- 學位論文
岩楔穩定與振動特性關係探討
Relationship between Rock Wedge Stability and Vibration Characteristics
摘要
由於台灣特殊的地質與氣候條件，近年來多次發生坡面岩塊崩落的意外事件，使用路人及車輛必須承擔很大的風險，並在道路的維護上產生極大的隱憂。岩楔是由不連續面所構成，傳統的調查方法通常由地質學家及工程學家親臨現場進行調查，藉由露頭調查直接接觸當地的地質材料，配合不連續面特性的分析與岩體工程特性等等關鍵因素，提供其穩定性的建議。國際岩石力學學會(International Society for Rock Mechanics, ISRM)針對不連續面的調查給予描述項目的相關建議，使各類岩體評估分類方法與應用廣泛使用在工程界。然而此類的方法較少描述到力學行為特性，較無法滿足運動學以及岩體變形分析所需使用之參數。 本研究主要針對數種不同的岩楔失穩狀態，建立其數學模型與物理模型，利用不同的坡面坡度與粗糙度產生不同的穩定性，以拉力試驗計算該坡面摩擦係數，並利用極限平衡法計算其安全係數，以簡諧激振的加入量測危險岩楔振動訊號，通過訊號分析自然頻率的變化，討論影響岩楔振動訊號變化之關鍵因素，將訊號特徵作為判別岩楔穩定度之指標，以提供邊坡監測和相關技術開發。 研究結果顯示，透過量測坡體岩塊與岩楔的振動特性，可以證明物理模型具有模擬現地微振動狀況，利用數值分析方法加以佐證。將岩楔穩定性區分成三個階段。可以發現在岩楔極為穩定的情況(第一階段)，容易判別主頻率，並且在低頻率與主頻率振幅高，而高頻率振幅與主頻率振幅比值低；隨著安全係數下降(第二階段)，低頻率與主頻率的振幅降低至趨近於零，而高頻率振幅與主頻率振幅比值升高；當岩楔到達臨界情況時(第三階段)，低頻率與主頻率振幅會有小幅上升的情形，而高頻率振幅與主頻率振幅比值將會降低。
並列摘要
Due to the geological conditions and climate change, Taiwan has repeatedly reported incidents of rockfall on slopes in recent years, endangering the safety of pedestrians and causing great concerns in road maintenance. Rock wedges are composed of discontinuities and slopes. Traditional survey methods usually involve geologists or engineers who come in direct contact with the geotechnical materials at the site, using the most direct and reliable outcrop survey method. However, it rarely involves physical characteristics. The parameters required for kinematic analysis and deformation analysis cannot be met. This study intends to establish mathematical models and physical models for several states in which wedge instability may occur. Use different slope angle and roughness to create different stability, and get the safety factor of each slope through the tensile test on the slope, obtain the change of natural frequency through signal analysis then discuss the influencing factors of rock wedge vibration to provide a reference for slope monitoring and related technology development. The research results show that by measuring the vibration characteristics of the rock blocks, it can be proved that the physical model can simulate the microtremor conditions on-site, which can be supported by numerical analysis methods. the stability of the wedge is divided into three stages. It can be found that when the rock wedge is extremely stable (the first stage), it is easy to distinguish the predominant frequency, and the amplitude of the low-frequency and the predominant frequency is high, and the ratio of the high-frequency amplitude to the predominant frequency amplitude is low; as the safety factor decreases (the second stage), the amplitude of the low-frequency and the predominant frequency decreases to approach zero, while the ratio of the high-frequency amplitude to the predominant frequency amplitude increases; when the rock wedge reaches the critical state (the third stage), the amplitude of the low-frequency and the predominant frequency will have a small increase, the ratio of the high-frequency amplitude to the predominant frequency amplitude will decrease.
參考文獻
延伸閱讀
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