ND-CPT测量非均质地层密度剖面的研究

Study of density profile of heterogeneous strata measured by ND-CPT

同位素密度静力触探仪(ND-CPT)是一种把同位素密度仪并入到静力触探仪的探头中,同时测量锥尖阻力、侧壁摩阻力、孔隙水压力和密度的新型原位测试仪器。根据ND-CPT测量的密度为?射线源和检测器之间回转椭球体内土体的平均密度c?的原理,首先建立了可以计算回转椭球体内土体的平均密度c?的后向散射模型和平均值模型,然后调查了ND-CPT贯入各种非均质地层时的测量密度c?剖面与实际密度?剖面的区别,结果表明在地层分界处附近的测量密度c?与实际密度?有较大差别,最后对ND-CPT在实际工程中测量的有明海底泥的测量密度c?剖面进行了理解,得到了海底泥的实际密度?剖面。研究结果可为利用ND-CPT准确划分地层提供依据。

Nuclear density cone penetrometer(ND-CPT), incorporating the nuclear density probe into the probe of piezocone penetrometer, is a newly developed in-situ testing device that can simultaneously measure cone resistance, sleeve friction, pore water pressure and density. According to the principle that ND-CPT measures the average wet densityc? of the soil within a spheroid volume around the central point of the source and the detector, the backscatter and average value models which can calculate the average densityc? of soil within a spheroid volume are firstly proposed. Then, assuming ND-CPT is penetrated into various heterogeneous strata, the differences between the average densityc? profiles and the actual density ? profiles are investigated; and the results show that the measuredc? values are considerably different from the actual ? values near the boundaries of strata. Finally, the measuredc? profiles of seabed sediments in Ariake Sea, Japan, are interpreted and the actual ? profiles are deduced. The research results can provide the basis for accurate soil classification using ND-CPT.