邵阳地区不同压实度的膨胀土抗剪强度特性研究

Study on Shear Strength Characteristics of Expansive Soil under Different Compaction Degrees in Shaoyang Area

膨胀土路基的稳定性与其抗剪强度密切相关,通过直剪试验研究不同压实度膨胀土抗剪强度变化规律。试验结果表明,膨胀土粘聚力和内摩擦角均随压实度的增加而增加,近似线性变化。正应力和压实度与抗剪强度成正相关。对于相同的压实度,在正应力较小时表现为应变软化,正应力较大时表现为应变硬化。在确定抗剪强度设计值时,建议对于软化型曲线,其抗剪强度可取残余强度作为设计强度;对于硬化型曲线,可取曲线曲率明显变化点或剪切位移为1.0~1.5 mm对应的剪应力作为膨胀土抗剪强度设计值。

The stability of expansive soil subgrade is closely related to the shear strength. The variation rules of shear strength of expansive soil under different compaction degrees are studied by direct shear tests. The test results show that the cohesion and angle of internal friction of expansive soil increase approximately linearly with the increase of compaction degree. Compaction degree and vertical stress are positive correlation with shear strength. For the same degree of compaction, the curve of shear stress-strain is strain softening when the vertical stress is small, and the curve is strain harden while vertical stress is large. In determining the design value of shear strength, it is recommended to use residual strength as a design strength for strain softening curve, and use the shear stress value corresponding with signiifcant changes of curvature or shear displacement of 1.0~1.5 mm as shear strength design value for strain harden curve.