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| Experimental study on pore features and dynamic behaviors of soft clay under different confine pressures during freezing |
| KONG Bowen1，2，DING Zhi3，HE Shaoheng1，2，ZHUANG Jiahuang4 |
| (1. Research Center of Coastal and Urban Geotechnical Engineering，Zhejiang University，Hangzhou，Zhejiang 310058，China；2. Engineering Research Center of Urban Underground Development of Zhejiang Province，Hangzhou，Zhejiang 310058，China；3. Department of Civil Engineering，Zhejiang University City College，Hangzhou，Zhejiang 310015，China；4. Guangzhou Metro Design and Research Institute Co.，Ltd.，Guangzhou，Guangdong 510030，China) |
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Abstract The construction of subway connection channels in Hangzhou is mostly carried out by freezing method，which leads to uneven settlement during operation. In the whole range of frozen soil，the freezing conditions change with the relative relationship between the soil and the freezing pipe. Soil samples frozen under different freezing conditions were obtained using sample making instrument invented by the authors. Nuclear magnetic resonance(NMR) tests were performed to study the variation of pore size distribution curve of freezing-thawing soil under different freezing conditions, and the pore pressure，strain and stiffness of the samples were deeply explored combined with dynamic triaxial test. A concise pore pressure prediction model of soft clay under artificial freezing with clear physical parameters was established. The results show that, with decreasing the freezing temperature，frost-heaving brings about worse destruction of the soil structure. During freezing-thawing period，the confining pressure can effectively compact the framework structure of the soil and reduce the deformation under cyclic loads. The limit value of the pore pressure is linearly correlated with the area of medium pores of pore size distribution curve.
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2020, Vol. 39 
