复杂岩石地层隧道掘进机操作特性分析

为提高掘进效率,改进掘进机与地层的匹配性设计,对掘进机的操作特性进行研究。基于重庆越江隧道盾构掘进试验,分析复杂岩石地层盾构刀盘扭矩、刀盘推力及转速的参数选用原则,在此基础上,分析主掘进参数与切深的关系。随后,对不同地层条件下刀盘扭矩与推力之间的匹配性进行分析,绘制了刀盘扭矩与推力之间的操作特性曲线,并用于分析和制定不同地层条件下的主掘进参数匹配方案。对于较软的泥岩,刀盘扭矩先达到最大值,而推力却不能发挥其最大能力;岩石强度增高,所需推力增加,在发挥扭矩能力的前提下,推力也能发挥其功能,从而使二者达到最佳操作关系;若岩石强度过高,推力保持在最大值,但切深很浅,滚刀旋转阻力减小,刀盘扭矩很难发挥最大能力。因此,应视地层软硬,根据刀盘推力与扭矩的操作特性对刀盘的主掘进参数进行合理设计,并在掘进过程中实时调整其匹配关系。     

盾构刀盘扭矩对风化岩地基中邻近桩基的影响

基于地铁盾构施工对邻近某客运站桩基影响的问题,利用FLAC^3D有限元模拟分析软件,通过八种工况对比分析了刀盘扭矩与盾构推力对风化岩地基中邻近桩基的影响。结果表明:刀盘扭矩与盾构推力对桩基的影响呈现不同的规律。刀盘扭矩对桩基的影响规律主要为:盾构刀盘扭矩的存在使得桩身主要产生沿隧道横向的附加弯矩和位移,桩身沿隧道纵向的附加弯矩和位移相对较小;桩身最大弯矩和最大水平位移均发生在隧道中心线附近。与刀盘扭矩的影响不同,盾构推力主要使桩身产生沿隧道纵向的附加弯矩和位移;但桩身最大弯矩和最大水平位移也发生在隧道中心线附近。在风化岩地基中,刀盘扭矩对桩基沿隧道横向的影响是不可忽略的。     

复合地层盾构掘进参数及其与地层相关性分析

盾构掘进参数在复合地层中比在单一地层中的变化更为复杂,不同地层条件下掘进参数差异性很大。为了研究复合地层中盾构掘进参数与地层的相关性,本文以深圳地铁11号线车公庙站~红树湾站和南山站~前海湾站两个区间Φ7m复合式土压平衡盾构施工为背景,针对区间典型地段的不同地层,采用数理统计方法分析了5个关键盾构掘进参数与6种主要地层的相关性。结果表明：不同地层中的总推力的平均值差异不大,为1320.94~1697.33t,但硬岩地层中总推力的波动性最大,最小值为789.38t,最大值达到1994.52t|不同地层中的推进速度的平均值差距较大,其中在花岗岩差异风化和硬岩地层中推进速度平均值最低,约为20mm/min|硬岩中的刀盘扭矩的平均值明显高于其他地层,最高可达5倍,而其余地层差距不大,平均值为608.93~822.27kN·m|各地层中刀盘转速的离散性较小,平均值差异不大,为1.5~1.9r/min|不同地层中贯入度的平均值差距较大,最高可达40mm/r,花岗岩差异风化和硬岩地层中最低,约为12mm/r。本文研究成果可为同类型盾构在复合地层条件下掘进参数的选取和优化提供指导。     

盾构隧道施工盘形滚刀推力分布规律研究

 盾构掘进时,刀盘由油缸推压到工作面上,滚刀与岩石之间产生相互作用。为研究各滚刀推力分布规律,分析影响滚刀与岩石相互作用的影响因素,指出掘进过程中滚刀推力分布主要与岩石刚度有关。假设滚刀与岩石弹性点接触,建立刀盘与岩石相互作用的三维弹性支点力学模型并进行了简化,运用有限元方法对其进行分析与比较。研究表明,刀盘上各滚刀的推力分布并不均匀,滚刀布置稀少处的推力较高,面刀推力均比边刀推力高出40%～60%。相同的刀盘形式,滚刀布置方式不同,其推力分布差异较大。最后,运用蒙特卡罗有限元方法,分析岩石刚度变化对滚刀推力分布的影响,岩石越软,滚刀推力分布越均匀;反之,滚刀推力分布的均匀性越差。在硬地层中掘进时,个别推力高的滚刀磨损严重,换刀频繁,影响了施工进度。因此,该部位的滚刀布置值得进一步研究。     

Disc cutter wear prediction for a hard rock TBM cutterhead based on energy analysis

Disc cutter wear is a crucial problem that influences the working efficiency and security of hard rock tunnel boring machines (TBMs). This wear results from friction energy accumulation and conversion. In this study, the process of hard rock TBM disc cutter wear is identified and analyzed by quantifying the collective energy change. This study starts with an analysis of the friction process between the disc cutter and hard rock. The relationship between the rolling force work and thrust force work of the disc cutter is examined. As a result, the disc cutter energy equation is determined, and the meaning of the upper and lower bounds of this equation are discussed. Based on the above results, the hard rock TBM cutterhead energy equation is then deduced. A method to identify the friction work is developed. According to the energy wear theory, the cutter wear law on hard rock for a TBM cutterhead is revealed, and a method for predicting disc cutter wear for a hard rock TBM cutterhead is advanced. Furthermore, the validity of this prediction method is confirmed by utilizing data from project cases.     

复杂岩石地层盾构掘进效能影响因素分析

基于现场掘进试验和岩石点荷载强度试验,对泥岩、砂岩交互地层条件下泥水盾构的掘进效能及其影响因素进行研究.利用现场采集的数据,运用回归分析的方法,主要分析盾构掘进效能与岩石强度、刀盘推力及刀盘扭矩的关系.研究成果表明,岩石强度越高,刀盘每转切深和掘进速率就越低,二者呈幂函数曲线关系;随着刀盘推力的增大,切深呈幂函数关系增加;而随着刀盘切深的增加,刀盘扭矩则呈线性增加.对比两种地层的掘进特性,相对而言,泥岩地层掘进效能较高,但需要较大的扭矩,而在砂岩地层掘进需要较大的推力才能获得理想的掘进效能.     

Discrete element model for performance analysis of cutterhead excavation system of EPB machine

With the aim of probing for design theory of cutterhead excavation system of earth pressure balance (EPB) machine, the parameters representing the system performance are concluded firstly. Then a 3D model for cutterhead excavation system of EPB machine is presented with the discrete element method (DEM) software PFC^3D, which is capable of simulating the tunneling ground in site, the machine structure and the excavation operation. The performance parameters indicating stability of excavation face, soil discharging rate, cutterhead system torque and cutter wear are measured by running the DEM code. The results obtained with the DEM model are accord with situ data. It indicates that the DEM model is a promising method replacing the field experiment to analyze the influences of the structural parameters on system performances, which are essential for structure optimization design of the cutterhead system of EPB machine.     

上软下硬地层盾构机滚刀磨损特性研究

以广州地铁某盾构区间为工程背景,结合上软下硬地层的强度特性,提出了硬地层所占面积与掌子面面积之比来评估上软下硬地层中地层分布情况的方法,确定硬地层对开挖面强度特性的影响。根据地层特性和分布情况,提出了适应不同均一地层的刀盘合理转速以及适用于上软下硬地层的刀盘设计转速。通过监测盾构机掘进过程中的刀盘扭矩变化,提出根据刀盘扭矩变化幅度制定刀盘转速调整时机的预警机制,实现刀盘转速提前调整。结合实际应用效果,上软下硬地层会使盾构滚刀产生过快磨损,超前调整刀盘转速可有效降低滚刀受冲击荷载的影响,延长滚刀正常工作时的掘进距离,显著提高上软下硬地层中盾构施工效率。     

不同刀具配置下隧道掘进机高效破岩机理与推力预估

为解决隧道掘进机刀盘刀具破岩的安全性、可靠性、高效性这一隧道掘进机施工难题,从高效破岩机理和刀盘刀具与围岩耦合作用规律两个方面进行了研究,对单刀及多刀破岩理论体系进行了完善。结合理论分析和滚刀岩机作用综合实验台上的实验结果,提出了红砂岩、石灰岩和花岗岩等3种常见岩石的最优破岩刀间距,并给出了当岩石强度位于40～170 MPa之间时的最优刀间距计算式。综合考虑各种因素对隧道掘进机总推力、刀盘扭矩的影响,提出了复合式隧道掘进机总推力、刀盘扭矩估算的理论公式。通过工程实例验证,该理论计算式具有较高的科学性和精确性。研究成果可直接用于刀具选型布置、推力、扭矩设计,从而降低隧道掘进机的制造成本、提高施工效率。     

高强度围岩隧洞TBM刀具磨损规律研究

刀具磨损是影响TBM掘进效率的重要因素,该文以北疆供水二期工程XEVIII标段隧洞为依托,开展高强度围岩条件下刀具磨损规律研究。该标段已掘进段围岩强度最大为160MPa,平均为120MPa。根据掘进过程中的刀具磨损统计资料,分析不同刀位的刀具磨损值、围岩强度和掘进参数对刀具磨损的影响以及不同掘进参数对刀具磨损的敏感度,结果表明：中心滚刀和正面滚刀的累计磨损量随安装半径增大呈指数式增长,边缘滚刀累计磨损量受安装角度影响,随安装半径增大先增大后减小;边缘滚刀的单刀磨损量最大,正面滚刀次之,中心滚刀最小;随着围岩强度提高,中心滚刀和正面滚刀每延米磨损量呈指数型增长,边缘滚刀每延米磨损量呈二次函数型增长,所有刀具每延米累计磨损量呈线性增长;围岩强度不变时,随着刀盘转速、刀盘扭矩、推力、贯入度增大,刀具每延米磨损量均呈二次函数型变化,先增大后减小,随着掘进速度增大,刀具每延米磨损量呈二次函数型变化,先减小后增大;刀具磨损对刀盘扭矩和推力最为敏感,为减小磨损,建议施工中将刀盘扭矩控制在1100～1300kN·m或2100～2400kN·m,将推力控制在9000～11000kN或15000～16000kN。     

Prediction of geological characteristics from shield operational parameters by integrating grid search and K-fold cross validation into stacking classification algorithm

This study presents a framework for predicting geological characteristics based on integrating a stacking classification algorithm (SCA) with a grid search (GS) and K-fold cross validation (K-CV). The SCA includes two learner layers: a primary learner's layer and meta-classifier layer. The accuracy of the SCA can be improved by using the GS and K-CV. The GS was developed to match the hyper-parameters and optimise complicated problems. The K-CV is commonly applied to changing the validation set in a training set. In general, a GS is usually combined with K-CV to produce a corresponding evaluation index and select the best hyper-parameters. The torque penetration index (TPI) and field penetration index (FPI) are proposed based on shield parameters to express the geological characteristics. The elbow method (EM) and silhouette coefficient (S_i) are employed to determine the types of geological characteristics (K) in a K-means++ algorithm. A case study on mixed ground in Guangzhou is adopted to validate the applicability of the developed model. The results show that with the developed framework, the four selected parameters, i.e. thrust, advance rate, cutterhead rotation speed and cutterhead torque, can be used to effectively predict the corresponding geological characteristics.     

Thrust and torque components on mixed-face EPB drives

In this communication we propose a method to estimate net thrust and torque applied at the excavation front by cutting tools from EPB machines when they are working in mixed faces constituted by soils and soft rock. The method is inspired by similar simplifications used for the analysis of TBM drives in rock. The proposal is validated using a database of EPB registers which were gathered from more than 35 km of tunnel drives excavated in soils, soft rock and heterogeneous media. The results allow us to assess the influence of the type of ground excavated and its geotechnical properties on the net thrust and torque applied.     

盾构施工过程中的土体变形研究

 基于盾构施工过程,利用弹性力学Mindlin解,通过坐标变换经积分推导刀盘与土体之间摩擦力所引起的地面变形计算公式,并得到盾构施工引起的总地面变形计算公式。结合杭州地铁一号线工程中具有代表性的粉砂土层,分析盾构与土体的复杂相互作用,并对盾构与土体相互作用引起的土体变形特征进行计算。通过计算发现,盾构施工中盾壳摩擦和正面推力是盾构推力设置的主要因素,而刀盘与土体摩擦是刀盘扭矩设置的主要因素,盾构前方土体隆起主要由盾壳摩擦引起,刀盘摩擦作用主要引起地表沉降的非对称分布,地表沉降主要由盾尾空隙产生。通过实例计算并与实测结果对比发现,使用盾构变形计算公式适用范围在盾构机头前后±2L距离处,对指导实际盾构施工具有重要意义。     

Realtime prediction of hard rock TBM advance rate using temporal convolutional network (TCN) with tunnel construction big data

Real-time dynamic adjustment of the tunnel bore machine (TBM) advance rate according to the rock-machine interaction parameters is of great significance to the adaptability of TBM and its efficiency in construction. This paper proposes a real-time predictive model of TBM advance rate using the temporal convolutional network (TCN), based on TBM construction big data. The prediction model was built using an experimental database, containing 235 data sets, established from the construction data from the Jilin Water-Diversion Tunnel Project in China. The TBM operating parameters, including total thrust, cutterhead rotation, cutterhead torque and penetration rate, are selected as the input parameters of the model. The TCN model is found outperforming the recurrent neural network (RNN) and long short-term memory (LSTM) model in predicting the TBM advance rate with much smaller values of mean absolute percentage error than the latter two. The penetration rate and cutterhead torque of the current moment have significant influence on the TBM advance rate of the next moment. On the contrary, the influence of the cutterhead rotation and total thrust is moderate. The work provides a new concept of real-time prediction of the TBM performance for highly efficient tunnel construction.     

长大煤矿斜井TBM刀具磨损影响因素与规律研究

TBM刀具的磨损是影响TBM施工效率的重要因素。以TBM掘进中的围岩磨蚀性、围岩强度、刀盘转矩和刀盘转速为研究对象,研究了长大煤矿斜井施工过程中TBM刀具磨损的影响因素和规律。依托国内首条TBM施工的神华神东补连塔煤矿斜井工程,通过对掘进过程中现场数据的实时监测,获取了刀具单周磨损量、围岩磨蚀性、围岩强度、刀盘转矩和刀盘转速等技术指标。研究结果表明,在其他因素参数一样的条件下,TBM刀具的单周磨损量与围岩的磨蚀性CAI值、强度基本呈线性关系。刀具的单周磨损量随围岩强度和磨蚀性的增大而增大。而当刀盘扭矩和刀盘转速增大时,刀具的单周磨损量先增大后减小。     

高强度基岩爆破预处理泥水盾构掘进特征研究

泥水盾构在高强度基岩地层中掘进,盾构自身刀具无法有效破岩,采用基岩爆破预处理的控制钻爆法能严格控制破碎碴块体量,提高刀具破岩能力,但盾构施工过程中,掘进参数与岩石之间关系非常复杂。以台山核电站取水隧道为背景,对现场获得的工作数据进行挖掘,分析基岩爆破前后地层中盾构刀盘推力、刀盘扭矩及掘进速度的参数的选用特点。在此基础上,引入参数转换量FPI、TPI指数及比能进行研究,研究表明,未经处理基岩地层,岩石强度过高,刀盘推力先达到最大值,但切深很浅,扭矩很难发挥最大能力;经爆破处理后,基岩岩体受到不同程度破碎,盾构机推力及扭矩能有效发挥其功能,掘进效能提高。因此,在盾构机的工作负荷范围内,应依据基岩岩体破碎效果,调整刀盘推力和扭矩,使之更好地适应地层,力争达到高效安全的掘进目的。     

基于长短时记忆网络的盾构机刀盘扭矩实时预测

盾构机是土质隧道开挖的优质工程机械,被广泛应用在地铁建设。刀盘扭矩是保证盾构正常推进的关键参数,能被精确实时预测对预防灾难事故、确保施工正常推进具有极高的指导意义。针对现有扭矩预测多为计算平均值的问题,提出一种基于长短时记忆(Long-Short Term Memory,LSTM)网络的扭矩实时预测模型。首先通过分析盾构机状态参数与扭矩的相关性,选择一组关键状态参数,降低输入维度;然后建立LSTM扭矩预测模型;最后利用该模型在归一化后的实际数据集上进行验证并与BP网络模型对比。试验结果表明,该模型在测试集上均方差为0.002 81,平均绝对误差为0.036 7,均优于BP网络;该模型具有良好的预测能力与泛化性能,能够很好地拟合关键状态参数与刀盘扭矩之间的非线性关系。     

软土地层土压平衡盾构施工参数的模型试验研究

我国沿海经济发达城市及一些内陆中心城市正在兴建或筹建地铁,这些地区的地下广泛分布着较厚的软黏土沉积层。为研究土压平衡盾构在这种软土地层中施工的适应性,以上海地铁M8线某区间隧道工程为研究背景,采用室内模型试验的方法,开展在不同埋深、不同刀盘开口率、不同推进速度以及不同螺旋机转速等情况下的盾构掘削模型试验。通过对试验结果的整理与分析,得出土仓压力与排土效率、单位时间排土量与推进速度、推力和扭矩之间的内在联系,以及隧道埋深、刀盘开口率、推进速度对推力和扭矩的影响。这些结论的取得为盾构施工参数之间及其与地层特性之间的适应性理论提供了有益的帮助,并为更好地指导软土地层盾构隧道的设计与施工服务。     

Experimental study on working parameters of earth pressure balance shield machine tunneling in soft ground

Deep sedimentary deposits of soft clays are widely distributed in coastal areas as well as many interior major cities in China. In order to study the stratum adaptability of earth pressure balance (EPB) shield machine tunneling in such types of soft ground, model tests of tunneling excavation, using the running tunnel of the Shanghai Metro Line M8 as a background, are carried out with different over burden ratios, opening rates of cutter head, driving speeds and rotation speeds of screw conveyor. Based on the test results, the interrelationships between chamber pressure and mucking efficiency, mucking rate and driving speed, thrust force and torque are obtained. The influences of tunnel depth, opening rate of cutter head and driving speed on thrust force and torque are revealed. Such findings can not only facilitate establishing relationships between shield working parameters and soil properties, but also serve as a guide for the design and construction of shield tunnel in soft ground.     

盘形滚刀切割岩碴粒径分布规律研究

 岩碴大小及粒径分布是联系机械掘进参数与岩石性质的重要指标。依据盘形滚刀切割岩碴形成机制,分析岩碴尺寸组成及形成特点。基于现场掘进试验,按不同岩性和掘进机不同推力水平,分组获取岩碴试样,对其进行尺寸量测与筛分试验,取得大量的岩碴尺寸数据,并运用概率统计理论对泥岩、砂岩的岩碴尺寸进行分布拟合检验;随后对实测岩碴粒径分布进行计算并与理论分布模型(对数正态分布函数和Rosin-Rammler分布函数)进行对比分析。在岩碴尺寸分布、粒径分布及其与机械参数的关系等方面取得一些有益的结论,对改进掘进机设计及提高掘进效能具有一定的参考意义