Geotechnical map of Thi Qar governorate using geographical information systems (GIS)

Abstract

Lack of soil data at the site is one of the most critical problems for a geotechnical engineer. The design cannot be done without knowing the geotechnical characteristics of the area under the foundation. In this study, a geotechnical map of soil properties in Thi Qar Governorate was prepared using geographic information systems (GIS). The soil survey data for the city of Nasiriyah were taken from 423 wells from several laboratories (the Engineering Consultancy Laboratory “ECL”, the Office of Multiple Consultants, and others). They studied after obtaining it and analyzing it using the Excel program. The data were analyzed by two methods of inverse distance measurement (IDW) and inverse distance measurement tool kriging. The results of the two methods were compared in terms of accuracy to create geotechnical maps. The engineering soil properties include characteristics of Nasiriyah soil, the most important of which are dry density(γd); water content(Wc); liquid limit(L.L); ultimate bearing capacity(UBC), and standard penetration test (SPT-N). One of the most critical soil characteristics that must be taken into account is the carrying capacity of the soil. Geotechnical maps cover all studied areas and provide approximate values for missing data when creating a reliable database for Nasiriyah soils. The results showed that the values of water content at depth (0–2) m range between (15–56)%, and these values vary with depth. The dry density ranges between (12–19) kN/m3, the number of the borehole is 2.5 and exceeds 50 borehole, and the specific gravity is 2.7 ± 1. The groundwater rises in the south and decreases in the north of the governorate. The findings reveal Thi Qar ultimate bearing capacity (B.C), ranging from (200–505) kN/m2. The maximum bearing capacity in the northern region is 261–331 kN/m2, in the southern region is 327–254 kN/m2, and in the east and west of the governorate and the governorate center, it is 227–261 kN/m2.