| Guizhou province is located in the plateau slope,which transitions from Yunnan-Guizhou Plateau to the low hills of the east.The region is also a karst plateau rising between Sichuan Basin and Guangxi Hills,and is characterized by complex geological structure and widely distributed karst strata.Unlike the karst peak-cluster and peak-forest landform composed of carbonate rocks in Guangxi,the karst and non-karst strarum are alternately distributted in Guizhou.The geological processes in the study area such as the tectonic stress field,groundwater migration field,weathering and unloading of the rock mass all show strong regional characteristics.Fold and fault structures are well developed,and often form the place with the geological hazards of karst and rock slide-debris avalanche.The study area is a karst area with prominent fragile and continuous characteristics.Due to the frequent human activities such as mining and infrastructure construction,Guizhou has become one of the most common areas of landslide and rock fall in China,resulting in casualties and substantial property loss.In this paper,based on the comprehensive investigation of geological disasters and the division of disaster causing modes in Guizhou,the “key block” control type landslide-debris avalanche,the “key block” control type landslide-water wave and the“goaf” control type rock fall-debris avalanche that caused mass casualties in the karst area have been analyzed.Based on the field investigation,UAV video,seismic signal,high resistivity tomography(ERT)method,and numerical simulation,the Guanling landslide-debris avalanche,Shuicheng landslide-debris avalanche,Fuquan landslide-water wave,and Nayong rock fall-debris avalanche were taken as examples to research the movement process,dynamic behaviors,and deposit characteristics of typical events.In addition,the Jianshanying geological potential hazard was investigated to predict the runout distance of a “goaf” control type landslide.The main innovations in this study are as follows:(1)The disaster-causing mechanism of typical landslides and associated debris avalanche and water wave in Guizhou have been firstly investigated based on the analysis of the development modes and disaster causing modes of landslides and avalanches.The development modes of landslides are divided as “weak plane” control type,“key block” control type,“goaf” control type,“soft foundation” control type and“multiple” type landslides.Notably,the Guanling landslide,Shuicheng landslide and Fuquan landslide are typical landslides with “key block” control type.Also,the development modes of rock avalanche are divided as “soft foundation” control type,“weak plane” control type,and “goaf” control type,and the Nayong rock avalanche is the avalanche with “goaf” control type.The disaster causing modes of typical geological disasters in Guizhou were divided as “landside-debris avalanche”,“rock fall-debris avalanche”,and “landslide-water wave”.Combined with typical cases,the work conducted in this study detailed analyzed the disaster causing process and failure mechanism of these three types of disaster causing modes.(2)The Guanling landslide and Shuicheng landslide were selected to investigate the whole runout process of the “key block” control type landslide.The DAN3 D models of the Guanling landslide and Shuicheng landslide were established based on the detailed field investigation and DEM data.Suitable rheological models and parameters were determined through the trial-and-error analysis,and the dynamic characteristics and runout behaviors of these two cases were simulated.The ERT method was performed on the Guanling landslide to investigate the spatial characteristic of the deposits and verified the validity of DAN3 D simulation results.The method combined the DAN3 D and ERT method provided a valid approach for the analysis of landslide deposits and revealed the disaster-causing mechanism of a landslide with the “key block” control type.(3)The Nayong rock avalanche was selected to investigate the whole runout process of the “goaf” control type rock avalanche.The triggering process of the Nayong rock avalanche was analyzed based on the UAV video and seismic signal,and the combined analysis of UAV video and recorded seismic signal provided a new method for the dynamic analysis of a specific rock avalanche.Also,the rheological models and parameters for the numerical simulation were determined based on the trial-and-error method,and the runout behavior of Nayong rock avalanche was investigated based on the DAN3 D.The simulation results of DAN3 D were examined by the analysis results of the seismic signal.The work conducted in this study revealed the disaster-causing mechanism of the debris-avalanche with the “goaf”control type and provided a new method to analyze the dynamic characteristics of a rock slide-debris avalanche.(4)The whole runout process of the landslides with a “weak plane” control type was analyzed in this study.The DAN3 D model was used to simulate the movement process of the Fuquan landslide before running into the water.Also,the shape andvelocity distribution of the sliding mass at different time steps were analyzed.Based on the characteristics of the landslide before entering the water,the numerical models and parameters of water wave were determined.The software FLUENT was selected for the numerical simulation of the movement process of debris avalanche entered into the water and the associated water wave.Afterward,the maximum dynamic pressure and the movement distance of the sliding mass at different time steps were obtained,and the disaster-causing mechanism of a landslide-water wave of “key block” control type was revealed.(5)The prediction method of the runout distance of a “goaf” control type potentially risky site was summarized in the study.The DAN3 D was used to predict the movement process of Jianshanying geological potential hazard based on the rheological models and parameters obtained through multi-source data collaboration.Also,the simulation results were compared with the results of the empirical formula.It is expected that the method performed in this study could provide a new approach for the risk assessment of potential geological hazards in Guizhou. |
PDF Full Text Request