深圳风化花岗岩地层盾构防泥饼渣土改良技术

依托深圳地铁某线盾构工程开展了风化花岗岩地层土压平衡盾构防泥饼渣土改良技术研究。通过对盾构掘进参数和刀具磨损分析,阐述了泥饼对盾构掘进参数和刀具磨损的影响,并结合地层制订了相应的渣土改良方案,有效预防泥饼出现。研究表明:盾构发生"结泥饼"后,推力明显增大,掘进速度逐渐减慢接近0,扭矩变化不大,采用分散剂浸泡刀盘,能消除一部分泥饼,但若渣土改良不合适,泥饼又将会快速形成;盾构结泥饼过程中,滚刀的磨损方式主要是偏磨,且刀具的磨损相对于刀盘回转中心呈现出一定的中心对称性;在风化花岗岩地层中,采用分散性泡沫剂和水可有效提高渣土的流动性,取得理想的改良效果;但在卵石土和风化花岗岩复合地层中,需采用膨润土、分散性泡沫剂和水相结合的渣土改良方案,提高渣土的抗渗性和流动性,且在风化花岗岩与卵石土复合地层和风化花岗岩地层中理想渣土的坍落度值为15～20cm;相比于渣土改良,地层对掘进参数的影响更明显,且盾构在卵石土和强风化花岗岩复合地层中掘进时,推力和扭矩相对较小。     

复合地层泥水盾构掘进参数相关性研究

以南昌市轨道交通4号线在建泥水盾构过江隧道为工程依托,对安丰站—东新站区段泥水平衡盾构掘进穿越不同地层时主要掘进参数的演化规律展开研究,探讨4项主要盾构掘进参数之间的相关性,对盾构总推力、刀盘扭矩、掘进速度以及刀盘转速之间的相关性进行对比分析,最终可以推导出以中风化泥质粉砂岩为主的复合地层条件下泥水平衡盾构掘进参数与不同地层的关系模型,通过一系列现场实时数据对比并进行统计分析,可以发现:掘进速度与盾构总推力和刀盘扭矩呈弱线性相关性;刀盘扭矩和盾构总推力呈弱线性相关性;刀盘转速与掘进速度之间参数取值不存在明显的相关性。     

基于BP神经网络的复合地层盾构掘进参数预测与分析

复杂地质条件下盾构机掘进参数的有效预测可以对盾构施工进行针对性的指导。基于深圳地铁11号线车公庙站～红树湾站和南山站～前海湾站两个区间Φ7m盾构施工现场监测的掘进参数,首先采用BP人工神经网络方法建立了复合地层条件下盾构掘进参数的预测模型|其次,以地层参数为输入组和盾构掘进参数为输出组,通过对数据样本进行训练,得到的输出值基本与原始数据一致,说明该预测模型具有很好的非线性映射能力;最后,采用盾构区间典型地段的地层参数,利用所建立的模型预测了复合地层条件下的盾构掘进参数,预测值与实际数据变化规律相近,平均误差在15%以内。本文建立的BP神经网络模型可用于复合地层条件下同类型盾构掘进参数的预测。     

富水圆砾地层土压平衡盾构掘进参数优化研究

如今盾构法施工在地铁建设中已得到广泛应用,砂卵石、软土等地层的盾构施工技术日趋成熟,而富水圆砾地层的盾构施工技术研究较匮乏。本文依托南宁轨道交通2号线三十三中~苏卢站盾构掘进区间,对富水圆砾地层段和圆砾泥岩复合地层段土压平衡盾构掘进参数进行对比分析,并对圆砾地层土仓压力取值范围的计算方法进行讨论。研究结果表明,圆砾地层掘进参数波动幅度较小,其中,盾构推力、刀盘扭矩、注浆压力三者存在相似的变化趋势,土仓压力则有所增长。复合地层中掘进参数中盾构推力、刀盘扭矩、注浆压力波动幅度更明显,但土仓压力基本保持稳定。采用Terzaghi松动土压力或静止土压力计算值作为圆砾地层土仓压力取值上限更为合理。三苏区间采用的掘进参数对地表沉降基本控制在5mm以内,对圆砾地层盾构施工具有借鉴意义。     

上软下硬复合地层盾构施工技术及控制策略研究

针对上软下硬地层盾构施工关键难点,依托和燕路过江通道某区间盾构隧道工程开展研究,首先介绍该区段上软下硬地层的地层分布,探究盾构施工技术的主要难点,然后通过施工中记录的掘进参数,分析掘进换刀前、后主要掘进参数的波动情况,基于推进平均速度、刀盘转矩、总推力以及管片浮动的变化情况,探究掘进过程中掘进参数控制方式,最后针对上软下硬复合地层的施工关键问题给出相应的控制策略,可为类似盾构施工工程提供建议。     

孤石发育地层盾构下穿房屋关键技术研究

镇龙南站~镇龙站左线区间出镇龙南站之后下穿多栋房屋,房屋主要为2~5层砖混结构民宅。盾构下穿房屋段隧道范围地层以花岗岩残积土及全风化花岗岩为主,存在大量孤石,在掘进过程中存在刀盘损伤、掘进参数的波动、地面建筑不均匀沉降等风险,给施工带来一系列的挑战。针对房屋对变形敏感及孤石对掘进的不良影响,对土仓压力、刀盘扭矩、螺旋机输送速度、推力等掘进参数加以控制,辅以地面袖阀管注浆加固手段,保障土压平衡盾构机在孤石地层顺利下穿房屋,节约了大量成本。     

上软下硬复合地层盾构空舱快速掘进技术

为解决上部软土下部极硬岩的复合地层盾构掘进中普遍存在的刀盘易结泥饼、刀具异常损坏和渣土超排等问题,以某城市地铁工程为依托,提出了盾构空舱快速掘进及其配套综合注浆围岩稳定控制技术,并采用数值模拟进行了理论分析。研究结果表明:提出了复合地层盾构空舱快速掘进方法,解决了复合地层段盾构推力大、易结泥饼、刀具易损坏和破岩效率低等难题,稳定了施工参数,大幅提高了施工效率,节约了施工成本。开发了空舱掘进配套的综合注浆围岩稳定控制技术,控制了地层损失,防止了隧道塌方灾害。通过建立盾构掘进动态数值模型,揭示了复合地层在空舱掘进模式下掌子面前方的围岩变形模式和地表沉降规律。     

不同地层条件泥水盾构掘进参数演化规律研究

依托南昌市轨道交通4号线(安丰站—东新站)在建泥水盾构过江隧道工程,研究泥水盾构掘进穿越不同地层时主要掘进参数的演化规律,并探讨各项盾构掘进参数之间的相关性.首先通过数理统计的方法对泥水盾构施工过程中的总推力、刀盘扭矩、掘进速度以及刀盘转速进行统计分析,着重研究掘进参数沿区间隧道纵向不同地层中的变化规律,说明盾构掘进机...     

泥岩和砂卵石交互地层盾构施工参数优化研究

在交互地层中进行盾构隧道施工是一种常见的隧道开挖工程,而盾构施工参数应与开挖地层条件相互适应。为了研究在泥岩和砂卵石交互地层中盾构施工参数的选取区与优化,文章以成都轨道交通10号线双流机场2航站楼站—双流西站盾构区间二期工程为背景,提取成都地铁盾构区间隧道下穿机场滑行面施工现场盾构机记录数据,通过数理统计方法分析了5个现场实测盾构施工参数的变化规律,结合相似工程和实际地质条件确定了各施工参数的控制范围,盾构机总推力为10～15 MN,刀盘扭矩为2.5～4.6 MN·m,掘进速度为20～50 mm/min,刀盘转速为1.0～1.5 r/min。     

软硬复合地层中盾构掘进刀盘受力分析与计算

针对广州地区典型软硬复合地层的工程地质特点,将其在盾构掘进断面内的地层简化为上软下硬的二元地层结构,基于盘形滚刀破岩受力计算Rostami公式,建立起盾构机刀盘受力的计算方法。该方法可以计算盾构机在复合地层掘进过程中的刀盘有效推力、有效扭矩、倾覆力矩和不平衡力及它们的变化情况,并以广州地铁3号线天华区间的盾构隧道掘进施工为例,对刀盘受力进行了计算,从力学角度对软硬复合地层中盾构姿态难控制、刀具易磨损等作出解释。     

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。     

Tunnelling through a frequently changing and mixed ground: A case history in Singapore

The Kranji tunnel is part of the Deep Tunnel Sewerage System in Singapore. It is approximately 12.6 km in length. Along the tunnel alignment, all the ground is composed of granite with different weathering grades (from fresh rock to residual soil). The changing ground from hard rock to mixed face and soft ground (and vice versa) at the tunnel level was anticipated. The tunnel depth along the route is between 15 m and 50 m. Two EPB TBMs were deployed at this tunnel with a bored diameter 4.90 m. These machines were designed so that both hard rock and soft ground could be excavated. The cutter head was equipped with a combination of both rippers and disc cutters. During the excavation, it was found that the frequency of the ground change between hard rock and residual soil is much higher than that expected. Due to the frequently changing ground, correspondingly the tunnel boring machine (TBM) operation mode had to be transferred frequently from hard rock tunnelling to transition mode and to earth pressure balance (EPB) close mode. It resulted in great difficulties for the TBM in an optimized operation condition. These difficulties included high cutter wear and flat cutters, tunnel face instability, water inflow at weathering interface, and time delays. In order to overcome these problems and speed up the tunnelling progress, the TBM used in the north drive was modified to attempt the frequently changing ground. The performance of the modified TBM was highly improved. However, the highly abrasive and frequently changing mixed face ground still caused high cutter wear, especially flat cutter wear. These posed many challenges to the equipment and the tunnel crew.     

Mechanical performance of TBM cutterhead in mixed rock ground conditions

The mechanical performance of TBM cutterhead including thrust, torque, eccentric force and overturning moment was calculated and analysed in different mixed rock ground conditions. The calculation model was built by identifying the rock type under each cutter using a ray intersection algorithm and calculating the cutting forces of each cutter using the CSM model. The mixed rock ground conditions were simplified as rock type distribution and rock strength classification. In the present paper, the rock distributions of the Layer-Banded Rock (LBR) and Random-Distributed Rock (RDR) types were considered. The influences of rock strength (Uniaxial Compressive Strength: UCS, Brazilian Tensile Strength: BTS), rock locations and number of rock layers were studied. For verification, a boring experiment was designed and conducted using an experimental cutterhead with 14 disc cutters. The rock box was poured with concrete C20, C40 and C60 layer by layer to prepare the LBR condition. The average torque and thrust of the calculation model and experiment were in good agreement. Some conclusions were drawn from the study on the rock strength, rock locations, area percentages of different rock layers and number of rock layers. And hence, some suggestions were proposed to enhance the tunnelling efficiency and reduce damage to the cutterhead.     

广州地区软硬复合地层盾构施工技术研究

基于广州地区典型软硬复合地层条件下的盾构掘进工程实践,分析研究了盾构掘进过程中存在的刀盘刀具磨损、姿态难控制、结泥饼和喷涌等施工风险,从盾构选型、刀具配置与管理、掘进参数控制、盾构姿态控制、渣土改良与同步注浆及信息监测与反馈等方面采取应对措施,并以广州地铁二号线越～三区间盾构隧道施工为例进行说明.     

软硬交互地层盾构长距离小半径曲线穿越地面复杂环境成套施工关键技术研究——以杭州机场轨道快线SGJC-1标为例

针对软硬交互地层盾构长距离小半径曲线穿越地面复杂环境下的施工关键技术难题,以杭州机场轨道快线SGJC-1标为依托,分析盾构在穿越多条河流、多个建(构)筑物、全断面硬岩及上软下硬地层、长距离小转弯半径以及与既有隧道道路交叠等工程重难点,并给出相应措施.     

Ground collapse caused by shield tunneling in sandy cobble stratum and its control measures

This study investigated several ground collapses in sandy cobble strata induced by shield tunneling in two intervals of Lanzhou Metro Line 1 and proposed corresponding control measures. Ground collapses were classified into three types (A, B, and C). The distribution of low-compactness zones was the primary cause of the collapses that occurred after steady excavation (A-type), indicating that advanced grouting should be conducted beneath these zones. The grouting area should be a semi-circular ring in the transverse section, with a grouting ring height and thickness of 1.05 m and 0.51 m, respectively. A poor tunneling state caused by fluidity reduction in the cutter chamber was the main reason for collapses caused by restarting the shield after long-term shutdown (B-type). We suggest rotating the cutterhead every 12 h during long-term shutdown and supplementing the bentonite until the cutterhead torque falls below 3500 kN·m. Collapses caused by cutterhead blockage (C-type) were mainly due to encountering large boulders during tunneling. We suggest pulling the front shield back with hinge equipment when the cutterhead is blocked, with a backward distance greater than the penetration distance (35 mm) and a face pressure above the limit support pressure calculated using the method presented in this paper.

     

Development and current experiences with double-shield TBMs in Italy

In the field of mechanical tunnel excavation with full-face machines, the most significant step forward is represented by the introduction of the double telescopic shield feature, which allows hard-rock machines to advance successfully in a very wide range of geological conditions with the installation of appropriate ground support systems. Since the prototype machine was designed and first applied in southern Italy in 1973–1977, several major improvements have been introduced by the author to subsequent units, with particular regard to the telescoping section connecting the main shield; the machine direction control and steering systems; and the cutterhead design, also in connection with the continuing development of full-face tunnel boring techniques and equipment.     

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.