Experimental Testing of Ground Improvement Technique on Swat Motorway

Abstract

Swat Expressway is an 81 kilometre long four lane under construction highway in the Khyber Paktunkhwa province of Pakistan. It stretches from Nowshera to Chakdara in Lower Dir. The project was inaugurated in August 2016. The project will be of high value to China Pakistan Economic Corridor and is expected to be completed in 15 months. During the initial geotechnical investigation of the site, it was found near bakhshali interchange that water table is only 1.5 meters below the ground surface which would certainly lead to excessive settlement if no arrangements to solve the issue were made. Saturated soils have a long consolidation period due to permeability and it must be reduced to a considerable amount to allow the construction of highway. There are a number of techniques used to improve such grounds which include sand drains, stone columns, cement grouted piles, chemical stabilization and many more. Out of various available techniques three techniques (Sand drains, Stone columns & Lime stabilization) were chosen to analyze the effect of these techniques on strength of soil. For the aforesaid purpose, a model was constructed to check the effect of these techniques on soil bearing strength. Model may be used a number of times for any type of soil and conditions encountered on site The authors believe that research on the techniques chosen to solve the problem will be enhanced by the model constructed where soil strength before and after application of ground improvement techniques can be tested by scaling down the site conditions. Research will lead to give the most feasible ground improvement technique for the encountered site conditions and problems