If the true dip line of one or two joint planes plot within a sliding zone of double-faced slope, a double-faced sliding failure can be possible.
如果有一两个节理面真倾向线落在滑动区内，滑动破坏才可能发生。
2
When the dip of bedding is less than the friction Angle of rock, the rock stratum will separate and some rock blocks in every rock stratum may slide along joint surface as a whole.