Measured Soil Thermal Conductivities And Modified Design Curves For Predicting Frost Penetration Adjacent To Insulated Foundations

Methods for predicting frost penetrations are necessary when foundations are placed on frost susceptible soils if problems with frost heave are to be avoided. Graphical methods exist for predicting frost penetration for unheated foundations, however, design information for heated foundations is very limited. Insulation levels on heated foundations will affect the heat loss to the surrounding soil and hence the depth of frost penetration. The paper presents long term measured frost penetration and soil conductivity data for four typical heated residential foundations. Graphical relationships (modified design curves) between frost depths and freezing indices are presented and compared with open field (unheated) conditions.

Calculations using the Neumann solution (as modified by Aldrich) and thermal properties of soils (obtained by Kersten) show that the frost penetration depth for the same freezing index for essentially all soils with any moisture content and for dry sand and rock varies by a factor of about 2 to 1. The extremes calculated in this way bracket the experimentally determined design curve of the US Army Corps of Engineers and give it theoretical support. The theoretical calculations and additional experimental data are used as a basis for a small alteration in the slope of the design curve. This modified design curve is recommended for field use because of (1) inherent imperfections in existing theory and (2) practical limitations to precise specification of field conditions. (Author).

Introductory technical guidance for professional engineers interested in cold regions and arctic engineering. Here is what is discussed: 1. INTRODUCTION 2. FACTORS AFFECTING DESIGN OF FOUNDATIONS 3. SITE INVESTIGATIONS 4. FOUNDATION DESIGN

During recent years, investigations concerning relationships between the depth of frost penetration as well as the temperature of the frost-penetrated soil and the meteorological conditions occurring during a period of slightly varying snow cover or during a period without a snow cover have been made at the Central Geophysical Observatory in Leningrad. With the availability of weather forecasts, the formula obtained in the work may be used also for predicting the individual values. (Author).

The proper depth at which underground structures, including pipelines, water mains and sewers, should be installed has concerned construction and public-utility engineers and contractors for many years. Most specifications for these installations are still based on practical experience and, generally, experience is available. But in the many new construction developments in Canada, the determination of the depth of frost penetration is a difficult problem. A less arbitrary approach is required to determine the required soil cover for the extension of services in existing urban areas. Even within the boundaries of a town, frost penetration may vary from a few inches to several feet. (Author).