灾难性高位滑坡致灾机制及对山区建筑的损毁模式研究

The catastrophic high-position landslide is a common geo-hazard. The serious casualties of catastrophic landslides rusult from that landslides damaged the buildings in mountainous areas, but, in general, the disaster mechanisms are greater emphasized in the study. The disaster process of landslide include rock and soil mass movement, interaction between soil and building structure, component failure and building damage. The dynamics can not be fully showed based on the study of hazard-affected bodies by the rigid structure or simplified model. In addition, because the mechanisms of landslide disasters differ from the earthquake, the seismic design standards of building can not effectively meet the requirements of landslide disaster prevention and reduction. Due to the insufficient of the landslide damage mechanism in the rural construction of mountainous areas, the buildings lack of design, construction and planning of disaster-resisting performance. Therefore, in the project, Taking the topography of catastrophic high-position landslide in aggregated distribution and widely existing structures of buildings in mountainous area as the objects, the disaster energy of high-position landslides, interaction between soil and building structure, structure dynamics responses and damage modes will be studied. The results will reveal the distributions and evolution of landslide disaster energy on the moving routs and times, dynamic responses and damage modes of buildings. The results can provide theoretical supports and scientific basis for designs and transformation of disaster-resisting performance, quantitative risk assessment of landslide and disaster reduction strategies of mountain building.

灾难性高位滑坡是一类常见的地质灾害，目前研究侧重于自身灾害机理的分析，但其导致严重人员伤亡的关键在于滑坡对山区建筑的损毁。灾难性高位滑坡的致灾过程包括岩土体运动、岩土体与建筑结构相互作用、建筑构件的失效破坏和建筑整体损毁，而基于刚性结构或简化的承灾体模型研究不能完全揭示这一过程的动力学特征；并且滑坡和地震对建筑的致灾机理不同，抗震设计标准不能有效地达到滑坡防灾减灾的要求。由于滑坡对山区建筑致灾与损毁机制研究不足，山区建筑普遍缺乏抗灾性能的设计建造和规划布局。本项目以山区建筑集聚区的高位滑坡地形和广泛存在的建筑结构形式为对象，研究高位滑坡致灾能量分布-岩土体与建筑结构相互作用-结构动力参数-建筑损毁机制的灾害过程与机理。揭示滑坡致灾能量在运程和时程上的分布演化、山区建筑的结构动力学响应与损毁模式，为滑坡灾害定量风险评估、山区建筑的抗灾性能设计改造与减灾对策提供理论支持和科学依据。

灾难性高位滑坡的致灾机制及其对山区建筑的损毁常导致严重的人员伤亡和失踪，本项目研究明晰了高位滑动、有利的场地地形、巨大的冲击能量是控制其致灾机制的主要因素；建立了滑坡运动距离的非线性回归经验模型，明晰了阶段运动特征；揭示了典型灾难性高位滑坡运动速度和厚度的时程运程分布演化、运动能量沿程转化和峰值动能，其冲击荷载可达1～3MPa、单位运动能量达10MJ，对山区建筑的冲击力可达100MN。阐明了高位滑坡导致灾难性后果的主要原因在于损毁的山区建筑分布于岩土体高速运动、高致灾强度和大于建筑高度的运动厚度区域。. 通过建立深度方向（Ns）和流动方向（Nl）颗粒分选的无量纲数，揭示了Ns和Nl的值越高，粒径越大的颗粒将在更快的时间和更高的位置产生冲击作用，颗粒分选程度并不与冲击力的大小呈正相关关系；颗粒级配及其位置影响了岩土体的颗粒分选、冲击力和能量演化，大粒径和中等粒径颗粒均可能产生强、超强力链，其产生概率与靠近初始表面位置相关；不同强度的力链在时程上呈现的不同优势方向表明了岩土体颗粒间传力机制的变化。. 提出了新的峰值冲击力和连续冲击力模型以计算法向冲击力、切向冲击力、冲击力作用高度、运动和堆积参数，当其基底反力作用位置为停滞区长度的1/2~2/3时，可估计由动态和静态分量组成的法向冲击力；并揭示了不同地形条件下坡脚位置的冲击力时程分布及其峰值冲击力衰减速率。. 明确了灾难性高位滑坡对山区建筑损毁模式，即高速运动区域两侧的冲击局部损毁、高速运动区域的完全损毁掩埋、堆积体前部的高速冲击损毁和低速推移损毁。揭示了岩土体不同冲击速度和厚度作用下框架结构的损毁模式及其剪切破坏-塑性铰链失效-逐步倒塌损毁过程、砌体结构的破坏-解体-推移的损毁模式。. 项目研究揭示的灾难性高位滑坡运动-冲击-山区建筑损毁的过程及机制，为评估潜在滑坡致灾机制，提高山区农村建筑抗灾性能的设计、改造和规划布局提供了理论支撑。