非饱和黏性土抗剪强度的温度效应试验研究

为了系统地了解温度对黏性土工程性质的影响,本文采用南京地区三种不同矿物成分的黏性土,制成不同含水量和干密度的试样,在5~45℃条件下,开展了抗剪强度试验,获得了三种土的非饱和重塑试样的抗剪强度与温度的关系。试验结果表明:黏性土的黏聚力随温度升高呈线性变化; 亲水矿物含量较高的黏性土抗剪强度对温度变化较敏感,黏聚力随着温度的升高而降低,表现为强度的热软化现象; 亲水矿物含量较低的黏性土,当含水量较低(w≤17%)时,表现为强度的热硬化现象,当含水量较高(w≥22%)时,表现为强度的热软化现象,且干密度越高的试样,强度的温度效应越明显。论文还分析了非饱和黏性土抗剪强度的热硬化和热软化的内在机理。

DIRECT SHEAR TEST FOR TEMPERATURE EFFECT ON SHEAR STRENGTH OF UNSATURATED CLAYEY SOILS

In order to systematically study the temperature effect on the engineering properties of clayey soils,laboratory test was conducted to evaluate the relations between temperature and shear strength of unsaturated remodeling soil samples.Among three common types of clayey soils in Nanjing with different mineral composition,direct shear tests of soil samples in different moisture content and dry density have been done in the range of 5~50℃.The results indicate that the following. (1)the cohesive force change mainly and linearly with the temperature. (2) the shear strength of clayey soils with higher content of hydrophilic mineral is more sensitive to temperature change. (3)the cohesive force decrease with the temperature rise,showing thermal-softening on strength. (4) for clayey soils with lower content of hydrophilic mineral,when the moisture content is lower(w≤17%),the shear strength shows the thermo-hardening phenomenon,however it shows the thermal-softening phenomenon when the moisture content is higher(w≥22%),and the temperature effect on shear strength is more obvious when the dry density of sample is higher.Moreover,the mechanism of thermal softening and hardening of unsaturated clayey soils is analyzed.