Simulation device and test method for tunnel excavation stratum loss in high-stress environment
By designing a tunnel excavation formation loss simulation device for high-stress environments, using mechanical expansion and contraction devices and hydraulic control systems, the problem of difficult control of the formation deformation mode and insufficient structural bearing capacity of the existing devices in deep buried and high-stress environments is solved, and accurate simulation and research of tunnel excavation formation losses are achieved.
Patent Information
- Application Number
- CN202510174744.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-18
- Publication Date
- 2025-03-21
- Estimated Expiration
- Not applicable · inactive patent
AI Technical Summary
The existing tunnel excavation simulation device has problems such as difficult to control the formation deformation mode and insufficient structural bearing capacity in deep buried and high stress environments, and it is impossible to accurately simulate the loss of tunnel excavation formations.
A simulating device for tunnel excavation formation loss under high stress environments was designed, and a cylindrical mechanical expansion and contraction device was used to simulate the formation loss caused by tunnel excavation through the movement of horizontal telescopic rods, and the displacement of horizontal telescopic rods was accurately controlled with manual bidirectional hydraulic device.
It realizes effective simulation of tunnel excavation in deep buried high-stress environments, can accurately control the formation loss rate and vertical soil pressure, provides a change curve between the formation loss rate and vertical soil pressure at the tunnel excavation site, and promotes the development of tunnel excavation experimental research.
Smart Images
Figure CN119667119A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of tunnel excavation testing, and in particular to a tunnel excavation stratum loss simulation device and a testing method under a high stress environment. Background Art
[0002] With the increasing development of cities, the utilization of shallow underground space has been close to saturation, and a series of "urban diseases" such as traffic congestion, deteriorating living environment, and resource shortages have become increasingly prominent. In this context, the development of deep underground space has become a "golden key" to solve the urban dilemma. Shield method is an important means of underground space development. In the existing technology, a large number of experimental devices have been manufactured for shield tunnel excavation; however, the tunnel excavation simulation device in the existing technology has a simple structure and can only conduct tunnel excavation model test research under shallow buried low stress conditions. In the deep buried high stress environment, the aforementioned device has the defects of inducing stratum deformation mode and excavation stratum loss cannot be accurately controlled, and the structural bearing capacity is weak. Therefore, in order to meet the needs of deep buried tunnel model tests, it is necessary to design and manufacture tunnel excavation stratum loss simulation devices that can adapt to deep buried high stress environments to promote the development of tunnel excavation test research. Summary of the invention
[0003] In view of the above technical problems, the technical solution adopted by the present invention is: According to a first aspect of the present application, a tunnel excavation test method under a high stress environment is provided, the method comprising the following steps: S100, prepare the soil, model box, loading device and soil pressure gauge required for the test; S200, installing a tunnel excavation stratum loss simulation device inside a model box, setting a soil pressure gauge on the top of the stratum loss simulation device and taking soil samples inside the model box, wherein the tunnel excavation stratum loss simulation device is a cylindrical mechanical expansion and contraction device, which is fixed inside the box; a horizontal telescopic rod is arranged inside the expansion and contraction device, and when the horizontal telescopic rod moves outward, the outer diameter of the expansion and contraction device increases, and when the horizontal telescopic rod moves inward, the outer diameter of the expansion and contraction device decreases; S300: Determine the earth pressure value P based on the distance H between the top of the actual engineering tunnel and the ground surface. s ; S400, P is applied on the surface of the soil in the model box. s Earth pressure; S500, the horizontal telescopic rod is moved inward several times, and the corresponding formation loss rate and the vertical earth pressure of the expansion and contraction device after each movement of the horizontal telescopic rod are obtained to obtain a formation loss rate vertical earth pressure group list A=(A0, A1, ..., A i , …, A N), i=0, 1,...,N; among them, A i is the vertical earth pressure group of the stratum loss rate corresponding to the i-th inward movement of the horizontal telescopic rod, N is the number of horizontal telescopic rod displacements; A i =(A i，1 , A i，2 ); A i，1 is the formation loss rate corresponding to the i-th inward movement of the horizontal telescopic rod, A i，2 is the vertical earth pressure of the expansion and contraction device after the horizontal telescopic rod is moved inward for the i-th time; S600, curve fitting is performed on the stratum loss rate and vertical earth pressure group in A to obtain a curve of the vertical earth pressure corresponding to the tunnel excavation location changing with the stratum loss rate.
[0004] Further, step S500 includes the following steps: S510, initially N=0, the model tunnel diameter is initially set to 250 mm, and the formation loss rate is 0; S520, move the horizontal telescopic rod inward by ΔL, ensuring that the formation loss rate increment after each movement is 0.2%. Then, the formation loss rate corresponding to the Nth inward movement of the horizontal telescopic rod is A N，1 =N×0.2%, the corresponding measured vertical earth pressure on the top of the model tunnel is A N，2 ; S530, obtaining the vertical soil pressure difference ΔF of the horizontal telescopic rod when it moves N times N =A N-1，2 -A N，2 Among them, A 0，2 is the initial vertical earth pressure, A 0，2 =P s ; S540, if ΔF N >ΔF1', then obtain N=N+1; enter S520; wherein ΔF1' is a preset first vertical earth pressure difference threshold; S550, if ΔF2'≤ΔF N ≤ΔF1', then obtain N=N+1; enter S560; wherein ΔF2' is a preset second vertical earth pressure difference threshold; S560, move the horizontal telescopic rod inwards η×ΔL, and obtain the formation loss rate A corresponding to the Nth inward movement of the horizontal telescopic rod N，1 And the vertical earth pressure A of the expansion and contraction device N，2 ; Wherein, η is the preset weight, η>1; S570, if ΔF N <ΔF2', then jump out of the current processing to obtain A.
[0005] Further, the range of ΔL is 0.59 mm to 0.60 mm.
[0006] Furthermore, the expansion and contraction device also includes: an expansion and contraction slider, an expansion and contraction fin and a conical lock core; wherein the conical lock core is connected to the horizontal telescopic rod, and the angle between the conical lock core and the horizontal telescopic rod is 12°; the expansion and contraction slider and the expansion and contraction fins produce horizontal movement together with the horizontal telescopic rod; as the horizontal telescopic rod moves inward, the diameter of the circle at the contact position between the conical lock core and the expansion and contraction slider gradually decreases, thereby increasing the diameter of the external expansion and contraction fin.
[0007] Furthermore, the tunnel excavation stratum loss simulation device also includes a manual bidirectional hydraulic device; wherein the displacement of the horizontal telescopic rod under high stress is accurately controlled by the manual bidirectional hydraulic device.
[0008] According to another aspect of the present application, a device for simulating stratum loss during tunnel excavation under a high stress environment is also provided, the device comprising: a model box and a cylindrical mechanical expansion and contraction device, the cylindrical expansion and contraction device being fixed inside the model box; a horizontal telescopic rod is arranged inside the expansion and contraction device, when the horizontal telescopic rod moves outward, the outer diameter of the expansion and contraction device increases, and when the horizontal telescopic rod moves inward, the outer diameter of the expansion and contraction device decreases.
[0009] Furthermore, the length of the expansion and contraction device is 1250 mm, and the diameter variation range in the contracted state is 250 mm-243.67 mm.
[0010] The present invention has at least the following beneficial effects: The tunnel excavation test method under high stress environment of the present invention is as follows: placing a stratum soil sample at a tunnel excavation site in a preset tunnel excavation stratum loss simulation device, the tunnel excavation stratum loss simulation device comprising a box body and a cylindrical expansion and contraction device, the cylindrical expansion and contraction device being fixed inside the box body; a horizontal telescopic rod is arranged inside the expansion and contraction device, when the horizontal telescopic rod moves outward, the outer diameter of the expansion and contraction device increases, when the horizontal telescopic rod moves inward, the outer diameter of the expansion and contraction device decreases; the horizontal telescopic rod is moved inward several times, and the stratum loss rate and the vertical earth pressure of the expansion and contraction device corresponding to each movement of the horizontal telescopic rod are obtained to obtain a stratum loss rate vertical earth pressure group list; curve fitting is performed on the stratum loss rate and the vertical earth pressure group in the stratum loss rate vertical earth pressure group list to obtain a change curve of the stratum loss rate and the vertical earth pressure corresponding to the tunnel excavation site; thereby the test of tunnel excavation in a deep buried high stress environment is realized relatively simply, the change curve of the stratum loss rate and the vertical earth pressure corresponding to the tunnel excavation site is obtained, and the research and development of tunnel excavation experiments are promoted. BRIEF DESCRIPTION OF THE DRAWINGS
[0011] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.
[0012] Figure 1 A flow chart of a tunnel excavation test method under a high stress environment provided by an embodiment of the present invention; Figure 2 A cross-sectional view of a device for simulating stratum loss during tunnel excavation under a high stress environment provided by an embodiment of the present invention; Figure 3 A side view of a tunnel excavation stratum loss simulation device under a high stress environment provided by an embodiment of the present invention; Description of reference numerals: 100, horizontal telescopic rod, 200, expansion and contraction slider, 300, conical lock core, 400, expansion and contraction fins, 500, flange, d1, length of the first part, d2, length of the second part. DETAILED DESCRIPTION
[0013] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.
[0014] It should be noted that, based on the present disclosure, those skilled in the art should understand that an aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects described herein can be used to implement a device and / or practice a method. In addition, other structures and / or functionalities other than one or more of the aspects described herein can be used to implement this device and / or practice this method.
[0015] The following will refer to Figure 1 The flow chart of the tunnel excavation test method under a high stress environment is shown, which introduces a tunnel excavation test method under a high stress environment.
[0016] The tunnel excavation test method under high stress environment may include the following steps: S100, prepare the soil, model box, loading device and soil pressure gauge required for the test.
[0017] In this embodiment, what is studied is the change of the stratum loss rate and the vertical earth pressure at the specific tunnel excavation site. Therefore, a preset volume of stratum soil samples can be obtained at the actual tunnel excavation site for subsequent testing. It should be noted that the stratum soil at the tunnel excavation site is obtained, and the final change curve of the stratum loss rate and the vertical earth pressure also corresponds to the tunnel excavation site.
[0018] S200, installing a tunnel excavation stratum loss simulation device inside a model box, setting a soil pressure gauge on the top of the stratum loss simulation device and taking soil samples inside the model box, wherein the tunnel excavation stratum loss simulation device is a cylindrical mechanical expansion and contraction device, and the cylindrical mechanical expansion and contraction device is fixed inside the box; a horizontal telescopic rod is arranged inside the expansion and contraction device, and when the horizontal telescopic rod moves outward, the outer diameter of the expansion and contraction device increases, and when the horizontal telescopic rod moves inward, the outer diameter of the expansion and contraction device decreases.
[0019] In this embodiment, a tunnel excavation stratum loss simulation device is preset, and the tunnel excavation stratum loss simulation device includes: a model box and a Figure 2 The cylindrical expansion and contraction device shown is fixed inside the box; a horizontal telescopic rod 100 is arranged inside the expansion and contraction device, and when the horizontal telescopic rod 100 moves outward, the outer diameter of the expansion and contraction device increases, and when the horizontal telescopic rod 100 moves inward, the outer diameter of the expansion and contraction device decreases; the stratum soil sample can be placed in the preset model box, and the expansion and contraction device is buried in the soil, so as to simulate the stratum loss caused by tunnel excavation.
[0020] Furthermore, the expansion and contraction device also includes: an expansion and contraction slider 200, an expansion and contraction fin 400 and a conical lock core 300; wherein, the conical lock core 300 is connected to the horizontal telescopic rod 100, and the angle between the conical lock core 300 and the horizontal telescopic rod 100 is 12°; the expansion and contraction slider 200 and the expansion and contraction fin 400 produce horizontal movement together with the horizontal telescopic rod; as the horizontal telescopic rod moves inward, the diameter of the circle of the contact position between the conical lock core 300 and the expansion and contraction slider 200 gradually increases, so that the diameter of the external expansion and contraction fin increases.
[0021] The specific working principle of the expansion and contraction device is as follows: when the horizontal telescopic rod 100 moves outward, the diameter of the circle at the contact position between the conical lock core 300 and the expansion and contraction slider 200 gradually increases, causing the diameter of the external expansion and contraction fins to increase, thereby achieving overall uniform expansion of the expansion and contraction device; when the horizontal telescopic rod 100 moves inward, the diameter of the circle at the contact position between the conical lock core 300 and the expansion and contraction slider 200 gradually decreases, causing the diameter of the external expansion and contraction fins to decrease, thereby achieving overall uniform contraction of the expansion and contraction device, thereby simulating the stratum loss in tunnel excavation.
[0022] Furthermore, the tunnel excavation stratum loss simulation device also includes a manual bidirectional hydraulic device; wherein the horizontal telescopic rod 100 is connected to the manual bidirectional hydraulic device; and the hydraulic device is used to drive the movement of the horizontal telescopic rod 100.
[0023] Furthermore, the expansion and contraction device is connected to the box body via a flange 500 .
[0024] S300, determining the loading earth pressure value Ps according to the distance H between the top of the actual engineering tunnel and the ground surface; In this embodiment, the distance between the tunnel excavation and the ground surface can be actually measured, and the density of the soil layer at the tunnel excavation can be measured. According to the density of the soil layer at the tunnel excavation and the distance between the tunnel excavation and the ground surface, the loaded earth pressure value can be estimated. It should be noted that those skilled in the art can use the existing earth pressure value calculation method to determine the loaded earth pressure value according to actual needs, which will not be elaborated here.
[0025] S400, P is applied on the surface of the soil in the model box. s of soil pressure.
[0026] In this embodiment, an external loading device may be used to apply a soil pressure of Ps on the surface of the soil in the model box to simulate the soil pressure at the actual tunnel excavation site.
[0027] S500, the horizontal telescopic rod is moved inward several times, and the corresponding formation loss rate and the vertical earth pressure of the expansion and contraction device after each movement of the horizontal telescopic rod are obtained to obtain a formation loss rate vertical earth pressure group list A=(A0, A1, ..., A i , …, A N ), i=0, 1,...,N; among them, A i is the vertical earth pressure group of the stratum loss rate corresponding to the i-th inward movement of the horizontal telescopic rod, N is the number of horizontal telescopic rod displacements; A i =(A i，1 , A i，2 ); A i，1 is the formation loss rate corresponding to the i-th inward movement of the horizontal telescopic rod, A i，2 is the vertical soil pressure of the expansion and contraction device after the horizontal telescopic rod is moved inward for the i-th time.
[0028] Further, step S500 may include the following steps: S510, initially N=0, the model tunnel diameter is initially set to 250 mm, and the formation loss rate is 0.
[0029] S520, move the horizontal telescopic rod inward by ΔL, ensuring that the formation loss rate increment after each movement is 0.2%. Then, the formation loss rate corresponding to the Nth inward movement of the horizontal telescopic rod is A N，1=N×0.2%, the corresponding measured vertical earth pressure on the top of the model tunnel is A N，2 .
[0030] In this embodiment, the horizontal telescopic rod is moved inward by ΔL, and the diameter of the expansion and contraction device will decrease. At this time, the corresponding formation loss rate A can be calculated. N，1 And the vertical earth pressure A of the expansion and contraction device N，2 It should be noted that those skilled in the art can use the existing formation loss rate and vertical earth pressure calculation method to calculate the formation loss rate A corresponding to the Nth inward movement of the horizontal telescopic rod. N，1 And the vertical earth pressure A of the expansion and contraction device N，2 , which will not be elaborated here.
[0031] Furthermore, the value range of ΔL is 0.59 mm to 0.60 mm.
[0032] S530, obtaining the vertical soil pressure difference ΔF of the horizontal telescopic rod when it moves N times N =A N-1，2 -A N，2 Among them, A 0，2 is the initial vertical earth pressure, A 0，2 =P s .
[0033] In this embodiment, as the horizontal telescopic rod in the expansion and contraction device gradually moves inward, the diameter of the expansion and contraction device gradually decreases, and accordingly, the vertical soil pressure value also gradually decreases. Therefore, the vertical soil pressure difference ΔF corresponding to two adjacent movements of the horizontal telescopic rod can be obtained. N .
[0034] S540, if ΔF N >ΔF1', then obtain N=N+1; enter S520; wherein ΔF1' is a preset first vertical earth pressure difference threshold.
[0035] In this embodiment, if ΔF N >ΔF1', indicating that after the N-th movement of the horizontal telescopic rod, the corresponding N-th vertical soil pressure difference is still large. At this time, the soil layer is not in a relatively stable state; therefore, the horizontal telescopic rod continues to be moved inward at a smaller ΔL.
[0036] S550, if ΔF2'≤ΔF N ≤ΔF1', then obtain N=N+1; proceed to S560; wherein ΔF2' is a preset second vertical earth pressure difference threshold.
[0037] In this embodiment, if ΔF2'≤ΔF N≤ΔF1', it means that after the N-th movement of the horizontal telescopic rod, the corresponding N-th vertical soil pressure difference is already small, and at this time, the soil layer is already in a relatively stable state; therefore, enter S560 to increase the step length of the horizontal telescopic rod movement to improve the test efficiency.
[0038] S560, move the horizontal telescopic rod inwards η×ΔL, and obtain the formation loss rate A corresponding to the Nth inward movement of the horizontal telescopic rod N，1 And the vertical earth pressure A of the expansion and contraction device N，2 ; Wherein, η is the preset weight, η>1.
[0039] In this embodiment, the value range of η is 1.5 to 2; for example: η=1.8; when the soil layer is in a relatively stable state, increasing the distance that the horizontal telescopic rod moves each time can obtain the final test result as soon as possible, thereby improving the test efficiency.
[0040] S570, if ΔF N <ΔF2', then jump out of the current processing to obtain A.
[0041] In this embodiment, if ΔF N <ΔF2', it means that after the N-th movement of the horizontal telescopic rod, the corresponding N-th vertical soil pressure difference hardly changes, and the soil layer is already in a stable state; at this time, the current processing can be skipped to obtain A.
[0042] S600, curve fitting is performed on the stratum loss rate and vertical earth pressure group in A to obtain a curve of the vertical earth pressure corresponding to the tunnel excavation location changing with the stratum loss rate.
[0043] In this embodiment, after obtaining A, the data in A can be curve fitted to obtain a variation curve of the stratum loss rate and the vertical earth pressure corresponding to the tunnel excavation; during actual tunnel excavation, the variation curve can be used as a reference to select other equipment or set corresponding parameters; it should be noted that those skilled in the art can use existing curve fitting methods to perform curve fitting on the data in A to obtain a variation curve of the stratum loss rate and the vertical earth pressure corresponding to the tunnel excavation, which will not be elaborated here.
[0044] The tunnel excavation stratum loss simulation device and test method under high stress environment of this embodiment are as follows: the stratum soil at the tunnel excavation site is placed in a preset tunnel excavation stratum loss simulation device, the tunnel excavation stratum loss simulation device comprises a model box and a cylindrical expansion and contraction device, the cylindrical expansion and contraction device is fixed inside the box; a horizontal telescopic rod is arranged inside the expansion and contraction device, when the horizontal telescopic rod moves outward, the outer diameter of the expansion and contraction device increases, when the horizontal telescopic rod moves inward, the outer diameter of the expansion and contraction device decreases; the horizontal telescopic rod is moved inward several times, and The formation loss rate corresponding to each movement of the horizontal telescopic rod and the vertical earth pressure of the expansion and contraction device are obtained to obtain a formation loss rate and vertical earth pressure group list; the formation loss rate and vertical earth pressure group in the formation loss rate and vertical earth pressure group list are curve fitted to obtain the change curve of the formation loss rate and vertical earth pressure corresponding to the tunnel excavation; thereby, the test of the tunnel load of the tunnel excavation in a deep buried high stress environment is relatively simple, and the change curve of the formation loss rate and vertical earth pressure corresponding to the tunnel excavation is obtained, which promotes the development of tunnel excavation test research.
[0045] In an exemplary embodiment, a tunnel excavation stratum loss simulation device under a high stress environment is also provided, the device comprising: a box and Figure 2 and Figure 3 The cylindrical expansion and contraction device shown is fixed inside the box; a horizontal telescopic rod 100 is arranged inside the expansion and contraction device. When the horizontal telescopic rod 100 moves outward, the outer diameter of the expansion and contraction device increases, and when the horizontal telescopic rod 100 moves inward, the outer diameter of the expansion and contraction device decreases.
[0046] In this embodiment, a tunnel excavation stratum loss simulation device is preset, and the device includes: a box and Figure 2 The cylindrical expansion and contraction device shown in the figure is fixed inside the box; a horizontal telescopic rod 100 is arranged inside the expansion and contraction device, and when the horizontal telescopic rod 100 moves outward, the outer diameter of the expansion and contraction device increases, and when the horizontal telescopic rod 100 moves inward, the outer diameter of the expansion and contraction device decreases; the stratum soil can be placed in a preset tunnel excavation stratum loss simulation device soil box, and the expansion and contraction device is buried in the soil, so as to simulate the stratum loss caused by tunnel excavation.
[0047] Furthermore, the expansion and contraction device also includes: an expansion and contraction slider 200, an expansion and contraction fin 400 and a conical lock core 300; wherein, the conical lock core 300 is connected to the horizontal telescopic rod 100, and the angle between the conical lock core 300 and the horizontal telescopic rod 100 is 12°; the expansion and contraction slider 200 and the expansion and contraction fin 400 produce horizontal movement together with the horizontal telescopic rod; the diameter of the circle at the contact position between the conical lock core 300 and the expansion and contraction slider 200 gradually increases, so that the diameter of the external expansion and contraction fin increases.
[0048] The specific working principle of the expansion and contraction device is as follows: when the horizontal telescopic rod 100 moves outward, the diameter of the circle at the contact position between the conical lock core 300 and the expansion and contraction slider 200 gradually increases, causing the diameter of the external expansion and contraction fins to increase, thereby achieving overall uniform expansion of the expansion and contraction device; when the horizontal telescopic rod 100 moves inward, the diameter of the circle at the contact position between the conical lock core 300 and the expansion and contraction slider 200 gradually decreases, causing the diameter of the external expansion and contraction fins to decrease, thereby achieving overall uniform contraction of the expansion and contraction device, thereby simulating the stratum loss in tunnel excavation.
[0049] Furthermore, the tunnel excavation stratum loss simulation device also includes a manual bidirectional hydraulic device; wherein the horizontal telescopic rod 100 is connected to the manual bidirectional hydraulic device; and the hydraulic device is used to drive the movement of the horizontal telescopic rod 100.
[0050] Furthermore, the expansion and contraction device is connected to the box body via a flange 500 .
[0051] Furthermore, the expansion and contraction device includes two parts, the length of the first part is d1 = 1000 mm, and the length of the second part is d2 = 250 mm.
[0052] The following is a specific example: the tunnel excavation stratum loss simulation device in the above embodiment is installed inside the box to conduct a tunnel excavation model test. The initial diameter of the expansion and contraction device (model tunnel) is set to 0.25m, the bottom of the model tunnel is 0.25m away from the bottom of the model box, and the top of the fill is 0.55m away from the top of the model tunnel. The soil weight is 15.77kN / m 3 , the initial porosity ratio is 0.671.
[0053] Top loading earth pressure P s The pressure is 779.8 kPa, which is applied by the loading device to simulate tunnel excavation under the stress environment of 50 m burial depth. During the test, the hydraulic source is used to drive the horizontal telescopic rod of the tunnel excavation stratum loss simulation device to move inward, causing the diameter of the model tunnel to gradually decrease to simulate the stratum loss of tunnel excavation, and the curve of the change of the overburden pressure on the tunnel with the increase of stratum loss rate is obtained.
[0054] In addition, although the steps of the method in the present disclosure are described in a specific order in the drawings, this does not require or imply that the steps must be performed in this specific order, or that all the steps shown must be performed to achieve the desired results. Additionally or alternatively, some steps may be omitted, multiple steps may be combined into one step, and / or one step may be decomposed into multiple steps, etc.
Claims
1. A tunnel excavation test method under high stress environment, characterized in that: The method comprises the following steps: S100, prepare the soil, model box, loading device and soil pressure gauge required for the test; S200, installing a tunnel excavation stratum loss simulation device inside a model box, setting a soil pressure gauge on the top of the stratum loss simulation device and taking soil samples inside the model box, wherein the tunnel excavation stratum loss simulation device is a cylindrical mechanical expansion and contraction device, which is fixed inside the box; a horizontal telescopic rod is arranged inside the expansion and contraction device, and when the horizontal telescopic rod moves outward, the outer diameter of the expansion and contraction device increases, and when the horizontal telescopic rod moves inward, the outer diameter of the expansion and contraction device decreases; S300: Determine the earth pressure value P based on the distance H between the top of the actual engineering tunnel and the ground surface. s ; S400, P is applied on the surface of the soil in the model box. s Earth pressure; S500, the horizontal telescopic rod is moved inward several times, and the corresponding formation loss rate and the vertical earth pressure of the expansion and contraction device after each movement of the horizontal telescopic rod are obtained to obtain a formation loss rate vertical earth pressure group list A=(A0, A1, ..., A i , …, A N ), i=0, 1,...,N; among them, A i is the vertical earth pressure group of the stratum loss rate corresponding to the i-th inward movement of the horizontal telescopic rod, N is the number of horizontal telescopic rod displacements; A i =(A i，1 , A i，2 ); A i，1 is the formation loss rate corresponding to the i-th inward movement of the horizontal telescopic rod, A i，2 is the vertical earth pressure of the expansion and contraction device after the horizontal telescopic rod is moved inward for the i-th time; S600, curve fitting is performed on the stratum loss rate and vertical earth pressure group in A to obtain a curve of the vertical earth pressure corresponding to the tunnel excavation location changing with the stratum loss rate.
2. The tunnel excavation test method under high stress environment according to claim 1, characterized in that: Step S500 includes the following steps: S510, initially N=0, the model tunnel diameter is initially set to 250 mm, and the formation loss rate is 0; S520, move the horizontal telescopic rod inward by ΔL, ensuring that the formation loss rate increment after each movement is 0.2%. Then, the formation loss rate corresponding to the Nth inward movement of the horizontal telescopic rod is A N，1 =N×0.2%, the corresponding measured vertical earth pressure on the top of the model tunnel is A N，2 ; S530, obtaining the vertical soil pressure difference ΔF of the horizontal telescopic rod when it moves N times N =A N-1，2 -A N，2 Among them, A 0，2 is the initial vertical earth pressure, A 0，2 =P s ; S540, if ΔF N >ΔF1', then obtain N=N+1; enter S520; wherein ΔF1' is a preset first vertical earth pressure difference threshold; S550, if ΔF2'≤ΔF N ≤ΔF1', then obtain N=N+1; enter S560; wherein ΔF2' is a preset second vertical earth pressure difference threshold; S560, move the horizontal telescopic rod inwards η×ΔL, and obtain the formation loss rate A corresponding to the Nth inward movement of the horizontal telescopic rod N，1 And the vertical earth pressure A of the expansion and contraction device N，2 ; Wherein, η is the preset weight, η>1; S570, if ΔF N <ΔF2', then jump out of the current processing to obtain A.
3. The tunnel excavation test method under high stress environment according to claim 2, characterized in that: The range of ΔL is 0.59 mm to 0.60 mm.
4. The tunnel excavation test method under high stress environment according to claim 1, characterized in that: The expansion and contraction device also includes: an expansion and contraction slider, an expansion and contraction fin and a conical lock core; wherein the conical lock core is connected to the horizontal telescopic rod, and the angle between the conical lock core and the horizontal telescopic rod is 12°; the expansion and contraction slider and the expansion and contraction fins produce horizontal movement together with the horizontal telescopic rod; as the horizontal telescopic rod moves inward, the diameter of the circle at the contact position between the conical lock core and the expansion and contraction slider gradually decreases, so that the diameter of the external expansion and contraction fin increases.
5. The tunnel excavation test method under high stress environment according to claim 1, characterized in that: The tunnel excavation stratum loss simulation device also includes a manual bidirectional hydraulic device; wherein the displacement of the horizontal telescopic rod under high stress is accurately controlled by the manual bidirectional hydraulic device.
6. A device for simulating stratum loss during tunnel excavation under high stress environment, characterized in that: The device comprises: a model box and a cylindrical mechanical expansion and contraction device, wherein the cylindrical expansion and contraction device is fixed inside the model box; a horizontal telescopic rod is arranged inside the expansion and contraction device, when the horizontal telescopic rod moves outward, the outer diameter of the expansion and contraction device increases, and when the horizontal telescopic rod moves inward, the outer diameter of the expansion and contraction device decreases.
7. The device for simulating stratum loss during tunnel excavation under high stress environment according to claim 6, characterized in that: The length of the expansion and contraction device is 1250 mm, and the diameter variation range in the contracted state is 250 mm-243.67 mm.