Study On Intereaction Between Surrounding Rock And Shaft In Deep Vertical Shaft Based On Cavity Expansion Method

To solve the problem of the interaction between surrounding rock and shaft is key to vertical shaft construction in deep rock strata in western China region and to shaft lining design theory and method optimization.At the present stage,the shaft engineering in China is extended from the shallow part to the deep part,and transferred from the eastern region to the wester region.Because the traditional shaft lining design method applied to shaft in deep rock strata cannot meet many requirements such as safety and economy,it is necessary to improve the existing vertical shaft lining design method.In this paper,the studies on the stress law of shaft lining structure in the process of interaction between surrounding rock and shaft is carried out with combining theoretical analysis,numerical calculation and field measurement.And the vertical shaft lining design principle and method in deep rock strata is put forward,which can provide basis for new mine engineering construction in China.The progresses and main research achievements are listed below:(1)Based on the cavity expansion method and considering the time-dependent characteristics of the development of the surrounding rock stress and deformation of the vertical shaft,the elastic-viscoplastic model of the surrounding rock including the elastic zone and the plastic development zone is established.The distribution of stress and displacement in deep rock strata and the law of change with time are obtained.(2)According to the variation of elastic modulus of concrete with time,the characteristic curve of shaft lining structure constructed by different grade concrete is established.According to the compression characteristics of foamed plastic sheet,combining with the characteristics of concrete,the characteristic curves of composite shaft lining structure are established.The influence of different time,strength grade of concrete and thickness of shaft lining on the characteristic curves of shaft lining structure is analyzed.The results show that the shorter the time,the lower the strength grade of concrete and the thicker the shaft lining,the smaller the load on the shaft lining structure.(3)On the basis of surrounding rock characteristic curves and the shaft lining characteristic curves,the model of interaction between the surrounding rock and shaft in the deep rock strata is established,the mechanism of interaction between the surrounding rock and shaft is revealed,the numerical calculation procedure of interaction force between surrounding rock and shaft is developed.And the effects of different shaft engineering features,surrounding rock features and shaft lining features on shaft lining forces during the interaction between surrounding rock and shaft lining are obtained.The results show that the process of deep shaft excavation and lining support has complex space-time effect.When the shaft diameter and shaft lining thickness are large,the interaction force between surrounding rock and shaft is large.The cohesive force,internal friction angle,residual cohesive force,residual friction angle,elastic modulus and Poisson’s ratio of the surrounding rock affect the interaction load between surrounding rock and lining.The plastic viscosity coefficient of the surrounding rock has significant influence on the development of the interaction load.The reasonable application time of the lining structure has an important influence on the interaction load between the surrounding rock and shaft lining.The concrete grade of shaft lining has little effect on the interaction force between surrounding rock and shaft lining.(4)Based on the above research results,the design principle of shaft wall is put forward,and the design method of shaft lining which can reflect the interaction between surrounding rock and shaft is constructed.By the design method of shaft lining in this paper,the design calculation of shaft engineering in western region is carried out and the thickness of shaft lining is determined.The analysis shows that the interaction load between surrounding rock and shaft determined by the method in this paper has clear theoretical basis and physical significance,which is more in line with engineering practice.