胶凝粗粒料的弹塑性模型与应用研究

目前工程技术人员对胶凝粗粒料能否应用于高堆石坝等重要、永久性建筑物还存在疑虑,这主要是由于目前对胶凝粗粒料力学性质研究尚不充分。尚没有广为认可的胶凝粗粒料标准本构模型,使得胶凝粗粒料数值模拟结果可信度较低。进行了胶凝砂砾料大围压范围(7级围压,范围100～3000 kPa)的室内三轴剪切试验,试验结果表明,胶凝砂砾料力学性质具有压硬性、强度非线性、强剪胀性和应变软化性等显著特征。研究发现,三轴应力路径的胶凝砂砾料应力应变关系可用驼峰曲线较好描述,其体积剪胀性可采用Rowe剪胀方程描述,以此建立了三轴应力平面内胶凝砂砾料应力应变关系,并根据广义塑性理论中切线模量与塑性模量之间的关系,将模型拓展至三维应力空间,得到了胶凝砂砾料弹塑性本构模型。试验结果和前人多组试验结果对该模型进行了验证,均表明模型具有良好的适用性,模型简明、实用,易于数值实现。将该模型成功应用于一个高面板坝的"胶凝增模区"弹塑性分析,并从坝体、防渗体应力变形安全性方面评估了胶凝料用于高堆石坝"增模"的可行性。

Elastoplastic model for cemented coarse-grained materials and its application

Until now, the engineers still doubt about whether the cemented coarse-grained soils can be used in permanent structures such as high rockfill dams. It is mainly due to the fact that the studies on the mechanical properties of the cemented coarse-grained soils are insufficient. At present, there is no widely accepted standard constitutive model for the cemented coarse-grained soils, so that the reliability of numerical simulation is greatly reduced. The indoor triaxial shear tests on cemented gravels are conducted under a large confining pressure range (7 confining pressures ranging from 100 to 3000 kPa). The test results show that the mechanical properties of the cemented gravels vary with different confining pressures. The nonlinear strength, dilatancy and strain softening can also be observed. It is found that the stress-strain relationship in triaxial stress paths can be described by the hump curve, and the dilatancy can be described by the Rowe’s dilatancy equation. Based on the relationship between the tangent modulus and the plastic modulus in the generalized plasticity theory, the model is extended to the three-dimensional stress space. The test results and the others are used to verify the model, and the results show that the proposed model has good accuracy. The proposed model is easy to be numerically implemented. The model has been successfully applied in the elastic-plastic analysis of a cemented “high modulus zone” in a high concrete faced rockfill dam. The influences of the “high modulus zone” on the stress and deformation of the dam and the anti-seepage body are discussed, and the feasibility of using the cemented coarse-grained soils in high rockfill dams is evaluated.