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A comparative study for determining rock joint normal stiffness with destructive uniaxial compression and nondestructive ultrasonic wave testing

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Journal of Rock Mechanics and Geotechnical Engineering 2023年第7期15卷 1700-1712页

作者： Zhenghu Zhang Jianbo Zhu Jianhui Deng School of Civil Engineering Dalian University of TechnologyDalian116024China Department of Civil and Environmental Engineering The Hong Kong Polytechnic UniversityHong KongChina Guangdong Provincial Key Laboratory of Deep Earth Sciences and Geothermal Energy Exploitation and Utilization College of Civil and Transportation EngineeringShenzhen UniversityShenzhen518060China State Key Laboratory of Hydraulics and Mountain River Engineering College of Water Resources and HydropowerSichuan UniversityChengdu610065China

Rock joints are one of the vital discontinuities in a natural rock *** to accurately and conveniently determine joint normal stiffness is therefore significant in rock ***,first,seven existing methods for determining joint normal stiffness were introduced and reviewed,among which MethodⅠ(the indirect measurement method),MethodⅡ(the direct determination method),MethodⅢ(the across-joint strain gauge measurement method)and MethodⅣ(the deformation measuring ring method)are via destructive uniaxial compression testing,while MethodⅤ(the best fitting method),MethodⅥ(the rapid evaluation method)and MethodⅦ(the effective modulus method)are through wave propagation principles and nondestructive ultrasonic ***,laboratory tests of intact and jointed sandstone specimens were conducted following the testing requirements and pro-cedures of those seven methods.A comparison among those methods was then *** results show that Method I,*** benchmark method,is reliable and ***Ⅱhas a conceptual drawback,and its accuracy is acceptable at only very low stress *** errors in the results from MethodⅢare very *** MethodⅣ,the testing results are sufficiently accurate despite the strict testing environment and complicated testing *** results from MethodⅤare greatly unstable and significantly dependent on the natural frequency of the *** joint normal stiffness determined with MethodⅥis stable and accurate,although data processing is ***Ⅶcould be adopted to determine the joint normal stiffness corresponding to the rock elastic deformation phase ***,it is suggested that MethodsⅠ,ⅣandⅥshould be adopted for the mea-surement of joint normal *** findings could be helpful in selecting an appropriate method to determine joint normal stiffness and,hence,to better solve discontinuous rock mass problems.

关键词： normal stiffness Rock joint Uniaxial compression Ultrasonic wave

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Modeling of Mechanical Behavior of Fractal Rock Joint

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International Journal of Minerals,Metallurgy and Materials 1999年第3期13卷 157-164页

作者： Jinan bang Marek A. Kwasniewski( Resources Engineering School. University of Science and Technology Beijing, Bejing 100083, China)( Rock Mechanics Laboratory, Faculty of Mining and Geology, Technical University of Silesia, Gliwice , Poland) Resources Engineering School University of Science and Technology Beijing Beijing 100083 China Rock Mechanics Laboratory Faculty of Mining and Geology Technical University of Silesia Gliwice Poland

The present study shows that naturally developed fracture surfaces in rocks display the properties of self-affine fractals. Surface roughness can be quantitatively characterized by fractal dimension D and the intercept A on the log-log plot of variance: the former describes the irregularity and the later is statistically analogues to the slopes of asperities. In order to confirm the effects of these fractalparameters on the properties and mechanical behavior of rock joints, which have been observed in experiments under both normal andshear loadings, a theoretic model of rock joint is proposed on the basis of contact mechanics. The shape of asperity at contact is assumed to have a sinusoidal form in its representative scale r, with fractal dimension D and the intercept A. The model considers different local contact mechanisms, such as elastic deformation, frictional sliding and tensile fracture of the asperity. The empirical evolution law of surface damage developed in experiment is implemented into the model to up-date geometry of asperity in loading history. The effects of surface roughness characterized by D, A and re on normal and shear deformation of rock joint have been elaborated.

关键词： fractal roughness mechanical behavior rock joints fractal dimension the intercept contact mechanics normal stiffness shear stiffness, surface damage

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Shear behaviour of anchored jointed rock mass under different engineering conditions considering damage and joint surface morphology

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Underground Space 2023年第6期13卷 316-334页

作者： Zenghui Zhao Wei Sun Shaojie Chen Hao Liu College of Energy and Mining Engineering Shandong University of Science and TechnologyQingdao 266590China State Key Laboratory of Strata Intelligent Control and Green Mining Co-founded by Shandong Province and the Ministry of Science and Technology Shandong University of Science and TechnologyQingdao 266590China Department of Petroleum Engineering China University of Petroleum-BeijingBeijing 102249China

According to different geological conditions and engineering disturbance,three dimensional numerical models of anchored jointed rock mass with two kinds of boundary conditions of constant normal load(CNL)and constant normal stiffness(CNS)were constructed considering the ductility damage of rockbolt,the stiffness degradation of grouting layer and the joint surface *** effects of anchorage angle,joint surface morphology,and boundary conditions on the shear performance of anchorage system were analyzed,and the failure characteristics under different working conditions were ***,the analytical solution of shear strength of anchored system was *** show that the larger the anchorage angle is,the more serious the necking phenomenon of rockbolt will *** damage degree of the bonding layer and the horizontal displacement of the bedding rock mass decrease with the increase of the joint surface *** CNL condition is to instantaneously apply high normal stress,and the CNS condition is to gradually form a high normal stress environment through the superposition of increment on the basis of the initial value,which can resist greater transverse *** is equivalent to enhancing the ductility of the *** shear strength of the system increases with the increase of normal stress and normal *** the normal stiffness will underestimate the shear strength.

关键词： Anchored jointed rock mass normal stress normal stiffness Progressive damage

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Propagation of plane waves in thermoelastic cubic crystal material with two relaxation times

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Applied Mathematics and Mechanics(English Edition) 2007年第5期28卷 627-641页

作者： Rajneesh Kumar Manjeet Singh Department of Mathematics Kurukshetra University Department of Mathematics S.U.S. Govt. College

A problem concerned with the reflection and refraction of thermoelastic plane waves at an imperfect interface between two generalized thermally conducting cubic crystal solid half-spaces of different elastic and thermal properties with two relaxation times has been investigated. The generalized thermoelastic theory with two relaxation times developed by Green and Lindsay has been used to study the problem. The expressions for the reflection and refraction coefficients which are the ratios of the amplitudes of reflected and refracted waves to the amplitude of incident waves are obtained for an imperfect boundary and deduced for normal stiffness, transverse stiffness, thermal contact conductance, slip and welded boundaries. Amplitude ratios of different reflected and refracted waves for different boundaries with angle of emergence have been compared graphically for different incident waves. It is observed that the amplitude ratios of reflected and refracted waves are affected by the stiffness and thermal properties of the media.

关键词： generalized thermoelasticity normal stiffness transverse stiffness thermal contact conductance cubic crystal amplitude ratios

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Fluid Flow Analysis on Sheared Rock Masses using the Discrete Fracture Network Method

Fluid Flow Analysis on Sheared Rock Masses using the Discret...

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作者： Larissa Kamseu 绍兴文理学院

学位级别：硕士

While shear flow behavior through fractured media has so far been studied at the scale of single fractures,we propose a numerical analysis on the effect of shearing deformation on the permeability and fluid flow patterns at the scale of fractured rock masses,using a twodimensional distinct element program based on a realistic discrete fracture network *** the assumption that the rock matrix is impermeable,linearly elastic and fluid flows only in fractures,we carried out several numerical experiments on three fracture network *** varying fracture densities(1.4,1.45 and 1.5),we calculated the changes in permeability of the stimulated shearing fractured rock mass under different criteria,and the influence of shear on the mechanical properties of the fracture *** included normal fracture stiffness variation,fracture densities,normal stress loading conditions,and permeability flow in both horizontal and vertical *** numerical experiments show that upon initiation of shear,the permeability increases or decreases,with contact asperities overriding each other,thereby leading to an increase in shear stress with the increasing shear displacement,which causes the change in the mechanical properties of the network and the reorientation of the fluid flow *** existence of different orientations of fractures and their connectivity in different stress states defines the possible behavior of *** change in permeability with maximum minimum flow rate of 1E-8 and 1E-9 respectively,are plotted against the shearing rate displacement of *** simulation results showed that,for flow in the horizontal direction,the shearing aperture during shearing greatly influenced the flow no matter the densities of the cracks present;and for flow in the vertical direction,the rate of shearing displacement and degree of dilation influenced the fluid *** the other hand,the varying fracture stiffness values changes in accordance to the surr

关键词： Permeability Fractured rock masses Shear Discrete Fracture Network (DFN) Coupled Hydro-mechanical Processes normal stiffness

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