APPLICABILITY ANALYSIS OF DOUBLE STEEL SHEET PILE UNDER SPECIAL GEOLOGICAL CONDITIONS IN COASTAL ZONE

The double-row steel sheet pile structure(DSSPS) is a soil-retaining and water-stopping composite structure. It composes of two rows of steel sheet piles, soil between the piles and tie rods. Compared with earth-rock dikes, it has a smaller footprint, faster construction speed, better integrity than steel sheet piles, and good dynamic stability against earthquakes and waves. It is widely used in water conservancy, water transportation, and coastal engineering. However, because DSSPS is greatly affected by geological conditions, its application effects and costs are not the same. This article focuses on collecting and investigating the use of double-row steel sheet piles in coastal projects at home and abroad. The effects of double-row steel sheet piles on karst-developed lithological foundations, high-permeability sand foundations and deep silt soft soil foundations have been investigated. Performance impact and design constraints are analyzed. Combined with the original geological conditions and design data, the finite element software is used to supplement the calculation and analysis. The application effects of the double-row steel sheet piles under various types of engineering geological and hydrological conditions are analyzed. The different projects of the double-row steel sheet piles in the coastal zone are summarized. It is found that the construction of double-row steel sheet piles in karst developed stratum needs to prevent leakage problems caused by poor verticality and karst connectivity caused by pile driving. In the sandy soil layer, it is necessary to prevent the inclination and deformation of the steel sheet piles from deteriorating the water-stop performance of the lock, which in turn leads to water leakage and even quicksand. During the construction of silt formations, the construction of the driven pile and the water-stopping performance of the pile body can be guaranteed, but a large overall deformation of the pile body may occur. At the same time, the inner pit bottom reinforcement should be considered to avoid the stability of the kicking foot. The findings of this article has engineering guidance value for the development of coastal ecological engineering geology and coastal resilient hydraulic structures.