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.
On Distress Characteristics and Mechanism in Road Widening Engineering
When the width of a road is insufficient to meet current National Highway Standards or the need of increased traffic loading, it will be widened. But some facility distresses often appear in road widening engineering, especially the pavement distresses near the position of existing-widening subgrades integration. Several existing widened roads in Chongqing and Shanghai were chosen to investigate the facility distresses in road widening engineering. Based on the investigation and a classification of the combining modes between the existing subgrade and the widening one,the distress characteristics and mechanism in road widening engineering are proposed in this paper. It is shown that the distress resulted essentially from the instable integration and the incoordinate deformation between the existing subgrade and the widening one.
EMBANKMENT WIDENING WITH THE GAP-METHOD
The performance of the so-called gap-method for road widening on soft soil has been studied in the test sections along Dutch highway A2. The gap-method is a two-stage fill operation, aiming at the reduction of damage to the existing road. Measurements did not reveal a permanent positive effect of the gap-method as compared to the standard one-stage fill method. The test sections were modeled in finite-element calculations using Mohr-Coulomb and cap type constitutive relations for the soft soil. The predictive power of the calculations appeared to be limited, the Mohr-Coulomb model giving the best fit to measurements.