Construction scheme feasibility evaluation method considering cyclic blasting accumulated damage

Abstract

The invention relates to a construction scheme feasibility evaluation method considering cyclic blasting accumulated damage. The method comprises the following steps: establishing a cyclic blasting accumulated damage model according to a fatigue damage effect caused by an impact effect of a blasting load borne by a drilling and blasting method in a tunnel surrounding rock damage area; a plurality of blast holes are formed in the to-be-constructed area, and sound wave detectors are arranged on the two sides of the blast holes; blasting in the blast hole, recording sound waves generated by blasting through the sound wave detector, and calculating a damage value of the construction area through the cyclic blasting accumulated damage model according to the sound waves; and establishing a numerical calculation model, substituting the damage value into the numerical calculation model, and generating a feasibility evaluation report through the numerical calculation model.

Description

Technical Field

[0001] The present invention relates to the technical field of construction engineering, and particularly to a method for evaluating the feasibility of a construction plan considering cumulative damage caused by cyclic blasting. Background Art

[0002] During the process of engineering construction, the force characteristics and the conversion of balanced force systems and moments are very complex. Therefore, it is not easy to analyze and evaluate the comprehensive stability of engineering structures during the construction process. The limit equilibrium method is a relatively commonly used method for engineering stability analysis. Based on geometric assumptions, this method calculates the safety factor according to a known or assumed slip surface, but it requires this slip surface to be regular. The limit equilibrium method calculates the safety factor based on a regular slip surface on the basis of geometric assumptions, and has a relatively high calculation efficiency. However, it ignores the constitutive relationship of rock and soil during the instability process, and the relatively cumbersome calculation process is not conducive to the popularization and application of this method. A large number of studies have shown that the strength reduction method has more advantages than the traditional limit equilibrium method and can consider the stress, constitutive relationship, deformation of the engineering body, and the action effect of excavation and support structures. Currently, many scholars in this field have analyzed and discussed the strength reduction method, and combined with engineering application research, which has effectively promoted the improvement and application of this method. The strength reduction method finds the ultimate state of the project by reducing the strength parameters of rock and soil, and thus realizes the calculation of the safety factor. This method is also applicable to the stability analysis of tunnel engineering. Based on the idea of the strength reduction method, a dynamic strength reduction method based on Hoek-Brown for simulating the progressive failure of the project is proposed. By continuously and dynamically reducing the strength parameters of the damaged area, this method makes the potential slip surface gradually evolve to penetration, so as to obtain the ultimate equilibrium state of the project. The dynamic strength reduction method based on Hoek-Brown truly reproduces the process of progressive instability of the project, providing an effective way for the strength reduction method to be more effectively applied to the quantitative evaluation of engineering stability.

[0003] The degree to which the calculation model expresses engineering characteristics will directly affect the accuracy of the established learning samples, and further affect the accuracy of the optimization results of the construction plan. For projects constructed by the blasting method, the cumulative damage phenomenon of cyclic blasting excavation to the rock mass cannot be ignored, because this damage phenomenon will directly affect the evaluation results of construction stability.

[0004] Under the background that the blasting method is still widely used in engineering construction in China, the disturbance of blasting construction to the rock mass cannot be ignored. Calculating the safety factor considering blasting cumulative damage will be more conducive to the accurate evaluation of the project. Summary of the Invention

[0005] The object of the present invention is to overcome the defects of the prior art and provide a method for evaluating the feasibility of a construction plan considering cyclic blasting cumulative damage. By establishing a cyclic blasting cumulative damage model, the cumulative damage phenomenon of rock mass caused by engineering cyclic blasting construction is considered, so as to generate a feasibility evaluation report.

[0006] The technical solution to achieve the above object is a method for evaluating the feasibility of a construction plan considering cyclic blasting cumulative damage, including the following steps:

[0007] Establish a cyclic blasting cumulative damage model according to the fatigue damage effect caused by the impact of blasting load borne by the damaged area of the tunnel surrounding rock by the drill and blast method;

[0008] Drill a number of blasting holes in the area to be constructed, and set acoustic wave detectors on both sides of the blasting holes;

[0009] Conduct blasting in the blasting holes, record the acoustic waves generated by the blasting through the acoustic wave detectors, and calculate the damage value of the construction area according to the acoustic waves through the cyclic blasting cumulative damage model;

[0010] Establish a numerical calculation model, substitute the damage value into the numerical calculation model, and generate a feasibility evaluation report through the numerical calculation model.

[0011] Further, the cyclic blasting cumulative damage model is:

[0012]

[0013] Wherein, Y is the damage energy release rate; is the cumulative plastic strain rate; is the cumulative plastic strain corresponding to the damage threshold; S is a material constant; H() is the Heaviside function.

[0014] Further, the expression of the damage energy release rate Y is:

[0015]

[0016] Wherein, σ eq is the equivalent stress; R V is the three-dimensional stress degree equation; E is the elastic modulus.

[0017] Further, when blasting in the blasting holes, the damage value D b of the construction area is:

[0018]

[0019] Wherein, v0 is the acoustic wave velocity of the rock mass before blasting; v is the acoustic wave velocity of the rock mass after blasting.

[0020] Further, when blasting in the blasting holes, calculate the average pressure in the blasting holes.

[0021] Further, the average pressure P0 in the blasting holes is:

[0022]

[0023] Where ρ e is the explosive density; D is the explosive blasting velocity; d c is the charging diameter; γ is the isentropic exponent of the explosive, and x s is the diameter of the blasting hole.

[0024] Further, when establishing the numerical calculation model, establish the numerical calculation model based on the Hoek-Brown criterion.

[0025] Further, when generating the feasibility evaluation report through the numerical calculation model, obtain the initial damaged area of the construction plan by means of overall reduction of strength parameters, then reduce the strength parameters of the initial damaged area, and continuously add the newly emerged damaged areas to the reduction target, finally obtain the progressive failure process of the target structure, and record the feasibility evaluation report under the limit state.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] By establishing a cyclic blasting cumulative damage model, the cumulative damage phenomenon of rock mass caused by engineering cyclic blasting construction is considered, so as to generate a feasibility evaluation report for the construction plan. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a schematic flow chart of a method for evaluating the feasibility of a construction plan considering cyclic blasting cumulative damage;

[0029] Figure 2 is a layout effect diagram of a sonic test experiment of a method for evaluating the feasibility of a construction plan considering cyclic blasting cumulative damage;

[0030] Figure 3 is a fitting effect diagram of the blasting sonic test results of a method for evaluating the feasibility of a construction plan considering cyclic blasting cumulative damage;

[0031] Figure 4 is a flow chart of a dynamic strength reduction method of a method for evaluating the feasibility of a construction plan considering cyclic blasting cumulative damage;

[0032] Legend: 1. Cyclic blasting cumulative damage model; 2. Blasting load; 3. Blasting hole; 4. Numerical calculation model. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0033] The present invention will be further described below in conjunction with specific embodiments.

[0034] Refer to Figure 1 and Figure 2 , a method for evaluating the feasibility of a construction plan considering cyclic blasting cumulative damage, comprising the following steps:

[0035] Establish a cyclic blasting cumulative damage model 1 according to the fatigue damage effect caused by the impact of the blasting load 2 borne by the tunnel surrounding rock damage area under the drill and blast method;

[0036] Drive a number of blasting holes 3 in the area to be constructed, and arrange acoustic wave detectors on both sides of the blasting holes 3;

[0037] Conduct blasting in the blasting holes 3, record the acoustic waves generated by the blasting through the acoustic wave detectors, and calculate the damage value of the construction area according to the acoustic waves through the cyclic blasting cumulative damage model 1;

[0038] Establish a numerical calculation model 4, input the damage value into the numerical calculation model 4, and generate a feasibility evaluation report through the numerical calculation model 4.

[0039] Further, the cyclic blasting cumulative damage model 1 is:

[0040]

[0041] Where Y is the damage energy release rate; is the cumulative plastic strain rate; is the cumulative plastic strain corresponding to the damage threshold; S is a material constant; H() is the Heaviside function.

[0042] Furthermore, the expression of H() is:

[0043]

[0044] Further, the expression of the damage energy release rate Y is:

[0045]

[0046] Where σ eq is the equivalent stress; R V is the three-dimensional stress equation; E is the elastic modulus. Preferably, the expression of σ eq is

[0047] Furthermore, under the single proportional loading stress state, the expression of the cumulative plastic strain is:

[0048]

[0049] Among them, M and α are material parameters.

[0050] Deriving the above formula gives the cumulative plastic strain rate:

[0051]

[0052] According to the above formula and considering the triaxial tensile state, the damage evolution rate equation can be obtained:

[0053]

[0054] Among them, W = 2s + α, K is the bulk modulus;

[0055] Assume that each time of blasting, plastic strain will be generated in the rock stratum and show a hardening characteristic. Introduce the hardening parameter h and express it as the fatigue stress amplitude Δσ e and the power exponential function of the number of cycles N:

[0056] h = (Δσ e ) m N n

[0057] Among them, m and n are material constants;

[0058] Thus, the conversion rate equation of the cumulative damage of the rock mass under cyclic blasting can be obtained:

[0059]

[0060] Assume that the damage value of the rock mass remains unchanged within one cycle. Then, integrating the above formula over one period, the damage value within one period can be obtained as:

[0061]

[0062] Integrating the above formula and considering the integration boundary conditions:

[0063]

[0064] Among them: NF is the limit number of cyclic blasts that the rock mass can withstand.

[0065] The integral calculation gives the expression of the fatigue damage value of the rock mass:

[0066]

[0067] Assume the current N t The damage value of the cross-section under the impact of the Nth blast is Dt, and its expression is:

[0068]

[0069] Solve for NF from the above equation:

[0070]

[0071] According to the above formula, it can be obtained that:

[0072]

[0073] Due to the complexity of geological conditions, the values of W and n in the blasting cumulative damage model 1 need to be obtained by regression fitting according to the acoustic wave test data during the engineering blasting process.

[0074] Furthermore, when blasting in the blasting hole 3, the damage value D of the construction area b is:

[0075]

[0076] where v0 is the acoustic wave velocity of the rock mass before blasting; v is the acoustic wave velocity of the rock mass after blasting.

[0077] Still further, at the center position of the experimental area, a blasting hole 3 is drilled and filled with explosive in the form of coupled charge; acoustic wave monitoring holes are uniformly arranged at 2m, 4m, 6m, and 8m on both sides of the blasting hole 3 at intervals of 20cm and inclined downward at 5°, with a hole depth of 3m; before testing, the acoustic wave measuring holes are filled with water, and a ZBLU5500 type acoustic wave tester is used to record the acoustic wave conditions of each monitoring point at different blasting times, so as to calculate the damage range and damage parameters.

[0078] Furthermore, when blasting in the blasting hole 3, calculate the average pressure in the blasting hole 3.

[0079] Furthermore, the average pressure P0 in the blasting hole 3 is:

[0080]

[0081] where ρ e is the explosive density; D is the explosive blasting velocity; d c is the charge diameter; γ is the isentropic index of the explosive, and x s is the diameter of the blasting hole 3.

[0082] Still further, further calculate to obtain the equivalent blasting load 2:

[0083] P e =(2d b / a)P0

[0084] where a is the spacing between adjacent blast holes.

[0085] Further, when establishing the numerical calculation model 4, the numerical calculation model 4 is established based on the Hoek-Brown criterion.

[0086] Further, when generating the feasibility evaluation report through the numerical calculation model 4, the initial damaged area of the construction plan is obtained by means of overall reduction of strength parameters, and then the strength parameters of the initial damaged area are reduced, and the newly emerged damaged areas are continuously added to the reduction target, and finally the progressive failure process of the target structure is obtained, and the feasibility evaluation report under the limit state is recorded.

[0087] Refer to Figure 4 , still further, when generating the feasibility evaluation report through the numerical calculation model 4, according to the actual engineering characteristics, information such as modeling dimensions, material parameters, boundary conditions, and initial conditions are determined, and the numerical calculation model 4 is established. Denote the initial Hoek-Brown criterion empirical parameters as m0 and s0;

[0088] Solve for the self-weight balance of the model, and clear the current displacement field and plastic zone after the calculation is completed;

[0089] Simulate the tunnel excavation and support process, and perform the calculation balance after the tunnel excavation;

[0090] The blasting load 2 and the blasting number index (converted from construction parameters such as the hole diameter) are calculated and converted into the damage range and damage value through the Hoek-Brown-based blasting damage model. Separate groups are delimited in the numerical calculation model 4 according to the damage range, and the parameters of the damaged area elements are defined according to the damage value;

[0091] The non-proportional reduction relationship of the Hoek-Brown empirical parameters m and s is derived as:

[0092]

[0093] where λ refers to the relationship between the peak strength and the residual strength of the rock under the condition of considering the cumulative damage of cyclic blasting;

[0094] Reduce the Hoek-Brown parameters of all elements by the reduction coefficient Kd, and let:

[0095] K m = K d , m = m0 / K m , s = s0 / K s

[0096] The reduction coefficient Kd starts from 1.1 and gradually increases by 0.1 until plastic strain appears in the elements, then stop the calculation, save the current model results, and record the current reduction coefficient as j;

[0097] Traverse all elements according to the ID identifier to find the elements with plastic strain;

[0098] Use Equation (29) to specifically reduce the Hoek-Brown parameters of the elements with plastic strain, and the reduction coefficient is j = j + 0.01;

[0099] Solve the current model and determine whether there is a sudden displacement change at the key measurement points in the calculation results. If not, save the current calculation results and return to the above step to reduce the Hoek-Brown parameters of all elements with the reduction coefficient Kd, otherwise enter the following step;

[0100] End the calculation to obtain the engineering safety control index.

[0101] The following describes the usage process of a method for evaluating the feasibility of a construction plan considering cyclic blasting cumulative damage according to the present invention.

[0102] S1: Cyclic blasting cumulative damage model 1 based on the Hoek-Brown criterion

[0103] The basic expression of the Hoek-Brown criterion is:

[0104]

[0105] In the formula: σ1 and σ3 are the maximum and minimum principal stresses respectively; σ ci is the uniaxial compressive strength of the rock block; m and s are empirical parameters reflecting the hardness and fragmentation degree of the rock mass.

[0106] In Equation (1), when considering the influence of damage, the calculation methods of the Hoek-Brown empirical parameters m and s are:

[0107]

[0108] In the formula, Db is the disturbance coefficient, which is a damage result quantity.

[0109] During the construction process of the project using the drill-and-blast method, the damage zone of the tunnel surrounding rock at the fixed section in the far area of the blasting needs to repeatedly bear the impact of the blasting load 2, forming a stress cycle of loading and unloading, resulting in a fatigue damage effect. According to the theory of continuous damage mechanics, the formation rate of rock fatigue damage under blasting is:

[0110]

[0111] In the formula: Y is the damage energy release rate; is the cumulative plastic strain rate; is the cumulative plastic strain corresponding to the damage threshold; s, S are material constants; H() is the Heaviside function, and its expression is

[0112]

[0113] It is assumed that new plastic strains are generated inside the rock mass under each blasting impact, i.e., H(x) ≡ 1.

[0114] The expression for the damage energy release rate Y is:

[0115]

[0116] In the formula: σ eq is the equivalent stress, and its expression is S ij is the deviatoric stress tensor; R V is the three-dimensional stress equation; E is the elastic modulus.

[0117] Under the single proportional loading stress state, the expression for the cumulative plastic strain is:

[0118]

[0119] In the formula: M and α are material parameters.

[0120] Taking the derivative of Equation (7) gives the cumulative plastic strain rate:

[0121]

[0122] Substituting Equation (8) into Equation (4) and considering the triaxial tensile state, the damage evolution rate equation can be obtained:

[0123]

[0124] In the formula: W = 2s + α, K is the bulk modulus.

[0125] Assume that each time blasting occurs, plastic strains are generated in the rock stratum and it shows a hardening characteristic. Introduce the hardening parameter h and express it as a power exponential function of the fatigue stress amplitude Δσ e and the number of cycles N:

[0126] h = (Δσ e ) m N n (10)

[0127] In the formula: m and n are material constants.

[0128] From Equations (9) and (10), the conversion rate equation for the cumulative damage of the rock mass under cyclic blasting can be obtained:

[0129]

[0130] Assume that the damage value of the rock mass remains unchanged within a cycle. Integrating Equation (11) over one period, the damage value within one period can be obtained as follows:

[0131]

[0132] Integrate the above equation and consider the integration boundary conditions:

[0133]

[0134] In the formula: NF is the limit number of cyclic blasts that the rock mass can withstand.

[0135] The expression of the fatigue damage value of the rock mass can be obtained through integral calculation:

[0136]

[0137] Assume the current N t The damage value of the cross-section under the action of the Nth blasting impact is Dt, and its expression is:

[0138]

[0139] Solve NF from the above equation:

[0140]

[0141] Substitute Equation (16) into Equation (14) to obtain:

[0142]

[0143] Due to the complexity of geological conditions, the values of W and n in the blasting cumulative damage model 1 of Equation (17) need to be obtained through regression fitting based on the acoustic wave test data during the engineering blasting process.

[0144] S2: Acoustic wave test calibration method for cyclic blasting cumulative damage model 1

[0145] Taking the entrance section area of Jishan Tunnel in the Jingdong Tunnel Group of Puyan Expressway in Fujian Province as an example, the acoustic wave test calibration method for cyclic blasting cumulative damage model 1 is introduced.

[0146] Acoustic wave monitoring holes are uniformly arranged at an interval of 20 cm and inclined downward at 5° at 2 m, 4 m, 6 m, and 8 m on both sides of the blasting hole 3, with a hole depth of 3 m. Before the test, the acoustic wave holes are filled with water, and a ZBLU5500 type acoustic wave tester is used to record the acoustic wave conditions of each monitoring point at different blasting times, so as to calculate the damage range and damage parameters.

[0147] The average pressure of the blast hole is calculated, and the calculation method is shown in Equation (18):

[0148]

[0149] Further calculation gives the equivalent blasting load 2:

[0150] P e =(2d b / a)P0 (19)

[0151] In Equations (18) and (19), ρ e is the density of the explosive. In this case project, ρ e = 1.7 g / cm 3 ; D is the blasting velocity of the explosive. In this case project, D = 3600 m / s is taken; d c is the charge diameter. In this case project, d c = x s - 5 (mm); γ is the isentropic index of the explosive. In this case project, γ = 3 is taken; a is the spacing between adjacent blast holes. In this case project, the single - cycle footage is 0.5 m and the single - cycle explosive consumption is 28 kg.

[0152] During the blasting test, the surrounding rock damage value is calculated through Equation (20):

[0153]

[0154] where v0 is the acoustic wave velocity of the rock mass before blasting; v is the acoustic wave velocity of the rock mass after blasting.

[0155] Under the condition of the same blasting load 2, record the number of blasts and their corresponding damage values, and select any two sets of data and substitute them into Equation (17) to solve for the material coefficients W and n under the current blasting load 2 condition. Repeat this process under different blasting load 2 conditions to obtain the cumulative blasting damage calculation model under different blasting load 2 conditions as shown in Equation (21).

[0156]

[0157] Define the rock mass in the area where the sound velocity loss rate exceeds 10% as the damaged state, and the damaged area range L under different blasting load 2 conditions can be determined according to the monitoring results.

[0158] According to the result of Equation (21), under the conditions of known blasting load 2 and the number of blasts, the damaged area range and damage value can be obtained, which are applied to the division of the damaged area in the numerical calculation model 4, and the parameters of the unit bodies in the damaged area are defined according to Equations (2) and (3).

[0159] S3: Hoek - Brown dynamic strength reduction method for engineering evaluation

[0160] The above research content realizes the division of the blasting damage area and the solution of the damage value. On this basis, a dynamic strength reduction method for calculating the engineering safety index is proposed. In the calculation process, first, the overall reduction of the strength parameters is used to obtain the initial damaged area, and then only the strength parameters of the damaged area are reduced, and the newly emerged damaged areas are continuously added to the reduction target. Finally, the progressive failure process of the target structure is obtained, and the engineering safety control index under the limit state is recorded.

[0161] Compared with the previous dynamic strength reduction based on the linear strength criterion, this case proposes a dynamic strength reduction method based on the Hoek-Brown nonlinear strength criterion and the element safety factor, which reduces the two parameters m and s in the Hoek-Brown constitutive model simultaneously, effectively considering the nonlinear failure characteristics of the engineering rock mass in the tunnel portal section and having better engineering applicability.

[0162] Strength reduction means continuously reducing the strength parameters of the rock mass to make the structure reach the limit equilibrium state. The progressive cumulative failure process of the rock mass is the macroscopic manifestation of its strain-softening characteristic. Therefore, the reduction coefficient of the Hoek-Brown criterion is defined as:

[0163]

[0164] In the formula: m p , s p are the peak strength parameters in the Hoek-Brown criterion respectively; η is the strain-softening parameter, m(η) and s(η) are the post-peak strength parameters respectively. When they are the strength parameters under the engineering limit state, K m , K s are the reduction coefficients of the Hoek-Brown criterion.

[0165] In the strain-softening stage, the Hoek-Brown criterion affected by the strain-softening coefficient can be expressed as:

[0166]

[0167] In formula (23), the relationship between m(η), s(η) and η can be obtained from experiments. To simplify the problem, it is assumed that each parameter reaches the peak strength and the residual strength simultaneously, and the relationship between each parameter and the strain-softening parameter η is a piecewise linear function, and the expression is:

[0168]

[0169] In the formula: q(η) is the strength parameter; q p , q r are the peak strength parameter and the residual strength parameter respectively; η r is the softening parameter at the critical point of entering the residual strength stage.

[0170] Based on Equation (24) and the above assumptions, the relationship between the strength parameter and the softening parameter in the Hoek-Brown criterion can be obtained:

[0171]

[0172] From Equation (25), it can be obtained that:

[0173]

[0174] Substituting Equation (22) into Equation (26), it can be obtained that:

[0175]

[0176] Let It can be obtained that:

[0177]

[0178] In the formula, λ refers to the relationship between the peak strength and the residual strength of the rock under the condition of considering the cumulative damage of cyclic blasting.

[0179] Equation (28) expresses the relationship between the reduction coefficients of the empirical parameters of the Hoek-Brown criterion during the strength reduction process. For the convenience of description, the "reduction coefficient Kd" mentioned in this case all refers to the parameter K m , and K s can be calculated from Equation (28) on this basis.

[0180] Using the reduction relationship expressed by Equation (28), all the elements in the calculation model are reduced. After the calculation is balanced, the state of each element is re-evaluated, and after increasing the reduction coefficient, the plastic element bodies are reduced again. By continuously repeating this process, the dynamic strength reduction based on the Hoek-Brown criterion is completed, and the description of the gradual evolution of the potential slip surface to the penetration process is realized. The specific steps are as follows:

[0181] (1) According to the actual characteristics of the project, determine information such as the modeling size, material parameters, boundary conditions, and initial conditions, and establish a numerical calculation model 4. Denote the initial empirical parameters of the Hoek-Brown criterion as m0 and s0.

[0182] (2) Solve the self-weight balance of the model, and clear the current displacement field and plastic zone after the calculation is completed.

[0183] (3) Simulate the tunnel excavation and support process, and perform the calculation balance after the tunnel excavation.

[0184] (4) By using the methods in S1 and S2, the blasting load 2 and the blasting times index (converted from construction parameters such as blasthole diameter) are calculated and transformed into the damage range and damage value through the blasting damage model based on Hoek - Brown. Separate groups are demarcated in the numerical calculation model 4 according to the damage range, and the parameters of the damaged area elements are defined according to the damage value.

[0185] (5) Reduce the Hoek - Brown parameters of all elements by the reduction coefficient Kd. Let:

[0186] K m =K d ,m=m0 / K m ,s=s0 / K s (29)

[0187] The reduction coefficient Kd starts from 1.1 and gradually increases by 0.1 until plastic strain appears in some elements, then stop the calculation, save the current model results, and record the current reduction coefficient as j.

[0188] (6) Traverse all elements according to the ID identification to find the elements with plastic strain.

[0189] (7) Specifically reduce the Hoek - Brown parameters of the elements with plastic strain by using Equation (29), and the reduction coefficient is j = j + 0.01.

[0190] (8) Solve the current model and judge whether there is a sudden change in displacement at the key measurement points in the calculation results. If not, save the current calculation results and return to step (5); otherwise, enter step (9).

[0191] (9) End the calculation to obtain the engineering safety control index.

[0192] The method described in S3 is a calculation logic, and its actual calculation process needs to be completed with the help of a numerical calculation platform. In this case, the FLAC platform is used to implement this calculation. The following table shows the comparison between the engineering safety control index and the measured data.

[0193]

[0194]

[0195] Table 1 Verification and comparison table of the feasibility evaluation method

[0196] The present invention has been described in detail above in combination with the embodiments. Those of ordinary skill in the art can make various variations of the present invention according to the above description. Therefore, some details in the embodiments should not constitute a limitation to the present invention, and the protection scope of the present invention will be defined by the scope defined in the appended claims.

Claims

1. A feasibility evaluation method for construction plans considering cumulative damage caused by cyclic blasting, characterized in that, It includes the following steps: Establish a cyclic blasting cumulative damage model based on the fatigue damage effect caused by the impact of the blasting load borne by the damaged area of the tunnel surrounding rock under the drill and blast method; Drill a number of blast holes in the area to be constructed, and arrange acoustic wave detectors on both sides of the blast holes; Conduct blasting in the blast holes, record the acoustic waves generated by the blasting through the acoustic wave detectors, and calculate the damage value of the construction area according to the acoustic waves through the cyclic blasting cumulative damage model; Establish a numerical calculation model, input the damage value into the numerical calculation model, and generate a feasibility evaluation report through the numerical calculation model.

2. The feasibility evaluation method for a construction plan considering cyclic blasting cumulative damage according to claim 1, wherein: The cyclic blasting cumulative damage model is: where Y is the damage energy release rate; is the cumulative plastic strain rate; is the cumulative plastic strain corresponding to the damage threshold; S is a material constant; H() is the Heaviside function.

3. The feasibility evaluation method for a construction plan considering cumulative damage of cyclic blasting according to claim 2, characterized in that: The expression of the damage energy release rate Y is: Among them, σ eq is the equivalent stress; R V is the three-dimensional stress equation; E is the elastic modulus.

4. The feasibility evaluation method for a construction plan considering cyclic blasting cumulative damage according to claim 1 is characterized in that: in When blasting in the blasting holes, the damage value D of the construction area b is: Among them, v0 is the acoustic wave velocity of the rock mass before blasting; v is the acoustic wave velocity of the rock mass after blasting.

5. The feasibility evaluation method for a construction plan considering cyclic blasting cumulative damage according to claim 1, characterized in that: When conducting blasting in the blast holes, calculate the average pressure in the blast holes.

6. A method for evaluating the feasibility of a construction plan considering cyclic blasting cumulative damage according to claim 5, characterized in that: The average pressure P0 in the blast holes is: Among them, ρ e is the explosive density; D is the explosive detonation velocity; d c is the charge diameter; γ is the isentropic exponent of the explosive, and x s is the diameter of the blasting hole.

7. A method for evaluating the feasibility of a construction plan considering cyclic blasting cumulative damage according to claim 1, characterized in that: When establishing the numerical calculation model, establish the numerical calculation model based on the Hoek-Brown criterion.

8. The feasibility evaluation method for a construction plan considering cyclic blasting cumulative damage according to claim 1 is characterized in that: at When generating a feasibility evaluation report through the numerical calculation model, obtain the initial damaged area of the construction plan by means of overall reduction of strength parameters, then reduce the strength parameters of the initial damaged area, and continuously add the newly emerged damaged areas to the reduction target, finally obtain the progressive failure process of the target structure, and record the feasibility evaluation report under the limit state.

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