成都黏土强度特性的试验研究及其基坑土压力的计算方法  

Experimental study on the shear strength of Chengdu clay and the method to compute the excavation earth pressure

作　　者：Camila Mendoza 毛坚强[1] 夏自赛 赵卫星 邱童春 王伟浩 Camila Mendoza;MAO Jianqiang;XIA Zisai;ZHAO Weixing;QIU Tongchun;WANG Weihao(School of Civil Engineering,Southwest Jiaotong University,Chengdu 610031,China;CRCC Kunlun Metro Investment&Construction Management Co.Ltd.,Chengdu 610081,China)

机构地区：[1]西南交通大学土木工程学院,四川成都610031 [2]中铁建昆仑地铁投资建设管理有限公司,四川成都610081

出　　处：《四川建筑科学研究》2023年第4期50-57,78,共9页Sichuan Building Science

摘　　要：以褐黄色、砖红色、灰白色等3种典型的成都黏土为对象,通过三轴压缩试验研究了其母体土在天然含水量、饱和状态时的抗剪强度特性;通过直剪试验研究了其中的裂隙在无水、有水时的抗剪强度特性;建立了考虑裂隙时的土压力计算公式,可供设计使用。此外,通过膨胀力试验确定了这3种土的膨胀力。研究结果表明,饱和状态时母体土的黏聚力可降至天然含水量时的18%~46%,并会对基坑的土压力及稳定性产生显著影响。裂隙面对土压力的影响程度与其方向密切相关。在不利的情况下,裂隙面会导致主动土压力显著增大、被动土压力显著减小,成为影响基坑土压力及稳定性的决定因素。总体上看,对成都黏土基坑土压力及稳定性产生不良影响的主要因素是水及土中的裂隙,而膨胀性的影响相对较小。Taking three typical Chengdu clay with brown yellow,brick-red and off-white colors as the object,the shear strength of the soil in natural water content and saturation content was studied by triaxial compression test.The shear strength of the soil under the condition of fissure with/without water was studied by direct shear test.The formulae to compute the earth pressure of fissured clay were established,which were applicable to the design.Moreover,the swelling forces of the three kinds of clays were determined by swelling force test.It is found that the cohesion of saturated clays will decrease to 18%-46%of the cohesion of the clays in natural water content,which affects the earth pressure and the stability of excavation.The influence of fissure in clay to the earth pressure depends on the dip of fissure.When the dip of fissure is adverse,the active/passive earth pressure will increase/decrease appreciably,then the fissure becomes the key factor to affect the earth pressure and the stability of excavation.In summary,water and fissure are the main influence factors to the earth pressure and stability of excavation in Chengdu clay,while the influence of dilatability of clay is smaller.

关 键 词：成都黏土 裂隙面 抗剪强度 基坑 土压力 

分 类 号：TU432[建筑科学—岩土工程]