Cracking Analysis of Spiral Case Structure with Combinatorial Embedding Manner of Large Underground Power Station Turbine Unit

摘要

The spiral case with combinatorial embedding manner is a novel design and inherits the advantage of the general types of embedding manners of embedded with cushion layers and embedded directly, which is progressively used in hydro projects. In the present paper, the mechanical behavior of a larger spiral case with combinatorial embedding manner is analyzed by using 3-D non-linear finite element method. The deformation of the spiral case structure and crack analysis of outer reinforced concrete structure are carried out. The strengthening measures under the engineering control criterion are also discussed. The results show that the penetrating crack will appear in the concrete and the relative rising displacement of generator pedestal structure is out of the control criterion if no strengthening measures implemented. Increasing the quantity of reinforcement only is not able to hold back the penetrating cracks. The enhancement of the tensile strength of concrete is an effective way to decrease the range of crack propagation, resist the penetrating and decrease the rising displacement of generator pedestal structure. It also indicated that extending the laying length of cushion is another effective way to decrease the rising displacement of generator pedestal structure.