Study On Variation Law Of Shaft Wall Additional Force Under Hydrophobic Condition Of Multiple Aquifers

Nowadays,vertical shaft fracture disasters occur one after another,and additional force is the main reason for shaft wall fracture,and additional force is caused by hydrophobic consolidation settlement of the formation.At present about bottom contain hydrophobic additional force change law has many experts and scholars to study,but many aquifer hydrophobic cases additional force law and relationship remains to be seen,the parameters of neighbouring water-resisting layer and aquifer corresponding deformation will occur,so the aquifer formation occurred more hydrophobic settlement regularity of shaft wall vertical additional force is of great significance.End of this article is based on contain hydrophobic research,on the basis of theoretical analysis,numerical simulation and field measurement,the method of combining research aquifer when the hydrophobic settlement calculation method and the change law of vertical additional force and use the long-term monitoring data of typical wellbore by additional force and sidewall safety status was evaluated and forecast analysis.First of all,based on the existing experts and scholars on shaft lining near the bottom aquifer of overburden and bedrock interface hydrophobic subsidence theory research present situation,the additional force when establishing many aquifer hydrophobic settlement of borehole wall vertical additional force calculation model,considering the effect of aquifer,in central calculate different soil subsidence,the aquifer(sand)settlement is transient subsidence;The settlement of the water-repellent layer(clay layer)is the consolidation settlement,which is divided into unidirectional consolidation and bidirectional consolidation according to the different soil layer positions,and the total settlement amount of the stratum when the hydrophobic settlement of multiple aquifers can be obtained.Considering the settlement deformation caused by the reaction of the additional force on the stratum,the relative displacement between the shaft and the stratum is obtained,and the calculation formula of the additional force is obtained according to the pile foundation theory.The calculating model of shaft wall force is established,and the calculating formula of shaft wall anisotropic stress under the action of dead weight,lateral pressure and additional force is obtained.Secondly,according to the actual formation conditions of multiple engineering thick surface soil wellbore through,a more practical numerical calculation model of multi-aquifer hydrophobic settlement wellbore was established,and typical parameters were used to study the change of stress,displacement and additional force of wellbore wall under the initial formation state,wellbore wall and formation equilibrium state,and formation hydrophobic state.By changing the value range of influence factors,the single factor scheme is adopted to analyze the influence of different factors on the variation law of additional stress.The results show that the additional stress is directly proportional to the thickness of the topsoil layer,the head drop,the amount and thickness of aquifer,and inversely proportional to the thickness of the shaft wall and the depth of the middle bearing.The comparative analysis shows that the variation law of the additional force obtained by the theoretical analytical solution is in good agreement with the numerical solution,and the theoretical analytical solution is basically correct and has high reliability when applied to practical engineering.Finally,based on the research achievements of theory analysis,the typical engineering cases(dongtan west air shaft)model is simplified,and the water level monitoring data,borehole wall formation parameters into the theory of above formula to calculate the change rule and the size of the additional force,again by attaching to the theoretical value against performance wall the theoretical value of strain and ground subsidence,comparing with the theoretical calculated values and measured values,the result of the effect is good,analysis,establish the aquifer more hydrophobic cause analysis method to calculate the additional stress of shaft wall has high reliability.Then the force and deformation of the auxiliary shaft and the north shaft of Dongtan coal mine under the action of additional force are analyzed,and the safety of the shaft wall structure is predicted.The thesis has 97 figures,50 tables and 109 references.