Urban subway tunnels predominantly comprise shallow structures that traverse bustling city districts. The use of shield tunnelling methods during construction can effectively minimize the impact on ground surfaces. However, in the face of challenging geological conditions, such as hard rock, boulders, anchor cables, and varied layers of hardness and softness, shield tunnelling technology in China has not fully matured. As a result, employing shield tunnelling in these circumstances may expedite tool wear, diminish excavation speed, and necessitate more frequent tool replacements. This could lead to increased engineering costs and elevated safety risks. Considering these problems, it is prudent to consider a combined construction approach that integrates mining and shield tunnelling methods. Through the study of the combined construction method, optimization of the construction structure and engineering cost can be realized, and the safety hazards can be reduced, which is helpful in the successful completion of a tunnel project.
As the complexity of urban subway construction increases, new technical development demands have been raised for shield tunnelling construction. Research on the construction technology of shield tunnelling empty-pushing using the mining method has also made significant progress in China. In terms of construction technology research, as urban subway construction becomes increasingly challenging, new technological development requirements have been proposed for the shield construction process. In China, shield tunnelling empty-pushing construction using the mining method has made significant progress. Regarding construction technology research, Duan et al. [
1] determined the parameters of the Holmquist–Johnson–Cook model of the diorite in the Jinan area to ensure the accuracy of the rock-breaking simulation, using ANSYS to simulate the rock-breaking process to analyse the influence on the rock-breaking behaviour of the geometric configuration, including the blade width and blade fillet. Erharter et al. [
2] studied the friction coefficient for tunnel-boring machine excavation planning by shearing rock specimens with different lithology to optimise the construction parameters of the shield in terms of friction. Choi et al. [
3] experimentally evaluated the waterproofing performance of five sealant installation methods based on the type and number of layers of sealant, using a waterproofing performance test to determine the relative waterproofing performance of the tunnel tube sheets. Zhang et al. [
4] investigated the mechanical properties of the new structural material FWP through compression and bending tests, determined the key design parameters of the bearing capacity and stiffness through numerical tests, and proposed a calculation method that can be used to calculate the bearing capacity and stiffness of FWP in practical engineering. Meanwhile, Suk min Kong et al. [
5] compared the vibration measurement values generated when excavating the top surface using the existing NATM construction method and the TBM and NATM parallel construction methods, based on the vibration measurement data of the excavation site and using the NATM construction method; the vibration reduction effect of the two construction methods was analysed through 3D numerical analysis. Le et al. [
6] proposed an equation describing the relationship between volume loss and the liquefaction potential index by monitoring field data obtained during the construction of the Binh Thanh-Su Tien tunnel on line 1 of the Ho Chi Minh City metro in Vietnam, which was used in practice as an indicator of potential large settlements caused by EBP tunnel boring machines in sandy soils. Jie et al. [
7] examined the performance of blades made from 42CrMo low-alloy steel after different heat treatments, contributing valuable insights to fault prevention and cost reduction in shield machines. Numerous researchers domestically and internationally [
8,
9,
10] have pioneered key construction technologies by modifying shield machine construction methods and overcoming the technical difficulties of shield machine construction under diverse geological conditions. Regarding numerical simulation and analysis, Imteyaz et al. [
11] used the FEM-based software ABAQUS to analyse the deformation of specific rock mass characteristics under static and seismic conditions with and without lining. Islam et al. [
12] used MIDAS GTS NX to carry out 3D finite element numerical simulations to optimize the geometric parameters and construction sequence of twin tunnels to help designers control the settlement caused during the excavation of back-loaded twin tunnels. Fang et al. [
13] suggested a modelling method based on the coupled finite difference and discrete element methods, simulating the interaction between the shield machine and the layered rock mass. They further discussed the progressive failure mechanism of a layered rock mass. Moghtader et al. [
14] developed an artificial neural network model that considered the non-linear relationship between the maximum surface settlement and 150 influential independent variables and collected real data from the Tehran Metro Line 16 project to build a training and test set to optimize the ANN technique, which eventually predicted the surface settlement of the above project accurately. Hussaine et al. [
15] used the open-source AutoML framework to construct different machine-learning models to predict the maximum ground settlement when shield tunnels are constructed on soft subsoil, with advantages in terms of prediction accuracy. Xiao et al. [
16] adopted four machine learning (ML) algorithms and four deep learning (DL) algorithms in shield machine attitude (SMA) prediction models, and finally integrated ML algorithms and DL algorithms to design a warning predictor for SMA according to the eight simulation results. Chen et al. [
17] formulated a hybrid prediction dataset that incorporated geological and tectonic parameters. They based this on sampling methods using spatial and time series to obtain an approximate range of subsidence to reduce the potential damage the project might inflict on the surrounding environment. Wang et al. applied the Matlab program of the BP neural network based on a genetic algorithm combined with engineering examples to achieve relatively efficient construction feedback through a forward analysis of construction parameters, which can effectively improve the response efficiency of unexpected conditions in the construction process. Many scholars [
18,
19,
20,
21,
22,
23,
24] have used finite element numerical simulation, machine learning method comparison, and genetic algorithms to perform the numerical modelling of shield tunnelling under special external loads, investigating the deformation characteristics and mechanisms of tunnel structures. The results of the digital modelling are used to predict changes in construction conditions, optimize construction parameters, and control construction quality.
In summary, domestic research on shield machine empty-pushing through mining method in tunnel construction has primarily focused on aspects such as construction technology, quality control, and monitoring and measurement techniques. However, research contributions in structural stress and design are somewhat limited. In practical scenarios, as tunnelling projects progress, frequent stress disturbances occur within the structure. This results in substantial changes in the internal forces of the tunnel structure, which often fluctuate under varying building conditions. During the construction of a mine method tunnel project, the internal force fluctuations can exceed their limits, leading to potential failure or even collapse, of the existing structure. This poses risks to buildings surrounding metro lines and complicates tunnel construction. Ensuring safety through excessive building measures would inflate the project’s cost. By studying the alternations in stresses within the tunnel structure in the current project situation, we can clarify the range and trend in potential stresses during construction. This facilitates the optimisation of the design criteria for the initial support and detailed structures such as tube sheeting, thereby achieving a balance between economic efficiency and safety. MIDAS-GTS software has a rich interface for importing solid files in various formats for creating realistic terrain and stratigraphic sub-interfaces by using a terrain data generator combined with borehole data, facilitating researchers’ studies. At the same time, MIDAS-GTS can output combined envelope results such as vectors, section output clouds, and tables for analysis. Thus, in comparison to the methods used by Le et al. [
6], Chen et al. [
17], and other scholars, MIDAS-GTS have a better advantage in 3D modelling. Therefore, this study focuses on a section of Changsha Metro Line 3 in China. We use MIDAS-GTS finite element software to establish a model of tunnel construction using a shield machine with empty-pushing through mining method, and carried out a relevant mechanical analysis. Several numerical models were created following actual construction steps to examine the effects of different construction conditions on the displacements in the x, y, and z directions and the internal stress distribution within the shield-driven section. In comparison with other tunnelling projects in China, the simulation results of this study can offer recommendations for construction standards for shield machine empty-pushing through mining method in tunnel construction on the basis of construction safety. According to the simulation analysis results, we offer recommendations for construction standards for shield machine empty-pushing through mining method in tunnel construction. The research findings can maximise the load bearing capacity of the structure and ensure the economic efficiency of the project costs, which can provide some practical engineering data to support similar tunnelling projects in the future.