Unsupported browser

For a better experience, please update your browser to its latest version.

Your browser appears to have cookies disabled. For the best experience of this website, please enable cookies in your browser

We'll assume we have your consent to use cookies, for example so you won't need to log in each time you visit our site.
Learn more

Technical paper: Analysis of a dynamic pumping test in an area enclosed by cut-off walls

A Monnet & Y Iagolnitzer, Bachy Paris. This paper was first published in GE’s August 1994 edition.

Introduction

Two construction techniques have evolved for buildings with deep basements under a phreatic water level:

  • the construction of an impermeable concrete raft at the base of a structure. This approach applies as long as the building load can withstand the water uplift pressure, and where the sub-soil is pumpable, without disturbance, during the temporary stage when the base of the excavation has been reached but the raft is not yet constructed; and
  • the creation of an area enclosed by side walls (usually diaphragm walls), and a grouted raft or a geological soil layer having a low permeability. Pumping rates are thus considerably reduced, but the need for pumping is permanent. This solution is chosen in cases where the first is technically not feasible, and also when permanent pumping proves more economical than a raft (for example, with very light structures).

It is the development of the latter concept that created the need for a new pumping test which, because permanent pumping has a cost (drainage layer, pumps, maintenance, etc.), makes it necessary for the client to know, prior to any excavation, what the pumping rate will be in the long term. 

Have your say

You must sign in to make a comment

Please remember that the submission of any material is governed by our Terms and Conditions and by submitting material you confirm your agreement to these Terms and Conditions. Links may be included in your comments but HTML is not permitted.