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| Experimental Research on the Microstructure of Thawed Soil after the Sub?way Construction of Freezing Metliod |
| DING Zhi1，ZHANG Meng - ya2，WEI Xin -jiang1，HONG Qi - hao1，ZHENG Yong1 |
| (1. Zhejiang University City College，Hangzliou，Zhejiang 310015，China; 2. Northeast Electric Power Design Institute Co. Ltd，China Power Engineering Consulting Group，Changchun，Jilin 130021，China) |
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Abstract Abstract ： Research purposes ： Freezing method is applied to the construction of cross passage of metro tunnel in coastal soft soil area， which highlights its good sealing performance， high strength and other advantages. However， in the construction of metro tunnel with freezing method，the freeze - thaw circulation will affect tlie engineering properties of soil. The further study on dynamic properties of frozen - thawed soil is necessary. Based on the freezing method construction of the subway connecting passage，this paper scanned the microstructure of artificial frozen - thawed soil through electron microscope，qualitatively described the pore characteristics of the microstructure，particle characteristics and structure mode of connection of tlie saturated frost - thawed soft soil，and analyzed the pore diameter，pore area， and otlier microstructure parameters of artificial frozen - thawed soft soil under microstructure based on Image - Pro Plus analysis software . Research conclusions ：( 1) After the freezing and thawing，the content of micropores decreased，the number of larger pore size increased， surface porosity ratio had developing trend; after freezing and thawing，the pore structure of soft soil became more complex， the performance of the average pore fractal dimension increased. (2) With reduction of the freezing temperature and increase of freezing thawing cycles，the inter - particle pore volume increased, the flocculent structure was more obvious, the role of structural connection had a certain degree of weakening. (3 ) The macroscopic dynamic characteristics can be explained from the microcosmic angle, which can provide the basis for controlling long term settlement after the construction of freezing method.
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Received: 23 May 2016
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2016, Vol. 33 
