Pre-deformation controlled self-servo steel arch and construction method thereof

Abstract

The invention discloses a pre-deformation controlled self-servo steel arch and a construction method thereof. The pre-deformation controlled self-servo steel arch comprises a socket sleeve, an inserting sleeve, a limiting lantern ring, a bearing plate, a hydraulic spring and a steel arch body. The socket sleeve, the inserting sleeve and the hydraulic spring are coaxially arranged and then located on the two sides of the circular tunnel steel arch frame, and the axes of the socket sleeve, the inserting sleeve and the hydraulic spring are perpendicular to the inverted arch face; the socket sleeve and the insertion sleeve are respectively fixed on the steel arch frame, the socket sleeve and the insertion sleeve are mutually inserted, one end of the insertion sleeve, which is positioned on the socket sleeve, is provided with the bearing plate, the hydraulic spring is positioned between the bearing plate and the socket sleeve, and the insertion sleeve is sleeved with the limiting lantern ring. According to the invention, a flexible and controllable self-adaptive mechanism based on the axial force and the deformation is provided, and the situations that the surrounding rock is rapidly unloaded, the stress is released and the deformation is difficult to control under the condition of no support are reduced to a certain extent.

Description

Technical Field

[0001] The present invention relates to the technical field of tunnel support, and specifically to a self-servo steel arch with pre-deformation control and its construction method. Background Art

[0002] Tunnel engineering is an important construction stage in road traffic construction. During tunnel construction, it is necessary to use arch frames for the initial support of the tunnel to ensure the safety and stability of tunnel construction.

[0003] The following problems exist at the present stage:

[0004] 1. Traditional tunnel support is immediately carried out after excavation, which is likely to cause the steel arch to suddenly bear excessive force and yield and fail.

[0005] 2. The optimal support timing theory of the New Austrian Tunneling Method is difficult to implement in the field of engineering applications, and the adjustability of the reserved deformation amount is poor.

[0006] 3. The delayed support method has the risk of sudden unloading of the surrounding rock, stress release, and excessive growth of the deformation amount, which is difficult to control, and there are no effective engineering control measures before the time point of delayed support. Summary of the Invention

[0007] The purpose of the present invention is to provide a self-servo steel arch with pre-deformation control and its construction method to solve the problems in the prior art.

[0008] To achieve the above purpose, the present invention provides the following technical solution: A self-servo steel arch with pre-deformation control, comprising a socket sleeve, a plug sleeve, a limit collar, a bearing plate, a hydraulic spring, and a steel arch;

[0009] The socket sleeve, the plug sleeve, and the hydraulic spring are coaxially arranged. After the socket sleeve, the plug sleeve, and the hydraulic spring are coaxially arranged, they are located on both sides of the circular tunnel steel arch, and the axes of the socket sleeve, the plug sleeve, and the hydraulic spring are perpendicular to the invert surface;

[0010] The socket sleeve and the plug sleeve are respectively fixed on the steel arch. The socket sleeve and the plug sleeve are inserted into each other. A bearing plate is installed at one end of the plug sleeve, the hydraulic spring is located between the bearing plate and the socket sleeve, and a limit collar is sleeved on the plug sleeve.

[0011] Preferably, the socket sleeve is provided with a slot, the plug sleeve is provided with a plug that cooperates with the slot, the bearing plate is located at one end of the plug, the hydraulic spring is located in the slot, and the limit collar is sleeved on the plug.

[0012] Preferably, it further includes an axial force control device and a hydraulic controller. There are gaps at the arch waist positions on both sides of the steel arch. The axial force control device is installed at the gaps of the steel arch. An axial force sensor is installed at the axial position inside the steel arch. The controller is respectively connected to the hydraulic spring and the axial force sensor.

[0013] Preferably, the axial force control device is coaxial with the steel arch.

[0014] A construction method of a self - servo steel arch with pre - deformation control uses the self - servo steel arch with pre - deformation control as described above. It includes the following steps:

[0015] S1. Tunnel surrounding rock geological data: Collect the geological data of the surrounding rock at the tunnel section of the application point, and sort out and analyze the in - situ stress conditions, the physical and mechanical properties of the surrounding rock, and the tunnel support structure drawings.

[0016] S2. Finite element calculation by elastic modulus reduction method: Establish a three - dimensional finite element model of the tunnel surrounding rock and the support structure, divide the grid, assign material properties, boundary conditions, and initial conditions to the finite element model, and the values conform to the actual situation of the application point; Reduce the elastic modulus of the tunnel surrounding rock to simulate the tunnel excavation unloading process. During multiple trial calculations, count the numerical values of the surrounding rock deformation, plastic zone distribution, and the force on the support structure, and select the optimal support timing condition from multiple working conditions.

[0017] S3. After obtaining the reserved deformation amount of the surrounding rock and the axial force load value of the steel arch under the optimal support timing from the calculation in S2, design the opening distance Sc between the limit sleeve ring and the socket sleeve ring of the axial force control device and the elastic force value F of the hydraulic spring min ;

[0018] S4. Prefabrication of the steel arch axial force control device: Prefabricate the steel arch and the axial force control device according to the design values in S3.

[0019] S5. Assembly of the steel arch and installation of the axial force control device: Keep the axial force control device installed on both sides of the steel arch and keep the axis perpendicular to the invert surface.

[0020] S6. Monitoring of the steel arch axial force: Start the hydraulic device to pressurize the hydraulic spring, observe the axial force sensor of the steel arch, and control the axial force of the steel arch to remain at the value of F min unchanged during the compression process;

[0021] S7. Deformation reaches the reserved deformation amount: The surrounding rock continues to deform until the socket sleeve contacts the limit sleeve, that is, the ideal state of the optimal support timing is reached. At this time, the self - servo steel arch enters the rigid support stage.

[0022] S8. Removal of the axial force control device: After the hydraulic device is depressurized, take out the hydraulic spring, which can be recycled at the next application point.

[0023] A construction method of a self - servo steel arch with pre - deformation control according to claim 5, characterized in that the forces on the support structure in S2 include the axial force of the steel arch, the shotcrete of the primary support, and the tensile stress of the anchor bolts.

[0024] Preferably, the forces on the support structure in S2 include the axial force of the steel arch, the shotcrete of the primary support, and the tensile stress of the anchor bolts.

[0025] Preferably, the optimal support timing in S2 is after the surrounding rock has undergone a certain amount of deformation and exerted its maximum bearing capacity, and at the same time, it satisfies that the axial force of the steel arch is the smallest, the tensile force of the anchor bolts is in a relatively small state, the compressive stress of the shotcrete of the primary lining is less than the compressive strength of the concrete, and the range of the plastic zone of the surrounding rock is less than the length of the anchor bolts.

[0026] Preferably, after the blasting excavation is completed at the application point in S5, the assembly of the steel arch needs to be constructed immediately, and the axial force control device needs to be installed.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] 1. The view of giving full play to the self - bearing capacity of the surrounding rock is fully considered, and on this basis, the support time is advanced, and an adaptive mechanism that is flexibly controllable based on the axial force and deformation is proposed, which reduces to a certain extent the situation where the surrounding rock unloads rapidly, the stress is released, and the deformation is difficult to control without support.

[0029] 2. Compared with the traditional support method, the present invention avoids the instantaneous stress concentration on the support structure in the case of immediate support after excavation, and reduces the possibility of concrete spalling and yield failure of the steel arch.

[0030] 3. Compared with the flexible support method for large - deformation soft - rock tunnel sections, the adjustability of its flexible space is poor, it is difficult to implement observation and control, and its applicability to different construction conditions is poor. The present invention proposes an intelligent support method that is controllable based on the axial force of the steel arch and the deformation of the surrounding rock. The control device is detachable and can be reused, and it is applicable not only to large - deformation soft - rock sections but also to other tunnel support situations. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The drawings are used to provide a further understanding of the present invention, and constitute a part of the specification. They are used together with the embodiments of the present invention to explain the present invention, and do not constitute a limitation to the present invention. In the drawings:

[0032] Figure 1 is a schematic structural diagram of the present invention;

[0033] Figure 2 is a schematic structural diagram of the socket sleeve and the inserted sleeve of the present invention;

[0034] Figure 3 It is the schematic diagram of the control of the present invention;

[0035] Figure 4 It is the relationship curve diagram of the surrounding rock deformation, the action of the surrounding rock and the support load pressure of the present invention;

[0036] Figure 5 It is the relationship curve diagram of the surrounding rock deformation and the stress of the support structure of the present invention.

[0037] In the figure: 1. Inverted arch; 2. Axial force control device; 3. Steel arch frame; 4. Axial force sensor; 6. Hydraulic controller; 7. Bearing plate; 8. Plugging sleeve; 9. Limit collar; 10. Hydraulic spring; 11. Socket sleeve. Specific embodiments

[0038] 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 with reference to the accompanying 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. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention. 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 present invention, but merely represents the selected embodiments of the present invention.

[0039] Such as Figure 4-5 , the self - servo system of the steel arch frame with pre - deformation control

[0040] (1) Optimization of the optimal support timing of the New Austrian Tunneling Method:

[0041] The theoretical basis of the New Austrian Tunneling Method is to maximize the self - bearing capacity of the surrounding rock. The self - bearing capacity of the surrounding rock is closely related to the surrounding rock characteristics, in - situ stress, the mechanical characteristics of the support structure, etc. For the surrounding rock with determined lithology and rock mass structure, there is a certain law between the self - bearing capacity of the surrounding rock and the deformation of the surrounding rock. The relationship curve of the surrounding rock deformation, the action of the surrounding rock and the support load pressure as shown in Figure 4 can be obtained. The ordinate represents the support force, and the abscissa represents the surrounding rock deformation. It can be seen that as the surrounding rock deformation increases, the support force decreases continuously in the first stage and then gradually increases in the second stage. There is a minimum value between the two stages, which is the point where the surrounding rock exerts the maximum self - bearing capacity, that is, the optimal support timing described in the New Austrian Tunneling Method.

[0042] Therefore, the steel arch is the first line of defense against surrounding rock pressure. The view of the New Austrian Tunneling Method's flexible support theory is to "yield" first and then "resist", that is, to allow the surrounding rock to deform to a certain extent and then resist the continuous growth of the deformation. However, for sections with poor surrounding rock conditions, especially large deformation sections in soft rock, the initial "yielding" has the risk of causing the surrounding rock to deform too quickly after unloading, resulting in excessive deformation that is difficult to control. The present invention proposes an optimized method for the optimal support timing of the New Austrian Tunneling Method, and a self-servo system of the steel arch is provided to achieve this process:

[0043] 1) Calculate the minimum value of the surrounding rock pressure (F min ) and the reserved deformation amount of the surrounding rock (S c ) for the optimal support timing of the New Austrian Tunneling Method;

[0044] 2) Adopt the self-servo system of the steel arch. Immediately after blasting excavation, support the steel arch. The distance between the limit collar and the top of the socket sleeve of the axial force control device of the steel arch is set as Sc;

[0045] 3) Set the elastic force of the hydraulic spring in the axial force control device as F min , and start the compression process of the hydraulic spring;

[0046] 4) After the hydraulic spring is compressed by a displacement of S c , the optimal support timing of the New Austrian Tunneling Method theory is reached.

[0047] (2) Calculation of the reserved deformation amount and the axial force of the steel arch

[0048] The value of the reserved deformation amount of the surrounding rock depends on the tunnel depth, in-situ stress, physical and mechanical properties of the rock mass itself, etc. The "Code for Design of Highway Tunnels" (JTG D70 / 2-2014) recommends estimating the value of the reserved deformation amount according to the engineering analogy method; the "Code for Design of Railway Tunnels" (TB10003-2016) recommends estimating the reserved deformation amount according to the surrounding rock grade and span type. In order to obtain a more accurate reserved deformation amount closer to the actual situation, the present invention adopts the establishment of a three-dimensional finite element model of the tunnel surrounding rock and the support structure, assigns values according to the actual in-situ stress and physical and mechanical properties of the surrounding rock, and uses the method of reducing the elastic modulus of the surrounding rock to calculate the relationship curve between the surrounding rock deformation and the support structure force; then, based on comprehensive factors such as the force of the shotcrete in the primary lining, the axial force of the steel arch, the force of the bolt, and the distribution of the plastic zone of the surrounding rock, the surrounding rock deformation amount and the support force at the optimal support timing are determined, that is, the reserved deformation amount and the axial force of the steel arch under the optimal support timing described in the present invention. The calculation process will not be elaborated.

[0049] Please refer to Figures 1-3 , in the embodiment of the present invention, a self-servo steel arch with pre-deformation control includes a socket sleeve 11, a plug sleeve 8, a limit collar 9, a bearing plate 7, a hydraulic spring 10, and a steel arch 3;

[0050] The socket sleeve 11, the plug sleeve 8 and the hydraulic spring 10 are coaxially arranged. After the socket sleeve 11, the plug sleeve 8 and the hydraulic spring 10 are coaxially arranged, they are located on both sides of the circular tunnel steel arch 3, and the axes of the socket sleeve 11, the plug sleeve 8 and the hydraulic spring 10 are perpendicular to the invert 1 surface;

[0051] The socket sleeve 11 and the plug sleeve 8 are respectively fixed on the steel arch 3. The socket sleeve 11 and the plug sleeve 8 are inserted into each other. A bearing plate 7 is installed at one end of the plug sleeve 8 where it is located in the socket sleeve 11. The hydraulic spring 10 is located between the bearing plate 7 and the socket sleeve 11. A limit collar 9 is sleeved on the plug sleeve 8; The socket sleeve 11 is provided with a slot, the plug sleeve 8 is provided with a plug that matches the slot, the bearing plate 7 is located at one end of the plug, and the hydraulic spring 10 is located in the slot. The limit collar 9 is sleeved on the plug.

[0052] It also includes an axial force control device 2 and a hydraulic controller 6. There is a gap at the waist position on both sides of the steel arch 3. The axial force control device 2 is installed at the gap of the steel arch 3. An axial force sensor 4 is installed at the axial position inside the steel arch 3. The controller is respectively connected to the hydraulic spring 10 and the axial force sensor 4; The axial force control device 2 is coaxial with the steel arch 3.

[0053] Self - servo steel arch system:

[0054] (1) System design:

[0055] After calculating the reserved deformation amount of the tunnel surrounding rock and the axial force of the steel arch under a certain working condition based on the optimal support timing theory of the New Austrian Tunneling Method, the self - servo steel arch system described in the present invention can be used to realize this application process. The self - servo steel arch system includes: a socket sleeve, a plug sleeve, a limit collar, a bearing plate, a hydraulic spring and a steel arch. The socket sleeve, the plug sleeve and the hydraulic spring are coaxially arranged and are located on both sides of the circular tunnel steel arch, and their axes are perpendicular to the invert surface. The two ends of the socket sleeve and the plug sleeve are connected to the steel arch with bolt bases.

[0056] The socket sleeve installed on the steel arch has an installation end and an open end, and is provided with a pick - up hole communicating with the inner cavity of the socket sleeve.

[0057] The plug sleeve also has an open end and an installation end. Its open end is movably inserted into the open end of the socket sleeve, and there is a gap between the outer wall of the open end and the inner wall of the open end of the socket sleeve. A bearing plate is installed inside the open end of the plug sleeve.

[0058] The hydraulic spring is arranged inside the socket sleeve and is detachably supported between the bearing plate and the first installation end.

[0059] The limit collar is sleeved on the installation end of the insertion sleeve in a position-adjustable manner and abuts against the end face of the opening end of the socket sleeve.

[0060] (2) System control:

[0061] On the same steel arch, gaps are provided at the positions of the two side arch waists. The axial force control device of the steel arch is located in this secondary gap and is coaxial with the steel arch. The socket sleeve is installed on the steel arch at the lower end of this gap, and the insertion sleeve is installed on the steel arch at the upper end of this gap. An axial force sensor is installed at the axial position inside the steel arch to collect the axial force value of the steel arch. The controller is connected to the hydraulic spring and the axial force sensor and can control the compression of the hydraulic spring. The hydraulic spring supports the socket sleeve to apply an axial top force to the steel arch. Adjust the compression of the controller and the hydraulic spring so that the elastic force of the hydraulic spring remains at F min , and continue this compression process. When the compression continues until the limit collar abuts against the end face of the socket sleeve, the controller controls to close the contraction of the hydraulic spring. After the contraction of the hydraulic spring is completed, the hydraulic spring is taken out through the pick-up hole.

[0062] A construction method for a self-servo steel arch with pre-deformation control uses the self-servo steel arch with pre-deformation control as described above; it includes the following steps:

[0063] S1. Tunnel surrounding rock geological data: Collect the surrounding rock geological data of the tunnel section at the application point, and sort out and analyze the in-situ stress situation, the physical and mechanical properties of the surrounding rock, and the tunnel support structure drawings.

[0064] S2. Finite element calculation by elastic modulus reduction method: Establish a three-dimensional finite element model of the tunnel surrounding rock and the support structure, divide the grid, assign material properties, boundary conditions, and initial conditions to the finite element model, and the values conform to the actual situation of the application point; reduce the elastic modulus of the tunnel surrounding rock to simulate the tunnel excavation unloading process, and count the numerical values of the surrounding rock deformation, plastic zone distribution, and support structure force during multiple trial calculations, and select the optimal support timing condition from multiple working conditions; the support structure force in S2 includes the axial force of the steel arch 3, the primary support shotcrete, and the bolt tensile stress; the optimal support timing in S2 is after the surrounding rock has a certain deformation and exerts its maximum bearing capacity, and at the same time, it meets the conditions that the axial force of the steel arch 3 is the smallest, the bolt tension is in a relatively small state, the compressive stress of the primary lining shotcrete is less than the concrete compressive strength, and the range of the surrounding rock plastic zone is less than the bolt length.

[0065] S3. After obtaining the reserved deformation amount of the surrounding rock and the axial force load value of the steel arch 3 under the optimal support timing from the calculation in S2, design the distance S c between the limit collar 9 of the axial force control device 2 and the opening of the socket collar, and the elastic force value F min of the hydraulic spring 10;

[0066] S4. Prefabrication of the axial force control device 2 for the steel arch 3: Prefabricate the steel arch 3 and the axial force control device 2 according to the design values in S3;

[0067] S5. Assembly of the steel arch 3 and installation of the axial force control device 2: Keep the axial force control device 2 installed on both sides of the steel arch 3 and keep the axis perpendicular to the invert 1 surface; After the blasting excavation is completed at the application point in S5, it is necessary to immediately construct the assembly of the steel arch 3 and install the axial force control device 2;

[0068] S6. Axial force monitoring of the steel arch 3: Start the hydraulic device to pressurize the hydraulic spring 10, observe the axial force sensor 4 of the steel arch 3, and control the axial force of the steel arch 3 to remain at F min unchanged during the compression process;

[0069] S7. Deformation reaches the reserved deformation amount: The surrounding rock continues to deform until the socket casing 11 contacts the limit casing, that is, the ideal state of the optimal support timing is reached. At this time, the self - servo steel arch 3 enters the rigid support stage;

[0070] S8. Removal of the axial force control device 2: After the hydraulic device is depressurized, take out the hydraulic spring 10, which can be recycled at the next application point.

[0071] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A self-servo steel arch frame with pre-deformation control, characterized in that: It comprises a socket sleeve (11), a plug sleeve (8), a limiting collar (9), a pressure plate (7), a hydraulic spring (10) and a steel arch frame (3); The socket sleeve (11), the splice sleeve (8) and the hydraulic spring (10) are coaxially arranged, and the socket sleeve (11), the splice sleeve (8) and the hydraulic spring (10) are coaxially arranged and located at both sides of the circular tunnel steel arch frame (3), and the axes of the socket sleeve (11), the splice sleeve (8) and the hydraulic spring (10) are perpendicular to the surface of the inverted arch (1); The bell-and-spigot sleeve (11) and the plug-in sleeve (8) are respectively fixed on the steel arch frame (3); the bell-and-spigot sleeve (11) and the plug-in sleeve (8) are plugged into each other; the plug-in sleeve (8) is located at one end of the bell-and-spigot sleeve (11) and is provided with a pressure plate (7); the hydraulic spring (10) is located between the pressure plate (7) and the bell-and-spigot sleeve (11); and a limiting collar (9) is sleeved on the plug-in sleeve (8).

2. A self-servo steel arch with pre-deformation control according to claim 1, characterized in that: The socket sleeve (11) is provided with a slot, the plug sleeve (8) is provided with a plug that matches the slot, the pressure plate (7) is located at one end of the plug, and the hydraulic spring (10) is located in the slot, and the limiting ring (9) is sleeved on the plug.

3. A self-servo steel arch with pre-deformation control according to claim 2, characterized in that: It also includes an axial force control device (2) and a hydraulic controller (6); gaps are provided at the waist positions on both sides of the steel arch frame (3); the axial force control device (2) is installed at the gaps of the steel arch frame (3); an axial force sensor (4) is installed at the axial position in the steel arch frame (3); and the controller is respectively connected to the hydraulic spring (10) and the axial force sensor (4).

4. The self-servo steel arch frame with pre-deformation control according to claim 3, characterized in that: The axial force control device (2) is coaxial with the steel arch frame (3).

5. A construction method of a self-servo steel arch frame with pre-deformation control, characterized in that: A self-servo steel arch frame with pre-deformation control according to any one of claims 1 to 4 is used; comprising the following steps: S1. Tunnel surrounding rock geological data: Collect the surrounding rock geological data of the tunnel section at the application point, and organize and analyze the local ground stress conditions, physical and mechanical properties of the surrounding rock, and tunnel support structure drawings; S2. Finite element calculation using elastic modulus reduction method: Establish a three-dimensional finite element model of the tunnel surrounding rock and support structure, divide the grid, assign values ​​to the material properties, boundary conditions, and initial conditions of the finite element model, and select values ​​that conform to the actual situation at the application point; reduce the elastic modulus of the tunnel surrounding rock to simulate the tunnel excavation unloading process, and statistically calculate the surrounding rock deformation, plastic zone distribution, and support structure stress values ​​in multiple groups of trial calculations, and select the optimal support timing condition from multiple groups of working conditions; S3, after calculating the reserved deformation of the surrounding rock and the axial load value of the steel arch frame (3) at the optimal support time by S2, the opening distance S between the limit ring (9) and the socket ring of the axial force control device (2) is designed. c 、Hydraulic spring (10) elastic value F min ; S4, prefabrication of the steel arch frame (3) axial force control device (2): prefabricate the steel arch frame (3) and the axial force control device (2) according to the design value of S3; S5, assembling the steel arch frame (3) and installing the axial force control device (2): keep the axial force control device (2) installed on both sides of the steel arch frame (3), and keep the axis perpendicular to the surface of the inverted arch (1); S6. Axial force monitoring of the steel arch frame (3): start the hydraulic device to pressurize the hydraulic spring (10), observe the axial force sensor (4) of the steel arch frame (3), and control the axial force of the steel arch frame (3) to maintain F during the compression process. min The value remains unchanged; S7, deformation reaches the reserved deformation amount: the surrounding rock continues to deform until the socket sleeve (11) contacts the limit sleeve, that is, the ideal state of optimal support timing is reached, and at this time the self-servo steel arch frame (3) enters the rigid support stage; S8. Dismantling of the axial force control device (2): After the hydraulic device is depressurized, the hydraulic spring (10) is taken out and can be recycled at the next application point.

6. The construction method of a self-servo steel arch frame with pre-deformation control according to claim 5 is characterized in that: The forces acting on the support structure in S2 include the axial force of the steel arch frame (3), the primary support sprayed concrete, and the tensile stress of the anchor rods.

7. The construction method of a self-servo steel arch frame with pre-deformation control according to claim 5, characterized in that: The optimal support timing in S2 is when the surrounding rock undergoes certain deformation and exerts its maximum bearing capacity, and at the same time, the axial force of the steel arch frame (3) is minimal, the anchor tension is relatively small, the initial lining sprayed concrete compressive stress is less than the concrete compressive strength, and the surrounding rock plastic zone range is less than the anchor length.

8. The construction method of a self-servo steel arch frame with pre-deformation control according to claim 5, characterized in that: After the blasting excavation is completed at the application point in S5, it is necessary to immediately assemble the steel arch frame (3) and install the axial force control device (2).

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