Case study of sand bag well applied on soft soil reinforcement in road widening project
Based on the case study of soft soil reinforcement on Baian interchange, Gaofu Road, Shunde District, Foshan, the designing method and monitoring program of sand bag well applied on the soft soil reinforcement in road widening project were introduced systematically. The settlement monitoring results during the preloading process indicated that the raise of the preloading height significantly increased the consolidation and settlement of soft soil ground. The settlemental rate was much greater at the beginning and medium-term of the preloading. While during the later proloading and the followed consolidating period, the settlement rate slowed down obviously. Therefore, it is very important to control the magnitude of each loading grade and the settlement rate at the beginning and medium-term of preloading. It was found that there was a desirable reinforcement effect and economic benefit applying sand bag well method to consolidate the soft soil ground at the case of overpass extension engineering in road widening project. The sand bag well method is valued being applied in similar projects.
Numerical analysis of foundation columns to support widening of embankments
Abstract Increased traffic volume has made it necessary to increase highway capacities by widening embankments and pavements. Adding a new embankment to an existing embankment induces additional stresses and deformations beneath the widened and existing portions of the embankment. Differential settlement may develop between and within the new and existing portions of the embankment, especially over soft soils. This differential settlement often causes pavement distress, such as longitudinal cracks or the drop-off (or sinking) of pavement sections. Different techniques have been adopted to remedy these problems, including the use of foundation columns, such as deep mixed columns, vibro-concrete columns, stone columns, and aggregate piers. However, design procedures for foundation columns constructed for this purpose are not well developed. The analyses of eight cases of column-supported widened embankments and two untreated foundations are presented in this paper. The factors considered include the consolidation of foundation soils under existing embankments and the spacing, region, and modulus of foundation columns. Two-dimensional finite difference software was used after the calibration of the model against a field case study and numerical analyses were conducted to investigate stresses and deformations of the widened embankments over soft soil with or without the remediation of foundation columns. The results presented in this paper include the vertical and the horizontal displacements, the maximum settlements, the transverse gradient change, and the distribution of the additional stresses induced by the widening. Recommendations are made for the design of foundation columns to remedy roadway pavement failure due to widening of embankments.
SYNTHETIC REINFORCEMENT IN THE WIDENING OF A ROAD EMBANKMENT ON SOFT GROUND
When widening a road embankment differential settlements and pavement cracking along the joint between the old and the new parts of embankment appear. Synthetic reinforcement abhors horizontal stresses caused by the weight of the embankment and reduces horizontal displacements and in this way reduces pavement cracking. Theoretical reinforced widening has been examined with FEM (PLAXIS). A full-scale trial structure has also been studied.