京珠高速许漯段路基干拌水泥碎石桩加固研究

Testing on dry mixed cement gravel pile in embankment of Xuchang-Luohe Section of Beijing-Zhuhai Expessway

干拌水泥碎石桩是一项施工快速、不开挖路基的新型加固技术。针对京珠高速公路许漯段出现大量路基病害,采用此桩型进行加固处理。试验桩长为5.0 m,成孔直径为150 mm,间距为1.0 m×1.0 m,每层虚填料为25 cm,夯距为1.0 m,用120 kg重锤,分别对每层夯实10、8、7击的3根桩进行载荷试验,然后对每层夯实8、7击的2根桩进行重Ⅱ型动力触探试验。根据试验结果对比分析每层夯7击,单桩极限承载力达400 kPa,效果最优。通过地质雷达测试和室内土工试验对比分析加固前后路基土体变化,加固后路基不均匀变形减小,土体有效重度增加,含水率有所减少,桩体的吸水排水效果明显,桩的夯实挤密作用良好,路基的承载力和变形性能得到改善。经过桩加固后1年运行观测,加固后路段没有再次出现翻浆、叽泥等病害,表明此桩型加固高速公路路基效果显著。

Dry mixed cement gravel pile is a rapid, uncavated embankment new technology. It is applied on the embankment of Xuchang-Luohe Section of Beijing-Zhuhai Expressway. The length of the testing pile is 5.0 m, with 150 mm diameter, the interval between piles is 1.0 m×1.0 m; and height of filling mater is 25 cm; and it is tamped with 120 kg rammer, 31.0 m length of hammer ramming space. Three plate loading tests have been carried out with the pile of 10, 8, 7 pound per layer respectively; heavy duty dynamic sounding tests have been done with the pile of 8,7 pound per layer. The results show that the pile with 7 pound per layer of which the ultimate load capacity is 400 kPa is the best. Through geological radar and lab testing, valid unit weight added and water content reduced after construction. Embankment diseases have not been detected after they were treated one year, so it is shown that the pile is effective in treatment expressway embankment.