地工泡棉加勁土壤受爆炸荷載之數值分析

Abstract

地表爆炸所產生之壓力波會對地下結構物之安全造成威脅，本研究進行一系列數值模擬以探討地工泡棉加勁土壤於爆炸荷載下之動態行為與爆震波衰減機制。本研究之數值模型可分為未加勁砂土及地工泡棉加勁砂土兩種模型，模型中以150公斤TNT炸藥於土層表面引爆，並於炸藥引爆點距地表3公尺處之土層量測模型估計之土壤壓力及垂直加速度值。比較加入地工泡棉前後之土壤壓力與垂直加速度值，可發現土壤中之尖峰爆壓值衰減60.77%、最大垂直加速度衰減83.24%。本研究經過參數敏感性研究確認地工泡棉之爆壓衰減機制主要依賴地工泡棉與周圍土壤之波阻抗差。此外，本研究針對地工泡棉之建構方法(泡棉種類、泡棉厚度與泡棉埋設深度)進行了參數研究以探討地工泡棉加勁土壤於尖峰爆壓衰減性能最佳化之設計。參數研究結果顯示，隨地工泡棉密度增加、泡棉厚度與埋設深度提升時，土壤中之尖峰爆壓將有顯著衰減，尖峰爆壓之衰減最大可達80.09%，最大垂直加速度衰減則可達到96.97%。本研究基於數值模擬研究成果，提供了地工泡棉加勁土壤受爆炸載重時之量化分析流程與設計建議，可做為未來地下結構物進行防爆性能提升或設計時之參考選項之一。

Pressure waves generated by surface explosions pose a significant threat to the safety of underground structures. This research conducted a series of numerical simulations to investigate the dynamic behavior of geofoam-reinforced soil under blast loads and the blast attenuation mechanism of geofoam-reinforced soil. The numerical models in this research are divided into two types: unreinforced and reinforced. In both models, 150 kg of TNT explosives are detonated on the surface of the soil layer. The blast pressure and vertical acceleration are measured 3 m below the ground surface at the point of detonation. The results show that, with geofoam reinforcement, the peak blast pressure is reduced by 60.77%, and the peak vertical acceleration is reduced by 83.24%. This confirms that the blast attenuation mechanism of geofoam-reinforced soil is based on the difference in wave impedance between soil and geofoam. Additionally, parametric studies were conducted to investigate the effects of various geofoam parameters (type, thickness, and embedded depth) on blast attenuation. The results indicate that as the density, thickness, and embedded depth of the geofoam increase, the protection effectiveness also increases. Specifically, the study found an 80.09% reduction in peak blast pressure and a 96.97% reduction in peak vertical acceleration within the scope of this research. Based on the numerical results, this research provides a quantified research procedure and design recommendations for geofoam-reinforced soil subjected to blast loads, offering valuable guidance for the future design of blast-resistant underground structures.