Most areas on site are not particularly sensitive to lowering ground water levels. The excavation in these areas
will be retained with horizontal timber poles lodged between steel posts (referred to as king posts).
The ground between the Carillon and the Tasman Gardens Apartments is sensitive to settlement through loss of ground
water pressure, so in this area sheet piles will be used. Interlocking steel sheets (sheet piles) form a barrier to ground water loss. The sheet piles will be installed prior to excavation for construction of the underpass.
Working around the sewer
The sheet wall will be 40m long before it reaches the Tory Street Interceptor Sewer.
- The sheet wall will be 40m long before it reaches the Tory Street
- The sewer is an egg-shaped brick structure which is more than
100 years old and is 8m below ground.
- Monitoring equipment will be installed in the sewer manhole to
measure any effects on the sewer.
This article comes from mch edit released
This project involved Pressure Grouting with a Cement / Flyash grout material. The foundation construction of a new cooling tower for a Nuclear Power Plant posed many unique foundation challenges.
Three Sheet Pile Cofferdams were installed to permit excavations up to twenty feet below grade. Two Cofferdams used Tremie Seals to prevent the inflow of water from the bottom. In order to seal the interlocks of the sheet piling to prevent groundwater leakage, and increase the skin friction of the piling to reduce uplift potential, grouting was used.
A Grout Plug was installed on the third cofferdam in lieu of a tremie seal. This Cofferdam, unlike the others, had reasonably sound bedrock at the bottom of the proposed excavation. Steel Casing was installed through the overburden and the rock was drilled to design depth.
Packers were set to isolate the location of the Grout Plug beneath the proposed excavation. Grout was injected into the limerock to fill voids and water courses. Secondary grout holes were installed in areas with larger than normal grout takes. The Grout Plug proved to be a cost effective alternative to a conventional Tremie Seal.
This article comes from earthtech edit released