Default criteria

The limits every check is held to by default, tool by tool: factors of safety, the middle third, settlement and bank-full capacity.

Every check compares a value with a limit. These are Rischio’s defaults. Each result shows its margin to the limit, and the check with the smallest margin governs the model.

Retaining walls

Check	Rule	Limit
Overturning The wall rotating about its toe $FS = \frac{\Sigma M_R}{\Sigma M_O}$	$FS = \frac{\Sigma M_R}{\Sigma M_O}$	$\ge 2.0$
Sliding The wall pushed along its base $FS = \frac{R}{\Sigma H}$	$FS = \frac{R}{\Sigma H}$	$\ge 1.5$
Bearing capacity The ground under the base giving way $FS = \frac{q_u}{q_{max}}$	$FS = \frac{q_u}{q_{max}}$	$\ge 3.0$
Eccentricity The resultant inside the middle third of the base $e$	$e$	$\le \frac{B}{6}$
Gabion levels Each level overturning or sliding on the one below $FS = \frac{\Sigma M_R}{\Sigma M_O},\; \frac{R}{\Sigma H}$	$FS = \frac{\Sigma M_R}{\Sigma M_O},\; \frac{R}{\Sigma H}$	$\ge 2.0,\; \ge 1.5$

Footings

Check	Rule	Limit
Bearing capacity The ground under the footing giving way $FS = \frac{q_u}{q_{max}}$	$FS = \frac{q_u}{q_{max}}$	$\ge 3.0$
Eccentricity along the width The load inside the middle third, across the width $e_B$	$e_B$	$\le \frac{B}{6}$
Eccentricity along the length The load inside the middle third, along the length $e_L$	$e_L$	$\le \frac{L}{6}$
Settlement The footing's elastic settlement, at its centre $S_e$	$S_e$	$\le 25 \text{ mm}$

Piles

Check	Rule	Limit
Pile group The group's axial capacity, as piles or as one block $FS = \frac{Q_g}{Q}$	$FS = \frac{Q_g}{Q}$	$\ge 3.0$
Single pile One pile's axial capacity against its load, when there's only one $FS = \frac{Q_u}{Q}$	$FS = \frac{Q_u}{Q}$	$\ge 3.0$

Check

Limit

Pile group

The group's axial capacity, as piles or as one block

$FS = \frac{Q_g}{Q}$

\ge 3.0

Single pile

One pile's axial capacity against its load, when there's only one

$FS = \frac{Q_u}{Q}$

\ge 3.0

Open channels

Check	Rule	Limit
Bank-full capacity The discharge fits below the lower bank $Q$	$Q$	$\le Q_{bank}$

Check

Limit

Bank-full capacity

The discharge fits below the lower bank

$Q$

\le Q_{bank}