不同剪切速率对风化砂改良膨胀土抗剪强度指标的影响

The Impacts of Different Shear Rate on the Anti-Shear Strength Index of Weathering Improved Expansive Soil

土的抗剪强度指标受含水率、剪切速率以及土样的类别等多个因素的影响。为了研究不同剪切速率对风化砂改良膨胀土的抗剪强度指标的影响规律,分别在2.4,0.8 mm/min剪切速率下对不同含水率和不同掺砂比例的风化砂改良膨胀土样进行了室内直剪试验,得到了不同剪切速率下改良膨胀土的抗剪强度指标值。试验表明:采用2.4 mm/min的剪切速率测得的抗剪强度指标比采用0.8 mm/min的剪切速率测得的值要大;通过对比试验数据可知,剪切速率对内摩擦角的影响比对黏聚力的影响相对来说较小,对砂土的抗剪强度指标的影响比对黏土的抗剪强度指标要小,对含水率较小的土样的抗剪强度指标的影响比对含水率大的土样的抗剪强度指标要大。对于风化砂改良膨胀土的抗剪强度指标的测定时的剪切速率应采用规范要求的0.8 mm/min。

Antishear strength index of soil is influenced by moisture content, shear rate, soil samples cate gory, etc. In order to reveal the influence rules of different shear rate impacts on the antishear strength index of weathering sand improved expansive soil, direct shear test to the weathering sand improved ex pansive soil samples containing different moisture content and sanding proportion was executed under two shear rates （2.4 mm/min and 0.8 mm/min） condition in the laboratory. The results showed that the anti shear strength index under 2.4 mm/min shear rate was higher than the index under 0.8 mm/min shear rate. By comparing the test data, it was noticeable that the impact of shearing rate on the internal friction angle is relatively smaller than the impact on cohesion force, the impact on antishearing strength index of sandy soil is smaller than the impact on clay, and the impact on antishearing strength index of less mois ture content soil is larger than on the higher moisture content soil. Standard requirement of 0.8 ram/rain shear rate should be used on testing the antishear strength index of weathering sand improved expansive soil.