Design And Safety Monitoring Of Retractable Shaft Lining Structure In Freezing Shaft

Since the 1980 s,shaft lining rupture accidents have occurred frequently in Huanghuai and Xuhuai areas of China.Many experts and scholars have found that when the shaft lining passes through special strata,it will be subjected to vertical additional force because of the water loss of the bottom aquifer.When the vertical additional force exceeds the ultimate bearing capacity of the shaft lining,the shaft lining will break.The Xuhuai mining area where the new auxiliary shaft of Qianyingzi Coal Mine is located in this paper generally shows the characteristics of large formation hydrophobic settlement and high vertical additional force of the shaft,so when designing the shaft wall structure,it is necessary to add a retractable shaft lining joint to attenuate the vertical additional force and prevent shaft lining fracture.At the same time,the test elements are embedded in the key layers of the shaft lining to monitor the stress and deformation of the new auxiliary shaft from construction to service for a long time,and its safety is evaluated.The main research contents are as follows:(1)The author selected the setting horizon of retractable shaft wall joint according to the engineering geological conditions of new auxiliary shaft in Qianyingzi Coal Mine.The design principle of the retractable shaft wall joint is expounded.According to the simplified design theory,the joint size parameters and structural form are designed.The design content mainly includes the thickness of the inner vertical plate,the thickness of the outer vertical plate,the position of the vertical plate,the width of the flange plate and the thickness of the flange plate.(2)Taking the retractable shaft lining joint of the new auxiliary shaft as an engineering example,the finite element model is established by using ANSYS software.Firstly,the vertical and horizontal bearing capacity of the shaft lining joint is analyzed.Then,the vertical bearing capacity of the shaft lining joint with different vertical plate thickness is compared with the theoretical calculation value to verify the rationality of the numerical analysis.Finally,the vertical bearing capacity of the shaft lining with different sizes is calculated,and the influence of the size parameters such as the position of the joint vertical plate,the width of the flange plate and the thickness of the flange plate on the vertical bearing capacity is analyzed.The results show that the vertical plate of the joint is far away from the center of the shaft,and the smaller the width of the flange plate,the higher the vertical bearing capacity,while the thickness of the flange plate has little effect on its vertical bearing capacity.The influence of material yield strength and horizontal load on the vertical bearing capacity of shaft lining joint is also analyzed.(3)A new auxiliary shaft monitoring system is established by using vibrating string pressure gauge,steel bar gauge,strain gauge,water pressure gauge,displacement gauge,intelligent sensor acquisition box and other components and equipment to monitor the stress and deformation of the contractible shaft lining structure in the new auxiliary shaft in real time.Based on the monitoring data from well construction to service,the variation laws of pressure between walls,steel bar stress,concrete strain,water pressure between walls and vertical compression of retractable shaft lining joints are analyzed in stages,and the dominant factors causing stress and deformation changes in each stage are pointed out.Figure [48] Table [15] Reference [76]...