Railway tunnel high-performance active support system design method considering space-time effect

Abstract

The invention relates to the technical field of civil engineering, and particularly discloses a railway tunnel high-performance active support system design method considering a space-time effect, which comprises the following steps: S1, establishing a tunnel early-strength and high-strength sprayed concrete layer calculation model; s2, determining calculation parameters required by the sprayed layer calculation model according to the tunnel early-high-strength sprayed concrete layer calculation model; s3, influence factors of surrounding rock deformation pressure borne by the tunnel early-strength and high-strength sprayed concrete layer are determined; s4, establishing a surrounding rock deformation pressure calculation method of the tunnel early-strength and high-strength sprayed concrete layer considering the surrounding rock level; and S5, establishing a surrounding rock deformation pressure calculation method of the tunnel early-strength and high-strength sprayed concrete layer considering the rock mass quality index. By adopting the railway tunnel high-performance active support system design method considering the space-time effect, the safety of the tunnel early-strength and high-strength sprayed concrete layer under different time, geological conditions, construction levels and support design parameters can be simply, quickly and accurately calculated.

Description

Technical Field

[0001] The invention relates to the technical field of civil engineering, and in particular to a design method for a high-performance active support system for a railway tunnel taking time and space effects into consideration. Background Art

[0002] The active support of the shotcrete layer is in close contact with the surrounding rock and is subject to the surrounding rock pressure generated by the surrounding rock, of which the most important are deformation pressure and loosening pressure. At present, the design of the support structure of deep buried railway tunnels in my country mainly adopts the surrounding rock pressure calculation method of deep buried tunnels in the specification. This method combines the advantages of sample statistics and surrounding rock classification empirical formulas, has clear physical concepts, and is convenient for engineering and technical personnel. It is an empirical formula for loosening pressure established based on landslide statistics. However, in recent years, with the increasing level of tunnel construction in my country, the number of long and large tunnels has increased, and landslide accidents have become less and less. At present, many tunnels in my country have gradually transitioned from the era of small manual machinery to the era of standard mechanized construction, and the construction level has been greatly improved. For example, the quality of advance support and anchor support has been improved, and the backfill grouting has been dense, which has greatly improved the self-bearing capacity of the surrounding rock, making the pressure on the shotcrete support structure the deformation pressure. Therefore, the use of the loosening pressure calculation method in the specification to design the existing tunnel shotcrete support structure in my country will inevitably lead to large safety reserves and waste of resources. Therefore, combined with the current construction technology of tunnels in my country, in order to achieve the safety and economy of tunnel construction in my country, it is necessary to develop deformation pressure calculation methods to guide the design of active support for railway tunnel spraying. At the same time, in actual engineering, the surrounding rock pressure has temporal and spatial variation characteristics. In addition, after the spraying structure is constructed, due to the influence of the age of the sprayed concrete, its mechanical properties and the resulting support effect also have a certain timeliness. It can be seen that if the temporal and spatial effects of the surrounding rock pressure and the sprayed concrete are not considered, the safety evaluation results of the active support structure of the sprayed layer of the railway tunnel during the construction period will be distorted.

[0003] At present, the safe design of early high-strength shotcrete layers has brought great challenges to engineering safety. Domestic and foreign scholars have provided some research basis through analogy design, model verification and field testing. However, the design method of high-performance active support shotcrete layers considering time and space effects is still not perfect. Therefore, it is of great significance to construct a high-performance active support design method considering time and space effects and realize the shotcrete support design based on time and space effects. Summary of the invention

[0004] The purpose of the present invention is to provide a design method for a high-performance active support system for a railway tunnel taking into account the time and space effects, to achieve a simple, fast and accurate calculation of the safety of the early high-strength shotcrete layer of the tunnel under different shotcrete support parameters, to provide a reference for the design of tunnel projects using shotcrete support, and to solve the problem of distortion of the safety evaluation results of the active support structure of the shotcrete layer of the railway tunnel during the construction period due to the time and space effects.

[0005] To achieve the above object, the present invention provides a design method for a high-performance active support system for a railway tunnel taking into account time and space effects, comprising the following steps: S1. Establish a calculation model for early high-strength shotcrete layer in tunnels; S2. Determine the calculation parameters required for the shotcrete calculation model based on the early high-strength shotcrete calculation model of the tunnel; S3. Determine the factors affecting the surrounding rock deformation pressure on the early high-strength shotcrete layer of the tunnel; S4. Establish a method for calculating the surrounding rock deformation pressure of the early high-strength shotcrete layer of the tunnel taking into account the surrounding rock level; S5. Establish a calculation method for surrounding rock deformation pressure of early high-strength shotcrete layer in tunnels taking into account rock mass quality indicators; S6. Establish a calculation method for the surrounding rock deformation pressure of a tunnel in a high-strength shotcrete layer taking into account the construction level; S7. Establish a calculation method for the surrounding rock deformation pressure of the early high-strength shotcrete layer of the tunnel considering the time and space effects; S8. Propose a safety evaluation method for early high-strength shotcrete layer in tunnels; S9. Determine the safety of shotcrete based on the calculation results of the early high-strength shotcrete layer calculation model of the tunnel; S10. Determine the design parameters of shotcrete based on the calculation results of the early high-strength shotcrete layer of the tunnel.

[0006] Preferably, in S1, the early high-strength shotcrete structure in the calculation model of the early high-strength shotcrete layer of the tunnel is simulated by beam units, the interaction between the early high-strength shotcrete and the stratum is simulated by radial tension-free springs and tangential springs, and the bottom of the model is fixed by fixed end constraints.

[0007] Preferably, in S2, the specific steps of determining the calculation parameters required for the shotcrete layer calculation model according to the tunnel early high-strength shotcrete layer calculation model include: S21. According to the hardening characteristics of shotcrete and the timeliness of its mechanical properties, the calculation method of strength parameters and deformation parameters of the early high-strength shotcrete layer of the tunnel considering the time and space effects is determined. The formula is as follows: ; ; in, is the calculation function of the change of the strength of the early high-strength shotcrete layer of the tunnel with time; For time, s ; For the early high-strength shotcrete layer of the tunnel Moment intensity, Pa; is the strength of the early high-strength shotcrete layer of the tunnel at the initial moment, Pa; is the calculation function of the elastic modulus of the early high-strength shotcrete layer of the tunnel changing with time; For the early high-strength shotcrete layer of the tunnel Elastic modulus at the moment, Pa; For the early high-strength shotcrete layer of the tunnel t Elastic modulus at the moment, Pa; is the elastic modulus of the early high-strength shotcrete layer of the tunnel at the initial moment, Pa; S22. Determine the spring reaction coefficient of the early high-strength shotcrete layer of the tunnel according to the railway tunnel design specifications or indoor experiments. In the absence of tests, the radial spring stiffness parameters between the shotcrete and the surrounding rock shall be selected according to the elastic reaction coefficient specified in the railway tunnel design specifications; the tangential spring stiffness coefficient shall be 1 / 2 of the radial spring stiffness coefficient.

[0008] Preferably, in S3, the specific steps of determining the factors affecting the surrounding rock deformation pressure on the early high-strength shotcrete layer of the tunnel include: S31. Through field measurements and literature research methods, a deformation pressure sample database considering different regions, time periods, and construction methods is formed, and the database is classified according to different surrounding rock levels, tunnel spans, and construction methods to analyze the characteristics and influencing factors of deformation pressure; S32. Determine the influencing factors of deformation pressure according to the deformation pressure sample database analysis; the influencing factors include surrounding rock grade, tunnel span, construction level, rock mass quality index and time-space effect.

[0009] Preferably, in S4, the specific steps of establishing a method for calculating the surrounding rock deformation pressure of the early high-strength shotcrete layer of the tunnel taking into account the surrounding rock level include: S41, decomposing the data of the deformation pressure sample database into vertical and horizontal uniformly distributed loads according to the area equivalence principle for calculation, and distributing them according to the uniformly distributed equivalent load mode; S42. Through multi-factor analysis method, taking into account the influencing factors of tunnel surrounding rock grade and tunnel span, the vertical deformation pressure calculation formula of surrounding rock is established by fitting and deduction, and the deformation pressure calculation formula with the highest correlation coefficient is selected as the final calculation formula of vertical deformation pressure. The formula is as follows: ; ; ; in, is the calculation function of the vertical deformation pressure of the surrounding rock considering the surrounding rock level; is the vertical deformation pressure value of surrounding rock considering the surrounding rock level, Pa; is the weight of the surrounding rock, kN / m 3 ; is the equivalent deformation pressure height value, m; It is the calculation function of the equivalent deformation pressure height value considering the surrounding rock level; is the tunnel span correction factor; For the surrounding rock level, such as level III surrounding rock ; is the calculation function of the tunnel span correction coefficient; is the tunnel span, m; S43. Through the analysis of the lateral pressure coefficient, the lateral pressure coefficient of the surrounding rock deformation pressure approximately obeys the normal distribution function, and then the distribution value of the lateral pressure coefficient under each probability condition is obtained through the probability density function; S44. Considering the structural safety, the lateral pressure coefficient range is corrected. After correction, the calculation method of horizontal deformation pressure is obtained. The formula is as follows: ; in, It is the calculation function of the horizontal deformation pressure of the surrounding rock considering the surrounding rock level; is the horizontal deformation pressure value of surrounding rock considering the surrounding rock level, Pa; is the lateral pressure coefficient.

[0010] Preferably, according to the method for calculating the deformation pressure of the early high-strength shotcrete layer of the tunnel considering the surrounding rock level established in S4, the rock mass quality indicators corresponding to different surrounding rock levels are Value is a range.

[0011] Preferably, in S5, the specific steps of establishing a method for calculating the surrounding rock deformation pressure of the early high-strength shotcrete layer of the tunnel taking into account the rock mass quality index include: S51, establish The indicator is a variable Systematic surrounding rock deformation pressure calculation method; S52, according to the surrounding rock level and The corresponding relationship of the values ​​is to divide the same surrounding rock grade into n equal parts. The values ​​are also divided into n equal parts and analyzed by linear regression to obtain the The deformation pressure calculation expression of the value is as follows: ; ; ; in, To consider the rock mass quality index Calculation function of surrounding rock grade; It is an indicator of rock mass quality; To consider the rock mass quality index The vertical deformation pressure value of surrounding rock; To consider the rock mass quality index The calculation function of the vertical deformation pressure of the surrounding rock; To consider the rock mass quality index Horizontal deformation pressure value of surrounding rock; To consider the rock mass quality index The calculation function of the horizontal deformation pressure of the surrounding rock; S53, according to The corresponding relationship between the value and other rock mass quality indicators is established. , , The calculation expressions of the three classification index values ​​are as follows: ; ; ; in, It is an indicator of rock mass quality; Rock mass quality index The calculation function of It is an indicator of rock mass quality; Rock mass quality index The calculation function of It is an indicator of rock mass quality; Rock mass quality index The calculation function of S54. According to the conversion relationship between various rock mass quality indicators, the deformation pressure calculation expression based on different rock mass quality indicators is obtained, and the formula is as follows: ; ; ; in, for The vertical deformation pressure of the surrounding rock corresponding to the system; for The calculation function of the vertical deformation pressure of the surrounding rock corresponding to the system; H is the tunnel burial depth, m; for The vertical deformation pressure of the surrounding rock corresponding to the system; for The calculation function of the vertical deformation pressure of the surrounding rock corresponding to the system; is the number of rock mass volume joints, number / m 3 ; for The vertical deformation pressure of the surrounding rock corresponding to the system; for The calculation function of the vertical deformation pressure of the surrounding rock corresponding to the system; is the tunnel diameter, m; the horizontal deformation pressure of the surrounding rock is calculated based on the lateral pressure coefficient and the vertical deformation pressure of the surrounding rock.

[0012] Preferably, in S6, the specific steps of establishing a method for calculating the surrounding rock deformation pressure of a tunnel in a high-strength shotcrete layer taking into account the construction level are as follows: S61. According to the deformation pressure sample database, the deformation pressure of the surrounding rock under different construction methods is analyzed. According to the surrounding rock level, the influence of the tunnel span is comprehensively considered, and the construction level influence coefficient under different surrounding rock levels is calculated. The formula is as follows: ; in, is the construction level influence coefficient; is the calculation function of the construction level influence coefficient; is the measured mean value of vertical deformation pressure of conventional mechanized partial excavation tunnel construction, Pa; is the measured mean value of vertical deformation pressure of large-scale mechanized large-section construction tunnel, Pa; S62. Based on the obtained construction level influence coefficient, the calculation method of the vertical deformation pressure of the surrounding rock considering the influence of the tunnel construction level is used. The calculation method of the horizontal deformation pressure of the surrounding rock is obtained by converting the lateral pressure coefficient and the vertical deformation pressure of the surrounding rock. The formula is as follows: ; in, is the vertical deformation pressure of the surrounding rock taking into account the influence coefficient of construction level; It is the calculation function of the vertical deformation pressure of the surrounding rock taking into account the influence coefficient of construction level.

[0013] Preferably, the specific steps of establishing a method for calculating the surrounding rock deformation pressure of the early high-strength shotcrete layer of the tunnel considering the time and space effects in S7 include: S71. A correction coefficient is proposed to characterize the temporal and spatial variation of deformation pressure, thereby obtaining a calculation method for surrounding rock deformation pressure that takes temporal and spatial effects into consideration. The formula is as follows: ; in, is the vertical deformation pressure value of surrounding rock considering time and space effect, Pa; It is the calculation function of the vertical deformation pressure of surrounding rock considering the time and space effect; is the correction coefficient of deformation pressure changing with time and space; is the deformation pressure value of surrounding rock; S72. Using the literature research method, a calculation method for the correction coefficient of deformation pressure changing with time and space is proposed. The formula is as follows: ; ; in, To calculate the constant value; is the correction coefficient of deformation pressure changing with time and space; for The calculation function of is the plastic zone radius of the surrounding rock, m, which is obtained based on the classical elastic-plastic theory solution or on-site measurement; is the radius of the tunnel, m; It is the calculation function of the correction coefficient of deformation pressure changing with time and space; is the distance from the tunnel face, m.

[0014] Preferably, in S8, the specific steps of proposing a tunnel early high-strength shotcrete layer safety evaluation method include: S81. Propose the safety factor control value of shotcrete according to the railway tunnel design specification K ; S82. According to the calculation model of the early high-strength shotcrete layer of the tunnel and the calculation method of the surrounding rock deformation pressure, the bending moment and axial force of the shotcrete layer are calculated, and the safety factor of the shotcrete layer is converted. The formula is as follows: ; ; in, is the safety factor when the shotcrete layer is under pressure; is the calculation function of the compressive safety factor of the shotcrete layer; is the ultimate compressive strength of shotcrete, kPa; is the ultimate tensile strength of shotcrete, kPa; N is the axial force of the shotcrete layer, kN; is the longitudinal depth of the shotcrete layer, m; is the height of the shotcrete layer, m; is the radial safety factor of shotcrete under pressure; is the calculation function of the tensile safety factor of shotcrete; is the bending moment of the shotcrete layer, kN·m.

[0015] Therefore, the present invention adopts the above-mentioned railway tunnel high-performance active support system design method considering the time and space effects, and the beneficial effects are as follows: The present invention combines the surrounding rock deformation pressure calculation method that takes into account the surrounding rock grade, rock mass quality indicators, construction level and time and space effects, and through the shotcrete safety evaluation method, obtains a tunnel early high-strength shotcrete layer design method with a clear and rigorous calculation process, a simple and easy-to-understand calculation formula, a simple and efficient calculation process, and an accurate and highly reliable calculation result. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a flow chart of an embodiment of a design method for a high-performance active support system for a railway tunnel taking into account time and space effects of the present invention; Figure 2 It is a calculation model of the early high-strength shotcrete layer of a tunnel in an embodiment of the design method of a high-performance active support system for a railway tunnel considering time and space effects of the present invention; Figure 3 It is a schematic diagram of the vertical and horizontal decomposition of the surrounding rock deformation pressure of an embodiment of the design method of a high-performance active support system for a railway tunnel taking into account the time and space effects of the present invention. DETAILED DESCRIPTION

[0017] The technical solution of the present invention is further described below through the accompanying drawings and embodiments.

[0018] Unless otherwise defined, technical or scientific terms used in the present invention shall have the common meanings understood by one having ordinary skills in the field to which the present invention belongs.

[0019] Example like Figure 1 As shown in the figure, the design method of high-performance active support system for railway tunnels considering time and space effects includes the following specific steps: S1. Establish a calculation model for early high-strength shotcrete layer in tunnels.

[0020] like Figure 2 As shown in the figure, in the calculation model of the early high-strength shotcrete layer of the tunnel, the early high-strength shotcrete structure is simulated by beam elements, the interaction between the early high-strength shotcrete and the stratum is simulated by radial tension-free springs and tangential springs, and the bottom of the model is fixed by fixed end constraints.

[0021] S2. Determine the calculation parameters required for the shotcrete calculation model based on the early high-strength shotcrete calculation model of the tunnel. The specific steps are as follows: S21. According to the hardening characteristics of shotcrete and the timeliness of its mechanical properties, the calculation method of strength parameters and deformation parameters of the early high-strength shotcrete layer of the tunnel considering the time and space effects is determined. The formula is as follows: ; ; in, is time, s; For the early high-strength shotcrete layer of the tunnel Moment intensity, Pa; is the strength of the early high-strength shotcrete layer of the tunnel at the initial moment, Pa; For the early high-strength shotcrete layer of the tunnel The elastic modulus at the moment, Pa, is a constant of 2.72; and is the time constant.

[0022] S22. Determine the spring reaction coefficient of the early high-strength shotcrete layer of the tunnel according to the specification or indoor test. In the absence of tests, the radial spring stiffness parameter between the shotcrete and the surrounding rock can be selected according to the elastic reaction coefficient specified in the "Railway Tunnel Design Code" (TB10003-2016); the tangential spring stiffness coefficient is 1 / 2 of the radial spring stiffness coefficient. In the case of tests, it can be selected according to the actual test results.

[0023] S3. Determine the factors affecting the surrounding rock deformation pressure on the early high-strength shotcrete layer of the tunnel. The specific steps are as follows: S31. Through field measurements and literature research methods, a deformation pressure sample database considering different regions, time periods, and construction methods is formed, and the database is classified according to different surrounding rock levels, tunnel spans, and construction methods to analyze the characteristics and influencing factors of deformation pressure; S32. According to the analysis of the deformation pressure sample database, it is determined that the influencing factors of deformation pressure include surrounding rock grade, tunnel span, construction level, rock mass quality index and time and space effect.

[0024] S4. Establish a method for calculating the surrounding rock deformation pressure of the early high-strength shotcrete layer of the tunnel considering the surrounding rock level. The specific steps are as follows: S41, such as Figure 3 As shown in FIG. 1 , the data of the deformation pressure sample database is decomposed into vertical and horizontal uniformly distributed loads according to the area equivalence principle for calculation, and distributed according to the uniformly distributed equivalent load mode.

[0025] S42. Through multi-factor analysis method, taking into account the influencing factors of tunnel surrounding rock grade and tunnel span, the vertical deformation pressure calculation formula of surrounding rock is established by fitting and deduction, and the deformation pressure calculation formula with the highest correlation coefficient is selected as the final calculation formula of vertical deformation pressure. The formula is as follows: ; ; ; in, To consider the vertical deformation pressure of surrounding rock at surrounding rock level, Pa; is the weight of the surrounding rock, kN / m 3 ; is the equivalent deformation pressure height value, m; is the tunnel span correction factor; For the surrounding rock level, such as level III surrounding rock ; is the tunnel span, m.

[0026] S43. Through the analysis of the lateral pressure coefficient, the lateral pressure coefficient of the surrounding rock deformation pressure approximately obeys the normal distribution function, and then through the probability density function, the distribution value of the lateral pressure coefficient under each probability condition is finally obtained. The deformation pressure measured on site is uneven, and the structural stress is in an unfavorable state. Therefore, considering the structural safety, the lateral pressure coefficient range is corrected. After correction, the calculation method of horizontal deformation pressure is obtained, and the formula is as follows: ; in, To consider the horizontal deformation pressure of surrounding rock of surrounding rock level, Pa; is the lateral pressure coefficient.

[0027] S5. Establish a calculation method for the surrounding rock deformation pressure of the early high-strength shotcrete layer of the tunnel taking into account the rock mass quality indicators.

[0028] According to the calculation method of deformation pressure of early high-strength shotcrete layer in tunnel considering surrounding rock level established by S4, the rock mass quality indicators corresponding to different surrounding rock levels are The value is a range, when When the value is near the boundary value of this range, it will have a great impact on the determination of the surrounding rock grade. In actual engineering applications, it tends to be conservative and often chooses to design support parameters based on the level with poor surrounding rock quality. This will lead to overly conservative support parameter design and poor economic results. In order to make up for the engineering calculation errors caused by surrounding rock pressure assessment based on surrounding rock grade as a variable, and to convert my country's rock mass quality indicators into To promote the application of the system, it is necessary to establish The calculation method of surrounding rock pressure with the index as variable is: The specific steps of the system surrounding rock pressure calculation method are as follows: S51, establish The indicator is a variable Calculation method of system surrounding rock deformation pressure.

[0029] S52, according to the surrounding rock level and The corresponding relationship of the values ​​is to divide the same surrounding rock level into n equal parts. The values ​​are also divided into n equal parts and analyzed by linear regression to obtain the The deformation pressure calculation expression of the value is as follows: ; ; ; in, It is an indicator of rock mass quality; To consider the rock mass quality index The vertical deformation pressure value of surrounding rock; To consider the rock mass quality index The horizontal deformation pressure value of the surrounding rock.

[0030] S53, according to The corresponding relationship between the value and other rock mass quality indicators is established. 、 、 The calculation expressions of the three classification index values ​​are as follows: ; ; ; in, It is an indicator of rock mass quality; It is an indicator of rock mass quality; It is an indicator of rock mass quality.

[0031] S54. According to the conversion relationship between various rock mass quality indicators, the deformation pressure calculation expression based on different rock mass quality indicators is obtained, and the formula is as follows: ; ; ; in, for The vertical deformation pressure of the surrounding rock corresponding to the system; is the tunnel burial depth, m; for The vertical deformation pressure of the surrounding rock corresponding to the system; is the number of rock mass volume joints, number / m 3 ; for The vertical deformation pressure of the surrounding rock corresponding to the system; is the tunnel diameter, m; note that the horizontal deformation pressure of the surrounding rock can be calculated based on the lateral pressure coefficient and the vertical deformation pressure of the surrounding rock.

[0032] S6. Establish a calculation method for the surrounding rock deformation pressure of the early high-strength shotcrete layer of the tunnel taking into account the construction level. The specific steps are as follows: S61. According to the established deformation pressure sample database, the deformation pressure of the surrounding rock under different construction methods is analyzed. According to the surrounding rock level, the influence of the tunnel span is comprehensively considered, and the construction level influence coefficient under different surrounding rock levels is calculated. The formula is as follows: ; in, is the construction level influence coefficient. Under large-scale mechanized large-section excavation construction, the values ​​of surrounding rock of levels III, IV, and V are 1.0, 1.0, and 1.0, respectively. Under conventional mechanized partial excavation construction, the values ​​of surrounding rock of levels III, IV, and V are 1.0, 1.1, and 1.15, respectively. is the measured mean value of vertical deformation pressure of conventional mechanized partial excavation tunnel construction, Pa; It is the measured average value of vertical deformation pressure of large-scale mechanized large-section construction tunnel, Pa.

[0033] S62. Based on the obtained construction level influence coefficient, the calculation method of the vertical deformation pressure of the surrounding rock considering the influence of the tunnel construction level is used. The calculation method of the horizontal deformation pressure of the surrounding rock is still obtained by converting the lateral pressure coefficient and the vertical deformation pressure of the surrounding rock: ; in, It is the vertical deformation pressure of surrounding rock taking into account the influence coefficient of construction level.

[0034] S7. Establish a calculation method for the surrounding rock deformation pressure of the early high-strength shotcrete layer of the tunnel considering the time and space effects. The specific steps are as follows: S71. In actual projects, the surrounding rock pressure has the characteristics of temporal and spatial variation. As the face continues to move forward, it gradually increases and eventually reaches a stable state. Therefore, before the surrounding rock pressure reaches a stable state, a certain construction time is required. At the same time, after the sprayed layer structure is constructed, due to the influence of the age of the sprayed concrete, its mechanical properties and the resulting support effect have a certain timeliness. It can be seen that the temporal and spatial effects should be considered when calculating the deformation pressure of the surrounding rock. In order to describe the changing characteristics of the deformation pressure with time and space, a correction coefficient characterizing the change of the deformation pressure with time and space is proposed, thereby obtaining a calculation method for the deformation pressure of the surrounding rock considering the temporal and spatial effects. The formula is as follows: ; in, is the vertical deformation pressure value of surrounding rock considering time and space effect, Pa; is the correction coefficient of deformation pressure changing with time and space; is the vertical deformation pressure value of surrounding rock.

[0035] S72. Using the literature research method, a calculation method for the correction coefficient of deformation pressure changing with time and space is proposed. The formula is as follows: ; ; in, To calculate the constant value; is the correction coefficient of deformation pressure changing with time and space; is the plastic zone radius of the surrounding rock (can be obtained based on the classical elastic-plastic theory solution or on-site measurement), m; is the radius of the tunnel, m; is the distance from the tunnel face, m.

[0036] S8. A method for evaluating the safety and durability of shotcrete is proposed. The specific steps are as follows: S81. Propose the safety factor control value of shotcrete according to the specification K .

[0037] S82. According to the calculation model of the early high-strength shotcrete layer of the tunnel and the calculation method of the deformation pressure of the surrounding rock, the bending moment and axial force of the shotcrete layer are calculated, and the safety factor of the shotcrete layer is converted. The formula is as follows: ; ; in, is the safety factor when the shotcrete layer is under pressure, is the ultimate compressive strength of shotcrete, kPa; is the ultimate tensile strength of shotcrete, kPa; N is the axial force of the shotcrete layer; is the longitudinal depth of the shotcrete layer, m; is the height of the shotcrete layer, m; is the radial safety factor of shotcrete under pressure; is the bending moment of the shotcrete layer, kN·m.

[0038] S9. Determine the safety of shotcrete based on the calculation results of the tunnel early high-strength shotcrete layer calculation model.

[0039] S10. Determine the design parameters of shotcrete based on the calculation results of the early high-strength shotcrete layer of the tunnel.

[0040] Therefore, the present invention adopts the above-mentioned railway tunnel high-performance active support system design method considering time and space effects, based on the calculation model of the early high-strength shotcrete layer of the tunnel, combined with the surrounding rock deformation pressure calculation method considering the surrounding rock grade, rock mass quality index, construction level and time and space effects, and through the shotcrete safety evaluation method, the design method of the early high-strength shotcrete layer of the tunnel is obtained. The safety of the early high-strength shotcrete layer of the tunnel under different support parameters can be simply, quickly and accurately calculated. Ordinary designers can use this method to design tunnel projects using active shotcrete support, which has good engineering value.

[0041] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A design method for a high-performance active support system for railway tunnels considering time and space effects, characterized in that: The following steps are involved: S1. Establish a calculation model for early high-strength shotcrete layer in tunnels; S2. Determine the calculation parameters required for the shotcrete calculation model based on the early high-strength shotcrete calculation model of the tunnel; S3. Determine the factors affecting the deformation pressure of the surrounding rock on the early high-strength shotcrete layer of the tunnel; S4. Establish a method for calculating the surrounding rock deformation pressure of the early high-strength shotcrete layer of the tunnel taking into account the surrounding rock level; S5. Establish a calculation method for surrounding rock deformation pressure of early high-strength shotcrete layer in tunnels taking into account rock mass quality indicators; S6. Establish a calculation method for the surrounding rock deformation pressure of a tunnel in a high-strength shotcrete layer taking into account the construction level; S7. Establish a calculation method for the surrounding rock deformation pressure of the early high-strength shotcrete layer of the tunnel considering the time and space effects; S8. Propose a safety evaluation method for early high-strength shotcrete layer in tunnels; S9. Determine the safety of shotcrete based on the calculation results of the early high-strength shotcrete layer calculation model of the tunnel; S10. Determine the shotcrete design parameters based on the calculation results of the early high-strength shotcrete layer of the tunnel.

2. The design method of a high-performance active support system for a railway tunnel considering time and space effects according to claim 1 is characterized in that: In S1, the early high-strength shotcrete structure in the calculation model of the early high-strength shotcrete layer of the tunnel is simulated by beam elements, the interaction between the early high-strength shotcrete and the stratum is simulated by radial tension-free springs and tangential springs, and the bottom of the model is fixed by fixed-end constraints.

3. The design method of a high-performance active support system for a railway tunnel considering time and space effects according to claim 2 is characterized in that: In S2, the specific steps of determining the calculation parameters required for the shotcrete calculation model according to the early high-strength shotcrete calculation model of the tunnel include: S21. According to the hardening characteristics of shotcrete and the timeliness of its mechanical properties, the calculation method of strength parameters and deformation parameters of the early high-strength shotcrete layer of the tunnel considering the time and space effects is determined. The formula is as follows: ； ； in, is the calculation function of the change of the strength of the early high-strength shotcrete layer of the tunnel with time; is time, s; For the early high-strength shotcrete layer of the tunnel Moment intensity, Pa; is the strength of the early high-strength shotcrete layer of the tunnel at the initial moment, Pa; is the calculation function of the elastic modulus of the early high-strength shotcrete layer of the tunnel changing with time; For the early high-strength shotcrete layer of the tunnel Elastic modulus at the moment, Pa; For the early high-strength shotcrete layer of the tunnel t Elastic modulus at the moment, Pa; is the elastic modulus of the early high-strength shotcrete layer of the tunnel at the initial moment, Pa; S22. Determine the spring reaction coefficient of the early high-strength shotcrete layer of the tunnel according to the railway tunnel design specifications or indoor experiments. In the absence of tests, the radial spring stiffness parameters between the shotcrete and the surrounding rock shall be selected according to the elastic reaction coefficient specified in the railway tunnel design specifications; the tangential spring stiffness coefficient shall be 1 / 2 of the radial spring stiffness coefficient.

4. The design method of a high-performance active support system for a railway tunnel considering time and space effects according to claim 3 is characterized in that: In S3, the specific steps of determining the factors affecting the surrounding rock deformation pressure on the early high-strength shotcrete layer of the tunnel include: S31. Through field measurements and literature research methods, a deformation pressure sample database considering different regions, time periods, and construction methods is formed, and the database is classified according to different surrounding rock levels, tunnel spans, and construction methods to analyze the characteristics and influencing factors of deformation pressure; S32. Determine the influencing factors of deformation pressure according to the deformation pressure sample database analysis; the influencing factors include surrounding rock grade, tunnel span, construction level, rock mass quality index and time-space effect.

5. The design method of a high-performance active support system for a railway tunnel considering time and space effects according to claim 4 is characterized in that: In S4, the specific steps of establishing a method for calculating the surrounding rock deformation pressure of the early high-strength shotcrete layer of a tunnel considering the surrounding rock level include: S41, decomposing the data of the deformation pressure sample database into vertical and horizontal uniformly distributed loads according to the area equivalence principle for calculation, and distributing them according to a uniformly distributed equivalent load mode; S42. Through multi-factor analysis method, taking into account the influencing factors of tunnel surrounding rock grade and tunnel span, the vertical deformation pressure calculation formula of surrounding rock is established by fitting and deduction, and the deformation pressure calculation formula with the highest correlation coefficient is selected as the final calculation formula of vertical deformation pressure. The formula is as follows: ； ； ； in, is the calculation function of the vertical deformation pressure of the surrounding rock considering the surrounding rock level; is the vertical deformation pressure value of surrounding rock considering the surrounding rock level, Pa; is the weight of the surrounding rock, kN / m 3 ; is the equivalent deformation pressure height value, m; It is the calculation function of the equivalent deformation pressure height value considering the surrounding rock level; is the tunnel span correction factor; For the surrounding rock level, such as level III surrounding rock ; is the calculation function of the tunnel span correction coefficient; is the tunnel span, m; S43. Through the analysis of the lateral pressure coefficient, the lateral pressure coefficient of the surrounding rock deformation pressure approximately obeys the normal distribution function, and then the distribution value of the lateral pressure coefficient under various probability conditions is obtained through the probability density function; S44. Considering the structural safety, the lateral pressure coefficient range is corrected. After correction, the calculation method of horizontal deformation pressure is obtained. The formula is as follows: ； in, It is the calculation function of the horizontal deformation pressure of the surrounding rock considering the surrounding rock level; is the horizontal deformation pressure value of surrounding rock considering the surrounding rock level, Pa; is the lateral pressure coefficient.

6. The design method of a high-performance active support system for a railway tunnel considering time and space effects according to claim 5 is characterized in that: According to the calculation method of deformation pressure of early high-strength shotcrete layer in tunnel considering surrounding rock level established in S4, the rock mass quality indicators corresponding to different surrounding rock levels are Value is a range.

7. The design method of a high-performance active support system for a railway tunnel considering time and space effects according to claim 6 is characterized in that: In S5, the specific steps of establishing a method for calculating the surrounding rock deformation pressure of the early high-strength shotcrete layer of the tunnel considering the rock mass quality index include: S51, establish The indicator is a variable Systematic surrounding rock deformation pressure calculation method; S52, according to the surrounding rock level and The corresponding relationship of the values ​​is to divide the same surrounding rock grade into n equal parts. The values ​​are also divided into n equal parts and analyzed by linear regression to obtain The deformation pressure calculation expression of the value is as follows: ； ； ； in, To consider the rock mass quality index Calculation function of surrounding rock grade; It is an indicator of rock mass quality; To consider the rock mass quality index The vertical deformation pressure value of surrounding rock; To consider the rock mass quality index The calculation function of the vertical deformation pressure of the surrounding rock; To consider the rock mass quality index Horizontal deformation pressure value of surrounding rock; To consider the rock mass quality index The calculation function of the horizontal deformation pressure of the surrounding rock; S53, according to The corresponding relationship between the value and other rock mass quality indicators is established. RMR, Q, GSI The calculation expressions of the three classification index values ​​are as follows: ； ； ； in, It is an indicator of rock mass quality; Rock mass quality index The calculation function of It is an indicator of rock mass quality; Rock mass quality index The calculation function of It is an indicator of rock mass quality; Rock mass quality index The calculation function of S54. According to the conversion relationship between various rock mass quality indicators, the deformation pressure calculation expression based on different rock mass quality indicators is obtained, and the formula is as follows: ； ； ； in, for RMR The vertical deformation pressure of the surrounding rock corresponding to the system; for RMR The calculation function of the vertical deformation pressure of the surrounding rock corresponding to the system; H is the tunnel burial depth, m; for The vertical deformation pressure of the surrounding rock corresponding to the system; for The calculation function of the vertical deformation pressure of the surrounding rock corresponding to the system; is the number of rock mass volume joints, number / m 3 ; for The vertical deformation pressure of the surrounding rock corresponding to the system; for The calculation function of the vertical deformation pressure of the surrounding rock corresponding to the system; is the tunnel diameter, m; the horizontal deformation pressure of the surrounding rock is calculated based on the lateral pressure coefficient and the vertical deformation pressure of the surrounding rock.

8. The design method of a high-performance active support system for a railway tunnel considering time and space effects according to claim 7 is characterized in that: In S6, the specific steps of establishing a method for calculating the surrounding rock deformation pressure of a tunnel in a high-strength shotcrete layer taking into account the construction level are as follows: S61. According to the deformation pressure sample database, the deformation pressure of the surrounding rock under different construction methods is analyzed. According to the surrounding rock level, the influence of the tunnel span is comprehensively considered, and the construction level influence coefficient under different surrounding rock levels is calculated. The formula is as follows: ； in, is the construction level influence coefficient; is the calculation function of the construction level influence coefficient; is the measured mean value of vertical deformation pressure of conventional mechanized partial excavation tunnel construction, Pa; is the measured mean value of vertical deformation pressure of large-scale mechanized large-section construction tunnel, Pa; S62. Based on the obtained construction level influence coefficient, the calculation method of the vertical deformation pressure of the surrounding rock considering the influence of the tunnel construction level is used. The calculation method of the horizontal deformation pressure of the surrounding rock is obtained by converting the lateral pressure coefficient and the vertical deformation pressure of the surrounding rock. The formula is as follows: ； in, is the vertical deformation pressure of the surrounding rock taking into account the influence coefficient of construction level; It is the calculation function of the vertical deformation pressure of the surrounding rock taking into account the influence coefficient of construction level.

9. The design method of a high-performance active support system for a railway tunnel considering time and space effects according to claim 7 is characterized in that: In S7, the specific steps of establishing a calculation method for the surrounding rock deformation pressure of the early high-strength shotcrete layer of the tunnel considering the time and space effects include: S71. A correction coefficient is proposed to characterize the temporal and spatial variation of deformation pressure, thereby obtaining a calculation method for surrounding rock deformation pressure that takes temporal and spatial effects into consideration. The formula is as follows: ； in, is the vertical deformation pressure value of surrounding rock considering time and space effect, Pa; It is the calculation function of the vertical deformation pressure of surrounding rock considering the time and space effect; is the correction coefficient of deformation pressure changing with time and space; is the deformation pressure value of surrounding rock; S72. Using the literature research method, a calculation method for the correction coefficient of deformation pressure changing with time and space is proposed. The formula is as follows: ； ； in, To calculate the constant value; is the correction coefficient of deformation pressure changing with time and space; for The calculation function of is the plastic zone radius of the surrounding rock, m, which is obtained based on the classical elastic-plastic theory solution or on-site measurement; is the tunnel radius, m; It is the calculation function of the correction coefficient of deformation pressure changing with time and space; is the distance from the tunnel face, m.

10. The design method of a high-performance active support system for a railway tunnel considering time and space effects according to claim 9 is characterized in that: In S8, the specific steps of the safety evaluation method of early high-strength shotcrete layer in tunnels are proposed, including: S81. Propose the safety factor control value of shotcrete according to the railway tunnel design specification K ; S82. According to the calculation model of the early high-strength shotcrete layer of the tunnel and the calculation method of the surrounding rock deformation pressure, the bending moment and axial force of the shotcrete layer are calculated, and the safety factor of the shotcrete layer is converted. The formula is as follows: ； ； in, is the safety factor when the shotcrete layer is under pressure; is the calculation function of the compressive safety factor of the shotcrete layer; is the ultimate compressive strength of shotcrete, kPa; is the ultimate tensile strength of shotcrete, kPa; N is the axial force of the shotcrete layer, kN; is the longitudinal depth of the shotcrete layer, m; is the height of the shotcrete layer, m; is the radial safety factor of shotcrete under pressure; is the calculation function of the tensile safety factor of shotcrete; is the bending moment of the shotcrete layer, kN·m.

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