Two-dimensional transient thermal analysis of drilled-pile wall exposed to extreme temperatures and discussion on frost mitigation methods

This paper analyzes earth-retaining walls made of drilled or bored large-diameter steel piles filled with concrete subject to Nordic temperature loads, especially focusing on Finnish temperature conditions and their effects and mitigation methods. Two-dimensional numerical analysis is carried out with Finite Element Method (FEM) software Comsol Multiphysics 6.1. The result’s order of magnitude is validated by a literature review and by a one-dimensional analytical model. The paper aims to understand the frost depths with and without thermal insulation and to find their optimal locations. Results show that the thermal insulation layers might not give the intended benefits if the thermal bridges are not mitigated carefully. Moreover, it is evident from analysis that the horizontal part of the insulation covering the top of the ground plays an important role in decreasing the frost depth. The important findings will help designers reduce material waste, save public money in big infrastructure projects, and preserve the environment.