粘土永久变形预估模型试验与仿真研究

路基永久变形影响沥青路面的车辙,经详细分析推荐出路基土永久变形试验方案,对粘土进行了重复加载动三轴试验,建立了塑性应变和荷载作用次数之间的关系式,使用最小二乘法拟合出该式中的系数与含水量和回弹模量之间的回归公式.采用扩展的Drunker-prager土体本构模型,对于粘土重复加载动三轴试验进行了有限元仿真.试验曲线或有限元仿真曲线与预估模型均比较吻合,相关系数R2均在0.99以上;模型参数的回归公式的相关系数R2最小值为0.53,大于临界值0.50.分析结果表明:建立的粘土永久变形预估模型可靠性较高,可以用有限元仿真来代替部分室内重复加载动三轴试验.

Study on the permanent deformation prediction model of clay through tests and simulations

The permanent deformation of subgrade has effects on the rutting of asphalt pavement. The program of permanent deformation tests of subgrade soils was established through analysis in detail. Repeated loads tests were conducted with clay. The basic relationship between the permanent strain and the number of load applications was found, and the regression formula between the coefficients in the models and a moisture content and a resilient modulus were found with the least square method. At last, extended Drunker-Prager model was used to clay and the repeated load triaxial tests were simulated by the finite element method. The square of the correlative coefficient between the calculated curve and measured or numerical simulated one was as great as 0.99. The minimum square of the correlative coefficient of the regression formula of the coefficients in the models was 0.53 which was greater than the critical value of 0.50. Results show that the permanent deformation prediction model for a clay founded have high reliability, and some repeated load triaxial tests can be replaced by finite element simulations.