A device for simulating the formation of shield tail gap by synchronous grouting

Abstract

The present invention discloses a device for simulating the formation of a gap at the tail of a shield during synchronous grouting, belonging to the technical field of test equipment for synchronous grouting of shield segments. The device comprises a segment model and a soil box having an uncovered box-like structure. The segment model is buried in the soil of the soil box, and a pressure mechanism for applying pressure to the soil is provided above the soil box. Two parallel retaining plates are vertically arranged in the soil box. The segment model is formed by axially movably connecting two or more arc-shaped segments, each segment being provided with a first through hole axially extending through the body, and the first through holes of all segments are connected as grouting channels. The segment model is located between the two retaining plates, and the two side walls of each segment are respectively matched with the gap between the two retaining plates. An independent lifting mechanism is provided below each segment for lifting and lowering the corresponding segment. The segment model of the present invention moves vertically, which reduces the size of the device and the floor space occupied.

Description

Technical Field

[0001] The invention relates to the technical field of shield segment synchronous grouting test equipment, in particular to a device for simulating the formation of a synchronous grouting shield tail gap. Background Art

[0002] After more than two hundred years of evolution and development, shield tunneling methods and technologies have become very mature today. They can not only realize mechanized construction, but also cause less disturbance to the surrounding strata and structures. Therefore, shield tunneling has been widely used in the construction of urban subway tunnels at home and abroad.

[0003] At present, most of the research on synchronous grouting of shield tunnel segments in China remains at the theoretical stage, and the few experimental studies are difficult to combine with the actual construction conditions of the tunnel, and cannot more realistically reflect the synchronous grouting working conditions of the segments for simulation. The main difficulty is that it is impossible to simulate the formation of the shield tail gap more realistically, and the diffusion morphology and defects of the slurry are difficult to observe. Therefore, in order to explore the diffusion morphology of the synchronous grouting slurry in actual engineering, it is necessary to develop a device for observing the synchronous grouting experiment of shield tunnel segments. The existing synchronous grouting prototype experimental equipment is a horizontal push-pull type (i.e., the shield tail shell is pulled horizontally to form a grouting gap between the segment model and the soil), which is bulky and complicated to operate. The pulling of the equipment requires complex equipment and a large site for operation, which is very inconvenient in terms of funding and operation procedures. Summary of the Invention

[0004] In order to solve at least one of the above technical problems, the purpose of the present invention is to provide a device that simulates the formation of the synchronous grouting shield tail gap. The pipe segment model of the present invention moves vertically, which can reduce the size of the device and reduce the floor space.

[0005] The technical solutions of the present invention are as follows:

[0006] A device for simulating the formation of a synchronous grouting shield tail gap comprises a soil box and a segment model, wherein the soil box is a box-shaped structure without a lid, the segment model is buried in the soil of the soil box, a pressure mechanism is provided above the soil box for applying pressure to the soil in the soil box, and two parallel retaining plates are vertically arranged in the soil box; the segment model is formed by axially movably connecting two or more arc-shaped segments, each segment is provided with a first through hole axially penetrating the body, and the first through holes of all segments are connected as a grouting channel; the segment model is located between the two retaining plates, and the two side walls of each segment are respectively matched with the gaps of the two retaining plates to prevent soil from sliding from the gaps between the side walls of the segment and the retaining plates to the bottom of the segment model and affecting the subsequent settlement of the segment; an independent lifting mechanism is provided below each segment for lifting the corresponding segment.

[0007] As a specific embodiment of the present invention, the upper ends of the two side walls of the pipe segment facing the retaining plate are flush with the upper ends of the retaining plate (located on the same horizontal plane), and the soil above the side walls of the pipe segment can be well connected with the soil around the retaining plate, avoiding the separation of the soil by the retaining plate to damage the overall load-bearing structure of the soil and the overall collapse of the upper soil when the pipe segment descends.

[0008] As a specific embodiment of the present invention, second through holes are provided on opposite sides of the box body, and the two ends of the retaining plate and the segment model extend out of the soil box through the second through holes and are sealed with the second through holes. This avoids taking additional measures to prevent soil from entering the bottom of the segment model from both ends of the segment model.

[0009] Furthermore, the two retaining plates can be moved horizontally toward or away from each other, thereby varying the distance between them to accommodate segment models of varying sizes. In a specific embodiment, sealing plates are provided at both ends of the retaining plates. The sealing plates are at least as high as the second through-hole and are slidably connected to the wall of the soil box to seal the second through-hole, thereby preventing soil from leaking out of the second through-hole.

[0010] The lifting mechanism of the present invention can be a jack or other existing lifting mechanisms, but it should be noted that for each segment, it must adopt surface support or multi-point support to avoid shaking and colliding with the soil during its descent, thereby affecting the gap shape. The present invention proposes a new and simple lifting mechanism, which includes a balloon and multiple elastic elements, such as springs. The multiple elastic elements are symmetrically arranged along the axial half-section of the segment to apply equal force to both ends of the segment. One end of the elastic element is fixedly connected to the bottom of the soil box, and the other end is fixedly connected to the segment. The balloon is at least partially able to expand along the height direction of the soil box and the expanded part is symmetrical along the axial half-section of the segment, thereby applying a vertical force to the segment to avoid uneven force causing the segment to tilt. Liquid can be used to fill the balloon.

[0011] The beneficial effects of the present invention are as follows:

[0012] 1) The present invention's device differs significantly from existing synchronous grouting gap-forming devices in structure. The segment model of the present invention moves vertically, rather than horizontally, reducing floor space. Existing devices create grouting gaps through horizontal movement, requiring significant pulling force to pull the shield tail model horizontally. The associated pulling mechanism is bulky, occupies significant floor space, and consumes significant energy. However, the present invention utilizes vertical movement of the segment model to create grouting gaps, resulting in a smaller footprint.

[0013] 2) As is known, the depth of the soil filled in the soil box is difficult to reach the actual depth of the soil burial, and the soil is always pressurized by external pressure to simulate the soil pressure in actual working conditions. When the shield tail gap is formed by dragging, under extremely high soil pressure loads, dragging will cause excessive disturbance to the shallower covering soil, making it difficult for the formed shield tail gap and the diffusion law of the slurry to simulate the formation of the shield tail gap and the diffusion of the slurry under the covering soil at the actual burial depth. The present invention uses a descending method to form the shield tail gap, which can reduce the disturbance caused to the soil by excessive pressure and more realistically simulate the formation of the shield tail gap and the diffusion law of the slurry in the soil and the shield tail gap. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of the shield tail gap forming device;

[0015] Figure 2 This is the layout diagram of the earth box retaining plate segment model;

[0016] Figure 3 It is a structural diagram of the soil box;

[0017] Figure 4 It is a structural diagram of the segment model;

[0018] Figure 5 It is a structural diagram of the retaining wall;

[0019] In the figure, soil box 1, segment model 2, pressure mechanism 3, retaining plate 4, lifting mechanism 5, soil 6,

[0020] The second through hole 101, the tube sheet 201, the sealing plate 401, the fastening bolt 402, the balloon 501, the elastic element 502,

[0021] First through hole 2011 and threaded hole 4011. DETAILED DESCRIPTION

[0022] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0023] Example 1

[0024] Please refer to Figures 1 and 2 , Figure 1 This is a schematic diagram of the shield tail gap forming device. Figure 2This is a layout diagram of a soil box and retaining plate segment model. This device for simulating the formation of a synchronous grouting shield tail gap includes a soil box 1, a segment model 2, a pressure mechanism 3, a retaining plate 4, and a lifting mechanism 5. The soil box 1 is an uncovered box-like structure, and the segment model 2 is buried in the soil 6 within the soil box 1. The pressure mechanism 3 is located above the soil box 1 to apply pressure to the soil 6 within the soil box 1 to simulate stratum pressure. Each segment 201 in the segment model 2 is equipped with an independent lifting mechanism 5 below it for raising and lowering the corresponding segment 201.

[0025] Please refer to Figure 3 , Figure 3 The soil box 1 has two opposite side walls provided with second through holes 101 penetrating the body.

[0026] Please refer to Figure 4 , Figure 4 2 is a structural diagram of the segment model. The segment model 2 is composed of multiple arc-shaped segments 201 that are axially movably connected. Therefore, two adjacent segments 201 can move radially along the segment 201 (i.e., move along the height direction of the soil box) to form a dislocation. Each segment 201 is provided with a first through hole 2011 that axially penetrates the body. The first through holes 2011 of all segments 201 are connected as grouting channels.

[0027] Please further combine Figure 2 , Figure 2 1 is a layout diagram of a soil box retaining plate segment model. There are two retaining plates 4, which are parallel to each other and are both vertically arranged in the soil box 1. The segment model 2 is located between the two retaining plates 4 and the two side walls of each segment 201 facing the retaining plates 4 are respectively fitted with the two retaining plates 4 to prevent the soil from sliding from the gap between the side walls of the segment 201 and the retaining plates 4 to the bottom of the segment model 2 and affecting the later settlement of the segment 201. In addition, the upper ends of the two side walls of the segment 201 facing the retaining plates 4 are flush with the upper ends of the retaining plates 4 (located on the same horizontal plane). Therefore, the soil above the side walls of the segment 201 facing the retaining plates 4 can be well connected with the soil around the retaining plates 4, avoiding the separation of the soil around the segment by the retaining plates 4, which leads to damage to the overall mechanical structure of the soil (this can easily cause the soil above the side walls of the segment 201 facing the retaining plates 4 to collapse with the segment when the segment settles due to the lack of supporting force of the side wall soil, forming a collapse shape different from the actual working condition).

[0028] The box body 1 has second through holes 101 on opposite sides. The retaining plate 4 and the ends of the segment model 2 extend out of the box body 1 through the second through holes 101 and are sealed with the second through holes 101 to prevent soil from leaking out of the box body 1. Figure 1As can be seen, the segment model 2, the two retaining plates 4, and the bottom plate of the soil box 1 form an annular cavity structure with openings at both ends. When filling the soil box 1, soil easily enters this annular cavity structure through the openings at both ends, thereby affecting the vertical movement of the segment 201. If the ends of this annular cavity structure are sealed, it will be difficult to inspect and repair the lifting mechanism 5 located within this annular cavity structure. With the arrangement of this embodiment, there is no need to seal the ends of the annular cavity structure, which can prevent soil from entering the annular cavity structure while facilitating the inspection and repair of the lifting mechanism 5.

[0029] In addition, the width of the second through hole 101 is greater than the width of the segment model 2. Therefore, the two retaining plates 4 have space to move horizontally closer or further apart, so that the distance between the two retaining plates 4 can be changed to accommodate segment models 2 of different sizes. Specifically, each retaining plate 4 is provided with a sealing plate 401 at both ends for sealing the second through hole 101. The sealing plate 401 is parallel to the wall of the soil box 1 having the second through hole 101. The height of the sealing plate 401 is higher than the height of the second through hole 101, and the sealing plate 401 is provided with a clearance fit with the wall of the soil box 1 so that the two can slide relative to each other. When in use, the retaining plate 4 can be moved to adapt to the width of the segment model 2. In addition, the sealing plate 401 is provided with a threaded hole 4011. When the retaining plate 4 is moved to a certain position, the positioning bolt 402 is threadedly connected to the threaded hole 401, and one end of the positioning bolt 401 presses against the wall of the soil box 1, thereby positioning the retaining plate 4 in the soil box 1.

[0030] The lifting mechanism 5 includes a balloon 501 and four elastic elements 502 (springs). The four elastic elements 502 are symmetrically arranged along the axial half-section of the pipe segment 201 so as to apply equal forces to both ends of the pipe segment 201. One end of the elastic element 502 is fixedly connected to the bottom of the soil box 1, and the other end is fixedly connected to the pipe segment 201. The balloon 501 expands along the height direction of the soil box 1 and the expanded part is symmetrical along the axial half-section of the pipe segment 201, thereby applying vertical force to the pipe segment 201 to avoid tilting of the pipe segment due to uneven force.

[0031] One method of using the device is as follows:

[0032] First, install the device: install the lifting mechanism in the soil box, then install the segment model, install the retaining wall, then inflate the balloon to lift the segment model until the upper end of the segment side wall is flush with the upper end of the retaining wall (at this time the elastic element is in a tensioned state), then fill the soil box with soil, and finally install the pressure mechanism.

[0033] Next, the soil is pressurized using a pressure mechanism, and finally a pipe segment is made to drop vertically by releasing the pressure on the balloon (the tension of the elastic element 502 can assist the downward movement of the pipe segment). At this time, a gap is formed between the dropped pipe segment and the upper soil as a grouting space. After the pipe segment 201 drops, the first through hole 2011 is connected to the grouting space, and a grouting experiment can be carried out on it using grouting equipment.

[0034] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any technician familiar with this profession can make some changes or modifications to equivalent embodiments of the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A device for simulating the formation of a synchronous grouting shield tail gap, comprising a soil box and a segment model, wherein the soil box is a box-like structure without a cover, the segment model is buried in the soil of the soil box, and a pressure mechanism is provided above the soil box to apply pressure to the soil in the soil box, characterized in that: Two parallel retaining plates are vertically arranged in the soil box; the segment model is composed of two or more arc-shaped segments axially connected, each segment is provided with a first through hole axially penetrating the body, and the first through holes of all segments are connected as grouting channels; the segment model is located between the two retaining plates, and the two side walls of each segment are respectively fitted with the two retaining plates; an independent lifting mechanism is provided under each segment for lifting the corresponding segment.

2. The device for simulating the formation of a synchronous grouting shield tail gap according to claim 1, characterized in that: The upper ends of the two side walls of the pipe segment adjacent to the retaining plate are flush with the upper end of the retaining plate.

3. The device for simulating the formation of a synchronous grouting shield tail gap according to claim 1, characterized in that: The soil box is provided with second through holes penetrating the main body on opposite sides, and the two ends of the retaining plate and the segment model extend out of the soil box through the second through holes and are sealed with the second through holes.

4. The device for simulating the formation of a synchronous grouting shield tail gap according to claim 3, characterized in that: The two retaining plates can be moved toward or away from each other horizontally.

5. The device for simulating the formation of a synchronous grouting shield tail gap according to claim 4, characterized in that: Sealing plates are provided at both ends of the retaining plate. The height of the sealing plates is not lower than the height of the second through hole and the sealing plates are slidably and sealedly connected to the wall of the soil box.

6. The device for simulating the formation of a synchronous grouting shield tail gap according to any one of claims 1 to 5, characterized in that: The lifting mechanism includes a balloon and multiple elastic elements, which are symmetrically arranged along the axial half-section of the pipe segment, and one end of the elastic element is fixedly connected to the bottom of the soil box, and the other end is fixedly connected to the pipe segment; at least part of the balloon can expand along the height direction of the soil box, and the expanded part is symmetrical along the axial half-section of the pipe segment.

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