风化花岗片麻岩砂类土抗剪强度参数预估模型

Prediction models of shear strength parameters for sandy soil of weathered granite gneiss

【目的】分析风化花岗片麻岩砂类土非饱和抗剪强度随含水率和压实度的变化规律。【方法】以皖西大别山区典型风化花岗片麻岩砂土填料为研究对象,采用静压成型法制备该砂类土20种不同含水率和压实度组合状态的非饱和试样,通过室内大型直剪试验分析含水率和压实度对其抗剪强度参数的影响,回归建立相应的综合关系模型,并验证其预估精度。【结果】在相同压实度下,土样黏聚力和内摩擦角分别与含水率比值(含水率与最佳含水率之比)成显著的单峰左偏态高斯型函数关系和幂函数负相关性;在相同含水率下,黏聚力和内摩擦角均与压实度成显著的对数函数正相关关系;所建立的抗剪强度参数与含水率、压实度之间的综合关系模型具有较高的预估精度。【结论】预估模型可用于预测该砂类土的似黏聚力强度特性,并可供同类土体强度参数建模参考。

[Purposes]The variation law of unsaturated shear strength with water content and compaction degree was analyzed in sandy soil of weathered granite gneiss.[Methods]Taking the typical weathered granite gneiss sandy soil filler from the western Dabie Mountains in Anhui as the research object,non-saturated samples of this sandy soil in 20 different combinations of water content and compaction degree were prepared using the static pressure molding method.The influence of current water content and compaction degree on its shear strength parameters was analyzed through large-scale indoor direct shear tests.The corresponding comprehensive correlation models were established by regression,and their prediction accuracy was verified.[Findings]Under the same compaction degree,the cohesion and the internal friction angle of soil samples have significant unimodal left-skewed Gaussian function correlation and a power function negative correlation with the water content ratio(ratio of water content to optimum water content),respectively.Under the same water content,both of the cohesion and the internal friction angle have significant logarithmic function positive correlation with the compaction degree.The established comprehensive correlation models of cohesion as well as internal friction angle with water content and compaction degree are higher in prediction accuracy.[Conclusions]The prediction models can be used to predict the pseudo-cohesion strength characteristics for the compacted sandy soil,providing reference for the strength parameter modeling of similar soil.