In 1954 terzaghi has suggested a simplified approach for the design of cutoff walls considering average seepage force.
Exit gradient sheet pile wall.
Exit gradient at toe of hydraulic structure g usin computer program seep w software.
For the sheet pile wall this filter is placed over the potentially unstable prism abed in fig.
A compute the total quantity of seepage in units of ft through the soil over a 24 hour b compute the critical hydraulic gradient and factor of safety against quick sand given this.
Depended on the software program tests were carried out with three different value of each following parameter upstream sheet pile depth downstream sheet pile depth permeability for first and second soil layer depth of first and.
Exercise 14 1 derive relationship between the critical hydraulic gradient icr and porosity solution 14 1 cr also cr gs gs exercise 14 2 sheet pile wall.
Musa 2014 studied the influence of cavities on seepage under sheet pile wall for hydraulic.
Shayan and tokaldany 2014 studied the effects of upstream blanket and sheet pile on reducing seepage flow exit gradient and uplift force.
It is observed that the best location of sheet pile to reduce seepage flow is at the downstream end.
The 7 saturated unit weight of the soil is 130 pcf and the hydraulic conductivity is 3x10 ft sec.
It is placed at the exit point where the water emerges from the foundation.
The flow net for a sheet pile is shown below.
It con sists of graded sand and gravel.
The sheet pile penetrates 20 feet into the soil.
The exit gradient is then computed as 0 62 divided by 3 3 making the upward gradient 0 19.
A sheet pile cutoff wall simply called cutoff wall is used in almost all types of water retaining structures to reduce the exit gradient at the downstream toe and prevent the chances of sand boiling and piping.