摘要
在Biot固结理论框架下,利用分数阶Kelvin模型描述土骨架流变效应,考虑孔压消散和土骨架流变的耦合作用。通过建立周期性循环荷载的时空域解析函数,在柱坐标系下构建半空间饱和黏土地基的三维轴对称动力固结控制方程。采用Hankel-Laplace联合变换及张量运算推导控制方程在变换域的解析解,然后利用数值反演得出物理场的时空域解。通过算例分析,对循环荷载作用下饱和黏土地基的动力固结特性开展研究。结果表明,饱和黏土在主固结阶段的沉降速率较慢,而次固结阶段的沉降速率加快;循环荷载作用下,土骨架流变性越强,土体的累积沉降发展越快,土体位移波动幅值随黏性阶数的增大而减小,而且黏性阶数越大位移滞后性越明显;土骨架流变性导致孔压响应滞后于有效应力,孔压与有效应力的螺旋曲线发生水平移动;在循环荷载的卸载阶段,正应力随外荷载的减小而减小,但切应力随之增大,土体因发生剪胀现象而产生负孔压。
Under the framework of Biot porous media theory,the fractional order Kelvin model is used to describe the rheological effect of soil skeleton,considering the coupling effect of pore pressure dissipation and skeleton rheology.By establishing a spatiotemporal analytical function for periodic cyclic loads,a three-dimensional axisymmetric dynamic consolidation control equation for a half space saturated clay foundation is constructed in a cylindrical coordinate system.The analytical solution of the control equation in the transformed domain is derived using Hankel-Laplace joint transformation and tensor operations,followed by numerical inversion to acquire the spatiotemporal solution of the physical field.By analyzing numerical examples,the dynamic consolidation characteristics of a saturated clay foundation under cyclic loading are studied.The results indicate that the settlement rate of saturated clay is slower during primary consolidation but faster during secondary consolidation.With cyclic loading,the soil's cumulative settlement development accelerates as the rheological properties of the soil skeleton strengthen.The amplitude of soil displacement fluctuations decreases as the order of viscosity increases,and the more significant the order of viscosity,the more pronounced the displacement hysteresis becomes.The rheological properties of the soil skeleton lead to a lag in pore pressure response compared to effective stress,resulting in horizontal movement of the spiral curve between pore pressure and effective stress under cyclic loading.In the unloading stage of cyclic loads,due to the decrease of normal stress with the decrease of external load,but the increase of shear stress,the soil undergoes shear dilation phenomenon,resulting in negative pore pressure in the soil.
作者
王立安
余云燕
任新
陈辉
WANG Li-an;YU Yun-yan;REN Xin;CHEN Hui(School of Railway Technology,Lanzhou Jiaotong University,Lanzhou,Gansu 730070,China;School of Civil Engineering,Lanzhou Jiaotong University,Lanzhou,Gansu 730070,China)
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2024年第8期2279-2289,共11页
Rock and Soil Mechanics
基金
甘肃省自然科学基金(No.22JR11RA155)
兰州交通大学青年科学基金(No.1200061136)。
