Experiment on flexural strength of frozen soil in coal mine wellbore based on hydrothermal changes
The mechanical test of artificially frozen soil based on hydrothermal changes is a prerequisite and necessary con-ditions for rational design and safe construction in the design process of artificial freezing method.By designing orthogonal experiments and statistical fitting methods,a flexural strength test was conducted on loess frozen soil samples at the shaft of Haicetan Coal Mine at different moisture contents and freezing temperatures.The relationship between deflection and flexural strength of frozen soil and its mechanical properties were analyzed,and the changes in flexural strength of frozen soil at dif-ferent moisture contents and freezing temperatures were compared.A prediction model based on changes in freezing tempera-ture and moisture content was proposed for the flexural strength of loess foundation soil in the shaft during the freezing process.The results show that the flexural strength of frozen soil at the vertical shaft increases first and then decreases with the increase of water content,and its flexural strength is higher when the water content is between 15％and 20％.The freez-ing temperature has a nearly linear relationship with the flexural strength of frozen soil.As the temperature decreases,the flexural strength of frozen soil increases.When using the freezing method for construction,it is more reasonable to choose a freezing parameter of-15 ℃ and a moisture content of 20％.
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