Recently,with the increasing development of domestic drilling technology ,more and more φ50 drill stem which is thicker than the standard 42 mm diameter has been found in SPT .In this article we take one construction in Shi-jiazhuang as an example and statistically analyses the relationship between SPT hit -numbers under the same sand layer and drill stem diameter .The result shows that there exists a significant correlation between SPT hit -numbers and drill stem diameter.If we don't use the standard drill stem which is φ=42mm for drill stem diameter,the SPT hit-numbers should be properly corrected .%近年来，随着国内钻探技术的不断提高，比规范规定直径42 mm更粗的φ50型钻杆越来越多的出现在标准贯入试验中（ SPT），本文以石家庄某工程为例，统计分析了SPT击数和钻杆杆径之间的关系。结果表明，标贯击数大小与钻杆杆径之间存在着显著的相关关系，若试验使用的钻杆不是标准的φ42钻杆，则标贯击数宜进行修正。
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