Support Technology Optimization Of Broken Roadway Based On Loose Circle Theory

With the rapid development of national economy and the increasing demand for space resources,underground engineering construction tends to be a peak.Because of the anisotropic mechanical characteristics of fractured rock mass,the strength of rock mass is small and difficult to support,so the problem of rock mass support is always a difficult problem in the construction of underground engineering.To study the support problem in broken rock mass can promote the future development of underground roadway and chamber to the direction of larger section and longer distance.Therefore,it is of great significance to further study the failure and deformation of broken rock mass,to find out the cause mechanism,the main inductive factors and the relevant supporting methods in the process of roadway instability.Based on the theory of loose ring of surrounding rock,this paper makes a deep study on the support of broken rock mass by means of theoretical analysis,field test,field support investigation and numerical simulation.The research results are as follows :(1)the influencing factors and classification categories of surrounding rock loose zone are systematically expounded and analyzed,and the mechanism of loosening ring theory in roadway supporting process is discussed.(2)Taking a certain iron mine in Xinjiang as the engineering background,the anchor rod drawing test and the surrounding rock loose ring test were carried out in the field,and the tensile pull force of the anchor rod was measured by the anchor rod drawing test.It is found that the data result is less than the theoretical tensile pull force of the bolt,and a main influencing factor of the roadway instability is found.The size of loosening circle measured by experiment is used as the basis to determine the support type of roadway.(3)Through a full investigation of the support situation in the field,it is found that the current support effect is poor,and a large area of collapse,roof fall and other instability phenomena occur in many areas.The main reason for the analysis is the shock load caused by blasting vibration.The mechanical condition of rock mass itself is poor and the support is not timely and unreasonable.(4)According to the measured value of loose ring,the combined support of bolting,spraying concrete and hanging metal mesh can meet the construction requirements.At the same time,according to the stress characteristics of bolt in the support process.This paper introduces the theory of combined arch to calculate and optimize the parameters of support,and obtains a set of supporting schemes suitable for field support construction.(5)Using FLAC3 D numerical simulation software,the equal proportion modeling of mine roadway section is carried out,and the excavation of roadway under different bolting spacing is simulated respectively.It is concluded that the roadway can be effectively stabilized for a long time under the support spacing of 0.7m × 0.8m,which verifies the feasibility of the optimization result of the above support scheme.