With the intensive development of China’s high-speed railway network and intercity railway network, the construction of the large-diameter shield tunnels and cross-passages is gradually increasing. The construction of large diameter shield tunnels and the excavation of cross-passages puts forward higher requirements for the stability and safety of segment structure. Based on the Wangjing tunnel project, this paper studies the segment displacement and mechanical response of the shield tunnel with a diameter of 10.5 m in the process of shield construction and cross-passage construction. The results show that during the construction of large diameter shield tunnels, the vault and invert produce inward displacement, the invert uplift usually is more severe than the vault settlement, and the arch waist on both sides produces outward displacement. Near the segment K (capping block), the mechanical performance of the segment is close to that of the hinge or chain rod, which can only effectively transmit the axial force but cannot resist the bending moment and shear force. During construction of the cross-passage, the maximum deformation and stress of shield tunnel segment are symmetrically located at the interface of the main tunnel and cross-passage. The upper and lower edges of the segment at the interface tend to change from compression to tension. At the same time, the steel bars on the inside and outside of the segment vault and the arch waist change from compressive stress to tensile stress, which can easily lead to segment damage, so these positions can be reinforced by erecting section steel frames before construction.

When the tunnel boring machine (TBM) construction method is used to build tunnels, if the type of TBM is not appropriate, problems, such as low construction efficiency and increased construction cost, will easily occur. Therefore, it is necessary to build a TBM selection decision-making model to guide TBM selection. In this paper, seven evaluation indexes are selected according to engineering experience and expert suggestions, and the quantitative standards of each index are unified. The modified analytic hierarchy process (MAHP) method is used to determine the weight of each evaluation index. The technique for order preference by similarity to an ideal solution (TOPSIS) method is adopted as the decision-making method of TBM selection. Finally, a TBM selection decision-making model is proposed based on the above methods. In order to verify the reliability of the TBM selection decision-making model proposed in this paper, we selected three projects for case verification and compared them with the previous TBM selection methods. The results show that the decision-making results of the method proposed in this paper are good. Additionally, the method proposed in this paper is more comprehensive and accurate than the previous methods. The model proposed in this paper can provide better suggestions for TBM selection in the project planning stage.

When a TBM carries out tunnelling in complex strata, there is often low tunnelling efficiency and an increase in tunnelling costs due to the improper selection of tunnelling parameters, the wrong estimation of geological conditions, or adverse geology, so it is necessary to evaluate the tunnelling adaptability of TBM construction. In this paper, based on hydraulic engineering in Xinjiang, 11 evaluation indexes of TBM tunnelling adaptability are determined by comprehensively considering the influence of tunnelling parameters, geological conditions, and adverse geological factors on TBM tunnelling adaptability. After that, the membership function of each evaluation index is determined by referring to the existing research results and fuzzy mathematics method, and the weight of each evaluation index is determined and adjusted by the analytic hierarchy process (AHP)–entropy weight (EW) method. Finally, the adaptability evaluation method and evaluation model of TBM tunnelling are put forward. The TBM tunnelling adaptability evaluation model proposed in this paper is verified by relying on the actual situation of three interval tunnels in the project, and good effects are obtained. This study can provide a reference for the evaluation of TBM tunnelling adaptability in similar strata.

Voids between primary support and secondary lining of existing tunnels pose a serious threat to safety and have become a key challenge for tunnel engineering. Due to the poor bonding performance between concrete slurry backfill and lining concrete, the integrity of supporting structures cannot be guaranteed. In recent years, vault grouting with formwork has proved to be effective in solving this problem. However, few studies have focused on the selection of grouting materials and associated grouting process parameters. In this paper, a slight-expanding concrete slurry is selected as the grouting material. The early strength growth trend of the slight-expanding slurry is explored via laboratory tests. The compatibility of the slight-expanding slurry and the lining concrete is analyzed by comparing the slump, expanding diameter, water retention and compressive strength. Bonding-body specimens were fabricated using a mold developed for this work. Furthermore, we compare the compressive strength and failure mode in order to investigate the bonding properties between the sight-expanding slurry and lining concrete at different grouting intervals and pressures. A reasonable set of operational parameters is subsequently proposed. Finally, field tests undertaken in an expressway tunnel in south China are performed in order to determine the impact of grouting with formwork on tunnel lining, while the grouting effect at the vault is evaluated using a ground penetrating radar. The slight-expanding slurry exhibited a high early strength and rapid hardening. Adding slight-expanding slurry to lining concrete at a volume ratio of 1:0.2 increased the slump, diameter and compressive strength by 13.4%, 15.6%, and 25.0%, respectively. When a grouting interval is less than 6 h, the pressure of grouting with formwork should be no less than 0.2 MPa, while for a grouting interval of 8 h, the grouting pressure should be no less than 0.4 MPa. The grouting pressure of 0.4 MPa exerts a limited effect on the existing secondary lining concrete, and the stress increment produced by grouting accounts for 6–17% of the total increment. The results presented can provide a reference for future tunnel construction.