近断层强震对高速远程滑坡运动行为的作用机制研究

Large-scale landslides, which are frequently occurred in the near-fault regions, present high speed, long runout and serious destruction under near-fault strong earthquakes. However, current researches of high-speed and long-runout landslide movement are lack of considering the influences of near-fault strong earthquakes. Hence, based on the requirement of earthquake prevention and disaster reduction in China, this project aims to study the mechanism of near-fault strong earthquakes to the movement of high-speed and long-runout landslides. The influences of earthquake type, component and peak value to the velocity, distance and deposition geometry of landslides will be studied using shaking table tests with recorded Wenchuan earthquakes as input loadings. The physical model tests will quantitatively reveal the mechanism of near-fault strong earthquakes to the movement of large landslides. Then on the basis of these, a high-performance numerical model for simulation of landslides movement by considering the effect of near-fault earthquakes will be developed using MPS method. The effectiveness and accuracy of this numerical model will be verified and validated using aforementioned large shaking table tests. Moreover, the proposed numerical method will be further applied to model the practical cases induced by Wenchuan earthquake to evaluate its engineering applicability. The research achievements of this project, which has significant scientific value and wide application prospects, will provide a strong promotion to the prevention and mitigation of geo-disasters in earthquake-prone zones.

近断层区域频发的大型滑坡灾害，由于受近断层强震的影响，表现出运动速度快、滑程远、破坏力强等突出特点，导致严重的人员伤亡与财产损失。本项目立足国家防震减灾的重大需求，针对当前高速远程滑坡运动研究中对近断层强震影响考虑不足的现状，拟围绕“近断层强震对高速远程滑坡运动行为的作用机制”这一关键科学问题，开展深入研究：采用振动台试验，以实测汶川地震动作为输入动荷载，定量分析地震动类型、各方向分量及峰值对滑坡运动速度、距离及堆积形态等的影响，揭示近断层强震对高速远程滑坡运动的作用机制；在此基础上，拟基于移动粒子半隐式法构建可考虑近断层强震作用的滑坡运动高性能数值模型，结合模型试验检验该模型的准确性和有效性，进一步通过分析汶川地震典型滑坡验证该模型的工程适用性，为滑坡运动分析提供先进数值方法。本项目具有重要的科学理论价值和广阔的工程应用前景，成果可为我国地震易发区的防灾减灾提供有力的科学依据。

近断层区域频发的高速远程滑坡，由于受具有脉冲特性的近断层强震影响，表现出超强的运动特性和致灾能力。本项目立足国家岩土工程防震减灾重大需求，综合采用振动台试验与数值模拟等手段开展了系统研究，顺利完成了申请书中的研究内容。取得的成果具体如下：（1）研发了适用于模拟近断层地震作用下土体大变形流动行为的模型试验系统，包括全自动模型箱、高精度数据采集系统等，实现了近断层地震作用下土体大变形流动的准确模拟，该系统目前已授权国家发明专利一项（ZL 201811554680.6）；（2）基于大型振动台模型试验，率先发现了近断层脉冲地震动具有显著的致灾增强效应，该成果对于认识地震触发滑坡的高速远程机理这一难题具有推动作用，具有较高的学术价值；（3）基于数值模拟研究，阐释了近断层脉冲地震动增强土体大变形流动灾害效应的机制：脉冲地震动可激发垂直于流动方向的质量输运，能够显著降低颗粒系统的能力损耗，从而增强其运动特性及致灾能力。因此，本项目研究成果不仅丰富了地震触发滑坡灾害的远程运动机理，同时，该研究成果可为此类灾害的防灾减灾工作提供理论基础。