Based on the experimental results of an intact rock specimen under uniaxial compression, particle flow code (PFC2D) was adopted to carry out a discrete element modeling (DEM) for the mechanical behavior of heterogeneous rocks containing X-shaped fissures (two intersecting symmetric single fissures) under uniaxial compression. The influences of β (the acute angle between two single fissures) and the direction angle α (the acute angle between the bisector of β and perpendicular to the loading direction) on the strength, deformation, energy, crack propagation, and ultimate failure mode were analyzed in detail. Numerical simulated results showed the following: (1) Due to the X-shaped fissures, not only the peak strength, elastic modulus, crack initiation stress, and damage stress were significantly reduced, and the reduced degree of the peak strength was obviously greater than that of the elastic modulus, but also the brittleness and energy were significantly weakened. (2) The peak strength and elastic modulus generally decreased with the increase of β and increased with the increase of α . Moreover, the change trends of crack initiation stress, damage stress, boundary energy, and total strain energy at the peak stress were consistent with the peak strength. (3) Regardless of the changes of α and β , models all firstly initiated wing cracks at the two tips of the single fissure with a larger inclination angle, and the crack initiation angle decreased with the increase of the inclination angle of the single fissure. (4) The fracture was dominated by tensile microcracks, and no microcracks were generated in a certain range of the X-shaped fissure center. The failure mode was mainly split along the axial direction, and the failure surface started from the tips of the fissure and extended to both ends of models. (5) The uniaxial compressive strength and elastic modulus increased exponentially with the increase of the homogeneity factor. When the homogeneity factor was small, the microcracks were more evenly distributed in the models; when the homogeneity factor was large, the microcracks were mainly concentrated at the tips of the fissure in the models. This study can provide some references for the correct understanding of the mechanical properties of rock masses containing X-shaped fissures.

Taking the red clay of Guizhou as the test material, the moisture-heat and deformation behaviour of red clay slope under action of rainfall and illumination were studied by constructing model slopes, observation systems, artificial rainfall systems and sunlight systems. The results showed that the volume moisture content decreased continuously during the sunlight period and decreased slowly after 5 days of sunlight, but it increased sharply during the rainfall period and the increments decreased with the increase in depth. The volume moisture content of the slope crest had almost the same increments after each rainfall; the volume moisture content of the slope surface increased slightly after the first rainfall, and then increased significantly thereafter; and the volume moisture content of the slope toe increased significantly after the first rainfall, and then increased slightly. The migration of water and heat in the soil showed a strong coupling. In other words, the temperature change could indirectly reflect the volume moisture content change, and the volume moisture content change would promote the redistribution of temperature. The depth effected by everyday sunlight and rainfall on temperature were both less than 42cm. Rainfall mainly affected the horizontal displacement of the shallow soil of the slope, and the horizontal displacement of slope toe is the largest, followed by slope surface and the smallest at the slope crest.