Abstract

This study presents a finite element analysis on the behavior of soil nail walls subjected to different freezing and thawing conditions. Thermo-mechanical coupled analysis has become increasingly important due to the increasing number of geotechnical structures built in cold regions. Soil nailing is a relatively new technique of reinforcing existing slopes or supporting new excavations. Its performance has been proven through decades of successful applications throughout the world. However, its applications in cold regions are still very limited due to sparse research available on its behavior in cold regions. In addition, soil may dramatically change its properties after experiencing freezing and thawing cycles. A two-dimensional finite element analysis using ABAQUS software is conducted to investigate the frost penetration depth in the soil and the resulting influence on the performance of the soil nail walls in Northern Ontario. The numerical model is verified against the field measurements obtained from a research program done in Brunswick, Maine, U.S. (Duchesne, 2003). The change of thermally induced stress along soil nails as well as the increase of displacements and earth pressure on the facing of the walls is investigated under freezing conditions. A parametric study is also conducted to probe the effect of thermal insulation systems on the wall facing and nails. This study provides valuable insight into the behavior of soil nailed structures in cold regions.

Highlights

  • Earth structures, such as embankments and slopes, and earth retaining walls, is commonly used in cold regions for transportation and other applications

  • 1.3 Thesis Layout This study presents a numerical simulation of the freezing and thawing cycle on SNWs, followed by recommendations for implementing SNWs in cold regions

  • The model is adapted from Gibson et al (1981) theory, which is considered the variation of permeability and compressibility during thaw consolidation event

Read more

Summary

General

A soil nail is a structural element which transferred loads to the ground to retain excavated or existing slopes. The nail reinforcement developed stability of a slope, by improving the normal force and the soil shear resistance along the potential slip surfaces. The prolonged exposure to freezing temperature may weaken the facing materials, diminish the bonding strength between at the groutsoil interface, and the adhesion between the shotcrete and the soil. This may create additional long-term deformation, and generate excessive stresses on the nails. The propagation of thermal energy inside soil mass, and its associated strain and strength change, is a very complicated phenomenon Both unsaturated and saturated soils may revolve their engineering behaviours due to temperature variations (Gens, 2010). To minimize these detrimental effects, freeze-thaw cycles should be considered in the SNW design

Research Objective
Thesis Layout
Soil Nail Wall
Construction of Soil Nail Wall
Application of Retaining Systems in Cold Regions
Seasonal Stresses on Retaining Systems in Cold Regions
Seasonal Stresses on Soil Nail Walls in Cold Regions
Freezing and Thawing Phenomena in Soil
Mechanisms of Heat Transfer in Soil
Temperature Profile in Ground
Thaw Consolidation and Thaw Settlement in Soil
Previous Investigation on Freezing and Thawing Behavior of Soil
Theoretical Background of Heat Transfer in Soil Nail Walls
Transient Heat Transfer Model in Freezing and Thawing Soil
Frost Penetration Prediction Models
Frost Penetration Modeling for Walls
Mitigation Measures for Preventing Frost Damage on Retaining Structures
Constitutive Models for Freezing and Thawing Soil
Finite Element Code
Details of Finite Element Model for Freezing and Thawing Study
Material Modeling
Selection of Soil Properties for simulation
Steel Nail Model
Concrete Wall
Selection of Element Type and
Loading and Boundary Conditions
Connection of Soil Nails to the Wall
Equivalent Nail-Grout Parameters
Thermal Analysis
Sequentially Coupled Approach
Transferring the Heat Transfer Results to the Mechanical Analysis
Thermal Strain
Solution Procedures
Verification Process
Model Geometry The geometry of the model for the SNW in
Instrumentation
Effects of Freezing and Thawing on Material Properties
Introduction
Effects of Thermal Insulation
Performance of a Hypothetical Soil Nail Wall in Timmins, Ontario
Problem description
Results and Discussion
Summary
Conclusions
Recommendations for Future Research
Full Text
Published version (Free)

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call