在强降雨条件下，全风化花岗岩边坡岩土体饱和度增加，抗剪强度降低，易引发边坡失稳。在这一过程中，基质吸力变化是引起其抗剪强度变化的关键因素。以青岛市崂山全风化花岗岩边坡为研究对象，采用离心机试验、不排水直剪试验、X射线衍射分析、常规硅酸盐化学全分析试验和扫描电镜测试等手段，得到了基于Van Genuchten模型的全风化花岗岩的水土特征曲线，系统研究了基质吸力对全风化花岗岩抗剪强度的影响。研究结果表明：①全风化花岗岩土体饱和度与基质吸力呈负相关的趋势，级配较不均匀的土样排水能力较强；②抗剪强度指标受基质吸力的影响不同，黏聚力对基质吸力的变化相对于内摩擦角而言更加敏感；③全风化花岗岩土体中基质吸力与抗剪强度呈现正相关关系，基质吸力越大，抗剪能力越强。研究结果可为全风化花岗岩地区的边坡防治提供理论指导。

Under the condition of heavy rainfall, the rock and soil saturation of fully weathered granite slope increases, and the shear strength decreases, which is easy to cause slope instability. In this process, the change of matrix suction is the key factor leading to the change of shear strength. Taking Laoshan fully weathered granite slope in Qingdao as the research object, the soil and water characteristic curve (SWCC) of fully weathered granite based on Van Genuchten model was obtained by means of centrifuge test, undrained direct shear test, X-ray diffraction analysis, conventional silicate chemical total analysis test and scanning electron microscope test. The effect of matrix suction on the shear strength of fully weathered granite was studied systematically. The results show these as follows. The saturation of fully weathered granite soil is negatively correlated with matrix suction, and the soil samples with uneven gradation have stronger drainage capacity. The shear strength index is affected by matrix suction differently. Cohesion is more sensitive to the change of matrix suction than the angle of internal friction. There is a positive correlation between matrix suction and shear strength in fully weathered granite soil. The research results can provide theoretical guidance for slope prevention in fully weathered granite area.