顺层或逆层岩质急倾斜边坡坡角的确定

为了解当岩体具有急倾斜构造和水平裂隙发育时,由该岩体形成顺层和逆层边坡情况下,不同坡角对该边坡稳定性的影响,使用基于颗粒流理论的PFC3D进行了模拟。利用PFC3D中的JSET和Bonds模拟了非连续性和连续性的岩体构造形式。构建了坡角为40°、50°、60°、70°和80°的顺层和逆层边坡,并对边坡稳定性进行了模拟。模拟结果表明,岩层的重力作用在逆层时有利于岩体外倾,顺层时抑制外倾。相同坡角时顺层较逆层更为稳定。大变形裂隙区的出现位置与岩体构造有很大关系。提出的修建边坡坡角建议为顺层时坡角不应大于60°,逆层时坡角不应大于50°。

On the way for determining the slanting dip of the steep rock slope with bedding or inverse layers

The paper attempts to make an exploration of the way for determining the slanting dip grade of the bedding or inverse steep rock slope.In order to understand the effects of the different slope dips on the slope stability,we have made simulated slopes based on the PFC3D in accordance with the particle flow theory.In general,slopes are formed by the bedding or inverse layers in the steep inclined seams or horizontally fiat fracture in the slope.And,therefore,in correspondence with the above said structural features,we have made simulated structures of the discontinuous and continuous rock mass with the JSET or bonds in PFC3D.Whereas the steep structure dip in the rock is roughly about 87° degrees,the destructive characteristic features of the bedding and inverse layers tend to be weak.In order to test the fragile characteristic features of the bedding and inverse layers,we have simulated the constructive features of the slope in the dip forms in 40°,50°,60°,70° and/or 80° degrees,whose stability tend to be rather weak.The slope dip in an angle range between 40°-80° should thus have little effect on the dip of the dotted line under the inverse layer.Nevertheless,the underlying reason for the rock migration lies in the transition from the stress release to gravity.And,theoretically speaking,the fracture development regularity of the slope (the slope dip of 40°-80°) evolution with bedding can be the same with that of the inverse layer,though the migration of the slope rock tends to be more obvious in its development with different degrees on the condition with its changing limit no more than 70°.Thus,the comprehensive results of the simulation show that the effect of the rock gravity should help the rock decumbent in the inverse layer whereas it inhabits the decumbent process in the bedding layer.With the same slope dip,the bedding layer proves to be more stable than the inverse.What is more,the large deformed fractured zone should have been very much closely related with the rock mass structure condition.Thus,it can be seen that in the given formation conditions we are discussing here in this paper,the slope dip we have made clear should not be beyond 60° for the bedding layer while for the inverse layer,the slope dip should not be beyond 50°.