The Study And Application Of "Planting-bar" Anti-floating Rock Bolt

With the number and depth of foundation of high-rises increasing, the anti-floatability of underground structuress becomes more and more prominent. Nowadays, four kinds of anti-floating methods applied in practical projects are basically weight-matching, water-draining with stake-cutting, anti-floating stake and anti-floating bolt. Among them, anti-floating bolt is widely used for its advantage of low-cost, short construction time, steady structure and high safety performance. However, as anti-floating bolt is too long and grouting is difficult under the pressure of flowing water, its applicatin in projects is rather limted The paper chiefly poses a new type of anti-floating bolt ----"planting-bar"anti-floating rock bolt to deal with groundwater buoyancy. It conbines the technology of planting-bar with that of anti-floating bolt, and can solve effectively the problems with anti-floating bolt mentioned above. Meanwhile, with the advantage of shallow borehole, construction convenience, ease of pore-forming, low-cost, short construction time and low consumption in building materials, it has greater potential for development.The paper makes a detailed ananysis and study of the pullout resistance mechanism of anti-floating bolt. Based on the analysis, the paper introduces planting-bar technology and gives a systematic description of its working mechanism, concoction of anchorage substance, construction techniques and so on. The detailed studies are as follows.(1) Carry out theoretical study and derivation of the working mechanism of"plant-bar"anti-floating rock bolt and stress transmission mode between anchor bolt and ground, and formulate mechanical model of anchoring ability that affects anchor bolt. Analyze systematiclly the effect that such factors can have on the anchoring capacity of anchor bolt as bolt material, bolt length, anchoring depth, bolt layout, anchorage substance, bolt roughness, installation techniques of anchor bolt, and so on,(2) On the basis of analyzing the present studies and features of inorganic anchorage substance, develop the anchoring material applied in anti-floating rock bolt and carry out on-the-spot and indoor modeling experiments on the performance of anchoring materials. By comparison with anti-floating stake and organic glue planting-bar construction, establish the relationship between pullout resistance capacity and influencing factors like maintenance time, anchoring depth and anchorage substance.(3) In terms of numerical calculation, apply FLAC(Fast Lagrange Analysis of Continua) numberical simulation calculation to the study of working mechanism of"plant-bar"anti-floating rock bolt, and formulate corresponding calculation models. Analyze the differenct working mechanisms between single bolt and multiple anchor bolts, and make a comparative study of the calculation results in various working conditions.(4) Make a study of the field construction techniques and technology of"planting-bar"anti-floating bolt, and take the project using"plant-bar"anti-floating rock bolt as an exmple to illustrate its application in anti-floating elementary construction and make a comparison with other anti-floating measures to show its substantial economic and social benefits.