标准贯入试验测量击打能量的试验研究

Experimental Study on Measurements Hitting Energy with Standard Penetration Test

标准贯入试验是最常用的勘察手段之一,具有历史悠久、操作简单、造价低廉、可参考和借鉴的经验丰富等优点。但传统的数标贯击数的方式缺乏理论支持,且试验过程中存在因设备差异和杆长不同带来的标准贯入击数的误差问题,通常的做法是采用测量击打能量来对锤击击数进行修正。本文在前人研究的基础上,开展标准贯入试验的击打能量测量的试验研究。具体的方法是通过实时采集钻杆在受自由落锤锤击时的加速度信号,并对高频波干扰进行低通滤波,并采用力量速度法将加速度物理量转化计算,实现在标准贯入试验过程中实时监测击打能量。通过在不同密度的砂土中采用此法进行试验,得到不同密实度相对应的击打能量呈规律性的不同的结论。国内在标准贯入试验的定量化与自动化方面的研究还较少,本文的研究对推动国内在此领域的进展有一定积极的意义。

Standard Penetration Test （SPT） is one of in-situ tests which are extensively used in geotechnical engineering area. It has a long history and have advantages such as intuition in measuring variable, easy for workers in operation and for engineers to understand, small in cost, and most importantly, have a huge accumulation of engineering data and corresponding empirical formulas. However, it is still lack of theoretical support, the differences of test equipments and length of drill pipe will bring error. The usual method to deal with this problem is measuring hitting energy to correct the blow count （SPT-N value）. This paper devote itself to carry out test research measuring hitting energy during standard penetration test, based on previous studies. The specific method in this paper is using data acquisition tools to obtain the real time acceleration signal, filtering the high frequency acceleration wave, then converted it to hitting energy by FV method. In this way, the hitting energy monitoring during standard penetration test could be completed. After using this modified method in varied sand site with different density, the result have been obtain that the hitting energy present obvious regularity which could reflect the strength of soil. The research of quantitative and automation of SPT was seldom in china, this paper is trying to promote progress in this area.