微波加载路径对煤体致裂效果影响试验研究

Experimental study on the effect of microwave loading path on coal cracking

为了探索微波的加载路径对微波致裂煤体效果的影响,利用自主研制的微波辐射试验装置开展了不同微波加载路径下的煤体致裂试验,研究了微波辐射前后煤样的P波波速、抗压强度、弹性模量、煤样表面裂隙演化及煤体微结构损伤因子的变化特征,揭示了不同微波加载路径对煤体致裂效果的影响规律。结果表明:微波辐射后煤样P波波速平均降幅为40.13%,其中微波连续加载条件下降幅高达56.47%;煤体抗压强度、弹性模量受微波辐射影响较明显,平均抗压强度降幅高达74.91%,弹性模量降幅均超过65.01%,其中连续加载下高达80.11%;煤体累积损伤因子与加载路径有关,不同微波加载路径对煤体内部微结构造成不同程度的损伤;微波连续加载与间歇加载均促进煤体表面裂隙的发育,在连续加载下,煤样表面裂隙更发育,破坏更显著。因此,煤体微波加载路径的改变能有效致裂煤体,在微波能量为216 kJ的试验条件下,通过微波连续辐射煤样,可最大程度对煤体进行致裂,煤体的致裂效果达到最优。

In order to explore the influence of microwave loading path on the effect of microwave cracking coal,in this paper,a self-developed microwave radiation experiment device was used to carry out coal cracking experiments under different microwave loading paths,and the P wave velocity,elastic modulus,coal surface crack evolution and coal microstructure damage of coal samples before and after microwave radiation were studied.The change characteristics of the factors reveal the influence of different microwave loading paths on the cracking effect of coal.The results showed that the average P-wave velocity of coal samples decreased by 40.13%after microwave radiation,and the decrease amplitude of microwave continuous loading was 56.47%;the elastic modulus of coal was significantly affected by microwave radiation,the average compressive strength has dropped as much as 74.91%,and the average elastic modulus decreased evenly under different paths,the elastic modulus decreases by more than 65.01%,and up to 80.11%under continuous loading;the cumulative damage factor of the coal body is related to the loading path,and different microwave loading paths cause different degrees of damage to the internal microstructure of the coal body;both continuous microwave loading and intermittent loading promote coal.The development of cracks on the surface of the coal under continuous loading,the development of cracks on the surface of the coal sample is more complex and the damage is more significant.Therefore,the change of the microwave loading path of the coal can effectively crack the coal.Under the experimental conditions of microwave energy of 216 kJ,the continuous microwave radiation of the coal sample can crack the coal to the greatest extent,and the coal has the best cracking effect.