考虑随机横向节理的反倾层状边坡倾倒破坏分析

Analysis of toppling failure of anti-dip layered slope with random cross joints

实际边坡工程中,横向节理极其发育,且节理位置分布随机,节理长度也各不相同,随机横向节理对反倾向层状边坡倾倒破坏的影响规律尚不清楚。为此,通过计算机随机生成了横向节理的位置系数和长度系数来表征横向节理的随机特性,建立随机横向节理反倾向层状边坡模型。应用该模型探讨边坡发生倾倒破坏的启动条件和破坏机理,并基于极限平衡理论确定岩层的破坏模式和破坏位置。以皖南山区的典型反倾向层状板岩边坡为研究对象,分析横向节理位置和横向节理长度对边坡倾倒破坏的影响规律。结果表明:无论横向节理如何分布,岩层(从坡脚至坡顶)发生破坏所需的层间力总是先增大后减小;当横向节理位置或者横向节理长度发生改变时,潜在破坏岩层的层间力也随之发生改变,且其数值随横向节理长度的增加而明显减小;当横向节理位置和横向节理长度都随机改变时,层间作用力曲线形状变化较大,个别岩层发生破坏时所需的层间力差值较大。研究结论对反倾层状边坡倾倒破坏机理的认识与地质灾害防治有参考价值。

In actual engineering slopes,cross joints widely exist in rock strata and locate randomly,and their lengths vary from each other.The effect of cross joints on the toppling failure of anti-dip layered slope is not clear.Therefore,the joint position coefficient and length coefficient are randomly generated by computer to reflect the random properties of cross joints,and we establish an anti-dip layered slope model with random cross joints,and investigate the starting condition and failure mechanism of slope toppling deformation.The failure modes of rock strata and their corresponding failure positions are determined based on the limit equilibrium theory.Finally,taking a typical anti-dip layered slate slope in southern Anhui Province as an example,we discuss the influence of the locations and lengths of cross joints on toppling failure.The results show that the inter-layer forces of rock strata(from the toe to the top)required for shear failure or bending tension failure increase first and then decrease no matter how the cross joints are distributed.When the locations or lengths of the cross joints change,the inter-layer forces of potentially failed rock strata will also change,and it will decrease obviously with the increase of the lengths of the cross joints.When the locations and lengths of cross joints change randomly,the shape of inter-layer force curve will change greatly,and the difference of inter-layer forces when certain rock stratum is damaged will vary largely.The results can provide references for understanding the mechanism of toppling failure of anti-dip layered slopes and its geological disaster prevention.