In this study, the results of 1-g shaking table tests performed on small-scale flexible cantilever wallmodels retaining composite backfill made of a deformable geofoam inclusion and granular cohesionlessmaterial were ...In this study, the results of 1-g shaking table tests performed on small-scale flexible cantilever wallmodels retaining composite backfill made of a deformable geofoam inclusion and granular cohesionlessmaterial were presented. Two different polystyrene materials were utilized as deformable inclusions.Lateral dynamic earth pressures and wall displacements at different elevations of the retaining wallmodel were monitored during the tests. The earth pressures and displacements of the retaining wallswith deformable inclusions were compared with those of the models without geofoam inclusions.Comparisons indicated that geofoam panels of low stiffness installed against the retaining wall modelaffect displacement and dynamic lateral pressure profile along the wall height. Depending on the inclusioncharacteristics and the wall flexibility, up to 50% reduction in dynamic earth pressures wasobserved. The efficiency of load and displacement reduction decreased as the flexibility ratio of the wallmodel increased. On the other hand, dynamic load reduction efficiency of the deformable inclusionincreased as the amplitude and frequency ratio of the seismic excitation increased. Relative flexibility ofthe deformable layer （the thickness and the elastic stiffness of the polystyrene material） played animportant role in the amount of load reduction. Dynamic earth pressure coefficients were compared withthose calculated with an analytical approach. Pressure coefficients calculated with this method werefound to be in good agreement with the results of the tests performed on the wall model having lowflexibility ratio. It was observed that deformable inclusions reduce residual wall stresses observed at theend of seismic excitation thus contributing to the post-earthquake stability of the retaining wall. Thegraphs presented within this paper regarding the dynamic earth pressure coefficients versus the wallflexibility and inclusion characteristics may serve for the seismic design of full-scale retaining walls withdeformable polystyrene inclusions. 2014 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting byElsevier B.V. All rights reserved.展开更多
Felids,during intense activities such as jumping and sprinting,adjust their posture by twisting and stretching their body to disperse limb impact and minimize injury.This self-stabilization mechanism has garnered sign...Felids,during intense activities such as jumping and sprinting,adjust their posture by twisting and stretching their body to disperse limb impact and minimize injury.This self-stabilization mechanism has garnered significant attention for inspiring biometric robot design.This study investigates the flexibility and cushioning characteristics of a cat’s spine,focusing on its biomechanical properties.A high-fidelity 3D model was used to test the range of motion(ROM)under six conditions,simulate dorsiflexion to analyze stress distribution.The torsional and compressive stiffness were tested by using five cat spinal specimens.the flexibility principles of the flexible cat’s spine were explained via morphological insights.Results indicate that the cat spine has the least rotational stiffness in axial rotation,followed by extension and lateral bending,with a compressive stiffness of 53.62±4.68 N/mm.Stress during dorsiflexion is evenly distributed across vertebrae.The vertebrae heights account for 90.34%of total spinal length with a mean height-to-width ratio of 1.04.Cats’spines,with more articulations and elongated vertebrae,allow for significant twisting and bending,aiding in rapid body posture adjustments and impact mitigation.These biomechanical traits could inspire the design of robots for confined rescue operations.展开更多
文摘In this study, the results of 1-g shaking table tests performed on small-scale flexible cantilever wallmodels retaining composite backfill made of a deformable geofoam inclusion and granular cohesionlessmaterial were presented. Two different polystyrene materials were utilized as deformable inclusions.Lateral dynamic earth pressures and wall displacements at different elevations of the retaining wallmodel were monitored during the tests. The earth pressures and displacements of the retaining wallswith deformable inclusions were compared with those of the models without geofoam inclusions.Comparisons indicated that geofoam panels of low stiffness installed against the retaining wall modelaffect displacement and dynamic lateral pressure profile along the wall height. Depending on the inclusioncharacteristics and the wall flexibility, up to 50% reduction in dynamic earth pressures wasobserved. The efficiency of load and displacement reduction decreased as the flexibility ratio of the wallmodel increased. On the other hand, dynamic load reduction efficiency of the deformable inclusionincreased as the amplitude and frequency ratio of the seismic excitation increased. Relative flexibility ofthe deformable layer （the thickness and the elastic stiffness of the polystyrene material） played animportant role in the amount of load reduction. Dynamic earth pressure coefficients were compared withthose calculated with an analytical approach. Pressure coefficients calculated with this method werefound to be in good agreement with the results of the tests performed on the wall model having lowflexibility ratio. It was observed that deformable inclusions reduce residual wall stresses observed at theend of seismic excitation thus contributing to the post-earthquake stability of the retaining wall. Thegraphs presented within this paper regarding the dynamic earth pressure coefficients versus the wallflexibility and inclusion characteristics may serve for the seismic design of full-scale retaining walls withdeformable polystyrene inclusions. 2014 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting byElsevier B.V. All rights reserved.
基金funded by the Guangdong Basic and Applied Basic Research Foundation(2023A1515110378)the National Natural Science Foundation of China(Nos.12402368).
文摘Felids,during intense activities such as jumping and sprinting,adjust their posture by twisting and stretching their body to disperse limb impact and minimize injury.This self-stabilization mechanism has garnered significant attention for inspiring biometric robot design.This study investigates the flexibility and cushioning characteristics of a cat’s spine,focusing on its biomechanical properties.A high-fidelity 3D model was used to test the range of motion(ROM)under six conditions,simulate dorsiflexion to analyze stress distribution.The torsional and compressive stiffness were tested by using five cat spinal specimens.the flexibility principles of the flexible cat’s spine were explained via morphological insights.Results indicate that the cat spine has the least rotational stiffness in axial rotation,followed by extension and lateral bending,with a compressive stiffness of 53.62±4.68 N/mm.Stress during dorsiflexion is evenly distributed across vertebrae.The vertebrae heights account for 90.34%of total spinal length with a mean height-to-width ratio of 1.04.Cats’spines,with more articulations and elongated vertebrae,allow for significant twisting and bending,aiding in rapid body posture adjustments and impact mitigation.These biomechanical traits could inspire the design of robots for confined rescue operations.
