Full-Scale Experimental Investigation On The Bearing Characteristics Of Segment-SCC-Steel Superimposed Lining Structure Subjected To External Pressure

The sustainable use of water resources and the supply of high quality and sufficient raw water are important guarantees for the sustainable development of the economy and society.In order to effectively solve the water contradiction of urban economic development and the long-term imbalance of water resources distribution and discrepancy of water quality,long-distance and inter-basin water transfer through pressuried shield tunnel is a flexible and reliable solution.Focus on the resistance of high internal hydraulic pressure and repeated water hammer impact,and potential benefits of the confining inflation from the surrounding ground,the Segment-SCC-Steel superimposed lining structure is proposed.The trilaminar superimposed lining forms a combined force system to improve the overall bearing capacity and durability of the tunnel structure.However,the domestic and overseas researches on the theories and analytical model about trilaminar superimposed lining structure are still not mature at present.The couple bearing effect between internal and external linings subjected to external loads is ambiguous.The force transmission and load sharing mechanism between the linings are still controversial as well as the adequate experimental argumentation are relatively scarce.Based on the Pearl River Delta Water Resources Allocation Project which is under construction,this paper applies structural system experiment,partial component test and detailed numerical simulation to study the transverse mechanical behavior and deformation characteristics of the specific superimposed lining system of Segment-SCC-Steel.The main work and achievements of this paper are summarized as follows:(1)The 1:1 prototype experimental scheme of large complex lining structure was designed,and the monitoring system for multi-layer lining structure based on distributed optical fiber was established.The full-scale structural experiment of Segment-SCC-Steel superimposed lining system under complex external loads was implemented;(2)Through the full-scale experiment results,the overall deformation and interface relative displacement characteristics of the specific structure under the uneven external loads,the mechanical response of each layer of linings as well as the force transmission pattern were preliminarily investigated.The influences of load change,lateral pressure coefficient,longitudinal difference and stud layout on the transformation and stress of the structural system were discussed;(3)Two steel-concrete composite beam tests were carried out to obtain the Steel-SCC interface performance.Subsequently,two three-dimensional finite element models of steel-concrete components and superimposed lining system,respectively,were established by means of detailed simulation based on the test results of reduced-scale components.The comparison between the numerical calculation and the full-scale experimental results showed that the proposed model could basically reflect the morphological distribution and development process of superimposed lining system.including overall radial deformation and the longitudinal opening of segmental lining,the relative peeling/sliding of the interface,and the circumferential strains of steel pipe and SCC filler.Further,the structural analysis model was used to predict a portion of indicators of the trilaminar superimposed lining system under heavy loads.