考虑石灰桩体胀与地基约束力耦合作用时地基挤密结果的解  

A Solution on Compaction Results of Foundation Considering the Coupled Function between Lime Pile Expansion and Foundation's Force of Constraint

作　　者：米海珍[1] 文桃[1] 刘辉[1] 

机构地区：[1]兰州理工大学土木工程学院,兰州730050

出　　处：《建筑科学》2012年第9期33-39,共7页Building Science

基　　金：甘肃省自然科学基金项目(3ZSO42-B25-031);兰州理工大学校基金项目

摘　　要：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 compaction pile is a common way to treat foundation; it is widely used in the collapsibility loess areas. There were a lot of practices about this type of engineering. But at present this engineering still cannot be designed based on the material property and foundation character. Authors have got the relationship between lime＇s volume expansibility and its confining pressure by the test. Based on the results, authors solved this problem when regarding pile＇s volume expansibility and its confining pressure as a coupling problem, and supposing the soil body has ideal elastic-plastic and obeys C-M yield condition, and using the elastic-plastic theory. Following results are obtained： the Pile-hole pressure depends on the burial depths, soil basic parameters and the expansibility of the lime, and isn＇t related to the radius of the pile hole; the relationship among plastic radius of soil, pressure of the pile hole and burial depth ; the relationship among pressure of the pile hole, displacement of the hole edge and burial depth ; plastic radius of soil and displacement of the hole edge are proportional to the designed radius of the pile hole. After obtaining the above relations, as long as parameters of quicklime expansibility and soil property are obtained through the experiments, engineering design can be done directly, other than depending on the empirical parameters formerly. This paper validates the theoretical formula＇s applicability by two engineering calculation examples. Compared with the previous, these formulas presented in this paper for engineering design are more accurate and reliable than the professional experience and judgment in the past.

关 键 词：地基处理 石灰桩 弹塑性理论 C-M屈服准则 耦合解 

分 类 号：TU472.32[建筑科学—结构工程] TU470.3[建筑科学—土工工程]