Study on Creep Model Selection and Long-term Stability of Soft Rock Chamber Group
The service life of the chamber is long,and the surrounding rock will creep with the accumulation of time,re-sulting in weakening or even failure of the support,thus affecting the safety of the mine.In order to study the creep characteris-tics of surrounding rock of engineering soft rock chamber,the bottom chamber group of Zhongjiu Iron Mine was taken as the re-search object.Firstly,the high temperature triaxial rheological test system of ROCK1000-50 VHT rock was used to carry out the triaxial creep test under the confining pressure of 5 MPa,10 MPa and 15 MPa,and the creep and failure characteristics were analyzed.The test results show that the creep failure of diorite is mainly shear failure under low confining pressure.When the confining pressure increases gradually,it will be transformed into splitting failure.Under the condition of triaxial stress,the creep of diorite will have four stages:compaction,elasticity,crack propagation and failure.When the loading stress is low,the diorite will have constant creep after the instantaneous strain,and then the axial strain gradually tends to be stable.However,when the loading stress is high,the time for the rock mass to enter the constant creep stage becomes longer,and the axial strain increases continuously.According to its creep characteristics,the Burgers model is selected to establish the constitutive equa-tion.After fitting,it is basically consistent with the creep test curve,indicating that the constitutive model can reflect the creep mechanical properties of diorite.Finally,the Burgers creep constitutive model is used to simulate the chamber support model based on FLAC3D.The results show that the existing support scheme can maintain the long-term stability of the chamber group.The research has reference significance for the timeliness analysis of soft rock chamber group support.
chamber groupengineering soft rockcreep characteristictriaxial creep testBurgers model
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