基于能量原理的水-岩耦合下砂岩破坏准则研究

Study on Failure Criterion of Sandstone under Water-rock Coupling Based on Energy Principle

针对深部砂岩水-岩耦合受力情况复杂性问题,采用砂岩流固耦合试验、砂岩破坏准则理论研究与FLAC^(3D)数值模拟验证分析相结合方法,对饱和砂岩在不同围压和孔隙水压作用下的破坏机理与力学特性等进行了深入研究。结果表明:围压对于轴向变形影响要远远小于径向变形,且随着围压增大,岩石延性特征和应变硬化特性越明显,同时孔隙水压越大,岩石破坏强度越低;基于能量原理破坏准则计算的理论值与试验值误差均在5%之内,而其它两个破坏准则远小于试验值,误差值最大分别达到了35.34%和37.11%;FLAC^(3D)数值模拟分析较好地模拟和描述了饱和砂岩三轴压缩破坏过程特征,验证了水-岩耦合作用下基于能量原理的砂岩破坏准则具有正确性和合理性。

In view of the complexity of water-rock coupling force in deep sandstone, sandstone fluid-solid coupling test, theoreti-cal research of sandstone failure criterion and verification analysis by FLAC^3D numerical simulation were combined to study the underlying damage mechanism and mechanical properties of saturated sandstone, under different confining pressures and pore water pressures. The results showed that the influence of confining pressure on axial deformation was much smaller than that on radial deformation. With the increase of confining pressure, the ductility and strain hardening characteristics of rock were more obvious. At the same time, the greater the pore water pressure, the lower the rock failure strength. The error between the theoretical and experimental values calculated by the energy principle failure criterion was within 5 %, while the theoretical values by the other two failure criterias were much smaller than the experimental values, and the error values were up to 35.34% and 37.11% respectively. FLAC^3D numerical simulation analysis well simulated and described the characteristics of tri-axial compression failure process of saturated sandstone, and the sandstone failure criterion based on energy principle under wa-ter-rock coupling was verified to be correct and reasonable.