长短刚性桩复合地基桩、土承载性状与厚径比相关关系试验研究

通过室内模型试验，实测得到了在等厚径比条件下，长短刚性桩复合地基长桩、短桩、桩间土的承载力发挥系数，得到了长桩、短桩、桩间土承载性状与厚径比的相关关系，长短刚性桩复合地基采用等厚径比，使长桩、短桩和桩间土承载力都得到充分发挥是很困难的，且短桩承载力发挥较长桩更为充分。在等厚径比试验结果基础上，对长短刚性桩复合地基变厚径比设计进行了研究探讨，认为长短刚性桩复合地基宜采用变厚径比设计，降低长桩厚径比、提高短桩厚径比，让长桩厚径比小于短桩。变厚径比设计可采用等褥垫厚度变桩径（长桩桩径取大值）或等桩径变褥垫厚度（长桩选用较薄褥垫）来实现。

Experimental study on pile-soil bearing behavior and thickness-diameter ratio of composite foundation with long and short piles

The bearing behavior of long pile and short piles, load sharing ratio of soil between piles, pile-soil stress ratio and mobilization factor of bearing capacity are measured in indoor model tests on piles with constant thickness-diameter ratio. The bearing capacity of long piles, short piles and the soil between piles cannot be fully mobilized at the same time. Besides, the bearing capacity of short piles is mobilized more than that of long piles. By analyzing the test results of the constant thickness-diameter ratio, the design of long-short rigid pile composite foundation with varying thickness-diameter ratios is investigated. It is believed that the varying thickness-diatmeter ratio, reduction of thickness-diameter of long piles and increase of thickness-diameter of short piles are suitable for the long-short rigid pile composite foundation. The varying thickness-diameter ratios can be realized by constant cushion thickness and varying pile diameters, in which the diameter of long piles is bigger. Otherwise it can be realized by constant pile diameter and varying cushion thicknesses, in which the thinner cushion of long piles is selected.