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Re: cut and cover
Author: Ed Workman
Date: 01-26-2017 - 11:21
Gosh
Sure looks like cut and cover to me, a lot like Market St.
The large and multi-story stations on market st were not amenable to tunneling, and two levels of tunnels in the short sections between stations were problematic if built as tubes.
If anything, the cut and cover[just like Mkt St] of the Central SubWay should be easier- looks like actual dirt being excavated under the roof, rather than the gooey bay mud of lower Market
The bay mud provided some large challenges for shoring the excavation. As the mud was removed below the bracing, and until there was room to get another layer of bracing installed [at a level that would not conflict with a roof or floor slab] The soft mud allowed the {100++ foot] shoring piles to deflect- That deflection had to be controlled by very stiff piles, and monitored,
cuz the movement of mud into the deflected shape could cause adjacent building foundations.
So I hope I live long enough to read the answer to the TransBay Terminal problems
I sure enjoyed the sound of the STEAM pile drivers on MArket as I crossed on my way from the bus to PBQ&D offices
Sure looks like cut and cover to me, a lot like Market St.
The large and multi-story stations on market st were not amenable to tunneling, and two levels of tunnels in the short sections between stations were problematic if built as tubes.
If anything, the cut and cover[just like Mkt St] of the Central SubWay should be easier- looks like actual dirt being excavated under the roof, rather than the gooey bay mud of lower Market
The bay mud provided some large challenges for shoring the excavation. As the mud was removed below the bracing, and until there was room to get another layer of bracing installed [at a level that would not conflict with a roof or floor slab] The soft mud allowed the {100++ foot] shoring piles to deflect- That deflection had to be controlled by very stiff piles, and monitored,
cuz the movement of mud into the deflected shape could cause adjacent building foundations.
So I hope I live long enough to read the answer to the TransBay Terminal problems
I sure enjoyed the sound of the STEAM pile drivers on MArket as I crossed on my way from the bus to PBQ&D offices
