The Law Of Tunnel Rockburst Energy Variation And Engineering Application Under The Force-heat Coupling Action

With the rapid development of deep underground excavation projects in recent years,many deep underground projects are under overall planning or construction.However,rock bursts,water bursts,rock bursts,gas explosions,high ground temperatures,etc.often occur during the construction of deep projects.Major disaster.This paper carries out inversion analysis on the characteristics of the in-situ stress in the area where the Bayu tunnel project of the Lalin Railway passes through,and combines the problems of high in-situ stress and high ground temperature in the excavation process.From the perspective of the force-heat coupling effect,the tunnel excavation and rockburst are analyzed.Analysis of occurrence,prediction,prevention and other issues.Based on the energy principle,the mechanism of rockburst in Bayu tunnel under the coupling of force and heat,its generation form,the relationship between rock failure and energy conversion,and rockburst risk prediction during tunnel excavation have been studied,and the following results have been obtained:(1)Based on the principle of energy and the law of thermodynamics,this article explains the mechanism of rockburst from the perspective of energy conversion:the rock mass is loaded by external force to do work,so that its core element collect energy,and portion of the energy is adapt into the microstructure indoor the rock physique.The immoral energy of flaw and pliable pull(unalterable),and the other part of the energy becomes the resilient pull energy deposited in the element(revocable).The rock mass will release stress due to excavation disturbance.Under the influence of unloading,the internal The stored elastic energy is also released.When the elastic energy released by this part exceeds the energy value required for the destruction of the rock mass unit,rock burst failure will occur.(2)Through the three-dimensional in-situ stress inversion and comparison with the actual exploration results,it is determined that the initial in-situ stress of the Bayu tunnel is mainly tectonic stress,and the guidance of the supreme pmain stress is the leave direction.Based on the aforementioned energy principle,the elastic strain energy density formula is given,combined with the elastic strain energy density formula,the energy change of the surrounding rock during the simulation process is quantified,and a rockburst simulation method for tunnel excavation under the coupling of force and heat is formed.(3)Under the same ground stress(53MPa),the final plastic zone volume at 20℃ is3348m~3,the final plastic zone volume at 30℃ is 3391m~3,the final plastic zone volume at 40℃ is 3423m~3,and the final plastic zone volume at 50℃ is 3458m~3;Excavation under different ground stresses,after the completion of the tunnel excavation under the action of 53MPa,30℃,the final plastic zone volume is 3391m~3,65MPa,and the final volume of the plastic zone is4231m~3 under the action of 30℃.After the tunnel excavation is completed under the action of75MPa and 30℃,the final plastic zone volume is 4848m~3.It can be seen that under the same ground stress,the higher the temperature,the greater the elastic energy stored in the rock mass unit,and the plastic failure after excavation The range is also larger;and under the same temperature,the larger the initial ground stress,the larger the range of damage that may occur after the excavation is completed.(4)Through the study of the energy change law of the surrounding rock during the excavation process,under the same ground stress,the higher the temperature,the higher the initial accumulated elastic energy of the rock mass unit.After the excavation is disturbed,the energy is mainly based on the pressure relief.The elastic energy is released in the form and the transformed plastic properties are extremely low;in the energy re-accumulation stage,under the influence of 20℃、30℃、40℃、50℃,the energy accumulated in each part of the surrounding rock is similar,while the transformed plastic properties are far Below its elastic energy,the risk of rock burst is greater.Under the condition of 30℃,tunnel excavation under the influence of 65MPa,the initial energy storage and energy release are higher than tunnel excavation under the influence of 53MPa,and in the stage of energy re-accumulation,the elastic energy accumulated at the arch and shoulder Higher,so that the risk and intensity of rockburst rise sharply.(5)Based on the rockburst energy criterion,it is determined that during the excavation of the tunnel,there is a risk of strong rockburst damage at the top of the arch,the risk of moderate and slight rockburst damage at the arch shoulder,and the risk of rockburst damage at the side wall.The risk of rockburst damage with very slight intensity is generated;combined with the inversion of in-situ stress characteristics,prediction of possible rockburst sections and rockburst grades across the tunnel,comb ined with the on-site rockburst phenomenon,to explain the accuracy of the above determination,and on this foundation The related rockburst control ways are given.