A blasting damage simulation technique adaptive to in-situ rock mass

Abstract

The application provides a kind of blasting damage simulation technology that is self-adaptive to field rock mass, comprising the following steps: establishing the functional relationship between rock mass blasting damage variable and rock mass acoustic velocity and rock mass mechanical parameter; continuously carrying out rock mass acoustic wave test, and establishing blasting damage constitutive relation adaptive to field rock mass; respectively introducing rock mass damage calculation input parameter embedded with damage variable and rock mass blasting damage constitutive relation embedded with time into blasting damage numerical simulation to obtain blasting damage model; using Fortran language to compile the user fixed format self-defined program of blasting damage model, embedding the user self-defined program into dynamic finite element software LSDYNA through secondary development interface to calculate and simulate rock mass blasting damage characteristics. The method of the application can accurately predict the blasting damage characteristics of field rock mass.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of geotechnical engineering, and particularly relates to a blasting damage simulation technology self-adapting to in-situ rock mass. BACKGROUND

[0002] During the process of rock mass blasting excavation, blasting load will inevitably cause a certain degree of damage to the retained rock mass near the excavation surface, affecting the engineering stability. It is time-consuming and laborious to determine the rock mass damage range by using the acoustic testing method, and it is highly subjective. Therefore, it is of great significance to ensure the safety of blasting construction to accurately and quickly predict the rock mass blasting damage range and propose effective control measures. For this reason, relevant scholars have carried out a large number of researches and proposed a series of rock mass blasting damage models, and the numerical simulation method is used to predict the blasting damage characteristics of rock mass. Since these models are proposed for different rock masses, although they have been applied in related researches, the determination of rock mass parameters is complex, and they do not have the requirement of flexible adjustment, so the applicability and accuracy in specific actual engineering still need to be discussed and verified. Therefore, it is necessary to propose a blasting damage numerical simulation technology self-adapting to in-situ rock mass, so as to realize the effective control of rock mass excavation blasting damage and ensure the long-term operation safety of rock high slope excavation blasting. SUMMARY

[0003] In view of the problems existing in the prior art, the present application provides a blasting damage simulation technology self-adapting to in-situ rock mass, which can accurately predict the blasting damage characteristics of in-situ rock mass. The technical solutions adopted by the present application to solve the problems existing in the prior art are as follows:

[0004] A blasting damage simulation technology self-adapting to in-situ rock mass comprises the following steps:

[0005] Step 1: Establishing a functional relationship between the rock mass blasting damage variable and the rock mass acoustic velocity and the rock mass mechanical parameter, using the method of combining the elastic mechanics theory calculation method and mathematical fitting to establish the iterative relationship between the physical and mechanical parameters required to be input in the blasting damage calculation and the damage variable;

[0006] Step 2: Continuously carrying out rock mass acoustic testing, tracking the change characteristics of rock mass damage development and the change characteristics of physical and mechanical parameters, using the method of regression analysis to establish the mechanical relationship of damage development with time, based on the fitting of 8-10 times of data, taking the average value of each fitting, and establishing the blasting damage constitutive relationship self-adapting to in-situ rock mass;

[0007] Step 3: Based on the analysis results of step 1 and step 2, respectively introducing the rock mass damage calculation input parameters embedded with the damage variable and the rock mass blasting damage constitutive relationship embedded with time into the blasting damage numerical simulation to obtain the blasting damage model, realizing the learning and adaptation of the blasting damage calculation and the dynamic characteristics of rock mass;

[0008] Step 4, the blasting damage model is compiled into a user fixed format self-defined program by using Fortran language, the user self-defined program is embedded into the dynamic finite element software LSDYNA through a secondary development interface, and the blasting damage characteristics of the rock mass are calculated and simulated.

[0009] The function relationship expression between the blasting damage variable of the rock mass in the step 1 and the acoustic wave velocity of the rock mass is as follows:

[0010]

[0011] In formula (1), D is the blasting damage variable of the rock mass; v P is the measured acoustic wave velocity of the rock mass; v P0 is the acoustic wave velocity of the undamaged rock mass;

[0012] The function relationship expression between the blasting damage variable of the rock mass in the step 1 and the mechanical parameter of the rock mass, based on the generalized Hoek Brown criterion, is as follows:

[0013]

[0014] In formula (2), σ1 and σ3 are the maximum principal stress and the minimum principal stress of the rock mass respectively; σ c is the uniaxial compressive strength of the intact rock; m b s, a are rock mass material parameters, which are related to the lithology and the structure surface of the rock mass, and can be respectively expressed as:

[0015]

[0016] In formula (3)-(5), GSI is the geological strength index; D is the blasting damage variable of the rock mass, which represents the weakening of the mechanical parameter of the rock mass caused by blasting excavation; m i is a parameter reflecting the softness and hardness of the intact rock;

[0017] According to formula (1)-(5), the function relationship between the blasting damage variable of the rock mass and the acoustic wave velocity of the rock mass and the mechanical parameter of the rock mass is established.

[0018] The step 2 specifically comprises:

[0019] Step 2.1, 2-4 groups of acoustic wave test holes are arranged in the field blasting area, the acoustic wave velocity of the rock mass at different depths in each group of acoustic wave test holes is tested, the acoustic wave velocity of the rock mass at different depths in each group of acoustic wave test holes is obtained, and the acoustic wave velocity of the undamaged rock mass is determined according to the principle that the damaged rock mass acoustic wave velocity is lower than the undamaged rock mass acoustic wave velocity;

[0020] Step 2.2, based on formula (1), calculate the blasting damage variable of rock mass at different depths in each group of acoustic test holes according to the measured acoustic wave velocity of rock mass at different depths in each group of acoustic test holes and the determined acoustic wave velocity of undamaged rock mass;

[0021] Step 2.3, accumulate and take the average value of the measured acoustic wave velocity of rock mass at the same depth in multiple groups of acoustic test holes, accumulate and take the average value of the calculated blasting damage variable of rock mass at the same depth in multiple groups of acoustic test holes, and fit the average value of the acoustic wave velocity of rock mass at different depths in the acoustic test hole and the average value of the blasting damage variable of rock mass to obtain the optimized function relationship between the blasting damage variable of rock mass and the acoustic wave velocity of rock mass:

[0022] D = f1(v p ) (6)

[0023] Step 2.4, based on formula (6), calculate the optimized blasting damage variable of rock mass at different depths in each group of acoustic test holes according to the measured acoustic wave velocity of rock mass at different depths in each group of acoustic test holes and the determined acoustic wave velocity of undamaged rock mass, and further based on formula (3)-(4), calculate the rock mass material parameters m b and s at different depths in each group of acoustic test holes.

[0024] Step 2.5, respectively accumulate and take the average value of the calculated rock mass material parameters m b and s at the same depth in multiple groups of acoustic test holes, accumulate and take the average value of the calculated optimized blasting damage variable of rock mass at the same depth in multiple groups of acoustic test holes, and respectively fit the average value of the rock mass material parameters m b and s at different depths in the acoustic test hole and the average value of the optimized blasting damage variable of rock mass to obtain the optimized function relationship between the blasting damage variable of rock mass and the rock mass material parameters m b and s:

[0025] m b = f2(D) (7)

[0026] s = f3(D) (8)

[0027] Step 2.6, continuously carry out blasting acoustic tests of 8-10 steps, track the change characteristics of the development of rock mass damage, use the method of regression analysis to establish the mechanical relationship of damage with time, based on data fitting, take the average value of each fitting, and establish the blasting damage constitutive relationship suitable for the site rock mass.

[0028] D = f(t,σ1,σ3,σ c ,m i ,GSI) (9)

[0029] The step 3 specifically comprises: calculating the principal stress of the rock mass unit according to the stress state characteristic equation:

[0030]

[0031] In formula (10): σ n represents the principal stress of the rock mass unit, I1, I2, I3 are the first, second, and third stress tensor invariants, which can be expressed as:

[0032] I1=σ x +σ y +σ z (11)

[0033]

[0034]

[0035] In formulas (11)-(13): σ x , σ y , σ z , τ xy , τ yz , τ zx are six independent stress components of the rock mass unit;

[0036] Arrange the three real roots of formula (10) according to the algebraic value, and obtain the maximum principal stress σ1 and the minimum principal stress σ3 of the rock mass unit, which are respectively expressed as:

[0037] σ1=g1(σ1,σ2,σ3,τ xy ,τ yz ,τ zx ) (14)

[0038] σ3=g2(σ1,σ2,σ3,τ xy ,τ yz ,τ zx ) (15)

[0039] According to formulas (9), (14), and (15), calculate the rock mass blasting damage variable D and correct it, if D≥1, then D=1 and add the failure criterion to set the unit failure;

[0040] Based on the generalized Hoek Brown criterion, the elastic modulus E of the rock mass is calculated as: The calculation formula is:

[0041]

[0042] The Poisson's ratio of the rock mass is calculated as: The calculation formula is:

[0043]

[0044] According to the incremental Hook's law, the damage effect of rock under blasting load is recorded:

[0045]

[0046] Before the establishment of the blasting damage model adaptive to the field rock mass, the following is further included: according to the engineering geological survey and the indoor test of the rock physical and mechanical parameters, the uniaxial compressive strength σ c , the soft and hard degree parameter m i of the rock and the geological strength index GSI of the rock mass are determined.

[0047] The present application has the following advantages:

[0048] (1) A blasting damage simulation technology adaptive to the rock mass damage variable and the rock mass physical and mechanical calculation parameters is established, which can accurately and dynamically reflect the change characteristics of the input physical and mechanical parameters of the rock mass under the blasting damage effect.

[0049] (2) A method for changing the damage constitutive relation adaptive to the rock mass with time is established, which breaks through the technical bottleneck of the traditional numerical calculation using the assumed elasticity or ideal elastoplasticity, and through the self-adaptation and self-learning, the blasting damage characteristics of the field rock mass can be accurately estimated, thereby providing a better guidance for the actual engineering safety design.

[0050] (3) The present application dynamically integrates the field test results into the blasting damage simulation calculation, thereby realizing the technical progress of the numerical simulation calculation parameter checking and the field comparison correction. DETAILED DESCRIPTION

[0051] Figure 1 Fig. 1 is a schematic diagram of the blasting damage simulation process adaptive to the field rock mass of the present application;

[0052] Figure 2 Fig. 2 is a schematic diagram of the rock mass acoustic wave test arrangement required by the adaptive simulation method of the present application;

[0053] Figure 3 Fig. 3 is a schematic diagram of the rock mass adaptive constitutive relation of the present application. DETAILED DESCRIPTION

[0054] The technical solutions of the present application will be further specifically described below by means of embodiments and in combination with the drawings.

[0055] Embodiment 1:

[0056] Taking a certain project as an example, in order to calculate the blasting damage distribution range of the rock mass, 10 steps are selected, the step height is 10 m, the rock mass lithology is basalt, and the rock mass acoustic wave test is carried out from top to bottom for the 10 steps, and the acoustic wave test schematic diagram is as follows:Figure 2 As shown, the rock mass acoustic wave is tested before and after blasting, and the rock mass acoustic wave reduction rate before and after each blasting is calculated. Figure 1 As shown, the method comprises the following steps:

[0057] Step 1, a function relationship between the rock mass blasting damage variable and the rock mass acoustic wave velocity and the rock mass mechanical parameter is established.

[0058] Step 2, the rock mass acoustic wave test is continuously carried out, the change characteristics of the rock mass damage development and the physical and mechanical parameter change characteristics are tracked, the regression analysis method is adopted to establish the mechanical relationship of the damage with time development, based on the fitting of 8-10 data, the average value of each fitting is taken, and the blasting damage constitutive relationship suitable for the on-site rock mass is established, as shown in Figure 3 .

[0059] Step 3, the rock mass damage calculation parameter embedded with the damage variable is taken as an input parameter, and the mathematical equation of the rock mass blasting damage change curve embedded with time is taken as the constitutive relationship.

[0060] Step 4, the Fortran language is adopted to compile the blasting damage model into a user fixed format self-defined program, the user self-defined program is embedded into the dynamic finite element software LSDYNA through a secondary development interface, and the rock mass blasting damage characteristics are calculated and simulated.

[0061] The protection scope of the present application is not limited to the above-mentioned embodiments, and obviously, those skilled in the art can make various modifications and changes to the present application without departing from the scope and spirit of the present application. If these modifications and changes belong to the scope of the claims of the present application and the equivalent technology, the intention of the present application also includes these modifications and changes.

Claims

1. A blasting damage simulation technology that adapts to on-site rock mass, characterized in that, Includes the following steps: Step 1: Establish the functional relationship between rock mass blasting damage variables and rock mass acoustic velocity and rock mass mechanical parameters. Use a combination of elasticity theory calculation method and mathematical fitting method to establish the iterative relationship between the physical and mechanical parameters that need to be input in blasting damage calculation and damage variables. Step 2: Continuously conduct acoustic testing of rock mass to track the changes in the characteristics of rock mass damage development and physical and mechanical parameters. Use regression analysis to establish the mechanical relationship of damage development over time. Based on the fitting of 8 to 10 data points, take the average value of each fitting to establish a blasting damage constitutive relationship adapted to the rock mass in the field. Step 3: Based on Step 1 and Step 2, the rock mass damage calculation input parameters with embedded damage variables and the rock mass blasting damage constitutive relation with embedded time are introduced into the blasting damage numerical simulation to obtain the blasting damage model, thereby realizing the learning and adaptation of blasting damage calculation and rock mass dynamic characteristics. Step 4: Compile the blasting damage model into a user-defined program in a fixed format using Fortran language, and embed the user-defined program into the dynamic finite element software LSDYNA through a secondary development interface to calculate and simulate the blasting damage characteristics of rock mass. The functional relationship between the rock mass blasting damage variable and the rock mass acoustic velocity established in step 1 is expressed as follows: In equation (1): D is the rock mass blasting damage variable; v P The measured acoustic velocity of the rock mass; v P0 The acoustic wave velocity of the undamaged rock mass; The functional relationship between the rock mass blasting damage variables and rock mass mechanical parameters in step 1, based on the generalized Hoek Brown criterion, is as follows: In equation (2): σ1 and σ3 are the maximum principal stress and minimum principal stress of the rock mass, respectively; σ c The uniaxial compressive strength of intact rock; m b s and a are rock mass material parameters, which are related to lithology and rock mass structure, and are expressed as follows: In equations (3)-(5): GSI is the geological strength index; D is the rock mass blasting damage variable, characterizing the weakening of rock mass mechanical parameters caused by blasting excavation; m i A parameter reflecting the hardness or softness of an intact rock; Based on equations (1)-(5), the functional relationship between the rock mass blasting damage variable and the rock mass acoustic velocity and rock mass mechanical parameters is established.

2. The blasting damage simulation technology that adapts to the on-site rock mass as described in claim 1, characterized in that: Step 2 specifically includes: Step 2.1: Arrange 2 to 4 sets of acoustic wave test holes in the blasting area on site, and test the acoustic wave velocity of the rock mass at different depths in each set of acoustic wave test holes to obtain the acoustic wave velocity of the rock mass at different depths in each set of acoustic wave test holes. Based on the principle that the acoustic wave velocity of the damaged rock mass is lower than that of the undamaged rock mass, determine the acoustic wave velocity of the undamaged rock mass. Step 2.2: Based on the measured acoustic velocity of the rock mass at different depths in each set of acoustic test holes and the determined acoustic velocity of the undamaged rock mass, calculate the blasting damage variable of the rock mass at different depths in each set of acoustic test holes based on Equation (1). Step 2.3: Accumulate and average the measured rock mass acoustic velocities at the same depth within multiple sets of acoustic test holes. Accumulate and average the calculated rock mass blasting damage variables at the same depth within multiple sets of acoustic test holes. Fit the average rock mass acoustic velocity at different depths within the acoustic test holes to the average rock mass blasting damage variable to obtain the optimized functional relationship between the rock mass blasting damage variable and the rock mass acoustic velocity: D=f1(v p ) (6) Step 2.4: Based on the measured acoustic velocity of the rock mass at different depths in each set of acoustic test holes and the determined acoustic velocity of the undamaged rock mass, calculate the optimized rock mass blasting damage variable at different depths in each set of acoustic test holes based on equation (6), and further calculate the rock mass material parameter m at different depths in each set of acoustic test holes based on equations (3)-(4). b With s; Step 2.5: Calculate the rock mass material parameters (m) at the same depth within multiple sets of acoustic test holes. b The calculated values ​​of s and s are summed and averaged separately. The optimized rock blasting damage variables at the same depth within multiple sets of acoustic test holes are summed and averaged. The rock material parameters m at different depths within the acoustic test holes are then analyzed. b The average values ​​of s and the optimized average value of the rock mass blasting damage variable are fitted to obtain the relationship between the rock mass blasting damage variable and the rock mass material parameter m. b The optimal functional relationship between and s: m b =f2(D) (7) s=f3(D) (8) Step 2.6: Conduct continuous sonic testing at 8-10 steps to track the changing characteristics of rock mass damage development. Use regression analysis to establish the mechanical relationship of damage development over time. Based on data fitting, take the average value of each fitting to establish a constitutive relationship of blast damage adapted to the rock mass at the site. D=f(t,σ1,σ3,σ c ,m i (9).

3. The blasting damage simulation technology that adapts to the on-site rock mass as described in claim 2, characterized in that: Step 3 specifically includes: calculating the principal stresses of the rock mass elements based on the stress state characteristic equation. In equation (10): σ n Let I1, I2, and I3 represent the principal stresses of the rock mass element, respectively, and let I1, I2, and I3 be the invariants of the first, second, and third stress tensors, respectively. I1=σ x +s y +s z (11) In equations (11)-(13): σ x σ y σ z , The rock mass element consists of six independent stress components. Arranging the three real roots of equation (10) according to their algebraic values, we obtain the maximum principal stress σ1 and the minimum principal stress σ3 of the rock mass element, which are expressed as follows: According to equations (9), (14), and (15), calculate the rock mass blasting damage variable D and correct it. If D ≥ 1, then let D = 1 and add a failure criterion to set the unit failure. Based on the generalized Hoek Brown criterion, the elastic modulus of rock mass The calculation formula is: Poisson's ratio of rock mass The calculation formula is: The damage effect of rock under blasting load is recorded according to the incremental Hooke's law:

4. The blasting damage simulation technology that adapts to the on-site rock mass as described in claim 1, characterized in that: Before establishing a blasting damage model that is adaptive to the on-site rock mass, the following steps are also included: determining the uniaxial compressive strength σ of intact rock based on engineering geological surveys and laboratory tests of rock physical and mechanical parameters. c The rock's hardness parameter m i And the geological strength index (GSI) of the rock mass.

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