Design approach for major canal structures on pervious foundations — which analytical method is generally preferred for weirs/barrages and similar works?

Introduction / Context:
Hydraulic structures founded on pervious soils (e.g., river alluvium) require assessment of seepage pressures and exit gradients to avoid piping and uplift failures. Over time, methods evolved from empirical creep theories to more rigorous potential flow solutions. This question tests knowledge of the commonly preferred analysis for major works.

Given Data / Assumptions:

• Major hydraulic structures (weirs, barrages, regulators) on pervious foundations.
• Need to evaluate uplift pressures, exit gradients, and cut-off requirements.
• Established design methods are being compared.

Concept / Approach:

Khosla's method of independent variables is based on potential flow theory and uses elementary solutions superposed for piles, floors, and sheet piles to calculate pressure distribution more accurately than early creep theories. Consequently, it is preferred for important structures where rigorous assessment is necessary.

Step-by-Step Solution:

Verification / Alternative check (if short method exists):

Compare with Bligh/Lane → primarily empirical. Khosla → analytical potential flow solution giving better reliability for design.

Why Other Options Are Wrong:

Empirical methods are less rigorous; electrical analogy/relaxation are tools to solve Laplace's equation but not the commonly cited design framework for canal weirs in practice questions.

Common Pitfalls (misconceptions, mistakes):

Assuming Bligh's theory suffices for major barrages without safety checks; overlooking exit gradient control.

Final Answer:

Khosla's method of independent variables