Experimental Study On Shear Characteristics Of Filled Joints With Different Morphologies Of Series Sizes

There are major hidden dangers in the safety of weak interlayer in the face of slope engineering,it is of great significance to carry out the study of size effect of Joint with weak interlayer shear strength.Considering that the study of the size effect law of the shear strength of the joint is mainly concentrated on small-size specimens,and the shear test of the size effect of the shear strength of the largesize filled joints indoor has not yet been carried out.Therefore,taking the planar joints,slightly undulating joints and sawtooth rock joints as the research object,the filled group and the non-filled group were compared with the different morphological joints with a series size of 200mm×(100-600)mm,the samples of72 sets were prepared,and the indoor direct shear test study of the size effect of shear strength of the joints with calcite interlayers was carried out.(1)Through repeated experiments,the mixing ratio of rock-like materials was obtained,and a series of size specimen making molds were developed,which can meet the production of samples of different sizes and shapes.Using the 200 k N size effect test system of rock joint,the indoor shear test of the filled joints of a series of sizes was carried out.The results show that:for the non-filled joints,the shear stress-shear displacement relationship curve shows the characteristics of pre-peak hardening and post-peak softening,shear failure is manifested as shear damage and climbing shear failure;for the filled joints,the degree of softening is significantly reduced after the shear stress-shear displacement relationship curve reaches its peak,and the existence of calcite interlayer avoids the direct coupling failure of the upper and lower joints.(2)Using the size effect test system,the effects of different normal stresses and filling degrees on peak shear strength of the joints of the series sizes were carried out.The results show that:for the non-filled joint,with the increase of normal stress,the peak shear strength increases and the degree of shear loss of the joints surface deepens.under the same normal stress condition,the peak shear strength decreases with the increase of filling degree;for filled and non-filled joints,with the increase of size,the peak shear strength fluctuates around a certain value,The law of size effect is not obvious.(3)According to the influence of shear strength of different morphological joints,a series of filled joints indoor shear tests were carried out.The results show that:under the same normal stress condition,for filled and non-filled joints,.Compared with the planar joint without undulation characteristics,the peak shear strength of the slightly undulating joint and the sawtooth rock joint with certain undulation characteristics is greater.which is more favorable for the stability of slope engineering.