Study Of Lateral Pressure Mechanism Between Granular And Bin Of Heavy Vehicle

Heavy-duty and fast are the development direction of the international railway transportation. A rational design to meet the strength requirement is the research hotspots in the manufacture of a heavy duty freight car. Code of TB /T 1335-1996 is the main reference to design of a wagon with the highest speed 120km/h and the largest axle-load 25 t. With the increasing of axle-load and speed, the old code could not meet the design requirement of a heavy-haul freight car. Furthermore, the old code cannot reflect the distribution of the earth pressure on the wall. In view of this, the present paper focuses on the determination of earth pressure on the wall of an open wagon. The main research findings are discussed as follows:The end wall of a wagon is referred as short retaining walls. For sliding surface is a plane surrounded by fracture trajectory, various studies suggest the mechanics of short retaining walls differs from traditional walls and the lateral earth pressures on short retaining walls are no longer properly predicated by using conventional at-rest or active equations. In this paper, based on Mohr circle and limit equilibrium theory, the authors present analytical results from calculations performed to estimate the mechanical response of backfilled openings, emphasizing the effect of load transfer along the interface between the wall and relatively soft backfill.With respect to features, the middle door in the lateral wall of wagon is similar to trap door in Terzaghi experiments. Based on Mohr circle and limit equilibrium theory,an analytical solution of earth pressure is performed to estimate the trajectory of stable arch in backfill, emphasizing the effect of load transfer along the interface between middle door and lateral wall. Then the lateral pressure can be calculated as soon as the volume of sliding wedge is obtained. The results indicate that the arching effects developed in the backfill greatly influence the resultant force on the supporting structure. The analytical results are compared to experimental and the discussion that follows highlights some of the key factors influencing the resultant force on the supporting structures.For the active earth pressure on a wall subjected to both horizontal and vertical seismic inertial forces,it took into account arching effects occurring in the backfill and assumed the formed arch as the arc trajectory of the minor principal stress. Based on the assumption, the lateral pressure coefficients was deduced and applied in differential slice technique to calculate the pressure on the wall, resulant lateral force and location of resultant force. The developed expression was then analyzed for the special cases of experiments. The results of present method were simultaneously compared with the conventional theory of Mononobe-Okabe. The comparison showed that the arching effects have great influence on the distribution of earth pressure on the wall. The location of resultant force is higher than 1/3 of total wall height and increases with the increment of the impact coefficients.Practically all retaining walls rotate, and the soil arching could concur to bring about the result, especially under working conditions. In this paper, an analytical method is presented using a modified differential slice solution of active pressure based on assumption of stress in slices obeying maximum principal shear stress theory, so as the deformation pattern and the arching effects are considered in a simplified manner. Comparisons of calculated results with observations from model tests show that the method can provide a good prediction of lateral pressures for walls rotating about the base. Not only the proposed method reflect nonlinear distribution of pressure,but also deviation is only 5%。...