DataSheet1_Coseismic Stability Assessment of a Damaged Underground Ammunition Storage Chamber Through Ambient Vibration Recordings and Numerical Modelling.PDF

In the past decade, ambient vibration measurements found numerous applications on unstable rock slopes and developed into a powerful tool for site characterization of slope instabilities. In this study, for the first time ambient vibration measurements were applied to a rock mass strongly disturbed and damaged by subsurface explosions. The site above the ammunition storage chamber at Mitholz (Switzerland) is especially interesting because the subsurface geology below the seismic array is well known, including the location of the caverns, and the degree of degradation caused by the subsurface explosions in 1947 of around 40 t TNT of ammunition. Measurement data were analyzed using current state-of-the-art seismic single-station and array methods, focusing on surface-wave dispersion analysis, wave field polarization, wave amplification using site-to-reference spectral ratios and analysis of normal mode behavior. The results allow for calibrating the elastic properties of a 2D numerical rock mechanical model which was used to simulate the stability of the disturbed rock mass during seismic loading. Therefore, ambient vibration measurements can contribute not only to a better understanding of the subsurface, but also for the assessment of earthquake risk.

近十年来，环境振动测量在不稳定岩质边坡领域获得了大量应用，并已发展为边坡失稳现场表征的有力工具。本研究首次将环境振动测量应用于受地下爆破强烈扰动与损伤的岩体。位于瑞士米特霍尔茨（Mitholz）弹药储存洞室上方的研究场地极具研究价值，原因在于地震台阵下方的地下地质情况已被充分探明，包括洞室的位置，以及1947年约40吨TNT弹药地下爆破所造成的岩体劣化程度。研究采用当前主流的地震单台与台阵分析方法对测量数据进行处理，重点涵盖面波频散分析、波场偏振分析、基于台站-参考谱比法的波放大效应分析，以及简正振型特性分析。本次研究所得结果可用于校准二维数值岩体力学模型的弹性参数，该模型被用于模拟扰动岩体在地震荷载作用下的稳定性。因此，环境振动测量不仅有助于深化对地下地质情况的认知，还可用于地震风险评估。