Comparison between temperature based thaw weakening prediction model and field observation methods

• Main Authors: Berglund, Andreas, Edeskär, Tommy, Knutsson, Sven
• Format: Conference Object
• Language: English
• Published: Luleå tekniska universitet, Geoteknologi 2011
• Subjects: Geotechnical Engineering; Geoteknik; Arctic
• Online Access: http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-38064

Structures like roads and port yards located in cold climate are affected by freezing and thawing every year. The global trend of a warmer climate and temperatures around 0°C for longer periods of time will change the freezing/thawing behaviour in many locations. The tendency will changeto have several freezing /thawing cycles in a given location every year. The bearing capacity of low volume roads and simple port yards will be affected by a prolonged thawing period with lower bearing capacity as a consequence. Bearing capacity problems can lead to increased costs for traffic as well as increased maintenance costs. Due to very high costs for destroyed structuresduring thaw, a lot can be gained if bearing capacity problems at a given site can be forecasted well in advance in order not to destroy the structure. Such a method should preferably be based upon simple measurements like air temperatures to make it easy to use also in remote areas. In the described temperature based model air and ground temperatures are used to develop anaccumulated thaw index and corresponding limits. When the thaw index limit is reached, the construction at the evaluated depth thaws, leading to increased pore water pressure and reduction of strength and bearing capacity. This paper presents a study of the application of the model at low volume roads in Sweden. Bearing capacity at the road was evaluated from field tests by falling weight deflectometer (FWD) test carried out 24 times during the thawing season i.e.March 4 through June 9. Predictions made by the model were compared with the subgrade module evaluated from the FWD series. The results show that the model might be possible to use in Sweden and elsewhere if minor adjustments are carried out. Godkänd; 2011; Bibliografisk uppgift: Paper no 11-87; 20121114 (tomede)