| In December 20,2015,a catastrophic landslide occurred in Shenzhen,Guangdong,Southeast China.Seventy-seven people were killed,and 33 buildings were buried or damaged,which were in the direct path of the landslide at the Guangming New District.The landslide involved 2.75 million m3 of the municipal solid waste(MSW)and had a horizontal runout distance of 1100 m.This was equivalent to the angle of reach(fahrb?schung angle)of 6°.This landslide is one of the most serious landfills landslide in the world.This paper studies the failure mechanism,long run-out mechanism and disaster mode of the large artificial landfill landslide.Through the research,the main conclusions and results are obtained as follows:(1)Through field investigation and in-situ test,this slope are divided into five stages in the artificial loading process before slope failure,and it is considered that the Shenzhen landfill slope structure has the special binary structure characteristics of a fully rolled front slope and the rear slope with loose soil.The multi-level dynamic loading model and the landslide zoning accumulation model are established.(2)The physical and mechanical properties of the sliding soil were tested systematically,and the main components of the artificial landfill slope were analyzed by the in-situ window test.The in-situ test shows that the residual soil has the characteristics of low compaction,high moisture content and low shear strength.Laboratory triaxial tests and ring shear tests revealed the CDW mechanical mechanism of static liquefaction action under excess pore water pressure in failure stage and the water lubricating physical effect to CDW in motion stage.(3)Based on the difference material properties under binary slope structure,the numerical simulation method of fluid-solid coupling was used to analyze the distribution of groundwater seepage field and the evolution process of slope stability in different loading stages.The analysis shows that the high pressure head of the front slope and the static liquefaction phenomenon of the rear CDW soil together lead to the surface of the rupture formation of landslide.The failure mechanism of artificial landfill slope was stability decrease of the front slope and the rear soil driven by the static liquefaction under the groundwater seepage and CDW loading.(4)Through undrained ring shear test and chute physical model test,the mechanism of long run-out fluidization movement of artificial landfill landslide was analyzed.The three types of long run-out fluidized landslide under different moisture content of landfill slope was put forward.The three types of flow lanslide reveal the dynamic transformation process of landslide from rapid sliding to flowing during the process of movement.The dynamic transformation process of flowslide from rapid sliding to flowing is revealed.(5)Through the landslide dynamic analysis method based on SPH,the dynamic process of landslide in Shenzhen was reconstructed accurately.The model of "static liquefaction instability,boundary layer liquefaction sliding and fluidized movement accumulation" of Shenzhen landfill landslide was established.The results showed that a combined FB(frictional-Bingham)model and parameters provided the best performance in simulating landfill landslide with high moisture content.(6)Based on the causes analysis of landslide disaster,this paper summarizes the risk problems existing in the construction process of artificial landfill slope,and put forward effective risk prevention and control measures from the aspects of diversion and drainage system,emergency plan,construction scheme and scientific site selection,etc. |
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