| In recent years,tons of large-scale high-speed rockslides occurred around the world.High-speed rockslides in different regions manifest as various deformation and failure characteristics,especially the kinematical behaviors,including impact,fragmentation,friction and shear failure during the movement,which are extremely complex.Additionally,landslide deposits are relatively susceptible to reactivate by external triggers and form potential secondary disasters.The existing research indicate that large-scale high-speed rockslides are conventionally triggered by serious tectonic activities or short-term extreme precipitation,while there are only a few of such large slides directly induced by anthropological activities,which are extremely catastrophic and destroyable to the safety of infrustuctures and residents.The research about the formation mechanisms of such large-scale rockslides induced by unreasonable engineering activities is limited.The large-scale catastrophic high-speed rockslides,named the WZL,with two open-pit mining quarries,located in Xingyang Village,Jiuli Town,Emeishan City,Sichuan Province,which activated in 2011 and then reactivated in 2015.In the study area,serious disturbance caused by long-term high-frequency production blasting,which seriously degrade the rock mass.In 2011,about 3.0×106 m3 rock mass suddenly slide,blocking the front river with landslide dam and forming a barrier lake.In 2015,with the evolution of natural environment,a total of more than 6.0×106 m3 strongly deformed mass suddenly detached from the original slopes and slide along the underlying rupture surface on the north direction and formed a landslide dam again.According to the detailed geological investigation and analysis,the rockslide is different from the seismic landslide as well as rainfall-induced landslide,which is mainly triggered by the artificial blasting vibration and excavation.With the special stratum combination and unique slope structure,the landslide has distinctive features in terms of formation mechanism,failure mode,and run-out process.Many of the extraordinary kinetic phenomena that occur in the rockslide are spectacularly displayed by the WZL,which is valuable to be further investigated.For analyzing the complex formation mechanisms of large-scale high-speed rockslides triggered by unreasonable anthropological engineerings,the WZL was taken as a real case study.Based on its geological setting of original slopes,strength parameters of rock mass,triggering factors,et al.,from Pre-failure statges,failure stages,until post-failure stages of landslide process,the deformation chracteristics,failure mode as well as runout are comprehensively analyzed.With the ultilization of in-situ geological investigation,physical experimental testings,numerical modellings,data mining based on artificial intelligience,the research gap of large scale high-speed rockslides has been narrowed,which gives valueale suggestions to risk mitigation for this kind of hazards.The research cover the scope of engineering geology,geomorphology,sedimentation,computational mechanics,engineering mechanics,and artificial intelligience techniques,the main research results and innovations can be concluded as follows(1)The WZL is developed in the slope with gentle inclined bedding structures,which mainly consisting of upper Permian Emeishan group basalt(bedrock)and volcanic tuff(weak intercalation).Based on the preliminary analysis,the WZL is a composite rockslide consisting of two different high-speed rock mass movements,which were triggered by open-pit mining activities with devastating effect in 2011.Then,it was reactivated by heavy rainfall in the monsoon season after 4 years.The failure modes of these two event are inconsistent.Due to the two blasting areas,the first landslide performed as a retrogressive consequent bedding slide mode,which envolved from creeping,rear tensile cracking,and shear failure along the rupture surface.In 2015,the landslide reactivated and performed as an advancing consequent bedding slide mode,which envolved from initial sliding,tensile cracking,and planar shear failure.The key block to prevent mass sliding is the "composite resistant block",which consists of frontal locking part of the sliding surface and the rear tail of previous landslide deposits.(2)The influencing factors of the WZL include:production blasting vibration,engineering excavation,hydraulic forces,special terrain,and slope structure.The production blasting is the main factor.The disaster formation mode of WZL consists of five stages:natural evolution of slopes,deformation and failure caused by local production blasting and excavation,high-speed landslide and debris avalanches(landslide in 2011),creeping of rear tensile deformation mass,reactivation of landslide(landslide in 2015)(3)Based on the field investigation of production blasting on the slopes,with the Finite Difference Model(FDM)dynamic numerical simulation technology,the dynamic fracture mechanism of rock under blasting impact load,the internal damage of the weak interlayer,and the dynamic response of the slope structure are discussed.The maximum principal stress and fracture energy of the slope are calculated and analyzed,and the dynamic expansion of the joint crack of the rock mass and the cumulative damage of the blasting vibration of the weak interlayer are proposed.The cumulative damage factor D of weak interlayer is proposed here The internal fracture deformation mode of rockslide is analyzed.The initiation mechanisms of post-blasting landslide is summarized as four stages(4)Through the programing of Material Point Method(MPM)calculation code,the multi-field variation of the WZL in 2011 and in 2015 is comprehensive studied.For the two distinct sliding,the vector alternations of stress,strain invariant,velocity and displacement of the different sliding mass during the run-out process from the initiation,deposition,reactivation,to re-deposition was captured.The kinematics and formation mechanism of landslides is analyzed.(5)Based on the theory of machine learning,the modified particle flow code is proposed for studying the landslide kinematics and mobilization in three-dimensional scale.The artificial intelligence algorithm is the first time to be used to calibrate and identify the microscopic parameters which is needed in the numerical simulation of PFC3D,and the optimal prediction model of the connection between macroscopic parameters and microscopic parameters of rock is established here.The three-dimensional distribution,internal bond fracture,velocity zoning characteristics of the rockslide as well as lateral debris avalanches are reproduced by the hybrid modelling techniques.Furthermore,the disaster mechanisms of the rockslide movement as well as risk subzones is further analysed. |
