覆盖型岩溶土洞泡沫混凝土复合地基模型试验研究

Model test of Foam Concrete Composite Foundation in Karst Covered Area

通过建立室内模型,进行了复合地基变形特性研究试验,研究覆盖型岩溶土洞泡沫混凝土复合地基的变形特性。试验设置两种工况共九组试验,探讨在分级荷载作用下不同桩长形成的复合地基的沉降规律,处理前后的土压力变化规律,以及桩土荷载分担比的变化规律。结果表明,当溶洞无充填物时,利用泡沫混凝土进行充填及作竖向增强体桩,桩体与充填体形成整体,与桩间土共同形成复合地基,地基承载力提升明显。若桩长继续增加,承载力没有提高,桩体工作性状接近端承桩。当溶洞被其它软弱土层充填时,桩长越长,承载力越高,但达到一定长度之后承载力提升有限,桩体工作性状接近摩擦桩。试验结果对泡沫混凝土复合地基处理覆盖型岩溶土洞的应用具有参考价值。

The purpose of this paper was to investigate the deformation characteristics of the covered karst treated by foam concrete composite foundation.The deformation characteristics of the composite foundation were studied by establishing the indoor model.The test set two working conditions and nine tests of composite foundation formed by different pile lengths were done under the hierarchical loads.The settlement regularities,the change rules of soil pressure before and after treatment,and the stress of pile were discussed.The results demonstrated that the foam concrete pile and the foam concrete filling formed a unit without filling in the cave.The composite soil was formed together with the soil between the piles.The bearing capacity of the foundation was obviously improved.With increase in the pile length,the bearing capacity was not improved.The working characteristics of the pile were close to that of the end-bearing pile.When the karst cave was filled by soft soil,the foam concrete pile formed composite foundation with the soil between the piles.The longer the pile length was,the higher the bearing capacity was.However,after reaching a certain length,the bearing capacity reaches its limit.The working characteristics of the pile were close to that of the friction pile.The test results are of great reference value for the application of foamed concrete composite foundation to covered karst.