Mechanical Research On Shaft Lining Based On The Process Of Segmented Excavation And Outer Lining With Continuous Inner Lining In High Pressure Rocky Aquifer Sunken By AGF

The coal resources in the west of China are buried deeply.Although the overlying alluvium is shallow,the bedrock contains many aquifers and the depth of burial is large.In addition,the bedrock is weak,the pores contain water,and the depositability is poor.These characteristics have brought new opportunities and new challenges for the development of artificial freezing method of shaft sinking technology.According to the existing design code or engineering experiences,the frozen wall and the shaft lining in deep rocky aquifer are often designed too thick,and the concrete grade of the shaft lining even exceeds C75.However,the design does not guarantee the waterproof and load-bearing effects of the shaft,and the grouting of annulus between or behind the two linings is needed to be repeated in the shaft lining.It not only increases the cost of the shaft construction,but also delays the construction progress of the shaft.The design of "frozen wall and shaft lining" in west shaft sunken by AGF is increasingly away from the "experience gains" of engineers in many practices.There are many doubts about the application of the eastern alluvium frozen design theory to western.According to the characteristics of the high pressure rocky aquifer in the west,and based on the interaction of surrounding rock,high water pressure and shaft lining,this dissertation studied the mechanical property of shaft lining under the special temperature environment by using the modern geotechnical multi-field theoretical analysis and the advanced numerical calculation.In this dissertation,the auxiliary shaft construction of Inner Mongolia Yingpanhao coal mine was taken as the research background.And the research could provide a reliable theoretical basis for the design and construction of the shaft lining sunken by AGF,which based on the process of segmented excavation and outer lining with continuous inner lining.The main research work is listed below.1.Considering the interaction between the surrounding rock and the frozen wall,the mechanical analysis of the plane-elastic-plastic computational model and finite-length computational model of frozen wall were carried out.The distribution of stress field,displacement field and its influence law were studied,and the relevant discriminant for the temporary plastic state was obtained.From the perspective of mechanics,the design and safety evaluation of the frozen wall and the outer lining were answered.2.For the special construction environment of the shaft sinking by AGF,a finite element inversion method for temperature field was established,and the error between calculated results and measured data is small.In addition,the temperature field distribution and development of shaft lining during construction were mastered.3.In this paper,the mechanism analysis and the construction of the mechanical model of the shaft lining’s thermal stress during construction were carried out.The analytical expressions of the themal stress and strain were obtained.In addition,the application of the calculation example was carried out,and the position of the weak point of the shaft lining was analyzed.4.Based on the coupling of temperature field and stress field,the mechanical model of permanent support for the shaft lining in deep rocky aquifer was established in this paper,and the distribution expressions of the stress and displacement fields were obtained.Based on the third strength theory,a new design formula for the shaft lining in deep rocky aquifer was deduced.The applicable conditions of the formula were discussed initially,and the allowable maximum value of drop in temperature,and limit design depth of the shaft lining were obtained.5.Based on the analysis of measured data and the finite element numerical calculation during the construction period,the distribution law of stress and strain of the concrete in shaft lining were mastered and compared with the actual measurement.At last,from the view of the mechanism of thermal stress and the construction process,the countermeasures for the prevention and control of the thermal stress on the shaft lining of deep vertical shaft sinking by AGF were proposed.