香港充填土风化花岗岩场址勘探中的界面识别研究

Identification of interface of earth fill with weathered granite in site investigation of Hong Kong

摘要: 针对香港充填土风化花岗岩场址勘探,在液压旋转钻机上安装钻孔过程监测系统(DPM),对有效轴压力、钻具转速、冲洗压力、钻头位移及穿孔速率进行了实时监测。采用变斜率作为显著性指数,对地层中的主、次界面进行了识别。t-检验表明:DPM系统对岩土界面识别的置信度为99%。此外,对穿孔参数在界面处的变化分析表明:这些参数随孔深的变化曲线在界面处存在不同涨落,轴压力和穿孔速率对界面上岩石强度变化的响应度为81.82%。

Abstract: A hydraulic rotary drillrig instrumented with a drilling process monitoring system(DPM) was used in site investigation of Hong Kong.The penetrating parameters such as effective thrust force,rotational speed,flushing pressure,penetrating rate and displacement of the bit were monitored in real time.A varying slope was defined as a significant index for identification of dominative and subsidiary interfaces in the granite site.It was shown by the result of t-test that the confidence of the DPM in identification of the geotechnical interfaces was 99%.Besides,the analysis of variation of the penetrating parameters on the interfaces indicated that there were different fluctuations on the interfaces in the variation of the parameters with borehole depth.The response degree of the effective thrust force and the penetrating rate to variation of rock strength at the interfaces was 81.82%.