粗粒料的切线模量表达式与参数确定方法

运用两座250 m级高土石坝的实测沉降资料与有限元计算结果，分析了高土石坝的应变量级与应力水平，在此基础上分析了双曲线应力应变模型及其参数确定方法的合理性。研究表明，250 m级高土石坝竖直向应变量级可以达到5%，故常规三轴试验可以适应变形预测对应变范围的要求，但坝内应力水平普遍较低，与确定参数所用的高应力水平段试验数据不协调，从而给土石坝应力变形计算带来不确定性。为更充分地运用低应力水平时的试验结果，建议了应力应变数据的多项式拟合方法，提出一个新的切线模量表达式。对比研究表明，双曲线模型及其参数确定方法高估了等向压缩应力状态下粗粒料的初始切线模量；低估了剪切应力状态下粗粒料的切线模量。文中所提出的表达式可以更好地与应力应变试验结果相吻合，且参数的不确定性大为降低，为提高土石坝应力变形计算的可靠性奠定了基础。

A tangential modulus model for coarse granular materials and the corresponding method for parameter identification

The strain magnitude and the stress level in high earth and rockfill dams were studied based on the field settlement data and the corresponding finite element simulation results of two typical dams with heights of about 250 m. The reasonability of the widely used hyperbolic model and its parameter identification method were analyzed. It is found that the shear strain in 250 m high earth and rockfill dams can achieve a magnitude of 5%, and triaxial experiments can be satisfactorily used in deformation prediction. However, the stress level in dams is generally lower than those segments of experimental data used for parameter determination, which adds considerable uncertainty to stress and deformation analysis. To use the experimental data at low stress level fully, a polynomial method is suggested to fit the stress stain data and a new tangential modulus model is proposed. It is found that the initial loading modulus under an isotropic stress state is overestimated by the hyperbolic model, while the tangential modulus under a shear stress state is underestimated. The newly proposed model can fit the experimental data better and the degree of uncertainty in the calibrated parameters is considerably reduced, which lays a foundation for improving the reliability of stress and deformation analysis for high earth and rockfill dams.