| With a great deal of tall buildings and substructures constructed, the excavations are becoming more and more. The design and construction of the excavation are becoming more and more difficult. Now, The theories and the calculating methods of protecting design for excavation in the home and abroad chiefly include the limit equilibrium method, the subgrade reaction method and the finite element method. The limit equilibrium method cannot meet engineering design demands frequently as too much factors ignored, and the application is becoming littler and littler. The finite element method is mature in theory, but it is difficult to fix the earth model and the soil parameters, so being difficulty to be practice applied. The elastic subgrade reaction method is used more and more in recent years. But the study on it is not sufficient, so the method used now cannot consider the protecting structure-soil nonlinear interaction yet. Besides, the existing means to analyze the spatial effects of deep excavation are not practical, because too complicated or too simplified. For make the elastic subgrade reaction method to be consummated and explore the new practical means to analyze the spatial effects of deep excavation, the following main achievements are obtained by study in this dissertation.1. A new earth pressure computation model that able consider the protecting structure-soil nonlinear interaction was put forward, based on the P-y curve equation of horizontal loaded piles. The factors and mechanisms to influence the scale coefficient "m" of the elastic subgrade reaction method were studied thoroughly. Then suggesting that the retaining wall horizontal displacements and the difference between the active (or passive) earth pressure and the earth pressure at rest to be departed out from the influence factors of "m" in this dissertation, and consider merely the influence of the soil nature. In other words, to fix only the scale coefficient "m0" of initial horizontal foundation modulus, cause the model's parameter became simple. And then the method to fix "m0" was suggested by analysis the differences between the horizontal loaded piles and the protecting structures, which the "/wo" equal to one half of larger "m" in ((Technical Code for Building Pile Foundation)) according to the earth category and the retaining wall constructed situation. So the new model can be applied conveniently. It was verified by actual measure datum, and the results show that no matter the development tendency or values of the earth pressure calculated by the new model accord with the actualmeasure values well.2. Based on the new earth pressure computation model, the basic principles and calculating methods of the elastic subgrade reaction method considering the protecting structure-soil nonlinear interaction were advanced. The loaded and deformation features of the protecting structure that considering protecting structure-soil nonlinear interaction in different construction stages were studied. The differential equation and computation model of the beam were put forward based on the new earth pressure computation model. The calculating process of this method was gave by analysis the project instances. The solutions make known, the results accord with the actual measure values well over the excavating surface, and more close to the actual measure values under the excavating surface also.3. The spatial effect manifestations and laws of different kinds plane shape deep excavation were studied. The means to analyse the spatial effects of deep excavation were summed up, and their disadvantages were analyzed. Then the displacement back-analysis method to consider protecting structure-soil space nonlinear interaction of deep excavation was advanced. The radial basis neural network was led into the displacement back-analysis of deep excavation first, and unite the nonlinear interaction elastic subgrade reaction method, the principle and calculating methods of the displaceme...
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