Geotechnical Engineering Mathalino File

"Stone columns require from the surrounding soil," Mai countered, her voice steady now. "Your soil has an undrained shear strength ((c_u)) of only 15 kPa. The stone will punch through it. That's not reinforcement; that's a hammer falling through a wet paper bag." Part IV: The Third Decimal Silence. Mang Lito poured a cup of sweet coffee and placed it in front of Mai.

She flipped her yellow pad. "Look at the (FS). For highway embankments, FS must be 1.5 against bearing failure. Right now, FS = (q_ult/q_allowable) = 120/200 = 0.6. That is not an FS. That is a recipe for a sinkhole." geotechnical engineering mathalino

The client stared at the equation. "That number. The '8' in the numerator. Why 8?" "Stone columns require from the surrounding soil," Mai

She drew the by Hansbo:

"You cannot change the friction angle ((\phi)) of the native soil without replacing it. But you can increase the normal stress ((\sigma)) by surcharging. Or you can add cohesion ((c)) via grouting." That's not reinforcement; that's a hammer falling through

This story is inspired by the thousands of Filipino engineers who use to master the math behind the mud.