节理倾角对砂岩强度及物理特征的影响

节理岩体广泛存在于实际工程中,深入研究节理倾角对岩体强度和物理特征的影响,对节理岩体工程稳定性研究具有重要的意义。通过完整及含不同节理倾角岩样在不同围压下的三轴加载破坏试验及声波测试试验,探讨了节理倾角对砂岩强度及物理特性的影响规律。试验结果表明①随着节理倾角的变化,岩样纵波波速衰减率有所不同,节理倾角为60°时岩样波速衰减率最大。②节理岩样的弹性模量随倾角大小的变化规律是E_完整>E _90°>E _30°> E _60°。③在同一节理倾角下,岩样峰值强度随着围压的增加而增大;在同一围压下,岩样峰值强度随着节理倾角的变化表现出明显的各向异性。④节理岩样的黏聚力随着节理倾角的变化呈现出U型的变化趋势,且在节理倾角为60°时黏聚力最小;同时内摩擦角随着节理倾角的增大而逐渐增大。由上述成果可知,节理倾角对砂岩强度和物理特性影响较大,节理倾角为60°时,影响程度最大。

Influence of Dip Angle of Joints on the Strength and Physical Properties of Sandstone

Since jointed rock mass exists extensively in practical engineering,in-depth research on the effect of joint's dip angle on rock strength and physical characteristics is of great significance to the stability of jointed rock mass projects.The influence of joints on sandstone's strength and physical properties is investigated through triaxial loading test and acoustic test on intact rock specimen and jointed rock specimens with different joint angles under varying confining pressure.Results are concluded as follows:(1 )With the change of dip angle,the decay rate of longitudinal wave velocity of rock varies,reaching the maximum when dip angle is 60°.(2)The elastic modulus of intact rock is the largest,followed by those of jointed rock specimens with 90°dip angle,30°dip angle,and 60° dip angle.(3)Given the same dip angle,the peak strength of rock increases with the increase of confining pres-sure;while under the same confining pressure,the peak strength of rock specimens displays obvious anisotropy withthe change of dip angle.(4)The cohesion of jointed rock specimens changes in a U-shape curve with varying dip angle,and reaches the minimum when dip angle is 60°;the internal friction angle increases with the increase of dip angle.In conclusion,joints have remarkable influence on the strength,deformation,and physical properties of sandstone.In particular,the influence reaches the maximum when joint's dip angle is 60°.