The Zoning of Soil Strength Parameters in Rasht using Geographical Information System (GIS)

Geotechnical studies constitute a key part of civil engineering projects that have economic and qualitative implications for the structure and its safety during both construction and operational phases. In addition to requiring time and expenses, borehole drilling, soil sampling, and geotechnical testing can at times lead to irreparable losses and damage, such as the explosion of gas pipes or the collapse of adjacent buildings. For typical buildings, such tests can be skipped with the help of geographical information system (GIS) analysis functions. In this study, the geographical coordinates about the location of previous geotechnical studies conducted during the construction of residential structures have been determined, to create an appropriate database and with the use of GIS interpolation functions, zoning maps are prepared and presented to offer a general visualization of the geotechnical status of the area. Therefore, in this study, the geotechnical data of 170 boreholes drilled in Rasht, including soil strength parameters for individual soil layers to a depth of 12 m from ground level were collected and implemented in GIS interpolation functions. Thus, raster layers were created and after selecting the best interpolation method, zoning maps for geotechnical parameters were plotted. Results showed that overall, more than 99% of the study area has an SPT number higher than 10 and an internal friction angle lower than 28 degrees. Qualitatively, aggregate soils in the study area were generally composed of medium sandy soils while most cohesive soils in the area fall in the category of stiff.