| 摘要: | 本研究以離散元素法(Discrete Element Method, DEM)模擬苗栗縣南庄鄉鹿湖山區土石之崩塌行為，此次山崩事件排除地震與降雨兩大誘因，為乾顆粒的崩落。由中興工程顧問社提供的地形資料作為比對依據，經由驗證本研究離散元素模型的合理性後，並進一步研究顆粒體崩塌運動過程中的傳輸性質與內部物理性質，包括平移速度向量、擾動速度分佈、粒子溫度、配位數、粒子體積佔有率及von Mises應力。顆粒間摩擦係數較小時，碰撞機制主控能量損失，沉積情況相較於實際沉積形貌較為細長，顆粒間摩擦係數增加時，摩擦機制主控能量損失，沉積情況較為飽滿。因地勢崎嶇形成的自然阻礙物，使得顆粒體在崩塌的過程中碰撞機制仍佔一定的影響。經由參數分析，在μ_pp=0.0875與μ_pw=0.70的條件下，堆積區的形貌最為接近實際沉積形貌。三個方向的平移與旋轉擾動速度皆呈現馬克士威爾分佈，而崩塌後24sec的y方向與z方向平移擾動速度分佈峰值分別呈現左移與右移的現象，原因皆是此瞬間部分顆粒體已經開始沉積。粒子溫度分佈、配位數分佈、粒子體積佔有率及von Mises應力分佈皆隨著顆粒體崩塌的過程有所變化，從坡道上往下游崩塌，滑落到下游因地形阻礙而逐漸沉積，直至最後所有顆粒體堆積完成，配位數分佈、粒子體積佔有率與von Mises應力呈現正相關分佈。;This study analyzes landslide of Luhu mountain located in Nanzhuang Township, Miaoli County, and explores the landslide behavior and the sliding mechanism. This study proposes a discrete element model to simulate the landslide of Luhu mountain. The topographic data, provided by Sinotech engineering consultants, Ltd., are used as the basis for comparison. After the proposed DEM model is validated, we investigate internal physical properties, including translational velocity vector, fluctuation velocity distributions, granular temperatures, coordination number, solid fraction and von mises stress. As inter-particle friction coefficient decreases, the collision mechanism dominates the energy loss and the final deposition is much slender. In contrast, as inter-particle friction coefficient increases, the friction mechanism dominates the energy loss and the final deposition is wider. Due to the natural obstacles in the rugged terrain, collision mechanism plays an important role in the dissipation of system energy. According to parametric study, the final deposition is the closest to the actual sedimentary topography when μ_pp=0.0875 and μ_pw=0.70. The translational and rotational fluctuation velocity distributions in all three directions exhibit Maxwellian distributions. However, the peaks of the y-direction and z-direction translational fluctuation velocities at 24sec respectively show left-shifted and right-shifted phenomena, attributed to the fact that some of the particles have deposited by this moment. Internal physical properties change during landslide process, such as granular temperatures, coordination number, solid fraction and von mises stress. Coordination number, solid fraction and von mises stress show a positive correlation. |
