降雨入渗是诱发边坡失稳的主要因素之一。基于有限体积法和离散元法耦合的建模方法，建立了降雨条件下含砾花岗岩残积土边坡的数值计算模型，并通过与室内边坡模型试验进行对比，验证了数值模型的可靠性，采用数值计算模型分析了降雨入渗作用下，不同砾石含量对含砾花岗岩残积土边坡稳定性的影响，研究了颗粒位移场、转动场、接触力链、组构各向异性等的变化规律。结果表明：在降雨入渗作用下，砾石含量为0和25%时滑动面为圆弧形滑动，50%时为流动形滑动；随着砾石含量增加接触长力链逐渐减少，接触短力链逐渐增加，接触力之间的连续性减弱，传递应力的主体接触类型由土-土接触转为土-石与石-石接触类型；边坡颗粒间接触各向异性程度在降雨过程中呈动态变化，并在砾石含量增至75%时出现显著提升；边坡的稳定性随着砾石含量先降低后上升，在砾石含量达到75%时，边坡的稳定性明显提升。

Rainfall infiltration is one of the main factors inducing slope instability. Based on the modeling method coupled with finite volume method and discrete element method, a numerical calculation model of gravelly granite residual soil slope under rainfall condition was established, and the reliability of the numerical model was verified by comparing with the indoor slope model test. The numerical calculation model was used to analyze the influence of different gravel contents on the stability of gravelly granite residual soil slope under rainfall infiltration, and to study the change rules of the particle displacement field, rotation field, contact force chain, constitutive anisotropy and so on. The effect of different gravel content on the stability of gravelly granite residual slope under rainfall infiltration was analyzed by numerical modeling, and the variation rules of particle displacement field, rotation field, contact force chain, and structural anisotropy were studied. The results show as follows. Under the action of rainfall infiltration, the sliding surface is circular sliding when the gravel content is 0 and 25%, and it is flowing sliding when it is 50%. With the increase of gravel content, the contact long force chain gradually decreases, the contact short force chain gradually increases, and the continuity of contact force decreases, and the contact type of the main contact that transmits the stresses is changed from soil-soil contact to soil-rock and stone-rock contact type. The contact anisotropy of slope particles shows the same pattern during the rainfall process, and the degree of contact anisotropy is also changed in the rainfall process. The degree of contact anisotropy between slope particles changes dynamically during rainfall and increases significantly when the gravel content increases to 75%. The stability of the slope decreases and then increases with the gravel content, and the stability of the slope increases significantly when the gravel content reaches 75%.