Study On The Jet Grouting Enclosure Structure Design And Stability With Inclined Shaft Cross Saturated Sand Layer

Coal resources have been an important material foundation for national economic and social development in the past few decades and in the foreseeable future.Whether a mine can be built depends first on the shaft sinking technology,the construction technology of inclined shaft cross saturated sand layer has always been a domestic and international problem.The jet grouting process includes controllable and reliable grouting effect,and has permanent protection against the shaft,so how to form enclosure structure by the jet grouting process shielding inclined shaft cross saturated sand layer will be important theoretical guidance and significant practice promotion meaning.This article studies the stability of jet grouting enclosure structure with inclined shaft cross saturated sand layer through field tests,indoor tests,theoretical analysis and numerical simulation,and initially forms a set of design methods and criteria for determining stability of jet grouting enclosure structure,the main conclusions as follows:(1)Through indoor tests,the physical and mechanical properties of wind-blown saturated sand and jet grouting induration in northern Shaanxi are obtained:the water content,bulk density,specific gravity of sand soil,and Duncan-Chang model parameters;the bulk density,uniaxial compressive strength,cohesion,internal friction angle,elastic modulus and poisson ratio of jet grouting induration.(2)Through theoretical analysis,inclined shaft is divided into shallow and deep section according to the critical depth.The surrounding rock pressure is calculated by rock column method in shallow section.After analysis and comparison,with reference to the various theories of the mechanism,characteristics and scope of application,the surrounding rock pressure is calculated by<railway tunnel design specifications>in deep section in the final.(3)Through theoretical analysis,the mechanical model of jet grouting enclosure structure is established,and the thickness calculation formula of roof,floor and two sides are determined.The force form of jet grouting enclosure structure is calculated by the model of the maximum shear force under the beam,and the forces of the two sides are considered by the most unfavorable circumstances.(4)According to the experimental results,the thickness of the design value and change rule is calculated in shallow and deep section.The thickness of shallow section is linearly increasing with depth,and the thickness of the deep section does not change with the depth.(5)Through numerical simulation,three transects of 16.6m,50m and 80m buried depth are chose to verify analytical solution,the correctness of the thickness formulas of jet grouting enclosure structure deducted in this papper is proved.Research shows that the enclosure structure by jet grouting process shielding inclined shaft cross saturated sand layer is feasible,its theoretical method and evaluation criteria is applicative and correct,jet grouting enclosure structure is stable.So the obtained mechanical model and formulas of jet grouting enclosure structure can be used as a standard of the design and stability of jet grouting enclosure structure with inclined shaft cross saturated sand layer.