滑坡堰塞体河谷堆积形态特征研究

    Study on the morphological characteristics of landslide dam in valley deposition

    • 摘要: 河谷堆积形态特征是堰塞体灾害发展、演化、处置与防治的先决基础,亟待理论量化。设计了一套滑坡-堵江-成坝的堰塞体形成全过程试验装置,引入三维运动结构逆向重构技术(SfM)量化分析了滑坡堰塞体堆积形态特征;依据典型横、纵断面特征,用10个特征点、12个参量推演出滑坡堰塞体体积计算方法。试验结果及理论分析表明,滑坡堰塞体表层小颗粒集中分布于近滑侧的堆积区,大颗粒沿滑入方向向远滑侧、河谷两侧临空方向逐渐增多。当滑坡角较小时,滑源颗粒料易在近滑侧形成堆积体,坝体最低点位于远滑侧。当滑距较小时,滑坡堰塞体最高点位于河谷近滑侧;随着滑距增加,最高点逐渐转移至河道远滑侧。滑坡堰塞体横断面呈梯形,纵断面形状分为左高、中峰和右高三种类型,用10个特征点概化堰塞体堆积形态特征。利用割补法,推导出体积计算方法;引入了静态休止角、滑距和滑坡角,建立了滑坡堰塞体堆积形态特征的量化模型。试验数据表明,计算模型对正向计算的体积相对误差为-3.22~14.96%;高度、底宽和长度逆向预测的相对误差均小于15%。这表明所建立量化模型能够量化不同静态休止角、滑坡角和滑距对滑坡堰塞体堆积形态的影响,有助于评估与预测滑坡堰塞体成灾规模。

       

      Abstract: The morphological characteristics are a fundamental prerequisite for the development, evolution, mitigation, and prevention of landslide dam hazards, necessitating urgent theoretical quantification. A comprehensive experimental setup was designed to simulate the entire process of landslide-induced river blockage and dam formation. Structure from Motion of three-dimensional reverse reconstruction technology (Structure from Motion, SfM) was employed to quantitatively analyze the morphological characteristics. Based on typical cross-sectional and longitudinal profiles, a computational method for landslide dam volume was derived using 10 characteristic points and 12 parameters. Experimental results and theoretical analysis reveal that fine particles in the landslide dam are predominantly concentrated near the sliding-side accumulation zone, while coarse particles gradually increase toward the distal sliding side and the valley’s free surfaces along the sliding direction. At smaller sliding angles, the source material tends to accumulate on the near-slide side, with the lowest point of the dam situated on the distal side. When the sliding distance is short, the highest point of the landslide dam is located on the near-slide side of the valley; as the sliding distance increases, the peak elevation shifts toward the distal side of the river channel. The cross-section of a landslide dam exhibits a trapezoidal shape, while the longitudinal profile can be categorized into three types: left-high, central-peak, and right-high. The deposit morphology was generalized using 10 characteristic points. A volume calculation method was derived using the cut-and-fill technique, and a quantitative model for morphological characteristics was established by incorporating the static angle of repose, sliding distance, and sliding angle. Experimental data demonstrate that the computational model yields a relative error range of -3.22% to 14.96% for forward volume calculations, while the inverse predictions of height, base width, and length all exhibit relative errors below 15%. These results confirm that the proposed quantitative model effectively captures the influence of varying static angles of repose, sliding angles, and sliding distances on the morphology of landslide dams. This advancement provides a robust basis for assessing and predicting the disaster-scale potential of landslide dam.

       

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