Method for dividing impact danger area influenced by fault

Abstract

The invention discloses a method for dividing an impact dangerous area influenced by a fault. The method comprises the following steps: S1, calculating fault dislocation release energy; s2, a roadway shallow coal rock block casting speed calculation formula is obtained; s3, collecting support parameters such as roadway side anchor rods and anchor cables, and calculating support absorption energy; and S4, defining a dangerous energy index of the division of the impact dangerous area influenced by the fault, and completing the division of the impact dangerous area. According to the method, the roadway side anti-damage capability serves as the basis for dividing the dangerous areas, the dividing method for the three grades of the impact dangerous area influenced by the fault, namely the non-dangerous area, the weak dangerous area and the strong dangerous area is obtained, the grades of the impact dangerous area influenced by the fault can be accurately divided, and the method has great significance in guiding rock burst prevention and control design.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of rock burst and coal rock dynamic disaster early warning, and particularly relates to a method for dividing an impact danger zone related to fault influence. BACKGROUND

[0002] Rock burst has been one of the main dynamic disasters that have plagued the safe mining of coal mines in China. Rock burst has the characteristics of suddenness, impact, and destructiveness, and once it occurs, it will seriously threaten the life safety of mine workers and cause serious economic losses to production equipment. With the deepening of the mining of coal mines in China year by year, the number of rock bursts caused by the comprehensive influence of factors such as ground stress and geological conditions gradually increases, which poses a great threat to the safe production of coal mines.

[0003] At present, fault-type rock burst induced by fault activity accounts for a large proportion. Due to the complexity of fault structure and mining conditions, the time and region of fault-type rock burst disasters have diversity and suddenness, so the prediction and division of the impact danger zone affected by the fault become a worldwide problem. At present, many scholars have studied the prediction and division of the impact danger zone affected by the fault and have obtained certain results, but there are still deficiencies: (1) the division of the impact danger zone is too rough; (2) the division of the impact danger zone lacks theoretical basis. According to the damage scene of coal rock dynamic disaster, the damage degree of the roadway shoulder part is larger, which is caused by the low support strength of the roadway shoulder part. Therefore, the present application takes the damage resistance of the roadway shoulder part as the basis for dividing the danger zone, obtains a division method of three levels of the impact danger zone affected by the fault, i.e. no danger zone, weak danger zone, and strong danger zone, can accurately divide the impact danger level affected by the fault, and has important significance for guiding the rock burst prevention and control design. SUMMARY

[0004] The present application provides a method for dividing the impact danger zone affected by the fault, takes the damage resistance of the roadway shoulder part as the basis for dividing the danger zone, realizes accurate division of the impact danger zone affected by the fault and guides the rock burst prevention and control design, and overcomes the problems of rough division range, poor accuracy, and difficulty in guiding the rock burst prevention and control design in the prior art.

[0005] In order to achieve the above-mentioned purpose, the technical scheme of the present application is as follows:

[0006] A method for dividing the impact danger zone affected by the fault, taking the damage resistance of the roadway shoulder part as the basis for dividing the danger zone, comprising the following steps:

[0007] S1, collect fault throw, fault strike effective length, shear modulus of fault wall rock, width parameters of fault wall rock, according to mining deployment, evaluate far-field shear displacement before and after fault slip and shear displacement before and after fault zone slip, calculate fault dislocation release energy according to the following formula:

[0008]

[0009] In the formula, W is the fault dislocation release energy; z is the effective length of the fault strike; h2 is the fault throw; G is the shear modulus of the fault wall rock; S1, S2 are the far-field shear displacement before and after fault slip respectively; u1, u2 are the shear displacement before and after the fault zone slip respectively; 2X is the width of the fault wall rock;

[0010] S2, according to the relationship between peak particle velocity and the distance from the hypocenter to rockburst impact damage, rockburst intensity, and the relationship between magnitude and energy established by A. McGarr, the coal and rock block projection velocity v calculation formula in the shallow part of the roadway is obtained:

[0011]

[0012] In the formula, W is the energy of the seismic wave at the hypocenter, J; S is the distance from the hypocenter to the impact damage; v is the coal and rock block projection velocity;

[0013] Suppose the thickness of the surrounding rock of the roadway side part participating in the projection, that is, the depth of the roadway relaxation circle, is L, and the kinetic energy formula of the surrounding rock in the shallow part of the roadway under the action of the seismic wave is: s = 0.5ρLv 2 ;

[0014] Substitute the kinetic energy formula into the coal and rock block projection velocity v calculation formula in the shallow part of the roadway to obtain:

[0015]

[0016] In the formula: L is the depth of the roadway relaxation circle; ρ is the coal and rock density; S is the distance from the hypocenter to the impact damage; W is the earthquake-inducing fault dislocation release energy in step S1;

[0017] S3, collect the support parameters of the anchor rod and anchor cable of the roadway side part, and calculate the support absorbed energy W z according to the following formula:

[0018]

[0019] In the formula, n g , n s are the number of anchor rods in the anchor rod support unit and the number of anchor cables in the anchor cable support unit of the roadway side part respectively; m g , m s are the energy that can be absorbed by a single anchor rod and a single anchor cable respectively; lg l s These represent the lengths of the bolt support unit and the cable support unit along the roadway, respectively; h is the roadway height.

[0020] S4. Define the hazard energy index T for the classification of impact hazard zones affected by faults, and complete the classification of impact hazard zones; the formula for the hazard energy index T for the classification of impact hazard zones affected by faults is:

[0021]

[0022] In the formula, W h The energy of the shallow surrounding rock in the tunnel caused by the seismic wave; W z It absorbs energy for tunnel support.

[0023] Impact hazard zones are classified according to the hazard energy index T. Considering safety, when T is greater than 1, there is a strong hazard; when T is not less than 0.6 and not greater than 1, there is a weak hazard; and when T is less than 0.6, there is no hazard, as shown in the table below.

[0024] T <0.6 0.6～1.0 1.0< mine earthquake danger energy index mine earthquake danger none weak

[0025] As an improvement to the above technical solution, the hazardous energy index T of the roadway sidewall affected by fault impact is used as the basis for delineating the impact hazard zone. The calculation formula for the hazardous energy index T of the roadway sidewall is as follows: Among them W h Wz represents the energy generated by the seismic wave in the shallow surrounding rock of the roadway; Wz represents the energy absorbed by the roadway support.

[0026] When T>1, the impact hazard zone affected by the fault is classified as a high-risk zone;

[0027] When 0.6≦T≦1, the impact hazard zone affected by the fault is classified as a weak hazard zone;

[0028] When T < 0.6, the impact hazard zone affected by the fault is classified as a no-hazard zone.

[0029] As an improvement to the above technical solution, the distance S from the epicenter to the impact failure is used as the basis for delineating the impact hazard zone. The distance S from the epicenter to the impact failure is given by the formula... It is derived from this;

[0030] When the distance from the epicenter The impact hazard zone affected by the fault is divided into a weak hazard zone;

[0031] When the distance from the epicenter The impact hazard zone affected by the fault is divided into a weak hazard zone;

[0032] When the distance from the epicenter The impact danger zone affected by the fault is divided into a strong danger zone.

[0033] Compared with the prior art, the present application has the advantages and positive effects that:

[0034] The present application takes the anti-destroying capacity of the roadway side as the basis for dividing the danger zone, obtains the dividing method of three levels of the impact danger zone affected by the fault, namely, no danger zone, weak danger zone and strong danger zone, can accurately divide the level of the impact danger zone affected by the fault, and has important significance for guiding the design of the rock burst prevention and control. BRIEF DESCRIPTION OF DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description only show some embodiments of the present application, and any modification, equivalent replacement, improvement, etc. obtained by those skilled in the art without creative labor should be included in the protection scope of the present application.

[0036] strong Flowchart of the present application; DETAILED DESCRIPTION

[0037] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, but not all the embodiments. Any modification, equivalent replacement, improvement, etc. obtained by those skilled in the art based on the embodiments in the present application without creative labor should be included in the protection scope of the present application.

[0038] By Fig. 1 It can be known that the present application relates to a dividing method of an impact danger zone affected by a fault, comprising the following steps:

[0039] Step 1: calculation of energy released by fault dislocation. Collect parameters such as fault throw, effective length of fault strike, shear modulus of fault surrounding rock, width of fault surrounding rock, etc. According to the mining deployment, evaluate the far-field shear displacement before and after the fault slip and the shear displacement before and after the fault zone slip, and calculate the energy released by fault dislocation according to the following formula:

[0040]

[0041] In the formula, W is the energy released by fault dislocation; z is the effective length of fault strike; h2 is the fault throw; G is the shear modulus of fault surrounding rock; S1 and S2 are respectively the far-field shear displacement before and after the fault slip; u1 and u2 are respectively the shear displacement before and after the fault zone slip; and 2X is the width of the fault surrounding rock.

[0042] Step 2: Calculation of energy input to the surrounding rock of the tunnel.

[0043] Based on the relationships established by A. McGarr regarding peak particle velocity, distance from the epicenter to rockburst impact damage, rockburst intensity, and magnitude versus energy, then:

[0044] The formula for calculating the ejection velocity v of coal and rock blocks in the shallow part of the roadway can be obtained as follows:

[0045]

[0046] In the formula, W is the energy of the seismic wave at the source, in J; S is the distance from the center of the source to the impact failure; and v is the ejection velocity of the coal and rock block.

[0047] Based on the site conditions of coal and rock dynamic disasters, the sidewalls of general roadways are generally severely damaged, which is due to the low strength of the sidewall support. Therefore, the resistance to damage of the roadway sidewalls is used as the basis for delineating dangerous zones. Assuming the thickness of the surrounding rock in the roadway sidewalls involved in the impact (i.e., the depth of the loosened zone) is L, the kinetic energy of the shallow surrounding rock in the roadway under the action of the seismic wave is:

[0048] W s =0.5ρLv 2 (3)

[0049] Substituting (3) into (2), we can obtain the energy input W of the surrounding rock of the tunnel at a distance of S meters from the fault. h :

[0050]

[0051] In the formula: L is the depth of the loosened zone of the roadway; ρ is the density of coal and rock; S is the distance from the epicenter to the impact failure; W is the energy released by the induced fault displacement in step 1.

[0052] Step 3: Calculation of energy absorbed by tunnel support. Collect support parameters such as roadway sidewall anchor bolts and cables, and calculate the energy absorbed by the support (W) according to the following formula. z :

[0053]

[0054] In the formula, n g n s These represent the number of anchor bolts in the roadway side anchor bolt support unit and the number of anchor cables in the cable anchor support unit, respectively; m g m s These represent the energy absorption capacity of a single anchor bolt and the energy absorption capacity of a single anchor cable, respectively. g l s , respectively, represent the lengths of the bolt support unit and the cable support unit along the roadway; h is the roadway height.

[0055] Step 4: Determining Impact Hazard Indicators and Scope of Impact Hazard Zones. Define the hazard energy indicators for dividing impact hazard zones, and then delineate the impact hazard zones. The method for using hazard energy indicators for zone division is as follows:

[0056] The hazard energy index T for the classification of impact hazard zones due to fault influence is defined as follows:

[0057]

[0058] In the formula, W h The energy of the shallow surrounding rock in the tunnel caused by the seismic wave; W z It absorbs energy for tunnel support.

[0059] Impact hazard zones are classified according to the hazard energy index T. Considering safety, when T is greater than 1, there is a strong hazard; when T is not less than 0.6 and not greater than 1, there is a weak hazard; and when T is less than 0.6, there is no hazard, as shown in the table below.

[0060] Fig. 1 <0.6 0.6～1.0 1.0< T mine earthquake danger energy index mine earthquake danger none

[0061] The impact range of the shock source can be derived as shown in the table below:

[0062]

[0063] The distance S from the earthquake source mentioned above is a spatial distance.

[0064] This invention uses the roadway sidewall's resistance to damage as the basis for classifying dangerous areas, and obtains a method for classifying the impact hazard zone affected by faults into three levels: no danger zone, weak danger zone, and strong danger zone. This method can accurately classify the impact hazard zone level affected by faults, which is of great significance for guiding the design of rockburst prevention and control.

[0065] The following examples illustrate this point:

[0066] The No. 105 working face of a certain mine has a strike length of 2680m and a working face length of 290m. The average thickness of the coal seam is 6.5m, and the average burial depth is 700m, making it a near-horizontal coal seam. The immediate roof is mainly composed of approximately 9.1m thick soft to semi-hard sandy mudstone and fine sandstone, while the basic roof is approximately 21.1m thick medium-grained sandstone, and the floor is sandy mudstone. The working face has poor geological structure. The maximum fault displacement is 10m, the effective strike length of the sliding fault is approximately 300m, the shear modulus of the fault zone is 6.5GPa, the far-field shear displacement before the fault slip is 0.07m, and the far-field shear displacement after the slip is 0.02m. The shear displacements before and after the slip are 0.001m and 0.06m, respectively, and the width of the surrounding rock of the fault zone is approximately 20m. Since rockbursts in this mine mostly occur in the roadways on the side facing the working face, the safety level of the roadways is evaluated using the auxiliary transport roadway of the working face as an example. The auxiliary transport roadway has a rectangular cross-section, 5200mm wide and 3800mm high, and is supported by a combination of anchor, mesh, and cable. The support parameters are shown in Table 2.

[0067] Table 2 Support Parameters for Auxiliary Transport Roadway at Working Face

[0068]

[0069] Based on the materials used for roadway support, each anchor bolt is determined to absorb 20KJ of energy, and each anchor cable to absorb 50KJ of energy. Field tests showed that the average depth of the loosened zone in the roadway was 1.2m, and the density of the coal was 1.35g / cm³. 3 .

[0070] Step 1: Calculation of energy released by fault displacement. Fault displacement h2 = 10m; effective fault strike length z = 300m; shear modulus of surrounding rock G = 6.5GPa; far-field shear displacements before and after fault slippage are S1 = 0.07m and S2 = 0.02m respectively; shear displacements before and after fault zone slippage are u1 = 0.001m and u2 = 0.06m respectively; width of surrounding rock is 2X = 20m. Substituting into formula (1), the energy released by fault displacement W≈1.54*10 9 J.

[0071] Step 2: Calculation of energy input to the surrounding rock of the roadway, with coal density ρ = 1.35 g / cm³. 3 The depth of the loosened zone of the surrounding rock is L = 1.2m. The energy input to the surrounding rock of the tunnel at a distance of S meters from the fault can be calculated using formula (4):

[0072]

[0073] Step 3: Calculation of energy absorption for tunnel support. From the parameters in Table 2, n can be obtained. g =10; n s =6; l g =900mm; l s=The energy absorption of a single 1800mm anchor bolt and a single anchor cable are respectively m g =20KJ; m s =50KJ; roadway height h=3800mm. Substituting into formula (5), we get the support absorption energy W. z =102.33KJ / m 2

[0074] Step 4: Determining the impact hazard index and the scope of the impact hazard area. Define the hazard energy index for the division of the impact hazard area and divide the impact hazard area accordingly. Calculate the hazard energy index according to formula (6):

[0075]

[0076] When T > 1, i.e., S < 26.40m, it is a highly dangerous area.

[0077] When 0.6 < T < 1, i.e., 26.40m < S < 34.08, it is a weak danger zone.

[0078] When T < 0.6, i.e., S > 34.08, it is a no-danger zone.

[0079] weak strong source distance (spatial distance m) danger classification when the source distance S > 34.08 none danger area when the source distance 26.40 ≤ S ≤ 34.08 weak danger area when the source distance S < 26.40 strong danger area

[0080] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other modifications under the guidance of the present invention without departing from the spirit and scope of the claims. All of these modifications are within the protection scope of the present invention.

Claims

1. A method for delineating impact hazard zones based on fault influence, characterized in that: Includes the following steps: S1. Collect parameters such as fault displacement, effective length of fault strike, shear modulus of surrounding rock, and width of surrounding rock. Based on the mining deployment, assess the far-field shear displacement before and after fault slip and the shear displacement of the fault zone before and after slip. Calculate the energy released by fault displacement according to the following formula: In the formula, W is the energy released by fault displacement; z is the effective length of the fault strike; h2 is the fault displacement; G is the shear modulus of the fault surrounding rock; S1 and S2 are the far-field shear displacements before and after fault slip; u1 and u2 are the shear displacements before and after fault zone slip; 2X is the width of the fault surrounding rock. S2. Based on the relationships established by A. McGarr between peak particle velocity, distance from the epicenter to rockburst impact damage, rockburst intensity, and magnitude and energy, the formula for calculating the ejection velocity v of shallow coal and rock blocks in the roadway is obtained: In the formula, W is the energy of the seismic wave at the source, in J; S is the distance from the center of the source to the impact failure; v is the ejection velocity of the coal and rock block. Let L be the thickness of the surrounding rock in the tunnel sidewalls involved in the projectile motion, i.e., the depth of the loosened zone in the tunnel. The formula for the kinetic energy of the shallow surrounding rock in the tunnel under the action of the seismic wave is: W s =0.5ρLv 2 ; Substituting the kinetic energy formula into the formula for calculating the ejection velocity v of coal and rock blocks in the shallow part of the roadway, we get: Where: L is the depth of the loosened zone in the roadway; ρ is the density of coal and rock; S is the distance from the epicenter to the impact failure; W is the energy released by the induced fault displacement in step S1; S3. Collect the support parameters such as anchor bolts and anchor cables on the roadway sidewalls, and calculate the support absorption energy W according to the following formula. z : In the formula, n g n s These represent the number of anchor bolts in the roadway side anchor bolt support unit and the number of anchor cables in the cable anchor support unit, respectively; m g m s These represent the energy absorption capacity of a single anchor bolt and the energy absorption capacity of a single anchor cable, respectively. g l s These represent the lengths of the bolt support unit and the cable support unit along the roadway, respectively; h is the roadway height. S4. Define the hazard energy index T for the classification of impact hazard zones affected by faults, and complete the classification of impact hazard zones; the formula for the hazard energy index T for the classification of impact hazard zones affected by faults is: In the formula, W h The energy of the shallow surrounding rock in the tunnel caused by the seismic wave; W z It absorbs energy for tunnel support.

2. The method for delineating impact hazard zones due to fault influence as described in claim 1, characterized in that: The hazardous energy index T of the roadway sidewall affected by fault impact is used as the basis for classifying impact hazard zones. The formula for calculating the hazardous energy index T of the roadway sidewall is as follows: Among them W h Wz represents the energy generated by the seismic wave in the shallow surrounding rock of the roadway; Wz represents the energy absorbed by the roadway support. When T>1, the impact hazard zone affected by the fault is classified as a high-risk zone; When 0.6≦T≦1, the impact hazard zone affected by the fault is classified as a weak hazard zone; When T < 0.6, the impact hazard zone affected by the fault is classified as a no-hazard zone.

3. The method for delineating impact hazard zones due to fault influence as described in claim 1, characterized in that: The distance S from the epicenter to the impact failure is used as the basis for delineating impact hazard zones. The distance S from the epicenter to the impact failure is given by the formula... It is derived from this; When the distance from the epicenter The impact hazard zone affected by the fault is divided into a weak hazard zone; When the distance from the epicenter The impact hazard zone affected by the fault is divided into a weak hazard zone; When the distance from the epicenter The impact hazard zone affected by the fault is classified as a high-risk zone.

Images