考虑含砂量影响的砂-黏混合土应力-应变关系特性研究

STRESS-STRAIN RELATIONSHIPS OF SAND-CLAY MIXTURES WITH DIFFERENT SAND CONTENTS

将砂与黏土按不同比例干重量均匀混合制成砂-黏混合土,进行不排水三轴剪切试验,研究了含砂量和试验围压对混合土初始切线模量和应力-应变关系的影响,并对其作用机理进行了分析。研究结果表明:含砂量小于50%时,可以认为混合土初始切线模量与含砂量无关。含砂量大于50%小于80%时,初始切线模量随含砂量增加呈线性趋势增长。通过把含砂量参数引入到初始切线模量中对Duncan-Chang模型进行修正,使修正后的模型能够描述含砂量小于80%时混合土的应力-应变关系。当含砂量超过80%,混合土呈应变软化型,随含砂量的增加,初始切线模量逐渐保持稳定,应力-应变曲线峰值应变左移,可应用软化模型对其应力-应变关系进行描述。围压对混合土应力-应变关系有很大影响,在双对数坐标中,随试验围压的增大,初始切线模量呈线性趋势增长。

The sand-clay mixtures are made by mixing sand and marine clay with different dry weight proportions homogeneously.Undrained triaxial tests are conducted to study the effects of sand content variation and confining pressure on the initial shear modulus and stress-strain relationships of the mixtures.Mechanisms are analyzed.Tests results show that there is no obvious relationship between the initial shear modulus and the sand content variation when sand content is less than 50%.For sand-clay mixtures with sand content ranging from 50%to 80%,the initial shear modulus increases linearly with the growing sand content.The sand content parameter should be introduced into the initial shear modulus so that the modified Duncan-Chang model can be used to imitate the stress-strain relationships of the sand-clay mixtures with sand content less than 80%effectively.When the sand percentage is over than 80%,the characteristic of strain softening occurs.The initial shear modulus is kept steady gradually.The peak strain becomes smaller.The softening model is useful to describe the stress-strain relationships of sand-clay mixtures＆nbsp;in this case.The confining pressure has a visible effect on the stress-strain relationship of sand-clay mixtures.As the confining pressure increases, the initial shear modulus shows a linear growing trend in double logarithmic coordinate.