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石灰桩是一种常用的地基处理方法,尤其是在湿陷性黄土地区使用广泛。该工程问题的实践已有很多,但目前仍不能完全根据地基的土质特性和材性来进行求解设计。作者曾通过实验得到了生石灰体积膨胀率与其约束力之间的关系。本文在此试验结果的基础上,将桩体膨胀率和桩周土体的约束力视为一个耦合问题来探讨该计算理论,并认为土体具有理想弹塑性且服从C—M屈服条件,利用弹塑性理论求解。由此得到:桩周土体约束力(桩孔压力)取决于生石灰的膨胀性能、土质参数及埋深,而与桩孔半径无关;桩孔塑性半径、桩孔压力及埋深三者的关系;孔边位移、桩孔压力及埋深三者的关系;桩孔塑性半径及水平位移均与桩孔半径成正比。得到以上关系后,只要通过实验测得生石灰料的膨胀参数和土质参数就可进行工程设计,而不是之前的根据经验估计布桩间距和桩体积膨胀率来进行设计。文中还通过实例计算验证了该理论公式的合理性和可靠性,利用文中推导公式进行设计较以往的经验判断更为准确可靠。
Lime pile is a commonly used method of foundation treatment, especially in collapsible loess area. The practice of this project has been a lot of practice, but still can not be completely based on the foundation of the soil properties and materials to solve the design. The author has experimentally obtained the relationship between the volumetric expansion rate of lime and its binding force. Based on the experimental results, this paper considers the calculation of the swelling ratio of the pile and the binding force of the soil around the pile as a coupling problem, and considers that the soil has the ideal elasto-plasticity and complies with the C-M yield condition, Elastic-plastic theory solution. The results show that: the binding force of soil around the pile (the pressure of pile hole) depends on the expansion property of lime, soil parameters and depth, but has nothing to do with the radius of the pile; the plastic radius of pile hole, the pressure of pile hole and the depth of the pile ; Hole edge displacement, pile hole pressure and depth of the relationship between the three; pile plastic radius and horizontal displacement are proportional to the pile hole radius. After the above relationship is obtained, the design of the project can be done as long as the expansion parameters and the soil parameters of the quicklime measured by the experiment, rather than the previous estimation of the pitch of the pile and the volume expansion rate of the pile. In the paper, the rationality and reliability of this theoretical formula are also verified by examples. It is more accurate and reliable to use the formulas derived from the text to design than previous experience.