alpierce
Civil/Environmental
- Dec 7, 2001
- 1
We have just conducted a gama-ray cement bond log on a well that has begun to show microscopic evidence of surface water contamination after a recent (4.6)earthquake. The test shows that much of the concrete grout below solid rock is missing or significantly weakened. Caliper and video show it entirely missing at the very base of the casing. This is a 170' long 12-inch casing grouted into a 16-inch hole. Solid limestone begins at approximately 100 feet into the hole. A 12-inch bore was continued another 150 feet below the casing.
The gama-ray test shows the concrete to be bonded until the casing goes into rock and at that point the grout is in poor condition to the bottom.
Is this a normal occurance in earthquake prone areas? This installation was done to A100 specifications. Is there a better spec or regulation that has been modifidied to provide some resistance to stress occuring during an earthquake?
The gama-ray test shows the concrete to be bonded until the casing goes into rock and at that point the grout is in poor condition to the bottom.
Is this a normal occurance in earthquake prone areas? This installation was done to A100 specifications. Is there a better spec or regulation that has been modifidied to provide some resistance to stress occuring during an earthquake?