活动构造断裂带巨型滑坡活动特性研究——以白龙江流域大小湾滑坡为例

Analysis the activity characteristics of the giant landslide in active tectonic fault zone:a case study of Daxiaowan landslide in Bailong River Basin

白龙江流域坪定-化马断裂带内发育大量滑坡,已发生了多起重大滑坡灾害.大小湾滑坡位于白龙江左岸,为典型的活动断裂带蠕滑型滑坡.近年来受集中降雨、构造活动等因素影响,老滑坡局部出现复活迹象,处于不稳定状态.本研究通过地表变形监测、野外现场调查、遥感影像解译等,对大小湾滑坡的地质环境条件、发育特征和活动特性进行研究.结果表明,滑坡活动的整体性不明显,但分块差异性活动突出.根据运动和变形特征,将滑坡分为5个区域:中部的两处次级滑块、中部次级黄土滑坡及前缘复活的两个滑块.其中,中部的次级滑块陡坎极度发育,堆积大量基岩碎石块;临江前缘活动最为强烈,坡体破碎,裂缝发育,路面鼓胀塌陷严重.在未来的变形和运动中,前缘滑块极有可能在降雨的诱发下继续发生变形,形成滑坡堵江灾害链,严重威胁滑坡上游村镇和下游舟曲县城居民的生命财产安全,灾害风险极为严峻.

A large quantities of landslides have developed in the Pingding-Huama fault zone in the Bailong River Basin,and many major landslide disasters have occurred.The Daxiaowan landslide is located at the left bank of the Bailong River,which is a typical creep landslide in active fault zone.In recent years,affected by concentrated rainfall,tectonic activity and other factors,the ancient landslide is in an extremely unstable state with local reactivation signs.Based on surface deformation monitoring,field investigation and remote sensing image interpretation,this paper studies the geological environment conditions,development features and activity characteristics of Daxiaowan landslide.The results show that the landslide had no overall movement trend,but there are multiple blocks with different activity characteristics.Then break the landslide into five sections,i.e.,two secondary slides in the middle-upper part,one loess landslide in the middle and two resurrected slides in the front.The scarps of secondary landslides are extremely developed,and a large number of bedrock debris are accumulated on the slidebody.Significantly,the landslide adjacent to the river in the front is the most active,the surface of the slope is broken and the cracks are developed.Have more roadbed cracking,settlement,the road cracks and so on.In the future deformation and movement,the front edge landslide is likely to continue to deform under the induction of rainfall,and further form a disaster chain of landslide blocking the river,which will seriously threaten the life and property safety of the villagers in the upper reaches and the residents in Zhouqu County in the downstream.In general,the disaster risk of the landslide is extremely severe.