With the implementation of the national western development and the "Belt and Road" strategic decision, transportation infrastructure construction in the western region has developed unprecedentedly. More and more traffic tunnels are being built through loess strata, and it is not uncommon to find loess tunnels undercrossing existing roads, coal mine goafs, and ground buildings. Loess, as a continental sedimentary deposit of the Quaternary system, has large pores, high compressibility, low shear strength, and is prone to collapse and disintegration when wetted. These characteristics make loess tunnels susceptible to collapses, roof falls, and significant deformations during construction. This project relies on engineering projects such as the Xizhou Tunnel and Duncun Tunnel of the Daxi Railway, and the Aobao Gou Tunnel of the Baozhun Railway. It focuses on solving technical challenges in constructing large-section loess tunnels that are shallowly buried into the ground and undercrossing highways, coal mine goafs, buildings, etc. The project team has achieved multiple breakthrough results after more than a decade of scientific research and engineering practice, forming key construction techniques and risk control technologies for shallow-buried and under-crossing loess tunnels under complex conditions. The main innovative achievements are as follows: 1. The team pioneered the construction technology for shallow-buried entry of large-section loess tunnels with long pipe sheds. It revealed the engineering characteristics of the soil body in shallow-buried large-section loess tunnels and the stress deformation laws of the surrounding rock and lining, proposed a reasonable optimization method for small sections with ultra-short steps in shallow-buried large-section loess tunnels and construction parameters, pioneered the 120m long pipe shed advance support technology for shallow-buried sections of loess tunnels and the glass fiber anchor pipe reinforcement technology for the working face, invented a construction method for the shallow-buried entry section of large-section loess tunnels, and achieved safe construction for shallow-buried entry of large-section loess tunnels. 2. The team created the construction technology for loess tunnels under-crossing highways. This paper reveals the stress and deformation characteristics of loess tunnels underpassing highways, as well as the variation law of arch effect. It establishes a calculation method for the surrounding rock pressure of loess tunnels, proposes a reasonable optimization scheme for less-divided ultra-short benching method and construction parameters for tunneling underpasses, develops a high shear strength shotcrete, creates a construction method for loess tunnels underpassing highways, forms a complete set of construction technologies for loess tunnels underpassing highways, and achieves safe construction of such tunnels. 3. A construction technology for loess tunnels passing through mined-out areas is created. The stress and deformation characteristics of the surrounding rock in tunnels passing through mined-out areas are revealed, a calculation method for the safe thickness of the top plate in tunnels passing through mined-out areas is proposed, standards for controlling blasting vibration in mined-out area tunnels are established, and a controlled blasting construction process for tunnels passing through mined-out areas is created. A complete set of construction technologies for loess tunnels passing through mined-out areas is formed. Achieved safe and stable construction of a loess tunnel undermining an abandoned mining area. 4. Created the construction technology for a loess tunnel undermining buildings. Invention of an improved building settlement measurement device, revealed the stress deformation laws of surface buildings and surrounding rock during the process of a loess tunnel undermining, clarified the vibration law of ground buildings when blasting construction is carried out beneath the tunnel, created a comprehensive construction method and construction process for shallowly buried loess tunnels undermining buildings, achieved the safe passage of a loess tunnel close to surface buildings. 5. Developed the risk information management and control system for loess tunnel construction. Established two risk assessment models suitable for loess tunnel construction based on the improved fuzzy matrix method and fuzzy analytic hierarchy process, created a risk index system and risk control measures for shallow burial and undermining loess tunnel construction, independently developed the risk management information system for loess tunnel construction, The dynamic and informatization of the risk management process have been achieved. The project has resulted in 8 national patents, with 5 granted, and 1 software copyright obtained; published 5 books, written 50 papers, cited a total of 618 times; trained more than 20 graduate students. In recent three years, research achievements have been applied to railway, highway, and subway tunnel construction projects in Shanxi, Inner Mongolia, Shaanxi, Henan, and other provinces, generating an additional direct economic benefit of 1.082 billion yuan, with significant economic, social, and environmental benefits and broad application prospects.