二元介质模型对重塑黄土的适用性探讨

DISCUSSION ON APPLICABILITY OF BINARY-MEDIA MODEL TO REMOLDED LOESS

为了论述二元介质模型对于重塑黄土的适用性,针对重塑黄土开展了三轴压缩试验,结合轴向应力-应变曲线及试样的破坏形态分析了围压对其受力变形的影响规律,将其受力及破坏的特点与二元介质模型的基本假设进行了对比,指出二元介质模型可以模拟重塑黄土的受力变形规律。在此基础上,根据模型各参数特点建议了参数厘定的基本思路,并通过与试验数据对比验证了厘定思路的有效性。本文建议的参数确定顺序为“胶结元弹性模量→破损率分布→摩擦元参数→局部应变系数”。结果表明,重塑黄土在三轴压缩情况下呈现二元受力状态,二元介质模型可以很好地描述重塑土的应力-应变关系。围压越大,结构破损越快。对于软化型曲线,加载后期摩擦元分担了绝大部分轴向荷载。随着曲线向硬化型过渡,加载后期摩擦元分担的荷载逐渐减小。

The main objective of the present study is to verify the applicability of binary-media model to remolded loess.To this end,triaxial compression tests are carried out.The stress-strain relationships and failure modes of specimen are obtained.The effects of confining pressure on the deformation behavior of specimen are analyzed.Moreover,we compare the characteristics of deformation behavior of remolded loess and the basic assumptions of binary-media model.The binary-media model is supposed to be a suitable approach to describe the mechanic behavior of remolded loess.Therefore,we proposed a parameter determination rule based on the characteristics of each parameter.The validity is further verified through the comparison between the fitting curves and the testing data.The suggest order of parameter determination is'the elastic modulus of the bonded element→the breakage ratio→the parameters of frictional element→local strain coefficient'.The results indicate that double bear state is found in remolded loess sample and the stress-strain relationships of sample can be precisely described by the binary-media model.The higher the confining pressure,the faster the structural damage.Moreover,the frictional element shares most of the axial load in the late period of loading regarding the softening curve.With the transition of the stress-strain curve to the hardening type,load shared by the friction element decreases gradually at the late period of loading.