Constant volume ring shear specimen trimming and testing

The constant volume ring shear (CVRS) apparatus can use intact/undisturbed specimens to measure the peak and residual undrained shear strengths to estimate the post-peak strength reduction for seismic stability and permanent deformation analyses. A trimming apparatus and specimen container were fabricated to allow the trimming of an intact annular specimen directly into a container that is used for the shearing phase of the test. This article describes the specimen trimming, recommendations for handling and converting the trimming apparatus to the shearing container, which can be done either by hand or with a specially prepared trimmer holder, and suggestions for maintaining an undrained or constant volume shear condition. CVRS undrained peak and residual shear strengths for soils with different plasticity and clay size fractions are presented, and they are in agreement with peak undrained strength ratios from direct simple shear tests. This article also introduces correlations for peak and residual undrained shear strength ratios as a function of plasticity index for verification of future test results and planning level design.