CN1815171A - Models in different shape of rack structural face shear strength size effect - Google Patents

Abstract

Present invention relates to a rock mass structure surface shearing strength size effect size effect fractal pattern. It includes following steps, calibrating test direction on selected structural surface, respectively selecting 10cm*10cm structural surface test samples according to selected test direction, proceeding structural surface test sample direct shear test, said direct shear test direction being concordance with calibrated test direction on structural surface test sample, obtaining five 10 cm*10 cm structural surface direct shear test shearing strength, calculating structural surface shear resistance statistics value to get rock mass structure surface shearing strength size effect size effect fractal pattern. Said invention can establish rock mass structure shearing strength size effect size effect rule with shearing strength size effect size effect according to direct shear test result.

Description

Models in different shape of rack structural face shear strength size effect

(1) technical field

The present invention relates to models in different shape of rack structural face shear strength size effect, be applicable to rock mass structure surface analysis with shearing strength size effect.

(2) background technology

Before the present invention makes, still do not set up models in different shape of rack structural face shear strength size effect at present according to the direct shear test result, be used to analyze the rock mass structural plane shearing strength size effect.During with the structural face shear strength of the joint straight shear test shearing strength evaluation engineering rock mass scale of laboratory size, normally give reduction by 70% coefficient artificially, it is very big that its reliability is influenced by human factor.

The structural plane model test findings shows that along with the increase of model area, structural plane average peak shear stress is nonlinear attenuation (Fig. 1).After model area was greater than certain value, average peak shear stress no longer was subjected to the influence of model area and reaches stationary value.Structural face shear strength shown in Figure 1 increases the rule that reduces with size and can be summarized as:

${\mathrm{\τ}}_n={\mathrm{\τ}}_{10}{\left[\frac{L_n}{L_{10}}\right]}^{-D}---\left(1\right)$

In the formula, L ₁₀Be laboratory dimensional structure face length degree (10cm), L _nBe the length (cm) of practical structures face, τ ₁₀Be the peak shear strength of laboratory dimensional structure face, τ _nPeak shear strength for the practical structures face.D is a structural face shear strength size effect fractal dimension, and it has been described shearing strength and has increased the rate of decay that reduces with the structural plane size, and promptly the D value is big more, and it is fast more to illustrate that shearing strength increases the rate of decay that reduces with the structural plane size; Be that the D value is more little, it is slow more to illustrate that shearing strength increases the rate of decay that reduces with the structural plane size.

(3) summary of the invention

The objective of the invention is to solve at present and do not set up models in different shape of rack structural face shear strength size effect according to the direct shear test result, be used to analyze the shortcoming of rock mass structural plane shearing strength size effect, provide a kind of principle simple, easy to operate, with low cost, result of use is good, is convenient to carry out the models in different shape of rack structural face shear strength size effect of rock mass structural plane shearing strength Analysis of Size Effect.

For this reason, the present invention is by the following technical solutions:

A kind of models in different shape of rack structural face shear strength size effect comprises following sequential steps:

(1) rating test direction on selected structural plane;

(2) according to selected test direction, choose the direct shear test that five structural fece samples that are of a size of 10cm * 10cm carry out structural fece sample, described direct shear test direction is consistent with rating test direction on the structural fece sample, tries to achieve five joint straight shear test shearing strength τ that are of a size of 10cm * 10cm _10i

(3) according to the direct shear test result, according to ${{\mathrm{\τ}}_{10}}^{*}=\underset{i=1}{\overset{5}{\mathrm{\Σ}}}{\mathrm{\τ}}_{10i}$ Driven dimension is the structural face shear strength statistical value τ of 10cm * 10cm ₁₀ ^*

(4) with τ ₁₀ ^*The substitution formula ${\mathrm{\τ}}_n={\mathrm{\τ}}_{10}{\left[\frac{L_n}{L_{10}}\right]}^{-D},$ Promptly obtain the rock mass structural plane shearing strength size effect

Fractal model: ${\mathrm{\τ}}_n={{\mathrm{\τ}}_{10}}^{*}\·{\left[\frac{L_n}{10}\right]}^{-D}---\left(2\right),$ D is known rock mass discontinuity shearing resistance in the formula

Size Effect of Strength fractal dimension, L herein ₁₀Call by value be 10.

The present invention compared with prior art, the models in different shape of rack structural face shear strength size effect principle is simple, easy to operate, with low cost, result of use is good, be convenient to set up rock mass structural plane shearing strength size effect rule, have bigger implementary value and economic results in society with shearing strength size effect according to the direct shear test result.

(4) description of drawings

Fig. 1 is a structural plane average peak curve map.

(5) embodiment

Table 1 has been listed day five 10cm of a waste level ground hydroenergy storage station grouan NW group structural plane * 10cm direct shear test sample direct shear test shearing strength value τ _10i, according to ${{\mathrm{\τ}}_{10}}^{*}=\underset{i=1}{\overset{5}{\mathrm{\Σ}}}{\mathrm{\τ}}_{10i}$ Driven dimension is the structural face shear strength statistical value τ of 10cm * 10cm ₁₀ ^*Get τ by table 1 data ₁₀ ^*=1.15MPa, substitution formula (2) promptly get a day waste level ground hydroenergy storage station grouan NW group structural face shear strength size effect fractal model:

${\mathrm{\τ}}_n=1.15\×{\left[\frac{L_n}{10}\right]}^{-D}---\left(3\right)$

Table 1 day waste level ground hydroenergy storage station grouan NW group joint straight shear test value

Specimen coding	τ 10i
		1	1.31
2	1.20
		3	1.13
4	1.08
		5	1.03

Claims (1)

1, a kind of models in different shape of rack structural face shear strength size effect is characterized in that comprising following sequential steps:

(1) rating test direction on selected structural plane;

(2) according to selected test direction, choose the direct shear test that five structural fece samples that are of a size of 10cm * 10cm carry out structural fece sample, described direct shear test direction is consistent with rating test direction on the structural fece sample, tries to achieve five joint straight shear test shearing strength τ that are of a size of 10cm * 10cm _10i

(3) according to the direct shear test result, according to ${{\mathrm{\τ}}_{10}}^{*}=\underset{i=1}{\overset{5}{\mathrm{\Σ}}}{\mathrm{\τ}}_{10i}$ Driven dimension is the structural face shear strength statistical value τ of 10cm * 10cm ₁₀ ^*

(4) with τ ₁₀ ^*The substitution formula ${\mathrm{\τ}}_n={\mathrm{\τ}}_{10}{\left[\frac{L_n}{L_{10}}\right]}^{-D},$ Promptly obtain models in different shape of rack structural face shear strength size effect: ${\mathrm{\τ}}_n={{\mathrm{\τ}}_{10}}^{*}\·{\left[\frac{L_n}{10}\right]}^{-D},$ D is known rock mass structural plane shearing strength size effect fractal dimension in the formula.