Research On Foundation Treatment Method Of Binhai Avenue In Putian,Fujian

The modern coastal cities witness the highlighted economic benefits from port distribution,dramatically increasing land value,and the urban expansion to the borders of the sea.It's usual to use a coastal road as the most marginalized boundary of the city and the outermost land route.However,due to mostly the soft soil,treatment of soft foundation is essential for guaranteeing the long-term stability and safe use of roads,and for consistency between post-construction settlement and regulatory requirements.In particular,as the widening and reconstruction of existing seawalls and low-grade coastal highways make construction more difficult,special studies and treatment of splicing and settlement differences between old and new foundations are needed.Because of reservation for the river branch outlet to the sea,ship gates in the inner sea and other geographic factors,it's not unusual that coastal roads are often bridged.However,because of excessive settlement of soft foundations,“bumping” at bridge-head caused by the foundation subsidence has negative impact on driving comfort and traffic safety.Therefore,the research on the treatment of coastal soft foundation is very important for construction of high-grade coastal roads.In this paper,the typical soft soil in various coastal regions of China is combed and studied,and the common treatment methods for coastal foundation at home and abroad are summarized and referred to.In addition,an example of engineering design of Binhai Avenue in Putian City of Fujian Province is taken,and in-depth investigation of actual constraints ofthe project is conducted.Through targetedly comprehensive analysis,soft foundation treatment plans are compared to find out a multi-stage comprehensive soft foundation treatment plan suitable for the project,so as to reduce project cost as much as possible while guaranteeing the quality.For the stack-load preloading method for the new and old foundations which are spliced for widening,the preloading settlement and the road design elevation are combined to scientifically refine the preloading height according to different sections and different situations and control the elevation to a reasonable degree after preloading settlement.For the new and old road embankment joints,combination of digging steps and adding geogrids can prevent from differential settlement.As for the soil foundation treatment plans for “bumping at bridge-head” and other special sections,the static pressure prestressed concrete rigid pile composite foundation treatment method is adopted so as to reduce the impact on the original road foundation.At calculation and analysis,considering that the pile top cushion,prestressed concrete pipe pile body and upward and downward penetration of piles can be ignored,only the compression of the soil below the pile tips is calculated using the general method for calculating the substratum compression of reinforced field in composite foundation.Then,the difference between the actual situation and the simplified calculation model is analyzed,and the empirical parameters of the computing formula is standardized using post-settlement observation reverse.Because the flexible cushion in the upper part of the pile tip is considered to have a relatively large rigidity,and the Boussinesq solution takes into account the influence of the additional stress and the geometric parameters of the pile group when settlement of the pile foundation is calculated using the Mindlin displacement solution,it's deduced that the regional empirical coefficient can be set as a large value in this project,and the calculation results are in good agreement with the actual situation.This paper discussed strengthening effect of embankment by different treatment adopting numerical simulation,and the results of settlement pattern were compared with original non-treatment case.After obtaining preliminary results,further analysis were conducted that the stress distribution of foundation soil and variation of pore water pressure were analyzed considering the construction loading duration and road traffic loading effect.As a result,the understanding of strengthening effect with different treatment method can be improved.