Force transmission characteristics for the non-equidistant arrangement thrust systems of shield tunneling machines

Earth Pressure Balance shield tunneling has been successfully adopted for urban tunneling and has resulted in increases in working speed, savings of man-hours and improved safety. Based on the ellipse eccentricity, the ellipse matrix equation for non-equidistant systems has been constructed. Through the analysis of the matrix, the characteristics of force ellipse eccentricity were investigated in detail. The distinction from the equidistant system was studied by applying the force ellipse to the thrust systems of shield machines in engineering applications. It provides a new arrangement for the thrust system hydraulic cylinders, under large change-of-direction forces or uneven geological bodies, which may prevent the segments from cracking due to an over-offset load.     

Determination of the cutterhead torque for EPB shield tunneling machine

Cutterhead torque is an important parameter for the design and operation of earth pressure balance (EPB) shields. Based on the analysis of several completed project cases from job sites, the conventional torque determination model based on experimentation proves rough enough to be improved. Composition and corresponding calculation method of cutterhead torque are presented, taking into account of cutterhead structure, cutting principle and the interaction between cutterhead and soil. Considering a Φ1.8 m EPB test machine in the lab, theoretical calculation following the improved model and test are carried out with three typical types of soils. Calculation and test results indicate that the cutterhead torque varies with geological conditions apparently, and the opening ratio of the cutterhead as well as earth pressure turns out to be the two most important factors in determining the cutterhead torque. The test results also show that the torque calculation formula for EPB shield tunneling can reasonably predict the excavation torque required by the cutterhead in clay soil tunneling, but for cohesionless tunneling, soil conditioning reduces the amount of torque necessary.     

Electro-hydraulic proportional control of thrust system for shield tunneling machine

In this paper, a thrust hydraulic system of shield tunneling machine with pressure and flow compound control scheme is proposed. In the control system, the task of real-time measuring of the pressure and the displacement of hydraulic cylinder in each thrust group is accomplished by pressure sensor and displacement sensor respectively, forming the closed-loop pressure and speed control with proportional valves. Thrust system mathematical modeling including hydraulic system and multi-cylinder acting dynamics is presented. Synchronization motion control between cylinders is also achieved by means of master–slave PID with dead band compensating displacement error. Experiments of thrust pressure and speed control as well as cylinder synchronization are conducted on the shield simulation test rig. The experimental results show that the proposed thrust hydraulic system and its control can meet the requirements of tunneling.     

Research on characteristics of deformation in thrust system for EPB shield machines

The purpose of the research is to investigate into characteristics of deformation in thrust system which reduces the stiffness with the increase of displacement for piston in hydraulic cylinder. Firstly, based on the hyperstatic compatibility, the spatial deforming ellipse for the driving system has been discovered. Then the characteristics for the deforming ellipse of even and non-uniform arrangement systems have been analyzed in detail. Finally, applying deforming ellipse to the thrust systems of a shield machine in engineering applications, the characteristics of the deforming ellipse affected the behavior of the thrust system have been discussed. The result could provide a theoretical foundation and support for the design of thrust systems in shield tunneling machines.     

无水砂卵石地层盾构推力及刀盘转矩的计算

以无水砂卵石地层盾构施工为例，运用理论和经验公式对盾构推力和刀盘扭矩进行了计算和比较，对相同或相似地层条件下的盾构参数计算和选型具有一定的参考价值。     

Experimental study on slurry-induced fracturing during shield tunneling

Facial support in slurry shield tunneling is provided by slurry pressure to balance the external earth and water pressure. Hydraulic fracturing may occur and cause a significant decrease in the support pressure if the slurry pressure exceeds the threshold of the soil or rock material, resulting in a serious face collapse accident. Preventing the occurrence of hydraulic fracturing in a slurry shield requires investigating the effects of related influencing factors on the hydraulic fracturing pressure and fracture pattern. In this study, a hydraulic fracturing apparatus was developed to test the slurry-induced fracturing of cohesive soil. The effects of different sample parameters and loading conditions, including types of holes, unconfined compressive strength, slurry viscosity, and axial and circumferential loads, on the fracturing pressure and fracture dip were examined. The results indicate that the fracture dip is mainly affected by the deviator stress. The fracturing pressure increases linearly with the increase in the circumferential pressure, but it is almost independent of the axial pressure. The unconfined compressive strength of soil can reflect its ability to resist fracturing failure. The fracturing pressure increases with an increase in the unconfined compressive strength as well as the slurry viscosity. Based on the test results, an empirical approach was proposed to estimate the fracturing pressure of the soil.     

Thrust force allocation method for shield tunneling machines under complex load conditions

Thrust system is one of the most important subsystems in the shield tunneling machines. Multiple hydraulic cylinders in the thrust system provide the required thrust force and help to overcome the large load torque in the excavating process, which is a typical over-actuated mechanical system. Therefore, load distribution among thrust cylinders will be uneven in the face of large load torques, which is the primary cause of cracks in lining segments. To handle this problem, most of the existing works focus on thrust system layout optimization for a predetermined geological condition. Consequently, the optimization results cannot adapt to varying thrust load conditions. We aim to provide a more flexible solution for this problem by using a reconfiguration strategy based on a force-on-off principle, which can dynamically determine whether a cylinder in the thrust system outputs force or not. Illustrative examples show that the reconfigurable thrust system ensures more even force distribution among thrust cylinders under varying thrust load conditions compared with the traditional thrust system and does not require extra hardware cost, which verifies the flexibility and effectiveness of the proposed method.     

泥水盾构在富水砂层中带压进仓技术

以南昌地铁1号线穿越赣江区间泥水盾构在上软下硬（上部砂层,下部泥质粉砂岩）富水砂层中成功的带压进仓经验,讲述泥膜形成技术、保压计算方法、气密性测试、带压进仓安全注意事项、减压出仓恢复性措施等,并分析带压进仓过程中可能出现的泥膜破坏修复措施、漏气保压困难等紧急情况的,提出应对措施,为类似工程提供借鉴。     

Experimental study of the effect of conditioning on abrasive wear and torque requirement of full face tunneling machines

One of the main operational parameters in pressurized full face soft ground tunneling with machines such as earth pressure balance (EPB) TBMs is soil conditioning. Soil conditioners which are proper foam or conditioning agents, are often injected through the cutterhead or into the cutting chamber to make the muck flowable, lower inner friction between the soil particles, control soil stickiness, prepare the excavated soil to be compressible during the tunneling operation, control the water inflow, reduce the torque on the cutterhead, and lower power and torque of the screw conveyor. Foams can also be used in hard rock tunneling to reduce the wear and torque to replace conventional dust suppression by water sprays. This paper reviews the common practice in soil conditioning and focuses on assessing the influence of the conditioning on tool wear and torque requirement of the machines. Tests performed on many standard type soils and few samples from soft ground tunneling projects around the US on Penn State Soil Abrasion testing device. The results of tests performed in dry, moist and conditioned soil will be discussed and compared in this paper. The preliminary results show that the use of proper soil conditioning can reduce the wear of cutters and machine components by orders of magnitude while it can reduce the torque by over 50%.     

地铁盾构下穿公路的影响分析

基于城市发展的实际情况,以广州14号地铁线为例,分析了采用盾构施工对其现有道路地基及桩基的影响,并结合数据模拟软件,模拟了盾构穿越过程中对路基沉降的影响,为该项目的安全施工及使用提供了保证。     

Dimension optimization of an orientation fine-tuning manipulator for segment assembly robots in shield tunneling machines

This study focuses on the dimension optimization of a three-DOF orientation fine-tuning manipulator for segment assembly robots in shield tunneling machines. An index is introduced to evaluate the effectiveness of the motion/force transmissibility of the manipulator. The orientation capability of the manipulator is analyzed, and the corresponding indices for orientation capability are then defined. On the basis of performance atlases, the process of determining optimum geometric parameters is presented for the purpose of high orientation capability and good motion/force transmissibility.     

盾构施工变形的智能预测与控制

根据目前地下工程学科发展的现状以及盾构法隧道施工的实际问题，提出了智能控制理论研究盾构法隧道施工系统的变形预测的常用方法：人工神经网络和模糊控制理论，并分析了这两种方法研究的基本理论，对实际施工有着重要的意义。     

关于次梁作用于主梁上的扭矩问题的探讨

本文通过工程实例 ,分析了次梁作用于主梁上的扭矩引起主梁抗剪扭箍筋超筋的问题 ;并提出了对此类问题的处理办法。     

浅谈盾构孤石段地层掘进技术

结合深圳地铁11号线宝安站至碧海站区间采用土压平衡盾构法施工实例,简单介绍了孤石地层掘进的难点和风险,主要介绍遇到孤石后判别孤石和处理孤石的办法,并有针对性地将该方法应用于地铁施工中。     

A method for detecting and pretreating boulders during shield tunneling in granite strata

Bulletin of Engineering Geology and the Environment - Boulders are spheroidal and weathered rock fragments that exist in softly weathered granite strata. Boulders can cause severe damage to the...     

Koch曲线的Hausdorff测度的改进上界估计

通过构造更加精细的新覆盖,得到新覆盖与Koch曲线的交集对应的连通弧,并利用相关定理计算出Koch曲线的Hausdorff测度更好的上界估计值.     

基于单片机的盾构推进控制系统的研究

根据盾构推进系统控制的特点,提出了基于单片机P87C52X2的推进控制系统,并应用芯片GM8154解决了该系统I/O不足的问题,最后给出了整个系统的软硬件的设计.     

盾构掘进工程概预算折旧方法探讨

通过对目前概预算编制中盾构掘进工程折旧现状的分析,提出了四种盾构掘进工程概预算折旧方法,根据不同方法探讨了其适用范围,为概预算编制中合理计列盾构机的折旧费用提供指导.