CN106644680A - Quantitative classification method for rock sample crushing degree based on grid density and crack density - Google Patents

Abstract

A method for quantitatively classifying rock sample fragmentation degree based on grid density and crack density, the method comprising the following steps: Step 1: Obtain a crack development diagram; Step 2: Make a "360 grid"; Step 3: Draw a 360 grid density The relationship diagram of Γ _W segment and the corresponding number of rock samples; Step 4: According to the relationship diagram obtained in Steps 2 and 3, draw the relationship diagram between the number of cracks and the 360 grid density Γ _W ; Step 5: Establish a 360 grid density Γ _W describes the classification standard of rock sample fragmentation degree; Step 6: calculates the corresponding rock sample crack density Γ _J of each crack quantity counted in step 2; Step 7: establishes the description rock sample fragmentation degree with rock sample crack density Γ _J Classification standard; Step 8: Combine Γ _W and Γ _J to quantitatively classify the degree of rock sample fragmentation. The technical problem to be solved by the present invention is to provide a quantitative classification method of rock sample fracture degree based on grid density and crack density, which can meet the requirements of rock sample damage characteristics and quantitative analysis of fracture degree.

Description

A Quantitative Classification Method of Fragmentation Degree of Rock Samples Based on Grid Density and Crack Density

technical field

The invention relates to the field of rock mechanics tests in geotechnical engineering, in particular to a method for quantitatively classifying the fracture degree of rock samples based on grid density and crack density.

Background technique

Rock mechanics test is the basis of rock mechanics and one of the important means to study rock mechanics and engineering. Although scientific calculation and theoretical analysis have reached a considerable height, rock mechanics tests still play an irreplaceable role in directly solving mechanical problems in actual engineering. With the deepening of research, higher requirements are put forward for the analysis of test results. .

After the rock sample is subjected to uniaxial, triaxial and other mechanical tests, the rock sample will be damaged macroscopically, and several or even dozens of cracks will appear on the surface of the rock sample, and the corresponding rock sample will be decomposed into different sizes and irregular shapes. The failure characteristics and fragmentation degree of rock samples are closely related to the rock type and the stress path of loading and unloading. Exploring the failure mode of rock samples is of great significance for grasping the failure mechanism of rocks under various stress paths. It is one of the essential contents in the analysis of rock mechanical properties, so it is particularly important to judge the degree of fracture of rock samples accurately and quantitatively.

At present, in the literature, reports and books about the failure state of rock samples after mechanical tests, they are usually only qualitatively called "relatively broken", "broken", etc., and there is no quantitative index description for the development of cracks and the degree of breakage of rock samples. , the same or different types of rocks, or the failure state of rock samples with different loading and unloading stress paths cannot be quantitatively compared, which brings great difficulties to the description of rock mechanical properties.

Contents of the invention

The technical problem to be solved by the present invention is to provide a quantitative classification method of rock sample fracture degree based on grid density and crack density, which can meet the requirements of rock sample damage characteristics and quantitative analysis of fracture degree. The analysis process is simple and the value is accurate. The physical meaning is clear, the calculation result is intuitive, and it is convenient for practical operation.

In order to solve the above-mentioned technical problems, the technical solution adopted in the present invention is: a method for quantitatively classifying rock sample fragmentation degree based on grid density and crack density, the method comprising the following steps:

Step 1: Obtain the crack expansion diagram after the destruction of multiple rock samples of the same size;

Step 2: Make a "360 grid" of each rock sample, use the "360 grid" to count the number of cracks in each crack development diagram obtained in step 1, and draw a relationship diagram between the number of cracks and the number of corresponding rock samples;

Step 3: Use the "360 grid" to count the number Q _W of grids containing cracks in each crack development diagram obtained in step 1, and calculate the 360 grid density Γ _W of each rock sample with cracks. The calculation formula is

In the formula, Q _W is the number of grids containing cracks in each rock sample, 0 ≤ Q _w ≤ 360,

Draw the relationship diagram between the 360 grid density Γ _W segment and the corresponding number of rock samples;

Step 4: According to the relationship diagram obtained in steps 2 and 3, draw the relationship diagram between the number of cracks and the 360 grid density Γ _W , and analyze the relationship diagram to know that as the number of cracks increases, the 360 grid density is in the form of a power function When the number of cracks reaches more than 20, the growth trend of 360 grid density tends to be stable;

Step 5: According to the results of the statistical analysis in step 4, referring to the classification standards of the rock mass fragmentation degree index in the relevant codes of rock mechanics, combined with the actual fragmentation degree of the damaged rock sample and its 360 grid density value, establish a 360 grid density _ΓW to describe the rock mass. The classification criteria for the degree of sample fragmentation are as follows:

0≤Γ _W <0.1: slightly broken;

0.1≤Γ _W <0.3: relatively broken;

_0.3≤ΓW <0.5: Broken;

_0.5≤ΓW <0.8: very broken;

0.8≤Γ _W ≤1.0: completely broken;

Step 6: Calculate the rock sample crack density Γ _J corresponding to the number of cracks counted in step 2, the calculation formula is

In the formula, Q _J is the number of cracks; S is the lateral area of the rock sample, and K is the adjustment coefficient;

Step 7: According to the results of the statistical analysis in step 6, refer to the classification standard of the rock mass fracture degree index in the relevant codes of rock mechanics, and combine the actual fracture degree of the damaged rock sample and its crack density value, establish a description rock sample with the rock sample crack density Γ _J The classification criteria for the degree of fragmentation are as follows:

0≤Γ _J <0.3: loose cracks;

0.3≤Γ _J <0.5: Dense cracks;

0.5≤Γ _J <0.8: dense cracks;

0.8≤Γ _J <1.0: very dense cracks;

Γ _J ≥1.0: Fragmentation;

Step 8: Combining the classification standard established in step 5 to describe the degree of rock sample fragmentation with the 360 grid density Γ _W and the classification standard established in step 7 to describe the degree of rock sample fragmentation with the rock sample crack density Γ _J , the rock sample fragmentation Quantitative classification of degree, defined as follows:

(1) Relatively complete: 0≤Γ _W <0.1, 0≤Γ _J <0.5;

(2) Relatively broken: 0.1≤Γ _W <0.3, 0.5≤Γ _J <0.8;

(3) Broken: 0.3≤Γ _W <0.5, 0.8≤Γ _J <1.0;

(4) Very broken: 0.5≤Γ _W <0.8, Γ _J ≥1.0;

(5) Complete fragmentation: 0.8≤Γ _W ≤1.0, Γ _J ≥1.0.

In step 1, the crack development diagram of the rock sample after destruction is obtained through the "a rock sample crack drawing device and drawing method" disclosed in the patent No. 201410068603.5; crack development diagram.

In step 2, the "360 grid" is made by dividing the crack pattern obtained in step 1 into 10 grids in the height direction of the rock sample, and 36 grids in the perimeter direction of the rock sample, forming a total of 360 grids. A "360 grid" of grids.

In step 2, the crack number statistics method is as follows:

a. For cracks that appear alone, count directly according to the actual number of cracks;

b. For cracks with intersections or bifurcations in the middle, according to the extension direction of the controlling cracks damaged by the rock sample, the main controlling cracks are counted first, and then the secondary cracks that intersect or bifurcate with it are counted.

In step 3, the statistical method for the number of grids Q _W containing cracks is:

a. All cracks appearing in the grid are counted as 1;

b. When multiple cracks appear in the same grid at the same time, it is still counted as 1, that is, only the number of grids with cracks appears is counted, and the cracks in the grids are not repeatedly counted.

The calculation method of the adjustment coefficient K in step 6 is:

In the statistical process, it is found that the number of cracks in the damaged rock sample is about 20, and it has been completely broken. In order to facilitate the regular statistics of the crack density, the corresponding crack density when the number of cracks is 20 is defined as the standard 1, so the value of K is D is the rock sample diameter.

A method for quantitatively classifying rock sample fragmentation degree based on grid density and crack density provided by the present invention, on the basis of quantitative statistical analysis of the crack development degree and fragmentation degree on the surface of a large number of damaged rock samples, comprehensively considers the grid density of rock sample cracks and Based on the two parameters of crack density, a new quantitative classification method is proposed, which can meet the requirements of quantitative analysis of rock sample failure characteristics and fracture degree. The analysis process is simple, the value is accurate, the physical meaning is clear, the calculation result is intuitive, and it is convenient for practical operation.

Description of drawings

Below in conjunction with accompanying drawing and embodiment the present invention will be further described:

Fig. 1 is the expansion diagram of the rock sample crack that step 1 obtains in the embodiment of the present invention;

FIG. 2 is a schematic diagram of a "360 grid" made in Step 2 of Embodiment 1 of the present invention;

Fig. 3 is the "360 coordinate paper" mentioned in Step 2 of Embodiment 1 of the present invention that can be used to fix on the rock sample to facilitate statistics of the number of grids containing cracks;

Fig. 4 is the relationship diagram between the number of cracks and the number of corresponding rock samples drawn in Step 2 of Embodiment 1 of the present invention;

Fig. 5 is the relationship diagram of the 360 grid density Γ _W segment and the corresponding rock sample quantity drawn in step 3 of the embodiment of the present invention;

Fig. 6 is the relationship diagram between the number of cracks and the 360 grid density Γ _W drawn in Step 4 of Embodiment 1 of the present invention;

Fig. 7 is a schematic diagram of the degree of rock sample fragmentation corresponding to different 360 grid density Γ _W in Step 5 of Embodiment 1 of the present invention;

Fig. 8 is a schematic diagram of the rock sample fragmentation degree corresponding to different rock sample crack densities Γ _J in Step 7 of Embodiment 1 of the present invention;

Fig. 9 is the contrast chart that evaluates the standard that the present invention establishes in the embodiment of the present invention two, and this moment, rock sample fragmentation category is relatively complete;

Fig. 10 is the contrast diagram that evaluates the standard that the present invention establishes in the embodiment of the present invention two, and this moment, rock sample fragmentation category is more fragmentary;

Fig. 11 is the control diagram of evaluating the standard established by the present invention in the second embodiment of the present invention, at this time, the rock sample fragmentation category is broken;

Fig. 12 is a comparison chart for evaluating the standard established by the present invention in Example 2 of the present invention, at this time, the rock sample fragmentation category is very fragmented;

Fig. 13 is a comparison diagram for evaluating the standard established by the present invention in Example 2 of the present invention, and the rock sample fragmentation category at this time is completely fragmented.

detailed description

Embodiment one

A method for quantitatively classifying rock sample fragmentation degree based on grid density and crack density, the method comprises the following steps:

Step 1: Combining the literature data and a large number of sandstone, limestone, granite, sandstone, gneiss and other types of rocks completed in the laboratory in the early stage, the rock samples were destroyed under different loading and unloading stress paths, a total of 200 groups; 200 samples were obtained The crack development diagram of the rock sample of the same size after failure is shown in Fig. 1;

Step 2: Make a "360 grid" of each rock sample, and count the number of cracks in each crack development diagram obtained in step 1 through the "360 grid". Statistics are shown in Table 1:

Table 1 Statistical table of the number of cracks in rock samples

Draw the relationship diagram between the number of cracks and the number of corresponding rock samples, as shown in Figure 4;

Step 3: Count the number Q _W of grids containing cracks in each crack development diagram obtained in step 1 through the "360 grid",

Calculate the 360 grid density Γ _W of each rock sample with cracks, the calculation formula is

In the formula, QW is the number of grids containing cracks in each rock _sample , _0≤Qw≤360 , and the calculation results are shown in Table 2:

Table 2 360 grid density statistics table

Draw the relationship diagram of the 360 grid density Γ _W segment and the corresponding rock sample quantity, as shown in Figure 5;

Step 4: According to the relationship diagram obtained in steps 2 and 3, draw the relationship diagram between the number of cracks and the density Γ _W of the 360 grid, as shown in Figure 6, the analysis of the relationship diagram shows that: with the increase of the number of cracks, the 360 grid density The grid density increases in the form of a power function, and when the number of cracks reaches more than 20, the 360 grid density growth trend tends to be stable;

Step 5: According to the results of the statistical analysis in step 4, referring to the classification standards of the rock mass fragmentation degree index in the relevant codes of rock mechanics, combined with the actual fragmentation degree of the damaged rock sample and its 360 grid density value, establish a 360 grid density _ΓW to describe the rock mass. The classification criteria for the degree of sample fragmentation are as follows:

0≤Γ _W <0.1: slightly broken;

0.1≤Γ _W <0.3: relatively broken;

_0.3≤ΓW <0.5: Broken;

_0.5≤ΓW <0.8: very broken;

0.8≤Γ _W ≤1.0: completely broken;

The schematic diagram of rock sample fragmentation degree corresponding to different 360 grid density Γ _W is shown in Fig. 7;

Step 6: Calculate the rock sample crack density Γ _J corresponding to the number of cracks counted in step 2, the calculation formula is

In the formula, Q _J is the number of cracks, the unit is (bar), the unit is (bar/cm ² ); S is the rock sample lateral area, the unit is (cm ² ); K is the adjustment coefficient;

According to the statistical data in Table 1, the corresponding number of cracks is converted into crack density, as shown in Table 3:

Table 3 Statistical table of rock sample crack density

Step 7: According to the results of the statistical analysis in step 6, refer to the classification standard of the rock mass fracture degree index in the relevant codes of rock mechanics, and combine the actual fracture degree of the damaged rock sample and its crack density value, establish a description rock sample with the rock sample crack density Γ _J The classification criteria for the degree of fragmentation are as follows:

0≤Γ _J <0.3: loose cracks;

0.3≤Γ _J <0.5: Dense cracks;

0.5≤Γ _J <0.8: dense cracks;

0.8≤Γ _J <1.0: very dense cracks;

Γ _J ≥1.0: Fragmentation;

The schematic diagram of the degree of rock sample fracture corresponding to different rock sample crack densities Γ _J is shown in Figure 8;

Step 8: If only the 360 grid density or crack density of the rock sample is used for evaluation, there may be inaccurate aspects. For example, when the rock sample is dominated by penetrating long cracks, the crack density is small, and the grid density Larger, when there are many penetrating short and small cracks, the crack density is higher, but the grid density is smaller. In order to judge the rock sample fragmentation degree more accurately and comprehensively, the actual rock sample fragmentation degree is considered;

Combining the classification standard established in step 5 to describe the degree of rock sample fragmentation with the 360 grid density Γ _W and the classification standard established in step 7 to describe the degree of rock sample fragmentation with the rock sample crack density Γ _J , the comprehensive considerations are shown in Table 4 Show:

Table 4 Classification of rock sample fragmentation degree

(Note: When the grid density value and crack density value of the rock sample to be determined do not meet the endpoint value of the above classification, the nearest principle is selected.)

According to Table 4, the degree of rock sample fragmentation is quantitatively classified as follows:

(1) Relatively complete: 0≤Γ _W <0.1, 0≤Γ _J <0.5;

(2) Relatively broken: 0.1≤Γ _W <0.3, 0.5≤Γ _J <0.8;

(3) Broken: 0.3≤Γ _W <0.5, 0.8≤Γ _J <1.0;

(4) Very broken: 0.5≤Γ _W <0.8, Γ _J ≥1.0;

(5) Complete fragmentation: 0.8≤Γ _W ≤1.0, Γ _J ≥1.0.

In step 1, the crack development diagram of the rock sample after destruction is obtained through the "a rock sample crack drawing device and drawing method" disclosed in the patent No. 201410068603.5; crack development diagram.

In step 2, the method of making the "360 grid" is as follows: divide the crack pattern obtained in step 1 into 10 grids (with a distance of 1 cm) in the direction of the rock sample height, and divide it into 36 grids in the direction of the perimeter of the rock sample ( spacing 10°), forming a total of 360 grids of "360 grids", as shown in Figure 2;

The above "360 grid" can also be printed on a transparent plastic film of 15.7cm x 10cm (length x height), referred to as "360 coordinate paper". Make a circle around the damaged rock sample, cover it on the side of the rock sample and fix it, and count the number of cracks and grid density through manual counting. The schematic diagram of the "360 coordinate paper" is shown in Figure 3. In Figure 3, there are three Self-adhesive patch for fixing.

In step 2, the crack number statistics method is as follows:

a. For cracks that appear alone, count directly according to the actual number of cracks;

b. For cracks with intersections or bifurcations in the middle, according to the extension direction of the controlling cracks damaged by the rock sample, the main controlling cracks are counted first, and then the secondary cracks that intersect or bifurcate with it are counted.

In step 3, the statistical method for the number of grids Q _W containing cracks is:

a. All cracks appearing in the grid are counted as 1;

b. When multiple cracks appear in the same grid at the same time, it is still counted as 1, and the cracks in the grid are not counted repeatedly.

The calculation method of the adjustment coefficient K in step 6 is:

During the statistical process, it was found that when the number of cracks in the damaged rock sample was about 20, it was completely broken. In order to facilitate the regular statistics of crack density, the corresponding crack density was defined as 1 when the number of cracks was 20.

Therefore, the value of K is D is the diameter of the rock sample, in cm; for example, if the diameter of the rock sample is 5 cm, K is 2.5π.

Embodiment two

In order to verify the applicability and rationality of the classification method proposed by the present invention, a typical damaged rock sample is selected, and the rock sample fragmentation degree is calculated and evaluated according to the above method;

It can be seen from Fig. 9 that the 360 mesh density Γ _W is 0.08 (0<0.08<0.1), the crack density Γ _J is 0.2 (0<0.2<0.5), and the rock sample broken degree category: relatively complete.

It can be seen from Fig. 10 that the 360 mesh density Γ _W is 0.19 (0.1<0.19<0.3), the crack density Γ _J is 0.55 (0.5<0.55<0.8), and the rock sample fracture category: relatively broken.

It can be seen from Fig. 11 that the 360 grid density Γ _W is 0.42 (0.3<0.42<0.5), the crack density is Γ _J 0.95 (0.8<0.95<1.0), and the rock sample fracture category: Broken.

It can be seen from Fig. 12 that the 360 grid density Γ _W is 0.51 (0.5<0.51<0.8), the crack density Γ _J is 1.2 (1.2>1), and the rock sample fracture category: very broken.

It can be seen from Fig. 13 that the 360 mesh density Γ _W is 0.81 (0.8<0.81<1.0), the crack density Γ _J is 2.8 (2.8>1), and the rock sample fracture category is completely broken.

As can be seen from embodiment two, according to the 360 grid density and the crack density of rock sample cracks, the degree of fragmentation of rock samples can be quantitatively evaluated accurately, which can meet the requirements of rock sample failure characteristics and quantitative analysis of degree of fragmentation, and the analysis process is simple. The value is accurate, the physical meaning is clear, the calculation result is intuitive, and it is convenient for practical operation.

Claims (7)

1. it is a kind of based on mesh-density and the rock sample degree of crushing Quantitative Classification Method of crack density, it is characterised in that the method bag Include following steps：

Step 1：Obtain the crackle expanded view after the rock sample destruction of multiple same sizes；

Step 2：" 360 grid " of each rock sample is made, by each crackle expanded view that " 360 grid " is obtained to step 1 Crack number counted, draw the graph of a relation of crack number and corresponding rock sample quantity；

Step 3：By the number of grid Q containing crackle in each crackle expanded view that " 360 grid " is obtained to step 1_WUnited Meter, calculating each rock sample has 360 mesh-density Γ of crackle_W, computing formula is

In formula, Q_WFor the number of grid that each rock sample contains crackle, 0≤Q_W≤360。

Draw 360 mesh-density Γ_WIt is segmented the graph of a relation with corresponding rock sample quantity；

Step 4：According to the graph of a relation that step 2 and 3 are obtained, crack number and 360 mesh-density Γ are drawn_WGraph of a relation, to relation Figure is analyzed to be learnt：With the increase of crack number, 360 mesh-densities increase in power function form, reach in crack number When more than 20,360 mesh-density growth trends are intended to steadily；

Step 5：According to the result of step 4 statistical analysis, with reference to rock mechanics related specifications with regard to rock crushing level index point Class standard, the actual degree of crushing of decohesion rock sample and its 360 mesh-density values, set up with 360 mesh-density Γ_WDescription rock sample The criteria for classification of degree of crushing is as follows：

0≤Γ_W<0.1：It is slight broken；

0.1≤Γ_W<0.3：Relatively crush；

0.3≤Γ_W<0.5：It is broken；

0.5≤Γ_W<0.8：Crush very much；

0.8≤Γ_W≤1.0：Crush completely；

Step 6：The rock sample crack density Γ corresponding to each crack number counted in calculation procedure 2_J, computing formula is

${\mathrm{\&Gamma;}}_J=K\&CenterDot;\frac{Q_J}{S}$

In formula, Q_JFor crack number；S is rock sample lateral area, and K is regulation coefficient；

Step 7：According to the result of step 6 statistical analysis, with reference to rock mechanics related specifications with regard to rock crushing level index point Class standard, the actual degree of crushing of decohesion rock sample and its crack density value, set up and use rock sample crack density Γ_JDescription rock sample The criteria for classification of degree of crushing is as follows：

0≤Γ_J<0.3：Thin crackle；

0.3≤Γ_J<0.5：Closeer crackle；

0.5≤Γ_J<0.8：Intensive crackle；

0.8≤Γ_J<1.0：Very intensive crackle；

Γ_J≥1.0：Fragmentation；

Step 8：The mesh-density Γ of use 360 that step 5 is set up_WWhat the criteria for classification and step 7 of description rock sample degree of crushing was set up With rock sample crack density Γ_JThe criteria for classification of description rock sample degree of crushing combines, and to rock sample degree of crushing quantitative classification is carried out, It is defined as follows：

(1) it is more complete：0≤Γ_W<0.1,0≤Γ_J<0.5；

(2) relatively crush：0.1≤Γ_W<0.3,0.5≤Γ_J<0.8；

(3) crush：0.3≤Γ_W<0.5,0.8≤Γ_J<1.0；

(4) crush very much：0.5≤Γ_W<0.8, Γ_J≥1.0；

(5) fragmentation completely：0.8≤Γ_W≤ 1.0, Γ_J≥1.0。

2. a kind of rock sample degree of crushing quantitative classification for being based on 360 mesh-densities and crack density according to claim 1 Method, it is characterised in that：In step 1, by the way that " a kind of rock sample crackle is described disclosed in Patent No. 201410068603.5 Device and plotting method " obtains the crackle expanded view after rock sample destruction.

3. according to claim 1 a kind of based on mesh-density and the rock sample degree of crushing quantitative classification side of crack density Method, it is characterised in that：In step 1, the crackle exhibition after rock sample destruction can also be obtained by way of rock sample photofit Open figure.

4. according to claim 1 a kind of based on mesh-density and the rock sample degree of crushing quantitative classification side of crack density Method, it is characterised in that in step 2, the preparation method of " 360 grid " is：The crackle exhibition figure that step 1 is obtained is in rock sample height side 10 lattice are equally divided into upwards, in rock sample circumferential direction 36 lattice are equally divided into, formed " 360 grid " of totally 360 grids.

5. according to claim 1 a kind of based on mesh-density and the rock sample degree of crushing quantitative classification side of crack density Method, it is characterised in that in step 2, crack number statistical method is：

A, for the independent crackle for occurring, directly count according to actual bar number；

B, for having intersection or bifurcated in the middle of crackle, according to the controlling crack advance direction of rock sample destruction, first count main Controlling crackle, then count intersect therewith or bifurcated secondary crackle.

6. according to claim 1 a kind of based on mesh-density and the rock sample degree of crushing quantitative classification side of crack density Method, it is characterised in that in step 3, the number of grid Q containing crackle_WStatistical method be：

The crackle occurred in a, all grids is counted as 1；

B, same grid are still counted as 1 when there are many Cracks simultaneously, i.e., only statistics has the number of grid that crackle occurs, and does not weigh The crackle in grid is counted again.

7. according to claim 1 a kind of based on mesh-density and the rock sample degree of crushing quantitative classification side of crack density Method, it is characterised in that the regulation coefficient K computational methods of step 6 are：

Find in statistic processes, destruction rock sample crackle bar number is crushed completely when being 20 or so, close for the ease of crackle The regularization statistics of degree, it is standard 1 to define corresponding crack density when crack number is 20, therefore K values areD For rock sample diameter.