The Surveillance And Study Of Thermal-Creep Stress Of The Thick Concrete Liners With Big Diameters During The Construction In The TGP

About mass concrete structures, owners, designers and contractors are all interested in the temperature and thermal-creep-stress field. As we all know,the hydration of concrete is a radiative process, which might lead to emergence of,cracks in the early age of concrete while the heat cumulated exhales. Thus great disadvantage may be engendered as far as seepage prevention, erode resisting and the whole structure maintaining are concerned.In this paper, basing on the data analysis and stimulating analysis of the concrete liner of the water diversion tunnel of the underground hydropower station in the right bank of the TGP, the distribution and influential factors of the thermal-creep stress of thick concrete liners with big diameters in the TGP are studied. The following several problems have been solved:1. On the basis of functional of the unstable 3D temperature field, the spatial and temporal sepration of the FEM implicit solution are studied, and the control equation of the FEM calculation is derivated.2.The FEM calculating program of the 3D unstable temperature field is developed, and with the emulator technique, the simulating calculation has also been studied. Some examples which have analytic solutions used to validate the program indicate that the program is completely correct.3. The iterative algorithm of the 3D unstable temperature field which takes the effect of water pipe cooling into account has been studied, and some skills about determining the nodes and elements of water pipes are also given.4. The recurrence formula of the creep strain is the key of FEM calculation of creep stress. In this paper the exponential function is usedto figure the creep strain, and the recurrence formula of 3D creep strain at any periond of time is derivated.5. The FEM calculating method of thermal-creep-stress is studied, and the corresponding program has been developed. With the international program of ANSYS , the program is validated as being right.6. The distribution and influential factors of thermal-creep-stress of the thick concrete liners with big diameters during the construction of the TGP are studied by combining the analysis of field monitoring data and the stimulating FEM calculation. Many conclusions which are useful in the practice are given in the end of this paper.