Experimental Research In Caves Detection With Digital Surface Wave Meter

As the mountain highways develop rapidly and the mileage of operating roads increases vastly,there does exist many hidden dangers in the bases of all kinds of highway structures,and various diseases has appeared gradually,such as subgrade settlement karst collapse,and underground cavern like underground vacant areas.All these will make the bases produce excessive uneven settlement,which lead to the incline of the top structures,or make the top structures produce additional stress,which will result in house and bridge collapse,pavement cracking and many other problems.Those negative results will not only impede the safe operation and development of highway,also may lead to a huge economic loss,or even threaten people's life.However,highway construction,especially in mountainous areas will inevitably crass the regions where physical mechanic property here is weaker than the rock-soil around,like soft rock strata,underground cavern,active faults and crushed zones.In the southwest part of China,thanks to the large area of Karst landform,there must be many underground Karst caves which will seriously threaten the infrastructure including highways.Thus,it is of great significance to detect and spot these underground caves.From the above,it is of promising prospective to research and develop digital georadiodetector,improved PDS-LV and advanced imaging system.Under such background,the China Merchants Chongqing Communications Technology Research & Design Inititute Co.LTD.has invented independently digital PDS-LV.It is Chinese first PDS-LV with high precision and it detects underground caves with the method of Transient Rayleigh wave exploration.The text verifies the property of this device according to Rayleigh's rationale,and under the help of soft ware like FLAC3 D and Matlab.First of all,set a series of underground caves by FLAC3 D,and then,analyze the paramenters by F-K transform analysis and dispersion curve statistics from Matlb.By doing this,we can put forward project proposal to Rayleigh surface wave meter in detecting enderground caves.The text choases a hill in Yaque village,Gulu town,Yubei district,in Chongqing as test site.Here we dig a cave(4*4*20m)at a depth of 20 m below the surface as our detection object.According to the result of forward modeling,detect the cave with the the Rayleigh device,anlyze the record of seismic wave and finally get the dispersion cave.The result suggests that the Rayleigh device can detect the underground cave exactly.Finally,comparing the results of forward modeling and inverting medeling.We can say that the device is reliable and it can be used in the project after improved.Meanwhile,the result proves that the models built in the text and parameters set in the text are carrect.