Research And Development Of High Performance Self-compacting Concrete Material For Filling Layer Of Composite Lining Of Water Conveyance Tunnel

Composite lining structure is a new type of underground tunnel engineering structure.It combines steel lining and segment,and casts high-performance self-compacting concrete material between steel lining and prefabricated segment to form an integrated lining of composite force.structure.Among them,the working performance and durability of self-compacting concrete are the key to the combined structure’s ability to jointly stress,maintain long-term good bearing capacity,and deformation and cracking performance.Relying on the background of the Pearl River Delta water resources allocation project,this paper develops high-performance self-compacting concrete suitable for composite lining structures and conducts relevant tests on its mechanical properties and durability.The following research efforts are mainly:1.Investigated the construction conditions,structural forms,load conditions,service environment,etc.of the composite lining structure to determine the required working performance of the high-performance self-compacting concrete material.According to the characteristics of the raw materials for the field construction,the pure rheological theory mix ratio design method was used.The high-performance self-compacting concrete mix ratio test prepared high-performance self-compacting concrete that satisfies the working performance and strength requirements.Through the compressive strength tests of concrete at different ages,the development law of its strength with the content of fly ash was analyzed and returned.2.The infiltration crystalline spraying material was selected as the binder to enhance the mechanical properties of the bonding interface between the lining segment and the self-compacting concrete.The interface between the new and the old concrete was analyzed by the split-tension test and the shear test of the new and old concrete bonding interface.Effects of bond failure morphology and mechanical properties.3.Using fly ash content as a variable,study the early age shrinkage and cracking performance of high-performance self-compacting concrete specimens under different formulation ratios.Based on the test results,analyze and summarize the early age shrinkage-cracking performance of high-performance self-compacting concrete.Based on the BP neural network,a prediction model of early age shrinkage rate was established and the prediction analysis was performed,which provided a reference for the study of the prediction model of shrinkage performance of self-compacting concrete.