Study On The Calculation Method Of Freezing Inner Wall In Inclined Shaft And Design Software Package Development

In order to meet the requirements for freezing sinking of inclined shafts in the water-bearing strata of West China, this paper carried out a study on the mechanical properties of the inner wall which in the double-layer composite frozen wall of inclined shafts in the water-bearing strata. And a new design method of the inner shaft wall was made. Finally, the FSL_CAD(Computer Aided Design of Freezing Inclined Shaft Lining) software package was developed according to the results of numerical calculation and the approximate solution.Firstly, Four arc general thickness wall mechanics was established and according to the loadbearing features of inner frozen wall of inclined shafts, this paper created a numerical calculation model of inclined shaft wall with or without the restriction of wall rock, and specified how the combination of geometric parameters of the shaft wall is related to the elastic mechanical properties of it. The study of numerical calculation shows the following features: the restriction of wall rock changes the deformation pattern and stress value of shaft wall, but the tensioncompression status remains unchanged; hoop stress value and the geometric parameters of shaft wall exist the following relations: the top arch radius have a linear relation to the hoop stress in top arch; and the radius of inverted arch have a square monotonic relation to the hoop stress in inverted arch; and wall thickness have a cubic relation to the hoop stress in each point.Secondly, the model which is different thickness in inverted arch was estabished, and specified how the combination of geometric parameters of shaft wall is related to the elastic mechanical properties with or without the restriction of wall rock. The study showed the following features: the model of increasing the inverted arch thickness can reduce the inward deformation of borehole wall effectively without regard to the restriction of wall rock, and the max deformation reduction is 60% in inverted arch section. At the same time, It can reduce hoop stress at every point; the model with the restriction of wall rock works on the inverted arch mainly, and almost have no effect on the hoop stress and radial displacement in top arch and side wall. It can reduce the hoop stress and radial displacement, and hoop stress changes more gently in inverted arch. Study suggested that fill and level up the inverted arch inner edge bridge during the construction.Thirdly, the paper studied the general model approximation algorithm, obtain the method of framework model and curved beam model based on the method of structural mechanics and the Winkler foundation beam theory, and put forward three kinds of model of the inverted arch with different thickness. The research showed that the framework model approximation algorithm can be calculated without regard to surrounding rock when the ratio of the wall thickness and wall span is no greater than 0.14, load or axis correction should be carried out on the model when outside this range. Curved beam model considers the influence of surrounding rock, and achieves more appropriate conclusions compared with the actual through many iterations. The analysis of three kinds of different thickness model shows that the model C of which inverted arch different thickness is the best model and should be used in practical engineering.Finally, the FSL_CAD software package was developed based on the results of numerical calculation and the approximate solution,the paper summarized the design of the inner wall which in the double-layer composite frozen wall of inclined shafts in the water-bearing strata. Then, put forward that the structure with inverted arch should be choosen in the design, and the radius as smaller as better. The FSL_CAD software was used for instance trial, and the experimental results showed that the FSL_CAD software is successful and convenient.To sum up, inverted arch has a great influence to the stress and displacement of the wall as a whole, the reasonable design of inverted arch can reduce the internal force and the wall thickness of wall model effectively. Design load should consider all the water pressure, and the wall should be designed according to the control point stress is less than the comprehensive strength of concrete.