长江江西段岸坡崩塌及其对防洪大堤的影响

BANKSLOPE CAVING AND ITS INFLUENCE ON THE FLOOD BANK IN JIANGXI SECTION OF THE YANGTZE RIVER

长江河道江西段原在湖北的龙感湖至安徽的大白湖一带。由于秦岭一大别山的不断隆升,扬子地块发生沉降,构造掀斜,加上科氏力的共同作用,加剧了河道变迁进程。经过漫长的历史演变,河道不断侵蚀右岸,呈蛇曲状向南摆动,现已迁至江西境内,河道由北向南移动了20余km。长江江西段江岸79.75％为第四系松散堆积物组成的易冲刷岸带,6.67％为第四系、基岩组成的岩土混合较易冲刷岸带,13.59％为基岩组成的耐冲刷岸带。由于第四系堆积物组成的江岸分布广,造成江西江岸的极不稳定,岸坡崩塌分布相当普遍,严重影响了防洪大堤安全。通过实地走访调查.并查阅前人的工作成果和历史资料,对江西长江岸坡崩塌的发育规律及其对防洪大堤的影响进行了分析和论述。

The Jiangxi section of the Yangtze River, situated from Longgan lake of Hubei province to Dabai lake of Anhui province, was aggravated by Qinling-Dabie mountains uplifting all the time, massive sedimentation, tec-tonic tilting and kesi force action,It has undergone a long historical evolution,has swung more than 20 km from north to south by erosions in the right bank, and moved into Jiangxi. 79.5% of its bank is the bankbelt accessible to erosion, composed of quternary loose oleoposits, 6.67% of its bank in the section is the bankbelt more accessible to erosion, made up of quternary Qeposists and bedrock mix, and 13.59% of its bank is the bankbelt standing up to erosion, made up of bedrock. The bank which is composed of quternary sediments is widespread, resulting rather wide bankslope cavings . On the basis of a lot of field surverys and reference to the fruits of forerunners' achievement and its historical dates, the authors analyze and discuss more systematicly devoloped pattern of the bankslope caving and its influences on the flood bank in Jiangxi section of the Yangtze River.