Triaxial shear behavior of a cement-treated sandegravel mixture

A number of parameters, e.g. cement content, cement type, relative density, and grain size distribution,can influence the mechanical behaviors of cemented soils. In the present study, a series of conventionaltriaxial compression tests were conducted on a cemented poorly graded sandegravel mixture containing30% gravel and 70% sand in both consolidated drained and undrained conditions. Portland cement usedas the cementing agent was added to the soil at 0%, 1%, 2%, and 3% （dry weight） of sandegravel mixture.Samples were prepared at 70% relative density and tested at confining pressures of 50 kPa, 100 kPa, and150 kPa. Comparison of the results with other studies on well graded gravely sands indicated moredilation or negative pore pressure in poorly graded samples. Undrained failure envelopes determinedusing zero Skempton抯 pore pressure coefficient 餉 ？0？criterion were consistent with the drained ones.Energy absorption potential was higher in drained condition than undrained condition, suggesting thatmore energy was required to induce deformation in cemented soil under drained state. Energy absorptionincreased with increase in cement content under both drained and undrained conditions.
2014 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting byElsevier B.V. All rights reserved.     

Effects of temperature on the shear strength of saturated sand

The effect of temperature on the shearing response of saturated, dense sand was investigated using a series of temperature-controlled, isotropically-consolidated, hollow cylinder triaxial compression tests, where specimens were heated in drained conditions followed by shearing in undrained conditions. As expected, the deviatoric stress at the peak state (i.e., the undrained shear strength) was observed to increase with increasing initial mean effective stress. However, it was observed to decrease linearly with increasing temperature. The effects of temperature on the deviatoric stress at the peak state were attributed to a linear increase in the magnitude of negative shear-induced pore water pressure at the peak state with temperature. The relationship between the undrained shear strength and the pore water pressure with changes in temperature was represented well by linear equations. When the shear strength was interpreted in terms of the critical state, no obvious changes in the critical state line in the $p^{\prime }-q$ plane were observed, and the critical state friction angle was unaffected by temperature. During drained heating, the dense sand specimens were observed to expand volumetrically, causing the normal consolidation line in the $e-{\left(p^{\prime }/p_{\text{a}}\right)}^{0.5}$ plane to shift upward with increasing temperature without a change in the slope. The negative pore water pressure during undrained shearing caused the state paths of the dense sand specimens to move to the right. As the magnitude of negative pore water pressure increased with increasing temperature, no obvious effects on the critical state line in the $e-{\left(p^{\prime }/p_{\text{a}}\right)}^{0.5}$ plane were observed.