基于动力触探的钙质土相对密实度研究

Study of relative compaction for calcareous sand soil using dynamic cone penetration test

圆锥动力触探试验(DCPT)是一种用来预测地基土相对密实度的方法。然而,现有的预测公式主要针对石英土。为解决这一问题,通过现场以及室内模型试验,得到了轻型动力触探贯入指标与钙质土相对密实度之间的关系。可知相比于石英土,粒径对钙质土贯入指标的影响较为显著。若采用现有公式计算钙质土的相对密实度,得到的数值偏大,结果偏于危险。为了便于工程应用,基于Butterfield改进的量纲分析理论,建立了一种可将不同形式DCPT的贯入指标进行相互转化的方法,实现了轻型与重型动力触探指标之间的相互转换,进而得到了重型动力触探贯入指标与钙质土相对密实度之间的关系。根据现场重型动力触探试验数据可知,上述关系的计算结果与现场实测结果吻合良好。

The dynamic cone penetration test(DCPT)has been widely used in predicting the relative compaction of the foundation soils.However,the current formulas might not be suitable for the calcareous sand soils.To address the problem,a series of in situ and model DCPT were conducted to obtain the relationship between the light dynamic penetration index and relative compaction for the calcareous sand soils.The results show that the effect of particle size on the penetration of calcareous sand is more significant than that of the quartz sand soils.Under the similar relative compaction,the penetration of calcareous sand soils is smaller than that of the quartz sand soils with similar gradation.For engineering applications,a method which could transform the penetration index between the different kinds of DCPT is proposed according to the improved Butterfield’s dimensional analysis theory.Then the light dynamic penetration index is transformed to the heavy dynamic penetration index using this method,so that a relationship between the heavy dynamic penetration index and relative compaction of the calcareous sand soils is obtained.Finally,the relationship was verified based on the results of the field heavy dynamic penetration test.