Used for vertical underground access McAllister Specialist Construction can construct a Segmental Cassion shaft from the surface directly on top of the pipe. McAllister Specialist Construction can shaft sink in a number of various ways , dependent on the ground conditions. In hard ground or rock the shaft can be constructed using an underpinning method and the segments grouted in place as each ring is constructed. McAllister Specialist construction can also sink or hydraulically jack the shaft through the strata with a cutting shoe unto the asset or close enough to expose and provide structural support before gaining access.
Specialist sewer or pipeline access
Getting access to the underground asset can be difficult, things can be above on the surface blocking direct access. Even locating the structure from the Surface can be a challenge, McAllister specialist construction can assist in remote survey location of the underground assets through a number of different survey methods.
Once located the asset or pipe has been located the next step is to get access to it. At McAllister Specialist Construction we have a number of various ways that we can assist;
Primarily used for horizontal access to the underground asset. When vertical access from the surface is not possible, often a shaft is sunk to get to the same level as the asset below ground and then a pipejack or timber heading installed to reach the asset. Dependent on the ground conditions a suitable jacking pipe (either reinforced concrete or GRP) can be hydraulically jacked into position through carefully controlled excavation at the tunnel face.
A more traditional hand mining technique when the ground is suitable, a timber frame can be used to support the existing ground and as the heading advances the heading is grouted in place. This is commonly used in geology such as London clay due to its properties. Often the hand mining technique can allow for greater accuracy when working close to critical sub-surface infrastructure.