Additional Stress in Soil Embankments Subjected to a New Prestressed Reinforcement Device

Abstract

Theoretical solutions were derived to calculate the additional stress/prestress in a newly-developed prestressed embankment (PE), and the diffusion characteristics of the prestress in a PE with a lateral pressure plate (LPP) having width of 0.9 m were clarified using the theoretical solutions and a 3D finite element analysis. The results show that (1) the application of the theoretical solutions requires the net spacing between the LPP and the embankment shoulder is greater than the LPP width; (2) the maximum prestress appears in the upper part of the loading area of a LPP, and the maximum and minimum prestresses present an order of magnitude difference at the shallow depth, but the difference attenuates and the prestress gradually tends to be uniform with increasing depth; (3) the prestress propagates to the core zones that mainly bear the train loads with certain peak stress diffusion angles, and the values for the analyzed case are 50° and 58° in the external regions of the LPP along the slope and longitudinal directions, respectively; and (4) a continuous, effective and relatively uniform prestressing protective layer with a prestress coefficient greater than 0.1 can be formed above the core zones when the LPP spacing is properly designed.

Dynamic Response Characteristics of Railway Subgrade Using a Newly-Developed Prestressed Reinforcement Structure: Case Study of a Model Test

“…After years of research, many useful analytical methods associated with prestressed subgrade have been proposed, including investigations into the diffusion characteristics of additional stresses of prestressed embankment in the directions both perpendicular and horizontal to the slope [ 5 , 6 ], the establishment of a simple stability analysis method for prestressed subgrade considering the additional stress propagation effect [ 7 ], the technical realization of the PRS in a numerical simulation and further investigation into the mechanical and deformation characteristics of a prestressed railway embankment in the static working state [ 8 ], and an optimal design method of the layout spacing for multiple LPPs [ 9 ]. These studies have mainly focused on the statics condition, but studies on the dynamic response of prestressed subgrade have not been prominent.…”

Evaluation of Critical Dynamic Stress and Accumulative Plastic Strain of an Unbound Granular Material Based on Cyclic Triaxial Tests

“…The serviceability of railway tracks is strongly associated with the dynamic stability of unbound granular layers atop weaker layers of the subgrades, of which the critical dynamic stress ( σ cri ) and accumulative plastic/permanent stain ( ε p ) are primary indicators regarding the dynamic stability of unbound granular materials (UGMs) [ 1 , 2 , 3 , 4 , 5 , 6 ]. Subgrades of railways accumulate permanent settlement under dynamic traffic loading, and excessive accumulative surface settlement typically causes problems, such as vehicle turbulence in transition sections [ 7 , 8 ], uneven settlement [ 9 , 10 , 11 ], and lateral expansion of embankment shoulders [ 12 , 13 , 14 ]. One of the most effective ways to control the accumulative deformation of subgrades is maintaining the traffic-induced dynamic stress to be less than a critical value (i.e., the σ cri ), under which the development rate of ε p gradually decreases and can ultimately cease with an increase in the dynamic loading cycles [ 5 , 15 , 16 ].…”