According to practical construction case of No.3 and No. 4 entrance / exit tunnel of Zongguan station in the 1^st phase of Wuhan Metro Line 3, this paper gives a comprehensive analysis of all kinds of possible emerging risks in the construction process combining the practical monitoring data. Considering that the pipe jacking construction technology has not been widely used in soft soil area like Wuhan, and the constructors lack experience of pipe jacking construction, it would be necessary to the all construction process if related personnel take some actions to prevent and control the existing risk problems in the construction technology. Meanwhile, it could also offer the valuable experiences to similar projects in the future. Through analyzing the process of pipe jacking and practical monitoring data in No. 4 entrance / exit tunnel of Zongguan station, we could draw the following conclusions : (1) Laying the monitoring points in different places of the construction site could effectively avoid the occurrence of risk; (2) During the construction process of No. 4 entrance / exit tunnel, the ground settlement is much larger than the surrounding buildings settlement, the maximum could reach 58.58 mm, and it would gradually increase with the advance of pipe jacking. (3) The settlement of the bridge pier around the tunnel constructed by Rectangular Pipe Jacking Method is very small. The settlement of the bridge pier is far less than 2mm, and the settlement value keeps stable in general.

Based on overlapping tunnel section from Hongshan Square Station to Zhongnan Road Station of Line No.2 and Line No.4 of Wuhan Metro, this paper proposed a principle of "finish the following part first" for subway construction considering the features of overlapping tunnels with short-distance. It mainly elaborated several key measures, such as shield tunneling control, grouting for mezzanine soil, temporary support in tunnels. Then the monitoring results proved the feasibility of the measures, so that this paper can provide reliable experience for the designation of overlapping tunnels and construction management in the following years.

Shield method construction. as a kind of safe and effective method of tunnel construction. plays a positive role in the construction of urban rail transit in our country. However, an interval, including partial hard rock section. iS difficult for shield tunneling machine to push forward. When the hard rock drivage reaches a certain length. we usually use "shield law" + "mines" composite construction method. Although this method can improve the construction speed and reduce the construction risk, but also causes many problems. According to the actual situation of Wuhan subway construction, this paper introduces the key technologies and quality control measures of shield to shield, shield advance and receiving phase with good results in the weathered mudstone formation of the hollow push mining method in tunnel construction, providing a useful reference for similar projects.

Because of its high mechanization, high automation and low-impact to the surrounding buildings and structures, shield tunneling has been widely used in the subway tunnel construction. However, deformation of stratum induced by shield tunneling is prone to cause inclination and even cracking or collapse of surrounding buildings. So there are so many safety risks in the subway tunnel construction that lead to frequent accidents. Based on the site measurement results, this article chooses a certain subway tunnel section of Line No. 2 of Wuhan Metro to systematically analyze and summarize the spatial and temporal effects and influence factors of the surface subsidence including the tunnel design parameters, geological conditions and the construction parameters. The research results are helpful to the shield operation parameter optimization and adjustments, controlling and reduction of the safety risks in the construction, and provide a useful reference for similar constructions in the future.