Study On Subgrade Reaction And Settlement Of Raft Foundation Under Multi-ribbed Composite Wall Structure Based On In-situ Test

Multi-ribbed composite wall structure is a new structural system, which makes full use of fly ash and other industrial slag muck to replace clay brick; it has characteristics such as fast construction, good energy saving effect, green environmental protection, significant economic benefits and so on. The structure has application prospects. As a new structural system, when considering the structure-foundation-soil interaction, the measurement and analysis of subgrade reaction is particularly importanat. Based on the measured subgrade reaction of raft foundation under multi-ribbed composite wall structure, this paper take theoretical analysis and numerical simulation, and study on influencing factors of subgrade reaction of raft foundation under multi-ribbed composite wall, which provide the basis for engineering design. The main work and conclusions are as follows:(1) Based on "Zhongzhou Royal Palace" project of a multi-ribbed composite wall structure with eight floors in Lankao Henan, subgrade reaction is tested in-situ. Influencing factors of subgrade reaction of raft foundation under multi-ribbed composite wall are studied. The results show distribution law of raft foundation under multi-ribbed composite wall involved in structure of soil composition, horizontal and vertical stiffness and structure-foundation-soil interaction, measured curve of subgrade reaction in the vertical axis shows large in the middle and small on the edge, and measured curve of sub-grade reaction in the vertical axis shows small in the middle and large on the edge.(2) Combined with pre-test research group, the upper multi-ribbed composite wall structure is simplified as frame-composite materials equivalent elastic plate model, parameters of each elastic plate are calculated. From a macro point of view, using the composite analysis, the pile-soil system is regarded as composite material, the theoretical formula of subgrade reaction coefficient of cement soil mixing pile composite foundation is putting forward, and then calculated the key parameters of the Winkler-foundation model.(3) Multi-ribbed composite wall structure-raft-foundation interactive model is built up by using finite element analysis software SAP2000. When altering the stiffness of superstructure, raft foundation and soil, influencing factors of subgrade reaction of raft foundation under multi-ribbed composite wall are studied.(4) When the stiffness of the super-structure, foundation stiffness are changed at the same time, the relationship between the thickness of raft and foundation is researched. The results show when different parameters are changed, the foundation settlements are differrent, but the laws of settlement are very similar, and the more obvious factor that influences foundation deformation is raft thickness, which provides a reference for design of raft foundation under multi-ribbed composite wall structure.