三维软硬互层边坡的破坏模式与稳定性研究

Numerical analysis of the failure modes and stability of 3D slopes with interbreeding of soft and hard rocks

采用FLAC^(3D)强度折减法,研究在岩层倾角、岩层与边坡走向夹角变化时三维软硬互层边坡的稳定性状况,并对其破坏模式进行辨识与归纳分析.结果表明:边坡破坏模式的判别应综合考虑岩层的倾角大小、岩层走向与边坡走向的夹角大小及坡面上的剪出条件;当岩层与边坡走向夹角β<90°时,随着岩层倾角α的增大,边坡的破坏模式变化趋势为由蠕滑-压致拉裂、塑流-拉裂、滑移-拉裂向滑移-弯曲、弯曲-拉裂转变;当β>90°时,边坡的破坏模式趋势为塑流-拉裂、滑移-弯曲、弯曲-拉裂;边坡稳定性系数随走向夹角的增大先增加后减小,β=90°时最大,且α越大,稳定性系数峰值越大;顺向时随着岩层倾角的增大,边坡的破坏模式变化趋势为蠕滑-压致拉裂、滑移-拉裂、滑移-弯曲、弯曲-拉裂,稳定性系数变化先减小后增大,存在一最不利岩层倾角,其对应的稳定性系数最小;反向坡的破坏模式变化趋势为蠕滑-压致拉裂和弯曲-拉裂,稳定性系数逐渐增加.

FLAG^3D strength reduction method had been adopted to research on the stability of 3D slopes with interbedding of soft and hard rocks, when the dip angle of stratum and the angle between the strike direction of slope and stratum changed, and the failure modes were identified and analyzed. The results show that ： to identify the failure modes of slopes, the angle of the rock stratum, the angle between the strike direction of slope and stratum and the cut off condition on the slope surface should be considered. Whenβ （the intersecting angle between the strike direction of slope and that of strata） 〈 90°, with the increase of α （the strata inclination）, the failure modes change from creeping-pressure induced ripping, plastic flowing-ripping, sliding-ripping to sliding-bending and bending-ripping; when β〉 90°, the failure modes change from plastic flowing-ripping to sliding-bending, and then become bending- ripping. With the increase of the angle between the strike direction of slope and stratum, the slope stability coefficient increases at first and then decreases, it reaches the maximum when β = 90°, and the greater the a is, the greater the coefficient peak is. For the dip slope, with the increase of the angle of stratum, the trend of failure modes is ： creeping- pressure induced ripping, sliding- ripping, sliding-bending, and bending-ripping. The stability coefficient decreases first and then increases, and there is a most unfavorable an- gle of the stratum, the corresponding stability coefficient is the least. As for the anti-dip slope, the trend of failure modes is creeping- pressure induced ripping and bending-ripping, and the stability coefficient increases gradually.