原状饱和黏土静止土压力系数试验研究  

EXPERIMENTAL STUDIES OF STATIC EARTH PRESSURE COEFFICIENT OF UNDISTURBED SATURATED CLAY

作　　者：黄博[1,2] 胡俊清[1,2] 廖先斌[3] 黄雄[3] 

机构地区：[1]浙江大学岩土工程研究所,浙江杭州310027 [2]浙江大学教育部软弱土与环境土工重点实验室,浙江杭州310027 [3]中交第四航务工程勘察设计院有限公司,广东广州510203

出　　处：《岩石力学与工程学报》2013年第S2期4056-4064,共9页Chinese Journal of Rock Mechanics and Engineering

基　　金：国家自然科学基金资助项目(50708095;51178427)

摘　　要：利用先进三轴仪进行港珠澳大桥岛隧工程原状土K0固结试验,研究不同加、卸载路径下土体静止土压力系数K0变化,分析常用经验公式及规范推荐值所估计静止土压力系数的适用性,并给出基于本次试验结果的预测公式。结果表明:港珠澳沉管隧道底面处的黏土层K0基本为一定值,为0.47;粉质黏土层K0与其先期固结压力成正比,在0.30~0.45范围内,均低于规范和手册对同类土的推荐值;除土性自身的原因外,原状样的胶结作用也会使其K0降低。结构性较强的原状土,在取土后再加载的过程中,K0会先降低至低于其正常固结值,再回升并逐渐稳定。原状黏性土正常固结和超固结时,均可利用前人给出的经验公式对K0进行估计,其中内摩擦角宜为土体正常固结时的有效峰值内摩擦角。A number of K0-consolidation tests are carried out on the undisturbed mud/silt clay and silty clay samples of Hong Kong-Zhuhai-Macao bridge by using advanced triaxial apparatus. The changes of static soil pressure coefficient K0 under different loading and unloading paths are studied;and the applicability of using common formula and recommended value of specifications to estimate the K0 are analyzed,as well as the prediction equation based on test results is given. The results show that:K0 of mud/silt clay at the bottom of the Hong Kong-Zhuhai-Macao bridge immersed tunnel is a basically constant value(0.47). K0 of silty clay is proportional to the preconsolidation pressure and K0 is between 0.30 and 0.45;both of the bounds are lower than the recommended values of specifications and manuals for similar soil. In addition to soil properties,the cementation of the undisturbed samples also could make the K0 reduce. K0 of the strong structural undisturbed soil would decrease to below the values of normally consolidated clay and then rebound and gradually stabilize during loading stages. We can use the empirical formula given by the predecessors to estimate the K0 of normally consolidated and over-consolidated undisturbed clays;and the internal friction angle should be the effective peak internal friction angle of normally consolidated soil.

关 键 词：土力学 静止土压力系数 K0固结 正常固结土 超固结土 

分 类 号：TU431[建筑科学—岩土工程]