基于噪声成像及微地震监测的滑坡体内部变形时空演化规律研究

The study on internal deformation characteristics of landslide plays an important role on understanding the mechanism of landslide instability as well as monitoring and predicting of the hazard. The methods existed mostly focus on the surface displacement deformation of landslide, ignoring the analysis of internal failure deformation mechanism with the problem of hysteresis in hazard forecasting. As the landslide instability accompanies with the continuous strata structure changes and microcracking phenomenon, the ambient noise imaging and microseismic monitoring technique, which can obtain the velocity distribution underground and identify the potential sliding surface respectively, is taken as an effective tool to study the internal deformation rules of landslide. In this study, we try to obtain the 3-D velocity structure of landslide in different stages by surface wave imaging using ambient noise data, providing reference data for the analysis of landslide deformation. Based on the velocity model above, we locate the microseismic events induced by internal damage deformation of landslide in order to describe the spatial-temporal distribution characteristics of internal cracks. We aslo extract the time-frequency parameters of ambient noise data and microseismic events respectively by generalized S transform considering that the seismic wave contains the instant information of internal damage. Finally we establish spatial-temporal evolution relationships between the velocity structure, microseismic events, time-frequency parameters and internal deformation of landslide, and then make the dynamic monitoring of landslide instability coming true from the point of geophysics and geology, and provide scientific basis for the prediction of landslide hazard.

滑坡内部变形特征的研究对正确认识滑坡成因机理及灾害监测预报具有重要意义。现有方法多聚焦于滑坡表面位移变形研究，忽略了对其内部破坏变形机理的分析，存在灾害预报滞后性问题。滑坡灾变伴随着持续的内部地层结构变化与微破裂现象，因此利用噪声成像反演地下速度分布，并通过微震监测识别滑坡体内部潜在滑动破裂面，可作为研究滑坡内部变形演化规律的重要手段。本项目拟采用噪声面波成像方法获取不同时期滑坡内部三维速度结构，为滑坡内部变形分析提供参考数据；在此速度模型基础上，对滑坡内部破坏诱发的微震事件进行定位，并描述其裂缝演化的时空分布特征；鉴于波形本身包含滑坡内部瞬时破坏信息，应用广义S变换提取噪声数据与微震事件的时频参数，以期建立滑坡体速度结构、微震事件、信号时频参数与滑坡内部变形的时空演化关系，进而从地球物理学和地质学角度实现滑坡失稳动态监测，为滑坡灾害预报提供科学依据。

滑坡内部变形特征的研究对正确认识滑坡成因机理及灾害监测预报具有重要意义。现有方法多聚焦于滑坡表面位移变形研究，忽略了对其内部破坏变形机理的分析，存在灾害预报滞后性问题。滑坡灾变伴随着持续的内部地层结构变化与微破裂现象，项目选择潜在滑坡地质区域布设密集台阵进行连续地震数据采集，设计并开发噪声面波成像程序反演不同时期滑坡内部三维速度结构，在此速度模型基础上，进一步完成滑坡体内部破坏诱发的微震事件识别与双差定位（HypoDD）工作，将背景噪声成像与微地震定位技术结合，同时获得滑坡体内部速度结构与裂缝演化的时空分布特征参数，成果揭示了试验区滑坡潜在滑动面形态以及内部裂缝产状；本项目研究建立了滑坡体内部速度结构、微震事件与滑坡内部变形的多参数时空演化关系，能够为滑坡灾害失稳预报提供更及时准确的科学依据。