Experimental study on unconfined compression strength of undisturbed frozen soil around the connection passage
The connection passage of a metro section in a city is constructed by using the freezing method,and the frozen area mainly contains silty clay and fine sand.To ensure the safety of frozen excavation construction process and verify whether the strength of frozen soil wall meets the construction requirements,undisturbed frozen soil samples were taken from the frozen area,and unconfined compression strength tests were conducted on the samples to analyze the strength and failure mode.The results showed that the average compression strength of the frozen soil samples with fine sand was 3.40 MPa on brittle failure.There were two ways to lose its compressive stability,including structural failure and external factors causing melting in the frozen soil,which led to the disintegration of fine sand and the loss its compressive stability;The average compression strength of the silty clay frozen soil sample is 0.67 MPa on plasticity failure,mainly due to the influence of external factors,such as freezing and thawing,which leads to a decrease in the compressive stability of frozen soil.Finally,based on the results and phenomena generated from the experiment,reasonable suggestions for frozen construction are proposed to ensure the safety of the frozen construction process and provide some reference for similar frozen projects.
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