Seepage theory | Bligh's Creep Theory | Irrigation engineering

THEORIES OFSEEPAGE * Whenever a hydraulic structure is founded on a pervious foundation, it is subjected to seepage of water beneath the structure, which may cause the failure either by 1. piping 2. direct uplift * According to Bligh’s Theory (i) The percolating water follows the outline of the base of the foundation of the hydraulic structure. (ii) Safety against piping can be ensured by providing sufficient creep length. (iii) The water standing on upstream floor counterbalances the uplift caused by the same water, and hence, only a nominal floor thickness is required on the upstream side. * Lane’s weighted creep theory stipulated that the horizontal creep is less effective in reducing uplift than the vertical creep. He suggested a weightage factor of 1/3 for the horizontal creep as against 1 for vertical creep. However, since it is only empirical formula without any rational basis, it is generally not adopted in any rotational basis, it is generally not adopted in any design. * Acco...