Grouting Material or Solution for Post Tensioning of Anchors

I assume the problem is grouting the bottom of the tendon into the rock, is that correct?

All I can think of is to overbore the hole to a short distance below the vent, drive a long pipe, with an inside diameter as large as the original hole, from near the top of the dam, down into the socket you have just drilled, place the tendon, then force the grout down the tube. You will have to make a special anchor point at the top because of the bigger hole.

You will have to go to a concrete supplier and request a special batch of non shrink grout which can be poured and will be able to dry before it gets washed away.

The most important is that the grouting you do before you place water behind the dam, since it will weaken the anchoring.

Hello, perhaps this is the type of post-tensioning grout product you are seeking:

http://www.kingshotcrete.com/Product_Catalogue/products/Grout/MS_Cable_Grout.aspx

Material is highly resistant to ground water. You may have to do a trial injection of the referenced grout material, but my suggestion to you is to first stop the high degree of water flow throughout your anchor area......inject bentonite clay slurry upstream of your anchor area to stem the flow of water.

Are you in a river or stream floodplain or bed? Have you successfully diverted all of the river or stream flow, as well as subsurface water flow, around your rock anchor area? what is the geological makeup of the encountered rock? Is groundwater hydraulic piping conditions present?

Am I correct in assuming that your job site features fractured rock, therefore you have the water flow problems?

Additionally, was any Geotechnical investigation performed at your job site? Does any geotechnical engineering report exist? If not, you had better conduct one before you waste a whole bunch or construction time, money, materials and labor.....

EXACTLY WHAT IS THIS "HORIZONTAL VENT"? Did you guys construct it?

There are too many unknowns and not enough "given" information of design and field conditions to give you a definitive answer and a engineering safe solution tp ypur problem.....I feel very uneasy about this OP....I can envision a dam failure in the future, and the result will be undoubtedly death and destruction. Not a good situation.

Another 3rd world wonder....ohhhh my, the horrors, the horrors.....

the vents were installed to relieve water pressure that may cause up lift

I forgot to include some relevant information for the OPer:

Go to the US Army Corp of Engineer's (USACE) website and download a few of their free Engineering Manuals for starters. Study them and learn, then plan and implement using sound engineering judgement.......

http://140.194.76.129/publications/eng-manuals/

There are 3 good EMs to download for starters. There are others on other USACE sites, including Specifications.

EM-1110-1-2907 "Engineering and Design - Rock Reinforcement".

EM-1110-1-2908 "Engineering and Design - Rock Foundations".

EM-1110-1-2907 "Engineering and Design - Chemical Grouting".

Thanks for all comments.

My question is that grout is not washing away by water but only through the vents. How we will prevent the grout spilling out from Vents. Is there any special grout to be used or any geotextile stuff to seal the hole. what will be methadology for grounting or putting any geotextile membrine in the vent/hole.

thanks

Thanks.

i have run into this myself install rock anchors in dams. the vents were installed to relief water pressure that could casue up lift.

i was sucessfull using a product called "grout Sock" the product is sold by williams form engineering, i used the sock and consolidated grout and redrilled.

good luck