Triaxial shear mechanical properties of weak rock coarse granular materials subjected to temperature and relative humidity

The weak rock coarse granular materials have the characteristics of high weathering degree and low crushing strength, and their mechanical properties are easily affected by the temperature and humidity environment. A series of triaxial shear tests on the weak rock coarse granular materials are carried out by controlling the temperature and relative humidity. Based on the test results, the influences of the temperature and relative humidity on the shear strength, shear deformation, particle breakage and critical state are analyzed. The results show that the mechanical behavior of the weak rock coarse granular materials is greatly affected by the temperature and relative humidity. With the increase of the temperature and relative humidity, the peak strength decreases, the shear shrinkage deformation increases, and the particle breakage degree increases. The increase of the temperature and relative humidity causes the critical state line to rotate downward in the p-q plane and to drift downward in the e-(p/p_a)^ξ plane. The influences of the temperature and relative humidity on the mechanical properties of the weak rock coarse granular materials are more significant under low confining pressures, and the differences of the test results are less significant with the increase of the confining pressure. Based on the equivalent corresponding relationships of particle breakage under different temperature and relative humidity conditions, the discrete test results of the particle breakage and critical state are transformed into the normalized results. The research results can be used to establish the constitutive model considering the influences of the temperature and relative humidity.