中文摘要：

为了研究温度载荷作用下煤层露头火区上覆岩层受热破坏特性,揭示上覆岩层的强度和变形特征随温度的变化规律。采用MTS8 15.02电液伺服岩石力学试验系统和NM-4A型非金属超声检测分析仪,对岩样进行了25~600℃加温加载试验。试验得出了不同温度条件下岩样受热破坏特征和纵波波速变化规律。结果表明,随温度升高,岩样纵波波速逐渐减小,600℃时砂岩X、Y、Z 3个方向的纵波波速下降了48.54%。高温对岩样的强度有一定的弱化作用,其峰值应力随温度升高而降低,600℃时岩样强度降幅达47.1%。岩样的峰值应变随温度升高而逐渐增大,400℃时峰值应变增大了55.6%,600℃时峰值应变增大了60.9%。随温度升高,砂岩的弹性模量、变形模量均减小,400℃时弹性模量降幅达13.5%,600℃时弹性模量降幅达59.6%。这表明在大面积高温火区的作用下,煤层露头火区上覆岩层产生大量漏风裂隙,热风压增大,致使高温煤体上部空气通过裂隙发生自然对流,从而维持煤体附近一定浓度的氧气。

英文摘要：

This paper is attempting to make an experimental study over the thermo-dynamic destructive features of the overburdened coal seam outcrop fire area by using a nonmetallic ultrasonic testing ana lyzer and a rock mechanics electro-hydraulic system with heat-fracture mechanical properties in a range of temperature from 25 % to 600 ℃ . The experimental heat helps to give out the destructive characteristics of the sample and the rule of the wave velocity changes under different temperatures. The results of the experiment shows that the wave＇ s longitudinal velocity of the rock tends to decrease with the increase of temperature, while the longitudinal wave velocity of the sandstone is spreading in three directions, known as X, Y, Z tends to decrease by 48.54 % at 600 ℃ . The high temperature exerted on the strength of the sample material tends to have a certain weakening effect, with its peak stress tending to decrease with the temperature rise and the strength of the sample dropping by 47.1% at 600 ℃. What is more, the peak strain of the sample is likely to increase with the rise of temperature, with its peak strain increasing by 55.6% at 400 ℃ and increasing by 60.9% at 600 ℃ . Furthermore, the elastic modulus and the deformation modulus of the sandstone may also tend to reduce with the rise of temperature. For example, the elastic modulus may tend to drop by a factor of 13.5% at 400 ℃ and a drop of 59.6% when the elastic modulus is under 600 %. All the above data indicate that under the effects of the large area of high temperature fire area, the overburden of the coal seam outcrop fire area may all produce a large amount of air leakage cracks and increase the hot air pressure, which may in turn result in the natural convection of the coal under the high temperatures through the cracks of coal, thus making it necessary to maintain a certain concentration of oxygen around the coal seam.