Using self-researched gas drainage borehole stability dynamic monitoring device, three-dimensional deformation characteristics of borehole under steady vertical load were researched experimentally and systematically. This research indicated that under the action of steady loading, the mechanical deformation path of the simulated gas drainage borehole is gradually complicated, and the decay of the borehole circumferential strain is an important characterization of the prediction and early warning of borehole instability and collapse. The horizontal position of borehole occurs compressive strain, and the vertical of which occurs tensile strain under the action of vertical stress. At the initial stage of loading, the vertical strain is more sensitive than that in the horizontal direction. After a certain period of time, the horizontal strain is gradually higher than the vertical one, and the intersection of the borehole horizontal diameter and the hole wall is the stress concentration point. With the increase of the depth of hole, the strain shows a gradual decay trend as a whole, and the vertical strain decays more observably, but there is no absolute position correlation between the amount of strain decay and the increase in borehole depth, and the area within 1.5 times the orifice size is the borehole stress concentration zone.

利用自主研发的瓦斯抽放钻孔稳定性动态监测装置，对系统在稳态垂直载荷下的三维变形特性进行了实验研究。研究表明，在稳定载荷作用下，模拟瓦斯抽采井眼的力学变形路径逐渐复杂化，井眼周向应变的衰减是预测井眼失稳塌陷和预警的重要特征。井眼的水平位置产生压缩应变，井眼的垂直位置在垂直应力的作用下产生拉伸应变。在加载的初始阶段，垂直应变比水平方向更敏感。一段时间后，水平应变逐渐大于垂直应变，井眼水平直径与孔壁的交点为应力集中点。随着孔深的增加，应变整体上呈现出逐渐衰减的趋势，垂直应变衰减更明显，但应变衰减量与井眼深度增加之间没有绝对的位置相关性，且孔口尺寸的1.5倍以内的区域是井眼应力集中区。