The complex mechanical behaviours of steeply inclined and layered surrounding rock in strong and active fault zones result in control measures that cannot adapt to asymmetric squeezing tunnel and are still unsolved. Hence, the Yuntunbao Tunnel was taken as an example to study this issue based on geological survey and indoor and outdoor tests. The results showed that strong geological structures and abundant groundwater undoubtedly deteriorate the mechanical properties of rocks containing many water-sensitive minerals, approximately 45%. The stepwise growth of deformation characteristics before reaching the rock peak strength and the gradient to abrupt failure characteristics after reaching the rock peak strength are determined via triaxial cyclic and static load tests. According to field test results, the unilateral squeezing deformation is severe and greater than 1.5 m, the average extent of the excavation loosening zone is approximately 10 m, and the highest deformation rate reaches 12 cm/d. The gradual and sudden changes in tunnel deformation are demonstrated to be consistent with the postpeak deformation characteristics of layered rock in indoor tests. Moreover, the steel arch exhibits composite failure characteristics of bending and torsion. Finally, reliable and practical controlling measures are suggested, including the optimised three-bench excavation method with reserved core soil, advanced parallel pilot tunnel, long and short rock bolts, and large lock-foot anchor pipe. Compared with tunnel deformation before taking measures, the maximum convergence deformation is reduced from 2.7 to 0.9 m, and the bearing force of the primary support is also reasonable and stable.

When a tunnel passes through the silty clay stratum, disasters such as initial support failure and sudden instability of the face are prone to occur, which seriously affects construction safety and geo-ecology. To find the causes of tunnel deformation failure and propose effective solution measures, this study takes a highway tunnel crossing a powdery clay stratum as the research object. Firstly, the tunnel disaster characteristics were scrutinized through comprehensive on-site research. Subsequently, soil specimens were subjected to triaxial testing and microscopic analysis to discern the underlying causes of initial support damage. Furthermore, various reinforcement strategies were evaluated via numerical simulations. Subsequent to this, the identified reinforcement measures were implemented in the field, and their efficacy was assessed through on-site deformation and force monitoring. The findings reveal that the increased water content of the silty clay and its accumulation at the foot of the arch leads to a lack of load-bearing capacity, while the earth in the arch appears to slip and cut, which is the main cause of the initial support misalignment disaster. After optimization, a reinforcement solution of advanced large pipe shed +1.0 m large arch foot + 6 m of double feet-lock anchor pipes at 70 degrees and 0 degrees is determined. Site deformation and stress tests demonstrated maximum deformation of 13.4 cm, maximum surrounding rock pressure of 164 kPa, and maximum stress in the steel frame of 28.31 MPa, validating the effectiveness of the reinforcement solution.

The increasing mean sea depths have necessitated wind turbine foundation to have larger moment resistance capacity, from early design of monopiles to recent piled jackets. Design-oriented pile-soil interaction model (API t-z model) is modified for cyclic loading with a simple correction factor, with little attention paid to stiffness degradation and displacement accumulation caused by cyclic shakedown and ratcheting. Assisted by a bounding surface plasticity-based cyclic t-z model, this study aims to investigate the influence of t-z modeling on integrated analyses of jacket offshore wind turbines through modifying the open-source OpenFAST software. Demonstrated by the NREL 5 MW offshore wind turbine supported by piled jacket, the results show that the cyclic weakening of pile-soil interface leads to an upright load transfer from the vertical interface of the pile with degraded t-z resistance, to its lateral interface by mobilizing more p-y resistance. Ignorance of the stiffness degradation and displacement accumulation would mis-estimate modal properties, cumulative deformation, loading sharing behavior and stress transfer mechanism significantly, suggesting the model's merits in deformation control and stress transfer for piled jacket in feature design.