Sanjeev SumanKhatri, Shubham2019-01-282019-01-282018-08http://krishikosh.egranth.ac.in/handle/1/5810092656In the design of structures like buildings, bridges, dams etc., the subsurface soil exploration and testing become an essential part of the design so as to decide the suitability of soil strata for the particular structure. The Geotechnical field and lab testing are usually done to find the parameters of soil governing its strength’s behavior. Prior to design and constructions often geotechnical lab testing suggests that a site’s soil should be stabilized or not to improve its shear strength, stiffness, and permeability etc. At the time of planning and estimate of a structure, soil properties are required for estimating the structural quantities to be constructed upon the soil subgrade under consideration. Due to the limited availability of time and absence of data, there occur large errors in estimation. Therefore there is a vital need for some sub-surface soil properties mapping so as to come up and provide a cheap and reliable source of Geotechnical data to the engineers in the form of digital soil maps. In this regard, Digital Soil mapping using GIS can be a used as a reliable as well as an effective source of mapping soil properties. Maps of Geotechnical properties like Specific Gravity, Maximum Dry Density, and Optimum Moisture Content of soil of an area are produced by using Spatial Interpolation methods for their ready use in Civil Engineering constructions using Geographical Information System (GIS). GIS provides an easy to use atmosphere for geospatial analysis of different soil properties. The main aim of the study is to predict the spatial variability of the geotechnical properties of soil using well known spatial interpolation methods like Inverse Distance Weighted (IDW). The methodology of the study includes the development and digitization of the study area using GIS. The map of study area of Udham Singh Nagar district of Uttarakhand state was downloaded from Survey of India Website, Google map Customizer, and India’s ISRO Geoportal Bhuvan. The base map was Georeferenced and digitized up to tehsils and village level and then divided into rectangular grids having known latitudes and longitudes of soil sampling points. After built up of a digitized base map of the study area and digitized soil sampling points, next step was to collect soil samples for testing and determining their geotechnical properties. The handheld Garmin’s Global Positioning System (GPS) Receiver was used to reach the known latitudes and longitudes of known sampling points of grid and soil samples were collected. The data was then provided to ArcMap Database to prepare thematic soil maps. IDW method of spatial interpolation was applied for preparation of thematic maps of soil properties. The soil of the area was also described and distinguished using various limiting criteria’s of soil properties governing soil strength. The risk areas were also identified using the same criteria’s of soil properties. The accuracies of predicted soil properties were determined using the Cross-Validation method which provided Root Mean Square Prediction Error (RMSPE). Cross-validation helped find the accuracy of predictions using the same dataset, thus helped in avoiding more sample collection and testing for validation. The methodology presented in this study can be used to create thematic maps of soil properties at a much larger scale. Different methods of spatial Interpolation like IDW, Kriging, and Splines etc. can be used to predict soil properties at other locations and predicted surfaces from different methods can be compared for more accurate prediction. The thematic maps prepared can, therefore, provide a means of a reliable source of information for engineers at the time of planning and development of detailed project reports when data is not easily available and thus the system can act as a source of guidance for future steps.ennullThesis