| Tunnel engineering is a key control project for infrastructure construction such as transportation,water conservancy and hydropower,and involves multiple engineering fields such as highways,railways,urban rail transit,hydropower stations,and inter-basin water transfer.However,the complex and changeable geological environment and many unpredictable factors in the areas where such projects are located have also brought great difficulties to the design and construction of tunnels,in recent years,in order to prevent the occurrence of accidents such as water gushing and mud inrush,landslides and rock bursts during tunnel construction,the use of accurate and fast survey methods is the focus of research on tunnel surveys in recent years,and it is also an important prerequisite for ensuring safe tunnel construction and operation.Therefore,the establishment of highefficiency,environmentally-friendly and safe new survey models,Innovative highprecision tunnel surrounding rock information inversion methods and other core technologies are critical technical problems that need to be solved urgently.At present,horizontal directional drilling(HDD)is a new technology mainly used in trenchless pipeline construction.The pilot hole drilling technology in the horizontal directional drilling technology is now used in the geological survey of long tunnels,that is,a horizontal directional survey hole is first drilled along the tunnel design axis,combined with intermittent coring,hydraulic fracturing,and borehole tv.It can accurately and quickly classify the lithological changes of the surrounding rock of the tunnel,the distribution of the fractured zone,the water inflow status of the tunnel and the grade of the surrounding rock,etc.This thesis takes the geological survey of horizontal directional drilling in Tianshan Shengli Tunnel as the engineering background.First,through the method of theoretical analysis and model test,the concept of mechanical specific energy is introduced by using the measured drilling pressure,torque,rotational speed of the drill bit,drilling speed and other parameters,the quantitative relationship between drilling parameters of horizontal directional drilling and rock strength is studied;Secondly,the lithology of the surrounding rock of the tunnel and the influence range of the fractured zone are accurately divided by analyzing the cuttings,the video data in the hole,the water inflow in the hole and the core obtained twice;Finally,the mechanical specific energy value is calculated according to the drilling parameters corrected in the field,and the surrounding rock of the drilling hole is divided into high energy consumption area and low energy consumption area,In this way,the strength and crushing degree of surrounding rocks in different lithologic intervals can be analyzed,and the results of the in-hole test were compared and analyzed.The main research work and related research results obtained are as follows:(1)A model test system for the correlation between drilling parameters and rock strength of horizontal directional drilling is designed and assembled.In order to make the working characteristics of the test system the same as the actual horizontal directional drilling rig,the test system mainly includes a drilling pressure power system,a rotary power system,and a parameter measurement system.During the test,six parameters of drilling pressure,reaction torque,drilling speed,rotational speed of the drill bit,water pressure and water flow can be collected,which can provide all the parameters required to study the quantitative relationship between drilling parameters of horizontal directional drilling and rock strength.Combined with ABAQUS finite element analysis software,the rock breaking mechanism of the tricone bit was revealed,the stress distribution of the surrounding rock when the tricone bit was drilling in granite was analyzed,and according to the simulation results,the relationship between the drilling pressure,torque and energy consumption of the tricone bit with the drilling depth is analyzed.(2)The influence of drilling pressure and rock strength on the drilling efficiency of horizontal directional drilling is analyzed,a total of 4 sets of tests were carried out in this thesis.The first set of tests used different drilling pressures to drill into six cuboid mortar test blocks with a strength grade of M15 and a size of 300×300×600mm,the influence of different drilling pressures on the drilling speed,counter torque,bit speed,system water pressure and water flow of horizontal directional drilling was analyzed,It is concluded that within the range of the rated working pressure of the positive displacement motor,with the continuous increase of the drilling pressure,the drilling speed and the reaction torque of the horizontal directional drilling also continue to increase,and are proportional to the drilling pressure,while The rotational speed of the drill bit is inversely correlated with the counter torque,the counter torque received by the drill bit is proportional to the water pressure of the system,and the rotational speed of the drill bit is proportional to the water flow;The second and third groups of tests used six and four different strength mortars respectively to study the influence of the uniaxial compressive strength of the mortar on the drilling parameters of the horizontal directional drilling,It is concluded that the drilling pressure and reaction torque of the horizontal directional drilling increase with the increase of the uniaxial compressive strength of the mortar,while the drilling speed and the mortar strength are inversely correlated.Among them,the purpose of the third group of experiments is to avoid the effect of chance on the second group of trials;The fourth group of tests used six natural rocks with different strengths(2 sandstones,2limestones,1 granite and 1 garnet amphibole quartz schist).The purpose of this group of tests is to verify the test results of the mortar,but also to compensate for the influence of rock with higher strength than mortar on drilling parameters,This test shows that the drilling speed has a negative correlation with the rock strength,and the drilling pressure has a positive correlation with the rock strength,but the reaction torque of the rock does not show a gradual increase trend with the increase of the rock strength.(3)Study the quantitative relationship between drilling parameters and rock uniaxial compressive strength,introduce the concept of total drilling energy and mechanical specific energy(MSE),and analyze the quantitative relationship between total drilling energy,mechanical specific energy and rock strength,It is concluded that when the rock strength remains unchanged,the total drilling energy changes in proportion with the drilling depth.When the rock strength increases,the slope of the change curve between the total drilling energy and the drilling depth will also increase,that is,when drilling at the same depth,the rock with high strength consumes more energy;The mechanical specific energy of the horizontal directional drilling increases with the increase of the uniaxial compressive strength of the rock,and the mechanical specific energy of the mortar and the rock is roughly proportional to the uniaxial compressive strength of the rock,and according to the relationship between the two changes Fitting it to the data,when fitting to a linear function,the correlation coefficient is 0.88037,and when fitting to a power function,the correlation coefficient is 0.97124.(4)Analyze the geological survey data of the horizontal directional drilling of Tianshan Shengli Tunnel,firstly,the lithology,the development of joint fissure and Influence range of fracture zone of the tunnel surrounding rock are analyzed in detail by using the data of cuttings,data of borehole tv,water inflow in the hole and coring in the hole;Secondly,the on-site drilling pressure,drilling speed,mud pressure,mud flow and other data are collected,and the bottom-on-bit weight and bit torque of the horizontal directional drilling are corrected according to the weight-on-bit data measured on the ground,and the mechanical ratio is used.The energy consumed by the surrounding rock of the drilling hole in different sections can be divided in detail,and the strength of the surrounding rock of the drilling hole and the sub-range of the broken zone can be judged according to the specific values of the mechanical specific energy corresponding to the high energy consumption area and the low energy consumption area of the drilling hole.etc.,and compared the analysis results of drilling parameters with data such as cuttings XRD analysis,in-hole video,in-hole water inflow,and in-hole coring.The results show that the analysis results of the tunnel surrounding rock strength and the distribution range of the fractured zone by the drilling parameters are basically consistent with the analysis results of the cuttings XRD,in-hole TV and in-hole coring. |
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