Environmental Engineering Reference
In-Depth Information
Figure 16.18.
Sliding friction shear strength of concrete with lift joints - all USA dams data, split at
750 kPa (Khabbaz and Fell, 1999).
Figure 16.19.
Peak shear strength of concrete-foundation contact - all USA dams data (Khabhaz and
Fell, 1999).
Provided good construction practice has been followed, there is no reason the contact
strength should control. Rather it should be the lower of the concrete strength or the rock
foundation shear strength. However, some existing dams could have had inadequate exca-
vation and preparation of the foundation surface. Potentially unfavourable conditions
that may exist include weathered or blast-damaged rock, consolidation and/or slush grout
at the base of the concrete or a deteriorated contact. In these cases the contact strength
may control, and any extensive areas of weak contact material should be sampled and the
strength determined in the laboratory.
The tensile strength of the contact should be assumed to be zero - because it is con-
trolled by the tensile strength of the rock mass immediately below the contact.
