Correct Answer - Option 2 : 18
Explanation:
Bligh's Creep theory:
(i) This theory is base on the assumption that seeping water through the soil below the weir.
(ii) Follows the path along with the contact of the base, with the underlying sub-soil.
(iii) The length of the path of seeping water from the point of entry into the sub-soil from the U/S of the impervious.
(iv) Apron to the point at the D/S end of the impervious apron is know creep length.
(v) Bligh also assumed that loss of head of the seeping water is proportional to the length of its travel irrespective of whether.
(vi) If H is the total head causing seepage or total loss of head, and L the total creep length, the loss of head per unit length of creep (C) is given by
C = H/L
Where C is the Blighs Creep Coefficient
Safe values of coefficient of creep for different soils are given below:
| Types of soil |
Coefficient of creep |
| Sand mixed with boulder and gravel and for loam soil |
5 to 9 |
| Coarse-grained sand as found in south and central Indian river |
12 |
| Coarse-grained sand as found in northern Indian river |
15 |
| Light sand and mud |
18 |
