The effect of the thermal conductivity by the materials of contact surfaces on the heat balance of the jet-grouting drill stem hydraulic elements

The paper is deals with the influence of thermal conductivity and the materials of the contact surfaces of the drill shaft and the sealing element on the change in the thermal balance of the structural unit «drilling string» used in the jet grouting technology to fix weak and unstable types of soils. A model with nodes for the computational grid of the “hydraulic puller” assembly unit is shown, part of which are the considered drill shaft and sealing elements. The temperature values are calculated by the finite element method in the «Siemens Femap's» environment depending on the change in the thermal conductivity coefficients of the contacting elements. Calculations were carried out for the fourth part of the indicated model, due to the axisymmetry of the problem being solved, this made it possible to significantly reduce the amount and time of calculations. Graphs of the corresponding dependence are constructed for a number of points located in the characteristic areas of the hydraulic stripper. Also, by power regression, expressions were obtained that allow calculating the temperature values in the indicated areas of the considered assembly. The obtained dependencies will make it possible in the future to select the material for the drill shaft of the hydraulic puller based on the optimal ratio of the thermal conductivity of the shaft, its corrosion resistance, determined by the chemical composition of the steel and the thermal conductivity of the sealing.