温度降雨耦合方式与构造活动对黄河上游巨型滑坡的触发与控制

The landslide triggering mechanism is a hot and focus issue in the current geological disasters research, and of great significance to the disaster prevention and geological environment safety. The giant landslides are characterized by cluster, concentration, seriously harm and mechanism complexity in the section from the Sigouxia gorge to Laganxia gorge in the upper reaches of the Yellow River. The strong seismic and fissures may trigger the landslides due to active tectonic development. Increased snow melt water in the upstream caused by elevated temperature may lead the strengthened river erosion and the development of large free slope surface to cause the occurrence of giant landslides. Therefore,the coupling patterns between active tectonic, landform development, configuration of temperature and rainfall dominated the development of giant landslide in the region. In this study, The macro and micro ways, such as field anatomical survey, rock and soil sample test, the paleo-climate and paleo-landform reconstruction and numerical simulation, will be used to analyze the dynamic mechanism of giant landslides. 1) To reconstruct the sequence of temperature and rainfall since the last glacial period and then to identify the coupling relationship between temperature, rainfall and giant landslides; 2) To simulate the triggering development of giant landslides caused by river erosion and landform evolution; 3) To investigate the spatial distribution and the characteristics of fissures along the Jishishan fault and their relation with giant landslides；4) to analyze the key controlling factors of giant landslides and develop a typical model of development of giant landslides.

滑坡形成机理是目前地质灾害领域研究的热点和难点，其对灾害防治和地质环境安全具有重大意义。黄河上游寺沟峡--拉干峡段巨型滑坡具有群发、集中、危害严重、机理复杂等特点，这里活动构造发育，其直接引发的地震和控制的地裂缝都与滑坡存在成因联系；同时不仅集中降雨会直接触发滑坡，因升温造成上游冰雪融水增加，加强河流下切、形成临空面而诱发巨型滑坡，因此活动构造、地貌演化和温度降雨之间的耦合关系是解析该区巨型滑坡关键所在。项目拟通过野外调查、岩土体测试、古环境重建、数值模拟等多种手段，开展区内巨型滑坡与温度降雨变化、强震活动、地貌演化及岩土体结构之间耦合关系及主控因素研究。重建末次冰期以来的温度降水演化序列，查明二者之间的配置关系及对巨型滑坡的诱发机理；模拟河流侵蚀、阶地形成的地貌演化过程对滑坡的触发作用；调查沿积石山断裂展布的地裂缝带空间展布和性质及其与巨型滑坡间关系；厘定区内巨型滑坡发育的主控因素。

滑坡形成机理是目前地质灾害领域研究的热点和难点，其对灾害防治和地质环境安全具有重大意义。黄河上游寺沟峡--拉干峡段巨型滑坡具有群发、集中、危害严重、机理复杂等特点，这里的活动构造、地貌演化和气候变化之间的耦合关系是解析该区巨型滑坡关键所在。项目通过野外调查、岩土体测试、古环境重建、数值模拟等手段，在区域上开展了滑坡时空特征及对气候变化的响应研究和青藏高原东北缘共和-贵德盆地全新世气候变化研究；典型巨型滑坡方面，研究了夏藏滩巨型滑坡形成机制与演化过程、席芨滩巨型滑坡发育特征及地貌演化、松坝峡特大型滑坡堰塞湖及地貌效应、二连泥流扇成因及地貌演化过程以及夏藏滩滑坡湖湖相沉积粒度特征及古环境意义，厘定区内巨型滑坡发育的主控因素。主要取得了以下重要认识：1）黄河上游巨型滑坡从时间尺度可划分5个主要发育期，分别为53-49ka B.P.、33-24 ka B.P.、10-8ka B.P.、5-3.5ka B.P.和现代；2）青藏高原东北缘在58～50ka B.P.和30～15ka B.P.两个时期为多雨湿润期，这两个时期也是该区巨型滑坡的频发期，从时间对应关系看，研究结果可能指示了在传统的冷阶段该区较湿的气候条件；3）黄河上游的巨型滑坡多呈多期次演化模式，构建了典型巨型滑坡演化模式，分析了贵德盆地东部晚更新世以来地貌演化时间顺序和滑坡群发育的时间先后顺序；4）建立了青藏高原东北缘大气粉尘的风力强度指数、粉尘搬运距离指数、大气湍流强度指数、春季近地面气温指数和有效湿度指数等估算方法。