山区顺坡填筑边坡稳定的强度折减有限元分析

为分析山区顺坡填筑时,岩基坡度及填筑体与岩基界面粗糙度对边坡稳定性的影响,用强度折减有限元法,对完整基岩斜坡上顺坡填筑边坡的稳定性进行计算分析。给出了边坡安全系数、最危险滑移面及其与简化Bishop法计算结果的差异随岩基坡比及界面粗糙度的变化情况。结果表明:完整岩基上顺坡填筑边坡的失稳滑移面在有些情况下与圆弧差异较大,简化Bishop法给出的安全系数会有较大误差;当界面非完全粗糙时,随岩基坡度变大,则有原较强斜坡地基的"限制"作用和较弱界面的"弱化"作用使滑移面变化,前者使体系安全系数增大,而后者则相反;将强度折减有限元法应用到山区岩质斜坡地基上高填方的稳定性分析中,能避免按圆弧滑移面搜索所计算安全系数误差较大以及按复杂滑移面搜索的困难。强度折减限元法不仅简便且计算效率高,应用前景比极限平衡法更广阔。

APPLICATION OF FEM WITH STRENGTH REDUCTION TO STABILITY ANALYSIS OF FILLED SLOPE ON INCLINED ROCK GROUND

The strength reduction FEM was adopted to analyze slope stability influenced by the gradient of inclined rock ground as well as interface roughness between the fills and the ground.Safety factors,the most dangerous sliding surface as well as their difference from those calculated by the simplified Bishop method were presented.The results showed that for filled slope on inclined intact rock ground,the sliding surface was quite different from circular surface in some cases.There would be considerable error if safety factors were calculated by the simplified Bishop method.Furthermore,for filled slope on inclined intact rock ground with non-full rough interface,there were "restriction" mechanisms of the inclined rock ground with relatively high strength and "weaking" mechanisms of the interface,acting on the sliding surface.The former enhanced slope stability,while the latter acted the opposite.The calculation also showed that FEM with strength reduction,applied to the stability analysis of high filled slopes on mountainous ground,could give more realistic shape and position of the sliding surface and consequently more reliable results for the safety factor.In contrast,the conventional limit equilibrium analysis methods,with the usual assumption of circular sliding surface,might give poor results for this type of complicated problems.FEM with strength reduction was simple and efficient.Therefore,its application prospect was more extensive than limit equilibrium method.