摘要:

Foundation investigations for an industrial plant on a thick stratum of preconsolidated, sensitive clay are presented. In spite of the fact that the effective stresses in the clay caused by the building load remained below the average preconsolidation pressure of the clay, the settlement of the buildings locally appreciably exceeded the anticipated order of magnitude. It is shown that a drop in the groundwater level by a few feet would result in the effective stresses exceeding the preconsolidation pressure within the upper portion of the clay stratum. With such an assumption, the consolidation would not be governed by the very flat recompression branch of the consolidation curve, but in part also by the steep virgin compression branch of the consolidation curve. It is concluded that, when dealing with preconsolidated, sensitive clays, the total effective stresses caused by a proposed structure should be kept within a safe margin below the average preconsolidation pressure in order to make provision for any unforeseen load increase such as might arise from a drop in the groundwater elevation.

ISSN:0008-3674    

DOI:10.1139/t65-046

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

The results of studies on the relation between freeze-up, break-up and weather conditions for a small fresh-water lake in the Ottawa area are reported. Techniques using air temperature records for estimating when a solid ice-cover will form on the lake are investigated. .A formula using weather records is also developed for estimating the time taken for ice to melt from the lake. The usefulness of these relationships for estimating “freeze-up” and “break-up” dates for rivers and lakes is discussed.

ISSN:0008-3674    

DOI:10.1139/t65-047

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

Muskeg waters are generally acidic and potentially corrosive to concrete and metal structures. The amount of dissolved salts and free carbon dioxide in the water is an important factor in its aggressive attack on concrete. Although pH measurements are not the only criterion of aggressiveness, they are a reasonable indication in many instances of potential severity. A good defence against an aggressive environment is a high quality, very dense concrete. High alumina concrete and air-entraining agencies provide further protection in extremely aggressive environments. Surface treatments of concrete have not proved to be very successful over a long period of time.Corrosion of metals in a muskeg environment is an electrochemical action; the type and rate of corrosion are functions of the property of the metal as well as the soil and water conditions. Factors such as dissolved salts, pH, total acidity, resistivity, aeration, and presence of anaerobic bacteria influence corrosion. Optimum protection to metals in an aggressive environment is provided by a combination of a surface coating and cathodic protection.

ISSN:0008-3674    

DOI:10.1139/t65-048

出版商:NRC Research Press    

年代:1965

数据来源: NRC

ISSN:0008-3674    

DOI:10.1139/t65-049

出版商:NRC Research Press    

年代:1965

数据来源: NRC

ISSN:0008-3674    

DOI:10.1139/t65-050

出版商:NRC Research Press    

年代:1965

数据来源: NRC

ISSN:0008-3674    

DOI:10.1139/t65-051

出版商:NRC Research Press    

年代:1965

数据来源: NRC

ISSN:0008-3674    

DOI:10.1139/t65-052

出版商:NRC Research Press    

年代:1965

数据来源: NRC

ISSN:0008-3674    

DOI:10.1139/t65-053

出版商:NRC Research Press    

年代:1965

数据来源: NRC

ISSN:0008-3674    

DOI:10.1139/t65-054

出版商:NRC Research Press    

年代:1965

数据来源: NRC

ISSN:0008-3674    

DOI:10.1139/t65-055

出版商:NRC Research Press    

年代:1965

数据来源: NRC