基于水热变化的煤矿井筒冻土抗折强度试验

Experiment on flexural strength of frozen soil in coal mine wellbore based on hydrothermal changes

基于水热变化下的人工冻土力学试验是人工冻结法设计过程中进行合理设计和安全施工的前提和必要条件。通过采用设计正交试验及统计拟合方法,针对海测滩煤矿立井井筒处黄土冻土试样进行不同含水率及冻结温度下抗折强度试验,分析了冻土的挠度-抗折强度变化关系及其力学性能,对比了不同含水率及不同冻结温度下冻土抗折强度变化,并对立井井筒黄土基土在冻结过程中的抗折强度建立了基于冻结温度、含水率变化的预测模型。结果表明,立井井筒处冻土的抗折强度随含水率的增大呈先增加后减小变化,在含水率15%~20%时其抗折强度较大;冻结温度与冻土抗折强度呈近线性关系,温度降低,冻土抗折强度增大;采用冻结法施工时冻结参数选择温度-15℃,含水率20%较为合理。

The mechanical test of artificially frozen soil based on hydrothermal changes is a prerequisite and necessary conditions 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 different moisture contents and freezing temperatures were compared.A prediction model based on changes in freezing temperature 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 freezing 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%.