Identification of geological hazards of Zarand city using geotechnical and geophysical properties of soils

Many researchers have studied subsurface stratigraphy by approaching three-dimensional geological models in recent decades to overcome the complex nature of the subsurface. In many urban areas, specific three-dimensional spatial models have been developed that are used to predict land conditions, reduce risk, and uncertainty in urban planning. In this study, geological, geotechnical and geophysical analyzes were used based on data collected from 20 geotechnical boreholes and 29 geoelectric soundings around Zarand wide. Having statistically geotechnical and geophysical parameters of the soil estimated (such as liquid limit LL%, plasticity index PI %, moisture content w%, dry density γd, soil shear strength parameters of C and ϕ◦, modified standard penetration resistance N (60) and electrical resistance of the ground Ωm) and using the weighted moving average interpolation method (kriging), two-dimensional maps and three-dimensional spatial distribution of soil properties were prepared by which the problematic soils were identified. The results of spatial distribution and trenches to a depth of 15 meters show that the soils of Zarand are of Cl, CL-ML, SC, SC-SM and ML. According to the classification maps of the dominant soil texture and density as well as ASTM regulation (2002), these soils are in the range of medium collapsibility. In addition, regarding classification map of soil corrosion obtained from moisture content and the same electrical resistance levels of the ground to an average depth of 4 meters, surface soils were mainly located in the range of moderate to high corrosive according to BS-7361 and ASTM STP 1013 standards.