复合地基沉降发展规律研究

With the development of China's civil engineering construction, composite foundation has been widely used in constructional engineering, municipal engineering, traffic engineering and railway engineering. However, our understanding in the settlement development law for composite foundation is insufficient, especially the calculation theory of post-construction settlement is still immature, which results in the big gap between the calculation results and the actual ones and affects the further development of the application of composite foundation. By means of field test, laboratory physical model test, theoretical analysis, numerical analysis and also back-analysis of engineering cases, this project intends to reveal the settlement development law of composite foundation with time, propose the calculation methods of settlements and post-construction settlements, develop the design approach for various composite foundation based on deformation control and eventually serve for constructions. The project accounts for the influence of the coupling effect of the consolidation of the soil between piles and the change of the pile-soil stress ratio, the superstructure rigidity and the properties of the underlying soil on the settlement development for composite foundation. The research on the settlement development for composite foundation is of significant value both in theory and engineering application.

随着我国土木工程建设的发展，复合地基在建筑工程、市政工程、交通工程和铁道工程中得到了广泛应用。但由于复合地基沉降发展规律，特别是复合地基的工后沉降计算理论还很不成熟，理论计算值和实测结果差距较大，这影响了复合地基应用的进一步发展。本课题通过室内外试验、理论分析和数值分析，并结合工程案例反分析，考虑桩间土体排水固结与桩土应力比发生改变之间的耦合作用、作用在复合地基上的上部结构的刚度和复合地基加固区下卧可压缩性土层特性等因素对复合地基沉降发展的影响，揭示复合地基沉降随时间的发展规律，提出各类复合地基沉降及工后沉降计算方法，发展变形控制的复合地基设计计算方法，为工程建设服务。开展复合地基沉降发展规律研究，既具有重要的理论意义，又具有较大的工程实用价值。

依照申请计划，课题组通过理论分析、数值模拟对复合地基在各种工况下沉降性状进行了分析，并将研究内容拓展到工程实践中。首先，对刚性基础下打穿及未打穿软土层粘结材料桩复合地基固结问题进行了求解，并对两种情况下地基的固结性状进行了分析。接下来采用有限元数值分析对路堤荷载作用下的粘结材料桩复合地基固结沉降发展规律进行了研究，并提出了改善地基沉降的建议。然后，基于散体材料桩固结理论，对散体材料桩复合地基桩土应力比发展规律进行了一定研究。最后，在现有理论及数值研究的基础上，课题组参与设计古顺变电站地基基础的设计，并提出了复合地基的长期观测方案。依托本项目，课题组已发表论文8篇，其中有3篇SCI，同时有5篇论文拟发表，已培养博士2名，1名博士在读。该项目的完成对进一步揭示复合地基的发展规律具有重要意义。