Depressurization Probes in London Clay

[salam0506]

Hi Guys,

Am currently working on a tunnelling project in london and we are about to do some depressurization probes and I was hoping someone might have some more info on what this entails and the background science on it.

Any books or resources anyone can suggest?

Cheers
Seenan

 

[cvg]

depressurization probes = dewatering wells? or piezometers? or well points? or?

 

[salam0506]

I am under the impression they are dewatering wells - we are looking to reach the lambeth group under the london clay which is going from very stiff clays to fine sand - I am assuming to prove there is no water or check if there is... do you know of any theory papers or background I could read up on?

 

[cvg]

first, find out exactly what your scope of work / problem / area of research is. then maybe somebody could steer you in the correct direction. For general information, the USBR Engineering Geology Field Manual and the USBR groundwater manual might be useful

 

[salam0506]

Well we have completed a pilot tunnel and now we are undertaking a series of boreholes drilled at angles from 43 to 60 degrees at the entrance of the pilot tunnel in the direction of the tunnel as part of the "strategy for depressurisations and incestigations SCL tunnels" to check if groundwater is encountered. "The depressurisation is required over the cover depth of clay for the given tunnel to prevent instability due to uplift and this probing lenths are determined from this" - I am not entired sure what this means and how it related to the tunnel?

 

[racookpe1978]

Come on.

Talk to your boss, to the senior tunneling engineer:

"What do you need from these holes, and where have you seen problems before?"
"What should I be looking for?"- your earlier post CONFIRMED you were new to the job of tunneling and boring in clay!
"When do you need a call from me IMMEDIATELY on the backshift, and what can I do better to keep you informed on this shift?"
"What problems do you not expect that I should anticipate?"