节理岩体体积节理数Jv的新计算公式

岩体体积节理数Jv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，Jv定义的适宜性，指出节理正交的情况下Jv的适宜性最好，推导出Jv的修正系数为K1=|sin(n1,n2DD(-1]HT5SS]^HT]]DD)])||cos(n1n2,n3DD(-1]HT5SS]^HT]]DD)])|，研究表明:节理夹角越小，对Jv的影响越大；通过连通率等效途径，断续节理岩体的Jv计算公式为Jv=K1DD(]]iDD)]Sini(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。

NEW FORMULAE FOR VOLUMETRIC JOINT COUNT Jv OF JOINTED ROCK MASS

The joint space or frequency are more suitable for the definition of volumetric joint count Jv in the Code of Engineering Rock Mass Classification. The suitability of Jv for rock mass with one, two or three sets of persistent joints is discussed. A correction factor K1 of Jv is calculated with the formula: K1=|sin(n1,n2DD(-1]HT5SS]^HT]]DD)])||cos(n1n2,n3DD(-1]HT5SS]^HT]]DD)])| . The influence of intersection angles between different joint sets on Jv is discussed. Then the definition of Jv for rock mass containing intermittent joints is deduced on the basis of joint persistence ratio with a new formula of Jv=K1DD(]]iDD)]Sini(i3). The degree of joints in rock mass could be expressed more objectively with the proposed formula.