| Tunnel in the process of excavation will produce a lot of surrounding rock pressure,may lead to the overall structure of surrounding rock cracking,surrounding rock deformation,and even lead to tunnel collapse and other serious engineering accidents,so we need to be more careful in the design and construction of the tunnel.Filling karst caves in the karst cave area of tunnel excavation can protect the tunnel more safely and effectively,and filling materials for filling karst caves are also the top priority,which can not only be environmentally friendly and green,but also meet the support requirements,which need further research.River in guizhou province Dou Yun city Yang township poplar hole near the surrounding rock stability of tunnel engineering as the research background,the integrated use of theoretical analysis,numerical simulation and theoretical calculation,the method of the mechanical properties of the cave of the filling material characteristics are studied,it is concluded that the stress and deformation of the surrounding rock in the karst area the influence law of distribution characteristics,so that they can more effectively to fill,More options are added for filling materials of karst caves.Through the embodiment of numerical simulation,it provides a new method and new idea for the filling of karst cave,and also provides guidance for the subsequent practical application.Phosphogypsum,slag and steel slag are used as cementing materials,and quick lime and sodium silicate are used to improve the strength of solid waste filling body.Based on the test results of immersion test and uniaxial compression test,the variation rule of mechanical parameters of solid waste filling body under different proportions was analyzed,and the optimal ratio was finally determined.SEM test was used to observe the optimal ratio,and the reasons for improving the physical performance of the solid waste filling were analyzed from the internal structure characteristics obtained.Using the cloud image obtained from digital speckle test,the change of mechanical properties in the specimen was analyzed.FLAC3D numerical simulation was used to simulate the influence of the distance between the cave and the tunnel,the radius of the cave and the different positions of the cave in the tunnel on the mechanical characteristics of the surrounding rock of the tunnel,including the variation rule of the vertical stress,vertical displacement,shear strain and pore pressure of the surrounding rock of the region.The main conclusions are as follows:（1）Through the test test of the cementing material specimen,it can be concluded that the maximum compressive strength of specimen No.2 is 9.35mpa;The softening coefficient of specimen No.10 is the largest,which is 0.88.The cost of cementitious materials was calculated and compared with the cement used for filling.It was concluded that the cost of cementitious materials at the optimal ratio was reduced by 44%.（2）Through the test and test of the filling body specimen,it can be concluded that the maximum compressive strength is 5.4mpa for solid waste filling body specimen of No.2:35%phosphogypsum,42%slag,12%steel slag,8.5%quicklime and 2.5%sodium silicate.The maximum elastic modulus is 0.566Gpa.The seed setting rate was 99.6%.（3）SEM scanning analysis shows that the waste combination at the optimal ratio can connect and fill the gaps on the solid waste filling body from the microscopic level,restrain the deformation and cracking of the specimen,and improve the compressive strength and deformation resistance of the specimen more effectively.（4）According to the cloud map analysis obtained from the digital speckle test,when the specimen reaches the final failure,the cracks of the specimen run through the whole specimen from top to bottom,and the specimen finally presents the form of shear failure.（5）When the cave is filled,changing the distance between the tunnel and the cave has a small effect on the surrounding rock in the cave area,and the relationship is proportional;Changing the radius size of karst cave has little effect on surrounding rock,which is inversely proportional.Changing the location of karst cave in tunnel has great influence on surrounding rock.Changing the shape of karst cave and filling material has little influence on surrounding rock.By comparing the mechanical properties of surrounding rock before and after filling in karst cave area,the filling body in karst cave can control the pressure brought by surrounding rock more effectively,and ensure the safety and stability of the filling body in karst cave for the tunnel in this region.There are 89 figures,22 tables and 74 references in this paper. |
