单级等速加载下高压缩性软土非线性大应变固结解析解  

Analytical solutions for one-dimensional nonlinear large-strain consolidation of high compressible soil under a ramp loading

作　　者：仇超 李传勋[1] 李红军 QIU Chao;LI Chuan-xun;LI Hong-jun(Faculty of Civil Engineering and Mechanics,Jiangsu University,Zhenjiang,Jiangsu 212013,China;Zhejiang Real Estate Division,Greenland Holding Group,Hangzhou,Zhejiang 310015,China)

机构地区：[1]江苏大学土木工程与力学学院,江苏镇江212013 [2]绿地浙江事业部,浙江杭州310015

出　　处：《岩土力学》2021年第8期2195-2206,共12页Rock and Soil Mechanics

基　　金：国家自然科学基金(No.51878320)。

摘　　要：饱和软土大应变固结理论涉及复杂的材料非线性和几何非线性问题,致使其解析解很难获得,但非线性大应变固结模型解析解的工程意义却不言而喻。目前土体非线性压缩和渗透特性通常采用e-1gσ’和e-1gkv(e为孔隙比,σ’为有效应力,kv为渗透系数)非线性关系描述。但大量室内固结渗透试验的结果表明,高压缩性软土发生较大应变时该非线性关系不再适用,而1g(1+e)-1gσ’和1g(1+e)-1gkv非线性关系却能有效描述高压缩性软土的有效应力、渗透系数与孔隙比间的非线性变化规律。基于此,建立了变荷载下高压缩性软土一维非线性大应变固结模型,并给出特定参数下该固结模型的精确解析解和普适条件下固结模型的近似解析解。将应用固结模型计算的沉降曲线与室内等速加载下的试验沉降曲线对比,验证了该解析理论的可靠性。在此基础上,通过大量的计算研究参数Ic和α、外荷载和加荷速率对固结性状的影响。结果表明:压缩指数Ic一定时,α越小,土层的固结速率越快,底部超静孔压消散越快;α一定时,Ic越小,土层的固结速率越快,底部超静孔压消散越快。按沉降定义的平均固结度Ust一般大于按孔压定义的平均固结度Upt,即沉降的发展速率要快于孔压消散速率。Ic(α-2)>1时,土层的沉降速率随外荷载的增加而减慢;Ic(α-2)<1时,土层的沉降速率随外荷载的增加而加快;Ic(α-2)=1时,土层的沉降速率与外荷载的大小无关。外荷载一定时,土层的平均固结速率随加荷速率增大而加快,同一深度处的超静孔压随加载速率增大而减小。The analytical solution for the nonlinear large strain consolidation model is significant for the actual engineering.However,since the large-strain consolidation theory of saturated soft soil involves complex material nonlinearity and geometrical nonlinearity problems,it is usually challenging to obtain an analytical solution for the large strain consolidation models.At present,the nonlinear compression and permeability characteristics of soils are usually described by e-1 gσ’and e-1 g kv(e is the void ratio,σ’is the effective stress,and kv is the permeability coefficient).However,large numbers of laboratory consolidation tests show that those nonlinear relationships are no longer suitable for the high compressibility soft soil with large strain.In contrast,the nonlinear relationships between the void ratio and effective stress as well as the void ratio and permeability coefficient of soft soil with high compressibility can be described by 1 g(1+e)-1 gσ’and 1 g(1+e)-1 gkv more effectively.Therefore,in this study the one-dimensional nonlinear large strain consolidation model of the high compressible soft soil under a ramp loading is developed,and the exact analytical solution with the specific parameters and the approximate solutions under the general conditions are developed.The reliability of the proposed analytical solutions is validated by comparing the calculated settlement curve with the experimental settlement curve under a ramp loading in the laboratory.On this basis,the influences of parameters(Ic andα),external load,and loading rate on the consolidation behavior are investigated by numerous calculations.The results show that at a certain compression index Ic,the smaller theα,the faster the consolidation rate of the soil layer,and the faster the dissipation of the excess pore-water pressure at the bottom of the clay layer.Conversely,asαis constant,the smaller the Ic,the faster the consolidation rate of the soil layer,and the faster the dissipation of the excess pore-water pressure at the botto

关 键 词：高压缩性软土 非线性 大应变 变荷载 解析解 

分 类 号：TU411.3[建筑科学—岩土工程]