Development And Application Of Directional Drilling And Soil Squeezing Effect Based On Hole Expansion Theory

With the rapid development of national major engineering projects,urban land resources are increasingly scarce.How to reduce the impact of engineering construction on dense urban environment is a problem worth studying.The horizontal directional drilling construction technology has the obvious advantages that does not occupy land and does not affect traffic etc.It plays a very important role in the construction of pipeline and pipe network infrastructure in our country.But horizontal directional drilling also has its disadvantages in the construction process,that is,the squeezing effect caused by directional drilling in the process of hole reaming has adverse effects on the surrounding environment.It is of great significance to estimate the squeezing effect of directional drilling and reaming effectively so as to reduce the influence on embankment safety and underground pipeline.At present,finite element numerical simulation is the main method to study the effect of directional drilling,reaming and squeezing.On the basis of studying and analyzing the theory of pore expansion,this paper takes engineering examples as the background to analyze the effect of pore expansion and earth squeezing by using the derived theoretical formula,and further solves it by using finite element numerical simulation.On the one hand,it further verifies the accuracy of pore expansion theory in analyzing the effect of directional drilling and earth squeezing.On the other hand,the distribution law of soil displacement change and stress change caused by directional drilling,expanding and squeezing effect is expounded.The main research work and achievements include:(1)The theory of pore expansion is applied to study the squeezing effect of directional drilling and reaming.The calculation method of pore expansion theory is summarized and the calculation method of cylindrical pore expansion theory based on Tresca failure criterion and Mohr-Coulomb failure criterion is expounded.(2)Taking engineering examples as the background,using the calculation method of the theory of hole expansion,the theoretical analysis and calculation of the effect of directional drilling,hole expansion and earth squeezing are carried out.It is found that the radial displacement and radial stress of the excavation show logarithmic attenuation along with the increase of the radial distance,and the closer the distance to the pipeline,the more severe the attenuation.It is found that the influence range of radial displacement and radial stress increases with the increase of reaming aperture.(3)Using the same engineering example as the background,the finite element numerical simulation analysis,obtained the radial displacement and stress distribution law,and compared with the theoretical analysis,the radial displacement and radial stress influence range is basically the same,further proves that the hole expansion theory can be applied to the analysis of directional drilling and soil squeezing effect.(4)For the influence of directional drilling and reaming,prevention and remedial measures are proposed in this paper.Since the soil around the pore is deformed due to the effect of reaming and squeezing,the friction resistance of the pipeline is large in the process of backtowing,resulting in secondary deformation of the soil.Therefore,in order to reduce the friction resistance of the pipeline back towing,a pipe rust removal device is invented,which is suitable for pipes of different sizes.And realized automatic operation to ensure the quality of pipeline rust removal.Figure [40] table [4] reference [59]...