一种横观各向同性强度准则及变换应力空间

ONE KIND OF TRANSVERSE ISOTROPIC STRENGTH CRITERION AND THE TRANSFORMATION STRESS SPACE

考虑岩土介质在自然形成过程中产生的原生各向异性性质,将其简化为一种横观各向同性岩土材料.基于已提出的a强度准则,根据沉积面与有效滑移面在物理空间中位置的相互关系,采用两面的空间夹角作为度量岩土材料原生各向异性在加载条件下发挥强度作用的影响变量.并根据有效滑移面的物理概念,当沉积面与有效滑移面夹角越大,则摩擦特性潜力发挥的越充分,此时对应更高的强度应力比,反之则对应越小的强度应力比.基于上述思想,建立了考虑原生各向异性的强度应力比公式,将其用于修正a准则,进而得到了横观各向同性a准则公式.采用上述横观各向同性a准则公式向各向同性Von-Mises准则公式转换的变换思路,在横观各向同性a准则公式基础上,推导得到了变换应力公式,该公式可由横观各向同性应力空间转变为各向同性应力空间,利用所提出的变换应力方法,可方便的将传统的在偏平面上以Von-Mises准则为基础的二维模型转换为可考虑原生各向异性的三维模型.通过对岩土材料的强度以及真三轴条件下的应力应变关系试验数据预测,验证了所提的横观各向同性a准则及其变换应力公式的有效性及适用性.

Considering the original anisotropic properties of the geomaterials in the process of natural formation,it is simplified as a kind of cross-anisotropy material.Based on a strength criterion,according to the spatial location relationship of depositional plane(DP)and the effective spatial mobilized plane(ESMP)in physical space,the angle of above two planes is regarded as the primary influential factor to measure the strength degree of geomaterial anisotropy.According the concept of ESMP,when the angle between DP and ESMP is larger,the frictional behavior capacity can be fully employed.The stress ratio strength is larger and vice in contrary.Based on the above thought,the stress ratio strength formula for cross-anisotropy material is established.The formula can be employed to revise a strength criterion and a strength criterion considering cross-anisotropy is obtained.The transformation idea of a criterion for transversely isotropic materials formula to isotropic Von-Mises criterion formula is adopted.Based on cross-anisotropy a strength criterion,the transformed stress equation is derived and it can be employed to transform the cross-anisotropy stress space to isotropic stress space.By using the proposed transformed stress(TS)method,it is convenient to convert the traditional two-dimensional constitutive models established on the basis of Von-Mises criterion to the three-dimensional models considering cross-anisotropy.By comparison of the prediction and test results of strength and stress-strain relationship for geomaterials under triaxial loading condition,the validity and applicability of proposed criterion and TS method is demonstrated.