Design And Numerical Simulation Of Retaining And Protection For Excavation

With the rapid development of our nation’s social economy, the number of the middle-height and high structures has increased very fast. At the same time, the depth of some foundation pits has become longer and the acreage of that has become larger. In order to insure the safety of excavation of foundation pits and environment around, most of them must be braced instead of direct excavation because of the limited working space. As a new bracing method of foundation pits, compared with other retaining methods, the shotcrete-bolting technique has the advantages such as more economical, reliable, convenient in construction, less deformation, so it has used commonly in the field of engineering. However, as a new bracing method, the research of its action mechanism has not enough. At present, we still lack of a good calculating model which can simulate accurately its bracing rule, mechanics performance and the rule of deformation. In order to broaden its forecast theory and provide scientific basis for its broad application, the paper is based on its excellent performance in economic, technical, security aspect, and the three-dimensional Fast Lagrangian Analysis of Continua is used to analysis numerically the bracing structure of the shotcrete-bolting technique.The project of foundation pits bracing is summarized at first, together with the introduction of the parts that compose the shotcrete-bolting technique, construction process and the characteristic. Then the paper intruoduces the basic rationale of the three-dimensional Fast Lagrangian Analysis of Continua and the function of FLAC3D software. On the basis of the research in deformation rationale and the choice for constitutive relation which is used commonly, the paper uses Mohr-Coulomb Bow yield criterion as the constitutive model, and ensure the boundary condition, the gridding plot method and the excavation and Shotcret-bolting process. In the last part, linking with the real project example, the paper establishes the three-dimensional model. According to the compare and analyze between the result of stimulant transmogrification and that of real survey result in build site, the paper gets the sum-up of research conclusion and rule in lateral displacement, the perpendicular displacement and the stress of the bolt and the construction process of the Shotcret-bolting, and validates the rationality and advantage of the applying the three-dimensional Fast Lagrangian Analysis of Continua in the research of foundation pits Shotcret-bolting structure transmogrification.