Shield tunnel excavation simulation test device and method based on plane strain mode

Abstract

The present invention provides a shield tunnel excavation simulation test device and method based on a plane strain mode, which relates to the technical field of tunnel model test, including building a model box according to a preset design scheme, and sequentially sleeve supporting steel cylinders, model segments, multi-layer prefabricated layers and stainless steel sheets from the inside to the outside to obtain an assembly; filling the model box with a model soil sample, installing the assembly and a micro-soil pressure box in the model box, installing a displacement meter on the upper surface of the model soil sample, and installing a camera outside the model soil sample; leaving the model soil sample still until the model soil sample is fully consolidated, taking out the supporting steel cylinder of the assembly, and after the indications of the micro-soil pressure box and the displacement meter no longer change, extracting the arc prefabricated sheet in a preset order, and recording the changes of the model soil sample during the extraction process through the micro-soil pressure box, the displacement meter and the camera. The present invention realizes the visualization research of the stratum displacement field and the quantitative control of the stratum deformation.

Description

Technical Field

[0001] The present invention relates to the technical field of tunnel model testing, and in particular to a shield tunnel excavation simulation test device and method based on a plane strain mode. Background Art

[0002] In recent years, shield construction has been widely used in highway tunnels, railway tunnels, hydraulic tunnels, urban subways, etc. The deformation and damage of shield tunnels during construction is a very complex process. At present, mathematical mechanics methods can only provide analytical solutions for some tunnel projects with simple shapes and simplified boundary conditions, and the analytical solutions obtained still cannot be separated from the verification of field measured data and model tests.

[0003] Existing indoor model test devices are generally small in size, making it difficult to truly restore the changes in the stress and displacement fields of the strata around the tunnel, unable to realize a visual study of the stratum displacement field, and unable to achieve quantitative control of stratum deformation during simulated tunnel excavation.

[0004] Therefore, there is an urgent need for a shield tunnel excavation simulation test device and method based on a plane strain mode for visualizing the stratum displacement field and simulating the quantitative control of stratum deformation during tunnel excavation. Summary of the invention

[0005] The purpose of the present invention is to provide a shield tunnel excavation simulation test device and method based on plane strain mode to solve the above problems. In order to achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] The present application provides a shield tunnel excavation simulation test method based on a plane strain mode, comprising: building a model box according to a preset design scheme, and sequentially sleeve supporting steel cylinders, model segments, multiple prefabricated layers and stainless steel sheets from the inside to the outside to obtain an assembly, wherein each prefabricated layer is composed of an even number of arc-shaped prefabricated sheets of the same shape and size; filling the model box with a model soil sample, installing an assembly and a micro-soil pressure box in the model box, installing a displacement meter on the upper surface of the model soil sample, and installing a camera on the outside of the model soil sample; leaving the model soil sample still until the model soil sample is fully consolidated, taking out the supporting steel cylinder of the assembly, and after the indications of the micro-soil pressure box and the displacement meter no longer change, pulling out the arc-shaped prefabricated sheets in a preset order, and recording the changes of the model soil sample during the pulling process by means of the micro-soil pressure box, the displacement meter and the camera.

[0007] Optionally, a model box is constructed according to a preset design scheme, including:

[0008] The model box body is constructed by using rigid materials; front tempered glass and rear tempered glass are respectively installed on the front and rear of the model box body, and the front tempered glass and rear tempered glass are respectively provided with a first circular hole and a second circular hole at the same horizontal position; polytetrafluoroethylene film is applied to the inner wall of the model box and the surfaces of the front tempered glass and the rear tempered glass facing the inside of the model box.

[0009] Optionally, the supporting steel cylinder, the model segment, the multi-layer prefabricated layer and the stainless steel sheet are sequentially sleeved from the inside to the outside to obtain an assembly, including:

[0010] Insert the supporting steel cylinder into the model segment; assemble the prefabricated layers to form a cylindrical structure, and the diameters of the multiple prefabricated layers just fit each other; apply polytetrafluoroethylene film and spray lubricating oil on the inner and outer surfaces of each prefabricated layer; insert the model segment into the innermost prefabricated layer, and then sleeve the prefabricated layers from the inside to the outside; assemble stainless steel sheets to form a cylindrical structure, apply polytetrafluoroethylene film and spray lubricating oil on the inner surface of the stainless steel sheets; sleeve the stainless steel sheet onto the outer surface of the outermost prefabricated layer to obtain an assembly.

[0011] Optionally, a model soil sample is filled in the model box, and the assembly and the micro soil pressure box are installed; a displacement meter is installed on the upper surface of the model soil sample; and a camera is installed outside the model soil sample, including:

[0012] The model box is filled with model soil samples in layers to the lowest height of the first circular hole by using the sand rain method, and each layer of the model soil sample is compacted by a tamping tool and has the same thickness; the assembly is placed horizontally inside the model box, with both ends passing through the first circular hole and the second circular hole respectively; a plurality of miniature soil pressure boxes are buried in the model soil sample; the model box is continuously filled with model soil samples in layers to a preset height by using the sand rain method; a displacement meter is installed on the top of the model soil sample; the model is left to stand until the indications of the displacement meter and the miniature soil pressure box no longer change; a camera is set up behind the model box, facing the rear tempered glass, so that the boundary of the model soil sample captured by the camera is clear, and continuous photography is performed at equal time intervals.

[0013] Optionally, the model segment is inserted into the innermost prefabricated layer, and then the prefabricated layers are installed in order from the inside to the outside, including:

[0014] There are two ways of arranging the multi-layer prefabricated layers. One is that the center line of one arcuate prefabricated sheet in the width direction is aligned with the vault ridge line of the model segment, and the other is that the joint formed by two adjacent arcuate prefabricated sheets is aligned with the vault ridge line of the model segment. The prefabricated layers using these two arrangements are staggered.

[0015] Optionally, extracting the arc-shaped prefabricated sheet in a preset order includes:

[0016] For prefabricated layers of different layers, pull them out layer by layer in the order from outside to inside; for prefabricated layers of the same layer, pull out the arc-shaped prefabricated pieces in the order from high to low and alternating left and right; pull out the arc-shaped prefabricated pieces of the prefabricated layers of the same layer continuously, and after completion, let them stand until the indications of the micro-earth pressure box and the displacement meter no longer change, and then pull out the next prefabricated layer.

[0017] Optionally, the diameter of the first circular hole is greater than the diameter of the assembly, and the diameter of the second circular hole is equal to the inner diameter of the model segment.

[0018] Optionally, a plurality of the micro earth pressure boxes are arranged circumferentially along the outer wall of the stainless steel sheet and arranged in layers along the height of the model box.

[0019] Optionally, the displacement meter includes a horizontal fixing rod and a plurality of sensors arranged at equal intervals, wherein the heads of all the displacement meters are in contact with the top of the model soil sample and the tails are fixedly connected to the fixing rod, and both ends of the fixing rod are fixedly connected to the model box by bolts.

[0020] The present application also provides a device for implementing a shield tunnel excavation simulation test method based on a plane strain mode, comprising:

[0021] A model box, wherein a model sample is arranged in the model box;

[0022] A front tempered glass, wherein the front tempered glass is arranged on a side wall of the model box.

[0023] A rear tempered glass, the rear tempered glass is arranged on the other side wall of the model box, and the front tempered glass and the rear tempered glass are arranged correspondingly;

[0024] An assembly, two ends of which are respectively arranged on the front tempered glass and the rear tempered glass;

[0025] A micro soil pressure box, wherein the micro soil pressure box is arranged in the model box;

[0026] A displacement meter is arranged on the top of the model box.

[0027] The beneficial effects of the present invention are:

[0028] The present invention adopts steel blocks to build the main structure of the model box, and installs tempered glass on the front and rear side walls to increase the overall rigidity of the model box and reduce the influence of the box deformation on the change of the stratum around the tunnel; by adopting tempered glass to replace part of the rear side wall area, a visualized study of the displacement field of the surrounding stratum under the plane strain mode in the transverse direction of the tunnel is realized; by pulling out the arc-shaped prefabricated pieces, artificial control of the quantitative deformation of the stratum is achieved, and then the excavation process of the shield tunnel in the stratum is simulated by combining the model pipe segment and the model box.

[0029] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or be understood by implementing the embodiments of the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description, claims, and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0031] Figure 1 It is a front side view schematic diagram of a model box of a shield tunnel excavation simulation test method based on a plane strain mode described in an embodiment of the present invention;

[0032] Figure 2 It is a schematic diagram of a rear side view of a model box of a shield tunnel excavation simulation test method based on a plane strain mode described in an embodiment of the present invention;

[0033] Figure 3 It is a schematic diagram of a method for fixing tempered glass in a shield tunnel excavation simulation test method based on a plane strain mode described in an embodiment of the present invention;

[0034] Figure 4 It is a schematic diagram of the assembly structure of the shield tunnel excavation simulation test method based on the plane strain mode described in an embodiment of the present invention;

[0035] Figure 5 It is a schematic diagram of the unfolding structure of the arc-shaped prefabricated piece of the shield tunnel excavation simulation test method based on the plane strain mode described in an embodiment of the present invention;

[0036] Figure 6 It is a schematic diagram of the structure of a micro earth pressure box of a shield tunnel excavation simulation test method based on a plane strain mode described in an embodiment of the present invention;

[0037] Figure 7 It is a schematic diagram of the structure of a displacement meter of the shield tunnel excavation simulation test method based on the plane strain mode described in an embodiment of the present invention.

[0038] Markings in the figure: 1. Model segment; 2. Support steel cylinder; 3. Prefabricated layer; 4. Model box; 5. Stainless steel sheet; 6. Curved prefabricated sheet; 7. Front tempered glass; 8. Rear tempered glass; 9. First circular hole; 10. Second circular hole; 11. Miniature earth pressure box; 12. Displacement meter; 13. Camera; 14. Sensor; 15. Fixing rod; 16. Channel steel; 17. Rubber strip. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. The components of the embodiments of the present invention generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0040] It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings. At the same time, in the description of the present invention, the terms "first", "second", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0041] Example:

[0042] like Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 and Figure 7 As shown, this embodiment provides a shield tunnel excavation simulation test method based on a plane strain mode, including:

[0043] According to the preset design scheme, the model box 4 is built, and the supporting steel cylinder 2, the model segment 1, the multi-layer prefabricated layer 3 and the stainless steel sheet 5 are sequentially sleeved from the inside to the outside to obtain an assembly, wherein each prefabricated layer 3 is composed of an even number of arc-shaped prefabricated sheets 6 of the same shape and size;

[0044] Fill the model box 4 with a model soil sample, install an assembly and a micro soil pressure box 11 in the model box 4, install a displacement meter 12 on the upper surface of the model soil sample, and install a camera 13 outside the model soil sample;

[0045] The model soil sample is left to stand until it is fully consolidated, the supporting steel cylinder 2 of the assembly is taken out, and after the indications of the micro soil pressure box 11 and the displacement meter 12 no longer change, the arc prefabricated sheet 6 is pulled out in a preset sequence, and the changes of the model soil sample during the pulling process are recorded by the micro soil pressure box 11, the displacement meter 12 and the camera 13.

[0046] It can be understood that the present invention uses steel blocks to build the main structure of the model box, and installs tempered glass on the front and rear side walls to increase the overall stiffness of the model box and reduce the impact of the box deformation on the changes in the strata around the tunnel; by using tempered glass to replace part of the rear side wall area, a visualization study of the displacement field of the surrounding strata under the plane strain mode in the cross-sectional direction of the tunnel is achieved; by pulling out the arc-shaped prefabricated pieces, artificial control of quantitative strata deformation is achieved, and then the model pipe segment and the model box are combined to simulate the excavation process of the shield tunnel in the stratum.

[0047] It is understandable that if Figure 3 Each prefabricated layer 3 in the present invention is a cylindrical structure surrounded by an even number of arc-shaped prefabricated sheets 6 of the same shape and size; the diameters of the multiple prefabricated layers 3 fit each other exactly, and the lengths of the multiple prefabricated layers 3 gradually decrease from the inner layer to the outer layer. In addition, the prefabricated layer 3 is made of flexible PVC material.

[0048] It can be understood that in the present invention, the number of arc-shaped prefabricated sheets 6 of each prefabricated layer 3 is six, the thickness is one millimeter, and the unfolded diagram thereof is as follows: Figure 4 The excavation process of the shield tunnel in the stratum is simulated by pulling out the arc-shaped prefabricated piece 6.

[0049] Among them, the model box 4 is built according to the preset design scheme, including:

[0050] The main body of the model box 4 is constructed using rigid materials;

[0051] A front tempered glass 7 and a rear tempered glass 8 are respectively installed on the front and rear sides of the main body of the model box 4, and the front tempered glass 7 and the rear tempered glass 8 are respectively provided with a first circular hole 9 and a second circular hole 10 at the same horizontal position;

[0052] A polytetrafluoroethylene film is applied to the inner wall of the model box 4 and the surfaces of the front tempered glass 7 and the rear tempered glass 8 facing the inside of the model box 4 .

[0053] It can be understood that in this step, the inner wall of the model box 4, the inner wall surfaces of the front tempered glass 7 and the rear tempered glass 8 are all coated with a polytetrafluoroethylene film with a thickness of 0.05 mm, which not only reduces the frictional resistance between the model soil sample and the model box 4, but also does not affect the transparency of the front tempered glass 7 and the rear tempered glass 8.

[0054] The supporting steel cylinder 2, the model segment 1, the multi-layer prefabricated layer 3 and the stainless steel sheet 5 are sequentially sleeved from the inside to the outside to obtain an assembly, including:

[0055] Insert the supporting steel cylinder 2 into the model segment 1;

[0056] Assemble the prefabricated layers 3 to form a cylindrical structure, and the diameters of the prefabricated layers 3 fit each other exactly;

[0057] Apply polytetrafluoroethylene film and spray lubricating oil on the inner and outer surfaces of each prefabricated layer 3;

[0058] Insert the model segment 1 into the innermost prefabricated layer 3, and then install each prefabricated layer 3 in order from the inside to the outside;

[0059] Assemble the stainless steel sheets 5 to form a cylindrical structure, apply a polytetrafluoroethylene film and spray lubricating oil on the inner surface of the stainless steel sheets 5;

[0060] The stainless steel sheet 5 is sleeved onto the outer surface of the outermost prefabricated layer 3 to obtain an assembly.

[0061] It is understandable that Figure 4 As shown, the outer wall of the outermost prefabricated layer 3 is wrapped with four stainless steel sheets 5, and the stainless steel sheets 5 are slidably connected to the outer wall of the outermost prefabricated layer 3; the four stainless steel sheets 5 are arc-shaped with the same shape and size, and their width is greater than the circumference of the outer wall of the outermost prefabricated layer 3. During the extraction process of the arc-shaped prefabricated sheet 6, the stainless steel sheets 5 remain stationary to avoid disturbance of the model soil sample by the extraction of the arc-shaped prefabricated sheet 6, and play the role of isolating the arc-shaped prefabricated sheet 6 from the prefabricated layer 3.

[0062] The support steel cylinder 2 is sleeved inside the model segment 1, and the outer wall of the support steel cylinder 2 is slidably connected to the inner wall of the model segment 1. The support steel cylinder 2 is made of high-strength steel and is not easily deformed. The support steel cylinder 2 is a temporary deformation constraint of the model segment 1, which is used to prevent the model segment 1 from deforming when the model box 4 is filled with the model soil sample.

[0063] The model box 4 is filled with a model soil sample, and an assembly and a micro soil pressure box 11 are installed; a displacement meter 12 is installed on the upper surface of the model soil sample; and a camera 13 is installed outside the model soil sample, including:

[0064] The model box 4 is filled with model soil samples in layers to the lowest height of the first circular hole 9 by using the sand rain method, and each layer of the model soil sample is compacted by a tamping machine and each layer of the model soil sample has the same thickness;

[0065] The assembly is placed horizontally inside the model box 4, with both ends passing through the first circular hole 9 and the second circular hole 10 respectively;

[0066] A plurality of micro soil pressure cells 11 are buried in the model soil sample;

[0067] Continue to fill the model box 4 with model soil samples in layers to a preset height by using the sand-rain method;

[0068] Install a displacement meter 12 on the top of the model soil sample;

[0069] Allow to stand until the displacement meter 12 and the micro earth pressure cell 11 readings no longer change;

[0070] The camera 13 is set up behind the model box 4, facing the rear tempered glass 8, so that the boundary of the model soil sample photographed by the camera 13 is clear, and the continuous photographing is performed in equal time intervals.

[0071] It is understandable that this step also includes setting up measuring equipment, including a micro soil pressure box 11 for monitoring soil pressure at different positions of the model soil, a displacement meter 12 for monitoring the settlement of the upper surface of the model soil, and a digital camera 13 for monitoring the deformation in the ground. The micro soil pressure box 11 is arranged inside the model box 4; the displacement meter 12 is installed on the top of the model soil sample; the support frame of the digital camera 13 is set at a distance behind the model box 4, and its lens is facing the rear tempered glass 8.

[0072] The model segment 1 is inserted into the innermost prefabricated layer 3, and then the prefabricated layers 3 are installed in order from the inside to the outside, including:

[0073] There are two arrangements of the multi-layer prefabricated layers 3. One is that the width direction center line of one of the arc-shaped prefabricated sheets 6 is aligned with the arch ridge line of the model segment 1. The other is that the joint formed by two adjacent arc-shaped prefabricated sheets 6 is aligned with the arch ridge line of the model segment 1.

[0074] The prefabricated layers 3 using these two arrangement modes are arranged in an interlaced manner.

[0075] It can be understood that the present invention arranges a prefabricated layer outside the model segment. There are two ways to arrange the prefabricated layers. The first is that the center line of one arc-shaped prefabricated piece in the width direction is directly opposite to the arch ridge line of the model segment. The second is that the joint formed by two adjacent arc-shaped prefabricated pieces of the same prefabricated layer is directly opposite to the arch ridge line of the model segment. The prefabricated layers using the first arrangement method and the prefabricated layers using the second arrangement method are staggered. After each prefabricated layer is sheathed, lubricating oil is sprayed on the surface. In this step, the formula for determining the number of prefabricated layers and the thickness of a single prefabricated layer is as follows:

[0076] ;

[0077] ;

[0078] in, represents the thickness of the precast layer, represents the outer diameter of the tunnel model, represents the designed total formation loss rate in the test, It represents the formation loss rate of a single precast layer extraction, Indicates the number of prefabricated layers.

[0079] The process of extracting the arc-shaped prefabricated sheet 6 in a preset order includes:

[0080] For different layers of prefabricated layers 3, pull them out layer by layer in the order from outside to inside;

[0081] For the prefabricated layer 3 of the same layer, the arc-shaped prefabricated sheets 6 are pulled out in the order from high to low and left to right alternately;

[0082] The arc-shaped prefabricated sheets 6 of the same prefabricated layer 3 are continuously pulled out, and after completion, they are left to stand until the readings of the micro-earth pressure box 11 and the displacement meter 12 no longer change, and then the next prefabricated layer 3 is pulled out.

[0083] It can be understood that the present invention extracts the prefabricated layer 3 layer by layer from the outer layer to the inner layer. The extraction order of the arc prefabricated sheet 6 of the same prefabricated layer 3 is from high to low, first the left side and then the right side or first the right side and then the left side. The arc prefabricated sheet 6 of the same prefabricated layer 3 is continuously extracted within a preset time period; after the extraction of the previous prefabricated layer 3 is completed, wait for a period of time before extracting the next layer. In this embodiment, the arc prefabricated sheet 6 of the same prefabricated layer 3 is continuously extracted within a preset time period; after the extraction of the previous prefabricated layer 3 is completed, wait for the readings of the micro-earth pressure box 11 and the displacement meter 12 to stabilize and no longer change before extracting the next layer.

[0084] The diameter of the first circular hole 9 is larger than the diameter of the assembly, and the diameter of the second circular hole 10 is equal to the inner diameter of the model segment 1 .

[0085] The plurality of micro earth pressure cells 11 are arranged circumferentially along the outer wall of the stainless steel sheet 5 , and are arranged in layers along the height of the model box 4 .

[0086] Furthermore, the displacement meter 12 includes a horizontal fixing rod 15 and a plurality of sensors 14 arranged at equal intervals, wherein the heads of all the displacement meters 12 are in contact with the top of the model soil sample and the tails are fixedly connected to the fixing rod 15, and both ends of the fixing rod 15 are fixedly connected to the model box 4 by bolts.

[0087] It can be understood that the displacement meter 12 in the present invention includes a sensor 14 and a fixing rod 15, the head of the sensor 14 contacts the top of the model soil sample, the tail of the sensor 14 is fixedly connected to the fixing rod 15, and both ends of the fixing rod 15 are fixedly connected to the model box 4 by bolts. The displacement meter 12 is used to monitor the change of the surface displacement value in real time, provide verification data for the measurement method of using a digital camera 13 to take images and PIV technology to process images, and verify the effect of the polytetrafluoroethylene film on the friction reduction of the inner wall of the model box 4.

[0088] Among them, this embodiment also provides a device for implementing a shield tunnel excavation simulation test method based on a plane strain mode, comprising:

[0089] A model box 4, wherein a model sample is arranged in the model box 4;

[0090] A front tempered glass 7, wherein the front tempered glass 7 is arranged on a side wall of the mold box 4,

[0091] A rear tempered glass 8, wherein the rear tempered glass 8 is arranged on the other side wall of the mold box 4, and the front tempered glass 7 and the rear tempered glass 8 are arranged correspondingly;

[0092] An assembly, the two ends of which are respectively arranged on the front tempered glass 7 and the rear tempered glass 8;

[0093] A micro earth pressure box 11, wherein the micro earth pressure box 11 is arranged in the model box 4;

[0094] The displacement meter 12 is arranged on the top of the model box 4 .

[0095] The present invention uses steel blocks to build the main structure of the model box 4, and installs tempered glass on the front and rear side walls to increase the overall rigidity of the model box 4 and reduce the influence of the box deformation on the change of the stratum around the tunnel; by using tempered glass to replace part of the rear side wall area, the visualization study of the displacement field of the surrounding stratum under the plane strain mode in the transverse direction of the tunnel is realized; by pulling out the arc-shaped prefabricated sheet, the quantitative deformation of the stratum is artificially controlled, and then the excavation process of the shield tunnel in the stratum is simulated by combining the model pipe segment and the model box 4. Among them, the assembly includes a supporting steel cylinder 2, a model pipe segment 1, a multi-layer prefabricated layer 3 and a stainless steel sheet 5, and the supporting steel cylinder 2, the model pipe segment 1, the multi-layer prefabricated layer 3 and the stainless steel sheet 5 are sequentially sleeved in order from the inside to the outside, wherein the supporting steel cylinder 2 is arranged inside the model pipe segment 1, the model pipe segment is arranged in the innermost prefabricated layer, and each layer of the prefabricated layer is assembled into a cylindrical structure, and the diameters of the multi-layer prefabricated layers just fit each other; the stainless steel sheet is sleeved on the outer surface of the outermost prefabricated layer.

[0096] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

[0097] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A shield tunnel excavation simulation test method based on plane strain mode, characterized in that: include: A model box (4) is constructed according to a preset design scheme, and a supporting steel cylinder (2), a model pipe segment (1), a multi-layer prefabricated layer (3) and a stainless steel sheet (5) are sequentially sleeved from the inside to the outside to obtain an assembly, wherein each prefabricated layer (3) is composed of an even number of arc-shaped prefabricated sheets (6) of the same shape and size; Filling the model box (4) with a model soil sample, installing an assembly and a micro soil pressure box (11) in the model box (4), installing a displacement meter (12) on the upper surface of the model soil sample, and installing a camera (13) outside the model soil sample; The model soil sample is left to stand until the model soil sample is fully consolidated, the supporting steel cylinder (2) of the assembly is taken out, and after the indications of the micro-soil pressure box (11) and the displacement meter (12) no longer change, the arc-shaped prefabricated piece (6) is pulled out in a preset sequence, and the changes of the model soil sample during the pulling process are recorded by the micro-soil pressure box (11), the displacement meter (12) and the camera (13); The model box (4) is constructed according to a preset design scheme, including: The main body of the model box (4) is constructed using rigid materials; A front tempered glass (7) and a rear tempered glass (8) are respectively installed on the front and rear sides of the main body of the model box (4), and the front tempered glass (7) and the rear tempered glass (8) are respectively provided with a first circular hole (9) and a second circular hole (10) at the same horizontal position; A polytetrafluoroethylene film is applied to the inner wall of the model box (4) and the surfaces of the front tempered glass (7) and the rear tempered glass (8) facing the inside of the model box (4); The supporting steel cylinder (2), the model pipe segment (1), the multi-layer prefabricated layer (3) and the stainless steel sheet (5) are sequentially sleeved from the inside to the outside to obtain an assembly, comprising: Inserting the supporting steel cylinder (2) into the model segment (1); Assembling the prefabricated layers (3) to form a cylindrical structure, wherein the diameters of the prefabricated layers (3) fit each other exactly; Applying polytetrafluoroethylene film and spraying lubricating oil on the inner and outer surfaces of each prefabricated layer (3); Inserting the model pipe segment (1) into the innermost prefabricated layer (3), and then sleeve each prefabricated layer (3) in order from the inside to the outside; Assembling stainless steel sheets (5) to form a cylindrical structure, applying a polytetrafluoroethylene film and spraying lubricating oil on the inner surface of the stainless steel sheets (5); The stainless steel sheet (5) is sleeved onto the outer surface of the outermost prefabricated layer (3) to obtain an assembly.

2. The shield tunnel excavation simulation test method based on plane strain mode according to claim 1 is characterized in that: A model soil sample is filled in a model box (4), and an assembly and a micro soil pressure box (11) are installed; a displacement meter (12) is installed on the upper surface of the model soil sample; and a camera (13) is installed outside the model soil sample, including: Using the sand-rain method, the model box (4) is filled with model soil samples in layers to the lowest height of the first circular hole (9), and each layer of the model soil sample is compacted by a tamping machine and each layer of the model soil sample has the same thickness; The assembly is placed horizontally inside the model box (4), with both ends passing through the first circular hole (9) and the second circular hole (10) respectively; A plurality of micro soil pressure boxes (11) are buried in the model soil sample; Continue to fill the model box (4) with model soil samples in layers to a preset height by using the sand-rain method; Installing a displacement meter (12) on the top of the model soil sample; Allow to stand until the readings of the displacement meter (12) and the micro earth pressure cell (11) no longer change; The camera (13) is set up behind the model box (4) and directly facing the rear tempered glass (8), so that the boundary of the model soil sample photographed by the camera (13) is clear, and continuous photographing is performed at equal time intervals.

3. The shield tunnel excavation simulation test method based on plane strain mode according to claim 1 is characterized in that: Inserting the model segment (1) into the innermost prefabricated layer (3), and then sleeve each prefabricated layer (3) in order from the inside to the outside, including: There are two arrangements of the multi-layer prefabricated layers (3), one of which is that the width direction center line of one of the arc-shaped prefabricated sheets (6) is aligned with the arch ridge line of the model pipe segment (1), and the other is that the joint formed by two adjacent arc-shaped prefabricated sheets (6) is aligned with the arch ridge line of the model pipe segment (1); The prefabricated layers (3) using these two arrangement modes are arranged in an interlaced manner.

4. The shield tunnel excavation simulation test method based on plane strain mode according to claim 1 is characterized in that: The arc-shaped prefabricated sheet (6) is extracted according to a preset sequence, comprising: For different layers of prefabricated layers (3), extract them layer by layer in the order from outside to inside; For the prefabricated layers (3) on the same layer, the arc-shaped prefabricated sheets (6) are pulled out in a sequence from high to low and alternately from left to right; The arc-shaped prefabricated sheets (6) of the same prefabricated layer (3) are continuously pulled out, and after completion, they are left to stand until the readings of the micro-earth pressure box (11) and the displacement meter (12) no longer change, and then the next prefabricated layer (3) is pulled out.

5. The shield tunnel excavation simulation test method based on plane strain mode according to claim 1 is characterized in that: The diameter of the first circular hole (9) is greater than the diameter of the assembly, and the diameter of the second circular hole (10) is equal to the inner diameter of the model segment (1).

6. The shield tunnel excavation simulation test method based on plane strain mode according to claim 1 is characterized in that: The plurality of micro earth pressure boxes (11) are arranged in a circumferential direction along the outer wall of the stainless steel sheet (5) and are arranged in layers along the height of the model box (4).

7. The shield tunnel excavation simulation test method based on plane strain mode according to claim 1 is characterized in that: The displacement meter (12) comprises a horizontal fixing rod (15) and a plurality of sensors (14) arranged at equal intervals, wherein the heads of all the displacement meters (12) are in contact with the top of the model soil sample and the tails are fixedly connected to the fixing rod (15), and the two ends of the fixing rod (15) are fixedly connected to the model box (4) by bolts.

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