Research On Evaluation Method Of Ultimate Vertical Bearing Capacity Of Pile Foundation In Valley Terrains

In the valley terrain,geological and hydrological conditions is more complex. Limited bythe cost of road construction and meet the requirements of the road route, some of the bridgefoundation were constructed on slopes. The formation and development of valley terrain ismainly caused by water erosion and slope material moving.So in this region the pilefoundation inevitably be affected by water erosion.This paper discribed the vertical bearing mechanism of pile under the influence of slopesand erosion, established a overall force pile model under the influence of slopes anderosion.Then,the influence coefficients of the slope pile ultimate skin friction and the ultimateskin friction caused by lateral earth pressure after scouring were first put forward by thispaper.The influence coefficients of the slope pile ultimate skin friction considered thecoupling of slope coefficient and slope distance，and the influence coefficients of the ultimateskin friction caused by lateral earth pressure after scouringconsidered scour depth.Finally,aevaluation method of valley terrain vertical ultimate bearing capacity of pile foundation wassummed.This method have a great significance to the design,maintenance and evaluation ofthis region’s bridge pile foundation.Summarying the calculation methods of vertical ultimate bearing capacity of pile withthe effects of slope and water erosion at home and abroad,combining the vertical bearingmechanism of pile under the influence of slopes and erosion,this paper established a overallforce pile model under the influence of slopes and erosion,studies slope coefficient,slopedistance and scour depth impact on the valley terrain vertical bearing capacity of bridge pilefoundation,and summed a dynamic evaluation method of valley terrain vertical ultimatebearing capacity of pile foundation.Combining vertical bearing mechanism of slope pile,the finite difference software`sFlac3D numerical simulation is used to analyze the impact of slope on the vertical ultimatebearing capacity,the ultimate resistance at pile tip and the ultimate skin friction.Throughnumerical calculations,this paper discovers that the impact of slope coefficient,slope distanceon the vertical bearing capacity of pile foundation focus on the impact on the ultimate skinfriction. In addition,both its are coupled and positively correlated with the vertical bearingcapacity of pile foundation.As both its are smaller,as Sensitivity of the ultimate skin frictionon its are stronger.The finite difference software`s FLAC3D numerical simulation is also used to simulatethe erosion process of soil around the pile by NULL unit,and analyze the impact of erosion onthe vertical ultimate bearing capacity,the ultimate resistance at pile tip,the ultimate skin friction and the lateral earth pressure. Through numerical calculations,this paper discoversthat the impact of scour depth on the vertical bearing capacity of pile foundation focus on theimpact on the ultimate skin friction caused by lateral earth pressure. In accordance pile withhigh cap，Calculating the vertical ultimate bearing capacity of pile after scouring is notaccurate.Considering the impact of slopes and erosion on the vertical bearing capacity of pilefoundation and the vertical bearing mechanism of pile,this paper proposed influencecoefficients of the slope pile ultimate skin friction and the ultimate skin friction caused bylateral earth pressure after scouring.So through fitting the results front,this paper obtained twoformulas for the influence coefficients.Finally,this study summed a evaluation method ofvalley terrain vertical ultimate bearing capacity of pile foundation.