Study On Mechanical Characteristics And Optimization Of Shield Cutterhead In Calcareous Nodule Stratum

With the continuous development of subway transportation,it is more and more popular.In subway construction,shield tunneling has the advantages of little impact on the surrounding environment,high automation,high quality and efficiency,safety,and environmental protection.The shield cutter head is the key component to realizing shield tunneling.Due to the complex and changeable geotechnical structure in China,there are many problems that the cutter head does not adapt to the soil in the process of tunneling.Among them,calcareous concretion is not only a stratum with extremely unstable mechanical properties but also an accident-prone stratum.Therefore,it is of great practical significance to study the tunneling characteristics of the shield cutter head based on the calcareous concretion stratum.Based on the engineering background that the shield machine in a section of Zhengzhou Metro Line 10 passes through the calcareous nodule stratum,with the help of cutting theory and ABAQUS finite element software,this paper studies the stress characteristics of the shield cutter head,cutting tools and the adaptability of the calcareous nodule stratum in the construction process,and puts forward the optimization measures of the shield cutter head and cutting tools according to the simulation results,to improve the load distribution of the cutter head,reduce tool wear The goal of improving shield tunneling efficiency.The main research contents of this paper are as follows:(1)This paper introduces the general situation of engineering geology in the section,analyzes the causes,characteristics,and distribution of calcareous nodule soil summarizes the basic criteria of cutterhead design and cutting theory of cutting tools and explores the geological adaptability of cutterhead tools.(2)Based on the geological characteristics of the project,the three-dimensional simulation model of the shield cutter head and soil is constructed,and the cutting load calculation theory of the cutter head is introduced to simulate the tunneling process of the shield cutter head in calcareous nodule stratum,and the variation laws of tangential,normal load and torque of cutterhead are obtained,Firstly,the mechanical response of cutter head structure in different content of calcareous nodule soil layer(calcareous nodule soil,weak calcareous nodule layer,and complete calcareous nodule layer)is compared and analyzed.Finally,the mechanical response of the cutterhead under different driving parameters such as cutterhead rotation speed and propulsion speed in the complete calcareous nodule layer is compared and analyzed.(3)The three-dimensional model of the cutter and soil is established,and the change law of the cutter cutting force is obtained by analyzing the simulation results.Firstly,the mechanical response of the cutter in the soil layer with different content of calcareous nodules is compared and analyzed.Finally,the mechanical response of the cutter under the condition of different cutting depths and rake angle of the cutter in the complete calcareous nodules layer is compared and analyzed.According to the simulation results of cutterhead,aiming at the problems of uneven distribution of cutterhead load,serious tool wear,and low tunneling efficiency,the layout of shield tools is optimized based on Archimedes spiral method;Establish the evaluation standard of tunneling efficiency,optimize the tunneling parameters,and put forward the advancing speed and rotating speed of cutterhead suitable for this working condition;Increase hob assisted shield tunneling to improve the geological adaptability of cutters;At the same time,the measured values of cutter head tool wear before and after optimization are compared to verify the simulation results,to provide theoretical guidance for the construction of shield tunneling through calcareous nodule stratum.