Modelling the performance of EPB shield tunnelling using machine and deep learning algorithms

This paper introduces an intelligent framework for predicting the advancing speed during earth pressure balance(EPB)shield tunnelling.Five artificial intelligence(AI)models based on machine and deep learning techniques-back-propagation neural network(BPNN),extreme learning machine(ELM),support vector machine(SVM),long-short term memory(LSTM),and gated recurrent unit(GRU)-are used.Five geological and nine operational parameters that influence the advancing speed are considered.A field case of shield tunnelling in Shenzhen City,China is analyzed using the developed models.A total of 1000 field datasets are adopted to establish intelligent models.The prediction performance of the five models is ranked as GRU>LSTM>SVM>ELM>BPNN.Moreover,the Pearson correlation coefficient(PCC)is adopted for sensitivity analysis.The results reveal that the main thrust(MT),penetration(P),foam volume(FV),and grouting volume(GV)have strong correlations with advancing speed(AS).An empirical formula is constructed based on the high-correlation influential factors and their corresponding field datasets.Finally,the prediction performances of the intelligent models and the empirical method are compared.The results reveal that all the intelligent models perform better than the empirical method.

Regulating bulkhead pressure of EPB shield machines through DEM modeling and data mining

Proper regulation of the earth pressure on the bulkhead of earth-pressure balanced(EPB)shield tunneling machines is significant to ensure safe construction.This study proposes a procedure for regulating the bulkhead pressure by combining numerical simulations and data mining,and applies the procedure to a metro line constructed in sandy pebble stratum using EPB shield.Firstly,the relationship between the bulkhead pressure and the pressure on the tunnel face is carefully obtained from discrete element modeling,and the required supporting earth pressure is derived by considering the arching effect.Secondly,aided with the machine learning method,a model is constructed for predicting the average bulkhead pressure per ring according to the operational parameters(i.e.,the average driving speed and the rotation speed of the screw conveyor).Given the target value of the bulkhead pressure,the optimal values of the operational parameters are obtained from the model.In addition,an autoregressive moving average stochastic process model is developed to monitor the real-time fluctuation of the bulkhead pressure and guide the actions taken in time to avoid dramatic fluctuations.The results indicate that the pressure difference between the tunnel face and the bulkhead is considerable,and the consideration of the arching effect can avoid overestimating the bulkhead pressure.A combination of the machine learning model and the stochastic process model provides a plausible performance in regulating the bulkhead pressure around the target value without dramatic fluctuation.

双模(EPB/TBM)盾构模式转换技术工程实践

双模盾构机为地质起伏变化较大的盾构隧道工程而设计,通过对平衡模式的切换来适应不同地质环境下盾构的高效施工掘进。深惠城际平湖站至凤岗站区间因具有前段、后段为上软下硬地质,中段为全断面岩层地质的特点而采用EPB/TBM双模盾构施工,其间,需要切换模式4次。文章就盾构机模式切换的方法进行系统的阐述。

Numerical investigation on the spewing mechanism of earth pressure balance shield in a high-pressure water-rich sand stratum

The spewing of a screw conveyor easily occurs from the earth pressure balance(called EPB)shield in a water-rich sand stratum.This may lead to the collapse of the tunnel face and even serious subsidence of the ground surface.To understand the spewing mechanism of the shield screw conveyor and explore the critical hydraulic condition of soil spewing in a shield–soil chamber,a simplified theoretical model for the spewing of the screw conveyor was developed based on the equation of groundwater flow in the screw conveyor under turbulent state.Thus,coupling Darcy's law with Brinkman's equation,this model was implemented within the COMSOL Multiphysics framework.The underground water flow in the shield screw conveyor was simulated so as to obtain its velocity and flow rate.Numerical simulations show that the water pressure distribution is concentrated in the lower part of the soil chamber after the groundwater enters the soil chamber.When the groundwater enters the screw conveyor,its pressure gradually decreases along the direction of the screw conveyor.When the water flow reaches the stratum–shield interface,the flow velocity changes markedly:first increases and concentrates at the entrance of the lower soil chamber,plummets and stabilizes gradually,and increases again at the exit.The soil chamber and screw conveyor are significantly depressurized.It is also found that the soil permeability coefficient can be reduced to k<2.6×10^(−4)cm/s through appropriate soil improvement,which can effectively prevent the occurrence of spewing disasters.

EPB/TBM双模盾构复合地层掘进参数及适应性研究

研究目的:为探究EPB/TBM双模盾构在复合地层中的掘进适应性,本文基于深圳地铁12号线怀德站—福永站及13号线留仙洞站—中间风井区间的EPB/TBM双模盾构施工案例,对比分析不同掘进模式下的掘进参数和能源消耗情况的变化规律,以期为类似工程提供参考。研究结论:(1)双模盾构在软土地层采用EPB模式保证掌子面稳定,硬岩地层采用TBM模式规避掘进速度低及刀具磨损等风险;(2)掘进参数变化规律在软土段EPB模式下表现为“低转速、高扭矩、高推力”,硬岩段TBM模式表现为“高转速、低扭矩、低推力”;(3)微风化岩层TBM模式的推进速度较EPB模式在中风化岩层提升了38%,有效掘进时长占比提升约106.7%;(4)双模盾构能源消耗较软土地层EPB模式并未明显增加;(5)本文研究可为双模盾构在复合地层中的掘进适应性提供参考。

Earth pressure balance control for EPB shield

This paper mainly deals with the critical technology of earth pressure balance (EPB) control in shield tunneling. On the assumption that the conditioned soil in the working chamber of the shield is plasticized, a theoretical principle for EPB control is proposed. Dynamic equilibrium of intake volume and discharge volume generated by thrust and discharge is modeled theoretically to simulate the earth pressure variation during excavating. The thrust system and the screw conveyor system for earth pressure control are developed based on the electro-hydraulic technique. The control models of the thrust speed regulation of the cylinders and the rotating speed adjustment of the screw conveyor are also presented. Simulation for earth pressure control is conducted with software AMESim and MATLAB/Simulink to verify the models. Experiments are carried out with intake control in clay soil and discharge control in sandy gravel section, respectively. The experimental results show that the earth pressure variations in the working chamber can be kept at the expected value with a practically acceptable precision by means of real-time tuning the thrust speed or the revolving speed of discharge system.

EPB盾构螺旋输送机的参数多目标优化

为了提高EPB盾构螺旋输送机的输送效率,减小输送机螺旋体的磨损并降低运输过程中的功率损耗,结合离散元软件EDEM、NSGA-Ⅱ优化算法和熵权TOPSIS法,提出一种盾构用螺旋输送机结构参数优化方法。通过离散元软件EDEM按照设计好的正交试验进行仿真,得到输送机的质量流率、螺旋体平均磨损量和运行功率性能指标,并对仿真的可靠性进行验证。利用Matlab软件将仿真得出数据进行拟合,建立多个结构参数间的性能指标函数。采用NSGA-Ⅱ算法对螺旋输送机参数进行优化,得到Pareto前沿解集,并由熵权TOPSIS法确定最优解。结果表明:当螺旋输送机安装倾角为24.69°,螺距为613.25 mm,螺旋内径为696.34 mm,螺旋轴径为211.88 mm时,输送机整体性能最好,其他条件相同的情况下,质量流率提高了10.56%,螺旋轴磨损量减小了8.64%,功率损耗降低了6.41%。研究结果对EPB螺旋输送机的设计改进有一定的参考价值。

Influence factors and calculation model of the adhesion strength of clayey soil for EPB shield tunnelling

When earth pressure balance (EPB) shield tunnels are constructed through clayey ground, the soil adheres to the cutter, cutterheadand chamber bulkhead due to the high adhesion strength between the steel and the clay, thus clogging the shield. To investigatethe influence of different factors on the adhesion strength, this study used montmorillonite, kaolin and mixtures of the two as testsoils. The adhesion strength between the steel and clay is determined with a customized rotary shear apparatus. The results showthat when the consistency index of the soil specimen is less than 1, the adhesion strength between the steel and clay increaseswith the consistency index. As the consistency index decreases, the effect of the normal pressure on the adhesion strength graduallyweakened. As the contact angle of the shear plate increases, thus reducing the hydrophilicity, the adhesion strength decreases. Whenthe soil specimens with different plasticity index values have the same consistency index value, the adhesion strengths are similar.The adhesion strength increases gradually with increasing surface roughness. Based on grey incidence analysis, the order of thefactors affecting the adhesion strength is as follows: normal pressure > consistency index > contact angle > plasticity index ≈ surfaceroughness. The normal pressure, consistency index and contact angle all have important effects on the adhesion strength betweensteel and clay. However, because there are no large differences in the contact angle among the metal materials, the approximateadhesion strength can be calculated by considering the effects of only the normal pressure and consistency index. Themeasures thatare effective for preventing EPB shield clogging are increasing the soil softness and decreasing the hydrophilicity of the cutterheadby applying new materials for the cutters and cutterhead.

基于协同学的双模盾构TBM-EPB施工复合系统协同性评价模型研究

以深圳地铁13号线双模盾构施工问题分析为基础,引入协同学理论,建立双模盾构施工子系统协同的序参量方程,应用熵权法计算各序参量的权重值,寻找影响双模盾构施工体系效率和效益提高的主导因素,构建双模盾构施工复合系统协同模型,并应用协同度对此模型进行评价。结果表明:双模盾构施工过程中,盾构机子系统、围岩子系统与环境子系统之间未出现不协同的情况,这说明双模盾构施工技术与深圳地区的复合地层具有较强的适应性。但是由于EPB模式段地层较软弱,围岩变形与地表沉降较大,协调度相对于TBM模式段较低。应用协同学理论,建立双模盾构施工复合系统协同评价模型,可得出某一区间段盾构机、围岩与周围环境之间协同水平的综合测度,为施工过程相互作用状况的空间比较和发展趋势提供参考。

基于深度学习的盾构机土舱压力场预测方法

土舱压力是盾构机受力状态和掌子面稳定等核心问题中的关键因素。土舱压力具有显著的空间变异性,其形成演化机制源于装备与岩土之间的复杂耦合作用,与地质特征、掘进参数等多源参数相关。然而,现有土舱压力预测方法一般未考虑空间分布特征或地质参数影响。针对该问题,提出了一种基于空间分布物理特征函数导引深度学习的盾构机土舱压力场预测方法。该方法构建物理特征函数用于解耦土舱压力空间分布特征,采用卷积神经网络和门控循环单元分别提取多源参数历史信息的空间特征和特征系数的时序特征,结合多源参数实时信息对特征系数进行预测,从而实现土舱压力场的预测。以长沙地铁四号线某区段为案例,利用该方法准确预测了土舱压力空间分布实测数据,准确率高达0.98,验证了所提方法的有效性。敏感性分析表明,不同地层中土舱压力空间分布特征系数的主要敏感参数基本一致,但其敏感度随地层地质条件的变化规律差异显著,可为复杂地层盾构机土舱压力精细化调控提供参考。

富水砂层土压平衡盾构渣土改良技术研究

富水砂层土体具有流塑性差、渗透性强的特点,土压平衡盾构施工时易造成排土困难和喷涌事故。针对西安地铁10号线穿越富水砂层的土压平衡盾构工程,采用膨润土泥浆和泡沫剂改良盾构渣土,提出了改良渣土流塑性的评价方法,基于其流塑性和渗透性确定最佳改良方案,为工程提供借鉴和参考。结果表明:(1)当改良渣土塌落后无开裂或坍塌、塌落形状为梨形、塌落度为180~210 mm、塌落渣土与地面接触角θ为0°~90°时,流塑性合适,此时改良渣土的渗透系数于90 min内稳定在10-5cm/s,满足工程要求;(2)最佳改良方案为:渣土、膨润土、水三者质量比保持在200∶1∶40~200∶1.5∶44之间,泡沫剂溶液体积比浓度为2%,泡沫注入比为6%。

基于S7-400H的EPB盾构盾尾密封系统软件设计

利用S7-400H PLC冗余系统平台开发、设计土压平衡(EPB)盾构控制系统软件,能够进一步提高系统的容错能力;对盾尾密封系统的控制及使能条件的关联进行分析、总结,给施工过程中盾构操作及维修人员以指导;对盾尾密封系统的控制流程进行分析,给盾构控制系统软件设计人员以帮助。

EPB盾构机推进系统振动响应分析

盾构机推进系统可以看作一个振动系统,为了研究土压平衡式(earth pressure balance,EPB)盾构机推进系统对初始条件的振动响应,用模态迭加法推导了无阻尼系统对初始条件的振动响应计算公式,在此基础上考虑地基弹簧的影响建立了五自由度无阻尼EPB推进系统振动模型,并推导了该振动模型对初始条件的振动响应.分析算例振动响应得出了绕X轴和Y轴的初始角度对推进系统的姿态影响很大.当初始角度为1°时,盾构机推进系统就会发生高达27.53°的偏转,这样对盾构机姿态角的调整会产生很大的挑战,甚至会使盾构机偏离计划路线太多无法完成掘进工作.研究结果对工程上EPB盾构机掘进过程中姿态角调整具有一定理论指导意义.

EPB盾构机土仓压力分布有限元数值模拟

结合某地铁施工实例,采用有限元方法数值模拟了土压平衡盾构机的土仓压力。通过计算刀盘开口率不同的土仓压力分布,建立了盾构机土仓的承压隔板压力与开挖面压力的关系,研究了刀盘开口率对盾构机土仓压力分布的影响。通过回归分析,得到刀盘开口率与压力传递系数之间的映射关系。数值模拟结果表明,有限元模拟结果与现场观测值基本一致。

EPB盾构泡沫系统设计缺陷与改进

通过对现有EPB盾构在掘进过程中泡沫系统存在的缺陷进行分析与研究,提出了详细的改进设计思路与措施,从而极大地降低了土压平衡盾构在掘进过程中发生堵塞的概率,提高了盾构的掘进速度,具有一定的实用和推广价值。

水泥稳定盾构渣土的收缩性能研究

针对土压平衡(earth pressure balance,EPB)盾构渣土的资源化再利用问题,开展水泥稳定EPB盾构渣土作为路用材料的收缩性能研究,主要通过干缩试验及温缩试验进行评价。结果表明,EPB盾构渣土的干缩系数在前31天变化明显,温缩系数则随着温度的升高呈现波动性上升趋势;水泥掺量的增加不仅会影响EPB盾构渣土体积对温度、水分变化的敏感程度,还会进一步增强温度对体积的影响;与常用的水泥稳定碎石相比,EPB盾构渣土受掘进工艺影响缺少大粒径骨料的嵌挤作用,因而收缩性能较差。因此,在EPB盾构渣土施工过程中不仅需要严格控制水泥用量,还应掺入些许骨料调整其级配。

复杂环境下城际铁路大直径双模盾构选型技术及应用

为研究复杂地质环境下大直径双模盾构选型技术及应用效果,以深大城际机场东站—黄麻布站区间为依托,首先分析了该区段的工程重难点和施工风险,结果表明:该区间需穿越长距离硬岩地层和部分软土地层,下穿多处重要建构筑物和穿越多条构造破碎带和节理密集带,施工风险高、难度大。因此,为兼顾盾构机在硬岩地层的掘进效率和软土及不良地质条件下的地层稳定,综合选用EPB(earth pressure balance)/TBM(tunnel boring machine)双模盾构机,并根据施工重难点对盾构机结构和功能系统进行了针对性设计。最终,对该盾构的现场工程应用进行了效果评价。结果表明:所选的EPB/TBM双模盾构能较好地满足工程需求,确保了盾构机掘进的安全性和高效性。研究成果可为其他类似条件下的双模盾构机选型提供参考和指导。

Experimental study on workability and permeability of sandy soils conditioned with thickened foam

Water spewing and muck plugging often occur during earth pressure balance(EPB)shield machines tunnelling in water-rich sandy strata,even though the conventional foam has been employed to condition sandy soils.In this study,a novel thickened foaming agent suitable for EPB shield tunnelling in water-rich sandy strata is developed.In contrast to conventional foam-conditioned sands,the thickened foam-conditioned sand has a low permeability due to the consistent filling of soil pores with the thickened foam,and the initial permeability coefficient decreases by approximately two orders of magnitude.It also exhibits a suitable workability,which is attributed to the enhanced capability of the thickened foam to condition sandy soils.In addition,the effect of concentration on the stability of the foam is explained by the Gibbs-Marangoni effect,and conditioning mechanisms for the thickened foam on sands are discussed from the evolution of foam bubbles.

二次调节技术在盾构EPB模拟系统惯性能回收中的应用

提出一种基于二次调节技术的盾构土压平衡系统,系统制动过程中调节二次元件的排量作泵工况,在螺旋输送机的惯性带动下向系统回馈能量。模拟实验表明,这种基于二次调节技术的盾构土压平衡系统能取得明显的惯性能回收效果,系统能量回收效率受二次元件的排量、系统油源压力及转速等参数的影响,在能量回收过程中实行恒转矩控制能使系统制动过程平缓,并能满足制动时间等要求。

EPB盾构机工作面土压力和油缸推力合理优化

基于Rankine的主动和被动土压力理论,采用解析方法建立了合理确定EPB盾构机工作面压力方法,给出了EPB(Earth Pressure Blance)盾构机随埋深和土体力学参数的变化关系。根据力的平衡原理,推导了EPB盾构机推力与盾构机埋深、土体力学参数和盾构机几何尺寸的解析表达式。数值计算结果表明,所提出的推力计算方法与现场实际采用的数值基本一致。