考虑能量-时间分布的边坡动力可靠性分析新方法

A new method for reliability analysis of dynamic slope stability with considering energy-time distribution

提出一种考虑能量-时间分布的边坡动力可靠性分析方法。该方法将动态最危险滑动面及其稳定系数以时间序列加以刻画,并根据边坡动力反应的能量分布特征,提取持续时间统计窗,用于对上述时间序列的统计分析,以获取边坡动力模糊失效概率、边坡动力可靠度指标和基于保证率的边坡动力稳定系数。以澳大利亚计算机应用协会边坡稳定考核题为例,应用上述新方法考察其在芦山7.0级主震波形条件下的稳定性,研究了在不同统计窗下的边坡动力可靠性。案例分析表明:(1)新方法能够抓住影响边坡动力稳定的主要时间段,使分析结果更为凝练、可信。(2)通过引入边坡失效状态的模糊判别,使得可靠性评价中能够考虑模糊性,解决了以往常规方法区分度不够的问题。(3)基于保证率的边坡动力稳定系数具有很好的应用前景,它在内涵上体现了可靠性分析,在形式上与静力稳定系数的定义兼容,在数值上反映了边坡瞬时动力稳定系数的保守估计值,在实践上与现行规范的拟静力法具有良好的可比性,因而具有多方面的优势。(4)就本案例而言,动力条件下最危险滑动面的发育位置趋向于静力条件下的最危险滑动面,体现了依据静力和拟静力理论框架所进行的防护工程设计,在动力条件下仍然具有积极的意义。(5)新方法对定量研究现行边坡规范的抗震设计冗余提供了一条途径。提出的新方法为边坡抗震研究提供了新的思路、方法和可供参考的实例。

A new method for dynamic reliability analysis of slope stability is proposed with considering the energy-time distribution. In this method, the dynamic critical slip surfaces and their factors of safety （FOS） are described as time series. The slope reliability evaluation criteria including dynamic fuzzy failure probability, dynamic reliability index and dynamic FOS, are obtained utilizing the statistical windows of duration that are extracted according to the characteristics of energy distribution of slope dynamic response. To validate the proposed method, a soil slope stability standard testing problem issued by Australian Association for Computer Aided Design （ACADS） is analyzed under the conditions of the Lushan Ms =7.0 earthquake. The differences of analysis results, which are controlled by the selection of statistical windows of duration, are studied in detail. The case study shows that： （ 1 ） The new method can yield good results by emphasizing the most significant time period. （2） The fuzzy discrimination for slope failure state significantly improves the reliability evaluation, which avoids the problem of insufficient discrimination of the traditional methods. （3） The guaranteed-probability-based dynamic FOS of slope has great potential of application and inherent the advantages for reliability analysis. Formally it is compatible with the definition of static stability FOS; quantitatively it is the conservative estimate of instantaneous FOS; and practically it compares well with the pseudo-static method in existing design specifications. （4）In this case, the locations of dynamic critical slip surfaces tend to approach the static critical slip surface. It is illustrated that a reinforcement design under a static or pseudo-static method framework still has a positive meaning in dynamic seismic conditions. （5） The new method provides a way to quantitatively determine the optimal redundancy of seismic design specifications. In summary, the new method provides new ideas, techniques and a reference example for slope seismic analysis.