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通过模型试验,对不同温度条件(室温条件(20℃)、冻结条件(-10℃)、融土条件)下的饱和砂土分别进行桩头位移-水平荷载关系、桩身弯矩和挠度分布规律以及土体的刚度变化等桩-土相互作用等的研究。此外引入工程中常用的m法进行对比验证,探讨m法的适用条件。研究发现:室温土中桩在小荷载作用下产生明显的桩头侧移和挠曲变形,桩身弯矩呈现自上而下先大后小的分布规律;冻土中形成的大量冰胶结物使土体刚度得到极大提高,大荷载难以使桩基发生大的变形和侧移,桩身最大弯矩埋深显著减小;上层融土降低了桩头位置土的刚度,使得桩显示出室温土与冻土的双重性质,桩身弯矩最大值较室温土、冻土条件下更大,其埋深较冻土中大;在多年冻土区进行桩基施工应当重视冻土层的保护;m法在常温土中具备很好的安全性和适用性,但在冻、融环境下应用时差异较大。
Through the model test, the pile head displacement-horizontal load relationship, pile bending moment and deflection distribution under different temperature conditions (room temperature condition (20 ℃), freezing condition (-10 ℃) and earth melting condition) Law and soil stiffness changes such as pile-soil interaction and so on. In addition, we introduce the commonly used m method in engineering to compare and verify, and discuss the applicable conditions of m method. The results show that the pile at room temperature produces obvious pile head lateral deflection and deflection under small load, and the bending moment of pile body presents a small distribution pattern from top to bottom first, then small and large; So that the stiffness of the soil is greatly improved. It is difficult for the large load to make large deformation and lateral displacement of the pile, and the maximum buried depth of the pile body is significantly reduced. The upper thawing soil reduces the stiffness of the soil at the pile head so that the pile shows The dual nature of soil temperature and permafrost is that the maximum bending moment of pile body is larger than that under room temperature and permafrost conditions, and the buried depth is larger than that of frozen soil. When constructing pile foundation in permafrost region, Protection; m law at room temperature in the soil with good safety and applicability, but in the freezing and thawing environment, the application of large differences.