贯入试验中锥因子的取值研究

Cone Factor Determinations in Penetration Test

落锥试验在许多地区广泛用于确定液限。影响锥体贯入过程的因素有锥体角度、锥体表面粗糙度、锥体周围土体的隆起以及土体的应变率效应。落锥试验作为确定细粒土液限的可靠方法,根据锥因子K可以确定土体的不排水抗剪强度。通过对K的理论值和实验值的研究,结合准静态和动态贯入的概念,分析了锥体进入土体的机理。利用解析方法,给出了动态不排水抗剪强度的表达式,并考虑了锥体表面粗糙度、剪切应变率和土体隆起,从而可以获得锥因子K的理论表达式。通过对比发现,30°的圆锥的锥因子值K离散度较大,建议使用60°锥体比30°的锥更适合确定液限。

As a reliable method to determine the liquid limit of finegrained soils,the falling cone test is widely used in soil laboratory testing.At the same time,the undrained shear strength of the soil can be determined from the cone factor K.By studying the theoretical and experimental values of K,combined with concepts of quasi-static and dynamic infiltration,the mechanism of the cone entering into the soil sample is analyzed in this paper.By using the analytical method,the expression of the dynamic undrained shear strength is proposed,and the cone surface roughness,the shear strain rate and the soil heave are considered,so the theoretical expression of the cone factor K can be obtained.Throughout the comparison,it is found that the cone factor K of a 30°cone has a large dispersion.Finally,based on the theoretical analysis results,it is suggested that the 60°cone is more suitable for determining the liquid limit than the 30°cone.