煤层力学性质及可钻性分级试验研究

    Experimental Study on Mechanical Properties and Drillability Classification for the X# Coal Seam

    • 摘要: 利用CMT5305型电子万能试验机测得了某煤层的单轴抗压强度、弹性模量、抗拉强度,并配套圆柱形压头测试了在不同加载位移速率下的静压入硬度值。研究表明:煤岩静压入硬度值不受位移速率影响,但其局部破坏有时间效应,位移速率越大,破坏所需时间越短,且压头压入时煤岩有旋涡式破坏和劈裂式破坏2种;压入硬度法和普氏硬度法对煤层可钻性分级的结果不一致,前者对煤层可钻性分级结果为中软4级,后者对煤层可钻性分级结果为中等坚固~比较软Ⅴa~Ⅵ,分级受室内试验条件影响;压入硬度与抗压强度、弹性模量和抗拉强度的预测模型均可采用对数函数建立,预测模型为准确掌握煤层力学性质提供理论指导。

       

      Abstract: The uniaxial compressive strength, elastic modulus and tensile strength of coal seam were measured by the CMT5305 electronic universal testing machine, the static indentation hardness was also measured by different displacement rate with packaged cylindrical indenter. The results showed that the value of the static indentation hardness of the coal was independent of the displacement rate, but the local broken manners were time-dependent, the greater the displacement rate was, the shorter the broken time was, and there were two destructive modes of vortex and splitting when the coal was pressed by the indenter; the result of the drillability classification of the coal by the indentation hardness method did not agree with that by Polodyakonov hardness method, the former was the forth grade of medium soft and the latter wasⅤa toⅥ grade of medium hard to relatively soft, the classification was also affected by the indoor experimental conditions; the prediction model between the indentation hardness and the compressive strength, elastic modulus and tensile strength can be established by the logarithmic function, and the model can provide theoretical guidance for the accurate understanding of the mechanical properties of coal.

       

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