Key Problem Research On Calculation And Design Of Scaffolds In Construction Of Unstable Rocks

In China’s western mountains, due to the high mountains and steep, unstable rocksare widely distributed and that is a large high in its management process there are a lotof difficulties and risks. And steel tubular scaffold with couplers as the most commonlyused unstable rock treatment work platform, to research and analysis of its stability, isthe basis of ensuring the safety of unstable rock treatment project. Especially duringdrilling construction, scaffold structure shaking of unstable rock is caused extremelyeasily, even can cause the overall overturning scaffold safety accidents. On the basis ofsummarizing predecessors’ research results, this paper first adopts the research methodof theoretical derivation and numerical simulation to research level of lateral load on theeffect on the stability of the upright tube of scaffolding under vertical load, thencombining with the analysis of mechanical properties of fasteners, the unstable rockscaffolding calculation model under drilling working load are compared and discussed.At last, through theoretical derivation to explore drilling construction under dynamicloading of mechanical properties of scaffolding and its influencing factors, and calculatethe bearing capacity and stability of scaffolding through engineering application. Mainresearch contents and results are as follows：Firstly, Respectively the action of critical load of upright tube of only under thecondition of vertical load, or the condition of horizontal load along with vertical loadwould be derived, and through the ANSYS under the condition of vertical load, lateralload changes in the opposite the influence degree of the upright tube stability sensitivityanalysis. Results show that the horizontal lateral load does not affect upright tube ofunstable rock scaffolding vertical stability of bearing capacity, but the horizontal loadwill cause the additional axial force of upright tube, and as the lateral load increasesgradually, the additional axial force will increase sharply is nonlinear, the upright tubemay be reached before the critical load of the vertical instability and destruction.Secondly, Based on scaffold fastener connection characteristics of scaffolding isdiscussed, by establishing calculation model of Midas Civil under drilling working loadconsidered fasteners "semi-rigid" feature of semi-rigid model and does not consider thefastener "semi-rigid" fully hinged joint model features. After comparison and analysis,found that under the same load condition, the hinged joint model level of node displacement and stress values are larger than corresponding semi-rigid modelcalculation value; But the out-of-plane bending moment of hinged joint modelsignificantly smaller than semi-rigid model calculation values, is to be unsafe.At last, Modal decomposition method is used to solve the analytical solution ofvibration differential equation of unstable rock scaffolding under drilling working load,and according to the obtained scaffold model horizontal displacement value of eachnode for analysis. Then, this paper has discussed the effect of drilling working loadlocation on the stability of the scaffolding through changing the location of drillingworking load. Combination the example of one certain unstable rock of Taibaiyan inWanzhou district, the scaffolding bearing capacity and the overall stability of unstablerock is checking, and working load would be pseudo-static, for even tie membersdeformation calculation.