峨眉山玄武岩岸坡深部差异风化岩体特征及成因  

Characteristics and formation mechanism of deep differential weathering rock mass in Emei Mountain basalt canyon slope

作　　者：韩刚[1,2] 赵其华[1,2] 彭社琴[1,2] 

机构地区：[1]地质灾害防治与地质环境保护国家重点实验室(成都理工大学) [2]成都理工大学环境与土木工程学院,四川成都610059

出　　处：《岩土工程学报》2011年第10期1547-1553,共7页Chinese Journal of Geotechnical Engineering

基　　金：国家自然科学基金项目(40772177);国家重点基础研究发展计划(973)项目(2011CB013501);长江学者和创新团队发展计划项目(IRT0812)

摘　　要：西南地区某水电工程的峨眉山玄武岩,其岩体风化具有特殊性,存在岸坡内部(或深部)岩体风化局部加强的特殊现象(称为差异风化)。该差异风化岩体在表观特征、分布特征、化学特征及形成环境上具有与岸坡表部一般风化岩体不同的显著特征。以该处差异风化岩体发育分布规律为基础,结合其化学特征、河谷演化过程及浅生改造理论分析其成因机制。研究表明:差异风化不具随水平深度增大风化逐渐减弱特征,分布受长大张性结构面控制,表现为局部的裂隙式风化加剧,张性结构面两侧5～15 cm范围内岩体红度增加;差异风化岩体发生了化学风化,但并未发生明显的脱硅富铝与盐类淋失迁移,仅表现为二价铁减少、三价铁富集;控制性结构面具浅生改造特征,差异风化岩体赋存于浅生结构所形成的相对封闭空间;浅生改造正是导致差异风化岩体形成的根本原因。The Emei Mountain basalt of a hydropower project in the southwest of China is special in its weathering characteristics.There exists abnormal weathered belt inner rock mass（called differential weathering）.Differential weathering is much different from normally weathering rock mass in its apparent,distribution,chemical characteristics and environment involved.The distribution characteristics of differential weathering rock mass are analyzed.And the formation mechanism is studied by analyzing chemical characteristics,valley evolution and near surface action theory.The main conclusions are drawn that the differential weathering does not weaken with the increase of the horizontal depth.The distribution is controlled by long tension fracture,and highly weathered near fracture.It is much redder within 5~15 cm of the tension fracture.Chemical weathering occurs in differential weathered rock including decrease of Fe 2＋ and increase of Fe 3＋.But there is no obvious decrease of Na,K,Ca,Mg,Al and Si.The controlling discontinuity appears near surface action characteristics,and differential weathering rock mass is formed by near surface action.

关 键 词：峨眉山玄武岩 差异风化 化学特征 浅生改造 成因机制 

分 类 号：P642.24[天文地球—工程地质学]