is the spacing value; the vertical bar spacing of the frame 3 can be 11-12cm, and the vertical bar length needs to be determined based on the horizontal spacing from the horizontal reinforcement of the steel cage to the outer soil surface, which is generally about 5-10cm. Therefore, the vertical bar length should not be less than this dimension, and can be 12cm; the push rod 4 is hinged to the frame 3 vertically near the middle, and the horizontal distance between it and the vertical bar of the frame 3 is about 1m. ~1.5cm; the bottom of the push rod 4 should touch the upper part of the earth pressure box, so the vertical length of the push rod can be about 8cm; the horizontal spacing of the push rod 4 can be 12~13cm, and the size of the horizontal bar is this spacing; the horizontal dimension of the roller 5 can be slightly smaller than the earth pressure box hanging bag 6, which can be 9~10cm; the earth pressure box hanging bag 6 is square with a side length of 11cm; the initial size of the spring can be slightly smaller than the horizontal spacing between the rod frame 4 and the push rod 3, which is about 1cm, and its connection position with the rod frame 3 can be at the lower 1 / 4 length of the vertical rod of the rod frame 3.

[0046] A method for using a simple lateral earth pressure cell embedding device for underground continuous walls, the steps of which are as follows:

[0047] S1, fix hook 2 to the horizontal reinforcing bar. The fixing of hook 2 to the horizontal reinforcing bar 8 can be completed before or during the lowering of the reinforcing cage, and can be fixed by binding straps or welding.

[0048] In step S1, the fixing of hook 2 and transverse steel bar 8 can be completed before or during the lowering of the steel cage. It can be fixed by binding straps or by welding.

[0049] S2, after the pole 3 hangs down naturally, place the earth pressure box in the hanging bag.

[0050] In step S2, "the support frame 3 hangs down naturally." Compared to the horizontal advancement method, without step S3, the lateral dimensions of the entire device are smaller, making it less likely to scrape against the outer soil during lowering and cause the device to detach. Furthermore, the length of the vertical rod in support frame 3 is easier to control; it only needs to be slightly longer than the maximum possible horizontal distance between the outer soil and the reinforcing cage. However, with the horizontal advancement method, if the lateral guide rod is too long, the device is prone to scraping against the outer soil during lowering of the reinforcing cage; if the lateral guide rod is too short, its thrust is small, which may not ensure close contact between the earth pressure cell and the outer soil.

[0051] S3, the earth pressure box conductor is led to the top of the steel cage during the lowering process. After the steel cage is lowered, rope 1 is lifted, causing the pole frame 3 to rotate clockwise.

[0052] In step S3, tensioning rope 1 is performed in two steps:

[0053] S31, as attached Figure 3 As shown, the earth pressure box hanging bag 6 and the push rod 4 both move with the frame 3. Because the connection between the earth pressure box hanging bag 6 and the frame 3 is flexible, the earth pressure box hanging bag 6 moves vertically downwards during the rotation of the frame 3 until it comes into contact with the roller 5. As the frame 3 continues to rotate clockwise, the bottom of the earth pressure box inside the earth pressure box hanging bag 6 will be the first to contact the outer soil 10.

[0054] S32, as attached Figure 4 As shown, the rope continues to be pulled up. As the pole 3 rotates clockwise, the earth pressure box gets closer and closer to the outer soil 10 until it is completely against the outer soil 10. The spring 7 will be stretched further, and the roller 5 will apply a normal force to make the earth pressure box stick to the outer soil 10. This avoids the disadvantage of concrete intrusion between the hanging cloth and the outer soil in the hanging cloth method. In addition, compared with the horizontal pushing method, when the pole (3) has a certain size, the earth pressure box can move a larger distance horizontally, which can ensure that the earth pressure box reaches the outer soil. If the horizontal pushing method also has this pushing stroke, the horizontal guide rod needs to be long enough, but it is easy to cause scraping during the lowering of the steel cage.

[0055] S4. When rope 1 can no longer be lifted, tie the tensioned rope 1 to the horizontal reinforcement bar at the top of the steel cage and wait for concrete pouring.

[0056] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A simple device for embedding lateral earth pressure cells in underground continuous walls, characterized in that: The installation device is installed on the steel cage of the underground continuous wall, and the installation device is located between the steel cage and the soil (10) outside the trench wall of the foundation pit. The burial device includes a rope (1), a hook (2), a pole frame (3), a push rod (4), an earth pressure box hanging bag (6), and a spring (7); The rope (1) is connected to the lower end of the pole frame (3), and the upper end of the pole frame (3) is hinged to the hook (2). The hook (2) is fixed to the transverse steel bar (8) of the steel cage. The earth pressure box hanging bag (6) is hung at the lower end of the pole frame (3); The upper end of the push rod (4) is hinged to the rod frame (3). When the rod frame (3) is lifted, the earth pressure box hanging bag (6) contacts the lower end of the push rod (4). A spring (7) is also provided between the push rod (4) and the rod frame (3). Among them, the hook (2), the rod frame (3), and the push rod (4) are all frame structures, each containing a pair of vertical rods and a horizontal rod. The pair of vertical rods are parallel to each other, and the horizontal rod is located between the lower ends of the pair of vertical rods. The upper part of the vertical rod of the hook (2) is the hook body, which is hung on the horizontal steel bar (8) of the steel cage; The upper end of the vertical rod of the pole frame (3) is hinged to both ends of the horizontal rod of the hook (2), the rope (1) is fixed to the horizontal rod of the pole frame (3), and the earth pressure box hanging bag (6) is hung at the lower ends of the two vertical rods of the pole frame (3). The vertical rod of the push rod (4) has an inverted "L" structure. The upper end of the vertical rod of the push rod (4) is hinged to the middle and lower position of the vertical rod of the frame (3). One vertical rod of the push rod (4) corresponds to one vertical rod of the frame (3).

2. The simplified underground continuous wall lateral earth pressure cell embedding device according to claim 1, characterized in that: The push rod (4) has a roller (5) fitted on its crossbar to reduce the friction between it and the earth pressure box hanging bag (6).

3. The method of using the simplified underground continuous wall lateral earth pressure cell embedding device according to any one of claims 1-2, characterized in that, Includes the following steps: S1, fix the hook (2) to the transverse steel bar (8) of the steel cage; S2, after the hook (2), rod frame (3), and push rod (4) hang down naturally, place the earth pressure box in the earth pressure box hanging bag (6); S3, the earth pressure box wire is led to the top of the steel cage during the lowering process of the steel cage. After the steel cage is lowered, the rope (1) is lifted up, so that the pole frame (3) rotates clockwise. S4. When the earth pressure box hanging bag (6) is completely pressed against the soil (10) on the outside of the trench wall, the rope (1) cannot be lifted further. At this time, the tensioned rope (1) is tied to the horizontal steel bar at the top of the steel cage and waits for the concrete to be poured.

4. The method of using the simplified underground continuous wall lateral earth pressure cell embedding device according to claim 3, characterized in that: The hook (2) is fixed to the transverse steel bar (8) of the steel cage before or during the lowering of the steel cage, using binding straps or welding.

5. The method of using a simple underground continuous wall lateral earth pressure cell embedding device according to claim 3, characterized in that: In step S3, the tensioning of the rope (1) is carried out in two steps: S31, the earth pressure box hanging bag (6) and the push rod (4) move with the rod frame (3). Since the connection between the earth pressure box hanging bag (6) and the rod frame (3) is flexible, the earth pressure box hanging bag (6) is vertically downward during the rotation of the rod frame (3) until the earth pressure box hanging bag (6) abuts against the roller (5). As the rod frame (3) continues to rotate clockwise, the bottom of the earth pressure box inside the earth pressure box hanging bag (6) will contact the outer soil body (10) first. S32, continue to lift the rope. As the pole (3) rotates clockwise, the earth pressure box and the outer soil (10) become closer and closer until the earth pressure box is completely against the outer soil (10). The spring (7) will stretch further and apply normal force through the roller (5) to ensure that the earth pressure box is close to the outer soil (10).

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