超高黄土不稳定斜坡的防治设计及效果评价

Prevention and Control Design and Effectiveness Evaluation of Unstable Slopes on Ultra-high Loess

为有效保证超高黄土不稳定斜坡的稳定性,以上合院不稳定斜坡为工程背景,在边坡基本特征及稳定性分析基础上,开展其防治设计,再通过变形预测构建防治效果评价指标,并以其评价防治手段的效果。分析结果表明:结合边坡防治现状及基本特征,可将其防治现状划分为了三段,其中,Ⅱ分段未采取防治措施,且其对前缘建设场地具有直接威胁,并经稳定性评价,得出Ⅱ分段边坡在工况1(天然工况)条件下属基本稳定~稳定状态,但在工况2(暴雨工况)条件下属不稳定状态,并将安全系数设置为1.2时,得其最不利剩余下滑力为191.47 kN/m,因此,此段治理必要性显著。为切实保证不稳定斜坡的稳定,提出采用“桩板墙”进行防治,且在防治后进行变形监测及后续预测,得出边坡防治后的变形虽会进一步增加,但增加速率趋于减小,所得评价指标Xs的取值范围介于0.60~0.92,防治效果等级为Ⅱ级,即边坡后续变形具一般收敛趋势,其防治效果较优,能有效保证其稳定。

In order to effectively ensure the stability of unstable slopes on ultra-high loess,the unstable slopes of the above institute are taken as the engineering background.Based on the basic characteristics and stability analysis of the slopes,prevention and control design is carried out,and then deformation prediction is used to construct evaluation indicators for prevention and control effectiveness,and the effectiveness of prevention and control measures is evaluated.The analysis results show that the current prevention and control situation of the slope can be divided into three sections according to the current prevention and control situation and basic characteristics of the slope.Among them,the prevention and control measures are not taken in Section II,which poses a direct threat to the front edge construction site.Through stability evaluation,it is concluded that the slope of Section II is basically stable~stable under Condition 1(natural condition),but unstable under Condition 2(rainstorm condition),when the safety factor is set to 1.2,the most unfavorable remaining sliding force is 191.47 kN/m,therefore,the necessity of governance in this section is significant.In order to effectively ensure the stability of unstable slopes,it is proposed to use"sheet pile wall"for prevention and control,and conduct deformation monitoring and subsequent prediction after the prevention and control.It is concluded that the deformation of the slope after prevention and control will further increase,but the increase rate tends to decrease.The value range of the evaluation index Xs is 0.60~0.92,and the prevention and control effect is Grade II,that is,the subsequent deformation of the slope has a general convergence trend,and its prevention and control effect is better,which can effectively ensure its stability.