Approbation of seismic and electrical geophysical techniques complex for solving the permafrost monitoring problems on the pile-foundation building
In the urban conditions in Salekhard city, a complex of methods, including electrical resistivity tomography (ERT), ground penetrating radar (GPR), a seismic survey on refracted waves (REF), on surface waves (MASW) and the standing waves selection, was tested on solving geocryological problems and monitor the permafrost at the building base. As a model object, a residential building on a pile foundation, built according to the principle I and equipped with a continuous geothermal monitoring system, was chosen. It has been established that the ERT, REF, and MASW methods are ineffective in the conditions of a reinforced concrete pile foundation in a grillage and a concrete floor screed with a layer of loose bulk soil under it. The best result was shown by GPR at frequencies of 150 and 400 MHz and seismic exploration with the standing wave selection. A combination of these methods is recommended for determining the upper permafrost boundary under buildings, determining the actual piles-length, the quality of their fixing, assessing the water content of soils in the area around the piles, and establishing the residual building life.