Retractable supporting structure and method for rheological soft rock tunnel

Abstract

The invention provides an embeddable support structure for rheological soft rock tunnel and a method thereof, the embeddable support structure comprises a sleeve joint, foam metal channel steel and I-shaped steel, outer embedded teeth are arranged at the belly part of the connecting end of the I-shaped steel, the sleeve joint and the I-shaped steel are mutually matched for use, and inner embedded teeth are arranged in the sleeve joint. The inner embedded teeth and the outer embedded teeth are used in cooperation, the two pieces of I-shaped steel are connected under the action of the sleeve connector, and foam metal channel steel is further fixed to the backs of the pieces of I-shaped steel. In the rheological soft rock tunnel, the surrounding rock pressure can be continuously increased within a long period of time. During construction, the foam metal channel steel is subjected to yield compression, and one-time energy release is completed; along with the increase of the stress of the surrounding rock, the steel arch and the surrounding rock are greatly deformed by utilizing the contraction of the joint, the deformation energy of the surrounding rock is continuously released, the pressure of the surrounding rock acting on the primary support is reduced, and the release of secondary energy is realized.

Description

Technical Field

[0001] The invention belongs to the technical field of civil engineering, and in particular relates to an embeddable support structure for a rheological soft rock tunnel and a method thereof. Background Art

[0002] According to the statistical data of a large number of rheological soft rock tunnels at home and abroad, when a large deformation disaster occurs in a rheological soft rock tunnel, there are generally characteristics such as large deformation, high deformation rate, long deformation duration, and long-term non-convergence. Due to the energy release effect caused by tunnel excavation, if the deformation of the surrounding rock is controlled blindly, the surrounding rock can only reach a balanced state when a large support reaction force is provided.

[0003] According to the concept of "constraint-convergence method", if some measures can be taken to allow the surrounding rock to deform to a certain extent before the support structure is subjected to force, the force acting on the support will be reduced to a certain extent, which can save engineering costs to a large extent. In addition, the plastic rheological effect of the surrounding rock leads to a long-term increase in surrounding rock pressure. If the stiffness of the support structure is insufficient and the surrounding rock stress cannot reach a state of equilibrium, the tunnel deformation will continue to grow and be difficult to converge, leading to large deformation failure. How to determine the energy release of the surrounding rock is the key to controlling the large deformation problem of rheological soft rock tunnels, especially how to calculate the released displacement, which is a problem worthy of study. At present, the calculation of the deformation release of the support structure of rheological soft rock tunnels is mostly based on empirical values ​​and is not universal.

[0004] Based on this, a retractable support structure and method for rheological soft rock tunnels are proposed. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a retractable support structure and method for rheological soft rock tunnels in view of the deficiencies of the above-mentioned prior art, so as to solve the problems raised in the above-mentioned background technology.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0007] In a first aspect, a collapsible support structure for a rheological soft rock tunnel comprises a sleeve joint, a foam metal channel steel, and an I-shaped steel;

[0008] There are at least two I-shaped steels, and an external cog is provided on the abdomen of the connecting end of the I-shaped steel. The sleeve joint cooperates with the I-shaped steel, and an internal cog is provided in the sleeve joint. The internal cog and the external cog cooperate with each other to complete the connection of the two I-shaped steels under the action of the sleeve joint.

[0009] A foam metal channel steel is also fixed to the back of the I-shaped steel.

[0010] As a further description of the present invention, the inner embedded teeth are specifically an inverted sawtooth structure, and the inner embedded teeth cooperate with the outer embedded teeth to form a locking structure.

[0011] As a further illustration of the present invention, grouting holes are also provided on the foam metal channel steel.

[0012] As a further illustration of the present invention, the length of the foam metal channel steel is less than the length of the I-beam steel.

[0013] As a further illustration of the present invention, the inner cog is provided with 8-12 sections, and the outer cog 4 is provided with 4-6 sections.

[0014] In a second aspect, a method for using a collapsible support structure for a rheological soft rock tunnel comprises the following steps:

[0015] S1. First, weld a section of foam metal channel steel on the back of the I-beam, reserve a connection part at the joint of the I-beam, and then insert the connection parts of the adjacent I-beams into the sleeve joints to form a steel arch support structure. When starting to connect, make the outer teeth on the I-beam and the inner teeth inside the sleeve joint engage with each other;

[0016] S2. After using an external object to cover the external cogs of the unembedded part, the section is sprayed with concrete;

[0017] S3. Under the pressure of the surrounding rock, the foam metal channel steel on the back of the I-beam will yield and be compressed, achieving the release of primary energy;

[0018] When the pressure increases, the inner teeth on the inside of the sleeve joint and the outer teeth on the end of the I-beam are displaced, and the circumference of the steel arch support structure shrinks. As the stress increases, the outer teeth are completely embedded in the inner teeth to complete the buckling, and the contraction length is ΔL, realizing the release of secondary energy.

[0019] When the secondary energy is released, the connecting part of the I-beam is completely embedded in the sleeve joint to form a mutually interlocking locking structure. The steel arch support structure is transformed from an embedded structure to a rigid structure. The joints of adjacent I-beams are then welded and a layer of concrete is sprayed.

[0020] As a further explanation of the present invention, before spraying concrete in S3, if there is a gap in the foam metal channel steel, grouting is first injected into the foam metal channel steel through the grouting holes until the gap is completely filled before the concrete spraying operation is performed.

[0021] As a further illustration of the present invention, the contraction length ΔL is calculated as follows:

[0022] First, collect the surrounding rock deformation monitoring data of the engineering test section, and use the negative exponential function to fit the deformation history curve equation:

[0023] s(t)=AB·exp(-Ct)

[0024] In the formula, A, B, and C are fitting parameters, t is time, and s is radial deformation;

[0025] The shrinkage of the support structure is designed using the deformation value at the moment of deformation stability. The radial deformation of the surrounding rock at the moment of deformation stability is

[0026] s=A

[0027] Then ΔL is:

[0028]

[0029] Where N is the number of circumferential joints;

[0030] Since the compression of the foam metal channel steel 2 has achieved a primary energy release, the value of ΔL in the above formula is multiplied by 70%.

[0031] Compared with the prior art, the present invention has the following advantages:

[0032] 1. The present invention can flexibly adjust the release amount of surrounding rock deformation through a preset sleeve joint, thereby controlling the surrounding rock pressure acting on the support structure to a minimum value;

[0033] 2. In the present invention, the back of the I-shaped steel arch is welded with a foam metal channel steel. The foam metal material has a low density and relatively high strength. Under the action of a large surrounding rock pressure, the foam metal channel steel absorbs the energy released by the surrounding rock through its own compression deformation, thereby reducing the surrounding rock pressure acting on the initial support. At the same time, the channel steel has a certain compressive strength during the energy absorption deformation process, and the buffer time is long and there is no rebound.

[0034] 3. In rheological soft rock tunnels, the surrounding rock pressure will continue to increase for a long period of time. During construction, the foam metal channel steel yields and compresses, completing the release of primary energy; as the surrounding rock stress further increases, the sleeve joint of the steel arch continues to play a role, and the internal teeth of the sleeve joint and the external serrated teeth at the end of the I-beam form a lock-type structure, using the contraction of the joint to cause the steel arch and the surrounding rock to deform greatly, continue to release the deformation energy of the surrounding rock, reduce the surrounding rock pressure acting on the initial support, and achieve the release of secondary energy.

[0035] 4. The contraction length of the sleeve joint can be calculated and determined based on the deformation monitoring data of the on-site test section. It does not need to be determined based on experience, which is convenient and practical. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0037] Figure 2 It is a schematic diagram of the end structure of the I-beam of the present invention;

[0038] Figure 3 This is a schematic diagram of the foam metal channel steel of the present invention before compression;

[0039] Figure 4 This is a schematic diagram of the foam metal channel steel after compression of the present invention;

[0040] Figure 5 This is a schematic diagram of the initial connection state of the I-shaped steel of the present invention;

[0041] Figure 6 It is a schematic diagram of the connection state after adjacent I-shaped steels of the present invention are completely embedded in the sleeve joint;

[0042] Figure 7 It is a structural schematic diagram of the steel arch support structure in the present invention before concrete is sprayed;

[0043] Figure 8 It is a schematic diagram of the structure of the steel arch support structure after spraying concrete in the present invention.

[0044] Description of reference numerals:

[0045] 1-sleeve joint; 2-foam metal channel steel; 3-I-beam; 4-external teeth; 5-internal teeth; 6-grouting hole; 7-concrete. DETAILED DESCRIPTION

[0046] 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 ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] like Figure 1-8 As shown, the present invention provides a technical solution: a retractable support structure for rheological soft rock tunnels, comprising a sleeve joint 1, a foam metal channel steel 2, and an I-shaped steel 3;

[0048] Among them, at least two I-shaped steels 3 are provided, and an external cog 4 is provided on the abdomen of the connecting end of the I-shaped steel 3, the sleeve joint 1 and the I-shaped steel 3 are used in cooperation with each other, and an internal cog 5 is provided in the sleeve joint 1, and the internal cog 5 and the external cog 4 are used in cooperation with each other, specifically, the internal cog 5 is provided with 8-12 sections, and the external cog 4 is provided with 4-6 sections, and the internal cog 5 is specifically an inverted sawtooth structure, and the internal cog 5 and the external cog 4 cooperate with each other to form a locking structure, and the connection of the two I-shaped steels 3 is completed under the action of the sleeve joint 1;

[0049] The back of the I-shaped steel 3 is also fixed with a foam metal channel steel 2. The foam metal material has a low density and relatively high strength. Under the action of a large surrounding rock pressure, the foam metal channel steel 2 absorbs the energy released by the surrounding rock through its own compression deformation, thereby reducing the surrounding rock pressure acting on the initial support. At the same time, the foam metal channel steel 2 has a certain compressive strength during the energy absorption deformation process, has a long buffer time and does not rebound, and a grouting hole 6 is also provided on the foam metal channel steel 2.

[0050] The length of the foam metal channel steel 2 is smaller than that of the I-shaped steel 3 .

[0051] The method for using the above-mentioned collapsible support structure for rheological soft rock tunnels comprises the following steps:

[0052] S1. First, weld a section of foam metal channel steel 2 on the back of the I-shaped steel 3, reserve a connection part at the joint of the I-shaped steel 3, and then respectively insert the connection parts of the adjacent I-shaped steels 3 into the sleeve joint 1 to form a steel arch support structure. When starting to connect, the outer cog 4 on the I-shaped steel 3 and the inner cog 5 inside the sleeve joint 1 are engaged with each other at two sections;

[0053] S2, after using wooden boards to cover the unembedded portion of the outer cog 4, the cross section is sprayed with concrete 7;

[0054] S3. Under the pressure of the surrounding rock, the foam metal channel steel 2 on the back of the I-shaped steel 3 will yield and be compressed, thus achieving a primary energy release;

[0055] When the pressure increases, the inner cog 5 on the inner side of the sleeve joint 1 and the outer cog 4 at the end of the I-shaped steel 3 are displaced, and the circumference of the steel arch support structure shrinks. As the stress increases, the outer cog 4 is completely embedded in the inner cog 5 to complete the buckling, and the contraction length is ΔL, realizing the release of secondary energy;

[0056] The contraction length ΔL is calculated as follows:

[0057] The surrounding rock deformation history curve equation obtained by fitting the surrounding rock deformation monitoring data of the engineering test section is:

[0058] s(t)=AB·exp(-Ct)

[0059] In the formula, A, B, and C are fitting parameters, specifically A is 80, B is 65, and C is 0.3. t is the time in days, and s is the radial deformation in centimeters. That is,

[0060] s=80-65·exp(-0.3t)

[0061] Each ring lining is provided with 5 joints in the annular direction, and the shrinkage length ΔL of each shrinkage joint is designed as:

[0062]

[0063] That is, one sleeve joint 1 is respectively arranged at the left and right connection of the upper middle step, the left and right connection of the middle and lower step, and the middle of the inverted arch, and the contraction length of each sleeve joint 1 is 70 cm.

[0064] When the secondary energy is released, the connection part of the I-beam 3 is completely embedded in the sleeve joint 1 to form a mutually interlocking locking structure. The steel arch support structure is transformed from an embedded structure to a rigid structure. The joint parts of the adjacent I-beams 3 are then welded and a layer of concrete 7 is sprayed.

[0065] Before spraying concrete 7 , if there is a gap in the foam metal channel steel 2 , grouting is first injected into the foam metal channel steel 2 through the grouting holes 6 until the gap is completely filled before spraying concrete 7 .

[0066] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0067] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A retractable support structure for rheological soft rock tunnels, characterized by: It comprises a sleeve joint (1), a foam metal channel steel (2), and an I-shaped steel (3); At least two I-shaped steels (3) are provided, and an external cog (4) is provided on the abdomen of the connecting end of the I-shaped steel (3); the sleeve joint (1) and the I-shaped steel (3) are used in cooperation with each other, and an internal cog (5) is provided in the sleeve joint (1); the internal cog (5) and the external cog (4) are used in cooperation with each other, and the connection of the two I-shaped steels (3) is completed under the action of the sleeve joint (1); A foam metal channel steel (2) is also fixed to the back of the I-shaped steel (3).

2. The collapsible support structure for rheological soft rock tunnel according to claim 1, characterized in that: The inner embedded teeth (5) are specifically an inverted sawtooth structure, and the inner embedded teeth (5) and the outer embedded teeth (4) cooperate with each other to form a locking structure.

3. The collapsible support structure for rheological soft rock tunnel according to claim 1, characterized in that: The foam metal channel steel (2) is also provided with grouting holes (6).

4. The collapsible support structure for rheological soft rock tunnel according to claim 1, characterized in that: The length of the foam metal channel steel (2) is shorter than the length of the I-shaped steel (3).

5. The collapsible support structure for rheological soft rock tunnel according to claim 1, characterized in that: The inner cog (5) is provided with 8 to 12 sections, and the outer cog (4) is provided with 4 to 6 sections.

6. A method for using a collapsible support structure for a rheological soft rock tunnel according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1. First, a section of foam metal channel steel (2) is welded on the back of the I-shaped steel (3), and a connection part is reserved at the joint of the I-shaped steel (3). Then, the connection parts of the adjacent I-shaped steels (3) are respectively inserted into the sleeve joint (1) to form a steel arch support structure. When the connection is started, the outer cogs (4) on the I-shaped steel (3) and the inner cogs (5) inside the sleeve joint (1) are engaged with each other at two sections. S2, after using an external object to cover the unembedded portion of the external cog (4), the cross section is sprayed with concrete (7); S3. Under the pressure of the surrounding rock, the foam metal channel steel (2) at the back of the I-shaped steel (3) will yield and be compressed, thus achieving a primary energy release; When the pressure increases, the inner cog (5) on the inner side of the sleeve joint (1) and the outer cog (4) on the end of the I-shaped steel (3) are displaced, and the circumference of the steel arch support structure shrinks. As the stress increases, the outer cog (4) is completely embedded in the inner cog (5) to complete the buckling, and the contraction length is ΔL, thereby achieving the release of secondary energy. When the secondary energy is released, the connection part of the I-shaped steel (3) is completely embedded in the sleeve joint (1) to form a mutually interlocking lock-type structure, and the steel arch support structure is transformed from an embedded structure to a rigid structure. The joint parts of the adjacent I-shaped steels (3) are then welded and a layer of concrete (7) is sprayed.

7. The method for using the collapsible support structure for rheological soft rock tunnel according to claim 6, characterized in that: In S3, before spraying concrete (7), if there is a gap in the foam metal channel steel (2), grouting is first injected into the foam metal channel steel (2) through the grouting hole (6) until the gap is completely filled, and then the concrete (7) is sprayed.

8. The method for using the collapsible support structure for rheological soft rock tunnel according to claim 6, characterized in that: The contraction length ΔL is calculated as follows: First, collect the surrounding rock deformation monitoring data of the engineering test section, and use the negative exponential function to fit the deformation history curve equation: s(t)=AB·exp(-Ct) In the formula, A, B, and C are fitting parameters, t is time, and s is radial deformation; The shrinkage of the support structure is designed using the deformation value at the moment of deformation stability. The radial deformation of the surrounding rock when the deformation is stable is: s=A Then ΔL is: Where N is the number of circumferential joints; Since the compression of the foam metal channel steel (2) has achieved a primary energy release, the value of ΔL in the above formula is multiplied by 70%.

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