Environmental Engineering Reference
In-Depth Information
foundation), the position of the resultant force and the compressive strength factor in
the concrete and foundation. The Sliding Factor (SF) is defined as:
Available Shear Resistance
Net Driving Fo
SF
(16.1)
rce
The net driving force represents the collection of tangential components of all forces
acting above the sliding surface (in the direction considered).
Two states of available shear resistance of concrete and the foundation should be con-
sidered: peak and residual.
The peak shear resistance should be based on the following components:
(a) Normal Stress (Sn) acting on the potential sliding surface;
(b) Peak angle of effective internal friction (
);
(c) Area of compression (Ac);
(d) Threshold shear strength (
o ) at zero normal stress (sometimes called the “cohesion”)
and calculated from:
{
}
Available Peak Shear Resistance
Ac (Sn) tan
(()
(16.2)
o
The residual or post-peak resistance should be based on the following components:
(a) Normal Stress (Sn);
(b) Residual angle of effective sliding friction (
);
(c) Area of compression (Ac);
(d) Nominal residual threshold shear strength value (
nr ) up to 100 kPa if supported by tests.
Without tests,
nr should be considered to be zero and the available residual shear
strength calculated from:
{
}
Available Residual Shear Resistance
Ac (Sn)
tan(
)
(16.3)
nr
The compressive strength factor is given by:
th
maximum compressive stress normal to the assumed failure surface
unconfined compressive streng
compressive
strength factor
(16.4)
The assessment of the stability should also consider observed behaviour and monitoring
data such as ambient and concrete temperatures, plumb line deflections, joint meter
readings, surface monument displacements, foundation piezometric pressures, foundation
and structure drain flows, extensometer readings and strong motion accelerograph
records.
16.2.5
Acceptance criteria
The acceptance criteria given in Tables 16.1 and 16.2 are based on those from CDA
(1999) and BC Hydro (1995). They are considered a reasonable and logical approach.
 
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