| The surrounding rock of soft rock roadway has obvious characteristics of large deformation,high stress,and difficult support.The problem of controlling surrounding rock is very serious.According to the deformation stress state of roadway surrounding rock,the supporting type is designed.It is of great importance to solve the problem of large deformation of surrounding rock in soft rock roadway.The technical system of support design for soft rock is formed according to ground stress and the characteristic of rockmass by geological survey,theoretical analysis,field monitoring and numerical simulation.The main research contents are as follows:(1)The support technology of bolting-shotcreting and U steel combination support network and support backfill of closed-support of section of circular roadway is proposed according to the characteristics of soft rock and horizontal in-situ stress.At the same time,the new supporting parameters and construction technology are determined.The optimization of new supporting parameters has been accomplished by simulating and comparing different bolt spacing,anchoring mode and pre-stressing force anchorage effect.It has been proved that 800mm anchor bolt arrangement spacing,extended anchorage mode and 150kN bolt pretension force is the best in the new supporting parameters.(2)It can be found that the close velocity of roof to floor of roadways is 28.22mm/d for initial type of support.And the close velocity of roof to floor of roadways is 5.334mm/d for new type of support,which is 81.1%lower than initial type of support.Because the roadway tunneling has little disturbance to the surrounding rock,the convergence velocity of two sides of roadways is not very different.The convergence velocity of two sides of roadways is 4.18mm/d and 3.48mm/d respectively.The new support mode is 16.75%lower than the original support mode.The stress of anchor bolt is less than the design value,which proves that anchor bolt has not been damaged.In controlling the deformation of surrounding rock,the supporting effect of the new type of support is better than that of the original support.(3)By comparing the displacement of the roof to floor and two sides of roadways and the distribution of plastic zone in two types of support modes,it has been proved that the new support mode is better than the original support for the deformation of surrounding rock.By analyzing the stress situation of surrounding rock and the stress of supporting structure,it is found that the stress of all supporting systems is consistent with the design value of the scheme.The new support system can effectively resist the influence of surrounding rock and control the deformation and damage of surrounding rock.The support technology of bolting-shotcreting and U steel combination support network has been provided for the support of soft rock roadway of Xiaokang coal mine. |
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