清江中下游岸坡稳定性对河流地貌过程的响应

SLOPE STABILITY RESPONSE TO RIVER GEOMORPHIC PROCESS IN MIDDLE AND LOWER REACHES OF QINGJIANG RIVER

山地滑坡崩塌是岸坡演化过程中的重要地质事件,其发生发展与河流地貌过程密切相关。目前,对滑坡影响因素的研究虽多,但大多局限于滑坡本身的具体研究。通过河流地貌过程研究,进而探讨岸坡稳定性对河道变迁的响应关系,有助于更深入地认识岸坡演化规律,为岸坡稳定性的评价与预测奠定基础。本文采用自然历史分析法和类比法,结合年龄测试手段,在系统研究清江中下游古宽谷(双底谷中谷和单底谷中谷)和河流阶地的基础上,重建了河流演化和变迁的大致过程,并确定其起始时间为中更新世晚期;通过对滑坡与阶地年代对比,以及滑坡分布与不同演化河段的对应分析,发现滑坡发育的4个高峰期与4级阶地的时代较为吻合,而且对应4种演化类型河段内的岸坡稳定性具有明显的差异和规律。

Landslides and avalanches in mountains are the important geological events in slope evolution.Their e-mergencies and development are closely related to the relative river geomorphic process.Although studies on the fac-tors affecting landslide are considerable now,they are mostly limited to the landslide itself.This paper is based on studying of the river geomorphic process.It further discusses on the response relationship between slope stability and river change.The results can help us to understand the slope evolution more in-depth and to serve better to the e-valuation and prediction of slope stability.By the method of analysis of natural history and analogy,and age dating,the paper discusses the shifting and evolution of the valley in the middle and lower reaches of Qingjiang River.It is inferred that the river geomorphic process began in Late Middle Pleistocene.The inferring is according to age dating of the river terraces and comparison with adjacent area＇s terrace age and archaeological data,and based on surveying and analyzing systematically the river terraces and linear continuous distribution of the ancient valley（both bottom and single bottom valley in valley）.Through age comparison with landslides and terraces,four peaks of landslide e-mergencies are discovered according to the ages of some important landslides.They coincide with the ages of thefour river terraces.At the same time,it can be discovered that the slope stability does exist significant difference and regularity.This discovery is based on the comparison of landslides distribution and the four types of the river evolu-tion.