Study On Emergency Monitoring And Restoration Of Jiuzhaigou Core Heritage Sites After Earthquake

Jiuzhaigou was listed as the World Cultural and Natural Heritage and key area for poverty alleviation development.Unfortunately,on August 8,2017,a Ms 7.0 earthquake occurred in Jiuzhaigou and caused damage to the local landscape,including Nuorilang dam collapse and Sparking Lake dam burst.Therefore,monitoring and field survey of damaged landscape were carried out in this study.The evolution of Jiuzhaigou travertine landscape was predicted.The typical travertine samples were collected and analyzed to study the natural growth behavior of travertine,and it could be applied in the restoration of travertine landscape.After earthquake hundreds of landslides,mainly small landslides,and collapse occurred in the upper part of the mountain and loose area.The Sparking Lake and Nuorilang were the most severe damaged areas,if there are none intervention,the dam will continues to collapse due to weathering and desertification,worsely,continuous collapses not only can not protect the original landscape,but also threaten the ecological environment and the safety of scenic spots.The environmental monitoring results in four core landscapes after earthquake showed the hydrochemical changes are significant,which were mainly reflected in the increase of Ca²⁺and HCO₃^-concentration.The fluvial saturation index of calcite after earthquake was greater than 0 due to the trend of ions changed,which was conducive to travertine deposition.The porous carbonate deposition at Nuorilang and Sparking Lake,was characterized with various structure and fossils.The travertine grew under macroscopic seasonal-control,summer and autumn was precipitated period,spring and winter were weathered time.The micro-deposition process consisted of 4 steps,firstly,polymers were formed by aggregation of nano-crystals,secondly,these polymers adsorbed on organic or inorganic substrates and became the mesocrystals,thirdly,mesocrystals grew under the control of organic matter,and these oriented mesocrystals gradually became polyhedron with clear boundary or larger size irregular one.The essential conditions for neoprepitation were hydrochemistry and biology.Under the action of two factors,the damaged part could be reinforced by neodeposition and recrystallization.In the study on the feasibility of using the mixture of waste travertine and calcium-based gellant to repair,Ca²⁺-H₂O-CO₃^2-system which was result of materials dissolution reached equilibrium after 5 days,then,supersaturated setting of CaCO₃ was formed at the solid-liquid interface due to the dissolution of gellant,so crystallization grew on the surface of material was observed after 5 days.These crystals were tested to be calcite by Fourier transform infrared?FTIR?and X-ray diffraction?XRD?analysis,which was similar to that of travertine.It was proved that the repairing materials were applicable in the area.