Composite shield is characterized by self - driving and cast in site reinforcedconcretelining instead of segmental lining.
组合式盾构的特点是能自行推进，可不用装配式衬砌管片，而采用现浇钢筋混凝土衬砌。
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In recent years the reinforcedconcrete precast element linings are adopted more and more for the soft surrounding rock tunnels. But a perfect assembling method for lining is not performed yet.
The polypropylene fiber reinforcedconcrete, which is a new type of the tunnel lining structure, has the characteristic of easy construction and can improve the concrete behavior and durability.