The results of the samples with three different types of infilled joint soils (mud with fragment

mud with sand and muddy) and the ones with three different water contents (10%

7% and 3%)around the in-situ water content by the reversal direct shear tests (normal stress is between 2 MPa and 10 MPa) and particle size distribution (PSD) tests (around the shear zones) were compared to get the effects of the different initial particle size distributions and water contents on the infilled joint soil. Some conclusions are drawn as follows. ①The degree of particle crushing is higher quantified by Br index (relative particle crushing potential) for the coarser particles (d60 is greater). ② Dry particles (lower water content) tend to crush to tiny particles due to abrasion and wet particles (higher water content) generate more relative large particles due to fracture or attribution. ③ Coarse particles have limited effect on the peak strength; besides nonlinearity of residual strength envelope is higher for coarser particles(d60 is greater). ④ Cohesion and friction angle decrease linearly with water content; moreover the samples with lower contents have a higher nonlinear residual strength envelope. ⑤ The residual friction angle decreases linearly with clay fraction; in addition

the equation proposed could be used to estimate the residual friction angle of the infilled joint soils preliminarily in practice.