A Study of the Effects of Geosynthetic Reinforced Soil and Reinforcement Length on GRS Bridge Abutment

The geosynthetic reinforced soil (GRS) bridge abutment with a staged-construction full height rigid (FHR) facing and an integral bridge (IB) system was developed in Japan in the 2000s. This technology offers several advantages, especially concerning the deformation behavior of the GRS-IB abutment. In this study, the effects of GRS in the bridge abutment with FHR facing and the effects of geosynthetics reinforcement length on the deformation behavior of the GRS–IB are presented. The numerical models are analyzed using the finite element method (FEM) in Plaxis 2D program. The results showed that the GRS–IB model exhibited the least lateral displacements at the wall facing compared to those of the IB model without geosynthetics reinforcement. The geosynthetics reinforcement in the bridge abutment with FHR facing has reduced the vertical displacement increments by 4.7 times and 1.3 times (maximum) after the applied general traffic loads and railway loads, respectively. In addition, the numerical results showed that the increase in the length-to-height (L/H) ratio of reinforcement from 0.3H to 1.1H decreases the maximum lateral displacements by 29% and the maximum vertical displacements by 3% at the wall facing by the end of construction. The effect of the reinforcement length on the wall vertical displacements is minimal compared to the effect on the wall lateral displacements.

Analysis of the Deformation Characteristics of Vertically Reinforced Subgrades to Address Land Shortage in Railroad Construction

Vertically reinforced subgrade (VRS) the construction of which involves building backfills first and then facing walls was developed for the railroad construction in areas with land shortages, such as civil areas. VRS minimizes the land use during railroad construction and operation. It also reduces residual settlement during railway operation by virtue of its staged construction process. In this study, numerical analysis was performed to quantitatively evaluate the deformation characteristics of VRS, such as surface settlement and horizontal deformation, during the construction and operation of railroads. It was confirmed that VRS with 40 cm of vertical spacing and a reinforcement short length of 0.35H complies with the limit of residual settlement (30 mm) and horizontal deformation (less than 0.03H) for concrete slab tracks, even in the most unfavorable conditions.

Numerical Analysis of Staged Construction of an Embankment on Soft Soil

The objective of this study was to predict the excess pore pressure and settlement of an embankment over soft ground, treated with vertical drain, through numerical analysis of staged construction. To carry out finite element analysis, numerical modeling software PLAXIS 3D was used. The practical demonstration was demonstrated by validating two case studies; the first one was a trial embankment at the Krishnapatnam Ultra Mega Power Project in Nellore, Andhra Pradesh, India and the second one was the Second Bangkok International Airport or Suvarnabhumi Airport, about 30 km from the city of Bangkok, Thailand. After the successful validation of the program, detailed finite element modelling of an embankment resting on soft soil was conducted. Moreover, the degree of consolidation and factor of safety were also determined. There was rapid dissipation of excess pore pressure and maximum settlement at the mid-height of the embankment. In contrast, the dissipation of excess pore pressure was very slow just below the embankment and it increased with the increment of the depth of the clay layer. Moreover, with the rise of the distance from the centre of the embankment, the dissipation of the excess pore pressure also raised and took less time, the settlement also increased.

An Experimental Investigation of Mechanical Properties of Bonded Concrete

This paper presents an experimental study to measure mechanical properties of bonded concrete specimens. The bond between freshly mixed and hardened concrete has been a concern in repair and retrofit projects as well as staged construction of concrete members. This concern has roots in the time-dependent behavior of concrete, beginning with early-age concrete and continuing with long-term performance and durability of concrete. Moreover, environmental conditions generally complicate the behavior of concrete and resulted deformations such as shrinkage and creep. Application of chemical adhesives and epoxies is a common technique to enhance the bond at the interface of old and new concrete elements. The presented methodology includes preparation of bonded specimens with application of grout and adhesive agents. Mechanical strengths of specimens have been reported based on compressive, tensile, flexural, and shear testing. Results indicate that bonding agents are more effective in tensile and shear behavior of bonded samples.