| Foundation pit engineering is a systematic engineering that combines geotechnicalengineering and structural engineering as well as other subjects. It is highly comprehensive and canbe affected by many factors. Deep foundation excavation engineering contains not only theproblem of safety and stability of itself, but also may imperil the construction nearby, theunderground utilities, the city ground facilities and so on because of the moving of the layer aroundcaused by excavating the soil. Due to this, foundation pit deformation analysis becomes animportant sector during the design of the foundation pit.Soft soil is an extremely complex engineering material. Soil possesses not only the propertiesof elasticity and plasticity, but also the property of glutinousness, i.e. rheology characters. Theflowing deformation phenomenon of soil mass includes creep deformation, flow, laxity and so on.The creep deformation character is one of the most important engineering properties of the soft soiland it has significant impacts on the stability and safety of the construction. Due to this reason, thecreep deformation of the soil has been paid much attention to for a long time.Theoretically, traditional classical soil mechanics can not meet the requirements of thefoundation pit engineering, calculation theory and the relevant numerical computation methodsconsider the factors that can influence such as the creep property, the constitutive property of thesoil and the common effect by soil and building envelope, especially the finite element method hasbeen attached great importance by all circles that engaged in the foundation pit engineering.According to the complexity and deformation nonlinearity of the deep foundation pit, and onthe basis of on-site real time monitoring real-time deformation of supporting structure, throughusing the finite element numerical simulation and neural network inverse analysis and othermethods, we analyze and research on the selection of the soil parameter and displacement anddeformation of supporting structure of foundation pit.This paper carried out the work of the following aspects:(1) On the basis of ABAQUS finite element software, we take the creep deformation of thesoft soil into consideration and choose the viscoelasticity model and take advantage of the triaxialcreep deformation test to make sure the parameter of the model. We also adopt the planeframework model and make use of the equivalent supporting stiffness which transforms to planestrain pattern to imitate the excavation of the foundation pit. Finally, we calculate the horizontal displacement of the supporting structure that belongs to excavation of the foundation pit throughthe finite element.(2) Through adjusting to choose different numerical values of the specific parameter from thecalculation model, we calculate on the basis of the finite element and obtain the displacement valueat the different moment but the same depth, then we form a sample set for RBF network trainingand set up the mapping functional relation between parameter and displacement. Furthermore, wecalculate and obtain the corresponding calculation parameter values through taking advantage ofthe measured data which has been obtained during engineering measurement on the basis of theabove functional relation.(3) In order to consider the influence of space, we introduce the space revised coefficient.Through corresponding space shape that affects the foundation pit, we carry out the neural networkanalysis training to analyse the mapping relation between the corresponding parameter that affectsthe shape and the space revised coefficient so as to revise the parameter values from the test bymeans of the space revised coefficient. |
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