土石坝沥青混凝土心墙三轴力学特性研究

TRIAXIAL TEST STUDY ON MECHANICAL CHARACTERISTICS OF ASPHALT CONCRETE IN THE CORE WALL OF EARTH-ROCK FILL DAM

在三峡水利枢纽茅坪溪土石坝沥青混凝土心墙材料大量的三轴试验成果的基础上,对沥青混凝土的应力–应变特性关系及其力学特性进行研究。由试验结果可知,沥青混凝土的应力–应变关系曲线是由应变硬化和软化2个阶段组成的,为有驼峰的曲线。在剪切过程中,既有剪缩又有剪胀。另外,沥青混凝土的破坏准则也并非符合莫尔–库仑破坏准则。抗剪强度包络线随着侧压力的增加而呈非线形变化,在高围压作用下,强度包络线向下弯曲。基于以上原因,提出用南水非线性模型来描述沥青混凝土材料的应力–应变特性关系,并将其与邓肯–张模型进行对比。从对比结果可以看出,南水非线性模型能更好地描述沥青混凝土的力学特性。

Based on the triaxial test results in the core wall of Maopingxi earth-rock fill dam which is the part of the Three Gorges Project in China, the stress-strain relationship and mechanical properties of asphalt concrete are studied. From the test results, it is found that the stress-strain curve of asphalt concrete included two phases of strain-harding and strain-softing; and that the triaxial test curve was a hump curve, which consists of shear-dilatancy and shear-compression during the shear test. The failure criterion of asphalt concrete was not in good agree with the Mohr-Coulomb criterion. The envelope line of shear strength was nonlinearly changing and downward bending with the increasing of confining pressure. The Nanshui nonlinear model was adopted to describe the characteristics of the stress-strain relationship of the asphalt concrete and compared with the Duncan-Chang nonlinear model. The comparative results indicated that the Nanshui nonlinear model seemed better to describe the mechanical properties of the asphalt concrete.