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Direct shear test

About: Direct shear test is a research topic. Over the lifetime, 8932 publications have been published within this topic receiving 151091 citations.


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Journal ArticleDOI
01 Dec 1977
TL;DR: In this paper, the authors describe an empirical law of friction for rock joints, which can be used both for extrapolating and predicting shear strength data, and demonstrate that it can be estimated to within ± 1° for any one of the eight rock types investigated.
Abstract: The paper describes an empirical law of friction for rock joints which can be used both for extrapolating and predicting shear strength data. The equation is based on three index parameters; the joint roughness coefficientJRC, the joint wall compressive strengthJCS, and the residual friction angleφ r . All these index values can be measured in the laboratory. They can also be measured in the field. Index tests and subsequent shear box tests on more than 100 joint samples have demonstrated thatφ r can be estimated to within ± 1° for any one of the eight rock types investigated. The mean value of the peak shear strength angle (arctanτ/σ n ) for the same 100 joints was estimated to within 1/2°. The exceptionally close prediction of peak strength is made possible by performing self-weight (low stress) sliding tests on blocks with throughgoing joints. The total friction angle (arctanτ/σ n ) at which sliding occurs provides an estimate of the joint roughness coefficientJRC. The latter is constant over a range of effective normal stress of at least four orders of magnitude. However, it is found that bothJRC andJCS reduce with increasing joint length. Increasing the length of joint therefore reduces not only the peak shear strength, but also the peak dilation angle and the peak shear stiffness. These important scale effects can be predicted at a fraction of the cost of performing large scale in situ direct shear tests.

2,139 citations

Journal ArticleDOI
TL;DR: In this article, the deformation characteristics of rock joints under normal and shear loading were investigated by conducting loading/unloading and repeated load cycling tests on a wide variety of fresh and weathered joints in five different rock types.

1,490 citations

Journal ArticleDOI
TL;DR: In this paper, an empirical strength criterion for rocks and rock masses is proposed, which includes the uniaxial compressive strength of the intact rock material and introduces two dimensionless parameters, m and s.
Abstract: An empirical strength criterion for rocks and rock masses is proposed. The nonlinear criterion includes the uniaxial compressive strength of the intact rock material and introduces two dimensionless parameters, m and s. The parameter m varies with rock type, the angle of interblock or interparticle friction and the degree of block or particle interlock. The parameter s varies from 1.0 for intact rock material to zero for granular aggregates and depends on the interparticle tensile strength and the degree of interlock within the rock mass. For anisotropic rock, both m and s vary with the orientations of the planes of weakness to the principal stress directions. Approximate relationships between rock type, rock mass quality indices, and the rock mass strength parameters m and s, are presented. These relationships have been found useful in preliminary design calculations for slopes and underground excavations in jointed rock.

1,386 citations

Journal ArticleDOI
TL;DR: In this paper, the transition from a saturated soil to an unsaturated soil is described in terms of two independent stress state variables, i.e., the shear strength of unsaturated and saturated soil.
Abstract: The shear strength of an unsaturated soil is written in terms of two independent stress state variables. One form of the shear strength equation isThe transition from a saturated soil to an unsatur...

1,306 citations

Journal ArticleDOI
TL;DR: In this paper, the authors show that shear strength data from the research literature suggests that there is a nonlinear increase in the strength of unsaturated soils in the presence of saturated soils.
Abstract: Experimental studies on unsaturated soils are generally costly, time-consuming, and difficult to conduct. Shear strength data from the research literature suggests that there is a nonlinear increas...

1,302 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023261
2022519
2021539
2020525
2019463
2018478