Underground space disaster prevention is the basis of building a disaster prevention city. The disaster causing factors of urban underground space and assumption of disaster prevention system are proposed. Firstly, the characteristics of heavy rainstorm and disaster in Henan are analysed, the main disaster causing factors of urban underground space in rare heavy rainstorm are discussed from the aspects of hydrogeological conditions, landform, drainage and waterlogging prevention system. Then the strategies of urban underground space disaster prevention system during heavy rainstorm are proposed from the aspects of extreme weather disaster risk assessment, disaster prevention and control planning, post disaster urban recovery planning and so on. Finally, in view of the complex and diverse challenges faced by urban underground space, thoughts are expounded on the construction of urban underground space in the future from the aspects of ecological urban underground space planning, the construction of scientific underground space prevention system and the improvement of underground space disaster emergency rescue measures.

The characteristics of underground engineering balance theory were further analyzed from the three aspects of the load-support balance of tunnel surrounding rock, coordinated control of surrounding rock support and deformation, and rock conservation of energy in order to solve the problem of tunnel rockburst and large deformation of soft rock under high stress. According to surrounding rock grades, the theoretical characteristic curves of tunnel support structure resistance and surrounding rock deformation based on the equilibrium and stability theory of underground engineering were described; and the corresponding construction suggestions were also proposed. The suggested coordinated control method for the surrounding rock balance and support structure deformation was developed by evaluating the variation law of effective load and energy conversion characteristics of the surrounding rock and support structure. A new tunnel surrounding rock support device characterized as "energy absorption and pressure release, support and resist compression" was designed by combining with the high strain energy absorbing material. Finally, the application in engineering showed that the application of the new technology used in rockburst and soft rock large deformation tunnels reduced the surrounding rock pressure by about 28.09% and ensured the safe and efficient construction of the tunnel.

In the context of the China’s vigorous promotion of construction industrialization, prefabricated assembly construction technology has received extensive attention and development. Compared with a large number of research and application of above-ground buildings, the application and development of prefabricated assembly construction technology in underground space still has great potential. At first, the Citespace software is used to visually analyze the literature related to underground assembly from 2000 to 2022. Then, taking three typical underground space buildings of underground comprehensive pipe gallery, subway station and tunnel as examples, and the research and application status of prefabricated construction technology in underground engineering in China are summerized. Five key research contents of prefabricated construction of underground engineering are proposed, including the assembly technology of prefabricated lining, the mechanical performance of prefabricated structures, the connection joints of prefabricated components, the seismic performance of prefabricated structures, and the waterproof performance of prefabricated structures. Finally, five research trends of prefabricated structures in underground spaces are summarized to provide references for the popularization and application of prefabricated technology in underground engineering.

Understanding the seepage and failure characteristics of rough fractured rock masses under thermal-hydro-mechanical(THM) coupling is crucial for exploring temperature field distribution in hydrothermal high ground temperature tunnels during construction. This study investigates the failure modes and seepage-heat transfer characteristics of sandstone through laboratory THM triaxial loading tests and multi-physical field coupling numerical simulation, considering various initial rock temperatures (25 ℃, 50 ℃ and 75 ℃) and fracture roughness coefficients (JRC). The main findings are as follows: 1) Under THM coupling, the stress-strain curves and failure modes of intact and fractured sandstones are basically consistent. The stress-strain curves exhibit 5 distinct stages: initial compaction stage, elastic deformation stage, stable crack propagation stage, rapid crack propagation stage, and post-peak stress stage. The variation pattern of permeability strain curves correspond to those of stress-strain curves. 2) Prefabricated fractures reduce the sandstone’s peak strength by about 7%. The duration of the post-peak stage decreases with the increase of JRC value, shifting failure behavior from ductile to brittle. The fracture surface angle increases with JRC, and rougher fractures are more prone to shear failure originating from the extreme points of sine curve. 3) The permeability of the fractured specimen first decreases to its minimum value during the initial loading stage, and after 2 growth stages, the permeability reaches its maximum value. In the early stage, seepage primarily occurs through the rock matrix and prefabricated fractures, while in the later stage, the expansion of prefabricated and newly developed cracks significantly broadens seepage channels, with permeability growth rates approximately 3 times higher than that of the early stage. 4) Temperature elevation significantly affects the initial and minimum permeability values but has a limited effect on the strength characteristics of the sample.