Muenchen 1

Trench Shoring - Linear Shoring

LINEAR SHORING IN USE FOR MAJOR MUNICH PROJECT

Liner construction used in major munich project - not to be outdone in terms of performance.

In order to relieve the existing sewer system in the area of Pasing and Laim, a new 2.2 kilometer long DN 3000 sewer was excavated in Landsberger Straße by Wayss & Freytag Ingenieurbau AG - Tunnel Construction Division on behalf of Munich's municipal drainage system using the pipe jacking method. After completion of the jacking work, 19 manholes and three transfer structures were constructed. These provide the connection between the existing sewer and the new sewer. For securing the excavation pits, the contractor opted for E+S Linear Shoring - a slide-rail system with support frame - which was able to meet all the requirements on site, mainly due to its technological performance parameters.

Sensible alternative

In contrast to pile driving or vibration - for example, when sheet piles are used - the construction environment is subjected to much less vibration when linear shoring is installed. In vertically installed double slide rails, inner and outer shoring panels are held in such a way that they slide past each other and can be brought to the required depth. Two flexurally rigid carriages, adjustable in height according to the advancing construction depth, keep the girders and shoring panels at the same distance apart at all times; the trench width remains the same in every construction phase.

Stepped in the truest sense of the word

In the longitudinal direction of the new sewer, the elements of the shoring system could be installed on the side facing away from the pipe using 9.13-meter-long girders up to the bottom of the excavation. On the other side, the 7.13 meter long girders and the shoring panel ended directly on the jacking pipe - as did the shoring on the head ends, which could also only be installed as far as the pipe crown of the jacking pipes. In order to secure the remaining working space, the approx. 2.70 meter high area next to the pipe string up to the bottom, the construction partners decided to install sheet piles behind the shoring on the head side up to the pipe and next to it up to the bottom. In order to secure this structure in accordance with the structural requirements, two head shoring adapters were integrated into the linear shoring system in addition to the two roller units. Like the roller units, the head shoring adapters are guided in the profile of the linear shoring soldiers, can be adjusted in height at any time and are flush with the head edge of the shoring system. A temporary support between the pipe and the lateral shoring wall secured the sheet piles during this construction phase. It could be removed again after concreting a 25-centimeter-thick clean layer.
After pipe jacking was completed, the access shafts and transfer structures were built at a depth of around nine meters.
An advantage especially in inner-city areas: With linear shoring, the ground outside the trench remains largely untouched, and buildings and traffic flow are not impaired. With stepped linear shoring, these advantages can also be exploited for work at greater depths.
When the shoring is installed, the shoring elements are placed in the excavation pit and gradually pressed into the ground by the excavator while the soil is being excavated at the same time.
In linear shoring, the opposing rails are not connected to each other by articulated spreaders, but are kept at the desired distance by a flexurally rigid carriage whose width can be varied.
Four by four meters in size and around nine meters deep: Flexurally stiff roller units that can be adjusted in height according to the advancing construction depth keep the beams and shoring panels of the linear shoring system at the same distance apart at all times; the width of the excavation pit remains the same in every construction phase.

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