Micro- Tunneling

 Micro- Tunneling 

A . General 1.1 Micro - a tunnel construction method of underground pipes that are not related to the trenching of the soil surface . It involves the excavation using a TBM guided by drilling the computer ( TBM ) and installation of straw tubes controlled remotely . 1.2 Micro Works - tunnel will be undertaken by a specialist subcontractor must be approved by the engineer, who can demonstrate successful experience of similar work in the Gulf region .

1.3 The Contractor shall provide all necessary information for the subcontractor geotechnical specialist.

Be considered 1.4 All references to the Contractor in the following provisions of this section of the specification to include the specialized subcontractor. 1.5 The pipe sections listed in the documents to be built " in the trenches " can be constructed by micro - tunnels, no extra charge , subject to the written approval of the Engineer. The contractor will not be allowed to build any pipe trench reported being built by micro - tunnels.

Two . Survey 2.1 The Contractor shall record the levels of ground before the start of shaft sinking and tunneling work . Points reliable reference and reference stations were established. The locations of these will be agreed with the Engineer. Four reference stations will be established around each axis. Levels will be taken along the line shifts and 5 meters and 10 meters from each side of the tube at intervals of 15 meters between the center axes . 2.2 In case of structures adjacent to the tunnel work the Contractor shall investigate all buildings and structures located within the area of ​​influence is considered a distance in the plane of the center line of the same works the depth reverse this part of the work under the ground level.

 Levels must be taken and recorded on all items above daily intervals during construction of micro - tunnels, another week before issuing a certificate of completion , and finally at the end of the period maintenance. 2.4 survey constructed for each unit micro - tunnel is taken at the end of each unit. The contractor is responsible for the protection of works and adjacent properties. Contractor is responsible for determining what other areas specified above to be recorded by investigating the conditions to satisfy the obligation of the contractor are required. 2.5 The Contractor shall submit a method statement setting and check the alignment of tunnels and shafts for approval by the Engineer before the work begins. Suitable for verification of the investigation and identify opportunities examine the engineer. 2.6 Details of all readings establishing and calculations are kept on site and presented in a clear and orderly manner to allow ease of verification . The Contractor shall provide all the required lines and levels, with all the necessary equipment for the work that will be built to required tolerances . Those who set lines and levels must be carefully preserved, and if replaced for the entire period for which you need.

2.7 The main system used to implement the main supervision of excavation and tunnel lining trees, including the verification and recording of the " building -s - " The position of the lining at regular intervals.