公路隧道喷射型ECC物理力学性能及其喷层稳定性OA北大核心CSTPCD

Traditional fiber-reinforced cementitious composites(ECC)are limited in application due to their high cost and considerable shrinkage.Additionally,research on the stability of sprayable ECC layers in highway tunnels under excavation disturbance remains incomplete,with inad-equate monitoring and evaluation following its engineering applications.This study investigates the physical and mechanical properties of spray-able ECC in highway tunnels.It analyzes the stability of the surrounding rock and the sprayable ECC layer under excavation and evaluates the ap-plication effectiveness through field monitoring.The results indicate that the physical and mechanical properties of sprayable ECC can meet the requirements for shotcrete in highway tunnels by incorporating desulfurized gypsum,hybrid fiber,manufactured sand,an expansion agent,and a shrinkage-reducing agent into the ECC mix.Based on numerical simulations,for a 12-m support,the peak tensile and compressive principal stresses of the sprayable ECC layer increase by 36.8%and 28.4%,respectively,compared to the C25 shotcrete(C25SC)layer.The maximum ver-tical displacement of the inner arch reduces by 3.15%compared to C25SC to only 1.23 mm.Based on on-site monitoring,under the same geolo-gical conditions of the surrounding rock,sprayable ECC minimizes the vertical settlement deformation by 10.26%compared to C25SC.In addi-tion,no cracking or linear seepage is observed on the surface of the sprayable ECC layer.Therefore,sprayable ECC holds broad application pro-spects in highway tunnel support with appropriate modifications.