Study On The Technology Of Foundation Treatment And Settlement Effect Of Reclamation In Offshore Beach

With the accelerated pace of economic development in coastal areas,the relationship between supply and demand of urban land is becoming increasingly tense,and reclamation of land from the sea can increase the urban land area for a short time,this method has been widely used.However,in the engineering practice,the stability and reliability of the reclaimed soft foundation are often affected by various factors.At present,there are few researches on the consolidation of the reclaimed soft foundation in the coastal area but most demonstrations on the settlement effect after the practical engineering.So the study on the technology of foundation treatment and consolidation settlement of reclamation in offshore beach has important effect on the economic development in coastal areas.Based on the sea reclamation engineering of Xiamen Xiang'an new airport which was seated in DaXiaoDeng island,the research progress and future development trend of foundation treatment methods at home and abroad were introduced.The advantages and disadvantages of the consolidation mechanism of replacement method,stack preloading and vacuum preloading method were discussed.Considering the factors such as construction and cost,the corresponding method of foundation treatment was selected in different positions of the airport.Secondly,combined the finite element method of numerical simulation with field exploration data,this paper analyzed the rapid filling technology on tidal flat and the process of consolidation settlement.Finally,the settlement effect of the actual process is monitored based on the numerical simulation results.Through the above analysis,the following conclusions are obtained :(1)The thicker silt layer under surcharge preloading can reach the desired target pressure by the method of drainage plate,but the loading cycle is relatively long,only relying on the static load is difficult to guarantee the construction period,can consider combining pre on silt layer the thick soft base processing pressure method.(2)With the loading process,the hydrostatic pore water pressure is rising continuously,the excess pore water pressure dissipates continuously during the constant load,and the ratio of the increment of the excess pore pressure and the increment of the load exceeds the design control value.Pore water pressure with the increase of load,rest,pore water pressure of growth and dissipation,into the preloading period obviously,the pore water pressure decreases;the pore water pressure gradually dissipated when continued drainage pumping construction reduces the pore water pressure on the spot;(3)Overload treatment can be carried out only when the preloading method of the drainage plate can not meet the design requirements of post construction settlement.The pre load is greater than the load,not only increases the period of preloading of soft soil consolidation degree of surcharge preloading,and reduce the coefficient of secondary consolidation of soil,the overload ratio increases,the coefficient of secondary consolidation is small and the occurrence of secondary consolidation of the delay time,the calculation of the minimum(about 1.3 1m~1.5m overload overload)can be used to meet the requirements.(4)When the surcharge preloading method is used,the consolidation time of the soft foundation can be greatly shortened compared with the non drainage plate.Through seepage simulation,it is found that adding drainage plate simplifies the path of water compression movement in soil layer,and reduces its moving distance greatly,thus improving the efficiency of soil consolidation under external load.The thicker silt layer under the condition of the dynamic and static load combination method is more effective to conduct dynamic load compaction of soft ground before loading,accelerate the consolidation process,can greatly shorten the construction cycle.