岩溶峰丛洼地铁路软土地基碎石桩施工技术研究

Research on the Construction Technology of Crushed Stone Pile for Soft Soil Railway Foundation in Clustered Depression At Yanrongfeng

研究目的:结合洛湛铁路洪塘至岑溪段贺州车站软土地基碎石桩施工,对岩溶峰丛洼地铁路软土地基碎石桩施工技术进行了试验研究。研究结论:岩溶峰丛洼地铁路软土地基碎石桩,考虑软弱土层夹碎、块石,且基底石灰岩溶沟、溶槽发育,采用沉管法施工遇溶沟、溶槽陡倾斜面或较大粒径孤石时,可能出现成桩困难,经比较,选用适应性较强的振冲法进行施工。岩溶峰丛洼地软弱土层基底石灰岩溶沟、溶槽发育,施工中碎石桩桩长出现异常情况时,应结合相邻桩长进行分析,必须排除振冲头遇土土层中孤石而造成桩长异常的情况,确保碎石桩按设计要求打穿软土层;通过现场试验,提出了对桩长与相邻桩相比短于1 m需结合相邻桩进行分析的规定,以及对判断属于振冲头遇土层中孤石而造成桩长异常时采取补桩的措施。工程实践表明,所提出岩溶峰丛洼地铁路软土地基碎石桩施工机械设备选型、施工工艺、质量控制要点以及施工问题处理措施可行,可供类似工程参考。

Research purposes： Combining with the crushed stone pile for the soft soil foundation in the section between Hongtang and Cenxi of Luoyang - Zhanjiang Railway, the experimental research is done on the construction technology of crushed stone pile for the soft soil railway foundation in clustered depression at Yanrongfeng.Research conclusions： Adopting the crushed stone pile with pipe sinking method to reinforce the soft soil railway foundation in clustered depression at Yanrongfeng is probably difficult to form the pile when encountering the big steep and incline face of solution channel and fluid bowl or encountering the isolated stone of big grain size because of the developments of the solution channel and fluid bowl of lime rock in foundation base. After making comparison, the vibro - replacement stone column with perfect adptability is used. When the abnormal situation of the pile length of crushed stone pile due to the developments of the solution channel and fluid bowl of lime rock in soft foundation base in clustered depression at Yanrongfeng happens, the analysis should be made in combination with the pile length of adjacent pile so as to eliminate the abnormal situation caused by the isolated stone in soil bed faced by the vibro -replacement head for ensuring the crushed stone pile penetrating into the soft soil bed as required in design. Based on the field tests, the stipulation is offered that the analysis should made in combination with the pile length of the adjacent pile when the pile length is 1 m shorter than the adjacent pile, and the measure of supplying pile is also presented for the abnormal situation of pile length caused by the isolated stone in soil bed faced by the vibro - replacement head. The application shows the equipment selection, construction technology, key points of quality control of crushed stone pile for the soft railway foundation in clustered depression at Yanrongfeng and its treatment measures are feasible.