CN113984532B - Determination method and system for potential damage partition of deep-buried fracture surrounding rock - Google Patents
Determination method and system for potential damage partition of deep-buried fracture surrounding rock Download PDFInfo
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Abstract
The invention relates to a method and a system for determining potential damage partition of deep-buried fracture surrounding rock, comprising the following steps: sampling surrounding rock cracks of the engineering rock body, and determining surrounding rock crack information of each surrounding rock crack; determining a plurality of target radius values according to the surrounding rock fracture information; the target radius value is the maximum radius value in all surrounding rock cracks in the same group; performing a surrounding rock fracture toughness test on the engineering rock mass to determine the surrounding rock fracture toughness; performing a rock mass stress field test on the engineering rock mass to determine an average stress field of the engineering rock mass; determining a maximum stress intensity factor by utilizing a fracture mechanics formula according to the maximum radius value and the average stress field; and determining potential damage subareas of the surrounding rock according to the maximum stress intensity factor and the fracture toughness of the surrounding rock. The invention can improve the precision of destroying the partition.
Description
Technical Field
The invention relates to the technical field of engineering surrounding rocks, in particular to a method and a system for determining potential damage partition of a deep-buried fracture surrounding rock.
Background
In underground works, due to the differences in the shape, the excavation speed and the excavation means of the excavation works, excavation damage zones (Excavation Damage Zone, EDZ) are formed around the excavated section. Under the condition of excavation unloading, stress redistribution causes the expansion and penetration of the pre-existing cracks of the rock mass until regular splitting damage is formed. Stress conditions and rock mass structure are the most important factors in controlling fracture damage. On one hand, high ground stress is a main characteristic of deep underground engineering, on the other hand, excavation is accompanied with adjustment of rock mass structural state, and a series of processes of closing, opening, expanding, connecting and the like of microscopic cracks are caused by large-scale excavation, so that macroscopic brittle fracture is finally formed. The main determination methods of EDZ at present comprise acoustic wave test, stress displacement measurement, drilling shooting and the like, and basically, the methods need additional workload to cooperate with test work, and the test range is limited. The existing EDZ partition determination method mainly considers the influence of one of two factors, the analysis method based on the stress condition does not consider the influence of existing cracks in the rock mass, and the conventional rock mass crack statistical measurement also neglects the transformation of the high-stress excavation condition on the existing cracks of the surrounding rock. Therefore, it is highly desirable to propose a determination method for determining potential damage zones of deep-buried fracture surrounding rock based on stress conditions and rock mass structure.
Disclosure of Invention
The invention aims to provide a method and a system for determining a potential damage partition of a deep-buried fracture surrounding rock so as to improve the precision of the damage partition.
In order to achieve the above object, the present invention provides the following solutions:
A method for determining a potential damage partition of a deep-buried fracture surrounding rock, comprising:
Sampling surrounding rock cracks of the engineering rock body, and determining surrounding rock crack information of each surrounding rock crack;
determining a plurality of target radius values according to the surrounding rock fracture information; the target radius value is the maximum radius value in all surrounding rock cracks in the same group;
Performing a surrounding rock fracture toughness test on the engineering rock mass to determine the surrounding rock fracture toughness;
Performing a rock mass stress field test on the engineering rock mass to determine an average stress field of the engineering rock mass;
determining a maximum stress intensity factor by utilizing a fracture mechanics formula according to the maximum radius value and the average stress field;
and determining potential damage subareas of the surrounding rock according to the maximum stress intensity factor and the fracture toughness of the surrounding rock.
Optionally, determining a plurality of target radius values according to the surrounding rock fracture information; the target radius value is the maximum radius value in all surrounding rock cracks in the same group, and specifically comprises the following steps:
projecting the rock mass fracture information on a Schmidt equal-area red flat projection network according to a normal line, and grouping rock mass fractures according to a density value line of the Schmidt equal-area red flat projection network;
Performing trace length conversion on the trace lines of the rock mass cracks in the same group to determine the radius of the rock mass cracks;
and sequencing and regression analysis are carried out on the rock mass fracture radii of the same group, and the maximum radius value of each group of surrounding rock fractures is determined.
Optionally, the performing a surrounding rock fracture toughness test on the engineering rock body, and determining the surrounding rock fracture toughness specifically includes:
Performing a center straight crack semicircular disc fracture toughness test on a test sample of the engineering rock body by using a rock mechanical testing machine, and determining I-type fracture toughness in the surrounding rock fracture toughness;
And carrying out a three-axis compression shear test on a test sample of the engineering rock mass by using a rock mechanical testing machine, and determining the type II fracture toughness in the fracture toughness of the surrounding rock.
Optionally, the rock mass stress field test comprises a hydraulic fracturing method and a stress relief method.
Optionally, the step of performing a rock mass stress field test on the engineering rock mass to determine an average stress field of the engineering rock mass specifically includes:
performing a rock stress field test on the engineering rock mass to determine the normal stress and the shear stress of a fracture surface;
And determining an average stress field according to the positive stress and the shear stress.
Optionally, the determining the potential damage partition of the surrounding rock according to the maximum stress intensity factor and the fracture toughness of the surrounding rock specifically includes:
Judging whether the maximum stress intensity factor meets a first judging condition or whether the maximum stress intensity factor meets a second judging condition, and obtaining a first judging result; the first judgment condition is that the I-type stress intensity factor or the III-type stress intensity factor in the maximum stress intensity factors is larger than the I-type fracture toughness; the second judgment condition is that the type II stress intensity factor in the maximum stress intensity factors is larger than the type II fracture toughness;
If the first judgment result indicates that the maximum stress intensity factor meets the first judgment condition or the maximum stress intensity factor meets the second judgment condition, the fracture is determined to be damaged, and the surrounding rock fracture is a surrounding rock potential damage partition.
A potentially damaging zonal determination system for a deep fracture surrounding rock, comprising:
The sampling module is used for sampling surrounding rock cracks of the engineering rock body and determining surrounding rock crack information of each surrounding rock crack;
The maximum radius value determining module is used for determining a plurality of target radius values according to the surrounding rock fracture information; the target radius value is the maximum radius value in all surrounding rock cracks in the same group;
The surrounding rock fracture toughness testing module is used for testing the fracture toughness of the surrounding rock of the engineering rock body and determining the fracture toughness of the surrounding rock;
The rock mass stress field testing module is used for testing the rock mass stress field of the engineering rock mass and determining the average stress field of the engineering rock mass;
the maximum stress intensity factor determining module is used for determining a maximum stress intensity factor by utilizing a fracture mechanics formula according to the maximum radius value and the average stress field;
And the surrounding rock potential damage partition determining module is used for determining a surrounding rock potential damage partition according to the maximum stress intensity factor and the surrounding rock fracture toughness.
Optionally, the maximum radius value determining module specifically includes:
the projection and grouping unit is used for projecting the rock mass fracture information on a Schmidt equal-area red flat projection net according to a normal line, and grouping the rock mass fracture according to a density value line of the Schmidt equal-area red flat projection net;
the trace length conversion unit is used for carrying out trace length conversion on the trace lines of the rock mass cracks in the same group and determining the radius of the rock mass cracks;
And the sequencing and regression analysis unit is used for sequencing and regression analysis of the rock mass fracture radii of the same group and determining the maximum radius value of each group of surrounding rock fractures.
Optionally, the surrounding rock fracture toughness testing module specifically includes:
the I-type fracture toughness determining unit is used for testing the fracture toughness of the center straight crack semicircular disc of the test sample of the engineering rock body by using a rock mechanical testing machine, and determining the I-type fracture toughness in the fracture toughness of the surrounding rock;
and the type II fracture toughness determining unit is used for carrying out a triaxial stamping shear test on the test sample of the engineering rock body by using a rock mechanical testing machine to determine the type II fracture toughness in the surrounding rock fracture toughness.
Optionally, the rock mass stress field test comprises a hydraulic fracturing method and a stress relief method.
According to the specific embodiment provided by the invention, the invention discloses the following technical effects:
the invention provides a method and a system for determining potential damage partition of a deep-buried fracture surrounding rock, which are used for determining the maximum radius value of a fracture according to rock mass fracture information; performing a surrounding rock fracture toughness test on the engineering rock mass to determine the surrounding rock fracture toughness; carrying out a rock stress field test on the engineering rock mass to determine an average stress field of the engineering rock mass; determining a maximum stress intensity factor by utilizing a fracture mechanics formula according to the maximum radius value and the average stress field; and determining potential damage subareas of the surrounding rock according to the maximum stress intensity factor and the fracture toughness of the surrounding rock. By considering the fracture toughness of the surrounding rock and the stress information of the engineering rock mass when determining the potential damage partition of the surrounding rock, the structural information of the rock mass is considered, so that the precision of the damage partition is improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the drawings that are needed in the embodiments will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a flow chart of a method for determining potential damage zones of deep-buried fracture surrounding rock provided by the invention;
FIG. 2 is a schematic diagram of a line layout of a fine line measurement method provided by the present invention;
FIG. 3 is a normal equal area right-angle projection view of a structural surface provided by the invention;
FIG. 4 is a schematic diagram of the statistical result of the underground engineering surrounding rock fracture provided by the invention;
FIG. 5 is a schematic representation of the test piece patterns required for the fracture toughness test of the rock provided by the present invention;
FIG. 6 is a schematic diagram of IIIIII-type stress intensity factors for specific six points in a surrounding rock provided by the invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The invention aims to provide a method and a system for determining a potential damage partition of a deep-buried fracture surrounding rock so as to improve the precision of the damage partition.
In order that the above-recited objects, features and advantages of the present invention will become more readily apparent, a more particular description of the invention will be rendered by reference to the appended drawings and appended detailed description.
Most of the damage of the EDZ of the high-stress rock mass is started from fracture damage, after the cracks in the rock mass are expanded, adjacent small cracks are communicated into through large cracks, and the adjacent large cracks are mutually cut, so that the integrity and strength properties of the rock mass are damaged. Fracture of a rock mass generally begins with an existing fracture. Existing fractures are primarily structural fractures formed during geological history or unloading fractures caused by excavation. These fissures may all be grouped according to their cause.
The same set of fractures often have the same or similar occurrence. According to the theory of fracture mechanics, for a certain group of cracks, the stress intensity factor of the largest crack in the rock mass is calculated, and the normal stress sigma n and the shear stress tau on the crack surface need to be calculated first. According to fracture mechanics theory, the stress intensity factor of the fracture is proportional to the fracture radius to the power of 0.5, and the longer the fracture radius alpha is, the larger the stress intensity factor is. Thus, the maximum fracture radius α m for each group of fractures of the rock mass can be determined by fracture statistics. On the basis, the stress state sigma ij obtained through numerical calculation and the longest radius alpha m of each group of cracks are brought into a fracture mechanics formula to be calculated, and then the maximum stress intensity factor in the surrounding rock can be obtained. The maximum stress intensity factor varies according to the type of fracture and the grouping of the fractures. And finally, determining the fracture toughness of the surrounding rock through fracture mechanics tests of surrounding rock samples, so as to determine the most likely fracture and damage positions of the surrounding rock. The method can guide engineers to obtain key reinforcement areas through random fracture statistical analysis before excavation, and prevent surrounding rock from being broken and unstable.
As shown in FIG. 1, the method for determining the potential damage partition of the deep-buried fracture surrounding rock provided by the invention comprises the following steps:
Step 101: and sampling surrounding rock cracks of the engineering rock body, and determining surrounding rock crack information of each surrounding rock crack.
Step 102: determining a plurality of target radius values according to the surrounding rock fracture information; the target radius value is the maximum radius value in all surrounding rock cracks in the same group. Wherein, a plurality of target radius values are determined according to the surrounding rock fracture information; the target radius value is the maximum radius value in all surrounding rock cracks in the same group, and specifically comprises the following steps:
And projecting the rock mass fracture information on a Schmidt equal-area red flat projection network according to a normal line, and grouping the rock mass fractures according to a density value line of the Schmidt equal-area red flat projection network.
And performing trace length conversion on the trace lines of the rock mass cracks in the same group to determine the radius of the rock mass cracks.
And sequencing and regression analysis are carried out on the rock mass fracture radii of the same group, and the maximum radius value of each group of surrounding rock fractures is determined.
Step 103: and performing a surrounding rock fracture toughness test on the engineering rock mass to determine the surrounding rock fracture toughness. The method for testing the fracture toughness of the surrounding rock of the engineering rock body comprises the following steps of:
And testing the fracture toughness of the center straight crack semicircular disc by using a rock mechanical testing machine to test samples of the engineering rock mass, and determining the type I fracture toughness in the fracture toughness of the surrounding rock.
And carrying out a three-axis compression shear test on a test sample of the engineering rock mass by using a rock mechanical testing machine, and determining the type II fracture toughness in the fracture toughness of the surrounding rock.
Step 104: and carrying out a rock mass stress field test on the engineering rock mass to determine the average stress field of the engineering rock mass. Wherein the rock mass stress field test comprises a hydraulic fracturing method and a stress relief method.
In practical application, the step of testing the rock mass stress field of the engineering rock mass, and determining the average stress field of the engineering rock mass specifically comprises the following steps:
And testing the rock stress field of the engineering rock mass, and determining the normal stress and the shear stress of the fracture surface.
And determining an average stress field according to the positive stress and the shear stress.
Step 105: and determining a maximum stress intensity factor by utilizing a fracture mechanics formula according to the maximum radius value and the average stress field.
Step 106: and determining potential damage subareas of the surrounding rock according to the maximum stress intensity factor and the fracture toughness of the surrounding rock. The method for determining the potential damage partition of the surrounding rock according to the maximum stress intensity factor and the fracture toughness of the surrounding rock specifically comprises the following steps:
Judging whether the maximum stress intensity factor meets a first judging condition or whether the maximum stress intensity factor meets a second judging condition, and obtaining a first judging result; the first judgment condition is that the I-type stress intensity factor or the III-type stress intensity factor in the maximum stress intensity factors is larger than the I-type fracture toughness; and the second judgment condition is that the type II stress intensity factor in the maximum stress intensity factors is larger than the type II fracture toughness.
If the first judgment result indicates that the maximum stress intensity factor meets a first judgment condition or the maximum stress intensity factor meets a second judgment condition, the fracture is determined to be damaged, and the surrounding rock fracture is a potential damage partition of the surrounding rock.
The invention also provides a method for determining the potential damage partition of the deep-buried fracture surrounding rock, which is more specific in practical application.
Step one: surrounding rock fracture sampling statistics
1.1 Rock mass random fracture accurate survey line sampling
Firstly, according to a rock mass structural plane spacing method suggested in an engineering rock mass grading standard GBT50218-2014 annex B, a fine survey line method is adopted to carry out field random sampling statistics on surrounding rock cracks of a target tunnel, as shown in figure 2. The accurate measuring method is to arrange a measuring line on the exposed surface of the rock mass, sequentially measure the intersection point position, the inclination angle position, the trace length and the gap width of the structural surface on the measuring line, and identify the roughness, the filling material and the filling degree of the structural surface, thereby obtaining the rock mass crack information.
1.2 Determination of random fracture groupings from the yield projections
According to the principle that the same group of cracks often have the same or similar occurrence, random occurrence in the acquired rock mass crack information is projected on a Stonet equal-area bare-flat projection network according to normal, as shown in fig. 3, the rock mass cracks can be divided into different groups according to occurrence according to the density value line of points (poles), and dominant occurrence, namely tendency and inclination angle, of each occurrence group can be acquired.
1.3 Determination of fracture radius calculation from trace length conversion calculation
The trace of a rock mass fracture refers to the intersection of the fracture with the measurement surface, the length of the intersection being abbreviated as trace length, denoted as l (m). According to the principle of the rounding effect of crack extension, the shape of a crack can be assumed to be a circle, and the crack centroids are randomly distributed in a three-dimensional space, so that the crack trace length acquired by the measuring line is the chord length of the circle. According to formula (1),
Where d and a are the diameter and radius (m) of the rock mass fracture, the radius of the fracture can be calculated from the measured fracture length from equation (1).
1.4 Statistical ordering of fracture radii in the same group
According to the grouping condition of sampling, the statistics is assumed to be carried out through random sampling in the field, wherein the size of a group of fracture samples is n, and the radius values of n fractures are arranged into a sequence as follows:
a1＜a2＜a3＜a4＜.....＜an
it is assumed that the distribution of the radius a subject to the density function f (a) is obtained by regression analysis. The distribution function is as shown in formula (2):
1.5 maximum radius calculation of fracture
According to a maximum function max (a 1,a2,a3.....an) in a statistical theory, the radius a of the group of cracks takes the maximum value, so that the probability of a n < a is:
P(an＜a)＝P{max(a1,a2,a3.....an)＜a}
＝P(a1＜a,a2＜a,a3＜a,.....,an＜a)
＝P(a1＜a)P(a2＜a)P(a3＜a).....P(an＜a)
＝[F(a)]n＝G(a)
g (a) is the maximum distribution function of a. Deriving the formula G (a) from a, and obtaining the distribution density function of the maximum value of a as
G(a)′＝g(a)＝nf(a)[F(a)]n-1
Let g (a)' =0, there is
(n-1)f2(a)＝-f′(a)F(a)
The maximum radius value a m for the set of fractures can then be written as a solution to the following set of equations.
Where f (a) is a density function of the fracture radius a, which may be specified as a different functional form, such as a normal distribution, an exponential distribution, a logarithmic distribution, a polynomial distribution, and the like.
Taking a first-level hydropower station of a brocade screen as an example, the cracks of surrounding rocks of an underground factory building mainly develop into 3 groups, and the track length of the cracks of the 3 groups is within 2m on the surrounding rocks with complete rock bodies. Taking the surrounding rock with better integrity as a research object, the statistical work is performed on the surface of the surrounding rock. The occurrence of the three sets of fissures is shown in table 1:
table 1 fracture appearance table
| Fracture group | A first group of cracks | A second group of cracks | Third group of cracks |
| Yield of shape | 154°∠71° | 24°∠75° | 223°∠63° |
Regression analysis is required for the counted fracture radius after the counting work is finished. In regression analysis, a proper density function f (a) is selected according to actual data of field statistics, so that higher fitting degree is obtained. According to the condition of field statistical data, the invention adopts an exponential function: f (a) =ae -Ba regression analysis was performed on statistics of the underground plant, obtaining a satisfactory fit. The regression analysis result of the surrounding rock fracture statistical data of the underground powerhouse of the mall power station is shown in figure 3.
Using the formulaThe maximum trace length of each set of cracks, i.e., the maximum radius am of the crack, was calculated, where B is the fitting parameter of the exponential function, and the results are shown in Table 2.
Table 2 maximum trace length table for each group of cracks
The statistical result of the underground engineering surrounding rock cracks is shown in fig. 4, wherein the abscissa in the figure is the trace length of the detected cracks, the ordinate is the number of crack strips corresponding to the corresponding trace length, x is the trace length, the unit is l/m, y is the number of strips, and the unit is n/strip. Fig. 4 (a) shows the first statistics of the first set of fractures (26 fractures total, n=26), where y= 24.782361e -8.92907x. Fig. 4 (b) shows a second statistic of the first set of cracks (47 cracks total, n=47), where y= 24.02915e -13.45693x. Fig. 4 (c) shows a third statistic for the first set of fractures, (25 fractures total, n=25) where y= 23.42015e -8.80847x. Fig. 4 (d) shows a second set of fracture first statistics, (23 total fractures, n=23), where y= 31.77098e -7.50258x, fig. 4 (e) shows a second set of fracture second statistics (38 total fractures, n=38), where y= 34.11937e -8.40944x, and fig. 4 (f) shows a second set of fracture third statistics, (43 total fractures, n=43), where y= 31.2851e -3.1847x. Fig. 4 (g) shows a first statistic for a third set of fractures, (38 fractures total, n=38), where y= 73.26811e -7.40506x. Fig. 4 (h) shows a second statistic for the third set of fractures (42 fractures total, n=42), where y= 57.74979e -12.16382x. Fig. 4 (i) shows a third statistic for a third set of cracks, (63 cracks total, n=63), where y= 82.48519e -8.94419x.
Step two: surrounding rock fracture toughness test
And collecting surrounding rock blocks on site, and processing the surrounding rock blocks into test samples indoors. According to the rock fracture toughness test method recommended by the international society of rock mechanics and engineering (ISRM) 2014, a center straight crack semicircular disc fracture toughness test of a surrounding rock sample is carried out by using a rock mechanics testing machine, as shown in fig. 5, so that the type I fracture toughness K Ic of the surrounding rock is obtained. According to the rock fracture toughness test method recommended by the international society of rock mechanics and engineering (ISRM) 2012, a triaxial compression shear test of a surrounding rock sample is carried out by using a rock mechanics testing machine to determine the type II fracture toughness K IIc of the surrounding rock, as shown in FIG. 5. Wherein, fig. 5 (a) is a schematic plan view of a fracture toughness test of a central straight-split half disc, fig. 5 (b) is a schematic cross-sectional view of a fracture toughness test of a central straight-split half disc, fig. 5 (c) is a plan view of a triaxial compression shear test, fig. 5 (d) is a plan view of a triaxial compression shear test sample, and fig. 5 (e) is a plan view of a triaxial compression shear test sample.
Step three: maximum stress intensity factor calculation
The stress intensity factor is obtained by obtaining the normal stress sigma e and the shear stress tau e on the structural surface in the rock mass. The method comprises the following specific steps:
3.1 acquisition of the ground stress field
Because of the difficulty of obtaining the stress field by numerical calculation (the numerical calculation must grasp all external boundary conditions of the rock mass, accurately grasp the spatial positions and mechanical properties of all structural surfaces in the rock mass, accurately grasp the mechanical parameters of the rock mass, and accurately calculate the internal stress field of the rock mass), the method for directly measuring the internal stress field of the rock mass by adopting the field stress test has a plurality of advantages. The on-site test means can avoid the difficult problem in numerical calculation, the accuracy of the test result depends on the accuracy degree of the test means and the test method, and the problem of mutual interference of stress fields of complex structural surfaces is not needed to be considered. The main rock stress field testing methods at present are a hydraulic fracturing method, a stress relief method and the like. After the ground stress test data are obtained, the average stress field in the rock mass is determined.
3.2 Calculation of the Positive stress and the shear stress on the fracture surface
The average stress field is projected onto the fracture surface using a slope stress equation (cauchy equation) to find the normal stress σ e and the shear stress τ e on the fracture surface. All particles in the rock mass are in an average stress field environment. The average stress field can be expressed in terms of tensors, where the average stress field is the stress state as follows:
The slope stress formula (cauchy formula) solves for the positive stress σ e and the shear stress τ e of the stress field on the structural face:
px＝σxl+τyxm+τzxn
py＝τxyl+σym+τzyn
pz＝τxzl+τzym+σzn
Where p x,py,pz is the component of stress σ v in the x, y, z directions: Positive stress on oblique section: σ e＝pxl+pym+pn n, shear stress in oblique section: From this, the normal stress and the shear stress on the structural plane can be calculated. The normal stress σ e and the shear stress τ e on the structural plane and the normal and shear stresses on the structural plane are both normal stress σ e and shear stress τ e on the fracture plane.
3.3 Maximum stress intensity factor calculation
And (3) taking the average stress field sigma ij obtained by test calculation in the surrounding rock and the longest radius a m of each group of cracks into a fracture mechanics formula for calculation, and then obtaining the maximum stress intensity factor in the surrounding rock. The maximum stress intensity factor varies according to the type of fracture and the grouping of the fractures. In the invention, underground engineering is taken as an example, 3 groups of cracks are shared in an engineering area, so 9 graphs are needed to represent the I, II and III maximum stress intensity factors of each group of cracks, three fracture modes are defined in fracture mechanics, three stress intensity factors are respectively corresponding, I is tensile fracture, II is shear fracture, and III is mixed fracture.
Step four: determining potential damage zones for surrounding rock
According to fracture mechanics theory, when the stress intensity factor K 1 of tensile fracture or the stress intensity factor K 3 of mixed fracture is greater than the fracture toughness K Ic, or the stress intensity factor K 2 of shear fracture is greater than the fracture toughness K IIc, fracture occurs. And drawing a cloud chart of the potential damage partition of the surrounding rock by introducing the maximum stress intensity factor and fracture toughness data through commercial software Tecplot.
As shown in fig. 6, in the foregoing calculation result of the underground factory building, the most likely fracture and destruction position (No. 4 point position) in the cavity is clearly indicated, and the fracture and destruction are mainly performed along the second group of cracks, so that engineers can be guided to perform key reinforcement on the second group of cracks of the No. 4 point position, and the surrounding rock fracture and instability are prevented; in the rock burst research of the high-stress hard rock tunnel, the method can also be used for calculating the most likely position of the rock burst in the surrounding rock of the chamber and determining the crack occurrence possibly causing the rock burst, thereby guiding engineers to take treatment measures. Fig. 6 (a) shows six characteristic points of the surrounding rock of the underground chamber, and fig. 6 (b) shows the calculation results of type I, II and III stress intensity factors corresponding to the characteristic points in the six surrounding rocks. In addition, the results in FIG. 6 (b) clearly show the magnitude of the stress intensity factor, wherein the surrounding rock stress intensity factor K II、KIII at the point 4 is significantly larger than at other points, which is the most likely brittle fracture in the section.
The invention provides a potential damage partition determination system for deep-buried fracture surrounding rock, which comprises the following components:
the sampling module is used for sampling surrounding rock cracks of the engineering rock body and determining surrounding rock crack information of each surrounding rock crack.
The maximum radius value determining module is used for determining a plurality of target radius values according to the surrounding rock fracture information; the target radius value is the maximum radius value in all surrounding rock cracks in the same group.
And the surrounding rock fracture toughness testing module is used for testing the fracture toughness of the surrounding rock of the engineering rock body and determining the fracture toughness of the surrounding rock.
And the rock mass stress field testing module is used for testing the rock mass stress field of the engineering rock mass and determining the average stress field of the engineering rock mass.
And the maximum stress intensity factor determining module is used for determining the maximum stress intensity factor by utilizing a fracture mechanics formula according to the maximum radius value and the average stress field.
And the surrounding rock potential damage partition determining module is used for determining a surrounding rock potential damage partition according to the maximum stress intensity factor and the surrounding rock fracture toughness.
In practical application, the maximum radius value determining module specifically includes:
And the projection and grouping unit is used for projecting the rock mass fracture information on the Schmidt equal-area red flat projection net according to a normal line, and grouping the rock mass fracture according to a density value line of the Schmidt equal-area red flat projection net.
And the trace length conversion unit is used for carrying out trace length conversion on the trace lines of the rock mass cracks in the same group and determining the radius of the rock mass cracks.
And the sequencing and regression analysis unit is used for sequencing and regression analysis of the rock mass fracture radii of the same group and determining the maximum radius value of each group of surrounding rock fractures.
In practical application, the surrounding rock fracture toughness testing module specifically comprises:
And the type I fracture toughness determination unit is used for performing a center straight crack semicircular disc fracture toughness test on a test sample of the engineering rock body by using a rock mechanical testing machine to determine type I fracture toughness in the surrounding rock fracture toughness.
And the type II fracture toughness determining unit is used for carrying out a triaxial stamping shear test on the test sample of the engineering rock body by using a rock mechanical testing machine to determine the type II fracture toughness in the surrounding rock fracture toughness.
In practical applications, the rock mass stress field test includes a hydraulic fracturing method and a stress relief method.
In the present specification, each embodiment is described in a progressive manner, and each embodiment is mainly described in a different point from other embodiments, and identical and similar parts between the embodiments are all enough to refer to each other. For the system disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant points refer to the description of the method section.
The principles and embodiments of the present invention have been described herein with reference to specific examples, the description of which is intended only to assist in understanding the methods of the present invention and the core ideas thereof; also, it is within the scope of the present invention to be modified by those of ordinary skill in the art in light of the present teachings. In view of the foregoing, this description should not be construed as limiting the invention.
Claims (10)
1. A method for determining a potential damage partition of a deep-buried fracture surrounding rock, comprising the steps of:
Sampling surrounding rock cracks of the engineering rock body, and determining surrounding rock crack information of each surrounding rock crack;
determining a plurality of target radius values according to the surrounding rock fracture information; the target radius value is the maximum radius value in all surrounding rock cracks in the same group;
Performing a surrounding rock fracture toughness test on the engineering rock mass to determine the surrounding rock fracture toughness;
Performing a rock mass stress field test on the engineering rock mass to determine an average stress field of the engineering rock mass;
determining a maximum stress intensity factor by utilizing a fracture mechanics formula according to the maximum radius value and the average stress field;
and determining potential damage subareas of the surrounding rock according to the maximum stress intensity factor and the fracture toughness of the surrounding rock.
2. The method of determining a potential damage partition of a deep-buried fracture surrounding rock of claim 1, wherein said determining a plurality of target radius values from each of said surrounding rock fracture information; the target radius value is the maximum radius value in all surrounding rock cracks in the same group, and specifically comprises the following steps:
Projecting the surrounding rock crack information on a Schmidt equal-area red flat projection network according to a normal line, and grouping the surrounding rock cracks according to a density value line of the Schmidt equal-area red flat projection network;
performing trace length conversion on the trace lines of the surrounding rock cracks in the same group, and determining the radius of the surrounding rock cracks;
And sequencing and regression analysis are carried out on the radii of the surrounding rock cracks in the same group, and the maximum radius value of each group of surrounding rock cracks is determined.
3. The method for determining the potential damage partition of the deep-buried fracture surrounding rock according to claim 1, wherein the step of performing a surrounding rock fracture toughness test on the engineering rock body to determine the surrounding rock fracture toughness specifically comprises the following steps:
Performing a center straight crack semicircular disc fracture toughness test on a test sample of the engineering rock body by using a rock mechanical testing machine, and determining I-type fracture toughness in the surrounding rock fracture toughness;
And carrying out a three-axis compression shear test on a test sample of the engineering rock mass by using a rock mechanical testing machine, and determining the type II fracture toughness in the fracture toughness of the surrounding rock.
4. The method of determining a potential failure zone of a deep-buried fracture surrounding rock according to claim 1, wherein the rock mass stress field test comprises a hydraulic fracturing method and a stress relief method.
5. The method for determining the potential damage partition of the deep-buried fracture surrounding rock according to claim 1, wherein the step of performing a rock mass stress field test on the engineering rock mass to determine the average stress field of the engineering rock mass specifically comprises the following steps:
performing a rock stress field test on the engineering rock mass to determine the normal stress and the shear stress of a fracture surface;
And determining an average stress field according to the positive stress and the shear stress.
6. The method for determining potential damage partitions of deep-buried fracture surrounding rock according to claim 3, wherein the determining potential damage partitions of surrounding rock according to the maximum stress intensity factor and the surrounding rock fracture toughness specifically comprises:
Judging whether the maximum stress intensity factor meets a first judging condition or whether the maximum stress intensity factor meets a second judging condition, and obtaining a first judging result; the first judgment condition is that the I-type stress intensity factor or the III-type stress intensity factor in the maximum stress intensity factors is larger than the I-type fracture toughness; the second judgment condition is that the type II stress intensity factor in the maximum stress intensity factors is larger than the type II fracture toughness;
If the first judgment result indicates that the maximum stress intensity factor meets the first judgment condition or the maximum stress intensity factor meets the second judgment condition, the fracture is determined to be damaged, and the surrounding rock fracture is a surrounding rock potential damage partition.
7. A system for determining a zone of potential damage to a deeply-buried fracture surrounding rock, comprising:
The sampling module is used for sampling surrounding rock cracks of the engineering rock body and determining surrounding rock crack information of each surrounding rock crack;
The maximum radius value determining module is used for determining a plurality of target radius values according to the surrounding rock fracture information; the target radius value is the maximum radius value in all surrounding rock cracks in the same group;
The surrounding rock fracture toughness testing module is used for testing the fracture toughness of the surrounding rock of the engineering rock body and determining the fracture toughness of the surrounding rock;
The rock mass stress field testing module is used for testing the rock mass stress field of the engineering rock mass and determining the average stress field of the engineering rock mass;
the maximum stress intensity factor determining module is used for determining a maximum stress intensity factor by utilizing a fracture mechanics formula according to the maximum radius value and the average stress field;
And the surrounding rock potential damage partition determining module is used for determining a surrounding rock potential damage partition according to the maximum stress intensity factor and the surrounding rock fracture toughness.
8. The system for determining the potential damage partition of the deep-buried fracture surrounding rock according to claim 7, wherein the maximum radius value determining module specifically comprises:
The projection and grouping unit is used for projecting the surrounding rock fracture information on a Schmidt equal-area red flat projection network according to a normal line, and grouping the surrounding rock fracture according to a density value line of the Schmidt equal-area red flat projection network;
the trace length conversion unit is used for performing trace length conversion on the trace lines of the surrounding rock cracks in the same group and determining the radius of the surrounding rock cracks;
And the sequencing and regression analysis unit is used for sequencing and regression analysis of the radii of the surrounding rock cracks in the same group and determining the maximum radius value of each group of surrounding rock cracks.
9. The system for determining the potential damage partition of a deep fracture surrounding rock according to claim 7, wherein the surrounding rock fracture toughness testing module specifically comprises:
the I-type fracture toughness determining unit is used for testing the fracture toughness of the center straight crack semicircular disc of the test sample of the engineering rock body by using a rock mechanical testing machine, and determining the I-type fracture toughness in the fracture toughness of the surrounding rock;
and the type II fracture toughness determining unit is used for carrying out a triaxial stamping shear test on the test sample of the engineering rock body by using a rock mechanical testing machine to determine the type II fracture toughness in the surrounding rock fracture toughness.
10. The system of claim 7, wherein the rock mass stress field test comprises a hydraulic fracturing method and a stress relief method.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US4152941A (en) * | 1978-05-08 | 1979-05-08 | Terra Tek, Inc. | Process for measuring the fracture toughness of rock under simulated down-hole stress conditions |
| CN107036907A (en) * | 2017-04-07 | 2017-08-11 | 北京科技大学 | A kind of fissure rock intensive analysis Forecasting Methodology |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4152941A (en) * | 1978-05-08 | 1979-05-08 | Terra Tek, Inc. | Process for measuring the fracture toughness of rock under simulated down-hole stress conditions |
| CN107036907A (en) * | 2017-04-07 | 2017-08-11 | 北京科技大学 | A kind of fissure rock intensive analysis Forecasting Methodology |
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