大型沉井结构施工力学模型的研究

大型沉井结构是当今应用较广的基础工程，由于沉井结构的规模大，工区土层复杂，存在有许多不确定性因素。使得施工过程的力学模型比较难确定。迄今尚缺乏可供借鉴的理论研究。由于施工的关键是保证沉井的均匀下沉，控制终沉和防止突沉，为此，建立合适的施工力学模型以预测下沉量和开挖量之间的关系就十分必要，考虑到混凝土沉井在土体中下沉时，其本身的变形很小，可以忽略其影响，本文从多自由度刚体运动的角度，建立沉井下沉过程的动态力学模型。为验证所建模型的正确性，本文对一实际工程进行了数值仿真计算。并将计算结果与实测结果进行了对比。结果表明，所建立的力学模型能较好地反映沉井下沉的工程实际，因而可以应用该模型对沉井下沉进行预测分析。从而有助于指导沉井的实际施工。

Mechanics Model Study in Large Extra Caissons Construction

Large extra caissons are rather popular foundations nowadays. Since the properties of soil are non-elasticity and nonlinear, there are lots of uncertainties existing under construction. Up to now, it is hard to establish a suitable mechanics model, and seldom investigation can be provided useful theory reference. However, the most important fact which the builders concern with is uniform sink attitude in construction, control final sink depth and avoid sudden sink. For this reason, in order to predict the relation between the sink depth and the volume of excavation, the key point is to establish a suitable mechanics model in construction. Considering the deformation of the concrete extra caisson itself moving in soil is quite small and can be ignorant, a dynamic mechanics model in construction was derived from the standpoint of rigid motion of multiply-degree-of-freedom system. The relationship between the sink depth and excavation could be predicted by solving the mechanics model. To verify the proposed mechanics model, a practical engineering had been applied to compare the calculated results of the proposed model with measured results. The establish model can exhibit true sink behavior quite well, this help to predict the sink situation in construction.