G-4 E-1

Examples:

1.In a constant head permeability test with a cross section area of 10cm² when the flow was taking place under the hydraulic gradient 0.5 , the amount of water collected in 60 sec. is 600 cc. permeability of soil “k” is?

Ans:

In Constant head permeability

                             Q=K.i.A

                       

                       hence

                            

                     

                                    K = 2 cm/sec

                             

2. In a falling head permeability test the initial head of 0.1 m dropped to 0.35m in 3 hours and the diameter Of the stand pipe being 5mm. The specimen was 200mm long and 100 mm diameter. The coefficient of permeability of soil is  ?

Ans:

                    Falling head permeability test       

Area of stand pipe(a)             =  pie/4 * 5²   = 19.625 = 0.19625 cm²

Length of specimen(L)          = 200 mm                       =20 cm

Area of specimen(A)              =  pie/4 * 100² = 7850  = 78.5 cm²

Time taken for head drop(t) =3 hours                           = 10800sec     

                         Hence                                  

                                                     

                                           

           K= 4.86x10^-6 cm/sec