Stress Mechanism Analysis And Safety Monitoring Research On Simultaneous Water Loss Shaft Wall Of Upper And Lower Aquifers In Alluvium

Shaft,as an important passageway of mine,connects ground and underground,which is related to the safe production of mine.When the shaft passes through the deep alluvium,a wide range of shaft wall fracture accidents have occurred in many mining areas in China,which seriously threatens the safe production of the mine.Therefore,it has important practical value for failure mechanism analysis,long-term monitoring,safety evaluation and fracture prevention of shaft lining under similar conditions.Taking the auxiliary shaft of Qianyingzi Coal Mine as engineering background,this paper carries out stress mechanism analysis and safety monitoring research on simultaneously water loss shaft wall of upper and lower aquifers in alluvium to prevent shaft wall fracture.In view of the engineering geological and hydrological conditions of simultaneous water loss of the upper and lower aquifers in the alluvium near Qianyingzi Coal Mine Industrial Plaza,the paper systematically studies the stress mechanism and safety monitoring of the sidewall of the auxiliary shaft in Qianyingzi Coal Mine by means of theoretical analysis,numerical simulation and on-site monitoring and evaluation,with the main contents as follows.The stress of shaft wall under combined action of temperature stress,dead load,lateral pressure and vertical additional force of water loss settlement is analyzed by theoretical analysis method.Simplified calculation formula of stress of shaft wall under combined action of above forces is obtained by superposition principle.Using FLAC3D numerical simulation software,a fluid-solid coupling model was established to analyze the additional force on the shaft wall and the settlement of surrounding strata in the alluvium of Qianyingzi Coal Mine under the conditions of simultaneous loss of water in the upper and lower aquifers,pumping only and bottom hydrophobic only.The results show that with the development of pumping and hydrophobic,the formation settlement increases continuously,and the maximum settlement values under various conditions are obtained.It shows that the main cause of formation settlement is water trapping,which causes the vertical stress in the shaft wall to increase greatly.The maximum values of the present stress and vertical stress of the shaft wall are obtained by simulation calculation,which provides a basis for the safety state analysis of the shaft wall.Long-term safety monitoring scheme for sidewall of auxiliary shaft in Qianyingzi Coal Mine is formulated,relevant warning values are calculated,and three monitoring levels are arranged in the auxiliary shaft.The analysis of test data in recent two years shows that the tensile and compressive strain values of real logging wall concrete are less than early warning values at present,and the rate of vertical compressive deformation of shaft wall in Qianyingzi Mine auxiliary shaft is small,which indicates that the shaft wall is in a safe state at present,but the general trend is increasing gradually,so monitoring should be strengthened.At the same time,the monitoring results also show that the variation trend of shaft wall increases in summer,which indicates that the influence of temperature on stress and deformation of shaft wall is an important factor.Finally,three schemes for preventing shaft wall fracture in Qianyingzi Coal Mine auxiliary shaft are put forward.Through analysis and comparison,it is recommended to adopt the scheme of cutting a pressure relief tank,and design parameters and implementation steps are given,which have important reference for preventing shaft wall fracture.Figure 51 Table 5 Reference 70...