STUDY ON THE INFLUENCE OF FILLING ON MECHANICAL PROPERTIES OF STRUCTURAL SURFACE UNDER REPEATED SHEAR CONDITION

Structural plane plays an important role in stability of rock mass. Many engineering accidents are caused by structural planes. This phenomenon has attracted enough attention. Up to now, the related researches on structural plane mainly include shearing curve description, impact of roughness, combination, filling and other factors on shear strength. In general, these researches are based on that the structural plane bears static load. In fact, it is very common for structural planes to bear cyclic shear load under conditions of dynamic load of earthquake, water level rise and fall, explosion and so on. However, there is less study on mechanical property of structural plane when it is under cyclic shear load. The paper is based on direct shear test. Influence of filled state on deformation and strength of structural plane is studied. Structural planes of four aspertity inclination angles are made using steel mould and concrete. Then several times direct shear tests are conducted under same normal stresses and two filled states. At the same time, shear stress and normal displacement are recorded. The analysis on shear stress-shear displacement and normal displacement-shear displacement curve shows that the asperity inclination angle become larger firstly and structural plane is easier to be cut. For the same shear failure style, if the normal stress increases, the structural plane will be worn or cut more serious, and the maximum normal displacement is lower. If the asperity inclination angle increases, the zig-zag pattern will be worn or cut more. From the second shear time, the structural plane is worn every time and not be affected by asperity inclination angle. After the filling, the structural plane is damaged like before. However, this factor makes the structural plane climbing further, weakens the cutting or wearing degree, and adds the normal displacement meanwhile.