Research On Microscopic Morphological Characteristics Of The Discontinuities On Point Cloud Data

Rock mass is a kind of geological body that has certain structure,and inside the rock mass,discontinuities with direction,size and shape are developed.The failure of rock mass usually does not occur through the part of intact material,but the weak structural plane within it.It can be said that the stability of rock mass is determined by the discontinuities,especially by the control ones.Three dimensional white scanner is applied to obtain the point cloud data of the discontinuities,this kind of data is mainly used to research on microscopic morphological characteristics of the discontinuities.Several research works isconducted as follows:(1)Description of rock discontinuities morphology is of great s significance to better understand the shear behavior of the discontinuities,so the new index(shear coefficient-SC)describing discontinuities morphology is proposed based on some key factors on shear behavior of its morphology in the shear direction.Shear coefficient SC describes undulation,distribution,height characteristics of discontinuities morphology in the shear direction,and can also characterizes directionality of the morphology.In addition,the relationship between SC and JRC(joint roughness coefficient)is also established based on 10 re-digitized JRC curve,which makes it more widely used.Then,with the help of three dimensional white scanner,the 3D digital triangular meshing model of rock discontinuities is based on point cloud data,and shear coefficient SC is extended to three-dimensional(3D)to better characterize 3D morphology characteristics of discontinuities.(2)3D white light scanner was utilized to obtain the structure surface point cloud data,and researched on the sampling spacing effect to describe the effect of morphology characteristics of the discontinuities.Findings of the study are as follows:with the increase of the sampling interval,gradient square Z2 and joint profile index RP decreases gradually,and attenuation of amplitude gradually increases,both with the sampling interval are opening down the quadratic function relation,the specific form for y=-ax2+bx+c a>0;with the increase of the sampling interval,the shear coefficient SC of the general trend is the decline,and both showed linear function fitting relationship.(3)3D scanning white light technology and 3D printing technology with production method of model specimens containing natural rock structure surface morphology is proposed.In order to validate the proposed containing natural structure model test method of casting whether meet the requirements,the placement of the model samples morphology and shear strength of the discrete are analyzed,and research has shown that this approach is in line with the requirements of the experimental.(4)With the help of three-dimensional white light scanners the natural rock specimens of A and B specimens were scanned and obtained their point cloud data.It is found that the discontinuities morphology does have anisotropic phenomena and characteristics of their anisotropic shape may only depending on its morphology characteristics;and put forward the use of shear coefficient variability to quantitatively describe the different anisotropy characteristics of different discontinuities.(5)By using the proposed containing the making methods of the natural structure of the interview,made several blocks containing the same natural structure of concrete specimens,and along different directions of shear tests to study the characteristics of the strength anisotropy.The study found that,the anisotropy of the peak shear strength with the increase of stress increases first and then decreases.Also based on the destruction of structure form surface,analyzes the relationship between morphology features of discontinuities anisotropy and strength anisotropy.