Study on Temperature Field of Refreezing Process of Static Drill Rooted Pile in Permafrost Regions
Based on the theory of heat transfer,a partial differential equation and boundary condi-tions for the temperature field of pile-soil were listed,and combined with the geological background of low temperature stable permafrost area,finite element numerical analysis was used to seek the solution.The distribution and variation of the temperature field of pile soil during the process of static drilling rooted pile refreezing were analyzed,and the influence of cement dosage and initial mixing temperature of cement slurry on the refreezing process was discussed.The results show that the temperature of pile and soil within 2 m below the surface was significantly affected by the atmospheric temperature,the hydration heat had little effect on the temperature beyond 1.5 times the pile diameter and within 1～2 m below the pile bottom,and after 17 d,the temperature of pile side was frozen to 0℃,and after 27 d,the temperature of pile side dropped to below-0.5℃.When the initial mixing temperature of cement paste increased by 5℃,the refreezing time increased by 5～6 d and the refreezing time was shortened 1～2 d for every 10%reduction in cement dosage.The temperature field of the static drill rooted pile was also affected by the hydration heat,but the refrozen time was shorter.By adjusting the cement slurry mix ratio and reducing the initial mixing temperature of cement paste,the requirements for ce-ment soil strength and refrozen time could be met,thereby improving the bearing capacity and shorten-ing the construction period.
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