Safety Evaluation And Failure Mechanism Of Double Layer Reinforced Concrete Shaft Lining Based On Safety Factor

Shaft lining in deep alluvium is in complex environment, shaft lining is inevitableimpacted on the change of surrounding environmental factors. Temperature and groundwater are the major factors affecting the shaft lining rupture, shaft lining verticaladditional force generated by temperature and groundwater is the main reason to causethe shaft lining rupture. Therefore, study on the shaft lining mechanical state generatedby the change of temperature and groungwater, analysis the mechanical state of shaftlining evolution in different temperature are important to understand the mechanism ofshaft lining rupture, prevent the rupture of shaft lining, improve the design theory ofshaft lining. The main research worK based on the monitoring data and ABAQUS canbe summarized as follow:(1)Through studing the strain, stress, plastic zone of concrete and reinforcingmesh, in the double layer reinforced concrete shaft lining at failure load.Concluding therupture mechanism of double layer reinforced concrete shaft lining, when the shaftlining fracture, the inner concrete, internal pressure bar, outside concrete, externalpressure bar, internal stirrup, external stirrup yields in turn.(2)Concluding the safety factor of double layer reinforced concrete shaft lining atbrinK destruction is1.1, when the vertical additional force is95KPa, based on theinternal pressure bar yield as the sign of double layer reinforced concrete shaft liningfailure.(3)Studing the safety factor of double layer reinforced concrete shaft lining withthe change of hydrophobic additional stress and temperature stress, based on themonitoring data of Jining No.3main shaft. By comparing the hydrophobic additionalstress and temperature stress influence on safety factor, drawing the hydrophobicadditional stress is the main factor to shaft lining rupture, temperature sress is theinevitable factor.(4)Simulation of vertical additional strain at measuring point is consistant with themonitoring vertical additional strain, when the shaft lining inside temperature is35℃ (inside and outside temperature is20℃) and hydrophobic additional stress is65KPa.Jining No.3shaft in safe state with safety factor is1.2.(5)Improving the strength of concrete in double layer reinforced concrete shaftlining, can reduce the internal pressure bar stress and raise the safty factor as well, sothe safety of double layer reinforced concrete shaft lining increase.