| At present,Groundwater pollution in China has shown a development trend from punctate pollution to zonal and planar pollution.As a resule,the in-situ drilling and injection method has become a hot spot.So the Injection Remediation Technology of Dual-tube Guide Drilling was described on the paper to meet the demand of contaminated site remediation.Firstly,based on the investigation,we deem that the horizontal directional well section is more suitable for this technology than the three-section section.Then the bottom hole assembly are designed,which is composited of Φ165mm bit+ Φ150mm dual-tube guide section+Φ92mm packer+Φ114.3mm injection drilling+Φ92mm packer+Φ114.3mm drill pipe+Φ83mm drill pipe.And specific construction techniques are described in the article.In addition,the injection drilling,packer,internal and external drill pipe,bit was designed.And based on the Soilworks of computer3 D design software,the 3D model of each part is established,and the simulation assembly is carried out.Secondly,we concluded that the optimized well spacing is the sum of injection radius and permeation-diffusion radius.And the vertical and horizontal boreholes are arranged in the way of "plum blossom pile".In addition,the theoretical formula of the earthwork quantity of the treated soil was deduced.In addition,the remediation agent transport model was established,and the output dynamic characteristics of ordinary nozzle and Helmholtz nozzle were compared.The results show that Helmholtz nozzle produces stronger natural vibration than ordinary nozzle.Therefore,Helmholtz nozzle with resonant cavity can produce more efficient water jet than ordinary nozzle.Finally,the results show that the optimal target distance is 20-30 mm,and the design target distance is 25.35 mm,the design can make the injection effect is the best.In addition,the optimal erosion parameters are obtained.Therefore the laboratory experiment laid a foundation for the field test of the repair process. |
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