| Research has demonstrated that most slope instability disasters are closely associated with rainfall.In recent years,landslide disasters in China have predominantly occurred in the southern regions with abundant rainfall.Thus,to evaluate and predict slope stability under heavy rainfall conditions,it is necessary to accurately simulate the seepage field distribution of the slope.Typically,during heavy rainfall conditions,runoff on the slope surface is formed due to rainfall intensity surpassing the maximum infiltration capacity of the soil,which is closely related to the slope’s seepage field.Therefore,runoff and groundwater seepage under heavy rainfall conditions are interrelated and interactive.Building upon previous work,this paper proposes an improved method of rainfall boundary based on the diffuse wave approximation equation and an indirect coupling model based on the Green-Ampt rainfall infiltration model,aiming to unify the consideration of runoff and groundwater seepage.Both the improved rainfall boundary and indirect coupling model are used in combination with the local factor of safety technique to conduct hydraulic calculations and stability evaluations of the Laohuling Dam at Liangzhu City Archaeological Ruins in Hangzhou under Typhoon Lekima.The main work and the outcomes of this thesis are summarized as follows:1.This paper integrates the proposed improved rainfall boundary and the indirect coupling model algorithms into Comsol Multiphysics through secondary development.Subsequently,both models are verified in three classic experimental cases.The comparison with literature results demonstrates that the aforementioned models can accurately reflect the coupling process of runoff and seepage,enabling accurate simulation of rainfall infiltration and runoff under complex rainfall conditions.2.This study uses the Laohuling Dam at Liangzhu City Archaeological Ruins as an example to conduct basic geotechnical tests on soil samples obtained from drilled holes on site,in order to obtain relevant parameters for numerical calculations.Additionally,the microstructure of the clay is observed by scanning electron microscopy.Furthermore,point cloud data of the dam surface is obtained from 3D laser scanning to establish an accurate numerical calculation model of the Laohuling Dam.3.This study conducts hydraulic calculations and stability evaluations of the central profile of the Laohuling Dam site under concentrated rainfall conditions,using the improved rainfall boundary combined with local factor of safety technology.The hydraulic calculations reveal that the improved rainfall boundary can dynamically convert between flow boundary and pressure boundary in real-time.The stability calculations indicate that during rainfall,the safety factor of the shallow section of the earthen site decreases while the safety factor of the deep layer slightly increases.After rainfall,the safety factor of the shallow layer gradually increases,while the deep layer shows a downward trend.4.Combined with the local factor of safety technology,the indirect coupling model is employed to analyze the three-dimensional stability of the soil slope during Typhoon Lekima in 2019.By comparing the calculated results of considering runoff and neglecting it,a potentially dangerous area can be identified at the location with both the deepest ponding water depth and the maximum runoff velocity,highlighting the importance of including runoff in the analysis.In summary,each the improved rainfall boundary or the indirect coupling model,combined with the local factor of safety technology can provide an effective method to highlight the potentially dangerous positions of the shallow slope under runoff,which is of great scientific significance for the formulation of protection strategies for openair sites under heavy rainfall. |
