![]() Afin de déterminer les caractéristiques de contrainte–déformation du sol granulaire sous un chargement à haute fréquence, un montage d’essai triaxial a été modifié pour étudier les effets de l’accélération et de la durée du chargement, de la teneur en eau, de la fréquence de vibration, de la pression des cellules et de la densité initiale du sol. Le comportement dynamique à long terme de la plate-forme et les performances de service des voies à grande vitesse sont donc affectés. L’augmentation de la vitesse d’exploitation des trains à grande vitesse entraîne souvent une augmentation de la fréquence de chargement du sol de la plate-forme. At high vibration acceleration, the strain amplitude could increase, eventually leading to a collapse of the specimen. A threshold acceleration a = 0.02 g is observed, below which the changes in the shear strength and volumetric strain induced by vibration are negligible. The reduction in strength and strains are found to depend on the loading acceleration and effective cell pressure, but independent of the loading duration, water content, frequency, and initial density. The stress reduction, strain compression, and excess pore pressure are found to vary linearly with vibration acceleration when a/ g > 0.02, where a is vertical vibration acceleration and g is gravitational acceleration. The reduction in axial stress is as high as 40%, and that of volumetric strain, which is permanent, could approach 0.1%. The experimental results indicate that there are reductions in axial stress and volumetric strain during high-frequency loading. To determine the stress–strain characteristics of granular soil under high-frequency loading, a triaxial test setup was modified to investigate the effects of loading acceleration and duration, water content, vibration frequency, cell pressure, and initial soil density. Hence, the long-term dynamic behavior of the subgrade and the service performance of high-speed tracks are affected. Moreover, the proposed method eliminates the need of using other devices like displacement sensor or strain gauges to obtain low-frequency components.An increase in the operation speed of high-speed trains often leads to an increase in the loading frequency on subgrade soil. This paper makes full use of three-axis accelerometers to estimate vehicle's static and dynamic load considering the vehicle's passing route, thus solving the nonlinear problem caused by vehicle's transverse position. ![]() The feasibility of the proposed method is proved through numerical simulation and an experimental test on a bridge. Even though only accelerometers are employed as sensors, the bridge vertical acceleration can capture the dynamic load components and the inclination obtained from the projection of the gravitational acceleration in the longitudinal direction can capture the low-frequency component. In this paper, a method based on an extended Kalman filter is proposed to identify vehicle static and dynamic load only from responses recorded by portable accelerometers, together with their transverse position, which affects the identification of the loads. Both effects need to be properly evaluated because the vehicle static weight is a governing factor in determining bridge's fatigue life while the dynamic part of the vehicle load tends to amplify the bridge responses. The static effect usually indicates the pseudo-static responses of the bridge caused by the vehicle gross weight while the dynamic effect means dynamic responses due to vehicle and bridge dynamic properties and bridge pavement roughness. The effects from passing vehicle's load on bridge are divided into two categories: static effect and dynamic effect.
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