软土地区桩端后注浆灌注桩合理注浆量与承载力计算

Estimate of the Reasonable Quantity of Grouting and the Bearing Capacity of Post Base-grouted Bored Pile

桩端后注浆灌注桩单桩合理注浆量与承载力的计算成为工程界关注的主要问题之一,尚无设计规程可循。结合上海地区桩端后注浆灌注桩的工程实践,基于已有研究成果和上海软土地区工程地质条件,提出了物理几何意义明确的合理注浆量公式,并从桩身与桩端扩径的角度提出了桩端后注浆钻孔灌注桩承载力的计算公式。计算方法直观地体现了注浆量对后注浆桩承载力提高的影响,并与所给出的合理注浆量公式相联系,参数便于确定。在上海若干工程中的应用结果表明方法是合理的。

The most interested problems of the design of post base-grouted bored pile are the estimate of the quantity of grouting and the bearing capacity. A formula of the estimate of post grouting, with clear geometrical meaning and matching dimension, is brought out. Then based on the formula, the estimation of bearing capacity of post based-grouted pile is brought out from the point of view of the enlarge of the pile after grouting. The method behaves the affection of quantity of grouting on the bearing capacity of post grouting pile directly. The estimate method of quantity of grouting and bearing capacity is applied in the project of a tall building in Shanghai and gets reasonable result.