Bearing Characteristics And Design Method Of Double-layer Combined Shaft Lining In Water-rich Strata

In recent years,the freezing method has been widely used for shaft sinking in deep water-rich rock strata.The traditional double layered composite shaft wall structure designed with large thickness,easy cracking,and high cost can no longer meet engineering needs.Therefore,it is imperative to develop a new type of frozen shaft lining structure suitable for water-rich strata.This article is based on the concept of using the combined bearing of inner shaft lining,outer shaft lining,and surrounding rock to reduce the thickness of the shaft lining.A new type of double layer combined shaft wall structure is proposed,and the construction process of this new type of shaft wall structure is studied by comprehensively using theoretical analysis,numerical simulation,and physical model testing methods.The stress,displacement distribution,and evolution laws of the shaft wall and strata at different construction stages are obtained,A design method for double layered combined shaft lining in water-rich strata was constructed.Firstly,the construction process of the double layered combined shaft wall was proposed,and the requirements for the physical and mechanical properties of the bonding material between the inner and outer shaft linings,such as micro expansion,high compressive strength,and high bonding strength,were given;We conducted physical and mechanical properties tests on the bonding material and obtained the mechanical parameters of the bonding material: compressive strength of 78.50 MPa,expansion rate of 0.11%,and bonding strength of 3.02 MPa after 28 days,meeting the physical and mechanical properties requirements of the bonding material for the double-layer combined shaft lining.Secondly,the stress characteristics of the double-layer combined shaft lining and the formation during the construction and use stages were analyzed,and a model of the interaction between the double-layer combined shaft lining,frozen wall,and surrounding rock was established.The stress and displacement analytical solutions of the inner lining,outer lining,and formation in each stage were derived,and verified using numerical calculation methods;Through analytical analysis and numerical calculations,the distribution and evolution of stress and displacement in the shaft lining and formation at various stages were obtained,and the external load characteristics,main influencing factors,and influencing laws of the shaft lining during interaction with the formation were mastered.The results indicate that the pre compression stress of the bonding layer and the pore water pressure coefficient of the outer lining are the main influencing factors.Thirdly,similarity criteria have been derived,specialized grouting equipment and systems have been developed,simulation test benches have been built,and large-scale physical simulation tests have been conducted on the injection process and bearing characteristics of double-layer combined shaft lining bonding layer materials;Obtained the variation patterns of apparent resistivity and inversion resistivity,and identified the solidification time and distribution characteristics of the slurry between shaft linings;Revealed the deformation law of the shaft lining during the injection and solidification process of bonding materials;The critical water pressure for shaft lining detachment,the ultimate bearing capacity of the shaft lining,and the fracture characteristics were obtained.The results show that under the experimental parameters in this article,the thickness of the interlayer between the shaft linings is about 1mm;The expansion pressure stress generated by the bonding layer is about 0.38MPa;The pre compression stress between the shaft linings generated by the solidification of the bonding interlayer is about 3MPa;When the water pressure is less than 8MPa,the double layer combined shaft lining bears the load together,and when the water pressure reaches 14 MPa,the inner and outer shaft linings are completely peeled off;The ultimate bearing capacity of the shaft lining reaches 19.8MPa;The predicted distribution characteristics of the interlayer bonding material obtained by inverting the variation law of resistivity are consistent with the actual situation;The fracture orientation of microseismic positioning is basically the same as the actual orientation of shaft lining fractures.Finally,a design method for double layered combined shaft lining in water-rich strata was proposed,and the design formula for shaft lining thickness was derived;Obtained the main influencing factors and laws of shaft lining design thickness;Based on the engineering conditions of the west intake shaft of Gaojiabao Coal Mine,a double layered combined shaft lining structure design was completed.Compared with the double layered composite shaft lining structure,the total thickness of the shaft lining was reduced by 43%;The achievements have been successfully applied to the west intake shaft of Gaojiabao Coal Mine,setting a world record of 990 m deep freezing method in water-rich rock strata.The research results of this article can provide technical support for significantly reducing the thickness of frozen shaft linings and saving huge sinking costs,and have important theoretical and practical value.In this thesis,there are 164 figures,37 tables and 138 references.