变荷载下变孔压排水边界修正土体一维固结解

One-dimensional consolidation theory with unsteady pore pressure boundary under time-dependent loading

排水边界是影响土体固结快慢的重要因素之一。针对目前透水和不透水这两种理想化的边界条件对实际工程的局限性,提出了严格满足初始条件的变孔压排水边界条件,建立了变孔压排水边界下一维非线性固结理论。采用分离变量法求出该边界条件下的土体超孔隙水压力、土体有效应力,并进一步推导得到按沉降定义的平均固结度U_s和平均孔隙水压力定义的平均固结度U_p以及边界处排水速度v,通过改变边界条件中的参数α,结合具体算例与已有的修正非线性固结理论解的结果进行对比分析。结果表明:提出的变孔压边界条件能更好地反映实际工程工况。

Drainage boundary is one of the important factors that affect the soil consolidation. The current pervious and impervious boundaries have limitations in practical engineering. To deal with this problem,the unsteady pore pressure boundary which strictly meets the initial conditions is proposed. One-dimensional nonlinear consolidation theory with unsteady pore pressure boundary is implemented. The method of variable separation is used to achieve the excess pore pressure and the effective stress of soil. Both the average consolidation degree defined by settlement and excess pore pressure are deduced,as well as drainage velocity at the boundary. Based on a specific example,the results are compared with the existing nonlinear consolidation theory under the same parameters by changing the parameter α in the unsteady pore pressure boundary. The results show that the proposed unsteady pore pressure boundary is more close with the practical engineering conditions.