Timing large-deformation tunnel buffer layer support parameter toughness design method

Abstract

The invention discloses an aging large-deformation tunnel buffer layer support parameter toughness design method, and relates to the field of energy tunnel design, and the method comprises the following steps: S1, according to a toughness design theory, respectively drawing performance evolution curves of a support structure when surrounding rock aging deformation is considered and not considered; s2, on the basis of the concept of toughness, assuming that the surrounding rock age deformation is external disturbance capable of influencing the performance of the supporting structure, and calculating the toughness of the supporting structure after different buffer layers are adopted; s3, buffer layer supporting parameters are determined according to the toughness value of the supporting structure after different buffer layers are adopted; the toughness theory is applied to the supporting design of the buffer layer, the rationality of a supporting system can be improved, and the method has important significance on the safety of the high-crustal-stress soft rock tunnel in the operation period.

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 a time-dependent large deformation. Background Art

[0002] With the large demand and construction of deep and long tunnels, when deep and long tunnels pass through soft rock formations, large deformation disasters are prone to occur under the combined effects of high ground stress, groundwater and aging characteristics of surrounding rock. Large deformation of soft rock tunnels will not only cause deformation and damage of support structures during construction, but also cause structural damage to tunnels during operation, seriously affecting the operational safety of tunnels. Buffer layer yield support is one of the commonly used methods to deal with long-term aging deformation of surrounding rock. However, how to determine the buffer layer support parameters is a technical problem that needs to be solved urgently. Summary of the invention

[0003] In order to solve the above problems, the present application provides a method for designing the toughness of the buffer layer support parameters of a tunnel with a 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 toughness parameters of buffer layer support for 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 using different buffer layers is calculated.

[0007] S3 determines the buffer layer support parameters according to the toughness value of the support structure after using 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 of the performance Q of the support structure changing with time t.

[0009] For example, in the toughness design method for supporting parameters of a tunnel buffer layer with large aging deformation provided in an embodiment, in S1, when drawing the performance evolution curve of the tunnel support structure without considering the aging deformation of the surrounding rock, the decrease in the performance evolution curve of the support structure is mainly caused by the performance degradation of the support material, and 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 aging 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 aging large-deformation tunnel buffer layer provided in an embodiment, in S2, the performance curves of the support structure under different buffer layer support parameters are plotted, 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 buffer layer support parameters.

[0014] For example, in the ductility design method of the support parameters of the aging large-deformation tunnel buffer layer provided in an embodiment, in S2, assuming that the surrounding rock aging deformation 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 surrounding rock aging deformation 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 aging 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 aging large-deformation tunnel buffer layer provided in an embodiment, in S3, the method for determining the buffer layer support parameters 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 buffer layer support parameters.

[0019] For example, in the ductility design method of the support parameters of the aging large-deformation tunnel buffer layer provided in an embodiment, in S2, when plotting the performance curves of the support structure under different buffer layer support parameters, the performance curves of the support structure under different buffer layer support parameters are determined by the engineering category or numerical simulation method.

[0020] The beneficial effects brought about by a method for designing the toughness of buffer layer support parameters of a tunnel with a time-dependent large deformation provided in some embodiments of the present application are as follows: the present application applies the 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 drawings required for use in the embodiments will be briefly introduced below. 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 creative work.

[0022] Figure 1 This is a flow chart of the toughness design method for the buffer layer support parameters of the time-dependent large deformation tunnel in 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 the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0025] Unless otherwise defined, the technical terms or scientific terms used in the present disclosure should be understood by people with ordinary skills in the field to which the present disclosure belongs. The "first", "second" and similar words used in the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but can 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 described object changes, the relative positional relationship may also change accordingly.

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

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

[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 changing with time t.

[0029] According to the ductility design theory, draw the performance evolution curve QN of the tunnel support structure without considering the influence of the time-dependent deformation of the soft surrounding rock 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 performance deterioration 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 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, under the action of the time-dependent deformation of the surrounding rock, the attenuation rate of the performance Q of the support system will increase significantly, as Figure 2 the curve shown in. At this time, the support system fails at t a , that is, damage occurs, and the design parameters of the support structure cannot meet the design requirements.

[0035] S2 Based on the concept of ductility, assume that the time-dependent deformation of the surrounding rock is an external disturbance that can affect the performance of the support structure. Draw the performance curves of the support structure under different support parameters of the buffer layer through engineering classification or numerical simulation methods, and calculate the ductility of the support structure after adopting different buffer layers 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 absorb the time-dependent deformation of the surrounding rock well 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 cases:

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

[0038] Case II: If Figure 2 Performance curve of the medium 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 medium 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 using 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 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 of the present application applies the 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.

[0049] Although the implementation scheme of the present application has been disclosed as above, it is not limited to the applications listed in the specification and implementation modes, and it can be fully applicable to various fields suitable for the present application. For those familiar with the art, 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 the illustrations shown and described herein.

Claims

1. A method for designing the toughness of buffer layer support parameters of tunnels with time-dependent large deformation, characterized in that: It includes the following steps: S1 According to the ductility design theory, respectively draw the performance evolution curves of the support structure when considering and not considering the time-dependent deformation of the surrounding rock; S2 Based on the concept of ductility, assume that the time-dependent deformation of the surrounding rock is an external disturbance that can affect the performance of the support structure, and calculate the ductility of the support structure after using different buffer layers; S3 Determine the buffer layer support parameters according to the ductility values of the support structure after using different buffer layers.

2. According to the method for designing toughness of buffer layer support parameters of tunnel with large deformation under time aging, it is characterized by: The performance evolution curve of the support structure is the curve of the performance Q of the support structure changing with time t.

3. According to the method for designing toughness of buffer layer support parameters of tunnel with large deformation under time aging, it is characterized by: In S1, when drawing the performance evolution curve of the tunnel support structure without considering the time-dependent deformation of the surrounding rock, the decline of the performance evolution curve of the support structure is mainly caused by the performance deterioration of the support material. The performance calculation method of the support structure is: Among them, γ max is the design bearing capacity of the supporting structure or the strength of the supporting structure material, and γ(t) is the force on the supporting structure at time t.

4. According to the method for designing toughness of buffer layer support parameters of tunnels with large deformation under time-dependent conditions, the method is characterized in that: When 0 < Q(t) ≤ 1, the support structure is within the allowable bearing capacity range. When Q(t) < 0, the support structure fails.

5. According to the method for designing toughness of buffer layer support parameters of tunnel with large time-dependent deformation according to claim 4, it is characterized in that: 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 using different buffer layers according to the performance curves of the support structure under different buffer layer support parameters.

6. The method for designing toughness of buffer layer support parameters for tunnels with large time-dependent deformation according to claim 5 is characterized in that: In S2, assume 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 using the buffer layer 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 It is the area enclosed by the performance evolution curve of the support structure after adopting the buffer layer and the coordinate axis.

7. The method for designing toughness of buffer layer support parameters for tunnels with large time-dependent deformation according to claim 6 is characterized in that: When a certain buffer layer is used, the performance curve of the support structure is x When Q(t)=0, and t x <t n , then the buffer layer support parameters cannot meet the design requirements.

8. The method for designing toughness of buffer layer support parameters for tunnels with large time-dependent deformation according to claim 7 is characterized in that: In S3, the method for determining the buffer layer support parameters according to the ductility values of the support structure after using different buffer layers is: compare the ductility values of the support structure after using different buffer layers, select the maximum ductility value Re, and determine the buffer layer support parameters.

9. The method for designing toughness of buffer layer support parameters for tunnels with large time-dependent deformation according to claim 5 is characterized in that: 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.

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