Tunnel construction is now one of the most important jobs which make hard ways easy for passing. Nowadays, tunnel makers are able to introduce tunnel under seas, mountains and basement levels as roads, telephone line and electricity wires, railroad, hideaways, transfer of pipe line, water pipe, etc.
In this case, Parsian Ghaleb Commercial and Industrial group has played its role well by designing and producing lining mold of these tunnels in the state.
Along with tunnel digging by holing, spitfire methods or mechanized method, the excavated place shall be kept by rock belt method. After this primary care, main and permanent wall of tunnel is performed. This wall is constructed by concrete and this operation is called as lining tunnel or internal armature of tunnel. Sections of lining tunnel mold depend on application and type of land in which the tunnel is excavated. Tunnels for water piping are constructed by round or horseshoe sections and road tunnels in fornicated form with flat or horseshoe seat. Oval or semi-oval sections are used for sewage tunnels.
Tunnel molds are divided in two groups in terms of closing and opening: hydraulic and mechanical molds. Mold segments are closed and opened by hydraulic jacks in hydraulic molds and by oily or manual jacks in mechanical molds. Hydraulic system is usually used for great segments and this is due to being segments heavy. Totally, use of hydraulic molds has more executive and economic advantages than mechanical molds. A complete set of tunnel mold includes following elements:
Cart, pod, hydraulic system, vibration system
Connections and its accessories
Considering to development of cities in our country, it is very necessary to construct types of tunnel in the field of urban transportation, water and sewage transfer, metro lines and stations, piping without superficial excavation, underground spaces for electricity production, underground parking spaces, and access to mines. In designing and excavation operation of these structures, lining operation is possible by special mold of tunnel.
Considering to special type of loading in tunnels, use of a primary cover is necessary for primary stability and prevention from landslip and instability of excavated structures. Thickness of this layer has direct relation with excavation method, type of soil or stone, speed of excavation and available facilities. After complete excavation of tunnel and primary lining operation, a long time stability of tunnel is performed by secondary lining. Primary lining operation is usually in form of mesh or wet and dry shot krait and final lining operation may cover a wide spectrum of supports depending on type of soil or stone of the region. Use of tunnel lining mold and armature as a common method for primary and final cover shall be answerable to a long term loading (creeping behavior of stone or soil) and dynamic powers of earthquake.