土的应力-应变关系的一种描述模式

通常将由土的剪切试验测得的应力-应变关系曲线(q～ε1曲线)分为应变硬化型和应变软化型,文中提出了一种能同时描述应变硬化型q～ε1曲线和应变软化型q～ε1曲线的新模式,并导出了统一的切线模量表达式,进一步探讨了该应力-应变关系曲线描述模式在拟合应变硬化型曲线时的简化形式,及简化形式中参数取值方法和参数与围压的关系等方面的问题。通过与邓肯-张模型和应变软化模型的对比,结果表明该应力-应变关系曲线描述模式能更好地与试验数据吻合,且用其简化形式拟合应变硬化型曲线时,可以通过调整其中一个参数值来表达出不同的曲线形式,从而体现出土体应力-应变关系的多样性。该应力-应变关系描述模式为发展更一般的非线性弹性模型提供了一定的理论基础。

UNIFORM EXPRESSION OF STRESS STRAIN RELATIONSHIP OF SOILS

In this paper,the stress-strain relationship of soil established from shear tests is distinguished into two kinds-strain hardening type and strain softening type. A new stress-strain model which can not only describes strain hardening stress-strain curve but also strain softening stress-strain curve is presented. The equation of tangent modulus is deduced. The paper presents the simplified form of the expression when it was employed to describe strain hardening stress-strain curve. The method of fixing the parameter and the relationship between the parameters and the confining pressure was studied. Comparing this new model with Duncan-Chang model and the strain softening model, it is found that this new model can better meet test results. The simplified form of new model is more accurately to describe strain hardening stress-strain curve and can describe more kinds of curve comparison with Duncan-Chang mode1. It is able to display variety of the stress-strain curve of soils using a changeable parameter. The unified expression provides a base to develop a general nonlinear mechanics model of soils.