Although quasi-rectangular tunnels have been widely used in underground projects, there is no related research work that was carried out to design this kind of tunnel excavated in the rock masses that followed the Hoek–Brown (HB) criterion. By transforming the strength parameters of the rocks that obey the HB failure criterion into equivalent strength parameters of the Mohr–Coulomb (MC) criterion, the lining internal forces of a quasi-rectangular tunnel are investigated in this manuscript in light of bending moments and normal forces using the Hyperstatic Reaction Method (HRM). After comparing with the values of a model test and verifying the present method, the influence of different tunnel depths, H, different rock unconfined compressive strengths, ${\sigma }_{ci}$, and the geological strength parameter GSI on the lining internal forces of the quasi-rectangular tunnel is then investigated. The obtained results indicate that the parameters H, ${\sigma }_{ci}$, and GSI have a significant effect on the lining internal forces of the quasi-rectangular tunnel. The work presented in this paper provides a theoretical reference for designing the quasi-rectangular tunnel support structure built in the rock masses following the Hoek–Brown criterion.

The offshore wind industry is expanding from shallow water to deep water. As a cost-effective and efficient anchoring solution, drag embedment anchors have been widely used for mooring floating offshore structures. However, there is currently no well-established method for predicting the installation trajectory and holding capacity of drag anchors in sand. This paper reports an integrated anchor–chain–soil large-deformation finite-element model for simulating the complete installation of drag anchors in sand. The proposed approach restores the effects of anchor chains and detailed structures of the anchor, which is essential for detailed anchor design. Sensitivity analysis is conducted to investigate the convergence of model parameters. The performance of the numerical model is benchmarked against a centrifuge test conducted at the University of Western Australia (UWA), which demonstrates satisfactory accuracy and reliability. Installation simulations are then performed using a popular commercial anchor design in sands of different friction angles. Three characteristic stages during the drag embedment process are identified. The results highlight the significant influence of the soil resistance to the shank on the anchor penetration performance. The large-deformation analysis approach proposed provides a powerful tool for further investigation on drag anchor installation behavior in sand.

Drag embedment anchor (DEA) constitutes a compelling anchoring solution for an array of floating structures, attributable to its exceptional efficiency in holding capacity and the comparatively modest expenditures incurred in manufacturing and installation. The holding capacity of DEAs is, to a large extent, dictated by the penetration depth achieved during installation. In hard soils, such as dense sand and stiff clay, the penetration depth of DEAs is often limited due to the large soil resistance acting on the shank structure, which in turn limits its holding capacity. In this paper, a novel anchor design with a single flat shank is proposed, which can greatly reduce the soil resistance on the shank during installation, in the hope of improving the penetration depth and consequently the holding capacity of DEAs. To verify this design assumption, a comprehensive suite of large deformation numerical simulations is carried out in both clayey and sandy soils. In addition, a series of physical model tests are performed in uniform sand. The results from both the numerical simulations and the model tests confirm the superior penetrability and holding capacity of the proposed single-shank anchor design.