节理岩体体积节理数Jv的新计算公式

NEW FORMULAE FOR VOLUMETRIC JOINT COUNT J_v OF JOINTED ROCK MASS

岩体体积节理数Jv的定义,按照《工程岩体分级标准》采用节理间距或频率较为恰当;本文研究了岩体内发育一组、二组、三组贯通性节理的情况下,Jv定义的适宜性,指出节理正交的情况下Jv的适宜性最好,推导出Jv的修正系数为K1=|sin(n1,^n2)||cos(n1×n2,^n3)|,研究表明:节理夹角越小,对Jv的影响越大;通过连通率等效途径,断续节理岩体的Jv计算公式为Jv=K1.∑Si.ni(i 3)。运用该公式可实现工程岩体裂隙发育程度的科学评价。

The joint space or frequency are more suitable for the definition of volumetric joint count Jv in the Code of Engineering Rock Mass Classification. The suitability of Jv for rock mass with one, two or three sets of persistent joints is discussed. A correction factor K1 of Jv is calculated with the formula： K1=｜sin（n1, n2）｜｜cos（n1×n2,n3）｜. The influence of intersection angles between different joint sets on Jv is discussed. Then the definition of Jv for rock mass containing intermittent joints is deduced on the basis of joint persistence ratio with a new formula of Jv=K1·∑i Si·ni（i≤3）.The degree of joints in rock mass could be expressed more objectively with the proposed formula.