Repairing Spillway Damage at Wanapum Dam

摘要

The spillway has performed in accordance with the design based on daily visual inspections, field surveys, foundation piezometer measurements, Monolith 4 upstream crack meters, lift joint drain flow monitoring and spillway gallery weir flow readings. Important take-aways of the remediation project are: 1. Operations personnel are important links to discovery of PFMs and can help arrest dam safety incidents. A district hydro mechanic discovered and reported unusual manifestations of monolith movement. 2. Thermal forces exist in the spillway, which cause significant tensile stresses at the upstream face during the winter - stresses that weren't typically incorporated in 1960 stability analyses. 3. FEA was able to incorporate thermal, tensile stresses; determine post-tensioned anchor requirements to satisfy stability criteria; and minimize seismically induced downstream displacements. 4. Installation of the maintenance bulkhead causes eccentric, critical loading. 5. Installation of lift joint drains reduces hydrostatic pressure within the monolith and provides a means of monitoring monolith condition by measuring flow volume.