Study On The Optimum Sectional Form Of Geocell Retaining Wall And Application In Yan’an Airport Relocation Project

As a new type of slope protecting structure, the geocell flexible retaining wall has a brilliant application prospect in highway, railway and other fields due to its advantages of light structure, less requirement for foundation bearing capacity, convenient construction, less cost and can meet demands of greening environment and ecological protection.At present, unified and traditional cross-section of geocell retaining wall(GRW) are adopted by plenty of engineering practices. Such sectional forms not only needs numerous materials, can’t fully reflect the tensile strength of geocell, but also higher retaining wall prones to “bulging” obviously. Therefore, in order to decrease the horizontal deformation, enlarge the safety factor and reduce the amount of materials of the wall effectively, it is urgently required to optimize the current sectional forms and promote a new type of that.In this paper, by employing the geotechnical FEM software, the optimum sectional form of the GRW is investigated. With the design, the construction and local monitoring of the varied-sectional flexible retaining wall which applied in Yan’an airport relocation project, a preliminary analysis of the mechanical behaviors of the new sectional form GRW are studied by 3D numerical simulation, some progresses as followed 4 aspects.1. The effects of the location and the length of the lengthening geocell layers, the position and the strength of high-strength geocells and the surcharge on the surface of the slope top on the horizontal deformation and the safety factor of the GRW are researched by numerical simulation method.2. Based on the theoretical research, a new type of sectional form of the GRW which not only increase the safety factor, but decrease the number of materials is proposed and applied in the engineering practice of Yan’an airport relocation.3. The processes and precautions of the construction of the varied-sectional GRW are summarized. The horizontal displacement, the earth pressure and the settlement of the retaining wall are reflected by field test. The horizontal deformation is “the middle is big, the two ends is small", the settlement quickly stabilized and the earth pressure of the wall back essentially is the rule of "the upper is small, the middle and lower is near-linear growth".4. The FEM membrane element and the embedded element technique are applied to simulate geocell and filler separately, which not only the stress and strain of the geocell of the retaining structure can be investigated respectively; but the confinement effect of the geocell to the filler can be displayed truly. A 3D numerical simulation method is proposed and the effectiveness of the method is illustrated with the results of local monitoring. Then, the mechanical properties of different sectional forms of retaining walls are analyzed with such method, which provides a theoretical basis for the promotion and application of the varied-sectional GRW.