煤炭工程 ›› 2015, Vol. 47 ›› Issue (7): 78-81.doi: 10.11799/ce201507027

• 研究探讨 • 上一篇    下一篇

孔隙水压与轴向荷载作用下试件的破坏特征研究

崔峰,来兴平,曹建涛   

  1. 西安科技大学
  • 收稿日期:2014-10-06 修回日期:2014-12-17 出版日期:2015-07-10 发布日期:2015-07-15
  • 通讯作者: 崔峰 E-mail:cuifeng9418@163.com

Failure behavior of specimen under the action of pore water pressure and load

  • Received:2014-10-06 Revised:2014-12-17 Online:2015-07-10 Published:2015-07-15

摘要: 水压致裂是提高综放工作面顶煤冒放性的有效措施。通过对水压致裂机制的探讨,运用数值模拟的方式完成了不同渗透水压作用下试件强度及加载特性的数值实验,获得了孔隙压力演化规律和致裂特性,提出了评估注水致裂强度劣化的评估指数。结果表明:在孔隙水压作用下试件破坏所需荷载减小;在注水水压小于3MPa时各个试件破裂前,荷载曲线基本呈线性增加的趋势,在达到试件的峰值强度时试件破坏,轴向荷载呈现出迅速跌落的现象。孔隙水压较大时,较早的对试件顶部产生破坏。随着孔隙水压的加大试件的极限荷载及强度逐渐降低,劣化指数Y呈指数型上升趋势,为选择合理的注水压力提供了依据。

关键词: 水压致裂, 致裂机制, 强度劣化, 数值模拟, 顶煤冒放性

Abstract: Hydraulic fracturing is an effective measure to improve the caving effect of top-coal in fully mechanized top coal caving face. Through the discussion of hydraulic fracturing mechanism, the crack tip stress intensity factor expressions and crack initiation pressure and shear failure pressure induced by hydraulic fracturing are deduced. Using numerical simulation method to complete the numerical experiments of specimen strength at different water seepage pressure and loading characteristics, the pore pressure evolution and fracture characteristics are obtained, strength deterioration index is proposed to evaluate the degree of hydraulic fracturing. The results show that: the required load for the specimen damage is reduced under the action of pore water pressure; while injection water pressure is less than 3MPa (before rupture time), the load curve has the linear increasing trend, the specimen is destroyed while reaching the peak intensity of specimen, the axial load shows a rapid drop phenomenon. When the pore pressure increases from 0.5MPa to 2MPa, the load to destroy specimen is decreased gradually, and the stress at monitoring line also has this trend. When Pore water pressure is larger, the top of specimen is damaged earlierly. Strength deterioration evaluation index for assessing hydraulic fracturing shows that, with the increase of pore water pressure, the ultimate load and intensity of specimen are decreased gradually, Y (deterioration index) has the trend of exponential increasing, providing the basis for selecting reasonable water pressure.

Key words: hydraulic fracturing, fracture mechanism, strength deterioration, numerical simulation

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