On-site direct shear test method of weak interlayer between rock mass layers

The invention provides an on-site direct shear test method of a weak interlayer between rock mass layers. The method comprises the following steps: Step 1, performing preparation of a specimen: Step 1-1, marking a boundary of the weak interlayer, the upper rock mass layer and the lower rock mass layer, Step 1-2, digging a first interlayer hole in the weak interlayer between the rock mass layers by taking the boundary as reference, Step 1-3, digging a second interlayer hole in the weak interlayer on one side of the first interlayer hole, and Step 1-4, completing the preparation of the specimen; and Step 2, performing on-site direct shear test on the weak interlayer between the rock mass layers: Step 2-1, completing anchor pile counterforce device assembling, and Step 2-2, completing the on-site direct shear test on the weak interlayer between the rock mass layers. The on-site direct shear test method of the weak interlayer between the rock mass layers can solve the problem of incapable on-site direct shear tes