Research On The Optimum Design Of 3D Pilot-hole Trace In HDD

Trenchless Technology or No-Dig is a new construction technology that laying new pipeline, replacing or repairing old pipeline under the condition of no or little digging the earth's surface, by utilizing various measure technical method of rock and soil drilling and oriented monitoring and control.The trenchless technology is a high and new developing technology on recently,and an important extended technology of Exploration Engineering.As the complication of underground pipelines in garden city and the Advocate of encouraging protecting of the environment against pollution,Pilot Drilling technology is more and more important in the using of city underground pipelines and pilot-hole trace design.But construction requirement is also harder and harder.It is a key technology of Pilot Drilling sitting pipeline that accurately control the boring trace position to avoid obstruction and accurately and successfully sit the pipeline.So, pilot-hole trace design is not only gist of pilot-hole construction,but also standard of checkout the construction quality.The feasible,appropriate and optimized of the scheme of pilot-hole trace design not only relate to the difficulty and cost,even the success of construction,but also is potent guarantee of appropriate allocating the underground resources.Now,the universal design method of pilot-hole trace is the model of "gradient line-curve-horizontal line-curve-gradient line". This model can't design the 3D pilot-hole trace reasonably on the condition of complex underground pipelines,or the flexural strength of drilling hole due to ignoring of soil character effect on job site.These entire make that the design trace is divorced from real trace and result in rationality and maneuverability of design trace badly.The author has made a research and discussed on the theory of guide strength and the method of 3D pilot-hole trace optimized design in this article,as following:1.The research of guide strength theory and laboratory test and analysis.On the base of ignoring the effect of rock breaking by water jet,I have analyzed the stress status of drill bit in pushing detailed.The essential mechanism of drilling-hole bending is the soil under inclined plane will occur part shear failure due to supporting biggish press,and the soil is compelled extrusion under the drilling bit.Because of vertical stress component of press stress on inclined plane,the soil on the drilling bit topside will occur compression deformation. So,the guided strength depends on the soil of drilling bit topside and underside strain weight. Founded the basic equation of evaluating the Guided Strength related with soil character: F_z·L_b=M_r(G_s)+F_t(G_s)·l_t(G_s)As the particularity of rock and soil material,and existent constitutive equations about soil material can't project the specialty of real soil.So,it is very difficult to accurately evaluate the guide strength.This report founded the analysis formula of calculating the guide strength and the theory in material mechanics and more mature limit bearing capacity theory of soil mechanics. The formula includes factors as:outer diameter(D_r),inner diameter(d_r)and elastic ratio(E_r) of drilling rod;diameter(D_b),length(L_b),angle(α)and size(W & L)of inclined plane of guide bit;body weigth(γ),cohesive strength(c),friction angle(φ),elastic ratio(E_s),possion's ratio(μ)of soil and depth(D)of guide bit.The result of calculation shows that the formula for guide strength is right contrasting to the real value.In addition,the design of a set of laboratory test and analysis simulation facility can analyze the various factors of influencing guide strength quantitatively.Through the laboratory tests,I can obtain the effect degree of the drilling tool and soil characteristics on guide strength.The test data is the reliable basis and guarantee for the calculation theory of guide strength.2.The fundamental research of 3D pilot-hole trace optimization design.The guide strength is a very important parameter for the pilot-hole trace design.And it not only lies on the guiding ability of drilling tool,but also depends on the guiding ability of soil on job site.Moreover,the design value of guide strength G_sdalso meets the ultimate bending strength of drilling rod and pipeline safe working.Combining the factual engineering,I founded the method of confirm the designed value of guide strength G_sd: G_sd=G_s≤min([i_rs],[i_ps],[i_cp],...)On the base of research about confirming the design value of guide strength,I suggest the pilot-hole trace 3D simulate design and control point aptitude design.I analyze and acquire the evaluate model of linear drilling trace,guide bend trace by push bit,control point aptitude design method and evaluate model on complex underground pipeline and complex 3D pilot-hole trace conditions.3.The development of 3D pilot-hole trace visualization software design.On the base of research for guide strength and hole trace optimization design theory,I have developed software whose name is 3D Simulation and Aided Design System of the Pilot-hole Trace in HDD by making the use of Visual C++ development software and OpenGL 3D graph library.The software can carry out 3D visualization about landform,physiognomy,buildings, stratums,underground pipelines and barriers,job pit,hole trace and so on,And it can build pure three-dimension quantified construction model.The major pilot-hole trace function is designed by simulating and emulating control method and control point aided method that meet the rock and soil property,position of underground pipeline and drilling tool and device characteristics. During the process of design pilot-hole trace,the program can achieve guide strength evaluate and adjust automatic,and also offers the tactics of instructional guide of steering control.In addition,the software has visualized and lifelike 3D visualization viewport model and 2D quantify viewport model,which can carry out designing and operating by all orientation.Its operation mode is convenient GUI.The addenda function is much universally,such as Excel and AutoCAD files automatic identifying and importing,detail design data,design chart,print output and so on.The appropriate application of computer and 3D visualization technology on pilot-hole trace design is not only more visual,fast and appropriate design the hole trace,and provides a fire-new design conception and operating platform for the optimum design of HDD pilot-hole,but also has an important scientific significance for layout,construction,manage,check and accept, information storage of trenchless engineering.