| Qingdao Metro line3was designed underground with about24.9km entire long,22stations,"West-East-North-West" to cross the urban area of Qingdao. Subwaytunnel construction began in early2011, and the work of geological prediction withground penetrating radar subsequently expanded. Subway tunnel roof was buried lessthan30m, and geological disasters substantially developed in the consequence of theformation change. Thus creating different GPR anomaly profile of geologicaldisasters body is the key to ensure effectiveness of detection. In addition, closed spacestructure of the tunnel and the steel arch around the field, construction machinery,electrical equipment, etc. made GPR detection signal impacted by the seriousinterference, even the valid signal completely being covered, causing interpretedmiscarriage of justice.To address the key technologies mentioned above in GPR geological prediction,this paper analyzed236GPR profiles measured in Qingdao Metro Line3, summed upthe characteristics of the typical geological anomaly reflected signals and interferencesignals; compared theoretical calculations and determined the signal recognitionsectional characteristics. In the end, the noise signal and de-noising for GPR methodwere analyzed, initially identifying noise interference patterns and finding ways tocircumvent. The main research results obtained are as follows:1. Determined different signal characteristics and water-rich rock weatheringdegree, explained the construction environment GPR interference during detection;2. Achieved GPR standard profile of typical geological body with forwardcalculation and illustrated the geological characteristics of each reflected signal;3. Determines the detection process, steel arch, shape and construction ofmechanical interference caused by noise interference range;4. Conventional high-pass, low-pass, band-pass filtering is not obvious to thenoise suppression, vertical tunnel face acquisition mode is helpful to avoid the interference source in response to changes in the direction of the antenna. |
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