The Engineering Geology And Stability Study Of Foundation In Xiamen Eastern Coastal Reclamation

In recent years, with the rapid growth of economy and population in the coastal cities, land resources shortage is getting worse. A large area of sea reclamation has become a primary means to solve the problem of shortage of land in the city. And it plays an important role in the development of coastal social economy. However, due to the high soil moisture and poor soil consolidation degree and so on a series of reasons, the land in the sea reclamation area is not conducive to engineering construction. And it is easy to cause s aseries of engineering geological problems without preoper ground treatment.On the basis of a large collection of drilling data, combined with the drilling of this exploration, the paper identified the distribution, buried depth and thickness of the major geotechnical layer in the reclamation area. Combined with the physical and mechanical index achieved by situ testing and laboratory soil test, determined the grade of the eastern reclamation sand liquefaction and partition, calculated the foundation bearing capacity in the eastern reclamation area. Meanwhile, the settlement prediction methods of soft soil foundation are discussed. The basic range of filling areas was indentified. In additon, the types of coastal zone and its sedimentation have also been found out. The main conclusions are as follows:1、in the region, the primary surfer and exposed strata are mainly composed of newly dredger fill（Q_s）, Quaternary Holocene marine layer（Q_h^m）, Alluvial-diluvial layer(Q_h^al-pl), Pleistocene Alluvial-diluvial layer(Q_p3^al-pl) and eluvial(Q^el). The bedrock is biotite granite(γ₅^3（1）b) and tuffolava which formed in late Yanshan.2、The reclamation area with relatively intense neotectonic, and the earthquake and the block rise and fall are the main forms.The earthquake intensity of the area is Ⅶ degree.3、The silt is widely distributed in estern coastal.Because of the engineering geological properties of silt, it can produce soft soil settlement under the effect of 7 degree earthquake. Therefore, it should not be as natural foundation. Meanwhile, foundation treatment measures should be adopted in the constructions in eastern coasal reclamation.4、 The dredger fill in the Eastern coastal Reclamation,which with large thickness and low mechanical strength, is saturated and fluffy. In the event of regional seismic intensity reached more than 7 degrees, it will produce sand liquefaction. Holocene Alluvial-diluvial sand layer, which is saturation, under loose-little tight station, depth and thickness vary widely. And it will produce sand liquefaction when the earthquake reached at 7 degrees. During construction, measures must be taken to reduce the impact of liquefaction of saturated sand.5、In the eastern coastal reclamation,there are many reclamation projects which distribute widely. The reclamation with long coastline and it has a tendency to expand. It will be reducing the tidal influx and strengthening the sedimentation trend. This should be valued and coordination in the planning of urban construction.