测定不同抽放程度的煤体硬度变化,是探索预抽瓦斯防止煤与瓦斯突出机理必不可少的一项参数。一般测定煤层硬度的方法是在井下煤壁或采出煤样进行测定,由于煤样中瓦斯已大量释放,因此不能从测定结果获得煤的硬度与不同抽放程度的关系指标。由中国矿院采矿系于1980年研制成功的油压针刺硬度测定器,则可在不同深度钻孔内测定煤层原生状态与不同抽放程度煤体的相对硬度值。测定时向煤层打φ75毫米钻孔至煤层某小分层层位,然后将测定器送入孔底后由油泵推动活塞使胶球径向膨胀,将测定器固定在孔内。再由油泵推动另一活塞将顶针刺入煤体。在不同抽放程度的钻孔中, Determining the change of hardness of coal body with different pumping degree is an indispensable parameter to explore pre-pumping gas to prevent coal and gas outburst mechanism. Generally, the method of determining the hardness of coal seam is to measure the coal wall in coal mine or to extract the coal sample. Since the gas in the coal sample has been released in a large amount, the relationship between the hardness of coal and different drainage degree can not be obtained from the measurement results. The hydraulic acupuncture hardness tester developed successfully by the mining department of the Chinese Academy of Mining in 1980 can measure the relative hardness of the coal body in different depths and the different degree of pumping. Measure to the coal seam when drilling φ75 mm to a small layer of coal seam layer, and then the measuring device into the bottom of the hole by the oil pump to promote the piston radial expansion ball, the detector fixed in the hole. Another plunger driven by the pump to push the thimble into the coal. In the drilling of different drainage levels,