考虑损伤特征的冻风积土加载模型与试验研究

Study of Frozen Eolian Soil Loading Model and Experiment Considering Damage Characteristic

摘要:

为了研究冻风积土在不同温度、各级围压条件下的应力—应变关系与加载损伤特佂,通过对不同负温不同围压条件下的冻风积土试样进行三轴剪切试验,获得其应力—应变关系曲线。按照用切线模量定义损伤变量方法对Duncan-Chang非线性模型变换得到了损伤变量随偏应力的演化规律表达式,引入具有衰减特性的负指数控制方程用以描述切线模量随偏应力增加而衰减特征。将损伤变量和切线模量的控制方程导入损伤本构关系中推导出了冻风积土加载损伤模型。研究发现:①损伤变量是一个依赖于围压及抗剪强度指标c、φ值并随偏应力不断演化的变量;②加载损伤模型在偏应力较小时描述冻风积土在三轴剪切过程中的应力—应变发展关系较为理想。

Abstract:

In order to study the stress-strain relation and loading damage characteristics of frozen eolian soil under different temperatures and various levels of confining pressures, this paper obtained the stress-strain curves of frozen eolian soil specimens from triaxial shear tests under the condition of different negative temperatures and confining pressures. The expression of damage variable as a function of deviatoric stress was acquired by transforming Duncan-Chang nonlinear model according to the damage variables tangent modulus definition method, and a negative exponential governing equation with attenuation characteristics was introduced to describe the attenuation characteristics of tangent modulus with increasing deviatoric stresses. By substituting thegoverning equation of damage variable and tangent modulus into the damage constitutive relation, the load damage model of frozen eolian soil was deduced. The study found that: (1) the damage variable is dependent on the confining pressure and shear strength parameters (c、φ) and is a constantly evolved variable in response to the deviatoric stress; (2) the loading damage model can describe the stress-strain relationship of frozen eolian soil under triaxial shearing conditions when the deviatoric stress is small.