ABSTRACT
With the increasingly stringent environmental protection requirements in China, the research on dredged soil treatment technology has become important. A new type of cofferdam with a mud-sand interbedded structure is described in this paper, including construction equipment, construction technology and design methods. The dredged soil is filled with a membrane bag and interbedded with a sandy membrane bag, which gradually forms a stable new cofferdam core structure. Through the finite element simulation results, it is known that after 55d of consolidation, the maximum displacement of mud-sand interbedded structure is 2.73 m, the top surface of the mudsand interbedded structure is 1.9 m from the back surface. The compression of the mud-sand bed structure occurs in the middle of the body, the bottom and top are less compressed. The design and construction of the cofferdam meets engineering requirements, and is a feasible, fast method to build a soft soil foundation for cofferdam's.
Offshore cofferdams are barriers against wind and wave erosion in coastal areas. In the past few decades, the types of cofferdam have emerged in an endless stream (Wang, C, 2008; Wang, H, 2014). However, most of them are made of rock, sand or a membrane bag soil. With the shortage of sand and rock and the continuous increase of costs, the construction cost of cofferdams increases greatly (Wei, 2017; Yang, 2009). On the other hand, dredged soil disposal, which is produced by dredging of waterway every year, brings great pressure to related enterprises. How to utilize resources without affecting the environment is the bottleneck of dredged soil management.
So far, in addition to the traditional sloped cofferdam type, new types of cofferdam structures such as a large-diameter vertical cylinder cofferdam, vertical caisson structure and semicircle cofferdam have appeared which are more suitable for deep water areas (Zhang, 2016). The sand cofferdam with a bag has been widely used in water conservancy projects. After entering the 21st century, the cofferdam with a mold bag with solidified soil core materials has appeared.
