考虑应力路径与累积变形影响吹填土力学特性

Mechanics Characteristics of Soft Dredger Fill Considering Stress Paths and Cumulative Deformation

应力路径与累积变形量影响土体的力学特性。本文以天津滨海新区有一定结构强度的吹填土为研究对象,采用WF应力路径试验仪对土体施加不同的应力路径,再控制土体的不同的累积变形量,在此基础上,进行三轴不固结不排水试验,探讨不同应力路径及初始累积变形对吹填土变形特性、强度特性以及孔隙水压力变化规律。试验结果表明,土体三轴剪切应力-应变关系曲线形状与应力路径阶段累积变形量密切相关,应力路径对土体抗剪强度大小以及抗剪强度包线形状有明显影响,抗剪强度指标粘聚力受应力路径的影响比内摩擦角大。土体孔压变化不仅与应力路径有关,还与土体结构屈服有关。3种不同应力路径下,有效应力路径在土体结构屈服前后都出现明显的偏转,呈现为"S"型。土体的结构屈服应力并不是一个定值,随着应力状态的变化而变化。

The mechanical properties of soil was affected by the stress path and the cumulative deformation. The soft dredger fill possessing a certain structural strength in Tianjin Binhai New Area was investigated. Through the triaxial unconsolidation undrained test using the WF stress path apparatus,different stress path was imposed on the soil samples and the different cumulative deformation of soil mass was controlled,the effect of the different stress path and initial cumulative deformation on the soil deformation characteristic,strength characteristic and pore water pressure were obtained. The results showed that the stress-strain relationship curve shape of the soil triaxial shear was closely related to cumulative deformation in the different stress path of loading,the stress path has obvious influence on the shear strength and envelope curve of soil. The cohesion as one of the shear strength index affected by stress path was greater than angle of internal friction affected,The pore pressure of soil was related to not only the stress path but also the soil structure yield stress. Before or after the soil structure yield,the three different effective stress paths have changed obviously and appeared as an inflection of＂S＂sharp. The structure yield stress of soil was not a constant and changed with stress state.