Temperature Field Analysis Of Bored Piles In Island Permafrost Region

Permafrost is a complex multi-phase and multi-component system. As the temperature changes, mutual conversion between its solid ice and liquid water occurs, forming complex physical and mechanical properties. Therefore permafrost is very sensitive to temperature changes. The construction in permafrost drilling piles, with the disturbance of foundation construction process and the heat from the inside, will bring greater disturbance to the long-term stability of the permafrost ice. Especially after the completion of the concrete, the temperature of the concrete will gradually rise on account of the impact of concrete hydration heat. With the increases of the temperature, the permafrost concerning with the pile foundation will be affected by the heat conducted from the concrete and its temperature will also increase. With the exchange of heat, the sate of the frozen permafrost will change accordingly and its physical and mechanical properties will change as well. This will have a great impact on the bridge, easily resulting in frost heaving and thaw collapse.This article based on the highway project of Modaxian forest, Combined with the features, such as low temperature and vast temperature variations, of the location of the project (Daxinganling island-shape permafrost zone), and develops an on-site temperature monitoring system for the pile. In addition to overcoming these severe weather problems, the system can also continuously spot the real-time temperature and is able to remotely transmit the temperature data to users; At K216+746 and K205+404 where the two bridge projects are conducted, bored piles are founded. The change of the temperature field can be observed through this test. The floor plan layout of the temperature monitoring system and the temperature features are given; Based on the temperature data from the site, two graphs can be drawn. One is about the inside temperature change of the pile and the other one is about the temperature change of the pile at a depth of 1m and 2m. The change of the temperature of the pile and the soil around the pile, as well as the range of the influence of hydration heat can be detected; A finite element analysis model of the pile temperature is established and the accuracy of the model is tested by the data from the site. Then the model is used to further analyze the distribution of temperature of bored pile and permafrost. The results can provide data support for the optimization of the pile construction process and the acceleration of the project in the island-shape permafrost zone.