Discussion on ‘ArcGIS mapping, characterisations and modelling the physical and mechanical properties of the Sulaimani City soils, Kurdistan Region’ by Ahmed et al. (2020b)

Abstract

The results and conclusions of the paper by Ahmed et al. (2020b) are really confusing because the information of this paper is very similar to a paper published recently by Ahmed et al. (2020a) which is about the prediction of geotechnical properties of soils in Sulaimani city, Iraq. The authors mentioned that they have collected about 630 data of Unconfined Compression Strength (UCS) tests with density tests from the geotechnical reports in a period between 2017 and 2019 which were extruded, tested and reported by the Ministry of Construction and Housing/ Sulaimni Construction Laboratories (SCL) in Sulaimani City between 2017 and 2019. We would like to inform that during that period only three of these reports were written by Dr. Maysoon Kh. Askar from Masatha Company in Iraq for SCL during 2017 without conducting any Unconfined Compression Strength (UCS) test and the other reports (about 75) were written by Dr. Alshkane as a consultant geotechnical engineer for SCL since 2018. During that period (2018 and 2019) only five Unconfined Compression Strength (UCS) tests (see Table 1) were conducted on undisturbed samples which were obtained by Shelby Tube sampler because the consistency of fine-grained soils in Sulaimani city is very hard and is mostly difficult to obtain undisturbed samples using Shelby Tube for UCS and density tests. Dr. Alshkane has only relied on Standard Penetration Tests (SPT) and plasticity index to determine the allowable bearing capacity of building foundations. In addition, the Sulaimani Constructional Laboratories (SCL) have not conducted any hydrometer tests and swelling tests for building projects and the plasticity chart was only used to find the type of fine-grained soils. The data of the paper by Ahmed et al. (2020b) are fabricated and do not represent the geotechnical properties of Sulaimani city. The authors stated that Equation (1) (presented in two forms: see Table 1 and Equation (6) by Ahmed et al. 2020b) was developed based on data collected from literature (374 data) and the geotechnical reports of Sulaimani city (630 data), but they did not give the details and the sources of the collected data from literature although their study should focus on soils of Sulaimani city as mentioned in the paper title which is the focus of their study. The range of the measured Su for Sulaimani soil was between 10 and 115 kPa whereas according to Figure 13 (Ahmed et al. 2020b) the range was from about 30 to 100 kPa. This range is not true for Sulaimani city soils (see Tables 1 and 2) because finegrained soils are generally hard and their SPT (N) is more than 10 according to our knowledge and based on Table 1 which presents that the range is from 34.5 to 324 kPa, the latter number indicates a very hard clay soil.