间隔时间对砂石桩动力触探检验结果的影响

Influence of Time on Dynamic Penetration Tests Used to Evaluate Ground Improved by Sand-Gravel Columns

砂石桩施工完成后须有一定间隔时间才能进行质量检验,但时间长短对检验结果影响的相关研究尚未见文献报道。现以某公园堆山软土地基的砂石桩为研究对象,采用0～39d不等的时间间隔对长度为8m和22m的砂石桩进行多次动力触探反复检验,以研究间隔时间对检验结果的影响。结果表明,动力触探是检测砂石桩密实度和长度的简单有效方法;砂石桩施工完成后,不宜立即开展动力触探检测工作;砂石桩施工约8d后,各深度砂石桩检测的动探击数趋于稳定,是进行动力触探检测的适宜时间。

In current ground improvement practice, a certain period of time is required after ground improvement by compacted sand- gravel columns before the iwsitu quality assurance testing can be performed. However, the quantitative influence of time on the QA test results within the columns has not been reported. The influence of time on the QA results is evaluated through a case study of soft ground improved by compacted san＆gravel columns for man-made hills of a theme park. Dynamic Penetration Tests （DPT） were per- formed on two san＆gravel columns with lengths of 8 m and 22 m. The tests were performed at different times after construction of the sand gravel columns ranging between 0 and 39 days. The testing results indicate that the DPT test is a simple and effective testing method for quality control of the density and the length of compacted sand-gravel columns. The blow counts in the columns are consist- ent at least 8 days after the completion of sand-gravel columns. It is recommended that the DPT should be performed 8 days after the column completion.