| The Middle Route of South-to-North Water Diversion is a crucial infrastructural project which can be capable of optimizing the configuration of water resource in the North China Plain.The level of economic and social development improves along the route because it’s continuous,safe and stable operation.The total length of the project main canal is 1432 km,with a large spatial span and complex geological environment,which is prone to slope instability affecting the normal operation of the main canal.Therefore,it is important to carry out deformation monitoring,prediction and mechanism analysis for the canal slope.In order to study the evolution of slope deformation of deeply-excavated canal of the Middle Route of South-to-North Water Diversion,using the high accuracy,contactless and long time series monitoring characteristics of Synthetic Aperture Radar Interferometry Technology.Based on the 88 Sentinel-1A data from 2017 and 2019 to obtain and analyze the annual average deformation velocity and cumulative deformation field of the slopes on both sides.The in-situ soils in the study area are collected at different locations on the slope of deeply-excavated canal,and the mineral composition of each sample is tested separately by X-ray diffractometer to analyze the correlation between deformation and soil physical properties.Based on terrestrial climate data set V3.0 of the study area released by China Meteorological Data Service Center,Thiessen polygon method is used to calculate the regional average precipitation.The influence of precipitation on slope deformation during the monitoring period is discussed.The slope deformation prediction model taking into account the seasonal index is constructed and the slope deformation trend is analyzed.The main work of this paper is as follows:(1)Study on the spatiotemporal evolution law of slope deformation: Using deeply-excavated canal at the head canal of the Middle Route of South-to-North Water Diversion as the engineering study area,SBAS-In SAR technology is used to process the88 Sentinel-1A data to obtain the annual average deformation velocity and cumulative deformation variables of the slope of deeply-excavated canal during 2017-2019.The reliability of the monitoring results is verified with the deformation information obtained by the PS-In SAR technology,and the differences between the monitoring results obtained by the two methods are small.(2)Mechanism analysis of slope deformation: Several groups of in-situ soil samples are collected in the study area,and the mineral composition is tested by X-ray diffractometer to obtain the soil profile,mineral composition and content.The influence of precipitation on the slope deformation is investigated for nine characteristic points selected in the study area,and the mechanism of slope deformation in deeply-excavated canal of the Middle Route of South-to-North Water Diversion is revealed.The results show that the swelling soil containing illite over study area,which swells with water will cause the slope to be lifted but not affecting the overall deformation trend,and the long-time slow decline of the upper geotechnical body of the deeply-excavated canal is limited by the anti-slip piles and the extrusion is the main reason for the slope deformation.(3)Prediction model construction of slope deformation: According to the law of slope deformation in deeply-excavated canal,the correlation between slope deformation and time is analyzed,and the slope deformation prediction model with seasonal index is constructed,and the prediction accuracy of the model is evaluated by using the measured data.The results show that the overall trend of slope deformation in deeply-excavated canal can be characterized by the regression midline between the slope shape and time,and the slope deformation prediction model taking into account seasonal index can make scientific and reasonable prediction of the future deformation trend. |
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