天然结构性黏土的各向异性边界面模型

提出了一个可同时描述结构性和各向异性特征的适用于天然黏土的边界面本构模型。该模型具有如下特点:①采用了一个同时含有各向异性张量和结构性参数的边界面;②通过初始固结应力状态来确定各向异性张量的初始值以反映初始各向异性,通过各向异性张量随塑性应变的演化规律来描述荷载作用下的诱发各向异性;③通过结构性参数取一个较大的初始值得到一个扩张的边界面,从而反映结构性土的初始高刚度和强度峰值;④通过引入结构性参数随塑性应变的累积逐渐减小的演化规律来模拟土的结构的损伤以及应力应变曲线的软化过程。通过对几组典型的结构性黏土的试验进行模拟初步验证了模型的合理性和有效性。

Anisotropic bounding surface model for natural structured clays

Natural clays are usually structured clays due to their grain cementation during the long deposition process,and exhibited anisotropic deformation behavior originating from the anisotropic arrangement of grains.A pragmatic bounding surface model was proposed for natural structured clays with emphasis both on structure and anisotropy.An anisotropic tensor and a structural parameter were involved in the formulation of the bounding surface,which served as a reference surface for defining plastic yielding and modulus.The initial anisotropy of natural clays was described by properly assigning the initial value of the anisotropy tensor,which depended mainly on the initial stress state.The anisotropy induced by the following loading process was described by an evolution law of the anisotropic tensor.Through assigning an initial value to enlarge the bounding surface the high intact stiffness and peak strength behavior of structured clays were described,and appreciable reduction of stiffness and strength due to destructuration were considered by assigning the structural parameter a descending function with the accumulation of plastic strain.Validity of the model was verified by the test data of several structured clays.