Simulation test platform and simulation test method for shield excavation and soil settlement monitoring

Abstract

The present invention relates to a shield excavation and soil settlement monitoring simulation test platform and simulation test method, wherein the simulation test platform comprises a box, an excavation simulation system and a soil settlement monitoring system, wherein the excavation simulation system is installed in the box, and comprises a built-in steel cylinder, wherein a plurality of annular baffles concentric with the built-in steel cylinder are evenly arranged at intervals on the periphery of the built-in steel cylinder, and an outer annular water layer and an inner annular water layer concentric with the built-in steel cylinder are installed between adjacent annular baffles; the soil settlement monitoring system comprises at least one row of single-point displacement meters. The present invention can at least simulate the control effect of the shield construction excavation gap and the shield tail gap filling conditions on the stratum settlement, and further can study the settlement law of the soil caused by the shield excavation, and correct the soil settlement monitoring results and study the correction law. The platform is easy to manufacture and assemble, and can be dismantled and reused.

Description

Technical Field

[0001] The invention relates to the technical field of shield construction, and in particular to a shield excavation and soil settlement monitoring simulation test platform and a simulation test method. Background Art

[0002] One of the important measures to control settlement when the shield method is used in subway tunnel construction is grouting filling. At present, almost most projects use the shield tail gap filling, and rarely consider the excavation gap filling. The ground settlement effect caused by the excavation gap cannot be ignored in projects with high settlement requirements. High-precision and automated monitoring of ground displacement caused by shield construction is an important guarantee for the shield to cross major risk sources to achieve micro-disturbance and micro-settlement control. At present, more and more deep ground displacement monitoring is being carried out in actual projects. At present, magnetic ring displacement meters, multi-point displacement meters, and single-point displacement meters are widely used for deep displacement monitoring. Regardless of the type of monitoring equipment, it is necessary to drill holes in the formation, bury the equipment, and backfill sand for monitoring. The on-site drilling is too deep, that is, the drilling depth exceeds the design depth, and the backfill sand of the super-deep part is very different from the original soil. In this case, the displacement meter actually monitors the settlement value of the backfill sand layer in the deep hole sleeve, rather than the actual settlement of the original formation at that location.

[0003] In order to clarify the control effect of the filling degree of the shield excavation gap and the shield tail gap on the ground settlement, to eliminate the settlement difference between the backfill sand and the surrounding strata, or to establish a comparative relationship between the filling degree and the elastic modulus of the filling material in numerical simulation, it is crucial to design a similar simulation experimental platform that can simulate shield excavation grouting filling and perform deep soil settlement monitoring and correction. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the existing technology and provide a shield excavation and soil settlement monitoring simulation test platform and simulation test method, which can at least simulate the control effect of shield construction excavation gap and shield tail gap filling on stratum settlement, and further study the settlement law of soil caused by shield excavation, and correct the soil settlement monitoring results and study the correction law. The platform is easy to manufacture and assemble, and can be dismantled and reused.

[0005] The present invention provides a shield excavation and soil settlement monitoring simulation test platform, comprising a box, an excavation simulation system and a soil settlement monitoring system, wherein:

[0006] The box is filled with undisturbed soil;

[0007] The excavation simulation system is installed in the box, including an internal steel cylinder, which serves as the bearing foundation of the excavation simulation system, and a plurality of annular baffles are evenly arranged at intervals on the periphery thereof, and an outer annular water layer and an inner annular water layer are installed between adjacent annular baffles, which are concentric with the internal steel cylinder, and the outer annular water layer is provided with water injection holes and grouting holes connected to the interior thereof, and the inner annular water layer is provided with water injection holes connected to the interior thereof;

[0008] The soil settlement monitoring system comprises at least one row of single-point displacement meters, and the single-point displacement meters are buried in the original soil.

[0009] As an improvement, the box body adopts a three-dimensional steel plate soil box with an open top, and a vertical slide groove is opened on the left and right side plates of the soil box for placing the two ends of the built-in steel cylinder, so that the built-in steel cylinder can slide up and down in the vertical slide groove, thereby adjusting the layout height of the excavation simulation system.

[0010] As an improvement, the vertical chute is provided with a vertical chute sealing plate for sealing the internal filling.

[0011] As an improvement, the soil settlement monitoring system includes a first row of single-point displacement meters and a second row of single-point displacement meters. The area around the first row of single-point displacement meters is backfilled with original soil, and the ultra-deep sections of the second row of single-point displacement meter holes are backfilled with test soil.

[0012] As an improvement, the first row of single-point displacement meters and the second row of single-point displacement meters are respectively fixed to the upper part of the box body by single-point displacement meter fixing rods.

[0013] As an improvement, the first row of single-point displacement meters and the second row of single-point displacement meters are respectively provided with a plurality of single-point displacement meters, and the buried depths of the respective single-point displacement meters are different.

[0014] As an improvement, the spacing distance between the annular partitions is the width of the simulated segment of the shield tunnel.

[0015] As an improvement, both ends of the built-in steel cylinder of the excavation simulation system are fixed at the test height by supporting cross bars.

[0016] The present invention also provides a simulation test method according to the simulation test platform, comprising the following steps:

[0017] S1: Simulation of shield tunneling starts;

[0018] S2: the water release from the outer ring water layer of the previous ring simulates the excavation gap caused by the cutterhead excavation;

[0019] S3: After a certain period of time of excavation gap, water is released from the inner water layer of the previous ring to simulate the shield tail gap caused by the shield tail coming out;

[0020] S4: After the excavation gap and the shield tail gap work together for a certain period of time, grouting is performed on the outer ring water layer of the previous ring, and different filling degrees are simulated by designing and controlling the grouting amount;

[0021] S5: repeating steps S2-S4, draining and grouting the next ring of water layers that have reached the designed excavation time;

[0022] S6: Repeat step S5, and set the actual time difference between the drainage of the annular water layer and the grouting filling in different rings, and perform simulated excavation in sequence to realize the advancement of the shield.

[0023] As an improvement, the excavation gap and the shield tail gap are fixed, and the soil settlement data at different depths are collected by single-point displacement meters. The differences in the single-point displacement meter settlement values ​​of the original soil and the ultra-deep backfill soil in the same depth soil layer are compared, and the correction rules of the single-point displacement meter settlement monitoring values ​​of different ultra-deep soils are studied.

[0024] Beneficial effects: After adopting the above technical solution, the present invention has the following technical effects compared with the prior art:

[0025] (1) The present invention simulates the pipe segment by means of a fixed internal steel cylinder, the outer annular water layer simulates the excavation gap, the inner annular water layer simulates the shield tail gap, and grouting is used to simulate the filling condition.

[0026] (2) By draining water from different rings of the annular water layer and grouting filling according to the actual set time difference, simulated excavation is carried out in sequence to realize the movement and advancement of the shield.

[0027] (3) The soil settlement was monitored by using a single-point displacement meter. Under different excavation gaps and shield tail gaps, soil settlement data at different depths were collected by using a single-point displacement meter to study the settlement law of soil caused by shield tunnel excavation.

[0028] (4) The single-point displacement meter is used to monitor soil settlement. Under certain conditions of excavation gap and shield tail gap, the soil settlement data at different depths are collected by using the single-point displacement meter. The difference in settlement of the original soil and ultra-deep backfill soil at the same depth is compared, and the correction law of the settlement value monitored by the single-point displacement meter of different ultra-deep boreholes is studied. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a three-dimensional perspective view of an embodiment of the simulation test platform of the present invention;

[0030] Figure 2 It is a structural schematic diagram of an implementation mode of the excavation simulation system of the present invention;

[0031] Figure 3 It is a structural schematic diagram of an implementation method of the construction gap of the present invention.

[0032] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application, but do not constitute a limitation of the present invention. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the embodiments of the present invention more clearly understood, the embodiments of the present invention are further described in detail below in conjunction with the embodiments and drawings. Here, the illustrative embodiments of the present invention and their descriptions are used to explain the present invention, but are not intended to limit the present invention.

[0034] In the description of the present invention, it should be understood that terms such as “upper”, “lower”, “front”, “back”, “left”, “right”, “top”, “bottom”, “inside” and “outside” indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device, component or structure must have a specific direction, be constructed or operate in a specific direction, and should not be understood as a limitation on the present invention.

[0035] It is also necessary to understand that the terms "include / comprise", "consist of..." or any other variation thereof are intended to cover non-exclusive inclusion, so that a product, device, process or method including a series of elements includes not only those elements, but also other elements not explicitly listed when necessary, or also includes elements inherent to such product, device, process or method. In the absence of further restrictions, the elements defined by the sentence "include / comprise...", "consist of..." do not exclude the presence of other identical elements in the product, device, process or method including the elements.

[0036] The specific implementation method of the present invention will be further described below with reference to the accompanying drawings.

[0037] "Left" in the present invention refers to the left side in the longitudinal direction of the tunnel facing the view, "right" refers to the right side in the longitudinal direction of the tunnel facing the view, "up" refers to the side facing the view close to the tunnel top plate, "down" refers to the side facing the view close to the tunnel bottom plate, "inside" refers to the side facing the view close to the underground reservoir, "outside" refers to the side facing the view close to the tunnel, "longitudinal" refers to the direction parallel to the direction of the tunnel, and "transverse" refers to the direction perpendicular to the direction of the tunnel.

[0038] See also Figure 1 , Figure 1 The present invention provides a perspective view of the three-dimensional structure of a shield excavation and soil settlement monitoring simulation test platform, including a box 100, an excavation simulation system 200 and a soil settlement monitoring system 300. The simulation test platform of the present invention can at least simulate the control effect of the shield construction excavation gap and the shield tail gap filling on the stratum settlement.

[0039] Specific as Figure 1 As a specific example, according to the similar simulation principle, the box 100 adopts a three-dimensional steel plate soil box with an open top, having a base bottom plate 104, and the soil box is filled with original soil to simulate the characteristics of shield excavation strata. The soil box can be made of steel plates welded, which is easy to manufacture and assemble.

[0040] In a specific example, a vertical slide groove 101 is opened on each of the left and right side plates of the soil box for placing the two ends of the built-in steel cylinder 201 described later, so that the built-in steel cylinder can slide up and down in the vertical slide groove, thereby adjusting the layout height of the excavation simulation system, that is, adjusting the layout height of the excavation system, thereby controlling the actual simulated burial depth.

[0041] In a specific example, the vertical chute 101 is equipped with a vertical chute cover plate 102 for sealing the internal filling. The chute cover plate 102 can be vertically inserted into the vertical chute 101, or installed on the outside of the vertical chute 101 to add a fastening device.

[0042] In one specific example, see Figure 2 The excavation simulation system 200 is installed in the box 100, including a built-in steel cylinder 201. The built-in steel cylinder is an integral circular steel cylinder, which is not only a component of the excavation simulation system, but also a supporting component as the bearing foundation of the excavation simulation system. A number of concentric annular partitions 202 are evenly arranged at intervals on its periphery. In this example, the annular partitions are arranged according to the width of the simulated segment of the shield tunnel (separating the axial extrusion force transmission of the segment), and the number of simulated segment rings is designed according to the actual situation (designed as 3 rings in the figure). There are 4 annular partitions 202 in total (including the two ends). Considering the stress concentration near the side wall of the soil box, the excavation simulation system must maintain a reasonable distance from the side wall of the soil box.

[0043] An outer annular water layer 203 and an inner annular water layer 204 concentric with the built-in steel cylinder are arranged in concentric circles at the position of each annular segment separated by the annular baffle 202. The outer annular water layer is provided with a water injection hole 205 and a grouting hole 206 connected to the interior thereof, and the inner annular water layer is provided with a water injection hole 207 connected to the interior thereof.

[0044] Among them, the inner annular water layer 204 is used to simulate the outer diameter of the shield machine. In the simulated excavation stage, water is released through the water injection hole 207 to control the thickness of the inner annular water layer 204 to simulate the radius changes of the front shield, middle shield and tail shield of the shield through the same ring segment; the outer annular water layer 203 is used to simulate the excavation gap and its filling control during the shield excavation process. The excavation gap is simulated by draining water through the water injection hole 205 of the outer annular water layer 203, and the excavation gap filling is simulated through the grouting hole 206.

[0045] See also Figure 1In one example, the soil settlement monitoring system 300 includes at least one row of single-point displacement meters, and the single-point displacement meters are buried in the original soil.

[0046] In an improved example, the soil settlement monitoring system 300 includes a first row of single-point displacement meters 301 and a second row of single-point displacement meters 302. The areas around the first row of single-point displacement meters are backfilled with original soil, and the ultra-deep sections of the second row of single-point displacement meter holes are backfilled with test soil.

[0047] In one example, the first row of single-point displacement meters and the second row of single-point displacement meters are respectively installed and fixed to the upper part of the box body by using single-point displacement meter fixing rods 303.

[0048] In an improved example, the first row of single-point displacement meters and the second row of single-point displacement meters are respectively provided with a plurality of single-point displacement meters, and the buried depths of the single-point displacement meters are different.

[0049] Two rows of single-point displacement meters are set on the upper part of the box and fixed by single-point displacement meter fixing rods. The area around the first row of single-point displacement meters is backfilled with original soil, and the holes of the second row of single-point displacement meters are backfilled with experimental soil. This simulates the drilling monitoring experiment under different ultra-deep conditions and is used as a comparative experiment to study the settlement law of soil caused by shield excavation, as well as to correct the soil settlement monitoring results and study the correction law. This will be further elaborated later.

[0050] In the present invention, the excavation simulation system (taking the three-ring simulation segment as an example in the figure) can be fixed on the vertical slide grooves on both sides of the box body by the built-in steel cylinder, and the test height can be adjusted by the support cross bar 103.

[0051] See the attached Figure 3 A shield machine 400 has a trapezoidal cross section along the length direction, and has a cutterhead 401 at the front end, a shield tail 402 at the rear end, and a segment 403. The diameter of the cutterhead of the shield machine is the largest, and the diameter of the shield tail is the smallest. The diameters of the cutterhead and the shield tail of the shield machine are both larger than the diameter of the tunnel segment. Half of the difference between the diameter of the cutterhead and the diameter of the shield tail of the shield machine is called an excavation gap 404, that is, the height difference between the cutterhead and the shield tail. Half of the difference between the diameter of the shield tail and the diameter of the segment is called a shield tail gap 405, that is, the height difference between the shield tail and the segment. During the shield excavation process, an excavation gap is first formed, causing ground settlement; as the shield advances, when the shield tail is disengaged, a shield tail gap appears again. At this time, the excavation gap and the shield tail gap together cause ground settlement.

[0052] Combined with Figure 2 , Figure 3 The present invention also provides a simulation test method according to the simulation test platform, comprising the following steps:

[0053] S1: Simulation of shield tunneling starts;

[0054] S2: the excavation gap 404 generated by the discharge of water from the outer ring water layer of the previous ring to simulate the cutterhead excavation;

[0055] S3: After the excavation gap acts for a certain period of time, the water in the inner ring water layer of the previous ring is released to simulate the shield tail coming out and generating the shield tail gap 405;

[0056] S4: After the excavation gap and the shield tail gap work together for a certain period of time, grouting is performed on the outer ring water layer of the previous ring, and different filling degrees are simulated by designing and controlling the grouting amount;

[0057] S5: repeating steps S2-S4, draining and grouting the next ring of water layers that have reached the designed excavation time;

[0058] S6: Repeat step S5, and set the actual time difference between the drainage of the annular water layer and the grouting filling in different rings, and perform simulated excavation in sequence to realize the advancement of the shield.

[0059] The working principle of the present invention is:

[0060] ① Similarity treatment of geological conditions: According to the burial depth, tunnel diameter and soil conditions of the actual engineering survey, the parameters of the simulation experiment are determined according to the appropriate similarity ratio K (the ratio of the actual value on site to the indoor simulation value).

[0061] ② Determination of shield machine working conditions: Calculate the appropriate grouting pressure through the stratum properties simulated by indoor experiments, and set the shield excavation gap value and shield tail gap value in combination with the shield construction parameters.

[0062] ③Equipment construction, single-point displacement meter layout and wiring (one row of original soil and one row of ultra-deep drilled holes artificial backfill soil), and soil filling operations.

[0063] When installing a single-point displacement meter that simulates ultra-deep backfill soil, you can use a PVC pipe as a sleeve to directly cover the single-point displacement meter inside, fill the backfill soil inside, fill the original soil outside, and finally remove the sleeve. You can also use a short cylindrical tube to block and fill it section by section, and then raise the short cylindrical tube while filling. The ultra-deep section in the sleeve is backfilled with soil, and the rest is original soil, simulating different soil layers on site.

[0064] When installing a single-point displacement meter that simulates original soil, no sleeve is needed and the original soil can be directly filled in the entire box layer by layer.

[0065] ④ Excavation simulation. According to the design value, water is first released from the outer annular water layer 203 of different divided rings according to the set time to simulate the shield machine passing through each ring of segments (3 rings are shown in the figure), and the excavation gap caused by the cutter head excavation is simulated. After the excavation gap acts for a certain period of time, water is released from the inner annular water layer 204 to simulate the shield tail gap caused by the cutter head shield tail escaping. At this time, the excavation gap and the shield tail gap work together to cause soil settlement, and grouting is injected into the outer annular water layer 203 through the grouting holes, and the different degrees of filling are simulated by the calculated grouting amount.

[0066] When the annular water layer of the front ring simulated segment is drained and grouting is filled, the annular water layer of the rear ring that has reached the designed excavation time is drained and grouting is filled. Through the actual set time difference of draining the annular water layer and grouting filling of different rings, simulated excavation is carried out in sequence to realize the movement and advancement of the shield, that is, to simulate the movement of the excavation gap, the shield tail gap and the grouting filling.

[0067] ⑤ Collect settlement data of the single-point displacement meter during the simulated shield excavation process.

[0068] Because the settlement of the soil is determined by the excavation gap, the shield tail gap and the filling conditions of the two, the present invention simulates the pipe segment by a fixed built-in steel cylinder, simulates the excavation gap by an outer ring water layer, simulates the shield tail gap by an inner ring water layer, and simulates the filling condition by grouting, and simultaneously uses a single-point displacement meter to monitor the soil settlement and study its law. The simulation test platform of the present invention can achieve the following functions:

[0069] 1. Under different excavation gaps and shield tail gaps, soil settlement data at different depths were collected by using a single-point displacement meter to study the settlement law of soil caused by shield tunnel excavation.

[0070] 2. Under certain conditions of setting the excavation gap and the shield tail gap, the single-point displacement meter is used to collect the soil settlement data at different depths, and the difference in the settlement of the original soil and the ultra-deep backfill soil in the soil layer of the same depth is compared. The correction law of the settlement value monitored by the single-point displacement meter of different ultra-deep boreholes is studied.

[0071] At this point, those skilled in the art should recognize that, although the exemplary embodiments of the present invention have been shown and described in detail herein, many other variations or modifications that conform to the principles of the present invention can still be directly determined or derived based on the contents disclosed in the present invention without departing from the spirit and scope of the present invention. Therefore, the scope of the present invention should be understood and recognized as covering all these other variations or modifications.

Claims

1. A shield excavation and soil settlement monitoring simulation test platform, characterized in that It includes a box, an excavation simulation system and a soil settlement monitoring system, including: The box is filled with undisturbed soil; The excavation simulation system is installed in the box, including a built-in steel cylinder, which serves as the bearing foundation of the excavation simulation system, and a number of annular baffles concentric with the built-in steel cylinder are evenly arranged at intervals on the periphery thereof, and an outer annular water layer and an inner annular water layer concentric with the built-in steel cylinder are installed between adjacent annular baffles, the outer annular water layer is provided with water injection holes and grouting holes connected to the interior thereof, and the inner annular water layer is provided with water injection holes connected to the interior thereof; wherein, the inner annular water layer is used to simulate the outer diameter of the shield machine, and in the simulated excavation stage, water is discharged through the water injection holes of the inner annular water layer to control the thickness of the inner annular water layer to simulate the radius changes of the front shield, middle shield and tail shield of the shield respectively passing through the same ring piece; the outer annular water layer is used to simulate the excavation gap and its filling control during the shield excavation process, and the excavation gap is simulated by draining water through the water injection holes of the outer annular water layer, and the excavation gap filling is simulated through the grouting holes; The soil settlement monitoring system comprises at least one row of single-point displacement meters, and the single-point displacement meters are buried in the original soil.

2. The simulation test platform according to claim 1, characterized in that: The box body adopts a three-dimensional steel plate soil box with an open top, and a vertical slide groove is opened on the left and right side plates of the soil box for placing the two ends of the built-in steel cylinder, so that the built-in steel cylinder can slide up and down in the vertical slide groove, thereby adjusting the layout height of the excavation simulation system.

3. The simulation test platform according to claim 2, characterized in that: The vertical chute is provided with a vertical chute sealing plate for sealing the internal filling.

4. The simulation test platform according to claim 1, characterized in that: The soil settlement monitoring system comprises a first row of single-point displacement meters and a second row of single-point displacement meters. The areas around the first row of single-point displacement meters are backfilled with original soil, and the ultra-deep sections of the holes of the second row of single-point displacement meters are backfilled with test soil.

5. The simulation test platform according to claim 4, characterized in that: The first row of single-point displacement meters and the second row of single-point displacement meters are respectively fixed to the upper part of the box body by single-point displacement meter fixing rods.

6. The simulation test platform according to claim 4, characterized in that: The first row of single-point displacement meters and the second row of single-point displacement meters are respectively provided with a plurality of single-point displacement meters, and the buried depths of the single-point displacement meters are different.

7. The simulation test platform according to claim 1, characterized in that: The spacing distance between the annular partitions is the width of the simulated segments of the shield tunnel.

8. The simulation test platform according to claim 1, characterized in that: Both ends of the built-in steel cylinder of the excavation simulation system are fixed at the test height by supporting cross bars.

9. The simulation test method of the simulation test platform according to any one of claims 1 to 8, characterized in that The steps include: S1: Simulation of shield tunneling starts; S2: the water release from the outer ring water layer of the previous ring simulates the excavation gap caused by the cutterhead excavation; S3: After a certain period of time of excavation gap, water is released from the inner water layer of the previous ring to simulate the shield tail gap caused by the shield tail coming out; S4: After the excavation gap and the shield tail gap work together for a certain period of time, grouting is performed on the outer ring water layer of the previous ring, and different filling degrees are simulated by designing and controlling the grouting amount; S5: repeating steps S2-S4, draining and grouting the next ring of water layers that have reached the designed excavation time; S6: Repeat step S5, and set the actual time difference between the drainage of the annular water layer and the grouting filling in different rings, and perform simulated excavation in sequence to realize the advancement of the shield.

10. The simulation test method according to claim 9, characterized in that: The excavation gap and the shield tail gap are fixed, and the single-point displacement meter is used to collect soil settlement data at different depths. The differences in the single-point displacement meter settlement values ​​of the original soil and the ultra-deep backfill soil in the soil layer of the same depth are compared, and the correction rules of the single-point displacement meter settlement monitoring values ​​of different ultra-deep depths are studied.

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