Blasting damage simulation technology adaptive to on-site rock mass

Abstract

The invention provides a blasting damage simulation technology adaptive to an on-site rock mass. The blasting damage simulation technology comprises the following steps: establishing a function relationship among a rock mass blasting damage variable, a rock mass sound wave velocity and a rock mass mechanical parameter; continuously carrying out a rock mass acoustic wave test, and establishing a blasting damage constitutive relation adaptive to a field rock mass; introducing the rock mass blasting damage constitutive relation of the rock mass damage calculation input parameters embedded with the damage variables and the embedding time into blasting damage numerical simulation to obtain a blasting damage model; and compiling the blasting damage model into a user-defined program in a user fixed format by adopting a Fortran language, embedding the user-defined program into dynamic finite element software LSDYNA through a secondary development interface, and calculating and simulating rock blasting damage characteristics. On the basis of the method, the blasting damage characteristics of the on-site rock mass can be accurately predicted.

Description

Technical Field

[0001] The invention belongs to the technical field of geotechnical engineering, and in particular relates to a blasting damage simulation technology that is adaptive to on-site rock masses. Background Art

[0002] During the rock blasting excavation process, the blasting load will inevitably cause a certain degree of damage to the retained rock mass near the excavation surface, affecting the stability of the project. The use of acoustic wave testing to determine the range of rock damage is time-consuming, labor-intensive and highly subjective. Accurately and quickly predicting the range of rock blasting damage, and thus proposing effective control measures, is of great significance for ensuring the safety of blasting construction. To this end, relevant scholars have carried out a large number of studies, proposed a series of rock blasting damage models, and estimated the rock blasting damage characteristics through numerical simulation methods. Since these models are proposed for different rock masses, although they have been applied to a certain extent in related research, the determination of rock mass parameters is complex and does not have the requirements for flexible adjustment. The applicability and accuracy in specific actual projects still need to be discussed and verified. Therefore, it is necessary to propose a blasting damage numerical simulation technology that is adaptive to the on-site rock mass, so as to achieve effective control of rock excavation blasting damage and ensure the long-term operation safety of rock high slope excavation blasting. Summary of the invention

[0003] In view of the problems existing in the prior art, the present invention intends to provide a blasting damage simulation technology that is adaptive to the on-site rock mass and can accurately predict the blasting damage characteristics of the on-site rock mass. The technical solutions adopted by the present invention to solve the problems existing in the prior art are as follows:

[0004] A blasting damage simulation technology adaptive to on-site rock mass includes the following steps:

[0005] Step 1: Establish the functional relationship between rock blasting damage variables and rock acoustic wave velocity and rock mechanical parameters, and use a combination of elastic mechanics theoretical calculation method and mathematical fitting method to establish the iterative relationship between the physical and mechanical parameters required to be input in blasting damage calculation and the damage variables;

[0006] Step 2: Continue to carry out rock mass acoustic wave testing, track the changing characteristics of rock mass damage development and physical and mechanical parameter changes, use regression analysis to establish the mechanical relationship between damage and time development, and based on 8 to 10 data fittings, take the average value of each fitting to establish a blasting damage constitutive relationship suitable for the on-site rock mass;

[0007] Step 3: Based on the analysis results of step 1 and step 2, the rock damage calculation input parameters embedded with damage variables and the rock blasting damage constitutive relation embedded with time are respectively introduced into the blasting damage numerical simulation to obtain the blasting damage model, so as to realize the learning and adaptation of blasting damage calculation and rock dynamic characteristics;

[0008] Step 4: Use Fortran language to compile the blasting damage model into a user-defined program in a fixed format, and embed the user-defined program into the dynamic finite element software LSDYNA through the secondary development interface to calculate and simulate the rock blasting damage characteristics.

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

[0010]

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

[0012] The functional relationship between the rock mass blasting damage variable and the rock mass mechanical parameters in step 1 is established based on the generalized Hoek Brown criterion as follows:

[0013]

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

[0015]

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

[0017] According to equations (1)-(5), a functional relationship between the rock mass blasting damage variable and the rock mass acoustic wave velocity and rock mass mechanical parameters is established.

[0018] The step 2 specifically includes:

[0019] Step 2.1, arranging 2 to 4 groups of sonic wave test holes in the on-site blasting area, testing the sonic wave velocity of the rock mass at different depths in each group of sonic wave test holes, obtaining the sonic wave velocity of the rock mass at different depths in each group of sonic wave test holes, and determining the sonic wave velocity of the undamaged rock mass based on the principle that the sonic wave velocity of the damaged rock mass is lower than the sonic wave velocity of the undamaged rock mass;

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

[0021] Step 2.3, the measured rock mass acoustic wave velocities at the same depth in multiple groups of acoustic wave test holes are accumulated and averaged, the calculated rock mass blasting damage variables at the same depth in multiple groups of acoustic wave test holes are accumulated and averaged, the average values ​​of rock mass acoustic wave velocities at different depths in the acoustic wave test holes are fitted with the average values ​​of rock mass blasting damage variables, and the optimized functional relationship between rock mass blasting damage variables and rock mass acoustic wave velocities is obtained:

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

[0023] Step 2.4: Based on the measured rock mass acoustic wave velocity at different depths in each group of acoustic wave test holes and the determined undamaged rock mass acoustic wave velocity, the optimized rock mass blasting damage variables at different depths in each group of acoustic wave test holes are calculated based on formula (6), and the rock mass material parameters m at different depths in each group of acoustic wave test holes are further calculated based on formulas (3)-(4). b with s;

[0024] Step 2.5: calculate the rock material parameters m at the same depth in multiple groups of acoustic wave test holes b , s are accumulated and their respective average values ​​are taken. The optimized rock blasting damage variables at the same depth in multiple groups of acoustic wave test holes are accumulated and averaged. The rock material parameters m at different depths in the acoustic wave test hole are calculated. b The average values ​​of s and optimized rock blasting damage variables are fitted to obtain the rock blasting damage variables and rock material parameters m b , the optimization function relationship of s:

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

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

[0027] Step 2.6: Carry out blasting sonic wave tests for 8 to 10 steps continuously to track the changing characteristics of rock damage development. Use regression analysis to establish the mechanical relationship between damage development over time. Based on data fitting, take the average value of each fitting to establish a blasting damage constitutive relationship suitable for the on-site rock mass.

[0028] D=f(t,σ1,σ3,σ c ,m i ,GSI) (9)

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

[0030]

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

[0032] I1=σ x +σ y +σ z (11)

[0033]

[0034]

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

[0036] Arranging the three real roots of formula (10) according to the size of the algebraic value, the maximum principal stress σ1 and the minimum principal stress σ3 of the rock mass unit are obtained, which are 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 equations (9), (14) and (15), the rock mass blasting damage variable D is calculated and corrected. If D ≥ 1, D = 1 and the failure criterion is added to set the unit to fail.

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

[0041]

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

[0043]

[0044] The damage effect of rock under blasting load is recorded according to the incremental Hooke's law:

[0045]

[0046] Before establishing a blasting damage model that is adaptive to the on-site rock mass, it also includes: determining the uniaxial compressive strength σ of the intact rock based on engineering geological surveys and indoor tests of rock physical and mechanical parameters c 、The hardness parameter of rock m i and the geological strength index GSI of the rock mass.

[0047] The present invention has the following advantages:

[0048] (1) A blasting damage simulation technology that is adaptive to the rock mass damage variables and the rock mass physical and mechanical calculation parameters is established. This technology can accurately and dynamically reflect the changing characteristics of the rock mass input physical and mechanical parameters under the action of blasting damage.

[0049] (2) A method for adaptively calculating the time-varying damage constitutive relation of the rock mass is established, which breaks through the technical bottleneck of assuming elasticity or ideal elastoplasticity in traditional numerical calculations. Through self-adaptation and self-learning, the blasting damage characteristics of the rock mass on site can be accurately predicted, providing better guidance for the actual engineering safety design.

[0050] (3) The present invention dynamically integrates the field test results into the blasting damage simulation calculation, achieving technical progress in numerical simulation calculation parameter verification and field comparison correction. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 It is a schematic diagram of the blasting damage simulation process of the present invention which is adaptive to the on-site rock mass;

[0052] Figure 2 A schematic diagram of the rock mass acoustic wave test arrangement required for the adaptive simulation method of the present invention;

[0053] Figure 3 It is a schematic diagram of the adaptive constitutive relationship of rock mass according to the present invention. DETAILED DESCRIPTION

[0054] The technical solution of the present invention is further specifically described below through embodiments and in conjunction with the accompanying drawings.

[0055] Embodiment 1:

[0056] Taking a certain project as an example, in order to calculate the distribution range of blasting damage in the rock mass, 10 steps were selected with a step height of 10m. The rock mass lithology is basalt. For the 10 steps, the rock mass acoustic wave test was carried out from top to bottom. The acoustic wave test schematic diagram is shown as follows: Figure 2 As shown in FIG. 1 , the rock mass acoustic wave is tested before and after the blast, and the rock mass acoustic wave reduction rate before and after each blast is calculated. The technical solution of the present invention is used to perform blasting damage simulation that is adaptive to the on-site rock mass, such as Figure 1 As shown, the following steps are included:

[0057] Step 1: Establish the functional relationship between rock blasting damage variables and rock acoustic wave velocity and rock mechanical parameters.

[0058] Step 2: Continue to carry out rock mass acoustic wave testing, track the changing characteristics of rock mass damage development and physical and mechanical parameters, use regression analysis to establish the mechanical relationship between damage and time development, and based on 8 to 10 data fittings, take the average value of each fitting to establish a blasting damage constitutive relationship suitable for the on-site rock mass, such as Figure 3 shown.

[0059] Step 3: The rock damage calculation parameters embedded with the damage variables are used as input parameters, and the mathematical equation of the rock blasting damage variation curve embedded with time is used as the constitutive relationship.

[0060] Step 4: Use Fortran language to compile the blasting damage model into a user-defined program in a fixed format, and embed the user-defined program into the dynamic finite element software LSDYNA through the secondary development interface to calculate and simulate the rock blasting damage characteristics.

[0061] The protection scope of the present invention is not limited to the above-mentioned embodiments. Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the scope and spirit of the present invention. If these changes and modifications fall within the scope of the claims of the present invention and their equivalents, the present invention is intended to include these changes and modifications.

Claims

1. A blasting damage simulation technology that is adaptive to the on-site rock mass, characterized in that: The steps include: Step 1: Establish the functional relationship between rock blasting damage variables and rock acoustic wave velocity and rock mechanical parameters, and use a combination of elastic mechanics theoretical calculation method and mathematical fitting method to establish the iterative relationship between the physical and mechanical parameters required to be input in blasting damage calculation and the damage variables; Step 2: Continue to carry out rock mass acoustic wave testing, track the changing characteristics of rock mass damage development and physical and mechanical parameter changes, use regression analysis to establish the mechanical relationship between damage and time development, and based on 8 to 10 data fittings, take the average value of each fitting to establish a blasting damage constitutive relationship suitable for the on-site rock mass; Step 3: Based on step 1 and step 2, the rock damage calculation input parameters embedded with damage variables and the rock blasting damage constitutive relation embedded with time are respectively introduced into the blasting damage numerical simulation to obtain the blasting damage model, so as to realize the learning and adaptation of blasting damage calculation and rock dynamic characteristics; Step 4: Use Fortran language to compile the blasting damage model into a user-defined program in a fixed format, and embed the user-defined program into the dynamic finite element software LSDYNA through the secondary development interface to calculate and simulate the rock blasting damage characteristics.

2. The blasting damage simulation technology adaptive to the on-site rock mass according to claim 1, characterized in that: The functional relationship expression established between the rock mass blasting damage variable and the rock mass acoustic wave velocity in step 1 is as follows: In formula (1): D is the rock mass blasting damage variable; v P is the measured rock mass acoustic wave velocity; v P0 is the acoustic wave velocity of undamaged rock mass; The functional relationship between the rock mass blasting damage variable and the rock mass mechanical parameters in step 1 is established based on the generalized Hoek Brown criterion as follows: In formula (2), σ1 and σ3 are the maximum and minimum principal stresses of the rock mass, respectively; σ c is the uniaxial compressive strength of intact rock; m b , s, a are rock material parameters, which are related to the lithology and rock structure surface conditions and can be expressed as: In formulas (3)-(5), GSI is the geological strength index; D is the rock mass blasting damage variable, which represents the weakening of rock mass mechanical parameters caused by blasting excavation; m i It is a parameter reflecting the hardness of intact rock; According to equations (1)-(5), a functional relationship between the rock mass blasting damage variable and the rock mass acoustic wave velocity and rock mass mechanical parameters is established.

3. The blasting damage simulation technology adaptive to the on-site rock mass according to claim 2, characterized in that: The step 2 specifically includes: Step 2.1, arranging 2 to 4 groups of sonic wave test holes in the on-site blasting area, testing the sonic wave velocity of the rock mass at different depths in each group of sonic wave test holes, obtaining the sonic wave velocity of the rock mass at different depths in each group of sonic wave test holes, and determining the sonic wave velocity of the undamaged rock mass based on the principle that the sonic wave velocity of the damaged rock mass is lower than the sonic wave velocity of the undamaged rock mass; Step 2.2, according to the measured rock mass acoustic wave velocity at different depths in each group of acoustic wave test holes and the determined undamaged rock mass acoustic wave velocity, the rock mass blasting damage variable at different depths in each group of acoustic wave test holes is calculated based on formula (1); Step 2.3, the measured rock mass acoustic wave velocities at the same depth in multiple groups of acoustic wave test holes are accumulated and averaged, the calculated rock mass blasting damage variables at the same depth in multiple groups of acoustic wave test holes are accumulated and averaged, the average values ​​of rock mass acoustic wave velocities at different depths in the acoustic wave test holes are fitted with the average values ​​of rock mass blasting damage variables, and the optimized functional relationship between rock mass blasting damage variables and rock mass acoustic wave velocities is obtained: D=f1(v p ) (6) Step 2.4: Based on the measured rock mass acoustic wave velocity at different depths in each group of acoustic wave test holes and the determined undamaged rock mass acoustic wave velocity, the optimized rock mass blasting damage variables at different depths in each group of acoustic wave test holes are calculated based on formula (6), and the rock mass material parameters m at different depths in each group of acoustic wave test holes are further calculated based on formulas (3)-(4). b with s; Step 2.5: calculate the rock material parameters m at the same depth in multiple groups of acoustic wave test holes b , s are accumulated and their respective average values ​​are taken. The optimized rock blasting damage variables at the same depth in multiple groups of acoustic wave test holes are accumulated and averaged. The rock material parameters m at different depths in the acoustic wave test hole are calculated. b The average values ​​of s and optimized rock blasting damage variables are fitted to obtain the rock blasting damage variables and rock material parameters m b , the optimization function relationship of s: m b =f2(D) (7) s=f3(D) (8) Step 2.6, continuously carry out 8 to 10 steps of blasting sonic wave tests, track the changing characteristics of rock damage development, use regression analysis to establish the mechanical relationship of damage development over time, and based on data fitting, take the average value of each fitting to establish a blasting damage constitutive relationship suitable for the on-site rock mass; D=f(t,σ1,σ3,σ c ,m i (9).

4. The blasting damage simulation technology adaptive to the on-site rock mass according to claim 1, characterized in that: The step 3 specifically includes: calculating the principal stress of the rock mass unit according to the characteristic equation of stress state: In formula (10): n represents the principal stress of the rock mass unit, I1, I2, and I3 are the first, second, and third stress tensor invariants, respectively, which can be expressed as: I1=σ x +s y +s z (11) In formulas (11)-(13): x , σ y , σ z , τ xy , τ yz , τ zx are six independent stress components of the rock mass unit; Arranging the three real roots of formula (10) according to the size of the algebraic value, the maximum principal stress σ1 and the minimum principal stress σ3 of the rock mass unit are obtained, which are expressed as: σ1=g1(σ1,σ2,σ3,τ xy ,t yz ,t zx ) (14) σ3=g2(σ1,σ2,σ3,τ xy ,t yz ,t zx ) (15) According to equations (9), (14) and (15), the rock mass blasting damage variable D is calculated and corrected. If D ≥ 1, D = 1 and the failure criterion is added to set the unit to fail. 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:

5. The blasting damage simulation technology adaptive to the on-site rock mass according to claim 1, characterized in that: Before establishing a blasting damage model that is adaptive to the on-site rock mass, it also includes: determining the uniaxial compressive strength σ of the intact rock based on engineering geological surveys and indoor tests of rock physical and mechanical parameters c 、The hardness parameter of rock m i and the geological strength index GSI of the rock mass.

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