Sci.Int (Lahore), 25(4), , 2013 ISSN ; CODEN: SINTE 8 531

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1 Sci.Int (Lahore), 25(4), , 2013 ISSN ; CODEN: SINTE PROFILING AND ZONING OF GEOTECHNICAL SUB-SOIL DATA USING GEOGRAPHIC INFORMATION SYSTEM Mahmood Ahmad*, Qaiser Iqbal and Fayaz Ahmad Khan Department of Civil Engineering, University of Engineering and Technology Peshawar, Pakistan *Contact: engrkhattak@hotmail.com ABSTRACT: This research paper presents a compendium of the geotechnical sub-soil data profiling and zoning of the major urban settlements of Peshawar using Geographic Information System. Significant geotechnical properties of the under study area soils i.e., Zone 5 & 6 in Peshawar were assessed through one hundred and three different standard penetration test reports up to the depth of 1 m and 3 m. The qualitative description of the sub-soil data was manipulated into the quantitative figures by means of coding in order to interpolate the soil class distribution for the preparation of geotechnical zonation maps. This work is helpful for balancing of cost and acquiring the significant reliable data regarding soil class distribution, classification charactrestics, shear strength charactrestics and bearing capacity of soils during feasibility and preliminary design stage of the project. Keywords: Geotechnical properties, Geotechnical zonation maps, Interpolation and Urban settlements. List of symboles/abbrevations CL-ML Silty Clay or Clayey Silt CL Clay c Cohesion or Inter-Particle Attraction DEM Digital Elevation Model GZMs Geotechnical Zonation Maps GIS Geographic Information System GW Well Graded Gravel GP Poorly Graded Gravel GC Clayey Gravel GTS General Topographic Sheet GPS Global Positioning System GM Silty Gravel IDW Inverse Distance Weighted Interpolation LL Liquid Limit of Soil ML Silt NSL Natural Surface Level PL Plastic Limit of Soil PI Plastic Index of Soil = LL PL PCF Pounds per Cubic Foot SPT Standard Penetration Test SP Poorly Graded Sand SM Silty Sand SRTM Shuttle Radar Topographic Mission TSF Tons per Square Foot USCS Unified Soil Classification System ϕ Angle of Internal Friction 1. INTRODUCTION The profiling and zoning of geotechnical sub-soil data is often considered as one of the very important information for the planning and a construction projects in civil engineering works. Data availability can cut the expense of the projects and also reduce time, particularly during feasibility and planning stage. In past few years, the numbers of construction projects in Peshawar have increased rapidly. Consequently, the number of soil boring reports has been accrued largely. The presentation of already available subsoil data in a user friendly format will enable the geotechnical and civil engineers beforehand to plan the detail geotechnical investigation based on the provided soil profile and Geotechnical Zonation Maps (GZMs). The GZMs and sub-soil profile will facilitate the geotechnical engineers for preliminary design of foundations, feasibility study and preparation of rough cost estimates for the proposed projects. The geographic information system (GIS) is a valuable tool for geotechnical engineers, not only for nondata area prediction but also used to interpret the complex data area with reliability and accuracy [1]. The GZMs have not yet been prepared by any group, agency or individual at Khyber Pakhtunkhwa level and this work is the first step in this perspective. Establishing a GZMs and soil profile of Peshawar urban settlement can be very useful during preliminary planning, designing and feasibility studies of various engineering projects in Peshawar. In several countries of the world, proper guidelines are already available to practicing engineers and forerunner geotechnical engineers in the form of maps for geotechnical design purposes [2]. This research is focused for general establishment of geotechnical appraisal for construction projects in Peshawar urban settlements. Geotechnical subsoil data currently available at Soil mechanics and Highway Engineering Laboratory, University of Engineering and Technology Peshawar is utilized for preparation of these maps. 2. OBJECTIVIES OF THE STUDY The research study is designed to prepare sub-soil profile, GZMs and to furnish sufficient necessary reliable data regarding percentage of soil class distribution, classification charactrestics, shear strength charactrestics and bearing capacity of soils in the selected under study area of the Peshawar urban settlements. This research work will assist the geotechnical and civil engineers beforehand to plan the detail geotechnical investigation based on the provided subsoil profile and GZMs. 3. DESCRIPTION OF THE STUDY AREA The study area consists of Peshawar urban settlements i.e. Zone 5 and 6 having two hundred and eighty nine square kilometers area located within Latitudes to 34 4 N and Longitudes to E (Fig. 1). The study area

532 is characterized by broadly flat topography with gentle undulations. The Peshawar valley is covered with unconsolidated deposits of sand, silt and gravel [3]. Fig.

2 532 is characterized by broadly flat topography with gentle undulations. The Peshawar valley is covered with unconsolidated deposits of sand, silt and gravel [3]. Fig. 1: Land Cover Map of Peshawar District with Study Area Zones. 4. METHODOLOGY During geotechnical zonation mapping exercise, the very first step is the digitization of roads (metal and un-metal), rivers, urban settlements and boundary of the district Peshawar which was carried out from the geo referenced General Topographic Sheet (GTS) prepared by Survey of Pakistan in 1986 using a scale of 1:5000. Digital Elevation Model (DEM) of the Peshawar district at 10 m interval was created from the National Aeronautics and Space Administration, Shuttle Radar Topography Mission (SRTM) 90 m interval data for ascertaining the depth of the bore logs from the Natural Surface Level (NSL). Positions of Standard Penetration Test (SPT) soil samples were ascertained from Global Positioning System (GPS) readings and assigned to the corresponding latitudes and longitudes. Using Inverse Distance Weighted (IDW) interpolating technique, the soil classes were coded as (1,3,6,2,7,8,9,10 and 11) owing to facilitate the analysis of the soil class distribution, that were found in the soil bore logs [4]. They are: Clayey sand (SC), Clay (CL), Silty clay or Clayey silt (CL-ML), Poorly graded gravel (GP), Clayey gravel (GC), Silt (ML), Silty gravel (GM), Silty sand (SM), and Poorly graded sand (SP) ISSN ; CODEN: SINTE 8 Sci.Int (Lahore), 25(4), , 2013 respectively. Soil class distribution was digitized after interpolation and finally layouts of all layers of the study area (Zone 5 & 6) were made. The GZMs were enlarged to a scale of 1:70,000.Total one hundred and three SPT reports were examined for the preparation of GZMs at depth 1 m and 3 m, while soil profile strata chart was also prepared for the selected section. The database table used for the analysis examination was constructed from: Borehole ID, Project Name, Coordinates, SPT N-values, Soil class, Atterberg Limits, Safe bearing capacity and Shear strength characteristics. 5. RESULTS 5.1 Percentage of Soil Class Distribution in the Study Area At depth 1 m in Zone 5, clay and silty clay or clayey silt (CL, CL-ML) cover 50 % area,silt (ML) covers 1 % area, clayey gravel and poorly graded gravel (GC, GP) cover 49 % area. clay and silty clay or clayey silt (CL, CL-ML) predominant at depth 3 m in geotechnical zonation map which shows a higher percentage of 62.2 %, Poorly graded sand (SP) shows 0.7 % area, Clayey gravel and poorly graded gravel (GC, GP) cover 37.1 % area. Consequently, at depth 1 m in Zone 6, clay and silty clay or clayey silt (CL, CL-ML) cover 80 % area, clayey gravel and poorly graded gravel (GC, GP) cover 20 % area. While at depth 3 m clay and silty clay or clayey silt (CL, CL-ML) cover 87 % area, clayey gravel and poorly graded gravel (GC, GP) considerably reduced from 20 % area - at depth 1 m in Zone 6 to 13 % area (Fig. 2-5). 5.2 Classification Characteristics The results of the SPT show that the liquid limits ranges from 18.4 % to 33.1 %, plastic limit from 14.9 % to 21.1 %, plasticity index 0.8 % to 13.2 % and the moisture content ranges from 0.5 % to 34.8 % in Zone 5. While in Zone 6 the liquid limits ranges from 18.1 % to 32.2 %, plastic limit from 15.1 % to 21.2 %, plasticity index 0.6 % to 14.1 % and the moisture content ranges from 1.5 % to 52.5 %. Generally, Coarse - grained soils (gravels etc) are not very sensitive to moisture change, whereas fine - grained soils (clays etc) are sensitive to moisture changes. Cohesionless soils have plasticity index, theoretically, is zero. 5.3 Shear Strength Characteristics Direct shear test is employed for determining the shear strength parameters, cohesion or inter-particle attraction (c) and the angle of internal friction (ϕ). The results revealed that the cohesion (c) in Zone 5 ranges from to PCF while in Zone 6 ranges from 445 to 1427 PCF. The internal friction angle (ϕ) in Zone 5 varies from 11.3 to 40.8 while in Zone 6 its varies from 22 to Owing to the increasing amounts of the fines-sized particles, such as clay, the cohesion of soil increases [5]. Shear strength characteristics of the fine grained soils are influenced greatly by moisture content variations. 5.4 Bearing Capacity The load carrying capacity of the foundation soil and rock

Sci.Int (Lahore), 25(4),531-537, 2013 ISSN 1013-5316; CODEN: SINTE 8 533 without causing intolerable settlement of the structure is called bearing capacity [6].

91 m (3 ft) and width 3 ft in Hayatabad for an estimated settlement of 1 in recoded due to the poorly graded gravels and clayey gravels (GP & GC) that reveals the increasing trend of angle of

3 Sci.Int (Lahore), 25(4), , 2013 ISSN ; CODEN: SINTE without causing intolerable settlement of the structure is called bearing capacity [6]. Tolerable settlement would not affect the function or structural integrity of the structure and is commonly set is about 1 inch. The highest value of the safe bearing capacity was 2 TSF at depth 0.91 m (3 ft) and width 3 ft in Hayatabad for an estimated settlement of 1 in recoded due to the poorly graded gravels and clayey gravels (GP & GC) that reveals the increasing trend of angle of internal friction resulting increase in bearing capacity of the soil in Zone 5. In Zone 6 the minimum value of safe bearing capacity at depth 0.91 m (3 ft) and width 3 ft for an estimated settlement of 1 in was 0.2 TSF (Fig. 6-7). 5.5 Sub-Soil Profile Soil profile is a vertical cross section of the actual soil strata at a given site showing sequence and thickness of soil layers below the natural surface level [7]. The sub-soil profile section AA covers the area from Hayatabad to Gulbahar in Peshawar. The sub-soil profile clearly indicates the presence of surface stratum of gravels and silts in Zone 5 while in Zone 6 the coarse grained soils i.e. gravels are overlaying over clay (Fig. 8). Ground water table was not encountered to the exploration depth of 7 m in the sub-soil profile map. Fig. 2: Geotechnical Zonation Map (GZM) at Depth 1 m (Zone 5) Fig. 3: Geotechnical Zonation Map (GZM) at Depth 3 m (Zone 5)

4 534 ISSN ; CODEN: SINTE 8 Sci.Int (Lahore), 25(4), , 2013 Fig. 4: Geotechnical Zonation Map (GZM) at Depth 1 m (Zone 6) Fig. 5: Geotechnical Zonation Map (GZM) at Depth 3 m (Zone 6)

Sci.Int (Lahore), 25(4),531-537, 2013 ISSN

5 Sci.Int (Lahore), 25(4), , 2013 ISSN ; CODEN: SINTE Fig. 6: Bearing Capacity in TSF Zonation Map (Zone 5) Fig. 7: Bearing Capacity in TSF Zonation Map (Zone 6)

6 536 ISSN ; CODEN: SINTE 8 Sci.Int (Lahore), 25(4), , 2013 Fig. 8: Sub-Soil Profile Map, Section AA (Zone 5 & 6) 6. DISCUSSION AND CONCLUSIONS It was observed during analysis that SPT N-values are directly proportional to the soil strength and depth i.e. the greater the N-values, the stronger the soil mass. The line slope (m) shows upward trend which means that the ranges from to for both zones i.e. 5 & 6. The following range for the goodness of fit was considered, i. R 2 > 0.95 means excellent correlation exists between variables [8]. The Fig. 9 showing an excellent correlation between the depth versus average SPT N- values of Zone 5. ii. R 2 = 0.90 to 0.95 means very good correlation exists between variables [8]. The Fig. 10 showing a good correlation between the depth versus average SPT N- values of Zone 6. Fig. 10: Graph Showing Regression Analysis between depth versus Avg. SPT N-value of Zone 6 Fig. 9: Graph Showing Regression Analysis between depth versus Avg. SPT N-value of Zone 5 Conclusion was made that the SPT N-values increase with depth owing to pressure, compaction and increase in content of clay and clayey silt or silty also the high value of friction angle indicates dense conditions in the granular soils. The relationships found up to 5 m depth are of straight line equations with selected intercepting values and are as shown in graph equations.

7 Sci.Int (Lahore), 25(4), , 2013 ISSN ; CODEN: SINTE This research collates the available one hundred and three geotechnical sub-soil SPT reports of Peshawar urban settlements. The standard penetration N-values is an index which is directly proportional to the soil strength. The work will assist as a ready reference guide for practicing geotechnical Engineers and Researchers in Peshawar. This is valuable in the aspect that, it will reduce considerably the initial costs of new proposed projects which is to initiate in areas covered in this paper. 7. REFERENCES [1] Suwanwiwattana, P., Chantawarangul, K., Mairaing, W., & Apaphant, P., The development of geotechnical database of Bangkok subsoil using GRASS-GIS, 2001, November, pp [2] Hayat, K., 2003, Geotechnical zonation and their relation to geology of Pakistan, Ph.D. Thesis, University of the Punjab, Pakistan. [3] Aslam, M., Hussain, A., Ashraf, M. & Afridi, A. G. K., 2006, Geological Map of North West Frontier Province, Geological Survey of Pakistan. [4] Aguib, A., 2005, GIS application for constructing knowledge base and representing 3d geotechnical data, Proceedings of 11th International Colloquium on Structural and Geotechnical Engineering, Ain Shams University, Egypt. [5] Jumikis, A. R., Soil Mechanics, Neeraj, Galgotia, New Delhi, p. 33. [6] Chandra, K. U., Soil mechanics and Foundation Engineering, PHI learning private limited, New Delhi, P [7] Jumikis, A. R., Soil Mechanics, Neeraj, Galgotia, New Delhi, p. 32. [8] Hoffmann, J. P., Beacom, K. & Cooper, A., Linear Regression Analysis : Assumptions and Applications.

Solution:Example 1. Example 2. Solution: Example 2. clay. Textural Soil Classification System (USDA) CE353 Soil Mechanics Dr.

Solution:Example 1. Example 2. Solution: Example 2. clay. Textural Soil Classification System (USDA) CE353 Soil Mechanics Dr. CE353 Soil Mechanics CE353 Lecture 5 Geotechnical Engineering Laboratory SOIL CLASSIFICATION Lecture 5 SOIL CLASSIFICATION Dr. Talat A Bader Dr. Talat Bader 2 Requirements of a soil Systems Why do we need