Research on landslide’s original rock structure characteristics and evolution model of the Huangtupo landslide in the Three Gorges Reservoir area

The Huangtupo landslide in the Three Gorges Reservoir area is a large compound deformable body, and its evolution model needs to be further examined. Data of investigation of the Huangtupo landslide and the Baitupo deepmonitoring borehole core data are analyzed by comparison in this paper and it is found that the weak interlayers in the upper submember of the third member of the Badong Formation have developed more densely than those in the lower submember, and interpenetrant interlayers have developed in the sliding bed of Huangtupo landslide. Interlayers have been mudded into the type of gravel clay. The original rock structure of the Huangtupo landslide is recovered according to the weak interlayers’distribution characteristics in the third member of the Badong Formation, from which it can be concluded that the Huangtupo landsilde is the product of many times’sliding of compound retrogressive landslide. Because interlayers have developed densely and are easy to be mudded into sliding zone in the upper submember rockmass of the third member of the Badong Formation, the front of the Huangtupo slope cut by F3 and broken by subsidiary fold fault is likely to slide after deep-seated creep in advance. The weathered and broken rockmass of lower submember of the third member of the Badong Formation in the middle of the Huangtupo slope slided (or falled over) and overlaped on the slumped mass in the front of the Huangtupo slope. Finally, the Garden landslide occurred and pushed the surface weathering broken rock of the second member of the Badong Formation in the back of the Huangtupo slope to overlap on the middle rockmass of the Huangtupo slope. Affected by the Three Gorges Reservoir’s impoundment, the deep creep of slumped mass and deep interlayers of the Huangtupo landslide will further intensify. This evolution model can explain the cause of formation of the complicated sliding structure in the Huangtupo landslide and its change.