鄂西清江流域及其邻区地壳稳定性评价

Assessment of the Crustal Stablity in the Qingjiang River Basin of the Western Hubei Province and its Peripheral Area

地壳稳定性评价是进行重大工程建设所必须研究的课题之一。本文在分析清江流域区域构造格架、深部构造、活动断层、地震活动和现今构造应力场等影响地壳稳定性主要因素的基础上，利用模糊数学综合评判和信息量计算两种模型评价清江流域区域地壳稳定性。根据地壳稳定性４级划分标准，将该区划分为１０个稳定区，７个较稳定区，４个较不稳定区。清江干流的３级大型水利枢纽工程均位于稳定区，其库区以稳定区为主，局部跨越较稳定带。

Assessment of the crushal stability in the Qingjiang river basin of western Hubei province and its peripheral area is made using fuzzy mathematics and information models proposed as a result of investigations on neotectonic activity and seismic activity in the region. The studied area located in the middle part of the Yangtze peraplatform,is characterized by a double layered rock construction consisting of pre-Sinian crystalline basement and the supracrustal Sinian-Jarassic sedimentary cover. A tripartite tectonic framework composed of E-W-, ENE-and NW-NWN-striking faults and folds was formed in the major phase of the late Jurassic Yanshanian movement with little modification by later structural deformation.The regional investigations reveal that,aport from NWN-striking Xiannushan fault,major present active and dangerous faults and seismic zones as well as stress concentration area are distributed in Zhongxiang to the northeast, Changde to the southeast and Qianjiang to the southwest of Qingjiang river bansin respectively. They are quite far from the three dam sites,affecting them with an intensity of only Ⅳ. According to daal collected over the post four years,there are six major factors which affect the crushal stability in the region: earthquake activity, fault activity, deep-seated structures, tectonic stress fields, crushal deformation and rock porperties. This is followed by an assessment of the crushal stability of the region which are made by means of two medels,fuzzy mathematical judgement and information calculation. As a result, a zonation of the crushal stability is achieved by comparing the results of the two models: four relatively substuble subregions,seven substable subregions and ten stable subregions. It was found that the three dam sites of the mainstream of the Qingjiang river are all located in the stable subregions.