Introducing a Comprehensive Geological and Geotechnical Classification for Urban Planning and Design, A Case Study in Isfahan (Iran)

Combining geological and geotechnical data is quite beneficial for planning and designing urban development projects. Isfahan city is located on Jurassic shale and sandstone and Quaternary deposits. It is important to identify the engineering properties of these rock units and soil layers to distinguish them in construction projects. In this research, all types of rocks and soils in Isfahan city are identified precisely. Besides, the geological properties including their origin, thickness and extent are determined. To analyze the subsurface layers and determine their physical and engineering properties, 23 pits were excavated in various locations and in situ tests were performed. In addition, for comparing, completing and identifying layers in higher depth, geotechnical data of 384 boreholes (which have been drilled in civil projects) were used. After analyzing all data by means of SPSS software, The range and average of the physical and engineering properties of area's soil layers such as density, atterberg limits, uniaxial strength, standard penetration test number, undrained and effective internal friction angle and cohesion, deformation modulus, compressibility, swell coefficients and rock units parameters such as density, point load, slake durability and elastic modulus were separately determined based on laboratory and in situ tests. Finally, a comprehensive geological and geotechnical classification and geotechnical zoning map of Isfahan city are suggested to identify subsurface layers and their engineering characteristics. According to this map, Isfahan city is divided into seven geotechnical zones. These classification and map can be used for urban planning and development.