微震诱发边坡失稳的实验模型构建与稳定性评估

Experimental Model Construction and Stability Evaluation of Slope Instability Induced by Microearthquakes

摘要:

为揭示利咸高速公路两侧高边坡在地震作用下的位移响应机制及稳定性演化规律,采用模型试验与理论分析相结合的方法开展研究。聚焦于量化地震条件下高边坡位移特性,建立物理模型试验平台,模拟不同地震波参数(频率10~100 Hz、振幅0.05g~0.60g)下的边坡动力响应;结合有限元数值模拟进行理论验证,基于Mohr-Coulomb准则计算稳定性系数。严格遵循工程地质调查-模型构建-加载试验-数据采集-理论分析的技术路线,重点监测边坡顶部、断层带及中部区域位移。结果表明:边坡顶部因缺乏侧向约束,在地震波作用下水平位移呈现线性增长特征,振动次数超过2 000次后出现疲劳破坏迹象;断层带上缘对地震能量释放最为敏感,位移累积速率与振动次数呈指数相关。地震波频率对位移响应影响显著,低频段(≤40 Hz)的位移幅值较大但增速平缓,高频段(>40 Hz)易引发共振效应,导致位移突增15%~30%。稳定性系数分析显示,地震波振幅与所需振动次数呈对数函数关系。

Abstract:

To reveal the displacement response mechanism and stability evolution law of the high slopes on both sides of the Lixian Expressway under seismic action, a systematic investigation was conducted by combining model experiments with theoretical analysis. The focus was on quantifying the displacement characteristics of the high slopes under seismic conditions, and a physical model test platform was established to simulate the dynamic responses of the slopes under different seismic wave parameters (frequency ranging from 10 to 100 Hz, amplitude ranging from 0.05g to 0.60g). The finite element numerical simulation was combined for theoretical verification, and the stability coefficient was calculated using the Mohr-Coulomb criterion. The research process strictly followed the technical route of engineering geo-logical investigation-model construction-loading test-data collection-theoretical analysis, with a particu-lar emphasis on monitoring the displacement time history curves at the top, fault zone, and middle areas of the slopes. The research results show that the top of the slope, lacking lateral constraints, exhibits linear growth characteristics in horizontal displacement under the excitation of seismic waves, and signs of fatigue failure appear after more than 2 000 vibration cycles; the upper edge of the fault zone is the most sensitive to the release of seismic energy, and the displacement accumulation rate is exponentially related to the vibration cycle. The frequency of the seismic waves has a significant impact on the displacement response. The amplitude of the low-frequency band (≤40 Hz) has a larger displacement amplitude but a slower growth rate, while the high-frequency band (>40 Hz) is prone to resonance effects, causing a 15% to 30% increase in displacement. The stability coefficient analysis shows that the relationship between the seismic wave amplitude and the required vibration cycle is a logarithmic function.