The objective of this case study is to evaluate the development of soil arching in an embankment being widened. In two test sections, earth pressures at different locations were monitored to reveal the load redistribution mechanism due to soil arching. Tensile forces in uniaxial plastic geogrids were measured to evaluate the performance of geosynthetic reinforcement in the widened embankment. The soil arching effect was quantified in terms of stress concentration ratio, soil arching ratio and geomembrane effect. Several existing methods were selected to compare with the measured results. The results of the field tests indicate that a two-dimensional plane soil arch with some eccentricity affects the fill load distribution on pile caps and subsoil between piles, and a realistic critical arch height of less than 2.0 m with a ratio of 1.4 times the pile clear spacing was identified. Although few existing methods could generate close results comparable to the measured values, most of the methods overestimated the load carried by the geosynthetic layer. The results also suggest that the foundation soil reaction underneath the geosynthetic layer should be taken into account in the load transfer mechanism of geosynthetic-reinforced and pile-supported widened highway embankments.

Plant fibers, characterized by their low density, renewable nature, and environmentally friendly characteristics, offer considerable potential as reinforcement materials in geopolymer composites. This review provides a critical and thorough examination of recent developments and emerging trends in plant fiber-reinforced geopolymer concrete (PFRGC). The paper commences by detailing the inherent characteristics of plant fibers and the mechanisms governing their interfacial adhesion with the geopolymer matrix, with specific emphasis on the impact of fiber surface modification on interface properties. The review offers a comprehensive investigation of the mechanical properties of plant fiber-reinforced geopolymer concrete, encompassing compressive strength, tensile strength, and toughness. Additionally, the paper examines the influence of plant fiber integration on the durability of geopolymer concrete, discussing improvements in freeze-thaw resistance, permeability, and carbonation resistance. In conclusion, this review highlights the prevailing challenges in the domain and provides insights into future developments of plant fiber-reinforced geopolymer concrete. An analysis was performed utilizing papers from 2000 to 2025 indexed in prominent databases including Web of Science, Scopus, and ScienceDirect to enhance the review. Integrating plant fibers into developing technologies, such as 3D printing of geo-polymer matrices, signifies a promising avenue for structural applications. It advocates that future research efforts should focus on enhancing fiber modification techniques, exploring novel fiber materials, and doing thorough assessments of long-term performance.

Strain hardening cementitious composite (SHCC) and fiber reinforced mortar (FRM) are considered as suitable for strengthening reinforced concrete (RC) structures, both of which belong to fiber reinforced cementitious composite (FRCC), whereas the distinctive strengthening effects of RC structure using SHCC and FRM have not been sufficiently understood until now. In this study, the comparative study of RC members with flexural strengthening using SHCC and FRM is implemented, focusing on the load carrying capacity and ductility improvement of the strengthened RC member. The result demonstrates that the load carrying capacity of the RC member, even strengthened with a plain SHCC layer, can be improved from that of the RC member with strengthening using a steel-reinforced FRM layer, and the ductility of the RC member with strengthening using a steel-reinforced SHCC layer is significantly improved from that of the RC member with strengthening using plain SHCC layer, because the multiple fine cracks in the SHCC layer are obviously increased even with a low-reinforcement-ratio steel bar adopted in the SHCC layer.

This paper presents a systematical numerical investigation into the lining performance of a tunnel with cavities around surrounding rocks, focusing on the influences of cavity size and multicavity distribution. The study demonstrates that the cavities around surrounding rocks have much influence on tunnel stability and may induce damages in tunnel structures, in which cavity width has a more severe effect on the stress state of tunnel structures than cavity depth. Moreover, the numerical investigation also illustrates that the nonadjacent distribution of multicavities has more serious influence on tunnel structures than that from adjacent distribution of multicavities as well as that from a single cavity.

Single-layer tunnel lining using shotcrete has the significant advantages of reducing the tunnel excavation volume and saving construction materials, which has been gradually applied in tunnel construction. The high-performance concretes are generally adopted in single-layer tunnel lining for enhancing the bearing capacity of the tunnel lining, whereas the single-layer tunnel lining may still induce damages due to the adverse conditions such as shallow buried depth of the tunnel, and further study related to its application condition is thus required. This paper presents a study of the single-layer tunnel lining with shotcrete employed for supporting the large-span tunnel, in which the reinforcement ribs are also adopted in the single-layer lining for improving the lining stiffness and strength. The study is implemented using numerical simulation, focusing on the safety and performance variation of the single-layer tunnel lining influenced from the varied lining thicknesses and shallow buried depths of the tunnel. The results shows that the single-layer tunnel lining has the obvious advantage of toughness in significantly absorbing large deformation of surrounding rocks and improving the ability to resist lining cracking. The results also demonstrate that the single-layer tunnel lining with shotcrete and reinforcement ribs can safely support the large-span tunnel, in which the stability and safety of the large-span tunnel are confirmed from both the tunnel deformation and lining stresses. Moreover, the factors related to both the lining thickness and shallow buried depth of the tunnel have great influence on the single-layer tunnel lining with shotcrete and reinforcement ribs, in which the insufficient lining thickness and excessive shallow buried depth of the tunnel can induce the damages of the single-layer tunnel lining due to shotcrete stresses exceeding its strength. This study provides some references of employing the single-layer tunnel lining with shotcrete and reinforcement ribs for supporting large-span tunnel.