CN106198744A - A kind of Forecasting Methodology of bedded rock anisotropy uniaxial compressive strength - Google Patents

Abstract

The invention discloses the Forecasting Methodology of a kind of bedded rock anisotropy uniaxial compressive strength, include successively: be parallel to the direction of anisotropic surface drill through bedded rock experiment rock core；Along core column hoop direction, at a certain angle for SVEL on test azimuth 0, interval～90 ° of directions；The uniaxial compressive strength experiment value on test azimuth is calculated by SVEL；According to the anisotropic index in uniaxial compressive strength experiment value matching uniaxial compressive strength prediction type；The uniaxial compressive strength on anisotropic index prediction arbitrary orientation angle during minimum is taken by average absolute percentage percentage error.The present invention has simple to operate, the feature of low cost, it is provided that mathematical model can predict the anisotropy uniaxial compressive strength of bedded rock accurately, can be that Geotechnical Engineering stability analysis provides strong scientific basis in conjunction with means such as numerical analyses.

Description

A kind of Forecasting Methodology of bedded rock anisotropy uniaxial compressive strength

Technical field

The present invention relates to rock-soil mechanics field, be specifically related to the prediction of a kind of bedded rock anisotropy uniaxial compressive strength Method.

Background technology

Most of metamorphic rocks and the intensity of sedimentary rock and deformational behavior show obvious anisotropic character.By weak structure Face or the impact of anisotropic surface (sheet reason, layer reason and flow structure etc.), the intensity of experiment rock sample is relevant with loading direction.It is strong Degree maximum is usually located at 0 ° or 90 ° of azimuth (angle between maximum principal stress and anisotropic surface), and minimum of intensity It is usually located at azimuth 30～45 °.Typically anisotropic rock is considered as transversely isotropic medium, in anisotropy in theory On face, elastic property and intensive parameter are constant, and intensity gradually changes with azimuth on the direction intersected with plane of weakness.Determine rock The anisotropy uniaxial compressive strength of stone is typically obtained by uniaxial compression experiment test, but this needs to obtain in different orientations Experiment rock core, experiment rock core quantity is many, spend height, simultaneously can not predict the uniaxial compressive strength on arbitrary orientation angle.Therefore The present invention proposes the Forecasting Methodology of a kind of bedded rock anisotropy uniaxial compressive strength, utilizes the method, can reduce experiment consumption Material and testing expense, it was predicted that result is reasonable, and using value is bigger.

Summary of the invention

It is an object of the invention to: the Forecasting Methodology of a kind of bedded rock anisotropy uniaxial compressive strength, the method are provided Simple to operate, the anisotropy uniaxial compressive strength of measurable bedded rock, for the engineering stability evaluation in Geotechnical Engineering field Theory support and technical support is provided with risk assessment.

For reaching above-mentioned purpose, the present invention provides techniques below scheme:

The Forecasting Methodology of a kind of bedded rock anisotropy uniaxial compressive strength, it is characterised in that comprise the following steps:

(1) choose laminar formation experiment rock sample, be parallel to the direction of anisotropic surface drill through cylinder experiment rock core；

(2) direction taking anisotropic surface place is 0 ° of azimuth, along core column hoop direction, at a certain angle for interval Take N number of test point at azimuth 0～90 ° of directions, utilize the sound wave speed that interval transit time tester measures on this N number of azimuth respectively Degree；

(3) according to the uniaxial compressive strength on the N number of azimuth of below equation calculating:

${\mathrm{\σ}}_{c\mathrm{\β}}=3.67V_{p\mathrm{\β}}^{2.14}$

In formula: σ_cβFor the uniaxial compressive strength in azimuthal angle beta direction, V_pβFor the SVEL in azimuthal angle beta direction,

(4) according to the anisotropic index m of the following theoretical formula of uniaxial compressive strength matching on the N number of azimuth obtained And n:

In formula: σ_c0For the uniaxial compressive strength in 0 ° of direction, azimuth, σ_c90For the uniaxial compressive strength in 90 ° of directions, azimuth, σ_cminFor the minima of uniaxial compressive strength on each azimuth, θ is σ_cminThe azimuth at place.

Being averaged m and n value when absolute relative error percentage ratio AAREP value takes minimum is optimum prediction result, Jin Erke With the uniaxial compressive strength on prediction arbitrary orientation angle, AAREP computing formula is:

$AAREP=\frac{\mathrm{\Σ}\left|\frac{{\mathrm{\σ}}_{c,pred}-{\mathrm{\σ}}_{c,\exp }}{{\mathrm{\σ}}_{c,\exp }}\right|}{N}$

In formula: AAREP is mean absolute relative error percentage ratio, σ_c,predFor the uniaxial compressive predicted by theoretical formula Intensity, σ_c,expFor the uniaxial compressive strength determined by acoustic emission experiment.

It is an advantage of the current invention that: method and mathematical model that the present invention provides can predict each of bedded rock accurately Anisotropy uniaxial compressive strength, needs 1 piece little rock core cylinder simultaneously only, can be greatly saved test and expend, and has economy, operable Property the advantage such as strong, in conjunction with rock mass mechanics numerical simulation means, can be that engineering stability evaluation and the risk in Geotechnical Engineering field is commented Valency provides strong scientific basis.

Accompanying drawing explanation

Fig. 1 is the flow chart that the present invention predicts anisotropy uniaxial compressive strength；

Fig. 2 is that cylinder rock sample is cored direction schematic diagram；

Fig. 3 is SVEL test position point direction schematic diagram；

Fig. 4 is that SVEL is with azimuthal change；

Fig. 5 is that the uniaxial compressive strength of prediction is with azimuthal variation.

Detailed description of the invention

With specific embodiment, technical scheme is described in further detail below in conjunction with the accompanying drawings.

(1) certain laminar formation experiment rock sample is taken, by drilling through cylinder being parallel to the direction of anisotropic surface as shown in Figure 2 Experiment rock core, core diameter 2.54cm；

(2) according to the measurement direction shown in Fig. 3, along core column hoop direction, take on 7 azimuths with 15 ° for interval Test point, utilizes interval transit time tester to measure the sound on 0 °, 15 °, 30 °, 45 °, 60 °, 75 ° and 90 ° totally 7 azimuths respectively Wave velocity, result is shown in Fig. 4；

(3) according to the uniaxial compressive strength experimental result on 7 azimuths of below equation calculating:

${\mathrm{\σ}}_{c\mathrm{\β}}=3.67V_{p\mathrm{\β}}^{2.14}$

In formula: σ_cβFor the uniaxial compressive strength in azimuthal angle beta direction, V_pβSVEL for azimuthal angle beta direction；

(4) the uniaxial compressive strength following theoretical formula of experiment value matching on 7 azimuths that basis obtains is each to different Sex index m and n:

In formula: σ_c0For the uniaxial compressive strength in 0 ° of direction, azimuth, σ_c90For the uniaxial compressive strength in 90 ° of directions, azimuth, σ_cminFor the minima of uniaxial compressive strength on each azimuth, θ is σ_cminThe azimuth at place.

Working as m=1.1, during n=1.0, AAREP=0.52%, uniaxial strengeth experiment value and predictive value fitting effect are best, enter And the uniaxial compressive strength obtained on arbitrary orientation angle can be predicted, result is shown in Fig. 5, and this result can be further used for evaluating rock Geotechnique's journey domain engineering stability analysis and risk analysis.

The above, the specific embodiment that only present invention is the most feasible, protection scope of the present invention is not limited to this, any Those familiar with the art, in the technical scope of present disclosure, can become apparent to the letter of technical scheme Altered or equivalence are replaced and are each fallen within protection scope of the present invention.

Claims (2)

1. the Forecasting Methodology of a bedded rock anisotropy uniaxial compressive strength, it is characterised in that comprise the following steps:

(1) choose laminar formation experiment rock sample, be parallel to the direction of anisotropic surface drill through cylinder experiment rock core；

(2) direction taking anisotropic surface place is 0 ° of azimuth, along core column hoop direction, the side of being spaced at a certain angle Parallactic angle 0～90 ° of directions take N number of test point, utilize interval transit time tester to measure the SVEL on this N number of azimuth respectively；

(3) according to the uniaxial compressive strength on the N number of azimuth of below equation calculating:

${\mathrm{\σ}}_{c\mathrm{\β}}=3.67V_{p\mathrm{\β}}^{2.14}$

In formula: σ_cβFor the uniaxial compressive strength in azimuthal angle beta direction, V_pβSVEL for azimuthal angle beta direction；

(4) according to anisotropic index m and n of the following theoretical formula of uniaxial compressive strength matching on the N number of azimuth obtained:

In formula: σ_c0For the uniaxial compressive strength in 0 ° of direction, azimuth, σ_c90For the uniaxial compressive strength in 90 ° of directions, azimuth, σ_cmin For the minima of uniaxial compressive strength on each azimuth, θ is σ_cminThe azimuth at place.

2. the Forecasting Methodology of bedded rock anisotropy uniaxial compressive strength as claimed in claim 1, it is characterised in that described Anisotropic index m and n use below equation be fitted, take AAREP value minimum time m and n value be optimum prediction result:

$AAREP=\frac{\mathrm{\Σ}\left|\frac{{\mathrm{\σ}}_{c,pred}-{\mathrm{\σ}}_{c,\exp }}{{\mathrm{\σ}}_{c,\exp }}\right|}{N}$

In formula: AAREP is mean absolute relative error percentage ratio, σ_c,predFor the uniaxial compressive strength predicted by theoretical formula, σ_c,expFor the uniaxial compressive strength determined by acoustic emission experiment.