Taking the subway shield tunnel of Dagengjia Station to Longchuan Road Station of the first phase of Harbin Rail Transit Line 2 as the background, the freezing construction scheme and construction of the interval connecting-passage were introduced. The analysis and monitoring data show that the maximum settlement of the ground caused by the construction of the freezing method is -5mm, the maximum ridge is 6.12mm; the maximum settlement of the underground pipeline is -5.51mm; the maximum settlement of the connecting-passage is -7.13mm, the convergence value The maximum is 1.80mm, which is less than the construction control value and meets the construction requirements.

Metro tunnel sections in China can generally be divided into two types, those in granite formations (D = 6.0 m) and those in soft soils (D = 6.2 m), to which the same shield tunnel machine cannot be applied. The consequent low rate of machine utilization needs to be addressed. One solution is to modify shield machines which tend to tunnel granite strata with varying degrees of weathering (D = 6.0 m) into those applicable in soft soils (D = 6.2 m). Shield tunneling is a complex operation accompanied by potential risks, and accordingly it is demanded in risk evaluation and management. Hence, according to the construction features of modified shield machines in soft soil areas, this paper identifies relevant risks before establishing a specific model of risk evaluation by virtue of a fuzzy comprehensive evaluation method. This model weighs risk factors by triangular fuzzy numbers, and the membership function included is of L-R type that is frequently used in engineering. This risk evaluation model is applied to one section tunnel (Binhai New Town-Lianhua) of Metro Line 6 in Fuzhou City. Tunneling tests in the field uncover problems of the modified shield machine, including inappropriate tunneling parameters, segment dislocation, segment damage, and inadequate grouting. The result conforms to that produced by the risk evaluation model, which in turn proves the reliability of this model. Field data are also analyzed to address existing problems and to determine the appropriate tunneling parameters. The validity of these tunneling parameters is verified when surface settlement is measured.

Taking the large-diameter shield cutter head between Xinglong Station and Tianfu new station in Civil Engineering Section 4 of Chengdu metro line 18 as an example, the numerical simulation is carried out by finite element software to analyze the stress and deformation of large-diameter shield cutter head under different loads in upper soft and lower hard strata. The results show that the stress and deformation of cutter head meet the design requirements, which can provide certain reference value for similar projects in the future.

Taking Pile-Beam-Arc of Harbin Metro Line 2 Shengzhengfu station as an example, through the Midas GTS NX, different methods are used to establish the numerical model of PBA method. The results show that the quality of the model generated by the collaborative modelling method is better and the modelling efficiency is higher. The specific embodiment is that the number of units generated by the collaborative modelling method is less than that of auto-solid method, and the operation time of the model is reduced. The quality of the model generated by the collaborative modelling method is better than that of auto-solid method, which improves the model convergence and accuracy. The efficiency and application conditions of collaborative modelling method are better than those of plane element expansion method.

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