Tunnel model test excavation disturbance simulation control method

Abstract

This invention relates to the field of tunnel geomechanics technology and discloses a method for simulating and controlling excavation disturbance in tunnel model tests. The method includes: preparing a precast lining model; preparing an internal core block adapted to a set disturbance level, with the outer contour of the internal core block scaled proportionally to the inner contour of the precast lining model; cutting the internal core block into multiple sub-core blocks; embedding the internal core block into the precast lining model, ensuring it fits against the inner wall of the model; embedding the precast lining model and internal core blocks into the surrounding rock; and excavating each sub-core block sequentially according to a set tunnel excavation step, while monitoring the deformation data of the surrounding rock. This invention can simulate the excavation process of a precast tunnel lining model under a set disturbance level, obtain the influence of the excavation disturbance level on the indoor model test of the tunnel lining, realize the simulation of disturbance in the test, and facilitate the application of the precast tunnel lining model to actual engineering projects.

Description

Technical Field

[0001] This invention relates to the field of tunnel geomechanics technology, and in particular to a method for simulating and controlling excavation disturbances in tunnel model tests. Background Technology

[0002] Tunnel engineering structures are an important component of transportation engineering, and my country is currently in a crucial stage where tunnel maintenance and construction are given equal importance. Due to various factors such as hydrogeological conditions, support parameter design, support material selection, and construction quality, defects such as lining cracking, invert heave, and spalling in operating tunnels are becoming increasingly apparent, seriously affecting the tunnel's service performance and lifespan. Simultaneously, phenomena such as structural water leakage and frost damage occur, further exacerbating the deterioration process of the tunnel lining. Therefore, research on tunnel lining is indispensable when studying defects or defects in operating tunnels.

[0003] In tunnel lining mechanical model tests, support methods are divided into two types: manual excavation followed by support and precast embedded support. Manual excavation support suffers from drawbacks such as long cycles, cumbersome procedures, and rough workmanship, as well as significant dimensional errors and low repeatability. For tunnel model tests requiring high precision, it is difficult to meet the diverse needs of simulating actual engineering projects. Therefore, precast lining models are currently commonly used for tunnel model tests. However, current indoor model tests of tunnel lining often struggle to simulate the disturbances caused by tunnel excavation, lacking research on disturbance simulation during testing, which hinders further engineering applications. Summary of the Invention

[0004] The purpose of this invention is to provide a method for simulating and controlling excavation disturbances in tunnel model tests, so as to solve the problem in the prior art that it is difficult to simulate tunnel excavation disturbances when conducting indoor model tests of tunnel lining.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] The tunnel model test excavation disturbance simulation control method of the present invention includes:

[0007] Step S1: Prepare a prefabricated lining model;

[0008] Step S2: According to the set disturbance level, prepare an internal core block that matches the disturbance level. The outer contour of the internal core block is scaled proportionally based on the inner contour of the prefabricated lining model.

[0009] Step S3: Cut the built-in core block according to the set tunnel excavation steps, and divide the built-in core block into multiple sub-core blocks;

[0010] Step S4: The built-in core block is pre-embedded into the prefabricated lining model so that the built-in core block fits against the inner wall of the prefabricated lining model;

[0011] Step S5: Embed the prefabricated lining model and the built-in core block into the surrounding rock;

[0012] Step S6: Excavate each sub-core block sequentially according to the set tunnel excavation steps, and monitor the deformation data of the surrounding rock.

[0013] Preferably, the system further includes a pre-testing step, which includes:

[0014] Using materials of different stiffness as substrates, embedded core blocks that fit into the prefabricated lining model are prepared respectively.

[0015] For the built-in core blocks of various material types, the test process of steps S3-S6 is carried out to obtain the surrounding rock deformation data corresponding to the built-in core blocks of various material types respectively.

[0016] The degree of disturbance is obtained based on the surrounding rock deformation data corresponding to the built-in core blocks of various material types;

[0017] Draw a graph showing the relationship between the degree of disturbance and the types of materials.

[0018] Preferably, the material stiffness of the built-in core of each material type is positively correlated with the degree of disturbance.

[0019] Preferably, in step S2, the step of preparing an embedded core block adapted to the disturbance level includes: determining the material type corresponding to the set disturbance level according to the relationship diagram between the disturbance level and the material type; and preparing the embedded core block by using the determined material type as the preparation material.

[0020] Preferably, the material of the built-in core block is one of rigid foam material, rigid plastic material, or lightweight honeycomb aluminum material.

[0021] Preferably, the degree of disturbance corresponding to the rigid foam material, the degree of disturbance corresponding to the rigid plastic material, and the degree of disturbance corresponding to the lightweight honeycomb aluminum material increases sequentially.

[0022] Preferably, step S3 further includes fixing a traction anchor pad on the side of each sub-core block facing the tunnel entrance, and each traction anchor pad is connected to a traction rope.

[0023] Preferably, in step S3, the cutting surface of the built-in core block is parallel to the horizontal or vertical plane.

[0024] Preferably, the precast lining model is a multi-layer precast lining model.

[0025] Compared with existing technologies, the tunnel model test excavation disturbance simulation control method of this invention has the following advantages:

[0026] The tunnel model test excavation disturbance simulation control method of this invention involves pre-preparing a prefabricated lining model, setting a disturbance level and preparing an internal core block adapted to the disturbance level, cutting the internal core block into multiple sub-core blocks according to the tunnel excavation steps, assembling the prefabricated lining model and the internal core block assembly into the surrounding rock, excavating each sub-core block according to the set tunnel excavation steps, and obtaining the surrounding rock deformation under the disturbance level based on the monitored surrounding rock deformation data, thereby simulating the tunnel prefabricated lining model excavation process under the set disturbance level, obtaining the influence of the excavation disturbance level on the tunnel lining indoor model test, realizing the disturbance simulation in the test, and facilitating the application of the tunnel prefabricated lining model to engineering practice. Attached Figure Description

[0027] Figure 1 This is a flowchart illustrating the tunnel model test excavation disturbance simulation control method according to an embodiment of the present invention;

[0028] Figure 2 This is a schematic diagram of the built-in core block in an embodiment of the present invention;

[0029] Figure 3 This is a simplified mechanical model diagram of the tunnel excavation process in an embodiment of the present invention.

[0030] In the diagram, 1 is the built-in core block; 11 is the sub-core block; 111 is the traction anchor pad; 2 is the prefabricated lining model; and 3 is the surrounding rock. Detailed Implementation

[0031] In the description of this invention, it should be noted that the terms "center," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0032] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0033] Please see Figures 1-3An embodiment of the present invention provides a method for simulating and controlling excavation disturbance in a tunnel model test, comprising the following steps: S1, preparing a prefabricated lining model 2; S2, preparing an internal core block 1 adapted to a set disturbance level, wherein the outer contour of the internal core block 1 is scaled proportionally based on the inner contour of the prefabricated lining model 2, and the set disturbance level is the disturbance level to be simulated; S3, cutting the internal core block 1 according to a set tunnel excavation step, dividing the internal core block 1 into multiple sub-core blocks 11; S4, pre-embedding the internal core block 1 into the prefabricated lining model 2, so that the internal core block 1 fits against the inner wall of the prefabricated lining model 2; S5, pre-embedding the prefabricated lining model 2 and the internal core block 1 into the surrounding rock 3; and S6, excavating each sub-core block 11 sequentially according to the set tunnel excavation step, and monitoring the deformation data of the surrounding rock 3.

[0034] By pre-preparing a prefabricated lining model 2, setting a disturbance level, and preparing an internal core block 1 adapted to this disturbance level, the internal core block 1 is cut into multiple sub-core blocks 11 according to the tunnel excavation steps. The prefabricated lining model 2 and the internal core block 1 are then assembled into the surrounding rock 3. Each sub-core block 11 is excavated according to the set tunnel excavation steps. Based on the monitored deformation data of the surrounding rock 3, the deformation of the surrounding rock 3 under this disturbance level can be determined, thereby simulating the excavation process of the prefabricated tunnel lining model 2 under the set disturbance level. This allows for the simulation of disturbance levels on the tunnel lining indoor model test, facilitating the application of the prefabricated tunnel lining model 2 to actual engineering projects. Furthermore, this invention can achieve active control of excavation disturbance to varying degrees during the test. It is also simple in construction, energy-saving and environmentally friendly, and easy to disassemble and reuse, possessing high feasibility, economic value, and promotional potential.

[0035] In step S1, the precast lining model 2 is a multi-layer precast lining model 2. In some embodiments, the precast lining model 2 is a three-layer precast lining model 2. The steps for preparing the precast lining model 2 include:

[0036] Step S11: According to the requirements of the mechanical tunnel model test, the three-layer tunnel lining model is scaled up proportionally. Based on the scaled dimensions, a waterjet cutting machine is used to position and cut the upper top plate, lower bottom plate, inner forming mold, and three outer forming molds. Note that the lower bottom plate only needs to have a few fixing column holes, while the upper top plate needs to have fixing column holes and a concentric arc discharge port for lining pouring. The upper top plate and lower bottom plate are made of transparent acrylic sheets. The outer forming mold and inner forming mold are made of rigid foam material.

[0037] Step S12: Apply lubricant to the tunnel lining forming surface of the tunnel lining mold to facilitate demolding and reduce mold wear;

[0038] Step S13: Insert the fixing post into the corresponding hole in the bottom plate and install the fixing cap;

[0039] Step S14: Insert the fixing column corresponding to the outer mold, install the top plate and fixing hole cap, so that the prefabricated device is fixed as one piece;

[0040] Step S15: According to the tunnel lining performance requirements studied, and based on the similar material ratio, a certain mix ratio of lining material is stirred and mixed evenly, and then poured into the three-layer lining prefabricated cavity through the upper top plate discharge port, and left to stand for a period of time to form.

[0041] Step S16: Remove the top plate, inner mold, outer mold and fixed column layer by layer to obtain three-layer prefabricated lining model 2.

[0042] Optionally, when conducting tunnel model tests on the prefabricated lining model 2, if the required tunnel lining structure consists of multiple sections, the operation process of steps S11-S16 is repeated until the required number and length for the test are met.

[0043] In some embodiments, the tunnel model test excavation disturbance simulation control method further includes a pre-test step, which includes:

[0044] Using materials of different stiffness as base materials, embedded core blocks 1 that fit into the prefabricated lining model 2 are prepared respectively. The outer contour dimensions of the embedded core block 1 can be obtained by scaling the inner contour of the prefabricated lining model 2 proportionally, so that the embedded core block 1 fits into the prefabricated lining model 2, which facilitates the assembly of the embedded core block 1 and the prefabricated lining model 2. Different materials have different stiffnesses, so embedded core blocks 1 with different stiffnesses can be obtained.

[0045] For each type of built-in core block 1, the test process of steps S3-S6 is carried out to obtain the deformation data of the surrounding rock 3 corresponding to each type of built-in core block 1. The deformation data of the surrounding rock 3 includes parameters such as stress, strain and displacement of the surrounding rock 3.

[0046] The degree of disturbance is obtained based on the deformation data of the surrounding rock 3 corresponding to the built-in core block 1 of each material type;

[0047] A graph showing the relationship between the degree of disturbance and the type of material was drawn to facilitate the selection of the material of the built-in core block 1 based on the degree of disturbance required for the experiment, thereby making it easier to obtain the influence of the degree of disturbance on tunnel excavation.

[0048] The relationship between the degree of disturbance and the type of material is plotted with the material's elastic modulus on the horizontal axis and the degree of disturbance on the vertical axis.

[0049] In step S2, the step of preparing the built-in core block 1 adapted to the disturbance level includes: determining the material type corresponding to the set disturbance level according to the relationship diagram between the disturbance level and the material type; using the determined material type as the preparation material for the built-in core block 1, and preparing the built-in core block 1. The disturbance level of the prepared built-in core block 1 is then determined. This disturbance level is used as a known parameter, and subsequent steps S3-S6 are used to obtain the tunnel excavation simulation process under this disturbance level, thus obtaining the influence of this disturbance level on tunnel excavation. It should be noted that any disturbance level fluctuating within a certain range above and below the disturbance level corresponding to a certain material type can be considered as the disturbance level corresponding to that material type.

[0050] Using a defined material type as the material for preparing the built-in core block 1, a waterjet engraving machine is used to cut the built-in core block 1 so that the outer contour of the prepared built-in core block 1 is scaled proportionally based on the inner contour of the prefabricated lining model 2.

[0051] The material stiffness of the built-in core 1 of each material type is positively correlated with the degree of disturbance, and this is verified by calculation in the following way:

[0052] For details, please refer to Figure 3 The two-dimensional simplified mechanical model shown divides the tunnel along its length into three stages: the first stage, the second stage, and the third stage. The first stage is closest to the tunnel entrance, while the third stage is furthest from the tunnel entrance.

[0053] In the mechanical equilibrium system of the surrounding rock 3 and the support before the excavation of the model tunnel (i.e., the third stage), the geological stress is P0 and the supporting force of the surrounding rock 3 is P. S The reaction force P of the support structure C And P0, P S P C The following relationship must be satisfied:

[0054] P0 = P S +P C (1)

[0055] Since the support structure is composed of multiple layers of lining and an internal core block 1, the supporting reaction force P of the support structure can be calculated using the following formula. C :

[0056] P C =P L +P R (2)

[0057] In the formula: P L For the reaction force of the multi-layer lining structure; P R The reaction force is for the built-in core block 1;

[0058] Combining formulas (1) and (2), we can obtain the following formula (3):

[0059] P0 = P S +P L +P R (3)

[0060] During tunnel excavation (i.e., the second stage), the overall structural mechanical equilibrium is disrupted, and the supporting force provided by the built-in core block 1 is reduced by P. R Change to P R ′ The supporting force provided by the built-in core block 1 gradually decreases as the excavation progresses, and the equation in formula (3) is transformed into the following formula (4):

[0061] P0>P S +P L +P R ′ (4)

[0062] Furthermore, due to the rheological properties of soft rock, tunnel excavation caused a stress redistribution in the surrounding rock 3, resulting in a change in the supporting force of the surrounding rock 3 from P. S Increase to P S ′ Therefore, the supporting reaction force P of the support structure C ′ This means that the contact pressure between the surrounding rock 3 and the support structure decreases. After the model tunnel excavation is completed (first stage), the convergence deformation of the surrounding rock 3 increases rapidly, while the supporting reaction force P of the support structure... C ′ Only composed of multi-layer lining structure P L ′ As a result, the contact pressure increases dramatically, leading to a new equation:

[0063] P0 = P S ′ +P C ′ (5)

[0064] From formulas (1) to (5), it can be deduced that the stiffness of the embedded core block 1 in the pre-embedded lining model is positively correlated with the degree of disturbance during tunnel excavation. The greater the material stiffness of the embedded core block 1, the stronger the degree of disturbance during tunnel excavation in the model.

[0065] Please see Figure 3In some embodiments, the material of the built-in core block 1 is one of rigid foam, rigid plastic, or lightweight honeycomb aluminum. The disturbance level corresponding to the rigid foam material, the rigid plastic material, and the lightweight honeycomb aluminum increases sequentially. The disturbance level corresponding to the rigid foam material is approximately 12%, and any disturbance level fluctuating within the range of 12% can be considered as corresponding to the rigid foam material. For example, when the disturbance level is 10%, 11%, 13%, or 14%, the material of the built-in core block 1 can be selected as rigid foam. The disturbance level corresponding to the rigid plastic material is approximately 21%, and the disturbance level corresponding to the lightweight honeycomb aluminum material is approximately 37%. Optionally, the disturbance level can be divided into low disturbance level, medium disturbance level, and high disturbance level according to a certain range. The disturbance level corresponding to the rigid foam material is low disturbance level, the disturbance level corresponding to the rigid plastic material is medium disturbance level, and the disturbance level corresponding to the lightweight honeycomb aluminum material is high disturbance level. Based on this, the entire disturbance level range can be covered by three material types to realize the excavation simulation of different disturbance level ranges, and the material type of the built-in core block 1 corresponding to different disturbance level ranges can be selected.

[0066] In some embodiments, step S3 further includes: fixing traction anchor pads 111 to the side of each sub-core block 11 facing the tunnel entrance, and connecting each traction anchor pad 111 to a traction rope. The traction rope is used to pull the sub-core block 11 out of the tunnel to simulate tunnel excavation. The traction anchor pads 111 are bonded and fixed to the built-in core block 1, and the traction rope can be a steel wire.

[0067] In some embodiments, in step S3, a waterjet cutting machine is used to cut the built-in core block 1. The cut surface of the built-in core block 1 is parallel to the horizontal or vertical plane to facilitate the simulation of the tunnel excavation process.

[0068] In step S5, when the test filling reaches the tunnel elevation, the precast lining model 2 and the built-in core block 1 are pre-embedded in the surrounding rock 3, and the joint is treated before subsequent filling, excavation, loading, data monitoring and other processes are carried out.

[0069] It should be noted that the tunnel excavation steps set in step S6 are tunnel excavation steps that conform to actual construction specifications, for reference. Figure 3 In the middle, the excavation order of each sub-core block 11 is abcd.

[0070] In summary, this invention provides a method for simulating and controlling excavation disturbance in a tunnel model test. It involves pre-preparing a prefabricated lining model 2, setting a disturbance level, and preparing an internal core block 1 adapted to that disturbance level. The internal core block 1 is then cut into multiple sub-core blocks 11 according to the tunnel excavation steps. The prefabricated lining model 2 and the internal core block 1 are then assembled into the surrounding rock 3. Each sub-core block 11 is excavated according to the set tunnel excavation steps. Based on the monitored deformation data of the surrounding rock 3, the deformation of the surrounding rock 3 under the disturbance level can be determined, thereby simulating the excavation process of the prefabricated lining model 2 under the set disturbance level. This method obtains the influence of the excavation disturbance level on the tunnel lining indoor model test, achieving disturbance simulation in the test and facilitating the application of the prefabricated lining model 2 to actual engineering projects.

[0071] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention.

Claims

1. A tunnel model test excavation disturbance simulation control method, characterized in that, include: Step S1: Prepare a prefabricated lining model; Step S2: According to the set disturbance level, prepare an internal core block that matches the disturbance level. The outer contour of the internal core block is scaled proportionally based on the inner contour of the prefabricated lining model. Step S3: Cut the built-in core block according to the set tunnel excavation steps, and divide the built-in core block into multiple sub-core blocks; Step S4: The built-in core block is pre-embedded into the prefabricated lining model so that the built-in core block fits against the inner wall of the prefabricated lining model; Step S5: Embed the prefabricated lining model and the built-in core block into the surrounding rock; Step S6: Excavate each sub-core block sequentially according to the set tunnel excavation steps, and monitor the deformation data of the surrounding rock; It also includes a pre-testing step, which includes: Using materials of different stiffness as substrates, embedded core blocks that fit into the prefabricated lining model are prepared respectively; For the built-in core blocks of various material types, the test process of steps S3-S6 is carried out to obtain the surrounding rock deformation data corresponding to the built-in core blocks of various material types respectively. The degree of disturbance is obtained based on the surrounding rock deformation data corresponding to the built-in core blocks of various material types; Draw a graph showing the relationship between the degree of disturbance and the types of materials; In step S2, the step of preparing an embedded core block adapted to the disturbance level includes: determining the material type corresponding to the set disturbance level according to the relationship diagram between the disturbance level and the material type; and preparing the embedded core block by using the determined material type as the preparation material.

2. The tunnel model test excavation disturbance simulation control method according to claim 1, characterized in that, The material stiffness of the built-in core of each material type is positively correlated with the degree of disturbance.

3. The tunnel model test excavation disturbance simulation control method according to claim 1, characterized in that, The material of the built-in core block is one of rigid foam, rigid plastic, or lightweight honeycomb aluminum.

4. The tunnel model test excavation disturbance simulation control method according to claim 3, characterized in that, The degree of disturbance corresponding to the rigid foam material, the degree of disturbance corresponding to the rigid plastic material, and the degree of disturbance corresponding to the lightweight honeycomb aluminum material increases sequentially.

5. The method for simulating and controlling excavation disturbance in tunnel model tests according to claim 1, characterized in that, Step S3 further includes fixing a traction anchor pad on the side of each sub-core block facing the tunnel entrance, and each traction anchor pad is connected to a traction rope.

6. The method for simulating and controlling excavation disturbance in tunnel model tests according to claim 1, characterized in that, In step S3, the cutting surface of the built-in core block is parallel to the horizontal or vertical plane.

7. The method for simulating and controlling excavation disturbance in tunnel model tests according to claim 1, characterized in that, The precast lining model is a multi-layer precast lining model.

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