G S Littlejohn, BSc,PhD, CEng, MICE, MIStructE, FGS. This paper was first published in GE’s March 1975 edition.
On completion of drilling, the anchor borehole must be tested for “water tightness”. The purpose of this technical note is to assess reasonable threshold values for water loss or gain which, when exceeded, dictate the need for waterproofing.
Bearing in mind that loss of grout from around the cable in the fixed anchor zone is of prime importance in relation to efficient distribution of load and corrosion protection, the minimum width of fissure which will permit Row of cement at low pressure must be assessed.
lf a hole fully intersects a fissure the fluid loss or gain may be calculated using an equation of the form indicated by Baker (1955).