Geotechnical investigation for left marginal and right marginal bund of punjnad headworks

Abstract

The Executive Engineer, Punjnad Headworks Division requested for this assignment to Physics Directorate of Irrigation Research Institute, Lahore to conduct Geo-Technical Investigations to be carried out in field as well as in lab for LMB and RMB of Punjnad Headworks Total 50 sites were referred where drilling has been done at top of flood bund upto 35 ft. Activities including collection of disturbed and undisturbed soil samples, field compaction test, monitoring of groundwater levels, observation of geometrical parameters, collection of groundwater samples for chemical testing and site inspections/surveys have been carried out by the experts of Irrigation Research Institute in collaboration with the field engineers at LMB and RMB of Punjnad Headworks. Different laboratory tests including Grain size distribution, Atterberg’s Limits, Modified Compaction Test, Direct Shear Test, Unconfined Compressive Strength Test, Permeability Test and Geochemical Analysis of soil and water samples have been performed with great care and accuracy using standard procedures to determine different parameters of soil of the bunds and soil under the foundation of the bund etc. Multi criteria analysis is performed using different characteristics including soil texture, percentage compaction, Plasticity Index, Permeability, unconfined compressive strength, pin hole test and angle of internal friction to find out the River Embankment Breaching Vulnerability Index (REBVI). Ranks ranging from 1 to 6 have been assigned to these parameters (1 being most effective and 7 being least effective). Resultant values of each parameter have been assigned weights ranging from 0 to 6 (0 means least vulnerable and 6 means very highly vulnerable). Results of cluster analysis on the basis of REBVI have indicated that out of 50 sites, 9 (18%) are very highly vulnerable, 12 (24%) are highly vulnerable, 21 (42%) are moderate vulnerable, 8(16%) are less vulnerable and no site was found in very less vulnerable range.