层状岩质边坡遍布节理模型的三维稳定性分析

Three-dimensional stability analysis of stratified rock slope based on ubiquitous-joint model

采用遍布节理模型(ubiquitous-joint模型)描述层状岩体的各向异性特征,并探讨ubiquitous-joint准则中安全系数的计算方法,利用FLAC3D分析层理倾角、倾向与边坡稳定性之间的关系,结果表明:(1)对于顺层边坡,当岩层倾向与坡面倾向的夹角α较小时,边坡的安全系数随层理倾角β的增大呈现先减小后增大再减小的趋势;β=20°～30°时,安全系数得到最小值,β=60°时安全系数得到最大值;不同破坏型式导致安全系数变化规律之间的差异;当α较大时,曲线从先减小后增大的趋势转变为不断增大的趋势;根据α的大小将顺层边坡分为两类:当α≤45°时,为严格顺层边坡;当45°<α<90°时,为斜向层状边坡。(2)对于逆层边坡,当α≤45°时,曲线呈现先增大再减小然后又增大的趋势,各曲线随β的变化程度基本相同;但减小过程中,随着α的增大,曲线的斜率逐渐减小,边坡稳定性的各向异性程度减小;当α>45°时,曲线随β的增大呈现非线性单调递增的趋势。(3)安全系数与α之间的关系表明,对于顺层坡,随着α的增大,边坡安全系数逐渐增大;对于逆层坡,当β较小时(β=150°),边坡安全系数随α的增大而逐渐减小;随着β的增大(β=120°),边坡安全系数与α呈现递增关系。

The anisotropic characteristics of stratified rock mass are described by ubiquitous-joint model; the calculation method of safety factor based on ubiquitous-joint model is proposed; then the relationships between stratification dip angle r, inclination and slope stability are analyzed by FLAC3D. The results show that （1） for bedding rock slope, when the angle α between inclination of slope and rock stratum is small, the slope safety factor decreases, increases and then decreases with the increase of β ; when β = 20-30° , the safety factor reaches the minimum value; while β = 60° , it reaches maximum value; different failure modes cause the variations of safety factor; when α is large, the relationship curve shows the decrease then increase trend to gradually increase; according to the value of α, the stratified rock slope can be divided into two types： α ≤ 45° for strict bedding rock slope; 45 ° 〈 α 〈 90 ° for oblique stratified slope; （2） for reverse layered slope, when α ≤ 45° , the relationship curve shows the trend of increase, decrease and then increase; the variation degree of each curve is almost the same with the variations of β ; during decrease process, the slope of curve decreases gradually with the increase of α, and the anisotropic characteristics of slope safety factor become small; when α 〉 45° , the relationship curve shows the trend of monotone increasing in nonlinear form; （3） the relationship between slope safety factor and α shows that for bedding rock slope, the safety factor increases with the increase of α ; for reverse layered slope, when fl is small （ β = 150 ° ）, the slope safety factor decreases with the increase of α ; and with the increase of β （ β = 120 °）, the slope safety factor increases while α increases.