滇西北红粘土的工程地质特性及其灾害效应

Engineering geological characteristic and geohazard effects of red clay in northwestern Yunnan,China

在野外地质调查的基础上,结合室内土工试验,系统分析了滇西北红粘土的物质组成、物性特征和工程地质特性,并以此为基础探讨了其地质灾害效应。研究结果表明:滇西北红粘土粒度组成主要以粘粒为主,粘土矿物成分比较复杂,在丽江以南其矿物成分主要以高岭石(K)为主,在丽江以北则以伊利石/蒙脱石(I/S)混层矿物为主。此外,滇西北红粘土具有含水量高、重度低、塑性高、膨胀性弱等物性特征,在天然状态下比较稳定,但是随着含水量的增加其土体强度大大降低,易引发滑坡、水土流失等地质灾害。

Based on the field geological investigation and laboratory geotechnical tests, the authors analyzed the composition, physical properties and engineering geological characteristic of red clay in northwestern Yunnan and then studied their geohazard effects. The composition analysis shows that the grain-size composition of red clay in northwestern Yunnan is mainly the clay-sized fraction. The clay mineral composition is rather complex. Usually the main clay mineral of red clay is kaolinite （K） south of the Lijiang PAver, while north of the river are iUite/ smectite （I/S） mixed-layer minerals dominant. Additionally, the red clay in northwestern Yunnan has the following physical characteristics： high water content, low specific gravity, high plasticity and weak expansibility. The red clay is stable in the natural state, but its strength is greatly decreased with increasing moisture content. Thus geohazards such as landslides and soil erosion easily occur.