【作者】 吴华；

【导师】 郑刚；

【作者基本信息】 天津大学 ， 结构工程， 2007， 硕士

【摘要】 天津市区的城市建设正处于高速发展阶段,出现了一大批有影响的深基坑工程。另外,随着基坑规模和深度不断加大,由此产生的城市环境岩土问题成为工程建设中的重点难点问题。尤其是基坑开挖引起的土体位移对临近建筑物的影响越来越得到工程界的重视。如何从空间效应的角度出发,减少基坑开挖对周围建筑物的影响,本文介绍了空间效应在天津市区某工程基坑开挖过程中的应用,观测围护结构的变形和坑外建筑物的沉降,并用有限元分析空间效应对基坑开挖的影响,结果表明基坑开挖具有明显的空间效应作用,合理利用这种空间效应,将有效的减少围护结构的变形,同时减少开挖对周围环境的影响。土的力学性状与土体中应力变化过程、应力状态有关,常规的三轴试验并不能真实地反映土体经历的应力路径对其力学性状的影响。本文根据有限元计算结果得出的应力路径,通过对天津市区地层中第一海相层的粉质粘土原状饱和试样进行的一系列K0固结不排水应力路径三轴试验,研究考虑空间效应的基坑开挖过程中土体应力路径对其变形特性和强度特性的影响。试验表明,考虑这种特殊应力路径的土体的力学性状明显异于常规试验结果。在工程实践中应根据实际的受力情况、应力状态来确定相应的应力路径,以正确、合理地测定土的力学参数。更多还原

【Abstract】 Urban constructions of Tianjin are developing greatly. A great deal of deep excavation engineering has been coming forth. In addition, the geo-environmental problems become more and more important in design and construction of substructures with the scale and depth of excavation increasing. Especially, the environment response due to adjacent excavation-induced soil movements gets more and more attentions from the engineer. How to reduce the environment effect of excavation, Spatial effect is applied to foundation excavation in Tianjin, deformation of the support structure and the building settlement near the foundation pit are observed, and Finite Element Analysis is used to simulate the spatial effect on foundation excavation, the results show obvious spatial effect during excavation, Spatial effect using reasonably can reduce deformation of the support structure and effect on environments around the foundation.Mechanical properties of clay are related to stress variation and stress state. By using the conventional triaxial shear test, the effect of stress paths on it can not be reflected actually. With the self-made triaxial equipment, a series of Ko consolidation and undrained shear tests has been carried out to study the effect of stress paths in excavation of considering spatial effect on the deformation and shear strength properties of a typical soil in Tianjin city. According to the experimental results, the deformation and shear strength properties are different from that of conventional triaxial test. This shows that, in an actual project, the stress paths should be determined according to load case and stress state so that the mechanical parameters of clay can be measured correctly and reasonably.更多还原