Research On Surrounding Rock Dynamic Perception And Boring Parameter Aided Decision-making Method Of TBM Tunnels

With the sustainable development of economy,the continuous improvement of comprehensive national strength and the successive application of high-tech,tunnel and underground engineering in China has developed rapidly as never before.The method of tunnel boring machine(TBM)with many advantages of fast tunneling speed,small construction disturbance,superior tunnel quality,high comprehensive socio-economic benefits,safety and environment,etc.is taken into account to be applied in an increasing number of tunnel project.In the traditional boring of TBM,generally,the surrounding rock conditions are qualitatively judged and then the boring parameters are adjusted by human experience,the parameters are difficult to better match the surrounding rock conditions,resulting in low boring speed,large cutter wear,and even serious consequences such as landslides.Consequently,perceiving surrounding rock conditions and optimizing excavation parameters exert vital guiding significance for the safe,efficient and economical construction of TBM.In view of the above hot issues,based on a water supply project in the northwestern areas of China,a surrounding rock dynamic perception and boring parameter aided decision-making method of TBM tunnels are proposed in this paper,which are successfully applied in practical engineering.The primary research contents,achievements and innovations are summarized as follows:(1)Based on field investigation and laboratory test,the geological conditions relying on the project and the main performance parameters of TBM machine are determined.the change laws of boring efficiency are analyzed and the boring state of TBM are studied.The distribution and length of the designed surrounding rock classification and the exposed surrounding rock classification are compared,the distribution and change laws of boring parameters are analyzed and the main reasons affecting boring efficiency are determined.Boring samples are selected by grouping and the data are statistically analyzed,then relatively reasonable range of rotation per minute of cutterhead and total thrust under manual experience control are preliminarily obtained.Results indicate that it is difficult to inform the surrounding rock conditions of the excavation face and adjust the boring parameters in time during the process of TBM boring,and the boring parameters such as the total thrust and rotation per minute of cutterhead selected by the driver under the same geological conditions are inconsistent,resulting in a marked difference in boring efficiency under the similar surrounding rocks.In order to maintain the efficient and economic boring state of TBM for a long time,it is necessary to obtain the strength,integrity and other parameters of the rock mass of the excavation face as much as possible,and understand the range of the corresponding control parameter of efficient boring under different surrounding rock conditions.(2)The rock uniaxial compression strength and rock mass integrity coefficient are obtained through comprehensive integrated approaches of laboratory test,field test and field reconnaissance.The grading parameters of rock slag and vibration parameters of cutterhead are obtained by image recognition and vibration monitoring,and the data set including the rock uniaxial compression strength and rock mass integrity coefficient,grading parameters of rock slag and vibration parameters of cutterhead is established.The influence of the surrounding rock parameters on grading parameters of rock slag and vibration parameters of cutterhead are studied,respectively.The perception model of the surrounding rock parameters is established by integrating the grading parameters of rock slag and the vibration parameters of cutterhead,which is subsequently optimized by secondary learning.Results indicate that the grading parameters of rock slag and the vibration parameters of cutterhead display certain correlation with the surrounding rock parameters.The perception model of the surrounding rock parameters integrating the grading parameters of rock slag and the vibration parameters of cutterhead is capable of accurately predicting the rock uniaxial compressive strength and rock mass integrity coefficient with the average absolute percentage errors of 0.046 and 0.082,respectively.(3)The data sets including surrounding rock parameters,boring parameters and boring efficiency are established through the approaches of dynamic perception,laboratory test and field test,and the effects of surrounding rock parameters and boring parameters on boring speed and average rock-broken volume of single cutter are analyzed successively.Based on the existing prediction model,a prediction model of boring efficiency with the surrounding rock classification is developed.Ultimately,with the goal of “high efficiency and low consumption”,a boring parameter aided decision-making model of boring parameters is established,and the recommended value range of rotation per minute of cutterhead and total thrust under different surrounding rock classes is obtained.Results indicate that the changes of surrounding rock and boring parameters impact the penetration rate and average rock-broken volume of single cutter of TBM.The average absolute percentage errors of prediction of the penetration rate and average rock-broken volume of single cutter by the prediction model of boring efficiency based on the surrounding rock classifications is less than 0.1.With the goal of“high boring speed and low cutter wear”,the Pareto optimal solution set of boring parameters is obtained by using the multi-objective particle swarm optimization.During the practical process of boring,the appropriate boring strategy must be selected by adjusting the exertion coefficient of boring speed regarding the progress and cost requirements of the project.(4)The surrounding rock dynamic perception and boring parameter aided decision-making method of TBM tunnel is established,the engineering application of such method is conducted on the test sections of XE Tunnel.Results indicate that the method is feasible to input the vibration parameters of cutterhead,the grading parameters of rock slag and more indexes obtained by collecting cutterhead vibration and rock slag images into the perception model of surrounding rock parameters,output the information such as surrounding rock class,rock uniaxial compression strength and rock mass integrity coefficient,and then input the above information together with the tested rock quartz content into the boring parameter aid decision-making model to acquire the optimal solution set of boring parameters.By setting up the exertion coefficient of penetration rate,find the corresponding solution in the optimal solution set of boring parameters,and output the total thrust and rotation per minute of cutterhead recommended by the method.Using the boring parameters recommended by this method,the penetration rate and average rock-broken volume of single cutter are increased by 15.6% and 4.5%,respectively.In the section with model application,boring stagnation or abnormal machine damage of TBM caused by improper selection of boring parameters never occurs,verifying the feasibility and effectiveness of the surrounding rock dynamic perception and boring parameter aided decision-making method,which can provide a reference for the improvement of boring efficiency of the similar tunnel projects with TBM.