Testing device and method for simulating slurry buoyancy of segments under different burial depth conditions

Abstract

The present invention belongs to the technical field of test devices, and proposes a test device and method for simulating the buoyancy of slurry on a pipe segment under different burial depth conditions, comprising: a box body, a slurry containing device is provided inside, and a grouting hole is provided on the slurry containing device; a pipe segment model is arranged in the slurry containing device; a tension sensor, one end of which is fixed on the inner wall of the box body, and the other end is fixed on the outer wall of the pipe segment model; when the pipe segment model is placed in the slurry containing device and grouting is performed through the grouting hole on the slurry containing device, the buoyancy of the pipe segment is tested by the tension sensor with one end fixed on the inner wall of the box body and the other end fixed on the outer wall of the pipe segment model. Compared with the existing device, the buoyancy is converted into tension for testing, thereby avoiding the use of a reaction frame and the like, and avoiding the influence of deformation of the reaction frame and the like caused by excessive pressure. On the one hand, the accuracy of data collection is improved, and on the other hand, the test cost is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of test devices, and in particular relates to a test device and method for simulating the buoyancy of slurry on a pipe segment under conditions of different burial depths. Background Art

[0002] With the increasing popularity of shield tunneling technology, more and more large-diameter shield tunnels have emerged, and their construction has also faced severe challenges. After synchronous grouting, due to the high density of the grouting slurry and the time it takes to solidify, the buoyancy of the segments in the slurry is far greater than their own weight, which provides the segments with upward buoyancy. To meet normal construction requirements, the diameter of the excavated section is often slightly larger than the outer diameter of the segment, known as the shield tail gap, which provides space for the segments to float upward. During the construction of large-diameter shield tunnels, the construction risks caused by the floating segments, such as segment misalignment, pipe seam leakage, and axis deviation, are becoming increasingly significant. If these issues are not addressed, they will seriously endanger construction safety.

[0003] Currently, the primary approach to addressing this issue involves filling the tunnel with heavy objects and adding shear pins to improve the tunnel's anti-buoyancy capabilities. However, the mechanism of slurry buoyancy variations on the segments in the slurry remains unclear and under investigation. The lack of accurate guidance on slurry buoyancy variations often leads to overcorrection in these anti-buoyancy measures, negatively impacting the tunnel's overall stiffness and increasing construction costs. Therefore, accurately measuring slurry buoyancy variations at varying burial depths is an urgent need.

[0004] The inventors have found that the current research devices on slurry buoyancy have the following main deficiencies: existing test devices usually convert the buoyancy of the segment model into pressure, and indirectly measure the buoyancy of the segment model. Since the pressure sensor is fixed on the reaction frame, when the segment model is large, the slurry buoyancy it is subjected to also increases exponentially, which will cause the crossbeam fixing the pressure sensor to produce a large deformation, affecting the data acquisition accuracy and increasing the test cost; due to the influence of soil arch effect and slurry penetration, the interaction mechanism between the overburden pressure and the segment is still unclear; due to the lack of relevant research, theoretical calculations usually simplify the overburden pressure to act directly on the segment, which cannot reflect the actual stress state of the segment; the existing device does not realize the slurry outflow simulation diffusion process. Summary of the Invention

[0005] In order to solve the above problems, the present invention proposes a testing device and method for simulating the buoyancy of slurry on pipe segments under different burial depth conditions, which can obtain the change law of longitudinal resultant force over time.

[0006] To achieve the above objectives, in a first aspect, the present invention provides a testing device for simulating the buoyancy of slurry on segments under different burial depths, which adopts the following technical solutions:

[0007] A testing device for simulating the buoyancy of slurry on segments under different burial depths, comprising:

[0008] The box body is provided with a slurry containing device inside, and the slurry containing device is provided with a grouting hole;

[0009] The segment model is placed in the slurry holding device;

[0010] A tension sensor has one end fixed on the inner wall of the box and the other end fixed on the outer wall of the segment model.

[0011] Furthermore, the slurry holding device is a rubber bag, and a plurality of hollow tubes are further provided in the box body, one end of the hollow tube is in contact with the rubber bag, and the other end extends to the outside of the box body.

[0012] Furthermore, a filler is provided between the box body and the slurry containing device.

[0013] Furthermore, the slurry holding device is provided with an exhaust hole, and the exhaust hole is connected to a pressure maintaining system through a pipeline.

[0014] Furthermore, the grouting holes are connected to a grouting system via pipelines.

[0015] Furthermore, there are multiple tension sensors, which are arranged at the lower end of the segment model; and the tension sensors are connected to a collector.

[0016] Furthermore, the segment model is a tubular object with both ends closed.

[0017] To achieve the above-mentioned purpose, in a second aspect, the present invention further provides a method for testing the buoyancy of slurry on segments under conditions of simulating different burial depths, using the following technical solutions:

[0018] A testing method for simulating the buoyancy of slurry on a segment under different burial depths, using the testing device for simulating the buoyancy of slurry on a segment under different burial depths as described in the first aspect, comprising:

[0019] injecting grout into the slurry containing device through the grouting hole;

[0020] The slurry buoyancy force on the segment model is tested by a tension sensor;

[0021] The slurry buoyancy acting on the segment model under different burial depths is obtained from the equilibrium equation.

[0022] Furthermore, a thin rod with a pointed end was inserted into the hollow tube to destroy the rubber capsule, simulating the slurry diffusion process.

[0023] Furthermore, air pressure is applied to the slurry holding device through the pressure maintaining system to simulate the state of the segment just after being dragged out of the shield tail during the construction process.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. In the present invention, the segment model is placed in a slurry containing device. When grouting is performed through the grouting holes on the slurry containing device, the buoyancy of the segment caused by the slurry is tested by a tension sensor with one end fixed to the inner wall of the box and the other end fixed to the outer wall of the segment model. Compared with the existing device, the buoyancy is converted into tension for testing, which avoids the use of reaction frames and the like, and avoids the influence of deformation of the reaction frames and the like due to excessive pressure. On the one hand, the accuracy of data collection is improved, and on the other hand, the test cost is reduced.

[0026] 2. In the present invention, the slurry holding device is set as a rubber bag, and multiple hollow tubes with one end in contact with the rubber bag are set in the box. During the test, a thin rod with a pointed end is inserted into the hollow tube to destroy the rubber bag, thereby simulating the slurry diffusion process.

[0027] 3. In the present invention, the slurry holding device is connected to the pressure maintaining system through the exhaust hole, and air pressure is applied to the slurry holding device through the pressure maintaining system, thereby simulating the state of the pipe segment just after being dragged out of the shield tail during the construction process. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The drawings constituting a part of the specification of this embodiment are used to provide a further understanding of this embodiment. The schematic embodiments and descriptions of this embodiment are used to explain this embodiment and do not constitute an improper limitation on this embodiment.

[0029] Figure 1 This is a schematic structural diagram of Example 1 of the present invention;

[0030] Figure 2 For Example 1 of the present invention Figure 1 Side view of;

[0031] Figure 3 Schematic diagram of a hollow tube according to Example 1 of the present invention;

[0032] Figure 4 This is a force diagram of the pipe segment of Example 1 of the present invention;

[0033] Among them, 1. Box body; 2. Exhaust hole; 3. Grouting hole; 4. Pressure maintaining system; 5. Grouting system; 6. Hollow pipe; 7. Slurry holding device; 8. Segment model; 9. Tension sensor; 10. Collector; 11. Computer. DETAILED DESCRIPTION

[0034] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0035] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present application belongs.

[0036] Example 1:

[0037] like Figure 1 As shown, this embodiment provides a test device for simulating the buoyancy of slurry on a segment under different burial depths, which mainly includes a box 1, an exhaust hole 2, a grouting hole 3, a grouting system, a pressure maintaining system 4, a grouting system 5, a hollow pipe 6, a slurry holding device 7, a segment model 8, a tension sensor 9, a data acquisition device 10, and a computer 11.

[0038] The slurry receiving device 7 is provided inside the box 1, and the slurry receiving device 7 is provided with a grouting hole 3; it can be understood that the box is mainly used to hold slurry and soil, and can be composed of a plurality of waterproof boards, which enclose a cavity with a certain receiving space;

[0039] The segment model is placed in the slurry holding device;

[0040] A tension sensor has one end fixed on the inner wall of the box and the other end fixed on the outer wall of the segment model.

[0041] In this embodiment, the slurry holding device 7 can be a rubber bag. In other embodiments, the slurry holding device 7 can be a bag-like object made of other materials. A plurality of hollow tubes 6 are also provided in the box body 1. One end of the hollow tube 6 is in contact with the rubber bag, and the other end extends to the outside of the box body 1. The hollow tube 6 is a membrane-breaking tube with a hollow tubular structure. A thin rod with a pointed end can be inserted into the membrane-breaking tube from the outside to destroy the rubber bag. It can be used to simulate the slurry diffusion process after the synchronous grouting process is completed.

[0042] A filler is provided between the box body 1 and the slurry holding device 7, and the filler can be understood as soil.

[0043] An exhaust hole 2 is provided on the slurry holding device 7, and the exhaust hole 2 is connected to the pressure maintaining system 4 through a pipe, and the pipe here is an exhaust pipe; the grouting hole 3 is connected to the grouting system 5 through a pipe, and the pipe here is a grouting pipe; the grouting pipe, the grouting system 5, the exhaust pipe and the pressure maintaining system 4 can be used to simulate the synchronous grouting process in the actual construction process.

[0044] There are multiple tension sensors 9, evenly arranged at the lower end of the segment model 8; the tension sensors 9 are connected to a data acquisition instrument 10, which is connected to a computer 11; specifically, the tension sensors 9, the data acquisition instrument 10, and the computer 11 can be used to measure and derive the magnitude of the force applied to the segment during the test; to ensure the stability of the segment model 8 during the test, six groups of tension sensors 9 can be used to measure the magnitude of the force applied to the segment model 8. The range of the tension sensors 9 should be selected based on the actual test situation. It is recommended that the range of a single sensor be selected as ρ 浆液 πR 2 g / 6 can meet the requirements.

[0045] The ratio λ of the initial slurry buoyancy force on the segment to the segment’s own gravity is:

[0046]

[0047] Where, ρ 浆液 is the slurry density; ρ 管片 is the segment density; R is the segment outer diameter; r is the segment inner diameter; λ parameter, the range can be set between 4 and 5.

[0048] The force diagram of the segment model during the test can be obtained from Figure 4 The equilibrium equation can be expressed as follows:

[0049] F1=F2+F3+G

[0050] Where F1 is the buoyancy of the slurry; F2 is the tension applied to the tension sensor; F3 is the overlying soil pressure; and G is the deadweight of the segment model.

[0051] The measuring range of the tension sensor 9 can be selected according to different test conditions; from the force analysis, it can be seen that the sum of the readings of multiple groups of tension sensors 9 and the deadweight of the segment model 8 is the size of the slurry buoyancy of the segment model under different times and different burial depths; Vaseline can be applied around the tension sensor 9 to reduce the influence of the friction of the soil or slurry around it; it can be understood that a mounting hole for installing the tension sensor 9 is reserved on the slurry containing device 7, and the tension sensor 9 is subjected to conventional sealing treatment after passing through the mounting hole, such as the diameter of the mounting hole is smaller than the diameter of the corresponding position of the tension sensor 9, so that the slurry is prevented from flowing out of the mounting hole without affecting the operation of the tension sensor 9.

[0052] The collector 10 can be used to collect the data size of the tension sensor 9, transmit it to the computer 11, and finally derive the force data of the tension sensor 9 during the test through the computer 11; the data collection continuity can be improved by increasing the collection frequency of the collector 10.

[0053] The segment model 8 is a tubular object with both ends closed. Specifically, the segment model 8 is used to simulate a real segment and is sealed at both ends. To ensure the accuracy of the test results, the segment model 8 must have a high degree of sealing. To ensure smooth test data acquisition, that is, the tension sensor 9 is always subjected to the tension of the segment model 8, the segment model 8 should not be too heavy. Existing studies have shown that in slurry, the slurry buoyancy force on the segment model 8 is equal to the weight of the same volume of slurry discharged. At the same time, considering the influence of the overburden pressure, the segment model 8 should be much smaller than the initial slurry buoyancy force. Therefore, the segment model 8 can be made of a material with a lower density, such as a material with a density much lower than the density of the injected slurry. To ensure normal data acquisition, the segment model 8 should be lightly weighted, preferably 1 / 6 to 1 / 5 of the weight of the same volume of slurry.

[0054] The working process or principle of this embodiment is as follows:

[0055] The box 1 can be mainly used to hold slurry and soil; first, the film-breaking tubes are placed in advance on both sides and the upper part of the box 1 to facilitate the simulation of the subsequent slurry diffusion process; secondly, one end of the force sensor 9 is fixed to the bottom of the box 1; finally, a certain height of soil is pre-filled into the box 1 to simulate the excavation of the lower half of the stratum.

[0056] The segment model 8 should be placed in the slurry holding device 7 before the test; the volume of the slurry holding device 7 after it is fully filled is slightly larger than the volume of the segment model 8, which can be used to simulate the shield tail gap; the slurry holding device 7 can be provided with reserved holes for exhaust pipes and grouting pipes in advance to facilitate the simulation of subsequent pressurization and grouting processes; after connecting the reserved holes with the exhaust pipes, the segment model 8 wrapped by the slurry holding device 7 is placed on the pre-fill soil.

[0057] One end of the tension sensor 9 is fixedly connected to the outer wall of the segment model 8; to ensure the stability of the segment model 8 during the test, a total of 6 groups of tension sensors 9 can be set at the bottom of the segment model 8; to reduce the influence of the friction generated by the soil or slurry around the tension sensor 9, lubricant can be applied around the tension sensor 9.

[0058] The slurry holding device 7 is pressurized by the pressure maintaining system 4 to simulate the construction step of the pipe segment just being dragged out of the shield tail during the actual construction process; the pressure level is consistent with the overburden pressure. For example, if the overburden weight is preset to γ ​​and the burial depth is h, the pressure level should be γh.

[0059] Fill the box 1 with soil to the test design height. In order to eliminate the influence of the above steps on the tension sensor 9, the reading of the tension sensor 9 needs to be reset to zero before the test.

[0060] Slurry is injected into the slurry holding device 7 through the grouting system 5, and the pressure maintaining system 4 is closed at the same time; the grouting pressure can be read by a pressure gauge, and grouting is stopped when the slurry completely fills the slurry holding device 7; slurry is injected into the slurry holding device 7 through the grouting system 5 to simulate the grouting stage in an actual project; during the test, the grouting pressure can also be adjusted to study the influence of the grouting pressure on the stress of the pipe segment model 8.

[0061] The slurry holding device 7 is a rubber bag. An iron pipe with a tip or a rod with a tip is inserted into the pre-buried membrane-breaking tube to destroy the rubber bag, so that the slurry flows out to simulate the diffusion process. In order to facilitate the membrane-breaking tube to destroy the rubber bag, the thickness of the rubber bag should not be too thick.

[0062] After the segment model 8 stabilizes, the data acquisition instrument 10 continuously collects the readings of the six tension sensors 9 during the test. After the test is completed, the collected data is exported using the computer 11. The equilibrium equation shows that the sum of the readings of the six tension sensors 9 and the deadweight of the segment model is the slurry buoyancy acting on the segment at that burial depth. By comparing the slurry buoyancy at different times, the temporal variation of slurry buoyancy at different burial depths can be determined.

[0063] In traditional testing devices, the buoyancy is converted into pressure, and the pressure exerted during the test is measured by fixing a sensor on a reaction frame, thereby indirectly measuring the buoyancy of the slurry on the segment model. This idea is feasible in theory, but in actual operation, the buoyancy of the segment will cause the beam to bend and deform. This phenomenon will be more obvious when the segment model is large, which will significantly affect the accuracy of slurry data acquisition. The idea in this embodiment is to convert buoyancy into tension, so that there is no need for the reaction frame to have a high bending stiffness, nor is there any need to consider the deformation of the reaction frame due to excessive pressure. On the one hand, it can improve the accuracy of data acquisition, and on the other hand, it can reduce the test cost.

[0064] Example 2:

[0065] This embodiment provides a test method for simulating the buoyancy of slurry on a segment under different burial depths, using the test device for simulating the buoyancy of slurry on a segment under different burial depths as described in Example 1, including:

[0066] Inject grout into the slurry holding device 7 through the grouting hole 3;

[0067] The slurry buoyancy force on the segment model 8 is tested by the tension sensor 9;

[0068] The slurry buoyancy acting on the segment model under different burial depths is obtained from the equilibrium equation.

[0069] A thin rod with a pointed end is inserted into the hollow tube 6 to destroy the rubber capsule, simulating the slurry diffusion process.

[0070] Air pressure is applied to the slurry holding device 7 through the pressure maintaining system 4 to simulate the state of the segment just after being dragged out of the shield tail during the construction process.

[0071] The above description is merely a preferred embodiment of this embodiment and is not intended to limit this embodiment. Those skilled in the art will readily appreciate that this embodiment may be modified and varied in various ways. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this embodiment shall be within the scope of protection of this embodiment.

Claims

1. A testing device for simulating the buoyancy of slurry on segments under different burial depths, characterized in that: include: The box body is provided with a slurry containing device inside, and the slurry containing device is provided with a grouting hole; The segment model is placed in the slurry holding device; a tension sensor, one end of which is fixed on the inner wall of the box, and the other end of which is fixed on the outer wall of the segment model; The slurry holding device is a rubber bag, and a plurality of hollow tubes are further provided in the box body, one end of the hollow tube is in contact with the rubber bag, and the other end extends to the outside of the box body; There are multiple tension sensors, which are arranged at the lower end of the segment model; the tension sensors are connected to a data acquisition instrument; The hollow tube is a membrane-breaking tube with a hollow tubular structure. A thin rod with a pointed end is inserted into the membrane-breaking tube from the outside to destroy the rubber bag, so as to simulate the slurry diffusion process after the synchronous grouting process is completed.

2. The testing device for simulating the buoyancy of slurry on segments under different burial depths according to claim 1, characterized in that: A filler is provided between the box body and the slurry containing device.

3. The testing device for simulating the buoyancy of slurry on segments under different burial depths according to claim 1, characterized in that: The slurry containing device is provided with an exhaust hole, and the exhaust hole is connected to a pressure maintaining system through a pipeline.

4. The testing device for simulating the buoyancy of slurry on segments under different burial depths according to claim 1, characterized in that: The grouting holes are connected to a grouting system via pipelines.

5. The testing device for simulating the buoyancy of slurry on segments under different burial depths according to claim 1, characterized in that: The segment model is a tubular object with both ends closed.

6. A test method for simulating the buoyancy of slurry on segments under different burial depth conditions, characterized in that: A test device for simulating the buoyancy of slurry on a segment under different burial depths according to any one of claims 1 to 5 is used, comprising: injecting grout into the slurry containing device through the grouting hole; The slurry buoyancy force on the segment model is tested by a tension sensor; The slurry buoyancy acting on the segment model under different burial depths is obtained from the equilibrium equation.

7. The method for testing a segment under different burial depths by simulating slurry buoyancy as claimed in claim 6, characterized in that: A thin rod with a pointed tip is inserted into the hollow tube to destroy the rubber capsule, simulating the slurry diffusion process.

8. The method for testing a segment under different burial depths by simulating slurry buoyancy as claimed in claim 6, characterized in that: Air pressure is applied to the slurry holding device through the pressure maintaining system to simulate the state of the segment just after being dragged out of the shield tail during construction.

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