Steel sheet pile used as foundation anti-seepage treatment of embankment project is a new technology used in the hidden embankment construction of important dyke in the Yangtze River. Until 1998, there was no precedent for application in this area. Seepage prevention project of steel sheet pile, steel sheet pile foundation is into the permeable layer under relatively impermeable layer, seepage interception aquifer, the formation of a semi closed or closed diaphragm walls, which plays the role of foundation seepage. Foundation anti-seepage reinforcement by steel sheet pile has advantages of processing depth, good anti-seepage effect, the construction of small impact to the adjacent buildings and the construction speed is higher, but the total cost of the project. Steel sheet pile construction technology requires high, only strictly control the axial and normal tilt deviation, in order to make the steel sheet pile into the smooth, to ensure the closure of the cut-off wall.
With the vigorous development of water conservancy and hydropower projects, large scale foundation pits are used in many hydraulic projects in china. Steel support is one of the important supporting wall protection technology, and there are many kinds of support forms and materials in the foundation pit. Reasonable support type should be adopted according to the specific conditions of the project. For example, in the process of pipeline foundation pit construction, the types of support mainly include slope excavation, cement mixing pile support, shotcrete and anchor support, etc.. However, in many of the outdoor construction site, because the constraints and limitations of various technical and environmental conditions, many support types of complex environmental conditions can be achieved, then need a can meet the conditions, but also can satisfy the construction conditions, and economic benefit and good supporting type and steel pile support just to meet this demand. The engineering practice shows that the steel sheet pile can be used to support the water conservancy project construction, not only can achieve the purpose of water sealing, but also can achieve the purpose of supporting, and has enough strength, so it can get good economic benefits.
Steel sheet pile support is a kind of support method with simple construction and investment economy. It consists of pile sheet, anchor rod (or internal support anchor structure, waist beam, etc.). Due to the flexibility of steel sheet pile sections itself, such as supporting or anchor system is improperly set, its deformation will be great. But if the foundation pit depth is too high (such as more than 7m), the foundation pit should not use steel sheet pile support, unless the multi layer support or anchor rod. In essence, steel sheet pile is a sheet pile structure in cantilever retaining structure, which has the advantages of light weight, high strength, close locking, convenient construction and fast construction speed. Although the steel is large, the steel sheet pile can be reused, so the cost is relatively low, the excavation depth is not large (soft soil area is less than 4m), and the underground water level is not high in the deep foundation pit support, the steel plate pile is more common.
Steel sheet piles are mainly made in China and imported in two major categories. Domestic main Larson steel sheet pile type saddle bag IV and type IV (U) two types. The domestic steel sheet pile is very harsh, and it is widely used in the deep foundation pit support. Imported steel sheet pile has two advantages in quality and cost, so it is used more in the actual water conservancy project construction. Japan and the United States are the countries which produce more steel sheet piles. Japan has Larson type Z, straight belly plate, H type, combination type and so on. The United States mainly has Z type, Larsen type, straight abdomen type and so on. In addition, some non-standard steel sheet piles are produced to meet the needs of different projects. Before the engineering calculation,How to classify sheet piling retaining wall according to the geology, hydrology and other conditions, according to the relevant engineering manual and engineering experience, the preliminary selection of steel sheet pile type is carried out.
