Study On Anti-Seepage Technology In Maluan Seawall Renovation Project

Maluan seawall of Xiamen was built in the end of 1950s, the purpose of the initial was to take Maluan Bay as a base for the salt industry and aquaculture . Because of decades of over-exploitation, and the sediment carried by surrounding streams flowing into the bay, the Maluan Bay and the western sea waterway of Xiamen are silted up seriously. The ecological environment and the water quality are becoming bad . According to Xiamen's urban development plan, Maluan Bay will be developed into a modern waterfront city. So this can take full advantage of the environmental conditions of Maluan Bay. The local government decided to open and renovate the Maluan seawall so that the water surface area will be expanded, the reservoir capacity and the tidal capacity can be increased. By this means, the exchange of the water in the bay will take place, the water quality of the bay will be improved and the comprehensive capacity of development in Maluan Bay area will be enhanced. One of the major engineering of the seawall renovation project is to build a 9-hole tidal gates with each hole in 24m width at the original location of the dock. According to the design , the outside cofferdam which about 530m long of the Maluan seawall is used in the construction of the tidal gates,and in the Bay a 633m long new cofferdam will be built. Then an foundation pit about 38500m2 has constructed to insure that the project proceeds smoothly.Combing with "Technology research of Xiamen Maluan seawall impervious curtain", this paper studies anti-seepage curtain technology and numerical calculation for Maluan seawall. First, earth-rock dam seepage of process technology and the application of anti-seepage curtain has been investigated. The research has contrasted three kinds of impervious wall: high pressure jet grouting in the sand layer, low-pressure grouting in the riprap layer and punching row piles cut-off wall.Through presses the water test, determining the construction quality and the effect of seawall impervious curtain, then calculates its penetration coefficient. Summarizing a economic and quality assurance construction program in view of the geological complex seawall.Using the finite difference method, the foundation pit seepage and seawall excavation fluid-solid coupling numerical analysis are carried out .This paper also analysis the influence of the highest tide level and the security of step-by-step excavation. Finally, by numerical analysis study the excavation works and municipal water pipes security which use different technical parameters of cut-off wall, reinforced soil permeability coefficient, anti-slide pile strength and depth.So it can provide the reference for the next related design.