土-水特征曲线预测非饱和土的抗剪强度对比研究

CONTRAST STUDY ON FORECAST OF SHEAR STRENGTH OF UNSATURATED SOIL USING SOIL WATER CHARACTERISTIC CURVE

目前,非饱和土的工程性质已成为岩土工程界研究的热点问题,而非饱和土的抗剪强度的研究对土的工程性质尤为重要。笔者总结了4种用土-水特征曲线预测非饱和土的抗剪强度的公式,用5个Bar的压力板仪测得了马家沟Ⅰ号滑坡体上土体的土-水特征曲线,并采用MATLAB软件,利用Van Genuchten模型对试验数据进行拟合;用国际先进的GDS非饱和反压剪切仪对控制基质吸力为50kPa和100kPa的非饱和土进行直剪试验,得到了相应的抗剪强度。用土-水特征曲线对非饱和土抗剪强度的4种预测值与试验结果进行对比分析,验证各预测公式的准确性,总结其优缺点。最后得出Fredlund预测公式的准确性最高,黄润秋预测公式最为简单易行。

At present, the engineering properties of unsaturated soil have become a hot topic in the geotechnical engineering field. The shear strength of unsaturated soil is particularly important for the engineering properties of soil. The authors have summarized four formulas which can forecast the shear strength of unsaturated soil using the soil water characteristic curve. The soil water characteristic curve of Majiagou Landslide ~ is obtained with the five bar pressure plate instrument. The MATLAB software and Van Genuchten model are used to fit the test data. The international advanced GDS unsaturated back pressure shear apparatus（UBPS） is used to proceed the direct shear tests on the unsaturated soil. The matric suction is controlled to be 50kPa and 100kPa. The relevant shear strength is obtained. Besides, the four predicted values of soil water characteristic curve and the test result are compared. The veracity of the predictor formulas is verified. Their merits and demerits are summarized. Finally, the Fredlund＇s prediction formula is the most accurate one and the Huang-Runqiu＇s formula is the most simple and practicable.