Segmental Tunnel
Segmental Tunnel
(OP)
Hi all, I am doing research on the construction method of laying 900mm and 600mm pipe underground by segmental tunnel (maybe referred to hand dig tunnel) which is 2m x 2m x 30m tunnel at 6m depth (invert level). could you let me have your view on which main components should be considered when designing the tunnel? any reference could be made to? grade I rock stratum is encountered at the depth of 2m.





RE: Segmental Tunnel
Refer to the following links:
ftp://ftp.odot.state.or.us/techserv/geo-environmen...
http://library.modot.mo.gov/RDT/reports/Ri02003/or...
RE: Segmental Tunnel
RE: Segmental Tunnel
RE: Segmental Tunnel
to miningman, your concern is understood. given to the above mentioned situation,there is no alternative but hand dug tunnel is likely.
to buggar, cut and cover construction is unlikely due to the site constraint of my concern.
Therefore, I want to make reference to the past experience for drafting my research and to ask what should I have to care about on the design before carrying out the tunnel works. for instance, where are the loadings applied? what is the appropriate safety factor that should be applied?
please let me have all your views. thanks
RE: Segmental Tunnel
RE: Segmental Tunnel
One of the problems that you will encounter is how to make the connection for the service drop for each individual water user. You will have to install another pit to make the connection.
If you are really in the middle of a major city, you would be looking at some type of auger or jacking.
RE: Segmental Tunnel
Richard A. Cornelius, P.E.
WWW.amlinereast.com
RE: Segmental Tunnel
RE: Segmental Tunnel
Richard A. Cornelius, P.E.
WWW.amlinereast.com
RE: Segmental Tunnel
Richard A. Cornelius, P.E.
WWW.amlinereast.com
RE: Segmental Tunnel
However your pits are simply too small to be on any use, either to build the tunnel in the first place or insert any pipes in them afterwards. you need one to be at least 5-6m long. If you can't get this, then the technique is not feasible IMHO.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Segmental Tunnel
hi littleInch, thanks for your hints.
RE: Segmental Tunnel
a square tunnel is possible but probably not feasible, a round steel casing with a carrier pipe inside is a much better design.
main issues to address:
groundwater and dewatering if necessary
affect of water level or lowering of water level on stability of the face and pit walls
existing trenches / utility lines above the tunnel
leaking sewer lines above
allowable settlement so as to not affect everything above
rock, cobbles, boulders and sand or other layers crossed besides just the clay
shoring of jacking and receiving pits
length of jack / cohesion of material / calculation of the jacking force
determine the allowable length between jacking, intermediate stations and receiving pits
design of the foundation and thrust wall for the hydraulic jack
earth load on the pipe
jacking force on the pipe
design of thrust ring
need for mud or grout?
earth load on the jacking shield
what type of shield
slope stability at the face of excavation
removal of material, slurry pipeline, auger, buggies, buckets
curved or straight alignment, tolerance on line and grade