Analysis on Coupling Model of Permafrost Slope Reinforced by Frame Structure with Anchors
(2.Western Engineering Research Center of Disaster Mitigation in Civil Engineering of Ministry of Education, Lanzhou University of Technology, Lanzhou, Gansu, China 730050)
【Abstract】In order to clarify the working mechanism of frame supporting structure with anchors in the cold regions, a coupling mathematical calculation model of heat-moisture-stress was established. The coupling model was analyzed by the finite element method, and a calculation program was written based on the MATLAB software. Besides, the program was verified by the existing experimental research. Through the examples, the distribution laws of the temperature field, moisture field and stress field of the slope and the freeze-thaw action of the supporting structure were obtained. The results showed that the upper part of slope was greatly influenced by temperature, and the active layer was nearly saturated when it melted. And there existed the supersaturated “bubble” at the bottom of slope. In addition, the shear stress in the process of freezing whose maximum value was twice as large as that in the process of thawing was evenly distributed. The slope was stable during this process. While there appeared an abrupt change of shear stress at the interface between active layer and stable frozen soil layer during thawing. The slope was unstable, and the interface was the potential slip surface. In a freeze-thaw cycle, the axial force of anchor bolt, the internal force of column and the horizontal displacement increased first and then decreased, and all of them increased with the increase of the slope height. The laws of structural internal force and horizontal displacement under the three conditions from the largest to the smallest were freezing stage, thawing stage and the initial stage. The axial force at the anchor head in each soil layer dramatically increased during the frost heaving process, while the increase amplitude gradually decreased in the axial direction. In the process of thawing, the anchor force and the internal force of column decreased significantly, with a residual deformation produced. Therefore, when the permafrost slope was supported by frame anchor, the supporting structure was supposed to be designed and calculated under the frost heaving condition.
【Keywords】 road engineering; permafrost slope; coupling model of heat-moisture-stress; frame structure with anchors; freeze-thaw action; MATLAB;
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