目的:基于相似性原理,模拟实际工况中的降温冻结过程;通过室内试验确定最优桩型,并推导冻拔量与冻深的定量关系。创新点:1.进行季节性冻土区螺旋桩的自由冻胀试验;2.根据相似性原理,在室内试验过程中调整冷端温度与几何尺寸以缩短冻结时间;3.推导得到6种桩型冻拔量与冻结深度的定量关系。方法:1.通过相似性原理确定试验条件,模拟实际工况中的降温冻结过程;2.观测此过程中5种螺旋桩型的温度场、冻拔量和土压力随时间的变化规律,并设置一组光滑桩作为对比;3.根据冻拔量大小选取最优桩型,并推导冻拔量与冻深的定量关系。结论:1.螺旋桩冻拔量小于光滑桩,验证了螺旋桩抗冻拔的有效性;采用不同土样有相同规律。2.冻深达到0.9 m的季冻区,双螺旋大叶片桩抗冻拔效果最好;螺旋叶片建议设置在非冻区;冻拔量大小关系为:双螺旋大叶片桩<半螺旋大叶片桩<半螺旋小叶片桩<双螺旋小叶片桩<全螺旋桩<光滑桩。3.得到6种桩型冻拔量与冻深的线性关系。4.土中水开始冻结时土压力增大,含冰量稳定后土压力变化很小。 OBJECTIVE: To simulate the freezing and freezing process in actual working conditions based on the principle of similarity, to determine the optimal pile type through laboratory tests and to deduce the quantitative relationship between freezing and drawing volume and freezing depth. Innovative points: 1. Conduct free frost heave test of spiral pile in seasonal permafrost region; 2. According to the principle of similarity, adjust the temperature and geometry of cold junction in the indoor test to shorten the freezing time; 3. Derive six kinds of pile Quantitative Relationship Between Freezing Depth and Freezing Depth. Methods: 1.Through the similarity principle to determine the test conditions, to simulate the actual conditions of the cooling and freezing process; 2 to observe the process of five kinds of screw pile temperature field, the amount of frozen and earth pressure changes over time, and Set a group of smooth piles as contrast; 3. According to the size of the frozen draft select the optimal pile type, and deduce the quantitative relationship between the amount of frozen and drained. Conclusions: 1. The amount of frozen piles extracted is less than that of smooth piles, which verifies the effectiveness of spiral piles in antifreeze; the same rule applies to different soil samples. 2. Frozen depth of 0.9 m in the quiescent area, double-helical large leaf pile antifreeze pull the best; spiral leaf is recommended to set in the non-frozen zone; the amount of the relationship between the size of the cold-rolled double helix large leaf pile Pile