不同角度单裂隙对类岩石加卸载强度影响的试验研究

Experimental Study on the Effect of Loading and Unloading Strength for Single Fracture Similar Rock Specimens with Different Angles

天然岩体内部存在大量裂隙,严重削弱了岩体的强度和稳定性,含不同裂隙的岩体在加载和卸载条件下其力学特性有显著区别。为研究含不同角度(裂隙面与水平方向夹角)裂隙的岩体在加卸载时的力学特性,根据相似三定理,制备了含有五组不同角度裂隙(0°、30°、45°、75°、90°)的完整类岩石试件,对每组试件分别进行了单轴和三轴循环加卸载试验,研究裂隙倾角和加卸载对其峰值强度的影响。结果表明:随裂隙角度的增大,单轴峰值强度显著增加,弹性模量增大、而泊松比随角度增加呈现降低趋势;不同倾角的岩石循环加卸载强度随角度增加而增大;三轴峰值强度随裂隙倾角的增加而增大,但围压对裂隙试件强度影响明显,在三轴循环加卸载环境下,强度会随裂隙倾角增加而明显增大。

The stability and deformation characteristics of rock depend mainly on fissures,the mechanical properties of different fractured rock mass under loading and unloading conditions are significantly different.In order to study the mechanical properties of rock mass with different angles during loading and unloading,according to the three similarity theorems,complete specimens with single fracture dip angles of 0°,30°,45°,75°and 90°are prepared,and specimens with different fissure dip angles areloaded in 5 grades according to uniaxial compressive strength,the load of each grade is about 20%of the specimen strength,and the uniaxial and three axle cyclic loading and unloading experiments are carried out to study effect of loading and unloading on its peak strength.The results show that the uniaxial compressive strength increases significantly with the increase of the angle,the elastic modulus increases and Poisson's ratio decreases with the increase of angle,the cyclic loading and unloading strength of rocks with different dip angles increases with the increase of angles,the three axis strength increases with the increase of crack dip angle,the influence of confining pressure on fracture strength is obvious,the three axle cyclic loading and unloading strength increases obviously with the increase of dip angle.