Permeation Mechanism And Impermeability Of The Connection Stubble Of Plate–Expansive Concrete Contact Surface Of Shaft Lining

The new type of monolayer shaft lining is with broad application prospects．In order todevelop the technology of the new type of monolayer shaft lining, the paper carries out theresearch on the penetration mechanism and impermeability of the steel–concrete contact surfacethrough the methods of physical test, microscopic morphology, numerical calculation andsimulation test．Firstly, the sample simulation is applied to study the effect of proportions of expansivecontent on internal swelling strain and expansion stress of concrete．Then, through the design ofhigh pressure osmotic equipment based on the seepage frontal resistance test method, theimpermeability between concrete and steel wall department is researched. As can be shown bythe results, in case the concrete does not rupture, the higher the normal stress of the contactsurface is, the better the impermeability will be．When the normal stress is lower than0.6MPa,we finally access to the basic law of the contact surface of the seepage when the pressure islower than3.5MPa, and the average seepage velocity will be about3.09×10-5m/s; and when thepressure is4MPa, the seepage velocity will be about1.74×10-4m/s.Secondly, the steel plate-concrete contact surface and internal concrete are observed byusing scanning electron microscope, the result of which shows that there are lots of microscopicholes and cracks in both the contact surface and internal concrete, so does the interface of theaggregate and hydration products. The permeation mechanism of the contact surface is that it canform the seepage channels through the interpenetrated micor-holes and micro-cracks. Joiningexpanding agent in concrete can significantly reduce the holes and cracks in both the number andsize of the contact surface, which can enhance the impermeability of the contact surface.Thirdly, numerical simulation methods are applied to study the seepage condition of thetransition layer of the steel and concrete contact surface, in order to analyze the impact of voidsand aggregate on concrete seepage field. Fluid deflection occurs at the hole, but flow will existaround the aggregate. Both of these two phenomena will lead to the uneven distribution of theflow field inside the concrete, especially in the junction of the holes and aggregate, resulting inthe flow field disorders because of the combined effect of the deflection and flow field.Regardless of holes or aggregates, their influence on the overall scope of the flow field isapproximately doubled diameter of the average range. The calculating results show that underthe pressure of6MPa, the steady flow field flow velocity of the interfacial transition zone isabout5.0×10-10m/s.Finally, through the concrete jointing physical simulation test, the influence of steel platewith concrete jointing shapes of “” and “” on the permeability and mechanical behavior ofthe wall is mainly emphasized. The results show that, in condition that the vertical stress is7MPa, the penetration pressure of the “” shape can reach8MPa; and when the vertical stress is10MPa,the penetration pressure of the “” shape can reach more than10MPa, and the steel plate of “”shape can effectively enhance the impermeability of the contact surface, which arises from thevertical baffle path of water penetration. In addition, thanks to the shutter that is perpendicular tothe direction of the water pressure, the water penetration can effectively be blocked. Meanwhile,the monitor of displacement and strain shows that the amount of deformation at concrete jointingis larger than that of the wall, considered as the weak areas in the process of the force.By summarizing the above-mentioned results, we can achieve the infiltration mechanism ofthe contact surface that there are numerous interpenetrated micor-holes and micro-cracks to formseepage channels, and the penetration pressure may expand the channels and increase theseepage. Besides, both incorporating expanding agents appropriately in the concrete andincreasing the normal pressure of the contact surface can significantly improve theimpermeability of the contact surface.