Study On Deformation Mechanism And Application Of Full Length Anchor Under Coupling Effects Of Temperature And Pressure

As the depth of mining increases,the phenomenon of high ground temperature and high pressure appears.And the bolt support of deep mine roadway has encountered new problems,which is mainly manifested in the support of soft rock roadway in deep mine.Due to the coupling effect of high ground temperature and high pressure,it is difficult to install resin anchoring agent for full-length anchoring,the anchoring interface is easy to be damaged and the anchoring body is easy to fail.All of theses problem have a serious impact on the safety production of the mine,which needs to be studied and solved urgently.Therefore,this paper takes the deep soft rock roadway support engineering of Dingji Coal Mine in Lianghuai mining area as the research background.The stress deformation mechanism and application of full length anchor under the coupling effect of temperature and pressure are studied under the high ground temperature and high pressure conditions of coal mine deep mine roadway.In this paper,preparation test,indoor pull-out test,numerical simulation,similar model test and field engineering application are used to systematically study the material preparation and performance improvement of full-length anchoring agent,the failure mechanism of anchoring interface,the stress transfer law of anchorage unit body and the interaction mechanism between anchor bolt and surrounding rock,the main research contents and results are as follows:(1)In view of the problems of the existing full-length anchoring resin anchoring agent,such as high anchoring resistance,difficult installation,poor heat resistance and low strength,a new type of full-length anchoring agent with good heat resistance,high strength and suitable consistency is developed through a large number of preparation tests,which improves the performance and solves the technical problems of full-length anchoring construction and support.The mixing ratio of the new anchoring agent is as follows:mixed resin:coarse stone powder:fine stone powder:accelerator:curing agent:KH-570=100:275:275:1:32.5:1,in which the mixed resin ratio is PET type:fx-470 type=30:70.(2)The cementing time test equipment for resin anchoring agent was developed to simulate different temperature environment.It can accurately measure the gelation time of different types of anchoring agent in different environment,which provides the basis for the design of bolt installation technology in underground.(3)Through the pull-out test of anchorage interface under the coupling effect of temperature and pressure,the results show that:under the same temperature conditions,with the continuous improvement of surrounding rock strength,the ultimate pull-out force and residual anchoring force of anchorage interface gradually increase;under the same surrounding rock strength condition,with the continuous increase of temperature,the ultimate pull-out force and residual anchoring force of anchorage interface gradually decrease;the axial force of anchor rod is non-linear distribution along the anchoring direction and decreases gradually along the anchoring depth and the interfacial shear stress gradually transfers to the anchorage end with the increase of pull-out load.With the increase of surrounding rock stress,the plastic zone of anchorage interface layer transforms from radial splitting failure to longitudinal shear failure.The failure modes of anchorage interface are divided into shear slip failure and shear dilatancy slip failure.The failure mechanism of anchorage interface under temperature and pressure coupling is obtained.(4)The pull-out test system of temperature confining pressure loading is developed,and the load transfer law of anchorage unit under different support forms,temperature and confining pressure is also studied in this paper.The results show that with the increase of temperature,the ultimate bearing capacity of the anchoring unit decreases.The axial force of the free section of the bolt is basically the same,and the loss of the axial force transmission is small.When the axial force is transferred to the junction of the bolt and the resin anchorage agent and enters the anchoring section,the axial force of the bolt decreases sharply.Secondly,the influence of confining pressure on the distribution of axial force and interfacial shear stress is studied by numerical simulation.Based on the test and numerical simulation results,the load transfer law of the whole anchor under the coupling effect of temperature and pressure is obtained.(5)Through the similar model test method,the supporting effect of full-length anchoring and end anchoring under the coupling effect of temperature and pressure are studied.The results show that,under the same temperature and surrounding rock pressure,the convergence of surrounding rock of full-length anchoring support is small,and the fracture development position of surrounding rock is shallow.The stress distribution of roadway surrounding rock is monitored by strain sensors and optical fiber sensors arranged in the model.The results show that the tensile compressive stress zone of surrounding rock of roadway with different support methods is different,and the tensile stress zone of surrounding rock with end anchorage is more widely developed.The results show that the axial force distribution is more uniform and the stress concentration degree is small at the anchor tray,which reveals the interaction mechanism between the bolt and surrounding rock.(6)Based on the composite bearing mechanism of anchor and solid,the calculation formula of anchoring support parameters for surrounding rock of deep roadway is derived,and the method to determine reasonable preload and anchorage length is given.According to the engineering conditions of the central air return roadway in West No.3 mining area of Dingji Coal Mine,the support design optimization is carried out,and the supporting parameters such as the optimized support mode,the row spacing between the bolts,the anchorage length,the preload and the mixing time of the anchoring agent are obtained.The engineering application and field monitoring results show that the convergence of the optimized support scheme is obviously less than that of the original scheme,and the convergence of the roof and floor and the two sides is divided 24.2%and 20.2%respectively and also achieves a good supporting effect.Figure[116]table[29]reference[165].