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在初始含水率和密度与原位土一致的情况下,通过电阻率试验对上海地铁四号线的粉砂土进行了在30～-30℃条件下的导电特性试验研究。结果表明:未冻水含量较高时,粉砂土的导电性在高电压情况下随着电压的升高而增强;在含水率和密度一定的情况下,粉砂土的导电性与温度密切相关,即电阻率随温度降低而增大,也就是说其导电性随温度的降低而减弱;在温度高于0℃条件下,粉砂土的电阻率随温度变化相对较小;在温度低于0℃条件下,粉砂土的电阻率随温度变化较明显;在30℃≥t≥0℃,0℃>t≥-10℃及-10℃>t≥-30℃三个温度段,分别拟合出温度与电阻率之间相关度较高的回归方程。上述结论可为今后长江三角洲地区类似土层采用电阻率法监测冻结壁的发育状况提供物理基础。
Under the condition that the initial water content and density are consistent with the original soil, the conductivity test of the silt sand in Shanghai Metro Line 4 was carried out at 30 ~ -30 ℃ through the resistivity test. The results show that the conductivity of silt sand increases with the increase of voltage under the condition of high unpressurized water, and the conductivity and temperature of silt sand are close at the same moisture content and density , That is, the resistivity increases with decreasing temperature, that is to say, its conductivity decreases with the decrease of temperature; at temperature higher than 0 ℃, the resistivity of silt soil is relatively small with temperature; at low temperature At 0 ℃, the resistivity of silt sand changed obviously with the temperature. In the temperature range of 30 ℃ ≥t≥0 ℃, 0 ℃> t≥-10 ℃ and -10 ℃> t≥-30 ℃, Regression equations with high correlation between temperature and resistivity were fitted respectively. The above conclusions may provide the physical basis for the similar soil layers in the Yangtze River Delta in the future to monitor the development of the frozen wall by the resistivity method.