Inversion method for tunnel drill-and-blast construction blasting load curve based on discrete element method

Abstract

The application discloses a kind of inversion methods of tunnel drill and blast method construction blasting load curve based on discrete element method, it is related to tunnel blasting technique numerical simulation technical field, specifically in solving the problem that discrete element method is applied to the design and optimization of tunnel blasting load in background technology, realize the significant problem of tunnel drill and blast method construction, by designing a kind of inversion methods of tunnel drill and blast method construction blasting load curve based on discrete element method, the method is combined with high-precision rock mechanics model and advanced optimization algorithm, from actual blasting result, the best blasting load parameter is accurately inverted, using the method of the application will significantly improve the safety and economy of tunnel drill and blast method construction, it has important practical significance and wide application prospect to tunnel engineering field.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of numerical simulation of tunnel blasting, and particularly relates to an inversion method of blasting load curve for tunnel drill-and-blast method construction based on discrete element method. BACKGROUND

[0002] With the progress of tunnel construction technology, drill-and-blast method as a widely used tunnel construction technology, its safety, economy and construction efficiency are constantly improved. Traditional blasting load design often relies on empirical formula, which provides design convenience to some extent, but often cannot accurately reflect the blasting effect under complex geological conditions, resulting in increased construction safety risk and cost.

[0003] Discrete element method (DEM) as a numerical analysis tool for simulating the mechanical behavior of granular materials can simulate the rock fracture and blasting process at the microscopic level, providing the possibility for accurate prediction of blasting effect. Therefore, it is of great significance to apply discrete element method to the design and optimization of tunnel blasting load.

[0004] Therefore, it is urgent to design an inversion method of blasting load curve for tunnel drill-and-blast method construction based on discrete element method, which can significantly improve the safety and economy of tunnel drill-and-blast method construction, SUMMARY

[0005] In view of the problem that discrete element method is applied to the design and optimization of tunnel blasting load, which is of great significance to tunnel drill-and-blast method construction, the purpose of the present application is to provide an inversion method of blasting load curve for tunnel drill-and-blast method construction based on discrete element method, which can accurately invert the best blasting load parameters from the actual blasting results by combining high-precision rock mechanics model and advanced optimization algorithm. The use of the present application method can significantly improve the safety and economy of tunnel drill-and-blast method construction, and has important practical significance and wide application prospect in the field of tunnel engineering.

[0006] In order to achieve the above purpose, the technical solution adopted by the present application is as follows:

[0007] The inversion method of blasting load curve for tunnel drill-and-blast method construction based on discrete element method, characterized in that:

[0008] 1. The inversion method of blasting load curve for tunnel drill-and-blast method construction based on discrete element method, characterized in that:

[0009] S1. Establish a discrete element rock mass model with appropriate size according to the size of the tunnel and rock mass, and determine the macroscopic physical parameters of the rock through laboratory test;

[0010] S2. Reestablish the discrete element rock mass model, and perform laboratory tests based on the macroscopic physical parameters of the rock to obtain the microscopic parameters of the granular rock mass, wherein the microscopic parameters of the granular rock mass are obtained based on the stress-strain curve;

[0011] S3. Select a typical section representing the surrounding rock grade based on the stress-strain curve of step S2, then obtain the joint occurrence information of the typical section in the field, and perform a blasting test according to the blasting scheme to obtain the blasting scheme information, and use a laser scanner to determine the overbreak and underbreak values Z of different positions of the tunnel obs ;

[0012] S4. Create a new discrete element rock mass model, and based on the model, perform inversion calculation according to the joint occurrence information and the blasting scheme information obtained in step S3;

[0013] S5. Based on the overbreak and underbreak values Z obs , compare the results after actual blasting with the results after inversion calculation, and determine whether to output or proceed to the next step;

[0014] S6. Use the gradient descent method to achieve the minimization of the objective function, and use the iterative formula to iteratively update the peak value B of the blasting load in the numerical simulation; wherein after each iteration, the updated peak value B of the blasting load is used to run the simulation, calculate the new error, and output the blasting load curve until the calculated error is within an acceptable range.

[0015] Preferably, in step S4, the actual blasting and inversion calculation comparison is based on the calculation of the sum of squares of errors at the same position, and the formula for calculating the sum of squares of errors at the same position is:

[0016]

[0017] Wherein Obj(B) is the sum of squares of errors between the numerical simulation value and the actual value, Z obs,i is the actual overbreak and underbreak value at the i-th point, S sim,i is the numerical simulation overbreak and underbreak value at the i-th point.

[0018] Preferably, in step S6, the expression of the iterative formula is:

[0019]

[0020] Wherein, α is the step size, is the gradient with respect to the objective function B; α is the calculation step size, B NEW is the updated peak value B of the blasting load.

[0021] Preferably, The calculation formula is:

[0022]

[0023] wherein b k is the kth element in parameter B, is the partial derivative symbol, B is the peak value of blasting load, e k is the standard basis vector, and ∈ is a number that approaches 0 infinitely.

[0024] A second object of the present application is to provide a discrete element method-based inversion system for a blasting load curve in tunnel drilling and blasting construction, characterized in comprising:

[0025] A first parameter acquisition module is configured to establish a discrete element rock mass model with a proper size according to the size of a tunnel and a rock mass, and to determine macroscopic physical parameters of the rock mass through an indoor test;

[0026] A second parameter acquisition module is configured to re-establish the discrete element rock mass model, and to obtain micro parameters of the granular rock mass based on the macroscopic physical parameters of the rock mass through the indoor test;

[0027] An experiment module is configured to select a typical section representing a surrounding rock grade based on a stress-strain curve of the second parameter acquisition module, to obtain joint occurrence information of the typical section, to perform a blasting test according to a blasting scheme, and to determine overbreak and underbreak values Z obs at different positions of the tunnel by using a laser scanner;

[0028] An inversion calculation module is configured to re-establish a rock mass model, and to perform inversion calculation based on the joint occurrence information and the blasting scheme information obtained by the experiment module;

[0029] A judgment module is configured to compare the overbreak and underbreak values Z obs at different positions of the tunnel after the actual blasting with the results of the inversion calculation, and to determine whether to output or perform a next step;

[0030] An iterative update module is configured to use a gradient descent method to minimize an objective function, and to use an iterative formula to iteratively update the peak value of the blasting load B in the numerical simulation;

[0031] An output module is configured to use the updated parameter B to run the simulation, to calculate a new error after each iteration, and to output the blasting load curve until the calculated error is within an acceptable range;

[0032] The control system is based on the discrete element method-based inversion method for the blasting load curve in the tunnel drilling and blasting construction.

[0033] A third object of the present application is to provide a non-transitory computer readable storage medium storing computer instructions, wherein the computer instructions are configured to cause the computer to perform the discrete element method-based inversion method for the blasting load curve in the tunnel drilling and blasting construction.

[0034] A fourth object of the present application is to provide an electronic device, comprising: at least one processor, and a memory connected in communication with the at least one processor; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to perform an inversion method of a blasting load curve of a tunnel drill-and-blast method construction based on a discrete element method.

[0035] The present application has the beneficial effects that: the present application discloses an inversion method of a blasting load curve of a tunnel drill-and-blast method construction based on a discrete element method, and compared with the prior art, the improvement of the present application is that:

[0036] The present application can accurately invert the best blasting load parameters from the actual blasting results by combining high-precision rock mechanics models and advanced optimization algorithms; the method of the present application first obtains the blasting effects under different load conditions by using discrete element simulation, and then adjusts the load parameters by using an optimization algorithm until the error between the simulation results and the actual blasting results is minimized; in addition, the inversion method of the present application considers common uncertainty factors in actual engineering, such as rock heterogeneity, porosity distribution, etc., and by simulating and analyzing these factors, the reliability and applicability in tunnel blasting numerical simulation are further improved, and the method has good application prospects. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 A flow step diagram of the inversion method of a blasting load curve of a tunnel drill-and-blast method construction based on a discrete element method of the present application;

[0038] Figure 2 A flowchart of the inversion method of a blasting load curve of a tunnel drill-and-blast method construction based on a discrete element method of the present application;

[0039] Figure 3 A comparison diagram of stress-strain curves of triaxial compression tests and numerical simulations of the present application;

[0040] Figure 4 A model joint loading schematic diagram of the present application;

[0041] Figure 5 A model blast hole loading schematic diagram of the present application;

[0042] Figure 6 A comparison diagram of overbreak and underbreak after actual blasting and simulated blasting of the present application;

[0043] Figure 7 A blasting load curve schematic diagram of the present application; DETAILED DESCRIPTION

[0044] In order for those skilled in the art to better understand the technical solutions of the present application, the technical solutions of the present application are further described below in combination with the drawings and examples.

[0045] Embodiments

[0046] Referring to the drawings Figures 1-7 The inversion method for the blasting load curve of the tunnel drill-and-blast method construction based on the discrete element method shown in the drawings includes the following steps:

[0047] S1. Establish a discrete element rock mass model of appropriate size according to the size of the tunnel and the rock mass, and determine the macroscopic physical parameters of the rock through indoor tests;

[0048] Specifically, a discrete element rock mass model of appropriate size is established using a discrete element numerical simulation software according to the size of the construction tunnel and the rock mass, the length of the discrete element rock mass model should be greater than 2 times the excavation footage, the height should be greater than 2 times the diameter, and the width should be greater than 3 times the diameter; the triaxial compression test is used for the indoor test, the test size is 50mm in diameter and 100mm in height, the confining pressure is 10Mpa, complete data is recorded during the test, and the macroscopic physical parameters of the rock are determined, including the stress-strain curve, the failure mode, the elastic model, and the compressive strength;

[0049] S2. Re-establish the discrete element rock mass model, and perform indoor tests based on the macroscopic physical parameters of the rock to obtain the micro parameters of the granular rock mass;

[0050] Specifically, the same model as the indoor test is established in the discrete element numerical simulation software and loaded according to the same load, based on the loaded model, the micro parameters in the model are modified, the macroscopic physical parameters of the model are finally made the same as the macroscopic physical parameters of the indoor test in step S1, so as to ensure the accuracy of the micro parameters and the accuracy of the model; wherein the stress-strain curve is finally obtained by continuously modifying and fitting the micro parameters of the model, and the micro parameters of the granular rock mass are obtained based on the curve; as shown in Figure 3 Table 1 is a comparison of the macroscopic parameters obtained from the simulation according to the input calibrated micro parameters and the parameters of the actual physical test, and Table 2 is the calibrated micro parameters input by the numerical simulation;

[0051] Table 1 Error analysis table of triaxial compression test and numerical simulation

[0052]

[0053] Table 2 Numerical simulation input calibrated micro parameters

[0054]

[0055] S3. Based on the stress-strain curve in step S2, a typical section representing the surrounding rock grade is selected at the construction site, and then the joint occurrence information of the typical section is obtained, and a blasting test (single tunnel blasting excavation) is carried out according to the blasting scheme to obtain the blasting scheme information. After the blasting test, the overbreak value Z is determined at different positions of the tunnel by using a laser scanner obs .

[0056] Specifically, in this step, there are two joints in the typical section rock mass, and there are 95 blasting holes in the blasting scheme, including 37 peripheral holes, 33 auxiliary holes, 12 slotting holes, and 13 floor holes. In the experiment (numerical simulation), the positions of the joints and the blast holes should also be loaded into the model, as shown in Figure 4 、 Figure 5 After the blasting test, the overbreak value Z obs ;

[0057] S4. A new rock mass model is established, and based on the model, inverse calculation is carried out according to the joint occurrence information and the blasting scheme information obtained in step S3;

[0058] A rock mass model is established using discrete element numerical simulation software, which is the same as the model in step S1. Based on the new model, the joint occurrence information obtained from the geological sketch and the information of the blast hole positions and charge amounts of the blasting scheme are used to load the joints and explosives and perform inverse calculation. The overbreak value S sim is measured in the software for different positions in the numerical simulation; wherein the numerical simulation is the same blasting simulation as the rock mass model and the blasting test;

[0059] S5. Based on the overbreak value Z obs , the actual blasting result is compared with the result of the inverse calculation to determine whether to output or proceed to the next step;

[0060] Specifically, the sum of squares of errors at the same position is calculated, and whether the error is within the acceptable range is determined according to the comparison result. If it is within the range, it proves that the inverse calculation is accurately completed, and if it is not within the range, the blasting load curve is output to continue the following steps;

[0061] The formula for calculating the sum of squares of errors at the same position is:

[0062]

[0063] Where Obj(B) is the sum of squares of errors between the numerical simulation value and the actual value, Z obs,i is the actual overbreak value at the i-th point, and S sim,i is the numerical simulation overbreak value at the i-th point; wherein when the sum of squares of errors is within 5% to 10%, it is within the acceptable range, otherwise it is within the unacceptable range;

[0064] S6. The gradient descent method is used to achieve the minimization of the objective function (blasting load), that is, to find the optimal solution of the objective function (blasting load), and the iterative formula is used to iteratively update the blasting load peak value B in the numerical simulation:

[0065] The expression of formula (1) is:

[0066]

[0067] Wherein, α is the calculation step, is the gradient of the objective function B; α is the calculation step, B NEW is the updated blasting load peak value B;

[0068] Further, The sensitivity of the objective function to the parameter change is represented, and the calculation formula is:

[0069]

[0070] Wherein, b k is the kth element in the parameter B, is the partial derivative symbol, B is the blasting load peak value, e k is the standard basis vector, and ∈ is a number that tends to 0 infinitely;

[0071] Wherein, after each iteration, the updated blasting load peak value B is used to run the simulation, and the new error is calculated until the calculated error is within an acceptable range, and the blasting load curve is output;

[0072] After each iteration, the updated parameter B is used to run the simulation, the new error is calculated, the final error is checked whether it is within an acceptable range, and the blasting load peak value B is evaluated for physical reasonableness and practical application feasibility, if the error is within an acceptable range, the process is ended, and if the error is outside the acceptable range, the process returns to step S4.

[0073] The basic principles, main features and advantages of the present application are shown and described above. Those skilled in the art should understand that the present application is not limited by the above examples, and the above examples and descriptions in the specification are only to illustrate the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application. The scope of protection of the present application is defined by the appended claims and their equivalents.

Claims

1. The inversion method of blasting load curve for tunnel drilling and blasting construction based on discrete element method is characterized by: S1. Establish a discrete element rock model of appropriate size based on the tunnel and rock mass dimensions, and conduct indoor tests to determine the macroscopic physical parameters of the rock; S2. Re-establish the discrete element rock mass model and conduct indoor tests based on the macroscopic physical parameters of the rock to obtain the microscopic parameters of the granular rock mass. Among them, the microscopic parameters of granular rock mass are obtained based on stress-strain curve diagram; S3. Based on the stress-strain curve diagram of step S2, a typical section representing the surrounding rock grade is selected to obtain the joint occurrence information of the typical section on site. A blasting test is performed according to the blasting plan to obtain the blasting plan information. The over-excavation value Z at different locations of the tunnel is determined using a laser scanner. obs ; S4. Create a new discrete element rock mass model and perform inversion calculation based on the model according to the joint occurrence information and the blasting plan information obtained in step S3; S5. Based on the over-excavation value Z obs The actual blasting results are compared with the inversion calculation results to determine whether to output or proceed to the next step; S6. Use the gradient descent method to minimize the objective function and use the iterative formula to iteratively update the blasting load peak value B in the numerical simulation; After each iteration, the simulation is run using the updated blasting load peak value B, and the new error is calculated until the calculated error is within an acceptable range, and the blasting load curve is output.

2. The inversion method for blasting load curve of tunnel drilling and blasting construction based on discrete element method according to claim 1 is characterized by: In step S4, the comparison between the actual blasting and the inversion calculation is based on the calculation of the sum of squared errors at the same location. The calculation formula for the sum of squared errors at the same location is: Where Obj(B) is the sum of squares of the errors between the numerical simulation value and the actual value, Z obs,i is the actual over-excavation and under-excavation value of point i, S sim,i is the numerical simulation over-excavation and under-excavation value of point i.

3. The inversion method for blasting load curve of tunnel drilling and blasting construction based on discrete element method according to claim 1 is characterized by: In step S6, the iterative formula is expressed as: Among them, α is the step size, is the gradient of the objective function B; α is the calculation step size, B NEW is the updated blasting load peak value B.

4. The inversion method for blasting load curve of tunnel drilling and blasting construction based on discrete element method according to claim 3 is characterized by: The calculation formula is: Among them, b k is the kth element in parameter B, To find the sign of the partial derivative, B is the peak value of the blasting load, e k is the standard basis vector, and ∈ is a number infinitely close to 0.

5. An inversion system for blasting load curve of tunnel drilling and blasting construction based on discrete element method, characterized in that: The system is implemented based on the method according to any one of claims 1 to 4, including: Parameter acquisition module 1 is used to establish a discrete element rock model of appropriate size according to the tunnel and rock mass dimensions, and conduct indoor tests to determine the macroscopic physical parameters of the rock; Parameter acquisition module 2 is used to re-establish the discrete element rock mass model and conduct indoor experiments based on the macroscopic physical parameters of the rock to obtain the microscopic parameters of the granular rock mass; The experimental module is used to select a typical section representing the surrounding rock grade based on the stress-strain curve diagram of the parameter acquisition module 2, and then obtain the joint occurrence information of the typical section, and conduct blasting tests according to the blasting plan, and use a laser scanner to determine the over-excavation value Z at different locations of the tunnel. obs ; The inversion calculation module is used to create a new rock mass model and perform inversion calculation based on the model according to the joint occurrence information and the blasting plan information obtained from the experimental module; Judgment module, used to determine the value of over-excavation and under-excavation based on Z obs The actual blasting results are compared with the inversion calculation results to determine whether to output or proceed to the next step; The iterative update module uses the gradient descent method to minimize the objective function and uses the iterative formula to iteratively update the blasting load peak value B in the numerical simulation; In the output module, after each iteration, the simulation is run using the updated parameter B, the new error is calculated, and the blasting load curve is output until the calculated error is within an acceptable range.

6. A non-transitory computer-readable storage medium storing computer instructions, wherein: The computer instructions are used to cause the computer to execute the method according to any one of claims 1-4.

7. An electronic device comprising: At least one processor, and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to perform the method according to any one of claims 1 to 4.

Images