Experimental Study On The Influence Of Shear Band On Water Migration In The Interface Zone Between Silty Clay-Concrete In Changchun Area

Water migration can change the physical,mechanical and structural stability of soil.In engineering projects involving soil-concrete interface,water migration can cause engineering disasters such as concrete structure leakage,internal steel corrosion and so on.Under external load,soil and structure move relative to each other,forming a binary interface zone from the soil-concrete interface to the outside.The soil structure changes significantly in the interface zone,producing a shear band that changes the permeability of soil,alters the water migration pattern in the original soil within the shear band,and may induce engineering problems such as underground pipe gallery seepage,slope collapse and road slurry.These problems affect the service life and safety performance of engineering structures.Based on these reasons,this thesis takes the interface zone of silty clay and ordinary concrete in Changchun area as an object,studies the influence of shear band at soil-concrete interface zone on water migration pattern with support from National Natural Science Foundation of China(42072296),and conducts following research:(1)Field sampling of bearing layer soil in Changchun area was carried out.The movement rate of soil particles and dry density of soil within shear band were tested by direct shear test of silty clay-concrete binary interface zone,particle image velocimetry(PIV)technology and ring knife method respectively.The variation law of movement rate and dry density with shear displacement was explored.The results showed that with increasing shear displacement,movement rate gradually slowed down until it stabilized after peak shear stress was reached.Meanwhile,the dry density of the soil within the shear band increased first and then slightly decreased,reaching a peak value when the shear stress reached its peak value.(2)Through water migration experiments in soil with shear band,the influence of shear band on water migration in soil was studied under five shear displacements(0,3mm,6 mm,9 mm,and 12 mm),three normal stresses(300 k Pa,400 k Pa,and 500 k Pa),and three initial soil water contents(16.7%,20.7%,and 24.7%).The results showed that the water migration rate in soil with shear band was significantly lower than that in soil without shear band.As the shear displacement of the binary body increased,the migration rate of water in the shear band and the entire soil gradually decreased.After reaching the binary body failure displacement,the water migration rate increased slightly.The distribution of volumetric water content in the entire soil was divided by the shear band.The volumetric water content of the soil below the shear band first increased and then slightly decreased,while that of the soil above the shear band first decreased and then slightly increased.In addition,the water migration rate in the shear band was negatively correlated with the normal stress and initial soil water content.(3)Based on the continuity equation of unsaturated porous media and the generalized Darcy’s law,a differential equation for the migration of soil water under shear was established.The entire process of water migration in the shear zone of unsaturated soil was studied using numerical simulation methods,and the simulation results were in good agreement with the experimental values.This method can obtain the change process of volumetric water content in each layer of soil.This paper focuses on the study of the influence of shear band at the interface between silty clay and concrete on the migration of water,providing a theoretical basis for the variation of water migration in the interface area between silty clay and concrete in Changchun,and also providing a reference basis for the durability design of engineering structures.