Tunnel excavation support model test device and test method

Abstract

The present invention belongs to the field of indoor testing in geotechnical engineering and relates to a tunnel excavation support model test device and test method. The device includes a model stand, a horizontal loading device, a vertical loading device, a tunnel model fixture, and a data acquisition system. The tunnel model fixture is disposed on the model stand; a model to be tested is disposed in the tunnel model fixture; a horizontal loading device and a vertical loading device are respectively disposed on the model stand; the horizontal loading device passes through the tunnel model fixture and acts on the model to be tested, applying a horizontal load to the model to be tested; the vertical loading device passes through the tunnel model fixture and acts on the model to be tested, applying a vertical load to the model to be tested; the data acquisition system is used to measure the displacement and load of the loading system and to monitor and collect strain data of the model to be tested. The present invention can verify the theoretical calculation method of the safety factor of different support structures in the total safety factor method.

Description

Technical Field

[0001] The present invention belongs to the field of geotechnical engineering indoor testing, and relates to a tunnel excavation support model testing device and a testing method, and in particular to a tunnel excavation support model testing device and a testing method based on the design theory of the total safety factor method. Background Art

[0002] Tunnel engineering has seen significant innovations in surrounding rock properties, surrounding rock pressure, support materials, support mechanisms, support-rock interaction, support structure calculation methods, and the management of special surrounding rock and unfavorable geological conditions, resulting in a wealth of engineering experience and design and construction theories. Commonly used support structure design methods include engineering analogy, load-structure method, stratum structure method, and characteristic curve method. For various reasons, this approach remains primarily empirical, supplemented by calculations. Quantitative design of support parameters is impossible, making it impossible to analyze and evaluate the safety and economic efficiency of tunnel support structures.

[0003] The total safety factor method for tunnel support structure design has preliminarily established a quantitative design system for tunnel support structures, which can realize the transformation of tunnel support structures from "analogous design" to "quantitative design" and has a positive effect on promoting the development of tunnel engineering design technology.

[0004] The total safety factor method treats the composite lining structure as a multi-layered structure. The safety of each layer is calculated using the load-structure method, and then the total safety factor of the overall structure is calculated. The structural design and solution process of the total safety factor method is as follows: First, the design value of the surrounding rock pressure is calculated to determine the total safety factor of the composite lining. The calculation model of the shotcrete layer, the anchor rock bearing arch calculation model, and the secondary lining calculation model are allocated and combined, and the corresponding parameters are formulated. After checking the safety factor, an overall solution is obtained. Combined with the load proportionality coefficient of the overall failure stage of the composite structure, the feasibility and economic efficiency of the solution are considered, and a relatively ideal result is finally achieved.

[0005] At present, the total safety factor method is limited to the above theoretical calculations. Experimental research is needed to revise and improve the design method, for example:

[0006] 1) The total safety factor method proposes calculation methods for the bearing capacity of the anchor rock bearing arch, shotcrete layer, and secondary lining, which urgently need to be verified by model tests;

[0007] 2) Since the safety factors of the anchor rock bearing arch, shotcrete layer, and secondary lining are calculated relatively independently in the total safety factor method, the total safety factor of the composite support is obtained by superimposing these safety factors and needs to be revised and improved through model testing.

[0008] 3) Because the three-layer structure of anchor rock bearing arch, shotcrete layer, and secondary lining bears both shared and distinct loads, the overall structural design is a complex issue. Model testing is required to further explore the bearing mechanism of the composite support structure.

[0009] Based on the above problems, it is particularly important to study the support effect and bearing capacity of anchor rock bearing arch, shotcrete, secondary lining and composite support, as well as to verify and correct the safety factor methods of various calculation models in order to improve the total safety factor design system. Summary of the Invention

[0010] In order to solve the above technical problems existing in the background technology, the present invention provides a tunnel excavation support model test device for analyzing the stress characteristics of the support structure of a large-scale tunnel and verifying the theoretical calculation method of the safety factor of different support structures in the total safety factor method.

[0011] In order to achieve the above object, the present invention adopts the following technical solutions:

[0012] A tunnel excavation support model test device, characterized in that: the tunnel excavation support model test device includes a model stand, a loading system, a tunnel model fixing device and a data acquisition system; the tunnel model fixing device is arranged on the model stand; the model to be tested is arranged in the tunnel model fixing device; the loading system includes a horizontal loading device and a vertical loading device; the horizontal loading device and the vertical loading device are respectively arranged on the model stand; the horizontal loading device passes through the tunnel model fixing device and acts on the model to be tested and applies a horizontal load to the model to be tested; the vertical loading device passes through the tunnel model fixing device and acts on the model to be tested and applies a vertical load to the model to be tested; the data acquisition system is used to measure the displacement and load of the loading system and to monitor and collect strain data of the model to be tested.

[0013] Preferably, the horizontal loading device adopted in the present invention includes a left-side loading device and a right-side loading device which is symmetrically arranged with the left-side loading device and has the same structure as the horizontal loading device; the left-side loading device includes a side loading cylinder, a first loading body, and a loading plate; the side loading cylinder is connected to the loading plate through the first loading body; the side loading cylinder is arranged on the model stand; the first loading body passes through the tunnel model fixing device; the loading plate acts on the model to be tested; the first loading body is one or more, and when the first loading body is multiple, the number of the loading plates is the same as the number of the first loading bodies; the side loading cylinder is connected to the loading plate through multiple first loading bodies, and the multiple first loading bodies are arranged in sequence from top to bottom along the vertical direction; the loading plate is a regular tetrahedron.

[0014] Preferably, the first loading body adopted in the present invention includes a displacement sensor, a horizontal jack and a force sensor; the side loading cylinder is connected to the loading plate through the horizontal jack; the displacement sensor is placed on the loading plate; the force sensor is placed between the side loading cylinder and the horizontal jack; the force sensor and the displacement sensor are respectively connected to the data acquisition system.

[0015] Preferably, the vertical loading device adopted in the present invention includes an upper loading cylinder, a second loading body and a loading plate; the upper loading cylinder is connected to the loading plate through the second loading body; the upper loading cylinder is arranged on the model stand; the second loading body passes through the tunnel model fixing device; the loading plate acts on the model to be tested; the second loading body is one or more, and when the second loading body is multiple, the number of the loading plates is the same as the number of the second loading bodies; the upper loading cylinder is connected to the loading plate through multiple second loading bodies, and the multiple second loading bodies are arranged in sequence from left to right along the horizontal direction; the loading plate is a regular tetrahedron.

[0016] Preferably, the second loading body adopted in the present invention includes a displacement sensor, a force sensor, a heavy-load ball head and an upper row of jacks; the upper loading cylinder is connected to the loading plate through the heavy-load ball head and the upper row of jacks; the displacement sensor is arranged on the loading plate; the force sensor is arranged between the heavy-load ball head and the upper row of jacks; the force sensor and the displacement sensor are respectively connected to the data acquisition system.

[0017] Preferably, the loading system adopted in the present invention also includes an anti-interference guide loading mechanism; the anti-interference guide loading mechanism is a rectangular steel plate; the anti-interference guide loading mechanism is arranged on both sides of the top of the model to be tested; the stroke terminal of the horizontal loading device and / or the stroke terminal of the vertical loading device rests on the anti-interference guide loading mechanism.

[0018] Preferably, the tunnel model fixing device adopted in the present invention includes a front fixed steel plate, a removable steel plate, a removable baffle and an organic glass window; the front fixed steel plates are multiple, and the multiple front fixed steel plates form a columnar structure containing a hollow cavity; the model to be tested is arranged in the hollow cavity surrounded by the front fixed steel plates along the axial direction of the columnar structure; the removable steel plate and the removable baffle are respectively arranged at the front end and the rear end of the hollow cavity; a groove is provided in the front fixed steel plate; the data acquisition system is placed in the groove; the organic glass window is embedded in the front fixed steel plate and arranged around the removable steel plate; the horizontal loading device acts on the model to be tested after passing through the columnar structure and applies a horizontal load to the model to be tested; the vertical loading device acts on the model to be tested after passing through the columnar structure and applies a vertical load to the model to be tested.

[0019] Preferably, the data acquisition system used in the present invention includes a monitoring device and a data analysis system connected to the monitoring device, wherein the monitoring device is placed in the groove of the front fixed steel plate, and the data analysis system is used to measure the displacement and load of the loading system and to monitor and collect strain data of the model to be tested through the monitoring device; the monitoring device is an XTDIC system; and the data analysis system is an industrial control computer.

[0020] Preferably, the model stand adopted in the present invention includes a top crossbeam, side reaction columns and a base; the side reaction columns are two groups; the two groups of side reaction columns are symmetrical and fixed on the base; the top crossbeam is parallel to the base; the top crossbeam is connected to the two groups of side reaction columns respectively through a fixed steel frame; the fixed steel frame is a connecting member with an overall triangular structure; the top crossbeam, side reaction columns and base constitute a gantry structure as a whole; the tunnel model fixing device is placed on the base; the horizontal loading device is arranged on the side reaction columns; the vertical loading device is arranged on the top crossbeam.

[0021] A test method based on the tunnel excavation support model test device as described above is characterized in that the test method comprises the following steps:

[0022] 1) Preparation: Prepare similar test materials, prepare tools for model preparation, filling, compaction, and various auxiliary materials such as sensor elements, and check whether all parts of the test instrument are normal;

[0023] 2) The tunnel model fixture is filled with similar test materials using the layered paving and compaction method to form a test model. Monitoring elements, including micro earth pressure cells, displacement gauges, and strain gauges, are then embedded at the designed elevation.

[0024] 3) Fixing the tunnel model fixture prepared in step 2) on the model stand; embedding the organic glass plate into the front fixing steel plate;

[0025] 4) Apply load to the test model through the loading system according to the test requirements;

[0026] 5) Through the data acquisition system, the displacement, applied load and stress data of similar materials and support structures in the test model are monitored and collected in real time, and the test results are analyzed. After obtaining the test results, the test is completed.

[0027] Compared with the prior art, the present invention has the following advantages:

[0028] (1) Most existing tunnel model tests are small-scale tests, and the stress and failure forms of various support components such as lining and anchors are difficult to monitor. The purpose of this test is to analyze the stress characteristics of the tunnel support structure, which is more inclined to structural testing. Therefore, a large scale size is used to facilitate the monitoring of the support structure.

[0029] (2) In existing tunnel model tests, due to the large similarity ratio, the diameter, length, strength, and elastic modulus of the anchor material are generally very small. The adhesive is applied to the outside of the anchor material for pre-embedding, but the bonding effect is usually poor, making it difficult to show the effect of the anchor rock bearing arch. This test device intends to use larger anchor material, and after the model body is completed, drill holes to inject adhesive and apply anchor material to achieve the effect of the anchor.

[0030] (3) Many studies on tunnel structures simulate actual excavation conditions or actual stress states. According to the safety factor method, the safety factor corresponds to the limit state of the structure, and it is necessary to study the ultimate bearing capacity of the support structure.

[0031] (4) This test device uses four movable steel plates as detachable baffles, which facilitates the compaction of similar materials layer by layer by manual or rammer methods; organic glass windows are reserved around the tunnel model cavity and equipped with organic glass, which can be used to observe the deformation of the soil during the test.

[0032] The present invention discloses a tunnel excavation support model test device based on the design theory of the total safety factor method. The main components of the test device are composed of high-strength steel plates, and its structure includes a model stand, a loading system and a data acquisition system. Among them, the model stand is used to provide a space for holding the test model and provide a reaction force for the loading system; the loading system is used to simultaneously control different loading bodies to realize the loading test of the test model; the data acquisition system is used to detect the real-time displacement and real-time compressive stress of the test model during the loading test. The tunnel excavation support model test device based on the total safety factor method can realize the support structure design and optimize the support parameters; adopt a large scale size to analyze the stress characteristics of the tunnel support structure, and tend to structural testing; this device can use larger-sized anchor rod materials, and after the model body is completed, drill holes to inject adhesives and apply anchor rod materials to maximize the role of the anchor rods; through multiple detachable steel plates, the effect of spreading the compacted material layer by layer can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a front three-dimensional structural schematic diagram of the tunnel excavation support model test device provided by the present invention;

[0034] Figure 2 This is a schematic diagram of the back three-dimensional structure of the tunnel excavation support model test device provided by the present invention;

[0035] Figure 3 This is a rear view of the tunnel excavation support model test device provided by the present invention;

[0036] Figure 4 2 is a schematic structural diagram of the front baffle adopted in the present invention;

[0037] Figure 5 This is a schematic structural diagram of the detachable baffle used in the present invention;

[0038] Figure 6 This is a schematic diagram of the upper loading cylinder structure used in the present invention;

[0039] Figure 7 This is a schematic diagram of the side loading cylinder structure used in the present invention;

[0040] In the picture:

[0041] 1-upper loading cylinder; 2-top crossbeam; 3-fixed steel frame; 4-side reaction column; 5-side loading cylinder; 6-loading plate; 7-vertical rib fixing support; 8-front fixed steel plate; 9-removable steel plate; 10-base; 12-removable baffle; 13-plexiglass window; 14-bolt mouth; 15-adjustment plate; 16-displacement sensor; 17-force sensor; 18-heavy-load ball head; 19-upper row jack; 20-horizontal jack; 21-vertical rib. DETAILED DESCRIPTION

[0042] To demonstrate the feasibility of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings in the specification.

[0043] See also Figure 1 、 Figure 2 as well as Figure 3 The present invention provides a tunnel excavation support model test device, comprising a model stand, a loading system, a tunnel model fixture, and a data acquisition system; the tunnel model fixture is arranged on the model stand; the model to be tested is arranged in the tunnel model fixture; the loading system comprises a horizontal loading device and a vertical loading device; the horizontal loading device and the vertical loading device are respectively arranged on the model stand; the horizontal loading device passes through the tunnel model fixture and acts on the model to be tested and applies a horizontal load to the model to be tested; the vertical loading device passes through the tunnel model fixture and acts on the model to be tested and applies a vertical load to the model to be tested. The model stand is used to provide a space for holding the test model and to provide a reaction force for the loading system; the loading system comprises a plurality of loading bodies, which are used to simultaneously control different loading bodies to realize a loading test on the test model; the data acquisition system is used to measure the displacement and load of the loading system and to monitor and collect strain data of the model box to be tested.

[0044] Among them, the horizontal loading device includes a left-side loading device and a right-side loading device which is symmetrically arranged with the left-side loading device and has the same structure as the horizontal loading device; the left-side loading device includes a side loading cylinder 5, a first loading body, and a loading plate 6; the side loading cylinder 5 is connected to the loading plate 6 through the first loading body; the side loading cylinder 5 is arranged on the model stand; the first loading body passes through the tunnel model fixing device; the loading plate 6 acts on the model to be tested; the first loading body is one or more, and when there are multiple first loading bodies, the number of loading plates 6 is the same as the number of first loading bodies; the side loading cylinder 5 is connected to the loading plate 6 through multiple first loading bodies, and the multiple first loading bodies are arranged in sequence from top to bottom along the vertical direction.

[0045] Loading plate 6 is a regular rectangular pyramid constructed from high-strength steel. The upper loading plate is a hexahedron with isosceles trapezoidal sides of equal size. Its upper and lower surfaces are smooth, with the upper surface being a smaller square and the lower surface being a larger square. The upper surface is connected to the three-way loading mechanism, while the lower surface contacts similar materials. The two loading plates share the same specifications as the upper loading plate and function to evenly distribute the jack's load across the soil surface, achieving balanced load distribution.

[0046] See also Figure 7 The first loading body used in the present invention includes a displacement sensor 16, a horizontal jack 20 and a force sensor 17; the side loading cylinder 5 is connected to the loading plate 6 through the horizontal jack 20; the displacement sensor 16 is placed on the loading plate 6; the force sensor 17 is placed between the side loading cylinder 5 and the horizontal jack 20; the force sensor 17 and the displacement sensor 16 are respectively connected to the data acquisition system. The side loading cylinder 5 is the force application system in the loading system, and the load is applied to the loading plate 6 through a number of horizontal jacks 20. The hydraulic system is equipped with a proportional valve and an accumulator for pressurization control and pressure stabilization control, so that the loading process can be stress-controlled and can be loaded under different stress conditions. The horizontal jacks 20 are loaded simultaneously through servo to ensure that the compressive stress is large enough and that relative displacement does not occur in the same cross section.

[0047] The vertical loading device includes an upper loading cylinder 1, a second loading body and a loading plate 6; the upper loading cylinder 1 is connected to the loading plate 6 through the second loading body; the upper loading cylinder 1 is set on the model stand; the second loading body passes through the tunnel model fixing device; the loading plate 6 acts on the model to be tested; the second loading body is one or more, and when there are multiple second loading bodies, the number of loading plates 6 is the same as the number of second loading bodies; the upper loading cylinder 1 is connected to the loading plate 6 through multiple second loading bodies, and the multiple second loading bodies are arranged in sequence from left to right along the horizontal direction; the loading plate 6 is a regular tetrahedron.

[0048] See also Figure 6The second loading body used in the present invention includes a displacement sensor 16, a force sensor 17, a heavy-load ball head 18 and an upper row of jacks 19; the upper loading cylinder 1 is connected to the loading plate 6 through the heavy-load ball head 18 and the upper row of jacks 19; the displacement sensor 16 is arranged on the loading plate 6; the force sensor 17 is arranged between the heavy-load ball head 18 and the upper row of jacks 19; the force sensor 17 and the displacement sensor 16 are respectively connected to the data acquisition system. The displacement sensor is mainly used to check the loading displacement of the cylinder to ensure that the cylinder stroke displacement is safe and reliable. The force sensor is mainly used to dynamically monitor the real-time load, and can accurately detect the load applied to the specimen by the specimen jack, and accurately simulate the stress state of the loading. The load sensor equipped with the hydraulic system directly monitors the pressure and feeds back to the computer system.

[0049] See also Figure 6 as well as Figure 7 The upper loading cylinder 1 and the side loading cylinders 5 on either side transfer the load from the hydraulic system to the loading plate 6 connected to the soil. To accommodate vertical and horizontal loads, a row of jacks is installed on each of the top, left, and right sides of the model box. The upper row has four jacks, while the left and right rows each have four jacks. This provides both vertical and horizontal loads.

[0050] The loading system also includes an anti-interference guide loading mechanism; the anti-interference guide loading mechanism is a rectangular steel plate; the anti-interference guide loading mechanism is arranged on both sides of the top of the model to be tested; the travel terminal of the horizontal loading device and / or the travel terminal of the vertical loading device rest on the anti-interference guide loading mechanism. The anti-interference guide loading mechanism is a safety mechanism of the loading system. During the loading process, the loads acting in the vertical and horizontal directions are usually very large and in vertical directions. In order to avoid interference between the vertical and horizontal loading plates 6, the anti-interference guide loading mechanism can effectively control the stroke of the jack. By controlling the stroke of the jack, it can be pushed inward by 150 mm by the horizontal loading plate, and can be pushed inward by 250 mm by the vertical loading plate, ensuring the rational use of the test device and ensuring that the test is completed within a safe range.

[0051] The tunnel model fixing device includes a front fixed steel plate 8, a removable steel plate 9, a removable baffle 12 and an organic glass window 13; there are multiple front fixed steel plates 8, and the multiple front fixed steel plates 8 form a columnar structure containing a hollow cavity; the model to be tested is arranged in the hollow cavity surrounded by the front fixed steel plates 8 along the axial direction of the columnar structure; the removable steel plate 9 and the removable baffle 12 are respectively arranged at the front and rear ends of the hollow cavity; a groove is provided in the front fixed steel plate 8; the data acquisition system is placed in the groove; the organic glass window 13 is embedded in the front fixed steel plate 8 and is arranged around the removable steel plate 9; the horizontal loading device passes through the columnar structure and acts on the model to be tested and applies a horizontal load to the model to be tested; the vertical loading device passes through the columnar structure and acts on the model to be tested and applies a vertical load to the model to be tested. The removable baffle 9 is fixed to the middle part of the front fixed steel plate 8 by bolts, which is to facilitate the excavation of the tunnel mold. Figure 5 , multiple bolt holes 14 are provided at both ends of the removable baffle 12, which can be fixed to the rear support of the model test box by several bolts, and equipped with several adjustment plates 15 to facilitate the installation of the baffle. The front fixed steel plate 8 is sealed by a removable cover plate 9 near the tunnel model cavity. The soil, strain bricks, prefabricated sensors and tunnel model are filled into the model box and compacted according to the test requirements. Then the removable cover plate 9 is removed, the test model is extracted from the soil, and the sensors required for the test are arranged in the tunnel hole. Then, the hydraulic cylinder is used to load the model body on both sides, implementing the process of "excavation first and then loading". The deformation state of the soil during the loading process of the specimen can be observed through the tempered glass 13 above the tunnel model cavity. Figure 4 There is a groove on the inner side of the front fixed steel plate 8, the depth of which is just enough to embed the organic glass plate into the groove, so that the displacement of the specimen can be observed without affecting the test model. The removable baffle 12 is the compacting device of the model stand. Since the similarity ratio of the model box is 12.5 and it is a large-scale test, compaction is difficult. Therefore, the removable baffle is set as a movable steel plate, and the compacted material is spread layer by layer by manual or rammer methods. After the compaction is completed and the rear cover is fixed, the vertical rib 21 is fixed to the vertical rib fixing support 7 at the upper rear of the model box by bolts, fitting with the rear cover to limit the longitudinal displacement of the soil.

[0052] The data acquisition system includes a monitoring device and a data analysis system connected to the monitoring device. The monitoring device is placed in the groove of the front fixed steel plate 8. The data analysis system is used to measure the displacement and load of the loading system and to monitor and collect strain data of the test model through the monitoring device. The monitoring device is the XTDIC system; the data analysis system is an industrial control computer. Figure 4The model box has a pre-set plexiglass observation window. The XTDIC system, combining digital image correlation (DIC) and binocular stereo vision technology, tracks speckle patterns on the surface to measure the object's three-dimensional coordinates, displacement, and strain during deformation. The data analysis system comprises an industrial control computer, multiple slave computers, and various signal sensors, forming a closed-loop control system. The master control computer is installed in a dedicated console, while the slave control computers can be installed in off-site offices via network transmission, providing full monitoring and control of the test progress.

[0053] See also Figure 1 as well as Figure 2 The model test bench used in the present invention includes a top crossbeam 2, side reaction columns 4, and a base 10; there are two groups of side reaction columns 4; the two groups of side reaction columns 4 are symmetrical and fixed on the base 10; the top crossbeam 2 is parallel to the base 10; the top crossbeam 2 is connected to the two groups of side reaction columns 4 respectively through a fixed steel frame 3; the fixed steel frame 3 is a connecting member with an overall triangular structure; the top crossbeam 2, side reaction columns 4, and base 10 form a gantry structure as a whole; the tunnel model fixing device is placed on the base 10; the horizontal loading device is set on the side reaction columns 4; and the vertical loading device is set on the top crossbeam 2. The base 10 is connected to the side reaction columns 4 by high-strength bolts, and its function is to provide reaction force and stabilize the test bench.

[0054] A test method based on the tunnel excavation support model test device as described above, the test method comprising the following steps:

[0055] 1) Preparation: Prepare similar test materials, prepare tools for model preparation, filling, compaction, and various auxiliary materials such as sensor elements, and check whether all parts of the test instrument are normal;

[0056] 2) The tunnel model fixture is filled with similar test materials using the layered paving and compaction method to form a test model. Monitoring elements, including micro earth pressure cells, displacement gauges, and strain gauges, are then embedded at the designed elevation.

[0057] 3) Fixing the tunnel model fixture prepared in step 2) on the model stand; embedding the organic glass plate into the front fixing steel plate 8;

[0058] 4) Apply load to the test model through the loading system according to the test requirements;

[0059] 5) Through the data acquisition system, the displacement, applied load and stress data of similar materials and support structures in the test model are monitored and collected in real time, and the test results are analyzed. After obtaining the test results, the test is completed.

Claims

1. A tunnel excavation support model test device, characterized by: The tunnel excavation support model test device includes a model stand, a loading system, a tunnel model fixing device and a data acquisition system; the tunnel model fixing device is arranged on the model stand; The model to be tested is set in a tunnel model fixture; the loading system includes a horizontal loading device and a vertical loading device; the horizontal loading device and the vertical loading device are respectively set on the model stand; the horizontal loading device passes through the tunnel model fixture and acts on the model to be tested and applies a horizontal load to the model to be tested; the vertical loading device passes through the tunnel model fixture and acts on the model to be tested and applies a vertical load to the model to be tested; the data acquisition system is used to measure the displacement and load of the loading system and to monitor and collect strain data of the model to be tested; The horizontal loading device comprises a left loading device and a right loading device which is symmetrically arranged with the left loading device and has the same structure as the horizontal loading device; the left loading device comprises a side loading cylinder (5), a first loading body, and a loading plate (6); the side loading cylinder (5) is connected to the loading plate (6) through the first loading body; the side loading cylinder (5) is arranged on the model stand; the first loading body passes through the tunnel model fixing device; the loading plate (6) acts on the model to be tested; the first loading body is one or more, and when the first loading body is multiple, the number of the loading plates (6) is the same as the number of the first loading bodies; the side loading cylinder (5) is connected to the loading plate (6) through multiple first loading bodies, and the multiple first loading bodies are arranged in sequence from top to bottom in the vertical direction; the loading plate (6) is a regular tetrahedron; The vertical loading device comprises an upper loading cylinder (1), a second loading body and a loading plate (6); the upper loading cylinder (1) is connected to the loading plate (6) via the second loading body; the upper loading cylinder (1) is arranged on the model stand; the second loading body passes through the tunnel model fixing device; the loading plate (6) acts on the model to be tested; the second loading body is one or more, and when the second loading body is multiple, the number of the loading plates (6) is the same as the number of the second loading bodies; the upper loading cylinder (1) is connected to the loading plate (6) via multiple second loading bodies, and the multiple second loading bodies are arranged in sequence from left to right along the horizontal direction; the loading plate (6) is a regular tetrahedron; The loading system further includes an anti-interference guide loading mechanism; the anti-interference guide loading mechanism is a rectangular steel plate; the anti-interference guide loading mechanism is disposed on both sides of the top of the model to be tested; the travel ends of the horizontal loading device and / or the travel ends of the vertical loading device rest on the anti-interference guide loading mechanism; The tunnel model fixing device comprises a front fixing steel plate (8), a detachable steel plate (9), a detachable baffle (12) and an organic glass window (13); the front fixing steel plates (8) are multiple, and the multiple front fixing steel plates (8) form a columnar structure containing a hollow cavity; The model to be tested is arranged in a hollow cavity surrounded by a front fixed steel plate (8) along the axial direction of the columnar structure; the detachable steel plate (9) and the detachable baffle (12) are respectively arranged at the front end and the rear end of the hollow cavity; a groove is provided in the front fixed steel plate (8); the data acquisition system is placed in the groove; the organic glass window (13) is embedded in the front fixed steel plate (8) and arranged around the detachable steel plate (9); the horizontal loading device penetrates the columnar structure and acts on the model to be tested and applies a horizontal load to the model to be tested; the vertical loading device penetrates the columnar structure and acts on the model to be tested and applies a vertical load to the model to be tested.

2. The tunnel excavation support model test device according to claim 1, characterized in that: The first loading body comprises a displacement sensor (16), a horizontal jack (20) and a force sensor (17); the side loading cylinder (5) is connected to the loading plate (6) via the horizontal jack (20); the displacement sensor (16) is placed on the loading plate (6); the force sensor (17) is placed between the side loading cylinder (5) and the horizontal jack (20); and the force sensor (17) and the displacement sensor (16) are respectively connected to a data acquisition system.

3. The tunnel excavation support model test device according to claim 2, characterized in that: The second loading body comprises a displacement sensor (16), a force sensor (17), a heavy-load ball head (18) and an upper row of jacks (19); the upper loading cylinder (1) is connected to the loading plate (6) via the heavy-load ball head (18) and the upper row of jacks (19); the displacement sensor (16) is arranged on the loading plate (6); the force sensor (17) is arranged between the heavy-load ball head (18) and the upper row of jacks (19); the force sensor (17) and the displacement sensor (16) are respectively connected to a data acquisition system.

4. The tunnel excavation support model test device according to claim 3, characterized in that: The data acquisition system comprises a monitoring device and a data analysis system connected to the monitoring device, wherein the monitoring device is placed in a groove of the front fixed steel plate (8), and the data analysis system is used to measure the displacement and load of the loading system and to monitor and collect strain data of the model to be tested through the monitoring device; the monitoring device is an XTDIC system; and the data analysis system is an industrial control computer.

5. The tunnel excavation support model test device according to claim 4, characterized in that: The model stand comprises a top crossbeam (2), side reaction columns (4) and a base (10); the side reaction columns (4) are two groups; the two groups of side reaction columns (4) are symmetrical and fixedly arranged on the base (10); the top crossbeam (2) is parallel to the base (10); the top crossbeam (2) is respectively connected to the two groups of side reaction columns (4) through a fixed steel frame (3); the fixed steel frame (3) is a connecting member with an overall triangular structure; the top crossbeam (2), the side reaction columns (4) and the base (10) constitute a gantry structure as a whole; the tunnel model fixing device is placed on the base (10); the horizontal loading device is arranged on the side reaction columns (4); and the vertical loading device is arranged on the top crossbeam (2).

6. A test method based on the tunnel excavation support model test device according to claim 5, characterized in that: The test method comprises the following steps: 1) Preparation: Prepare similar test materials, prepare model preparation, filling, compaction tools and various sensor component auxiliary materials, and check whether all parts of the test instrument are normal; 2) The tunnel model fixture is filled with similar test materials using the layered paving and compaction method to form a test model. Monitoring elements, including micro earth pressure cells, displacement gauges, and strain gauges, are then embedded at the designed elevation. 3) Fixing the tunnel model fixture prepared in step 2) on the model stand; embedding the organic glass plate on the front fixing steel plate (8); 4) Apply load to the test model through the loading system according to the test requirements; 5) Through the data acquisition system, the displacement, applied load and stress data of similar materials and support structures in the test model are monitored and collected in real time, and the test results are analyzed. After obtaining the test results, the test is completed.

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