陕西宝鸡市三趾马红土工程地质特性及灾害效应  

Engineering geological properties and hazard effects of Hipparion laterite in Baoji,Shaanxi Province

作　　者：李滨[1] 吴树仁[1] 石菊松[1] 冯振[1] 

机构地区：[1]中国地质科学院地质力学研究所/国土资源部新构造运动与地质灾害重点实验室,北京100081

出　　处：《地质通报》2013年第12期1918-1924,共7页Geological Bulletin of China

基　　金：国家自然科学基金项目(批准号:41102164);国家科技支撑项目(编号:2006BAC04B02;2012BAK10B01和2012BAK10B02)

摘　　要：陕西宝鸡市渭河北岸地区厚层黄土底部普遍存在一套三趾马红土，其物理力学特性控制着滑坡灾害的发生。通过试验分析发现：①三趾马红土粘粒含量高（一般在37％～55％之间）、蒙脱石或伊利石／蒙脱石类膨胀性粘土矿物含量大（相对舍量55％～75％，绝对含量21．99％～33．98％）、有效蒙脱石含量为18．61％～27．56％，比表面积平均值为204．7m2／g，最高达262．9m2／g，属于膨胀性粘土，物理化学活性强；②三趾马红土微裂隙发育、胶结程度差、易崩解，天然状态下为坚硬粘土，饱水后呈现可塑-软塑态．具显著膨胀性；（彭三趾马红土的天然强度相对较高，而遇水饱和后，粘聚力和内摩擦角明显降低，峰值强度和残余剪强度降幅在47％～63％之间。因此，三趾马红土在地下水作用下强度显著降低，成为高陡斜坡中的软弱地层，形成剪切带，控制着渭北黄土塬边地区滑坡的发育与分布。Hipparion laterite extensively exists at the bottom of thick loess on the northern bank of Weihe River in Baoji, Shaanxi Province, and its physical and mechanical properties control the occurrence of landslide hazard. Through test analysis, the authors have reached some conclusions： ①Clay content of Hipparion laterite is high （generally 37%～55%）, so is the content of expansive clay minerals, such as smectite and smectite/illite （the relative content is 55%～75%, and the absolute content is 21.99%～33.98%）. Ef fective smectite content is 18.61%～27.56%, and the mean value of specific surface area ranges from 204.7m2/g to 262.9m2/g. These data indicate that it belongs to expansive clay and it is physically and chemically active;②The Hipparion laterite is characterized by pre-existence of microfissures and poor cementation as well as easy disintegration. It is gumbo under natural state, but presents plastic/soft plastic state when saturated and significant expansibility; ③Natural intensity of Hipparion laterite is relatively high. Its cohesion and internal friction angle are reduced obviously when it is saturated, and the decreasing amplitude of peak intensity and residual shearing strength is 47%～63%. Therefore, the strength of Hipparion laterite will be reduced obviously under the effect of underground water; and it will turn into weak strata on high and steep slope and form the shear zone to control the development and distribution of landslides in loess tableland area of Weibei.

关 键 词：三趾马红土 物质组成 微观结构 物理力学特性 滑坡 

分 类 号：P642[天文地球—工程地质学] P694[天文地球—地质矿产勘探]