盾构竖向姿态预测模型参数的全局敏感性分析

盾构姿态偏离设计轴线是施工中常见的问题,因此确定影响盾构姿态的敏感性因素对于盾构姿态控制具有重要意义.为定量分析影响盾构竖向姿态的敏感性因素,以成都卵石下伏膨胀泥岩地层盾构施工为工程背景,将主要掘进参数、地质参数和几何参数作为输入变量,盾构竖向趋向作为输出变量,采用支持向量回归(SVR)算法建立盾构竖向姿态预测模型;在...     

软土地层加固对盾构姿态调控及地层变形的影响研究

Based on the large-diameter shield tunnel project in soft soil strata in Hengqin District of Zhuhai City, this paper establishes a numerical simulation and analysis model for large-diameter shield tunnelling in unrein-forced and pre-reinforced strata, and investigates the relationship between the deflection moment and pitch angle of the shield machine as well as the impact of the changes in the machine′s attitude on the deformation of the strata by changing the load distribution of the thrust system to apply the deflection moment. The results show that the gravitational eccentric moment that causes the initial bow of the shield machine is 261 MN·m, and the deflection moment required to level the attitude under the condition of pre-reinforced strata is about 21 MN·m, which is 81.1% smaller than the condition of un-reinforced strata (111 MN·m). Under the condition of pre-reinforced strata, for every 100 MN·m increase in the positive deflection moment, the pitch angle of the shield machine will increase by about 0.015°, which is 84.2% smaller than the condition of un-reinforcement (0.095°). Also, under the condition of identical negative deflection moment, the absolute value of pitch angle after pre-reinforcement is more than 85.0% smaller than the un-reinforced case. Pre-reinforcement of the strata results in a reduction of over 95.0% in both the maximum uplift and maximum settlement of the ground surface. © 2023 Editorial By Modern Tunnelling Technology. All rights reserved.     

接力吊装盾构机入井的强度校核与应用

红花套镇-云池江底隧道是忠武(忠县-武汉)输气管道实现长江穿越的重点工程。为了保证引进的德国海瑞克公司的AVN2440Ds泥水平衡式盾构掘进机(简称盾构机)在隧道内正常施工,将其吊装入井是关键。针对实际吊装中,吊车钢丝绳有效长度短这一难题,对吊车及工器具进行了强度校核分析,研制了接力吊装方案,实践应用效果较好。     

国产化盾构掘进自动导向系统的研制

介绍了盾构掘进自动导向系统的发展过程,提出研制国产化盾构掘进自动导向系统的依据,分析了系统的基本组成、基本原理、软件计算法和可靠性设计特点,通过推广应用,证明该系统具有高可靠性和高稳定性,达到国际同类产品的技术性能。     

圆锥螺纹测量成像方法

对圆锥螺纹的透射成像方法进行了实验研究和理论分析。透射成像法是将螺纹放在平行光场中以得到清晰的螺纹牙形图像，并用CCD摄像机采集到计算机内部，可用于进一步的尺寸测量。在透射成像时，螺旋线对投影螺纹牙会造成一定的遮挡。可以通过旋转螺纹轴线，使螺旋线的切线与光轴平行的方法消除，但是引入了螺纹牙的投影误差。经过分析，由此产生的投影误差可以忽略。     

公路工程测量中的常见问题及对策研究

公路工程事关人们的出行质量,施工单位组织施工期间应对所有潜在的质量、安全等隐患予以监测,并提出应对措施。从公路工程测量的角度出发,分析测量期间重视程度、专业人员、设备及具体操作等常见问题,并按照公路工程测量标准和规定,提出测量方法的优化措施,旨在提高公路工程测量质量,取得良好的测量效果。     

盾构隧道纵向刚度计算方法以及影响因素研究

伴随着国内外隧道的大量修建,盾构隧道的纵向不均匀沉降或过量沉降问题日益突出。在盾构隧道的纵向结构设计中,纵向刚度的确定至关重要,尤其对于大直径断面,以在建的南京过江隧道为例,因螺栓导致的管片横向、纵向刚度差异达数十倍。文章采用志波由纪夫纵向刚度计算公式和有限元建模的方式,对比两种方法的差异,并讨论纵向等效刚度折减系数在各种影响因素(管片尺寸、螺栓预紧力、偏心距)变化时的规律,提出采用有限元模拟管片更能贴近实际工程的受力状态,在分析复杂受力状态时可为设计提供理论依据。     

基于SegFormer模型的盾构隧道管片间缝高精度测量

为高效准确地测量盾构隧道管片拼装缝隙,构建基于SegFormer模型的管片间缝分割算法,提取管片间缝的灰度空间分布信息,实现对图像特征从粗到精的编码,在捕捉局部精细特征的同时保留管片间缝的全局分布信息,从而提高算法的鲁棒性和准确性。研究表明,基于SegFormer的管片间缝分割算法测量精度在2～3个像素以内。为了便于管片间缝测量算法的应用推广,提出智能手机结合激光测距和双侧补光的方案,将算法部署到云服务器上,通过APP调用的方式实现现场管片间缝的快速测量。与人工测量结果的对比验证表明,利用具有10倍光学变焦性能的手机拍摄5 m以内的管片间缝,物理精度在0.5 mm以内,满足管片间缝测量规范的要求。     

泡沫剂对土压平衡盾构主要掘进参数的影响研究

为实现土压平衡盾构快速高效掘进,文章依托厦门地铁2号线3标湿地公园站—五缘湾站区间盾构施工,进行盾构主要掘进参数的影响因素研究,分析了泡沫剂参数与盾构掘进参数的内在关系.通过4种泡沫剂的室内配比试验,并结合现场试验,研究泡沫剂浓度、气液比和泡沫注入比对改良土体的内摩擦角和容重的影响.结果表明,泡沫剂浓度增大1％,渣土内...     

复合式盾构应用技术分析

文章简要介绍了复合式盾构的概况和特点,并结合一些工程实例着重叙述了复合式盾构在地铁施工中的应用和出现的问题以及对策,提出了复合式盾构的发展前景,指出了改进的建议.     

土压平衡盾构故障诊断及保养系统的研制与开发

文章以目前地铁建设中常用的土压平衡盾构为背景,介绍了盾构故障诊断及保养系统的总体结构方案、知识库知识的获取建立、推理机的设计及系统的主要工作流程等,旨在通过系统的研制与开发,提高盾构掘进机的施工效率.     

复合地层中盾构滚刀磨损原因分析及对策

通过系统地总结和分析约40台次混合式盾构机在复合地层中掘进近100 km的滚刀磨损情况,对滚刀磨损做了定性分类,并根据滚刀磨损的影响因素,提出滚刀磨损的对策,以期指导今后复合地层施工中盾构机刀盘刀具选择、配置及盾构掘进。     

数字图像处理技术在隧道围岩收敛量测中应用的初步研究

文章系统地总结了国内外图像处理技术在隧道工程中的应用现状和隧道变形收敛量测的各种方法,并对各种方法的优缺点进行了详细分析;尝试了应用数字图像处理技术对隧道围岩收敛进行量测的新方法(二次比较法);编制了一套隧道图像处理系统(TUNNEL IMAGE PROCESSING SYSTEM,简称TIPS)。室内试验证明,本系统对距离的量测结果是可靠的,灵敏度和精度达到了相关要求。本研究成果可供有关人员在现场实用研究中参考。     

Some experience with a multiple linear regression method of estimating parameters of the traffic signal departure process

Before any method of data collection becomes accepted as a practical tool, it should first be widely tested. This paper analyses in detail a regression method of estimating saturation flow, effective green time and pcu values on traffic signal approaches which has previously been suggested by one of the authors. The method is applied by dividing the green time given to an approach into consecutive “first”, “middle” and “last” counting periods, covering the build up to saturation flow at the start of green, the period of constant saturation flow and the fall-off of saturation flow during the amber period. To estimate parameters, the number of straight-on cars in each counting period is regressed against its length and the number of vehicles of other types departing. It is shown that the method as previously described should be modified in two ways; first, counts from amber periods should not be included in the regression when pcu values are being estimated, and second, a weighted rather than unweighted regression should be used to ensure constant variance of the error term. An optimal sampling policy which produces parameter estimates with minimum variance is described. Applications of the method to data from several sites are described. It is shown that standard errors of parameter estimates are simply related to measurable variables. This allows simple formulae for the minimum number of observations required to achieve specified accuracies to be determined. Formulae for minimum sample sizes required to detect specified differences in saturation flow are also derived. In particular, it is shown that it is most economical, in term of sample size, to use data from single lane sites when testing differences in saturation flow between different times of day. When data from more than one site are available for testing differences, a composite test can be used which reduces sample sizes at individual sites over those required when testing a single difference.     

Integrated expression method for technical mapping of traffic parameters using RGB color model

In the field of traffic flow, speed, density, time, and distance are fundamental variables analyzed to predict traffic conditions. Reliable sources of information are gauged using tested mathematical approaches that have been developed. However, a fundamental diagram that could serve as a basis for expression techniques has not been devised. Red–green–blue (RGB) color modeling was used to overcome this limitation in traffic flow. The purpose of this study is to provide a way to understand traffic flow conditions based on features of three traffic flow elements simultaneously. The limitation of three‐dimensional expressions in two‐dimensional paper was extended to multi‐dimensional information. Information on speed, density, and flow were combined into a single RGB color and given the name RGB flow‐density space time‐distance space. This cancels out the effect of each individual's vehicular trajectories and contains five major components of a specific road section. The new gizmo aims to provide information on traffic flow conditions in transition and to stimulate further approaches related to the predictions and understanding of traffic flow. Copyright © 2016 John Wiley & Sons, Ltd.     

试用TV成像技术研究长大隧道围岩地质参数

文章介绍了TV成像技术的定义和技术原理,阐述了应用该技术研究特长隧道围岩地质参数的特点和难点以及取得的研究成果,对今后该项技术的进一步推广和应用有促进作用.     

Discrete and continuous models for computation of optimal vertical highway alignment

This paper describes a dynamic programming model and a state parametrization model formulated to solve two-dimensional highway location problems. A numerical example is presented to compare the solutions obtained using the two models. Features of the two approaches, with respect to their applicability in solving three-dimensional highway location problems in particular, are highlighted. This study forms the basis of a three-dimensional model that computes optimal horizontal and vertical alignments simultaneously.     

Identification of occupant posture using a Bayesian classification methodology to reduce the risk of injury in a collision

Recent studies have shown that smart restraint systems, which will recognize and then adapt to a specific collision and occupant combination, have a strong opportunity to significantly reduce occupant injuries during a traffic accident. As a step toward the development of these adaptive restraint systems, this study proposes a novel methodology for the classification of pre-crash occupant posture. Various occupant postures were simulated with a human model and the corresponding data was recorded using sensor models implemented in a mid-size car interior. The sensor data was then used to train two Bayesian classifiers which categorized an unknown occupant posture as one of nine predefined classes. The posture classifiers and a look-up table which contained optimized restraint laws for each class were combined to form catalog controllers for the restraint systems. The benefit of these restraint systems with catalog controllers vs. a restraint system optimized at a nominal posture was estimated by analyzing crash simulations with the occupant in 200 different postures. While the minimum error rate classifier showed the highest correct classification rate (90%), the Bayesian minimum risk classifier estimated the highest average injury reduction (21%). As expected, the highest injury reduction (up to 45%) was recorded for the posture classes closest to the windshield, whereas the lowest injury reduction was found for the classes closest to the nominal position. While the proposed restraint system with a catalog controller requires considerable “offline” computational effort, it is more versatile in terms of using complex human models and injury criteria and is much faster during the brief decision window available than recent “online” controllers proposed previously in literature.     

The existence, uniqueness and computation of an arc-based dynamic network user equilibrium formulation

In this paper, a dynamic user equilibrium traffic assignment model with simultaneous departure time/route choices and elastic demands is formulated as an arc-based nonlinear complementarity problem on congested traffic networks. The four objectives of this paper are (1) to develop an arc-based formulation which obviates the use of path-specific variables, (2) to establish existence of a dynamic user equilibrium solution to the model using Brouwer's fixed-point theorem, (3) to show that the vectors of total arc inflows and associated minimum unit travel costs are unique by imposing strict monotonicity conditions on the arc travel cost and demand functions along with a smoothness condition on the equilibria, and (4) to develop a heuristic algorithm that requires neither a path enumeration nor a storage of path-specific flow and cost information. Computational results are presented for a simple test network with 4 arcs, 3 nodes, and 2 origin–destination pairs over the time interval of 120 periods.