| Tunnel anchor ingot has the remarkable characteristics of strong bearing capacity,economy and environmental protection.Due to the lack of research on tunnel anchor at home and abroad,there is also a lack of design calculation formula of tunnel anchor bearing capacity in relevant design specifications.The existing tunnel anchor design had been basically verified and inverted based on in-situ test results.In this paper,tongzi River bridge is taken as the engineering background and the research object.By means of in-situ scale model test,parameter inversion,numerical simulation and other comprehensive methods,the mechanical and deformation characteristics,rheological characteristics,ultimate bearing capacity and stability of tunnel anchor in soft bedded rock area of mountainous area are systematically studied.The main research work and conclusions of this paper are as follows:(1)In-situ scale model tests have been carried out for tunnel anchors of Tongzi River Bridge.The test conditions mainly include design load test,overload test and creep test.The test results show that: The whole surrounding rock and the model anchor have been in a stable state under the design load(1P),3.5p and 7P load,and the maximum deformation under the load of 1P,3.5p and 7P is 0.22 mm,0.55 mm and 3.5mm,respectively.The creep characteristics have been not obvious under 1P load,and the creep stage of constant rate only appears under 7P load,but it is still stable creep.When the load reaches 10 P,the top of the anchor plug and its surrounding rock are damaged,and the anchorage system is in the form of tensile plastic failure,but the concrete of the anchor plug is still in elastic working state.(2)based on the in-situ test results for the parameter inversion simulation,inversion to have got the physical and mechanical parameters of surrounding rock of argillaceous siltstone and creep parameters,and the field experiment results close to the value,and the model close to anchor and calculation model of rock mass stress conditions,to a certain extent,this group of value can reflect the actual situation,to verify the effectiveness of the creep of inversion,However,the calculated displacement shows that the overall displacement is larger than that of the in-situ test,indicating that the in-situ test results are more safe and reliable.(3)The test results of the model anchor in the in-situ model test and the inverted elastic-plastic parameters have been used to conduct fine modeling of the tunnel anchor in the mountainous argillous siltstone,and the morh-Coulomb model and ubiquitous Joint model are analyzed.The main stages of analysis include construction stage,design load stage,overload stage and creep stage.The simulation results have shown that the ubiquitous joint model was better than morh-Coulomb model to reflect the load-bearing response mechanism of tunnel anchor in layered soft rock in actual mountainous areas.Support measures should be strengthened from excavation to the middle stage of anchor body,and the top support of surrounding rock should be strengthened at the bottom of excavation to ensure construction safety.Under the design load,the maximum deformation is 0.098 mm,and the maximum pulling force of the real bridge anchor can reach 10 P,which can meet the engineering requirements.The creep simulation of 1P,5P and 10 P are all stable rheological,and the anchorage safety meets the requirements under longterm load.Based on the in-situ test and 3d elastoplastic model,the safety factor is 3.5.Considering the long-term bearing requirements of tunnel anchor,the safety reserve factor is 6.Figures 139 Tables 20 References 106... |
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