CENTRIFUGAL MODEL TESTS ON HYDRAULIC HEAVE MECHANISM OF EXCAVATION IN COHESIVE SOIL WITH CONFINED WATER
ZHANG Fei1，2，LI Jingpei2，3，YANG Bo2，3，TANG Yao2，3
(1. School of Civil Engineering，Yancheng Institute of Technology，Yancheng，Jiangsu 224051，China；2. Department of Geotechnical Engineering，Tongji University，Shanghai 200092，China；3. Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education，Tongji University，Shanghai 200092，China)
Abstract：Centrifugal model tests were designed to simulate hydraulic heave in low permeable cohesive soil under the action of confined water. The bending moment，horizontal displacement and stability of retaining wall at different excavation depths and confined water levels were analyzed. In addition，the heave deformation and hydraulic failure at excavation bottom were observed. Test results indicate that：excavation bottom uplift and deformation curvature increase with increases of confined water pressure and excavation depth；and cohesive soil progressive fracture appears in the center of foundation pit. At passive side of retaining wall，the resistance of soil gradually decreases；while the bending moment and horizontal displacement of retaining wall become greater. Eventually，vertical crack appears in the soil behind retaining wall；and test foundation pit collapses because of hydraulic heave. When analyzing hydraulic heave stability of foundation pit considering the shear strength of cohesive soil，cohesion c should be multiplied by a reduction factor to take some adverse factors into account，such as interface defect of soil-retaining structure，progressive hydraulic fracture and cohesive soil softening induced by groundwater，etc..
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2013, Vol. 32 
