Investigation of the flow distribution in the grouting system and joint when rendering dams monolithic

Abstract

Rendering the construction joints monolithic is particularly important in the design and erection of high concrete dams, especially arch dams when the strength characteristics of the concrete are exploited to the greatest extent. In Soviet practice the pipe system of grouting is usually employed for grouting the construction joints.The piping is laid over the whole area of the joint, divided into grouting maps and joined up with the cavity of the joint by cutlets of various design (point, line, etc.). To improve the conditions of filling the joint with grout, a dentation is worked into the upper part of the map for leacing off the air.A 20:0.4 water-cement grout is used [1] for rendering dams monolithic. Grouts with a water-cement ratio of approximately three and over, approach the properties of viscous, Newton type liquids,while with a ratio less than three they behave like viscous-plastic (Bingham) liquids.The flow conditions of Newton and Bingham liquids in the pipes of the grouting system and the joint may be respectively laminar, transitional or turbulent, or structural, transitional or turbulent. At different parts of the pipe system and in different zones of the joint different flow conditions may be observed.The study of the hydraulic map of joint grouting is carried on along different lines and by different methods. This paper studies the flow and pressure distribution during the grouting of joints, employing the method of electric hydrodynamic analogies.In some cases it is possible to study laminar flow of a viscous (Newton) liquid by the electric-hydrodynamic analogies method. The results set out below may therefore be valid only for the injection into the grouted joint of a grout with a high-water-cement ratio (W/C > 3), when the grout will in essence be a Newton liquid. Investigations using the electric-hydrodynamic analogies method, disregarding hydraulic resistance in the feed system and outlets, were carried out during 1965 [2]. Similar work was carried out for the purpose of more closely simulating actual conditions, taking into account the hydraulic resistance in the pipes and outlets.* Lamina flow of the Newton liquid was assumed in the joint and in the pipes of the injection system. Electrically-conducting paper was used for the model of/he grouting system and joint. At the positions of the outlets, strips of electrically conducting paper simulating the hydraulic resistance in the pipes were connected with a sheet of electrically conducting paper simulating the hydraulic resistance of the joint.The width and resistivigy of the strips were taken in accordance with the equation where b 1 and Pl, b2 and Pz are respectively the width of the tape and the resistivity of the electrically-conducting paper, simulating the hydraulic resistance in pipes with diameter d i and d z.In order to find the relationship between the joint opening and the resistivity of the sheet of electxicallyconducting paper simulating its hydraulic resistance, use was made of the equation *See Gidrospetxsproekt report "Investi...