| The Cretaceous-Jurassic strata in western China are widely distributed,with a late diagenesis period,poor cementation,low strength,cementation,and sandification.After excavation of the roadway in this type of rock layer,large deformation of the surrounding rock often occurs and the damage is serious.It is difficult to maintain the stability and safety of the surrounding rock of the roadway with the conventional anchor net spraying support technology.Therefore,it is of great theoretical significance and application value to carry out the design and on-site monitoring research of the roadway support in the deep-buried weakly cemented soft rock stratum.The thesis takes the support of Shimen roadway support of Bojiang Haizi Mine+803.5 m in Dongsheng coal field as the engineering background.The research method combining theoretical analysis,numerical simulation,laboratory testing and on-site monitoring is used to analyze its hydrological and engineering geological characteristics.Weakly cemented soft rock roadway softened by water and the combined support mechanism of anchor beam net and spray cable,put forward the design principle and optimization scheme of weakly cemented soft rock roadway support;explore the deformation and stress characteristics of the optimized roadway support structure,And through the on-site monitoring,the rationality and effectiveness of the optimized supporting structure are verified to ensure the safety of the construction and operation of the roadway.The main research content and results are as follows:(1)The weakly cemented formation of the Cretaceous-Jurassic strata in the Bojiang Haizi mining area is a continuous sedimentary rock with the characteristics of sandification and mudification with water,and low compression and shear strength.Among them,the Jurassic rock structure is supported by particles,mainly muddy cement,and the main mudstone mineral components are kaolinite and montmorillonite,and the particles and cement are interstitial structures;the Jurassic middle system,middle and lower The compressive strength of the stratum is generally less than 30MPa,which is mostly soft rock;the physical,chemical and mechanical effects of water on rock mechanical properties are analyzed,and the weakening law of rock mechanical properties under water-rock coupling is revealed.(2)On-site long-term monitoring of the axial force of the anchor rod,the axial force of the anchor cable,and the concrete stress and strain of the+803.5 m auxiliary transportation Shimen roadway.The monitoring results show that it is difficult to adapt to the characteristics of low strength and water softening when using conventional anchor rod or cable end anchoring structure in weak cemented rock layer,which makes it difficult to meet the design requirements for the pretension applied to the anchor cable.In addition,the anchor rod(cable)has tension relaxation phenomenon in the process of stress.(3)FLAC3D numerical simulation software soft rock roadway support stability analysis before and after the support,analysis shows that the optimized support scheme can meet the requirements of the surrounding rock control of the roadway,after the stability of the anchor(cable)Although the tension between the surrounding rock and the surrounding rock failed to meet the design requirements,there was no relaxation of the anchor cable tension before optimization.(4)The research proposed optimization principle of roadway support design and the optimized design plan of the cooperative support design of anchor beam beam spraying cable have effectively improved the synergy between the support system and the surrounding rock,and avoided the anchor rods and cables in the support structure.The function decline due to insufficient anchoring force has been verified by on-site monitoring.It provides a useful reference for roadway support under similar conditions in the future.Figure[43]table[10]reference[62]... |
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