In order to study the advantages of frame support structure composed of rigid joint between steel strut and retaining pile in restraining the lateral displacement of retaining structure and maintaining the stability of foundation pit, foundation pit failure test was carried out. Compared with the traditional support structure, which can only bear pressure composed of steel strut and retaining pile lap joint, the variation characteristics of pile lateral displacement and support axial force of frame support structure under the influencing factors, such as weak stratum, pit side loading, groundwater level rise, and support drop, are studied. The test results show that, compared with the traditional steel strut, the pile-strut frame support structure can not only bear the compressive stress, but also the tensile stress caused by the lateral displacement of the top of the retaining pile outside the foundation pit. The overall stability is better, and the axial force distribution of each layer of support is more uniform so as to reduce the overall lateral displacement of the retaining pile. In the process of foundation pit collapse, the frame support structure will not have the problem of strut falling, which can maintain part of the support capacity, prolong the collapse time of retaining piles, strive for more escape time for front-line construction workers, and reduce the number of casualties.

Using RFPA software, the hydraulic pressure resistance and damage process of the grouted stone body of a tunnel in the high-pressure karst zone were analyzed, and the hydraulic pressure resistance of the composite surrounding rock and composite structure when the tunnel was expanded through the cavern under the effect of hydraulic coupling was investigated. Then, a new parallel heading expansion scheme for the New Yuanliang Mountain Tunnel was innovatively discussed, and the reliability of the results of the calculation model was verified by a field test. Lastly, the model calculation results guided the project to adopt a 5 m grouting range and advanced secondary lining to ensure that the composite structure’s water pressure resistance could reach 3 MPa; by adopting the improved technology of parallel heading expansion based on the CRD method, the safety of tunnel expansion through the cavity was effectively ensured, which can provide a reference for similar projects in the future.

Considering the convenience of pedestrian transfer, reasonable structural stress and beautiful shape design, most subway stations adopt symmetrical design. At present, the new subway station is developing in the direction of a multidimensional space, as well as a large scale, and complex structure. Tunnel construction also presents unpredictability, coupling amplification and high risks. For example, a subway extension project involves construction, which would affect the normal use of the subway or damage its structure. Based on excavation of the largest underground subway station under construction in China, the Erligou station extension project (line 16 of Beijing Metro), and using theoretical analysis, numerical simulation, monitoring data, and other research methods, this paper quantitatively analyzes the risk of a large space station’s construction process on the adjacent existing station structure and track, as well as highlights key, high-risk sub-projects, or construction steps, combined with specific engineering measures to ensure safety during construction of a new station. The general rules concerning large space subway station construction are further summarized to provide reference for similar projects.

The factors leading to the collapse of tunnel face are diverse, and there is an interaction relationship between multiple influencing factors at the physical and mechanical level. By analyzing the coupling relationship between the factors affecting the instability of tunnel working face, this paper deduces the calculation method of the coupling effect of tunnel construction risk factors for a certain risk event based on conditional probability theory, and makes reasonable assumptions on the monitoring data and risk probability. Finally, it is verified by a model test. The results show that the tunnel construction risk factors have a coupling effect by affecting other risk factors or changing the physical and mechanical parameters of surrounding rock, in which the coupling amplification effect will significantly change the failure probability of the risk carrier, so it is unfavorable to the stability of the tunnel face. The coupling amplification effect of risk factors will cause the increase of tunnel face extrusion deformation. Even if it causes a small deformation increment, it can also make the transition of risk probability and grade of tunnel face unstable, and cause tunnel face instability collapse. The research results of this paper can quantitatively evaluate and predict the stability of the working face in the process of tunnel construction.