刚性桩复合地基侧向土压力试验研究

Experimental study of lateral earth pressure of rigid pile composite foundation

通过室内模型试验，实测得到试验条件下，天然地基和刚性桩复合地基作用在不允许有位移的刚性挡土墙上的侧向土压力；通过与天然地基对比分析，获得了刚性桩复合地基的侧向土压力特性及分布规律。结果表明，刚性桩复合地基中桩的参与（包括桩的荷载深层传递作用、桩负摩擦区的影响和桩体对桩间土水平附加应力的“遮拦”作用等）使复合地基侧向土压力大小和分布规律明显区别于天然地基；在给定荷载水平下，刚性桩复合地基的侧向土压力值低于天然地基，侧向土压力影响范围较天然地基作用位置更深；在试验条件下，刚性挡土墙距离建筑物0．35～1．4 m范围内，当荷载水平达到地基承载力特征值时，刚性桩复合地基作用在刚性挡土墙上的总土压力和附加土压力约为天然地基的43．3％-80．1％和15．9％-59．8％。

Through the indoor model tests, lateral earth pressures exerted by natural foundation and rigid pile composite foundationagainst rigid retaining walls without any displacements are measured. The distribution of lateral earth pressures of rigid pilecomposite foundation is obtained by the comparison with that of natural foundation. It is believed that participation of pile in rigidpile composite foundation makes magnitude and distribution of lateral earth pressure different from natural foundation. In this place,pile participation includes the deep transfer function of pile load, the influence of pile negative friction and the pile ＂block＂ effect onlevel additional stress of soil between piles. The influence range of lateral earth pressure of rigid pile composite foundation withsurcharge is deeper than that of natural foundation. Besides, the value of lateral earth pressure of rigid pile composite foundation issmaller than that of natural foundation at the same location under the same subgrade pressure. In the test conditions of this study, thetotal and the additional earth pressure exerted by the rigid pile composite foundation on the rigid retaining walls are about43.3%-80.1% and 15.9%-59.8% of the total earth pressure of the natural foundation respectively when the load level reaches thecharacteristic value of the foundation capacity within the range of 0.35 to 1.4 m from the rigid retaining wall to the building.