Method for evaluating multi-stage blasting disturbance and accumulated damage of high and steep slope

Abstract

The invention discloses a method for evaluating multi-stage blasting disturbance and accumulated damage of a high and steep slope. The method comprises the following steps: step 1, acquiring relevant parameters and blasting parameters of the slope; 2, according to the excavation disturbance factors obtained in the step 1 and the depth of the excavation damage area, a schematic diagram of the range of the excavation damage area under first-level excavation is drawn, and material degradation parameters under the first-level damage area are solved; step 3, performing secondary blasting in a corresponding range, and solving material parameters after secondary blasting excavation; and fourthly, next excavation is conducted till the blasting excavation working condition is completed. Compared with the prior art, the method has the advantages that the rock slope material parameter degradation scale factor under each stage of blasting excavation is added and applied to the working condition of multi-stage slope blasting excavation, and the influence of accumulated damaged rock mass on the slope stability is considered; and the change of the multi-stage blasting excavation safety coefficient of the rock slope is explored while the actual working condition is better met.

Description

Technical Field

[0001] The present invention relates to the technical field of blasting, and specifically refers to a method for evaluating multi-stage blasting disturbance and cumulative damage of high-steep slopes. Background Art

[0002] High-steep slopes are relatively common in high-altitude and high in-situ stress scenarios. With the road reconstruction and expansion or the decreasing service life of mines and hydropower stations, it is necessary to excavate the surrounding slopes to ensure their stability requirements and production needs. The characteristics of these slopes are high elevation, large toe, and good lithology. Ordinary mechanical excavation has difficulties such as large construction difficulty and hard rock mass fragmentation. Completing the reconstruction and expansion of slopes by one-time blasting excavation has difficulties such as large construction difficulty, large blasting influence range, and casualties caused by slope failure. Therefore, it is very important to study the working conditions of small-scale multi-stage blasting for blasting excavation, which can not only reconstruct and expand high-steep slopes, but also control the explosive dosage to reduce the influence of the damaged area and control the slope stability. At present, most scholars have studied the blasting excavation of first-level slopes more, while the research on the damage influence of multi-stage slope blasting excavation is less, and for some rock masses, there may be blasting damage influences at two levels or more. The rock mass in this part of the damaged area determines whether the slope will have a small-scale slip. If the slope has a small-scale collapse, it will have irreversible effects on road damage, casualties, and economic damage. Therefore, to ensure the long-term safety of transportation infrastructure, it is crucial to deeply study the influence of engineering behavior on high-steep rock slopes.

[0003] In view of the fact that the existing evaluation of the blasting damage area of the first-level slope does not consider the damage of the rock mass behind the toe of the slope, and the existing material attenuation does not consider the influence of multi-stage slope blasting, these results lead to a large error between the slope safety factor and the actual result. Therefore, it is necessary to design a method for quantitatively analyzing the multi-stage blasting damage weakening factor. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for evaluating multi-stage blasting disturbance and cumulative damage of high-steep slopes in view of the deficiencies mentioned in the above background art.

[0005] To solve the above technical problem, the technical solution provided by the present invention is: a method for evaluating multi-stage blasting disturbance and cumulative damage of high-steep slopes, characterized in that it includes the following steps:

[0006] Step 1: Obtain slope-related parameters and blasting parameters;

[0007] Step 2: Draw a schematic diagram of the excavation damage area range under the first-level excavation based on the excavation disturbance factor and the depth of the excavation damage area obtained in Step 1, and solve the material deterioration parameters under the first-level damage area;

[0008] Step 3: Conduct the second blasting in the corresponding range and solve the material parameters after the second blasting excavation;

[0009] Step 4: Conduct the next excavation until the blasting excavation condition is completed.

[0010] Furthermore, the specific steps of Step 2 are as follows:

[0011] Step 1: Input the first excavation disturbance factor required by the model;

[0012] Step 2: Based on the depth of the excavation damage zone, delimit the scope of the excavation damage zone, and substitute the excavation disturbance factor into the Hoek-Brown criterion to solve the H-B parameters and material parameters;

[0013] Step 3: Solve the slope stability coefficient for one-time blasting excavation.

[0014] Furthermore, the specific steps of Step 3 are as follows:

[0015] Step 1: Input the excavation disturbance factor of Step 2;

[0016] Step 2: Solve the material parameters after the excavation of Step 2, conduct a cumulative damage analysis on the rock mass subjected to the first-stage and second-stage blasting, and use the corresponding cumulative damage parameters to attenuate the material parameters;

[0017] Step 3: Solve the slope stability coefficient after the excavation of Step 2.

[0018] Furthermore, if the safety factor in Step 3 is less than or equal to 1.2, corresponding support measures need to be adopted to ensure the stability of the slope.

[0019] After adopting the above method, the present invention has the following advantages: The present invention discloses a new range of blasting damage zones. After each stage of blasting, the slope surface and the slope toe will be affected by blasting disturbances. A deterioration ratio factor of the rock mass slope material parameters under each stage of blasting excavation is added and applied to the working conditions of multi-stage slope blasting excavation. The influence of the cumulative damage rock mass on the slope stability is considered. While being more in line with the actual working conditions, the variation of the safety factor of multi-stage blasting excavation of rock slopes is explored. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a flowchart of a method for evaluating multi-stage blasting cumulative damage of the present invention;

[0021] Figure 2 is a schematic diagram of the blasting damage zone in an embodiment of the present invention;

[0022] Figure 3 is a schematic diagram of the verification of the safety factor of the damage zone model in an embodiment of the present invention;

[0023] Figure 4Schematic diagram for verifying the model error of the damage area in an embodiment of the present invention;

[0024] Figure 5 Schematic diagram of the material attenuation change in an embodiment of the present invention;

[0025] Figure 6 Schematic diagram of the change in safety factor under multi - level blasting excavation under different geological conditions in an embodiment of the present invention; Detailed implementation manners

[0026] The present invention will be further described in detail below with reference to the accompanying drawings.

[0027] Combined with the attached Figure 1 , a method for evaluating the multi - level blasting disturbance and cumulative damage of high - steep slopes, which includes the following steps:

[0028] Step 1: Obtain the relevant parameters of the slope and the blasting parameters;

[0029] Step 2: Draw a schematic diagram of the excavation damage area range under the first - level excavation based on the excavation disturbance factor and the depth of the excavation damage area obtained in Step 1, and solve the material degradation parameters under the first - level damage area;

[0030] The specific steps of Step 2 are as follows:

[0031] The first step: Input the first - step excavation disturbance factor required by the model;

[0032] The second step: Delimit the excavation damage area range based on the depth of the excavation damage area, and substitute the excavation disturbance factor into the Hoek - Brown criterion to solve the H - B parameters and material parameters;

[0033] The third step: Solve the slope stability coefficient after one - time blasting excavation.

[0034] Step 3: Conduct the second - level blasting within the corresponding range, and solve the material parameters after the second - level blasting excavation;

[0035] The specific steps of Step 3 are as follows:

[0036] The first step: Input the second - step excavation disturbance factor;

[0037] The second step: Solve the material parameters after the second - step excavation, and conduct a cumulative damage analysis on the rock mass affected by the first - level and second - level blasting, and use the corresponding cumulative damage parameters to attenuate the material parameters;

[0038] The third step: Solve the slope stability coefficient after the second - step excavation.

[0039] Step 4: Proceed with the next excavation until the blasting excavation condition is completed. If the safety factor is less than or equal to 1.2, corresponding support measures need to be adopted to ensure the stability of the slope.

[0040] A specific embodiment is: A multi-stage blasting cumulative damage assessment method, including the following steps:

[0041] Step 1: Obtain relevant data based on blasting surveys and slope geometric data, specifically including different rock layer thicknesses, geological strength conditions, excavation disturbance factors, the range of the blasting damage zone, and rock material constants.

[0042] The Hoek-Brown Criterion is an empirical criterion widely used in rock mechanics and geotechnical engineering to describe the strength characteristics of rocks under different stress conditions. Its strength criterion is:

[0043]

[0044] In the formula: σ1 and σ3 are the maximum and minimum principal stresses at rock failure respectively; σci is the uniaxial compressive strength of the intact rock structure;

[0045] Taking the survey data of the Baihetan Hydropower Station as an example in the present invention, the relationship between the excavation disturbance factor and the excavation depth is obtained, where D1 and D2 represent the damage ranges of Type Ⅲ1 basalt and Type Ⅲ2 basalt:

[0046]

[0047] In the formula: for Type Ⅲ1 basalt, hHDZ and hEDZ are taken as 0.015m and 1.98m respectively; for Type Ⅲ2 basalt, hHDZ and hEDZ are taken as 0.74m and 3.4m respectively; d is the distance from the excavation surface; cp01 is the wave velocity of the undamaged rock mass of Type Ⅲ1 basalt, which is taken as 4.54 km / s in this article; cp02 is the undamaged wave velocity of Type Ⅲ2 basalt, which is taken as 3.94 km / s in this article.

[0048] Step 2: Solve for the rock material parameters based on Figure 2 the damage zone after the first-stage blasting.

[0049] The first step: Input the geological model parameters and blasting parameters of Step 1, including: the excavation disturbance factor D, the geological strength index GSI, and the rock material constant mi

[0050] The second step: Solve for the H-B empirical constants mb, s, and a:

[0051]

[0052] Where: GSI is the geological strength index, which is determined according to the condition of rock mass structural planes and rock mass structure, and its value ranges from 5 to 100; mi is the rock material constant, which is obtained from the triaxial compression test of intact rock; D is the weakening factor considering the disturbance of rock mass by human or natural factors.

[0053] Step 3: Input the H-B empirical constant parameters and solve for the material parameters:

[0054] In the 2002 version of the H-B criterion, the deformation modulus Erm of the rock mass is given by the following formula:

[0055]

[0056] For the deformation modulus Erm0 (D = 0) of the undamaged rock mass, it is given by the following formula:

[0057]

[0058] The generalized Hoek-Brown theorem also gives the estimation of the uniaxial compressive strength and uniaxial tensile strength of the rock mass. Taking σ3 = 0 in Equation (1), the uniaxial compressive strength σc is obtained:

[0059] σ c =σ ci s a (7)

[0060] Based on Hoek's research that the uniaxial tensile strength of brittle materials is equal to the biaxial tensile strength, the strength of the uniaxial tensile strength σt is given by Equation (8):

[0061]

[0062] For different rock mass problems, especially for slope stability problems, it is more convenient to deal with the normal stress and shear stress. Therefore, the equivalent Mohr-Coulomb cohesion c and internal friction angle

[0063]

[0064]

[0065] For the rock mass of slope engineering, σ3n and σ3max can be determined by the following formula:

[0066]

[0067] Where: H is the slope height; γ is the unit weight of the rock mass; σcm is the overall strength of the jointed rock.

[0068] Step 4: Input the rock material parameters within the damaged area range and solve for its safety factor. If it is less than 1.2, corresponding support measures need to be taken for protection.

[0069] Step 3: Conduct the excavation of the next working condition and solve the rock damage factor and the material parameters of the rock mass affected by cumulative damage:

[0070] Step 1: Solve the weakening factor of the rock mass parameters under each level of blasting excavation. Taking the blasting excavation of an n-level homogeneous slope and being affected by the n-level blasting excavation as an example:

[0071]

[0072] Equation (12) gives the weakening factor of the Hoek-Brown strength criterion parameters under each level of excavation. Among them, mb0 and s0 are the Hoek-Brown parameters without deterioration. mbi and si are the Hoek-Brown parameters of the rock mass under the i-th level of blasting excavation.

[0073]

[0074]

[0075] Equations (17)-(21) give the weakening factor of the rock mass material parameters under each level of excavation. E0, σc0, σt0, c0 are the material parameters without deterioration. Ei, σci, σti, ci are the material parameters of the rock mass under the i-th level of blasting excavation. Among them, i takes values from 1 to n according to the excavation steps.

[0076] σ3n0 and σ3ni in the formula are obtained from the following formulas:

[0077]

[0078] Step 2: After obtaining the deterioration ratio of the rock material parameters under each level of blasting excavation, based on the superposition effect under multi-level blasting excavation, this paper gives the deterioration situation of the rock mass material parameters affected by the superposition of the n-level blasting excavation:

[0079]

[0080] In the formula: mbWF and sWF are the deteriorated Hoek-Brown parameters under the excavation of the n-level slope.

[0081]

[0082] In the formula: EWF, σcWF, σtWF, cWF are the deteriorated material parameters under the excavation of the n-level slope.

[0083] Step 3: Use the strength reduction method to solve the slope stability. If the safety factor of the rock slope affected by cumulative damage is less than or equal to 1.2, corresponding support measures need to be adopted to avoid landslides or local collapses.

[0084] Step 4: Continue to complete the next-level blasting project. If a cumulative damage zone appears, calculate the size of the rock mass in the damage zone according to the method in Step 3.

[0085] The present invention also provides a storage medium storing a computer program, which is suitable for being loaded and executed by a processor to perform the cumulative damage rock mass parameter evaluation and slope stability analysis as described above.

[0086] The present invention also provides a device including a memory and a processor. The memory stores a computer program, and when the computer program is executed by the processor, it runs the cumulative damage rock mass parameter evaluation and slope stability analysis as described above.

[0087] Figure 2 Show the range of the rock mass damage zone affected by blasting excavation. The present invention divides the damage zone into two parts, where the darkest color is the strong interference zone. The rock mass excavation disturbance factor in the strong interference zone is the largest. The part with decreasing color depth is the weak interference zone. The rock mass parameters in the weak interference zone decay along the slope contour line using formula (2) or (3). This method for determining the damage zone range considers the rock mass affected by blasting excavation, and the rock mass on the slope surface (Zone1), at the slope toe (Zone2), and behind the slope toe (Zone3) will all be damaged by blasting. Compared with previous studies, the disturbance of the rock mass at the slope toe and behind the slope toe is added, and the overall damage zone becomes larger.

[0088] Figure 3 and Figure 4 Show the safety factor and error analysis under different models and different calculation examples. Among them, calculation example 1 is the steep slope blasting model; calculation example 2-1 is the first-level blasting excavation of the gentle slope model; calculation example 2-2 is the second-level blasting excavation of the gentle slope model, and the rock mass is affected by cumulative damage. a, b, and c represent idealized models, which are that the entire slope is damaged after blasting, only the slope surface is damaged after blasting, and there is no damage after blasting, respectively. It can be clearly seen that for calculation example 1 and calculation example 2-1, the present invention is within 5% of Yang et al. and within 20% of A.J. Li et al., and there are significant differences in the idealized models. However, for the rock mass affected by cumulative damage, the errors compared with Yang et al. and A.J. Li et al. reach 31.78% and 34.55%. During actual construction, the rock mass around the slope contour line of the rock slope will be affected by blasting disturbance to form an excavation damage zone. Under multi-level blasting construction, the damage to the rock mass affected by the first-level blasting is irreversible, so the rock mass affected by the second-level blasting is more likely to become unstable.

[0089] Figure 5Shows the variation diagram of material parameters (taking the modulus of deformation as an example) with depth. Taking Type Ⅲ2 basalt as an example, its damage depth is 3.4 m. From 0 m to 0.73 m is the strong damage zone, where the material parameters of the rock mass damaged by the first level and multiple levels are the smallest, and the excavation disturbance factor is the largest. Among them, the material parameter of the rock mass damaged by the first level is 4.19 GPa, while the material parameter of the rock mass damaged by two levels further decreases to 2.09 GPa. From 0.73 m to 3.4 m is the weak damage zone, and the material parameters of the rock mass gradually increase along the slope contour line until they reach the initial value of 8.37 GPa.

[0090] Figure 6 Shows that the safety factor of the rock slope continuously increases between the first step and the second step. This may be because the damage zone range is small at this time, the slope toe of the rock mass is small, and the safety factor becomes larger after excavation. After the second step, after a small change in the safety factor, it gradually decreases with the increase of the excavation steps. The blasting effect becomes more and more significant, and the rock mass affected by cumulative damage first becomes unstable. Among them, mi = 17 is the material parameter of Type Ⅲ2 basalt, representing the original slope.

[0091] In a specific embodiment, the slope-related parameters and blasting parameters include different rock layer thicknesses, original slope geometric parameters, geological strength parameter GSI, rock material constant mi, excavated slope area, excavation damage factor, boundary between the strong and weak interference zones after excavation, and boundary between the weak interference and non-interference zones after excavation.

[0092] In a specific embodiment, the Hoek-Brown parameters and material parameters include Hoek-Brown strength parameters mb, s, a, D; modulus of deformation Erm, uniaxial compressive strength σc, uniaxial tensile strength σt, cohesion c, and internal friction angle

[0093] In a specific embodiment, the cumulative damage parameters include Hoek-Brown strength damage parameters mbWF, sWF, aWF; material damage parameters: modulus of deformation ErmWF, uniaxial compressive strength σcWF, uniaxial tensile strength σtWF, cohesion cWF, and internal friction angle

[0094] The above describes the present invention and its embodiments. This description is not restrictive, and the actual structure is not limited thereto. Generally speaking, if those of ordinary skill in the art are inspired by it and design similar structural forms and embodiments without creative work without departing from the purpose of the present invention, they should all fall within the protection scope of the present invention.

Claims

1. A method for evaluating multi - stage blasting disturbance and cumulative damage of high - steep slopes, characterized in that: It includes the following steps: Step 1: Obtain slope-related parameters and blasting parameters; Step 2: Draw a schematic diagram of the excavation damage zone range under the first-level excavation based on the excavation disturbance factor and the depth of the excavation damage zone obtained in Step 1, and solve the material degradation parameters under the first-level damage zone; Step 3: Conduct the second blasting within the corresponding range and solve the material parameters after the second blasting excavation; Step 4: Conduct the next excavation until the blasting excavation condition is completed.

2. The method for evaluating multi-level blasting disturbance and cumulative damage of high-steep slopes according to claim 1, characterized in that: The specific steps of Step 2 are as follows: The first step: Input the excavation disturbance factor required for the first step of the model; The second step: Define the excavation damage zone range based on the depth of the excavation damage zone, substitute the excavation disturbance factor into the Hoek-Brown criterion to solve the H-B parameters and material parameters; The third step: Solve the slope stability coefficient after one blasting excavation.

3. A method for evaluating multi-stage blasting disturbance and cumulative damage of high-steep slopes according to claim 1, characterized in that: The specific steps of Step 3 are as follows: The first step: Input the excavation disturbance factor of the second step; The second step: Solve the material parameters after the second step of excavation, conduct cumulative damage analysis on the rock mass subjected to the first-level and second-level blasting, and use the corresponding cumulative damage parameters to attenuate the material parameters; The third step: Solve the slope stability coefficient after the second step of excavation.

4. A method for evaluating multi-stage blasting disturbance and cumulative damage of high-steep slopes according to claim 1, characterized in that: If the safety factor in Step 3 is less than or equal to 1.2, corresponding support measures need to be adopted to ensure the stability of the slope.

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