冻结风立井白垩系砂岩导热特性的试验研究

为掌握我国西部白垩系富水基岩的热物理特性,采用基于瞬态平面热源技术的Hot-Disk 热常数分析仪对不同温度(-30 ℃、-20 ℃、-10 ℃、-5 ℃、0 ℃、10 ℃、27 ℃)、不同含水(干燥、微量含水、大量含水、饱水)、不同粒径(中粒、粗粒)白垩系砂岩的热导率λ进行了测试。结果表明:饱水砂岩热导率λ随温度降低而先增大后略有减小并趋于稳定,-10 ℃时达峰值3.375 W/m·K;砂岩热导率λ随含水率ω增加呈先增大后减小趋势,λ的范围在0.368-2.242 W/m·K之间,当ω=6.282%-7.539%时热导率λ较大,此时中砂岩最大热导率可达2.242 W/m·K;常温下,相同含水的非饱和白垩系粗砂岩热导率总大于中砂岩0.254~0.284 W/m·K,其中粗、中砂岩平均孔隙度分别为15.169%、21.863%,说明非饱和时砂岩孔隙度越小、颗粒粒径越大则热导率越大。可为西部白垩系地层深厚富水基岩煤矿立井冻结设计提供科学的理论依据。

Experimental Study on Thermal Conductivity Characteristics of Cretaceous Sandstone in Freezing Wind Shaft

To solve the problems of the heat conduction properties of cretaceous strata of western China, a test is carried out on the thermal conductivity of cretaceous sandstone in the shaft at different temperature (-30 ℃,-20 ℃,-10 ℃,-5 ℃, 0 ℃,10 ℃,27 ℃),with different water content(dry, infinitesimal water, plentiful water and saturated),and different grain diameter (medium sandstone, kern stone) by Hot-Disk thermal constant analyzer which was based on Transient Plane Source Method(TPS).The result shows that, with temperature decrease the thermal conductivity of saturated rock first increases then decreases slightly and becomes stabilized, at -10 ℃ it reaches up to the peak of 3.375 W/m·K. The rock thermal conductivity first increases and then decreases with water content increase, λ ranges from 0.368 to 2.242 W/m·K, and λ to be larger when ω=6.282%~7.539%, at this point the max thermal conductivity of sandstone can be up to 2.242 W/m·K. The thermal conductivity of cretaceous kern stone is generally greater than 0.254~0.284 W/m·K of medium sandstone, through test we know that the average porosity of kern stone and medium sandstone are 15.169% and 21.863%,respectively, and which illustrates that in unsaturated case the smaller porosity and larger mineral particle size, the greater thermal conductivity. These results could provide scientific theory basis to the design of western cretaceous deep water-rich bedrock coal mine freezen shaft.