Reactivation mechanism of a large-scale landslide deposit in Nanchuan District, Chongqing, China

This is the authors' abstract. We don't add key points for this paper.

In karst mountainous areas, numerous landslide deposits are prevalent, understanding the mechanism behind the reactivation of large-scale landslide deposits (with volumes exceeding 10 million m³) remains ambiguous. A case study was conducted focusing on a prominent example in Nanchuan District, Chongqing, China, specifically the Toudu Landslide Deposit (TLD). This study identified its triggering factors through various geological survey methods, including field investigations, drilling engineering, data monitoring, and SBAS-InSAR remote sensing interpretations. Furthermore, PFC2D numerical simulation is employed to illustrate the evolution process of its reactivation. The research findings indicate that, through the combined influence of natural rainfall and artificial irrigation, the TLD experienced reactivation. Surface deformation manifested in distinct zones of strong and weak deformation, with a spatial pattern characterised by “small in the middle and large at both ends” within the strong deformation zone. Additionally, multiple slide surfaces were observed in the subsurface deformation. Furthermore, there exists a synchronous consistency between subsurface and surface deformation, albeit with a certain degree of lag in subsurface deformation, ultimately leading to the cracking of residential buildings and roads in the rear of the TLD.