Development and Application of an Integrative Direct Shear
Apparatus for Multi-scale Rock Mass Discontinuity

Multistage direct shear tests have been performed on saturated and unsaturated specimens of a compacted glacial till. A conventional direct shear apparatus was modified in order to use the axis-translation technique for direct shear tests on unsaturated soils. The soil can be subjected to a wide range of matric suctions. The testing procedure and some typical results are presented. Nonlinearity in the failure envelope with respect to matric suction was observed. Suggestions are made as to how best to handle the nonlinearity from a practical engineering standpoint. Key words: shear strength, unsaturated soils, negative pore-water pressures, soil suction, direct shear.

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Research of the Permafrost Dynamic Load Direct Shear Apparatus

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.405-408.454 ◽

2013 ◽

Vol 405-408 ◽

pp. 454-459

Author(s):

Ying Hui Cui ◽

Jian Kun Liu ◽

Peng Lv

Keyword(s):

Numerical Simulation ◽

Power Systems ◽

Engineering Design ◽

Control Systems ◽

Dynamic Load ◽

Dynamic Parameters ◽

Direct Shear ◽

Direct Shear Apparatus ◽

And Control ◽

Measurement And Control

The dynamic parameters of the permafrost are very important for engineering design, also using in the numerical calculation. The dynamic parameters directly affect the correctness of engineering design and numerical simulation. Beijing Jiaotong University developed a novel dynamic load direct shear apparatus to measure these parameters. In the paper, it is analyzed Power systems, measurement and control systems of the dynamic load direct shear apparatus, and gave a verification experiment, the results show that dynamic load direct shear apparatus can complete its purpose.

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Study of Shear Constitutive Model for Schistose Rock Mass

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.838-841.800 ◽

2013 ◽

Vol 838-841 ◽

pp. 800-804

Author(s):

Shang Ge Liu ◽

Hua Xu ◽

Jian Liu ◽

Xiao Tao

Keyword(s):

Rock Mass ◽

Constitutive Model ◽

Engineering Practice ◽

Direct Shear ◽

Shear Tests ◽

Peak Displacement ◽

Direct Shear Tests ◽

Advantages And Disadvantages ◽

Piecewise Exponential ◽

Water Saturated

Based on the direct shear tests of schist and shale at dry and water-saturated states, combed with the advantages and disadvantages of models for rock mass and structure surface, we proposed shear stress-displacement constitutive model of schistose rock mass. The model is in the form of piecewise exponential function and its advantages are as follows: Piecewise function can reasonably describe the nonlinear pre-peak shear hardening and post-peak shear softening characteristics; Regard peak strength, peak displacement and residual strength as critical points, so it can accurately describe the strength characteristics of the material; The fitting degree is high with direct shear tests both at dry and water-saturated states; Only one parameter value is needed to obtain by fitting experimental curves while others are convenient to determine. All of those are benefit to applications in engineering practice.

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