Design Summary on Unbonded Pre-stressed Concrete Liner for Sediment Tunnels of Xiaolangdi Project
TIAN Yu-pu, ZHANG Xiao-rui, DING Yi (Reconnaissance Planning Design and Research Institute, YRCC, MWR, Zhengzhou 450003, China)
The sediment tunnel of Xiaolangdi project with the applied head of 122m undertakes the task of sand and flood discharge from the reservoir. For preventing the liner from cracking and the consequential leakage, which will hazard the stability of the mountain, it is planned to use cohesive pre-stressed concrete liner in the original design scheme. However, argumentation of experts based on site testing during construction leads to the replacing of original scheme by unbonded pre-stressed concrete liner. This paper presents the structural layout of liner, characteristics of stress in pre-stressed concrete structure, argumentation on and selection of the parameters of the pre-stressed concrete elements and the stretching equipment, etc.