BRIDGE 12 - STANWAY VIADUCT – KING-POST GROUND STABILISATION PROJECT – work completed.
Following the completion of the new King-post sleeper walls, the old sleeper walls were removed.
This left the north end more or less completed, as in these two pictures.
|Steels concreted in.|
|Steels in place|
The south end proved to be a bit more problematical because of the gabion baskets on the upside, close to which were two signal cables. This did not leave much room to feed the 450mm diam auger between the two but it got done with slight disruption to the back of the gabion baskets. On the downside things were slightly easier.
Once the steel columns were concreted in the concrete sleepers were dropped in on both sides, then the tie bar installation was started.
This involved trenching between the sleepers.
The tie bars are to there to anchor the tops together, which enabled a shorter length for the steel posts to be used. Without the tie bars the resistance to the outward movement of the track bed fill and ballast would be entirely provided by sidewards ground resistance against the concrete casings to the steel posts.
To simplify the installation, the tie bars were in 3 pieces with couplings to fasten them together.
One of the problems encountered in one section, was where cement grout had been mixed with the ballast to create a large concrete lump which had to be broken out to allow the trench to be dug.
After the tie bars had been tightened up the side trenches were filled to restore the ballast levels back to the original and the ground outside the new walls could be regraded.
At the north end, the difference between the track level and the original ground was greater, as can be seen from the step down from inside to out. There was limited scope for levelling there.
The final task was to try to locate the Inspection chambers for the viaduct drainage. Unfortunately, by installing the track down the centre of the viaduct, they were all buried preventing any maintenance.
With no real details of where they were we dug down to find one.
Finally, the above two photographs show the completed stabilisation works.
Photos courtesy of Alastair Watson, John Balderstone & Peter Muir.
8.3.2019 - JOHN BALDERSTONE