In order to clarify the key points of machine learning in surface deformation prediction of shield tunneling, the development background of machine learning was introduced, and the engineering application of machine learning was summarized from the aspects of database establishment, data preprocessing, model framework construction and model evaluation. It was pointed out that the shortcomings of the current relevant research were the lack of professional public database and the uneven quality of engineering data; for engineering with different stratum types, the model was prone to over fitting. At the same time, the further development direction of machine learning in shield tunneling surface deformation prediction was discussed, including the effective combination of algorithms could learn from each other; there was still a large research and application space for feature selection and super parameter optimization.

This paper made a comprehensive literature review on the topic of applying machine learning methods to shield tunnelling parameter predictions, stratum predictions ahead of a tunnel face, surface settlements prediction, shield attitude deviation and tool wear predictions. The selections of machine learning methods and the associated input and output parameters were analyzed, and the shortcomings and challenges of existing research were summarized. Some prospects were given, including the model generalization, multi-source heterogeneous data compression and assimilation, data-physics-based intelligent shield tunnelling, big data in shield tunnelling, in order to provide reference and guidance for the future research and engineering practice.

This work systematically summarized four types of methods for predicting tunnelling induced ground movements, namely analytical solution, empirical equation, numerical simulation and model test method. The theory of four types of analytical solutions was firstly presented. The widely-used empirical equations and determination methods for the key parameters were introduced. The development of numerical analysis methods with respect to soil constitutive model and simulation technique was discussed. The 1g model test and centrifuge model test were presented in brief as well. Some suggestions on predicting tunnelling induced ground movements in China were presented according to the advantages and disadvantages of various methods.

The background of the invention of the double-mode shield machine/TBM was reviewed, the multi-mode shield machine/TBM was defined and classified. The working principle of the double-mode shield machine/TBM was explained. The applicable geology formation and environment of the double-mode shield machine/TBM was clarified. The effects of application of the double-mode shield machine/TBM were summarized. The paper has an important reference for the construction of tunnel boring machines under similar strata and environmental conditions.

According to the characteristics of shield tunnel construction and considering the hydraulic changes, a physical model test device for failure of shield tunnel face in sandy soil was designed. The displacement controlled loading of the excavation face was realized by pulling the rigid support face, and the earth pressure in front of the excavation face was measured. The high-precision digital image captured during the test was processed to track the instability process of the excavation face. 11 groups of physical model tests were carried out to investigate the failure mechanism of excavation face in isotropic and anisotropic strata and under groundwater seepage condition, and the ultimate support pressure to maintain the stability of excavation face was obtained. The results showed that with the increase of the deformation of the excavation face, the support pressure first decreased rapidly and then tended to be stable. The failure mode of the excavation face was composed of a sliding wedge and an upper prism. In anisotropic strata, the deposition direction of soil particle leaded to the variation of limit support pressure, and the height and width of loosen area in front of the excavation face changed slightly. Under seepage condition, the seepage of groundwater leaded to an obvious increase of the ultimate support pressure, the angle between the sliding surface and the horizontal in the failure state of the excavation face was small and the failure are abecomes large.

Based on the critical leakage width, a model test system of adjacent pipelines deformation induced by the joint leakage of shield tunnel was established, including the shield tunnel and pipeline model, simulation device of shield tunnel joint leakage, water level control system, and data acquisition system, the influences of the position, distribution and depth of the leakage on the deformation and settlement of the pipeline, the internal force of the pipeline and the pore water pressure of the soil around the leakage were studied. The results showed that with the increasing of the depth of the overburden soil, the vertical distance between the leak and the pipeline increased, and the water-rich sand layer would produce more soil and water pressure on the upper part of the support, and the settlement deformation and internal force of the pipeline would decrease under the condition of the same depth of overburden soil, the peak value of settlement and internal force of the pipeline decreased gradually as the position of the leakage seam deviated to the bottom of the arch, the corresponding position gradually moved away from the central axis of the tunnel, and the settlement deformation of the pipeline above the leakage seam side was obvious, the settlement deformation and internal force increase with the increased of the number of the single side leakage, the location of the new leakage was close to the arch crown under the condition of bilateral asymmetric leakage, the settlement deformation and internal force of the pipeline were obviously asymmetric with respect to the central axis of the tunnel. The monitoring value of pore water pressure could reasonably explain the distribution of seepage field around the leakage of shield tunnel. The closer to the leakage location was, the smaller the monitoring value of pore water pressure and the larger the dissipation value of pore water pressure was, water always flowed from a high to a low pore pressure position.

To study the stability of the ground during the opening of the rectangular jacking pipe, this paper presented a project of box tunnel in Suzhou, in which a particular case of obstruction clearance was involved. The distribution of the cuttings in the chamber was analyzed and the analytical model for ground stability was established accordingly. Considering the working face was partially supported, the current model was proposed by modifying the traditional silo-wedge model. The residual earth pressure supporting the working face was derived through limit equilibrium analysis. The comparison between the proposed model and traditional model was carried out for verification. The result indicated that the proposed model outperformed the traditional model on ground stability assessing when the width of unsupported area is one-half of the working surface(<i>B/L</i>&lt;1/2).

In order to establish a fast, accurate and efficient evaluation method for the impact of shield construction on adjacent buildings, the principal strain based on angular distortion and lateral strain was selected as the evaluation index to assess the damage to the building. Numerical investigation was carried out to explore the interaction between the building and the ground, and the results showed that the bending stiffness and the axial stiffness had a significant influence on the angular deformation index of the building, while the horizontal strain index of the building was mainly affected by the axial stiffness. A calculation method of building deformation index considering the influence of the building was established, and DPI as a measure of the influence degree was introduced. A method for evaluating the influence of shield construction on adjacent buildings was presented, which considered the interaction between buildings and strata, and was convenient for engineering application. The results of the proposed evaluation method were in good agreement with the field observed data.

Based on the engineering background of 4# connecting passage of Nantong Urban Rail Transit Line 1, the multi-field coupling variation law of freezing construction process was studied through monitoring data. A new multi-physical field data monitoring equipment was developed, and its basic characteristics and installation location were introduced. Finally, the monitoring data were analyzed and compared with the simulation results. The results showed that considering the dual influences of salinity and water flow in the saturated silty sand layer, the salinity slowed down the temperature of the soil in the early freezing stage, and the water flow caused the cooling capacity of the upstream Shennan Road Station to flow into the downstream Yongxing Avenue Station, which in turn delayed the actual freezing construction time by 10 days than expected. The above monitoring work ensures the safety of the construction of the connection aisle freezing method and provides reference data for other similar projects.