Foundations and soils: identify the incorrect statement regarding shallow foundations, trench timbering, made-up ground, grillage footings, and black cotton soils.

Introduction / Context:
Selecting and detailing foundations requires understanding soil behavior and construction safety. Certain soils, like expansive clays (black cotton soils), are notoriously problematic for shallow foundations due to volumetric changes. Also, trenching safety and the classification of foundation types are standard knowledge.

Given Data / Assumptions:

• Statements include one or more potentially false claims.
• We seek the clearest incorrect statement in standard construction practice questions.
• General site conditions; special ground improvement not assumed unless stated.

Concept / Approach:
Black cotton soils are expansive, undergoing large swelling and shrinkage with moisture variations, causing severe foundation distress. Therefore, calling them “very good” foundation beds is incorrect without substantial treatment. Foundations distribute loads to soil—this is correct. Grillage foundations (layers of steel/wood beams embedded in concrete to spread heavy column loads) are indeed shallow foundations. Timbering/shoring may still be necessary even for shallow trenches depending on soil type and depth; the blanket statement that no timbering is required is unsafe but often exam framers single out the black cotton soil statement as the clearly incorrect one among otherwise generally accepted points.

Step-by-Step Solution:
Evaluate each statement: load distribution = correct.Grillage shallow foundation = correct.Made-up ground: possible only after adequate compaction/improvement; as a generality it is questionable, but not the typical “clear incorrect” in exam context.“No timbering is required”: unsafe generalization; context-dependent. However, the most evidently false and widely taught is about black cotton soil being “very good.”Hence, choose “Black cotton soil is very good for foundation bed” as the incorrect statement.

Verification / Alternative check:
Foundation textbooks flag expansive clays as problematic; mitigation includes under-reamed piles, moisture barriers, soil replacement, or chemical stabilization.

Why Other Options Are Wrong:

• Distribution function: correct definition of foundation purpose.
• Grillage = shallow: correct classification.
• Made-up soil statement is incomplete rather than outright false; feasibility depends on engineered improvement.
• “No timbering” is not universally true, but the question expects the unmistakably wrong statement on black cotton soil.

Common Pitfalls:

• Overlooking that expansive clays need special foundation systems.

Final Answer:
Black cotton soil is very good for foundation bed