接触面模型对面板与垫层间接触变形及面板应力的影响

对某在建面板堆石坝进行了三维有限元静、动弹塑性计算,分析了接触面模型对面板与垫层间接触面变形及面板应力的影响。面板与垫层接触面分别采用:双曲线(仅静力计算)、理想弹塑性及广义塑性接触面模型。结果表明:竣工期,3种模型计算的面板应力是基本一致的。满蓄期,3种模型计算的面板顺坡向应力分布规律基本一致,但面板坝轴向应力的分布规律和量值有较明显的差别。蓄水时广义塑性接触面模型计算的接触面的应力路径和剪切位移与双曲线和理想弹塑性存在较大的差异。在地震荷载下,理想弹塑性和广义塑性接触面模型计算的地震后坝体残余变形引起的面板顺坡应力基本一致,但面板坝轴向应力差别较大。理想弹塑性模型只有当应力达到峰值时才产生塑性变形,这样会低估接触面的残余变形,不能与坝体残余变形相协调,高估了坝体残余变形对面板应力的影响。广义塑性接触面模型能更好的反映三维条件下接触面的剪胀、剪缩、硬化、软化、循环残余变形及颗粒破碎特性,更符合实际情况。

Effects of interface models on deformation of interface between slab and cushion layer and slab stress of concrete faced rock fill dam

Three-dimensional static and dynamic elasto-plastic finite element analyses are conducted on a concrete faced rock fill dam. Three different soil-structure interface models are used to simulate the interface between slab and cushion layer, including hyperbolic model (only for static analysis), ideal elasto-plastic model and ageneralized plastic model. The slab stresses are nearly the same among three interface models after construction. The slope-direction slab stresses are also slightly different among three interface models during impoundment, while the axial-direction slab stresses have clear differences. The stress path and shear deformation between slab and cushion layer calculated by the generalized plastic model are different from those by the hyperbolic and ideal elasto-plastic models during impoundment. The slope-direction stress induced by the residual deformation is slightly different between the generalized plastic and ideal elasto-plastic interface models, but the axial-direction stress is much larger for the ideal elasto-plastic model. The ideal elasto-plastic model can only produce plastic deformation when the stress reaches the peak strength, and the shear deformation of interface during earthquakes will be underestimated. The generalized plastic interface model can reflect the dilative and contractive responses, strain hardening, softening, particle breakage and cyclic residual deformation, which is more close to reality.