S e c t i o n 1 3 - P a g e 1 2 May 2013 General Specications The following paragraphs ar e of fer ed as a guide for those who write and issue specifcations for steel liner plates as under gr ound supports. Scope These specifcations a re intended to cover the fabrication and installation of liner plates in tunnels constructed by conventional methods. T unnels excavated by full face, heading and bench, or multiple drift pr ocedur es ar e consider ed conventional methods. Liner plates used with any construction method utilizing a full or partial shield, a tunneling machine, or other equipment which will exert a for ce upon the liner plates to pr opel, steer , or stabilize the equipment ar e consider ed special cases and a re not cover ed by these specifcations. Description Cold-formed steel liner plates conforming to the specifcations below shall be fur nished to the sizes and dimensions r equir ed on the plans. Such plates shall be installed at the locations designated on the plans or as designed by the engineer or the r esponsible authority . Design and shape of the liner plates shall be such that er ection and assembly of the liner plate structur e can be completely and r eadily er ected fr om inside the tunnel. Plates shall be accurately curved to suit the tunnel cr oss section, and all dimensions ar e of such size and accuracy that plates of similar curvatur e will be inter changeable. Bolts on both the longitudinal and cir cumfer ential joints shall connect all plates. Gr out holes 2" in diameter shall be pr ovided, as shown on the plans, to permit gr outing as the er ection of tunnel liner plates pr oceeds. Material Specications Thickness tolerances shall conform to AASHTO specifcation for Highway Bridges, Section 16, or comparable AREMA Manual for Railway Engineering, Chapter 1, Section 4~15. The T unnel Liner Plates shall be fabricated fr om structural quality , hot r olled, carbon steel sheets or plates conforming to the specifcation of ASTM designation A1011. The mechanical pr operties of the at plate and sheets befor e cold forming shall be: T ensile Str ength psi 42,000 Min. Y ield Str ength psi 28,000 Min. Elongation in 2", 30 Min. Forming and Punching of Liner Plates All plates shall be formed fr om one piece of metal to pr ovide longitudinal and cir cumfer ential anges. They shall be punched for bolting on both longitudinal and cir cumfer ential anges in accor dance with the manufactur er's standar d spacing, and shall be a multiple of the plate length so that plates having the same curvatur e shall be inter changeable and will permit staggering of the joints. Gr out holes with plugs shall be pr ovided at spacing suf fcient to allow flling of all voids with gr outing material. continued Steel 4-Flange Liner Plates continued www .dsiundergr ound.com