The Research On Stability Of Pile Foundations In A Construction Site In Tangshan City

China’s coastal areas are the underground karst area and the development area,Hebei is one of the important provinces that karst collapses happen in north of China,these areas are mainly distributed in the urban area of Tangshan and Liujiang River basinof Qinhuangdao, Western Xingtai there are sporadic occurrence. Because of theearthquake of1976in Tangshan, which caused the stress redistribution, the karst collapseinfluence range extended to20km2, and it caused great harm to Tangshan city’s economicdevelopment and infrastructure.Now as to city construction in China, more and more buildings and structures haveto be constructed in the karst area. Karst area has a very important influence on the pilefoundation bearing capacity and settlement, such as the cave may affect the pile soilaround the pile and pile friction; the cave at the bottom of the pile and the thickness maybe due to lack of roof, in the upper load under the effect of crushing the roof, resulting inloss of bearing capacity of pile, and thus a threat to the stability of the upper structure.Therefore the underground karst on the pile foundation design and construction has amajor impact.There are some more shallow buried of the Ordovician limestone rock and somekarst cave under the Quaternary overburden layer in the area of Tangshan.Under theinfluence of structures’ load, the underground void is likely to deform collapse, cause thefoundation’s deformation, thereby affect structures’ regular service, and may even causethe accident, based on the site specific geological conditions as the basis, the simulationpile foundation of pile and soil stress field and displacement the fields. We can learn thatfrom the analysis of the bearing capacity of the pile foundation in the karst area,economic and effective solutions can be obtained, so that to provide the basis for theengineering design and construction will also be provided.Therefore, the study of foundation stability is benefit to the use of land and infrastructureconstruction in our country.