Study On Structural Characteristics Of The Spiral Case Of Hydropower Station Standing With High-head Water Pressure

Liuhong Hydropower Station, with a high water head more than 390m, is the fifth stage of project built on Meigu River. Three francis turbine-generator units with total capacity of 180MW are installed in the hydropower station. The spiral case, with 1.3m in diameter and 38mm thickness at inlet section, is very complicated and stands with very high water pressure. As an important component of the turbine-generator, the spiral case of Liuhong Hydropower Station faces a lot of new problems. So how to design the spiral case and surrounding reinforced concrete directly affects long and safe operation of the power station.After comparing with the other similar project and considering the requirement of stable operation of units, a structural form, filling water and keeping certain pressure in the spiral case when casting surrounding concrete, is to be used in Liuhong hydropower station. In order to optimize the pressure value of the spiral case when casting concrete and reinforcement of surrounding concrete, following research contents are carried out in this paper.(1) Investigating the technology, pressure value, spending and construction progress of the turbine spiral case to some projects in China or abroad, in order to refer for the structural design of contributors in Liuhong Hydropower Station.(2) Comparing the operating condition of units, stress and displacement state of the spiral case and surrounding concrete under different water pressure, so as to optimize the pressure value of the spiral case in Liuhong Hydropower Station when concrete is placed.(3) Calculating the thermal stress and strain of the spiral case and surrounding concrete under the temperature load so as to study the effects of temperature load.(4) Studying the stress distribution of the spiral case, reinforcement and cracking development of surrounding concrete by means of 3-D non-linear finite element analysis, in order to obtain a feasible reinforcement amount and arrangement.(5) Carrying out 3-D finite element dynamic analysis so as to study the self-vibration frequency and vibration characteristics of the spiral case and hydropower plant structure.