三峡库区巫山县城二郎庙小区岩溶引起的地质灾害危险性研究

Risk of geohazards caused by karst processes in the Erlangmiao area,Wushan County,Three Gorges reservoir region

三峡库区移民迁建中发现的岩溶问题是一个重大工程地质问题。巫山县新城二郎庙小区是地质灾害监测预警示范区,那里的三叠系嘉陵江组灰岩在特殊的气候、水文和地质环境下遭受了强烈的岩溶作用,岩体结构变得非常复杂,完整的灰岩变为层状碎裂岩体、岩溶角砾岩、泥质条带和残坡积角砾层。不同的地貌部位具有不同的岩溶特点和强度,总体规律性是由西向东、剖面下部至上部岩溶作用增强,其中陡坡下地形由陡变缓的转折地带和冲沟下部是岩溶作用最强烈的地带。岩溶作用形成了各种微地貌和特殊的岩体组合格局。岩溶导致岩体的力学强度和稳定性不断降低,加上其他自然因素和人为因素作用可能产生地面不均匀沉降、地裂缝、滑坡、崩塌、泥石流和地面塌陷地质灾害,这些问题必须在移民迁建以及将来城镇运行过程中引起高度重视。

Karst recently discovered during relocation of migrants in the Three Gorges reservoir region is an important engineering geological problem. The Erlangrniao area in the new city of Wushan County is a geohazard monitoring and early-warning demonstration area. In the area, limestone of the Triassic Jialingjiang Formation underwent strong karstification due to the special climatic, hydrological and geological conditions, so the rock mass structure becomes very complex and massive limestone has been turned into layered, fractured rock masses, karst breccia, argillaceous bands and eluvial breccia layers. There are different features and intensities of karstification in different geomorphological zones. Generally, karstification increases from west to east and from the bottom of the section upward. Among other things, the zones of transition from the steep to gende topography and the lower part of gullies are the strongest karstification zones. Karstification gave rise to an assemblage framework of various microlandforms and special rock masses. With karstification, the mechanical intensity and stability of rock masses decrease progressively, which, together with other natural processes and human activities, may cause geohazards such as uneven subsidence, ground cracks, landslides, avalanches, mudflows and ground collapses. Great attention must be paid to these problems in the process of migrants resetdement and future town construction.