A Study Of An Acrylate-based Sprayed Membrane For Waterproofing Of Composite Shell Lining Tunnels

With the rapid development of tunnel engineering in China,the problem of water leakage has become increasingly prominent,and it has become a key factor restricting the durability of tunnels.The introduction of sprayed acrylate waterproofing membrane has led to the innovation of CSL(Composite Shell Linings),comprising of a permanent sprayed primary lining,a double-bonded(i.e.with a assured bond to both primary and secondary layers)sprayed waterproofing membrane,and a sprayed secondary lining.This configuration tends to solve the serious water leakage issue of sprayed concrete,effectively reduce the thickness of the linings and reduce engineering costs.This thesis investigates the behaviour of CSL based on an acrylate membrane for waterproofing,including bonding strength,waterproofing performance,and mechanical performance,via laboratory experimental work,theoretical analysis,and numerical modelling.It can provide support for the promotion and application of CSL.The main research and findings can be summarized as follows:(1)The factors of influencing tensile bond performance were assessed systematically via3 D profilometry,image processing,and scanning electronic microscope.The roughness of sprayed concrete is quantified using fractal dimension.For the tensile bond performance between the primary sprayed concrete layer and the waterproof membrane,the effect of substrate roughness,water content,and membrane thickness was confirmed.For the tensile bond performance between primary and secondary sprayed concrete layers isolated by the membrane,the effect of membrane thickness and long term behaviour exposure to groundwater were confirmed.(2)A corrosion-resistant penetration device was developed,and the durability of sprayed acrylate waterproofing membrane was examined through this device taking into account the different groundwater and spraying distances.At the same time,the surface condition and microstructure of the waterproof membrane were analyzed with the help of SEM and CT technology.The influence of different groundwater and spraying distances on the mechanical properties of the membrane(tensile strength,elongation at break and tearing strength)was obtained,and the microscopic mechanism of the influence was explored.(3)Based on the pseudoelasticity behaviour of the waterproof membrane,the shear mechanics property between sprayed concrete and membrane was studied by means of numerical analysis.The influence of interface roughness and membrane thickness on its shear strength and failure morphology were explored.(4)Numerical analysis and capacity evaluation of composite sprayed concrete lined tunnels were studied.The effects of interface parameters and membrane thickness on the deformation characteristics and mechanical behaviour were obtained.Load sharing in sprayed concrete linings isolated by the waterproof membrane was confirmed.