侵入岩脉风化壳对中林村残积土滑坡渗流场和稳定性的影响

岩脉侵入是一种普遍的地质现象，侵入岩脉及其风化壳对斜坡的渗流场和稳定性具有重要影响，但目前国内外在该方面的研究鲜见报道。我国东南沿海约50×104 km2的白垩系火山岩地层中广泛分布侵入岩脉及其风化壳，改变了该地区残积土斜坡的失稳机制。以浙江省文成县中林滑坡为对象，研究花岗岩脉风化壳对其渗流场和稳定性的影响。中林滑坡主要由凝灰岩及其残积土组成，后部有侵入的花岗岩脉及其残积土，利用室内土柱试验获取降雨作用下两种残积土渗透性质的差异，利用不同含水率下的直剪试验获取非饱和抗剪强度参数；利用Geo-studio软件中的Seep/W模块反演土柱降雨试验，获取两种土体的非饱和渗透参数；接着将上述参数应用于中林滑坡的渗流场模拟，获取降雨入渗下坡体的渗流场；将渗流场耦合到坡体稳定性计算中，获取了坡体的稳定性变化曲线及最危险滑面。结果表明，降雨通过侵入岩脉风化壳快速入渗，并顺着基覆面向凝灰岩残积土区侧向渗流，导致侵入区与原始斜坡的交界处以及基覆面附近的地下水位快速升高，孔隙水压力迅速增大，斜坡在该位置最易变形破坏，且失稳深度远大于普通的浅层残积土斜坡，可达6～10 m。该研究成果可为东南沿海地区有岩脉侵入的残积土斜坡的稳定性评价与防治设计提供理论依据。

Impact of dyke and its residual soil on seepage and stability of Zhonglin landslide

Dyke intrusion is a relatively common geological phenomenon. The intrusive dykes and their weathered layer have great effect on the seepage field and stability of the slope. However, few studies have been reported on this aspect. The intrusive volcanic dykes and their weathered crust are widely distributed in the volcanic rocks in areas of about 500,000 km2 along the southeastern coast of China, which greatly affect the stability of the residual soil slopes in this area. In this paper the Zhonglin landslide was chosen as the object to study the impact of dyke and its residual soil on seepage and stability of residual soil slope. Zhonglin landslide is mainly composed of tuff and its residual soil and intrusive granite dyke and its residual soil which was found at the crest of a slope. Firstly, by soil column tests we obtained the difference between two types of residual soils with regard to their infiltration property and rules of two in the rainfall. Then the Seep/W in Geo-studio software was applied to retrieve soil column rainfall experiment to obtain the unsaturated seepage parameters of both types of soil to apply it to the numerical analysis of the whole slope seepage field. At last, Slope/W in Geo-studio software was used to analyze the slope stability, which revealed the impact of weathered crust of granite dyke on slope stability. The results showed that the permeability of the granite residual soil in weathered layer of intrusive dykes was better than tuff residual soil. Under the effect of weather conditions like typhoon and rainstorm, the rain water infiltrated rapidly through weathered layer of the intrusive granite dyke and flew along the strong weathered-residual soil interface into the tuff residual soil layer, which resulted in the rapid rising of the groundwater level at the junction of the intrusive granite dyke and the tuff residual soil layer and the pore-water pressure grown from negative to positive rapidly so that the slope was more likely to lose stability at this location. The results in this paper may provide theoretical background for the stability evaluation and treatment for the residual soil slope invaded by granite dykes and weathered crust in the China southeast coastal region.