PPGF-灰岩胶结面剪切力学特性试验研究

Experimental Study on Shear Mechanical Properties of PPGF-Limestone Bonding Surface

为探究浆液—裂隙胶结面的剪切开裂破坏规律与力学响应机制,以新型石墨烯基注浆材料PPGF为研究对象,开展了不同石墨烯掺量、不同裂隙粗糙度以及不同法向载荷条件下的PPGF-灰岩胶结体直剪试验,得到了石墨烯、裂隙粗糙度与法向载荷对胶结面开裂、剪切应力与法向位移的影响规律。结果表明:随石墨烯掺量的增加,最大剪切应力呈先增大再减小的变化规律,并且掺量为0.036%时增幅最大。当胶结面的剪切破坏以爬坡滑移为主导时,石墨烯与法向载荷对剪胀位移的影响较小,当剪切破坏以剪断滑动为主导时,石墨烯和法向载荷对剪胀位移影响较大。石墨烯可以增加PPGF的黏结强度,延缓胶结面开裂。开裂剪切位移随粗糙度的增大而增大,随法向载荷的增加而减小。

In order to explore the shear cracking failure law and mechanical response mechanism of the slurry crack bonding surface,a new graphene based grouting material PPGF was taken as the research object.Direct shear tests of PPGFlimestone bonding body were carried out under different graphene content,crack roughness,and normal load conditions.The influence of graphene,crack roughness,and normal load on the cracking,shear stress,and normal displacement of the bonding surface were obtained.The results show that with the increase of graphene content,the maximum shear stress shows a pattern of first increasing and then decreasing,and the increase is maximum when the content is 0.036%.When the shear failure of the bonding surface is dominated by climbing slip,the influence of graphene and normal load on the shear expansion displacement is relatively small.When the shear failure is dominated by shear slip,the influence of graphene and normal load on the shear expansion displacement is relatively large.Graphene can increase the bonding strength of PPGF and delay the cracking of the bonding surface.The cracking shear displacement increases with the increase of roughness and decreases with the increase of normal load.