非饱和土土压力在盂县基坑工程中的应用  

Earth Pressures for Unsaturated Retaining Structures and Application in Supported Excavation in Yu County

作　　者：杨建民[1,2] 张正 窦国松 朱志根 刘阳 Yang Jianmin;Zhang Zheng;Dou Guosong;Zhu Zhigen;Liu Yang(School of Civil Engineering,Tianjin University,Tianjin 300350,P.R.China;Key Laboratory of Coast Civil Structure Safety,Ministry of Education,Tianjin University,Tianjin 300350,P.R.China;China Railway No.3 Engineering Group Co.,Ltd,the Third Engineering Co.,Ltd.,Taiyuan 030001,P.R.China)

机构地区：[1]天津大学建筑工程学院,天津300350 [2]天津大学滨海土木工程结构与安全教育部重点实验室,天津300350 [3]中铁三局集团第三工程有限公司,太原030001

出　　处：《地下空间与工程学报》2021年第2期541-555,共15页Chinese Journal of Underground Space and Engineering

基　　金：天津大学北洋学者-青年骨干教师计划。

摘　　要：按照经典土压力理论进行基坑支护设计,非饱和土地区基坑支护结构实测位移通常远小于设计值,其中一个重要原因是未按非饱和土特性计算土压力。针对山西盂县某基坑工程实例,根据勘察报告与Van Genuchten模型确定非饱和黄土土水特征关系曲线。严格证明了总黏聚力法和卢宁吸应力法两种方法在计算非饱和土土压力时完全等效。应用非饱和土理论,考虑基质吸力的影响,计算支护结构土压力,按照规范方法计算支护结构变形。选取坑边超载较小的两工段,按照非饱和土土压力理论设计并施工灌注桩和SMW工法桩进行试验,结果表明,采用非饱和土理论设计所得支护结构主动土压力有所减小而被动土压力有所增大,支护结构内力与变形远小于规范方法计算值,且更接近于实测值。本工程非饱和土饱和度变化范围内,按非饱和土理论计算所得支护结构受力和变形都在规范方法计算值80%以内。The measured displacement of the supporting structure in the deep excavation is usually much smaller than those calculated by classic earth pressure theories. One of the important reasons is that the matrix suction of unsaturated soil is not taken into account,which reduces the shear force index. In this paper,a project was made in Yu County,Shanxi Province,and the presumed loess soil-water characteristic curve was get based on the geotechnical investigation report and Van Genuchten model. This paper strictly proved that the total cohesion method and Ning Lu suction stress method were equivalent in calculating unsaturated soil pressure. Unsaturated soil theory was applied and the matric suction effect on earth pressures for unsaturated retaining structures was considered. The deformation of supporting structure was calculated according to the standard method. Two sections were selected to carry out the test of the bored piles and the Soil Mixing Wall( SMW) piles,respectively. It is found that the active earth pressure decrease while passive earth pressure increases,and the force and deformation of the retaining structure obtained by the earth pressures of unsaturated soil is much smaller than that of the design by the standard method,which is closer to the measured value. Within the variation range of unsaturated soil saturation,the stress and deformation of the supporting structure calculated according to the unsaturated soil theory are within 80% of the value calculated by the standard method.

关 键 词：非饱和土 基质吸力 土压力 基坑支护 

分 类 号：TU43[建筑科学—岩土工程]