CN1645101A - Determining method for mechanics quality stable threshold of rock structural face - Google Patents

Abstract

A method for confirming stable threshold includes preparing 10cm and 30cm test section on small size rock structural surface, measuring and calculating out necessary data, using JRC dimension effect fractal model to convert out JRC dimension effect fractal dimension D30, using JRC dimension effect rate formula f=(0.1Ln)-D30-(0.1Ln-1)-D30/2-D30-1 to carry out analysis of sampling length Ln to effect rate f for obtaining Ln-f relation chart, confirming that corresponding length of sampling on chart is the stable threshold when f=5% is taken on the chart.

Description

Mechanics quality stable threshold of rock structural face is determined method

(1) technical field

The present invention relates to mechanics quality stable threshold of rock structural face and determine method.

(2) background technology

Before the present invention makes, still there is not mechanics quality stable threshold of rock structural face to determine method at present.The rock mass discontinuity mechanical property has size effect character, owing to there is not mechanics quality stable threshold of rock structural face to determine method, the specimen size that can't solve the size effect reduction value of indoor mechanical property test findings, the test of on-the-spot mechanical property is determined and the problem such as choose of mechanical property empirical estimating length.

(3) summary of the invention

The objective of the invention is to solve owing to there is not mechanics quality stable threshold of rock structural face to determine method, and the specimen size that can't solve the test of the size effect reduction value of indoor mechanical property test findings, on-the-spot mechanical property is determined and the shortcoming of the problem such as choose of mechanical property empirical estimating length, provide a kind of principle simple, easy to operate, with low cost, result of use is good, is convenient to determine on the small scale structures face method of mechanics quality stable threshold of rock structural face.

Mechanics quality stable threshold of rock structural face of the present invention is determined method, comprises following sequential steps:

(1) on the small size rock mass discontinuity, corresponding required direction of measurement arranges that evenly statistics requisite number purpose length is respectively the survey section of 10cm and 30cm, adopts profilograph to draw the contour curve of above-mentioned survey section;

(2) measure the relief intensity R that above-mentioned 10cm surveys each contour curve of section _Y0, by formula $\mathrm{JR}{C}_0=49.2114e^{\frac{29}{450}}\arctan \left[\frac{{4R}_{y0}}{5}\right]$ Calculate each 10cm respectively and survey section roughness coefficient JRC ₀Value is surveyed the different roughness coefficient of section according to each 10cm and is calculated JRC ₀Expectation value E (JRC ₀);

(3) measure the relief intensity R that above-mentioned 30cm surveys each contour curve of section _Y30, by formula $\mathrm{JR}{C}_{30}=49.2114e^{\frac{29L_0}{450L_{30}}}\arctan \left[\frac{8R_{Y30}}{L_{30}}\right]$ Calculate each 30cm respectively and survey section roughness coefficient JRC ₃₀Value is surveyed the different roughness coefficient of section according to each 30cm and is calculated JRC ₃₀Expectation value E (JRC ₃₀);

(4) by JRC size effect fractal model $E\left({\mathrm{JRC}}_{30}\right)=E\left({\mathrm{JRC}}_0\right){\left[\frac{L_{30}}{L_0}\right]}^{{-D}_{30}},$ Conversion obtains rock mass discontinuity JRC size effect Fractal dimensions ₃₀

(5) the JRC size effect Fractal dimensions that step (4) is obtained ₃₀The relative JRC size effect of value substitution rate formula $f=\frac{{\left({0.1L}_n\right)}^{-D_{30}}-{({0.1L}_n-1)}^{{-D}_{30}}}{2^{-D_{30}}-1},$ Carry out sample length L _nSensitivity analysis with relative JRC size effect rate f obtains L _n-f graph of a relation, as shown in Figure 1.At L _nOn-f the graph of a relation, when getting f=5%, L _nSample length corresponding on the-f relation curve is rock structural plane roughness coefficient stable threshold L _n ^*

(6) the rock structural plane roughness coefficient stable threshold L that step (5) is determined _n ^*As mechanics quality stable threshold of rock structural face.

Employing the present invention have the following advantages: with mechanics quality stable threshold of rock structural face L _n ^*Foundation as the analysis of rock mass discontinuity mechanics quality stable, the specimen size of promptly carrying out the test of the size effect reduction value of the indoor mechanical property test findings of rock mass discontinuity, on-the-spot mechanical property is determined and during the choosing of mechanical property empirical estimating length, the sampling size of selected structural plane should be greater than L _n ^*, could guarantee that the estimation of stability that the stability and the reliability of mechanical property of structural plane, its result can directly apply to engineering rock mass calculates.Mechanics quality stable threshold of rock structural face determines that the method principle is simple, realize very easily owing to only need on the small size rock mass discontinuity, to carry out the statistical measurement of roughness coefficient, with low cost, result of use is good, be convenient to determine mechanics quality stable threshold of rock structural face, the specimen size that solves the test of the size effect reduction value of indoor mechanical property test findings, on-the-spot mechanical property determines and the problem such as choose of mechanical property empirical estimating length to have bigger implementary value and economic results in society.

(4) description of drawings

Fig. 1 is L _n-f graph of a relation

Fig. 2 is Xiao Langdi SSE group joint L _n-f relation curve

(5) embodiment

Studies show that the size effect of rock mass discontinuity mechanical property is mainly caused by the size effect of roughness coefficient, so can be with the rock structural plane roughness coefficient stable threshold as mechanics quality stable threshold of rock structural face.Diorite joint, Beishan Mountain sampling size is that the JRC statistical measurements of 10cm to 100cm is found, the JRC size effect fractal dimension (D of the different sampling sizes of same structural plane equidirectional _n) have a relative stability, D _nValue is around a certain eigenwert D _n ^*Fluctuation (is D up and down _n ^*-δ≤D _n≤ D _n ^*+ δ, δ are residual error, D _n ^*Represent sample length less than L _nThe JRC size effect fractal dimension eigenwert of scope inner structure face).Actual measurement statistics substitution JRC size effect fractal model with different sampling size roughness coefficients $D=-\frac{\lg \left[\frac{{\mathrm{JRC}}_n}{{\mathrm{JRC}}_0}\right]}{\lg \left[\frac{L_n}{L_0}\right]}$ Carry out the least square regression analysis and can ask for D _n ^*Value, be L with sampling size ₃₀=30cm roughness coefficient JRC ₃₀Actual measurement statistical value substitution JRC size effect fractal model $D_{30}=-\frac{\lg \left[\frac{{\mathrm{JRC}}_{30}}{{\mathrm{JRC}}_0}\right]}{\lg \left[\frac{L_{30}}{L_0}\right]}$ Can obtain D ₃₀Value, to J _1-1The D of 16 samples of joint four measuring direction _n ^*And D ₃₀Field data carries out statistical study opening relationships formula:

D _n ^*＝0.897D ₃₀????????????????????????????(1)

This character has determined to use small-scale structure surface roughness coefficient measurement result D ₃₀Analyze the stable threshold of large scale rock structural plane roughness coefficient, and then the stable threshold of definite rock mass discontinuity mechanical property; The result of study at diorite joint, the Beishan Mountain shows, at L _n≤ 10 ⁶In the scope of cm, JRC size effect fractal dimension eigenwert D _n ^*(can be by D ₃₀Expression) is subjected to sampling size L _nThe influence that changes is very responsive, this phenomenon explanation JRC size effect fractal dimension index (D ₃₀) determine that the roughness coefficient stable threshold has very high sensitivity.Above-mentioned two point discoveries have proved by D ₃₀Mensuration ask for the science and the rationality of roughness coefficient stable threshold, can be used for determining mechanics quality stable threshold of rock structural face.

Choose Xiaolangdi Dam Project wind and rain ditch west side slope rock mass SSE group joint, be respectively 10cm and the 30cm contour curve is tried to achieve JRC according to 387 sample lengths ₀, JRC ₃₀Statistical measures, and the D that converts by JRC size effect fractal model ₃₀Value the results are shown in table 1.According to table 1 data, draw calcareous packsand joint, clay-with-race rock joint on the strike direction and across strike direction L respectively _n-f relation curve, as shown in Figure 2.Can be obtained by Fig. 2, the roughness coefficient stable threshold L of direction is moved towards at calcareous packsand joint _n ^*Be 120cm, shown in Fig. 2 a, the roughness coefficient stable threshold L of calcareous packsand joint tendency direction _n ^*Be 110cm, shown in Fig. 2 b, the roughness coefficient stable threshold L of direction is moved towards at clay-with-race rock joint _n ^*Be 150cm, shown in Fig. 2 c, the roughness coefficient stable threshold L of clay-with-race rock joint tendency direction _n ^*Be 160cm, shown in Fig. 2 d.The roughness coefficient stable threshold at above-mentioned all directions joint is corresponding mechanics quality stable threshold of rock structural face.

Table 1 Xiao Langdi SSE group Joint Roughness Coefficient statistical measurements

Joint wall rock	Direction of measurement	????L n＝10cm		????L n＝30cm		??D 30
							Sample number	????JRC 0	Sample number	???JRC 30
		Calcareous packsand	Move towards direction	????35	????8.61						????34	??5.50	??0.4079
The tendency direction	????31					????12.12	????30	??7.43	??0.4454
			The clay-with-race rock	Move towards direction	????88					????15.83	????84	??11.86	??0.2628
The tendency direction	????82	????20.48				????77	??15.46	??0.2560

Claims (1)

1, a kind of mechanics quality stable threshold of rock structural face is determined method, it is characterized in that comprising following sequential steps:

(1) on the small size rock mass discontinuity, corresponding required direction of measurement arranges that evenly statistics requisite number purpose length is respectively the survey section of 10cm and 30cm, adopts profilograph to draw the contour curve of above-mentioned survey section;

(2) measure the relief intensity R that above-mentioned 10cm surveys each contour curve of section _Y0, by formula ${\mathrm{JRC}}_0=49.2114e^{\frac{29}{450}}\arctan \left[\frac{{4R}_{y0}}{5}\right]$ Calculate each 10cm respectively and survey section roughness coefficient JRC ₀Value,

Survey the different roughness coefficient of section according to each 10cm and calculate JRC ₀Expectation value E (JRC ₀);

(3) measure the relief intensity R that above-mentioned 30cm surveys each contour curve of section _Y30, by formula ${\mathrm{JRC}}_{30}=49.2114e^{\frac{29L_0}{450L_{30}}}\arctan \left[\frac{{8R}_{Y30}}{L_{30}}\right]$ Calculate each 30cm respectively and survey section roughness coefficient JRC ₃₀Value is surveyed the different roughness coefficient of section according to each 30cm and is calculated JRC ₃₀Expectation value E (JRC ₃₀);

(4) by JRC size effect fractal model $E\left({\mathrm{JRC}}_{30}\right)=E\left({\mathrm{JRC}}_0\right){\left[\frac{L_{30}}{L_0}\right]}^{-D_{30}},$ Conversion obtains rock mass discontinuity JRC size effect Fractal dimensions ₃₀

(5) the JRC size effect Fractal dimensions that step (4) is obtained ₃₀The relative JRC size effect of value substitution rate formula $f=\frac{{\left(0.1L_n\right)}^{-D_{30}}-{(0.1L_n-1)}^{-D_{30}}}{2^{-D_{30}}-1},$ Carry out sample length L _nSensitivity analysis with relative JRC size effect rate f obtains L _n-f graph of a relation is at L _nOn-f the graph of a relation, when getting f=5%, L _nSample length corresponding on the-f relation curve is rock structural plane roughness coefficient stable threshold L _n ^*(6) the rock structural plane roughness coefficient stable threshold L that step (5) is determined _n ^*As mechanics quality stable threshold of rock structural face.