基于有效固结应力法确定结构性黏性土不排水抗剪强度  

Undrained shear strength determination of structured clays based on effective consolidation stress method

作　　者：曹宇春[1] 杨建辉[1] 

机构地区：[1]浙江科技学院建筑工程学院,杭州310023

出　　处：《岩土力学》2013年第11期3085-3090,共6页Rock and Soil Mechanics

基　　金：国家自然科学基金(No.40406019)

摘　　要：由于结构性的存在使得很多天然黏性土的强度和变形特性不同于重塑土和非结构性土。首先回顾了适用于确定重塑土和非结构性土不排水抗剪强度的有效固结应力法,并推导了相应的方程。在此基础上,对于结构性黏性土,采用两段不同斜率(内摩擦角正切)和截距(黏聚力)的直线模拟其抗剪强度包络线,建立了确定其不排水抗剪强度的有效固结应力法方程;当有效应力小于结构屈服应力时,有效固结应力方程中有效应力部分需乘以0.8的修正系数;只要已知剪切前的有效应力,利用相应的有效固结应力法公式,可确定结构性土体的不排水抗剪强度。利用连云港结构性软黏土的等压固结三轴试验数据,验证了有效固结应力法的适用性。分析表明:对于连云港软黏土的不排水抗剪强度,有效固结应力法的计算结果与试验结果吻合较好;对于结构屈服应力,有效固结应力法的预测结果与试验数据点的拟合结果有一定偏差,但并不明显。The behaviors of strength and deformation of natural soils differ from that of remolded and unstructured soils due to structural property. The effective consolidation stress method for the undrained shear strength evaluation of remolded and unstructured soils is reviewed and the corresponding equations are derived. The equations of the method for the undrained shear strength evaluation of structured clays are hereafter established in terms of the strength envelopes simulated by two segment lines with different slopes （tangents of internal friction angles） and intercepts （cohesions）. The component of effective stress in the equation of effective consolidation stress method should be multiplied by a revised coefficient of 0.8 for the effective stress range less than the yielding stress. The undrained shear strengths of structured soils can be then determined if the consolidation stresses prior to shearing would be known. The applicability of the effective consolidation stress method is validated using the isotropically consolidated triaxial test results of soft structured Lianyungang clay. The undrained shear strengths estimated by the effective consolidation stress method are in good agreement with the laboratory results. Furthermore, the structure-induced yielding stress predicted by the effective consolidation stress method has a certain but negligible deviation from that fitted by the laboratory data.

关 键 词：结构性黏土 不排水抗剪强度 有效固结应力法 内摩擦角 黏聚力 强度包络线 

分 类 号：TU442[建筑科学—岩土工程]