地震作用下土质边坡渐进破坏特性及机理分析

There are large numbers of natural slopes distributed in our country, such as hills. With rapid development of the elementary constructions, numerous artificial slopes are appeared in the engineering, such as embankments and cuttings. Too many earthquakes have been happened in our country, which seriously destroyed these artificial earth slopes and induced a series of troubles. Based on the drawbacks in the researches of stability of slopes subjected to seismic excitation, a model test of seismic failures in earth slopes will be carried out. The effects of seismic excitation on the soil properties and the slip surfaces will be explored through model tests, dynamic triaxial tests and numerical simulations. The progressive failure mechanism and the shape of failure surface will be investigated on slope failures subjected to seismic excitation. A three-dimensional analysis of slope stability will be proposed by using the kinematic method of limit analysis. The dynamic strength values and criterions obtained by the dynamic triaxial tests will be used in the analysis of slope stability. The progressive failure mechanisms for sand or cohesive slope collapses will be interpreted in combination with the model test and numerical simulation. The results of this research have great academic contributions on the theory on the dynamic analysis of slope stability, which could be applied in the design and reinforcement.

我国丘陵、岗地分布广泛，这就从客观上决定了我国有大量的自然土质边坡；同时，我国大量的基础设施建设产生大量的人工土坡如公路路堑土坡。这些土质边坡通常由粘土、砂土或者粉土等堆积而成；抗震设防烈度7度及以上地区在我国广泛分布，土坡不可避免会遭受地震作用。本项目针对土坡地震稳定性研究存在的不足，开发土坡动力灾变模型试验技术，通过模型试验、动三轴试验和数值仿真，分析地震荷载对砂土或粘土强度特性及边坡滑动面的影响，揭示地震作用下砂土或粘土土坡渐进破坏模式、滑裂面开展过程和最终形状；采用极限分析法，提出土坡地震稳定性空间分析方法；最后根据研究得到稳定性分析方法、采用试验得到的动强度参数值和动强度准则，结合土坡动力灾变模型试验测量技术和数值仿真技术，揭示砂土或粘土土坡渐进破坏机理。研究成果具有重要的学术理论意义，进一步丰富边坡稳定性分析理论，且可应用于土坡抗震加固设计，从而减轻地震对土坡的破坏。

我国丘陵、岗地分布广泛，这就从客观上决定了我国有大量的自然土质边坡；同时，我国大量的基础设施建设产生大量的人工土坡如公路路堑土坡。这些土质边坡通常由粘土、砂土等堆积而成；抗震设防烈度 7 度及以上地区在我国广泛分布，土坡不可避免会遭受地震作用。本项目针对土坡地震稳定性研究存在的不足，以理论分析为主，结合实验研究，系统的开展了土质边坡地震动作用下动力稳定性研究。项目研究中的重要进展如下：（1）改进了三维边坡地震作用的转动破坏机制，揭示了边坡几何形状和土性参数对三维边坡最危险滑动面的影响机理，并给出了三维边坡稳定图表，便于工程中简单方便的估算安全系数；（2）基于边坡的滑动常以拉裂缝的出现为前兆这一客观事实，开展了存在裂缝情况下边坡稳定性研究，揭示了裂缝的特性对边坡安全系数的影响规律；（3）针对边坡加固中常用的两种加固方式（加筋加固和抗滑桩加固），分别开展了不同加固方式下边坡的地震稳定性研究，揭示了三维空间效应、加固体物理、力学特性对加固效果的影响规律。研究成果应用于山东临沂岸堤水库土石坝坝坡抗震及加固措施研究。在本项目资助下，共发表SCI论文13篇。