刚性桩复合地基桩间土拱效应分析及桩土应力比计算

Analysis of the Soil Arching Effect Between Piles of Rigid Pile Foundation and Calculation of the Pile-soil Stress Ratio

通过分析刚性桩复合地基桩土相互作用机理,对桩间土拱效应及中性面上桩土应力比进行了研究。刚性桩复合地基工作时,桩间土满足竖向成拱的条件,在桩体中性面上形成竖向三维土拱,其承担的部分荷载通过三维土拱传递至桩体,桩土应力比在中性面上达到最大。通过对桩间三维土拱进行力学分析和计算,得到桩间土通过土拱传递至桩体的荷载表达式,并推导出刚性桩中性面上桩土应力比的计算公式。研究表明,中性面上桩土应力比与土体内摩擦角、黏聚力、桩土摩擦角、桩径、桩长、桩侧摩阻力等参数成正比,与桩间距成反比。计算公式经工程实例验证,有较好的吻合性。

By analyzing the mechanism of pile-soil interaction of rigid pile composite foundation, soil arching between piles and pile-soil stress ratio in the neutral surface are studied. When the rigid pile composite foundation works, the soil between piles meets the conditions of vertical arch and will form a vertical three-dimensional soil arch in the neutral surface of the pile. Part load which soil between piles bears passes to the pile though the three-dimensional soil arch and the pile-soil stress ratio reaches the maximum in the neutral surface. Through the mechanics analysis and calculation of the three-dimensional soil arch between the piles, the authors get the calculation formula of the load which transfers from the soil arch to the pile body and obtain the calculation formula of the pile-soil stress ratio in the rigid pile＇ s neutral surface. Studies have shown that the pile-soil stress ratio in the neutral surface is proportional to the internal friction angle of soil, cohesion, pile-soil friction angle, pile diameter, pile length, pile side friction etc and inversely to the pile spacing. After being tested by the engineering projects, the calculation formula can be used as a reference for the design of rigid pile composite foundation.