Most geotextiles consist of polymers of polyolefin, polyester or polyamide family, which involve environmental problems related to soil pollution. Geotextiles can be used for at least one of the following functions: Separation, reinforcement, filtration, drainage, stabilization, barrier, and erosion protection. Due to the characteristics of high strength, low cost, and easy to use, geotextiles are widely used in geotechnical engineering such as soft foundation reinforcement, slope protection, and drainage system. This paper reviews composition and function of geotextiles in geotechnical engineering. In addition, based on literatures including the most recent data, the discussion turns to recent development of geotextiles, with emphasis on green geotextiles, intelligent geotextiles, and high-performance geotextiles. The present situation of these new geotextiles and their application in geotechnical engineering are reviewed.

Water inrush hazard seriously threatens construction safety of subsea tunnels in unfavorable geological areas. In recent years, a large number of subsea tunnels have been built worldwide, some of which have experienced many water inrush disasters, especially in Japan and Norway. In this paper, a systematic methodology is proposed to rigorously review the current literature about water inrush in subsea tunnels. Emphasis is placed on recorded causes and evolution processes of water inrush, as well as relevant mitigation measures. In particular, the geological conditions that generate such water inrush hazards are initially discussed by counting cases of tunnel water inrush in the past decades (43 cases of water inrush hazards in tunnels (including mountain tunnels)). The process of formation of failure modes of water inrush, and the corresponding research methods (including theoretical, numerical and experimental) are reviewed, and can be used to pave the ways for hazard prevention and future research. This is followed by a summary of the prevention methods and mitigation measures used in practice, and a short discussion of the achievements and limitations of each method. Then combined with the evolution characteristics of the failure area, the water inrush process of different modes is divided into three stages, with a proposed a grouting scheme for each stage. Finally, concluding remarks, current research gaps and future research directions on subsea tunnel water inrush are provided and discussed.

To fully understand the temperature distribution of cold regions and the variation law of temperature fields in cold‐region tunnels, this paper presents a case‐history study on a tunnel located on the eastern Qinghai‐Tibet Plateau, China. The conclusion is as follows: the temperature outside the tunnel and the ambient temperature are affected by wind speed and light. The law of the temperature field in the tunnel is greatly affected by wind speed and wind direction. According to the field test, the wind speed in the tunnel is about 2.8 m/s in winter, and the daily average temperature at the exit of the tunnel is basically lower than that at the entrance. From the central to the entrance, the temperature in the tunnel decreases by 0.11°C every 10 meters along the longitudinal direction; from the central to the exit, the temperature in the tunnel increases by 0.07°C every 10 meters. In this regard, for the problems of lining frost damage and central drainage pipe freezing, it is suggested to adopt the way of heating and drainage, but heating the freezing area outside the drainage pipe should be avoided. The test results can provide references for the design, construction, and research of the temperature field of the tunnel antifreezing system in the cold region. It is hoped that the test results can be useful in the design and construction of frost damage prevention systems and the investigation of temperature fields in cold‐region tunnels.

Hydraulic compactor is an efficient reinforcement machine for loess subgrade. However, it is difficult to control the layered compaction quality of the subgrade. This research presents a real-time layered compactness monitoring method for hydraulic compactor reinforcement of subgrade in loess areas. The hydraulic force coefficient is first introduced, and the dynamic response model of the hydraulic rammer and soil is established. The relationship between the acceleration of the hydraulic rammer and the compactness of subgrade is then obtained based on the collision theory in elastic half space. A full-scale test using a hydraulic compactor to reinforce loess subgrade was also carried out. Results show that the hydraulic compactor obtains the effective influence depth for the reinforcement of loess subgrade. Within the effective reinforcement depth, the relationship between the peak acceleration of the rammer and the layered compactness of subgrade can be well fitted by a quadratic function model. The layered compactness of the subgrade and the working state of the hydraulic compactor can then be remotely monitored at a mobile terminal in real time. Furthermore, the monitoring technology was applied to Huangling-Yan’an Expressway in China, significantly improving the accuracy and efficiency of real-time monitoring of the layered compactness of subgrade in the loess area.

With the rapid increase in the scale and number of tunnels in cold regions, the frost damage problems, such as cracking of the lining structure under the action of freeze–thaw cycles are becoming increasingly prominent. This review article collects and sorts out the frost damage phenomena that occur in the lining structure of tunnels in cold regions under the action of freezing and thawing cycles, classifies the frost damage phenomena into structural frost damage and non-structural frost damage, and proposes that the research on the mechanism of lining frost damage and its prevention measures should focus on lining cracking. According to the damage degree of the freeze–thaw cycle to the lining structure and its influence on tunnel operation, the cracking mode and cracking stage of lining are introduced. The analysis focuses on the mechanism of cracking in lining structures subjected to freeze–thaw cycles, considering the external force caused by frost heaving, the alteration of mechanical properties in lining concrete, and the internal changes in the microstructure of the concrete. Additionally, the factors that contribute to the occurrence of lining cracking are summarized. Based on this, corresponding control measures have been organized to provide reference for the development of cracking of the lining structure under the action of freeze–thaw cycle.

Techniques including pre‐grouting, long pipe roof, and parameter optimization were employed to ensure the safety of loess metro tunnelling under an existing glass building. Their effects were proved through monitoring the settlement of building and surface during tunnelling. Besides, division of settlement monitoring according to processes, a new method, was conducted to control settlement in time. The highest surface settlement after construction was 16 mm only, meeting the requirement. The result indicates that it is practicable to control the tunnelling settlement strictly in extremely difficult geological areas. The settlement regularities were also studied through numerical simulation; their deformation is larger compared with in situ results while their change trends coincide during most processes. Soil excavations cause settlement primarily, accounting for more than 60%. It is suggested that dual slurry pre‐grouting and process‐based measurement should be employed before each excavation in water‐rich loess areas.