砂土地基冲击碾压加固效果影响因素的试验研究

冲击碾压技术已在国内外公路工程、机场工程以及港口工程等不同行业得到广泛应用，但有关冲击碾压加固效果的影响因素及影响规律尚不明确。文章利用自行研制的冲击碾压模拟试验设备，通过室内模型试验手段，分析冲击轮重量、冲击轮形状、牵引速度、土体的初始密实状态及冲击碾压遍数等因素对砂土地基冲击碾压加固效果的影响。试验结果表明:冲击轮重量对砂土地基冲击碾压加固效果的影响起主要作用，冲击轮单轮质量大于10 t时冲击碾压加固砂土地基的影响深度明显增加，2.4~3.6 m深度范围的加固效果最明显；初始状态为松散至中密的砂土对应的冲击碾压加固效果较好；三边形冲击轮的冲击碾压加固效果明显优于四边形和五边形冲击轮；牵引速度在12 km/h范围内时，砂土地基的冲击碾压加固效果随牵引速度的增加而增长，但牵引速度为9 km/h时，浅表层1.4 m深度范围的加固效果较好；同时在12遍冲碾过程中，浅层2.4 m深度范围的加固效果随着冲碾遍数的增加而有较明显增长。研究成果可为冲击碾压法加固浅层砂土地基的设计与施工提供参考。

Laboratory investigation on influencing factors of improvement effect of rolling dynamic compaction on sand

As an efficient and cost -effective shallow ground improvement technology, rolling dynamic compaction (RDC) has been widely used in various industries such as highway engineering, airport engineering and port engineering at home and abroad, but the influencing factors and rules of improvement effect of the RDC are still seldom examined. By using a self -developed RDC simulation test equipment, a laboratory investigation on influences of factors such as weight of impact module, shape of impact module, working speed, initial dense state of soil and passes of RDC on the improvement effect of RDC for sand are carried out. The results show that (1) the mass of impact module has major influence on the improvement effect of RDC for sand, and while the weight of impact module is greater than 10 t, the influencing depth of RDC increases obviously and the most significant improvement is within the depth of 2.4~3.6 m. (2) The sands with the initial loose and medium -dense state have better improvement effect of RDC. (3) The improvement effect of triangular impact module is better than the quadrilateral and pentagonal impact modules. (4) While the working speed is less than 12 km/h, the improvement effect of RDC for sand increases with the increasing of working speed, but the speed needs to be decreased to be 9 km/h to achieve better improvement of the superficial zone of ground (around 1.4 m deep).(5) The improvement effect also increases with the increasing pass of RDC during 12 passes compaction. The research results can provide reference for the design and construction of improvement of RDC for sand.