中文摘要：

随着宁波城市建设的持续、快速发展，如何控制软土地区密集城区中深基坑工程的安全稳定和变形，避免由于基坑卸载变形过大导致周边环境和设施的沉陷、开裂、破坏，已经成为目前一个迫切而重要的课题。在对国内外现有关于基坑的变形规律、控制技术和控制标准的理论、实验和经验数据方面的文献资料和科研成果分析的基础上，结合宁波轨道交通建设工程实践，基于14个深基坑工程实测数据，对宁波地区软土深基坑的变形特性进行研究，探讨了基坑水平位移和地表沉降的基本规律，进而基于实测数据，并采用数据挖掘方法建立了基坑监测过程中的预警指标体系。尽管，宁波地区基坑工程实践水平较高，相应的设计理论、计算方法、技术研发及设备研制等方面则相对滞后。该文成果可以为宁波地区软土深基坑开挖变形控制提供参考标准，以达到控制基坑变形，保护周边环境和设施的目的，也可以为国内其他软土地区软土基坑的变形控制提供借鉴作用。

英文摘要：

With the continuous and high speed development of the urban construction in Ningbo city, the research on how to control the stability and deflection of deep excavations in an urban district of a soft clay region to avoid the settlement, cracking and destroy of neighboring facilities is quite necessary. Therefore, the available literatures about the theory, experiment and numerical modelling for deformation, control technique and control criterion of the deep foundation pit engineering are analyzed in this article firstly. Then, the Ningbo urban rail transit project construction is reconsidered, the deformation law for deep foundation pit engineering is investigated, and the characteristic of horizontal displacement and settlement of ground is obtained by the base of the monitoring data of 14 deep excavations. On the basis of deformation characteristic, the method of data mining is used to present the forewarning index for foundation pits monitoring, which can provides control criterion for deflection of deep excavations in the Ningbo soft clay region. Although, there is a great deal of practice on depth foundation pit engineering in Ningbo city, nevertheless, the theory of design, calculation method, research and development for technique and equipment are relative lagged. Thusly the results of this paper can present a basic criterion to protect the neighboring facilities in Ningbo area, and can present as an example for the other areas of soft clay.