长短桩复合地基荷载分担比的试验研究

为了研究长短桩复合地基竖向荷载分担比的变化规律,在室内模型试验的基础上,对不同桩间距、垫层厚度、长桩长度、短桩长度、长桩模量和短桩模量等情况下长短桩复合地基荷载分担比的变化性状进行了分析。结果表明,随桩间距的减小,长桩和短桩的荷载分担比均增大,桩间土的荷载分担比减小,通过减小桩间距来提高长桩荷载分担比是不经济的;随垫层厚度的增加,长桩的荷载分担比减小,桩间土的荷载分担比增大,短桩的荷载分担比变化较小,垫层的设置能明显改善桩、土荷载分担的分配;随长桩长度的增加,长桩的荷载分担比增大,桩间土的荷载分担比减小,短桩的荷载分担比变化较小,增加长桩长度能一定程度提高长桩荷载分担比;短桩长度对荷载分担比的影响较小;随长桩模量的增大,长桩的荷载分担比增大,桩间土的荷载分担比减小,短桩的荷载分担比变化较小,增加长桩模量能显著提高长桩荷载分担比;随短桩模量的增大,长桩的荷载分担比减小,短桩和桩间土荷载分担比均增大,增加短桩模量对荷载分担比分配有一定影响。

Model Test Study on Load Sharing Ratio of Composite Foundation with Long-short Piles

In order to study the change law of load sharing ratio of composite foundation with long-short piles,the behavior of load sharing ratio was studied on the basis of laboratory tests,in which the pile spacing,cushion thickness,long pile length,short pile length,long pile modulus and short pile modulus were taken into account.Conclusions are as follows:With the decreme nt of pile spacing,the load sharing ratio of long and short piles became larger while that of soil became smaller.It was not economical by reducing the pile sp acing to improve the load sharing ratio of long pile;With increasing thickness of cush ion,the load sharing ratio of long piles became smaller,the load sh aring ratio of soil became larger while that of short piles changed little.Sett ing a cushion significantly improved the pile and soil load-sharing allocatio n;With increasing length of long piles,the load sharing ratio of long pile s became larger,the load sharing ratio of soil became smaller while that of sho rt piles changed little.Increasing long pile length improved,to some extent,the long pile load sharing ratio;Short piles length had little effect on load sharing ratio;With increasing long pile modulus,the load sharing ratio of long piles became larger,the load sharing ratio of soil became smaller while th at of short piles changed little.Increasing the length of long pile modulus significantly improved the long pile load sharing ratio;With increasing short pile modulus,the load sharing ratio of long piles became smaller while that of short piles and soil became larger.Increasing short-pile modulus had a certa in influence on load sharing ratio distribution.