A toughness design method for buffer layer support parameters of tunnels with large time-dependent deformation

Abstract

The present application discloses a method for designing the toughness of support parameters of a buffer layer in a tunnel with large time-dependent deformation, which relates to the field of energy tunnel design and comprises the following steps: S1, based on the toughness design theory, respectively drawing the performance evolution curves of the support structure with and without considering the time-dependent deformation of the surrounding rock; S2, based on the concept of toughness, assuming that the time-dependent deformation of the surrounding rock is an external disturbance that can affect the performance of the support structure, and calculating the toughness of the support structure after adopting different buffer layers; S3, determining the buffer layer support parameters according to the toughness values ​​of the support structure after adopting different buffer layers; The present application applies the toughness theory to the buffer layer support design, which can improve the rationality of the support system and is of great significance to the safety of high ground stress soft rock tunnels during operation.

Description

Technical Field

[0001] The present application relates to the technical field of tunnel construction, and in particular to a method for designing toughness parameters of a buffer layer support for a tunnel with large time-dependent deformation. Background Art

[0002] With the increasing demand and construction of deep, long tunnels, tunnels passing through soft rock formations are prone to large deformation hazards caused by the combined effects of high ground stress, groundwater, and the aging characteristics of the surrounding rock. Large deformation in soft rock tunnels can lead to deformation and damage to support structures during construction and structural damage during operation, seriously impacting tunnel safety. Buffer layer yield support is a commonly used method to address long-term aging deformation of the surrounding rock. However, determining the buffer layer support parameters is a technical challenge that urgently needs to be addressed. Summary of the Invention

[0003] To address the above-mentioned issues, this application provides a method for designing the toughness of support parameters for the buffer layer of a tunnel with time-dependent large deformation, which can improve the rationality of the support system and is of great significance to the safety of high-stress soft rock tunnels during operation. The technical solution is as follows:

[0004] The present application provides a method for designing the toughness of buffer layer support parameters in tunnels with time-dependent large deformation, comprising the following steps:

[0005] S1 Based on the toughness design theory, the performance evolution curves of the support structure are drawn with and without considering the time-dependent deformation of the surrounding rock;

[0006] S2 is based on the concept of toughness. It assumes that the time-dependent deformation of the surrounding rock is an external disturbance that can affect the performance of the support structure. The toughness of the support structure after adopting different buffer layers is calculated.

[0007] S3 determines the buffer layer support parameters according to the toughness value of the support structure after adopting different buffer layers.

[0008] For example, in the time-dependent large deformation tunnel buffer layer support parameter toughness design method provided in one embodiment, the performance evolution curve of the support structure is a curve showing the change of the performance Q of the support structure with time t.

[0009] For example, in the method for designing the toughness of support parameters of a tunnel buffer layer with large time-dependent deformation provided in one embodiment, in S1, when plotting the performance evolution curve of the tunnel support structure without considering the time-dependent deformation of the surrounding rock, the decline in the performance evolution curve of the support structure is mainly due to the performance degradation of the support material. The performance calculation method of the support structure is:

[0010]

[0011] Among them, γ maxγ₀ is the design bearing capacity of the support structure or the strength of the support structure material, and γ(t) is the force on the support structure at time t.

[0012] For example, in the ductility design method of the support parameters of the time-dependent large deformation tunnel buffer layer provided in an embodiment, when 0 < Q(t) ≤ 1, the support structure is within the allowable bearing capacity range, and when Q(t) < 0, the support structure fails.

[0013] For example, in the ductility design method of the support parameters of the time-dependent large deformation tunnel buffer layer provided in an embodiment, in S2, draw the performance curves of the support structure under different buffer layer support parameters, and calculate the ductility of the support structure after adopting different buffer layers according to the performance curves of the support structure under different buffer layer support parameters.

[0014] For example, in the ductility design method of the support parameters of the time-dependent large deformation tunnel buffer layer provided in an embodiment, in S2, assuming that the time-dependent deformation of the surrounding rock is an external disturbance that can affect the performance of the support structure, the calculation method of the ductility Re of the support structure after adopting the buffer layer is:

[0015]

[0016] where S0 is the area enclosed by the performance evolution curve of the tunnel support structure without considering the time-dependent deformation of the surrounding rock and the coordinate axes at the design service life t of the tunnel n of the tunnel, and S x is the area enclosed by the performance evolution curve of the support structure after adopting the buffer layer and the coordinate axes.

[0017] For example, in the ductility design method of the support parameters of the time-dependent large deformation tunnel buffer layer provided in an embodiment, when a certain buffer layer is adopted, at time t x of the performance curve of the support structure, Q(t) = 0, and at time t x < t n , then the support parameter of this buffer layer does not meet the design requirements.

[0018] For example, in the ductility design method of the support parameters of the time-dependent large deformation tunnel buffer layer provided in an embodiment, in S3, the method for determining the support parameters of the buffer layer according to the ductility values of the support structures after adopting different buffer layers is: compare the ductility values of the support structures after adopting different buffer layers, select the maximum ductility value Re, and determine the support parameters of the buffer layer.

[0019] For example, in the ductility design method of the support parameters of the time-dependent large deformation tunnel buffer layer provided in an embodiment, in S2, when drawing the performance curves of the support structure under different buffer layer support parameters, determine the performance curves of the support structure under different buffer layer support parameters through engineering categories or numerical simulation methods.

[0020] The beneficial effects of a time-dependent large deformation tunnel buffer layer support parameter toughness design method provided in some embodiments of the present application are as follows: the present application applies toughness theory to the buffer layer support design, which can improve the robustness and rationality of the support system, and is of great significance to the safety of high-ground stress soft rock tunnels during operation, and has important significance and promotion prospects in engineering construction. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of this specification or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 This is a flow chart of the toughness design method for buffer layer support parameters of a tunnel with large time-dependent deformation according to this application;

[0023] Figure 2 Performance evolution curve of the support structure under different conditions. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0025] Unless otherwise defined, the technical or scientific terms used in this disclosure should have the usual meanings understood by persons of ordinary skill in the field to which this disclosure belongs. The words "first", "second" and similar terms used in this disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. Words such as "include" or "comprise" mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connect" or "connected" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0026] This application provides a method for designing the toughness of buffer layer support parameters in tunnels with large deformation over time. Figure 1 As shown, the following steps are included:

[0027] S1 According to the ductility design theory, the performance evolution curves of the support structure are respectively plotted when considering and not considering the time-dependent deformation of the surrounding rock mass.

[0028] Among them, as Figure 2 shown, the performance evolution curve of the support structure is the curve of the performance Q of the support structure varying with time t.

[0029] According to the ductility design theory, the performance evolution curve QN of the tunnel support structure without considering the influence of the time-dependent deformation of the soft surrounding rock mass is plotted as Figure 2 shown. The support structure does not show damage during the designed service life t n of the tunnel. At this time, the decline of the performance evolution curve of the support structure is mainly caused by the deterioration of the performance of the support material. The performance Q of the support structure is defined as:

[0030]

[0031] Among them, γ max is the bearing capacity of the support structure or material, which can be the compressive strength or tensile strength of the support material, or the allowable deformation amount and allowable bearing capacity of the support structure. γ(t) is the force of the support structure at time t.

[0032] When 0 < Q(t) ≤ 1, the support structure is within the allowable bearing capacity range;

[0033] When Q(t) < 0, the support structure will be damaged.

[0034] When considering the time-dependent characteristics of the soft surrounding rock mass, under the action of the time-dependent deformation of the surrounding rock mass, the attenuation rate of the performance Q of the support system will increase significantly, as Figure 2 shown by the curve in. At this time, the support system is damaged at time t a , and the design parameters of the support structure cannot meet the design requirements.

[0035] S2 Based on the concept of ductility, assuming that the time-dependent deformation of the surrounding rock mass is an external disturbance that can affect the performance of the support structure, the performance curves of the support structure under different support parameters of the buffer layer are plotted by methods such as engineering classification or numerical simulation, and the ductility of the support structure after adopting different buffer layers is calculated according to the performance curves of the support structure under different support parameters of the buffer layer;

[0036] When the buffer layer support scheme is adopted, since the buffer layer can well absorb the time-dependent deformation of the surrounding rock mass and reduce the force on the support structure, therefore, as Figure 2 shown, the performance curve of the support structure gradually moves to the right side of the coordinate axis. After adopting the buffer layer, the performance curve of the support structure can be divided into the following three situations:

[0037] Situation I: As Figure 2 Performance curve of the middle support structure As shown, its intersection with the horizontal axis t is t b <t n ;

[0038] Case II: If Figure 2 Performance curve of the middle support structure As shown, when t≤tn, it does not intersect with the horizontal axis t;

[0039] Case III: If Figure 2 The performance curve of the middle support structure is given by and When t≤tn, it does not intersect with the horizontal axis t.

[0040] Performance evolution curve of tunnel support structure without considering the time-dependent deformation of surrounding rock The area enclosed by the coordinate axes is S QNCO The time-dependent deformation of the surrounding rock is regarded as the external disturbance that can affect the performance of the support structure. The toughness Re of the support structure after using different buffer layers is defined as the area enclosed by the performance curve of the support structure and the coordinate axis and S QNCO The toughness Re of the support structure in the above three cases are:

[0041] Situation I:

[0042] Case II:

[0043] Case III:

[0044] S3 determines the buffer layer support parameters according to the toughness value of the support structure after adopting different buffer layers.

[0045] From the definition of toughness, it can be seen that in an ideal situation, the buffer layer completely eliminates the influence of the aging deformation of the surrounding rock, and the toughness Re = 1.0;

[0046] In case I, the performance curve of the support structure is In t b When Q(t)=0, and t b <t n , then the buffer layer support parameters cannot meet the design requirements;

[0047] In Case II and Case III, the buffer layer support parameters with a higher Re value, i.e., Case III, are selected as the final buffer layer support parameters.

[0048] The time-dependent large deformation tunnel buffer layer support parameter toughness design method proposed in this application applies the toughness theory to the buffer layer support design, which can improve the robustness and rationality of the support system. It is of great significance to the safety of high-ground stress soft rock tunnels during operation, and has important significance and promotion prospects in engineering construction.

[0049] Although the implementation scheme of the present application has been disclosed as above, it is not limited to the applications listed in the description and implementation mode. It can be fully applied to various fields suitable for the present application. For those familiar with this field, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present application is not limited to the specific details and illustrations shown and described herein.

Claims

1. A method for designing toughness parameters of buffer layer support for tunnels with large time-dependent deformation, characterized in that: The following steps are involved: S1 Based on the toughness design theory, the performance evolution curves of the support structure are plotted with and without considering the time-dependent deformation of the surrounding rock. When the performance evolution curve of the tunnel support structure is plotted without considering the time-dependent deformation of the surrounding rock, the decline in the performance evolution curve of the support structure is mainly due to the performance degradation of the support material. The performance calculation method of the support structure is: ； in, Design the bearing capacity of the supporting structure or the strength of the supporting structure material, is the force on the supporting structure at time t; When the supporting structure is within the allowable bearing capacity range, When the supporting structure is damaged; S2 is based on the concept of toughness. It is assumed that the time-dependent deformation of the surrounding rock is an external disturbance that can affect the performance of the support structure. The toughness of the support structure after adopting different buffer layers is calculated. In said S2, the performance curve of the support structure under different buffer layer support parameters is drawn, and the toughness of the support structure after adopting different buffer layers is calculated based on the performance curve of the support structure under different buffer layer support parameters. In said S2, it is assumed that the time-dependent deformation of the surrounding rock is an external disturbance that can affect the performance of the support structure. The toughness of the support structure after adopting the buffer layer is calculated. The calculation method is: ； Where S0 is the design service life of the tunnel n When the performance evolution curve of the tunnel support structure without considering the time-dependent deformation of the surrounding rock is taken into account, the area enclosed by the coordinate axis is S x is the area enclosed by the performance evolution curve of the support structure after adopting the buffer layer and the coordinate axis; S3 determines the buffer layer support parameters according to the toughness value of the support structure after adopting different buffer layers.

2. The method for designing toughness of buffer layer support parameters for tunnels with large time-dependent deformation according to claim 1 is characterized in that: The performance evolution curve of the support structure is a curve showing the change of the performance Q of the support structure with time t.

3. The method for designing toughness of buffer layer support parameters for tunnels with large time-dependent deformation according to claim 1 is characterized in that: When a certain buffer layer is adopted, the performance curve of the support structure is x hour, , and t x t n , then the buffer layer support parameters cannot meet the design requirements.

4. The method for designing toughness of buffer layer support parameters for tunnels with large time-dependent deformation according to claim 3 is characterized in that: In said S3, the method for determining the buffer layer support parameters according to the toughness values ​​of the support structures after adopting different buffer layers is as follows: comparing the toughness values ​​of the support structures after adopting different buffer layers, and selecting the one with the largest toughness value. , determine the buffer layer support parameters.

5. The method for designing toughness of buffer layer support parameters for tunnels with large time-dependent deformation according to claim 1 is characterized in that: In said S2, when drawing the performance curve of the support structure under different buffer layer support parameters, the performance curve of the support structure under different buffer layer support parameters is determined by engineering classification or numerical simulation method.

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