浅谈高速铁路路基沉降量预测方法

高速铁路的路基沉降量控制,是在高速铁路设计与施工中必须要考虑的主控因素。因此在对路基进行大规模施工前,都要进行路基的沉降量观测,再结合沉降量的观测数据来进行路基沉降量的预测。路基沉降量的预测常用方式涉及到很多领域与学科综合运用,工作难度较大,长期以来,这也是高铁路基施工人员所面临的技术难题。本文对路基沉降预测中的几个典型的研究方法进行了介绍,归纳起来可以分为灰色系统法、遗传算法、曲线法和BP神经网络法。     

强夯法在重载铁路路基的应用

结合本人在重载铁路山西中南部铁路通道DK925＋720～DK927＋500段路基的强夯施工，本文主要介绍强夯法在高填方路基上的应用，采用强夯法的基本原理、实施方案、施工安排，并通过试验数据对比及沉降观测对加固效果进行了分析评价。     

沉降观测技术在高层建筑施工中的应用研究

依据高层建筑沉降规范要求,高层建筑在施工过程中、建筑物使用阶段都需对建筑进行沉降观测,本文浅要分析沉降观测技术在高层建筑施工中的应用以期能为建构筑物的正常使用寿命和建筑物的安全性提供参考。     

软土路基处理中施工监控要点及沉降观测成果评价

本文结合福建省宁德市宁武高速公路宁德段建设工程项目中监理单位在软土路基施工过程中的监控要点进行阐述,对软土路基的沉降观测进行分析和评价;宁武高速公路宁德段软土路基处理中,对软土路基进行沉降稳定观测,观测统计表明,通过对软基进行处理,严格按规范要求施工,其工程质量是能够达到预期目标的。     

路基沉降变形观测方法及数据处理

在公路的建设过程中,经常会提到有关路基沉降变形的问题,本文主要是介绍了公路建设过程中路基沉降变形观测的主要内容,沉降与稳定观测点的布设,沉降观测的要求和精度指标以及沉降观测资料的整理及沉降预测,并对所得到的数据进行相应的处理。     

高速铁路路基沉降观测的技术与要求

结合高速铁路对路基沉降的严格要求,提出了沉降测量的重要性,详述了高速铁路路基沉降观测的技术与要求,以确保施工质量和运营安全,可为今后路基沉降测量提供参考。     

浅谈高速公路路基施工质量控制

高速公路建设质量的最重要因素是路基沉降,所以要在施工过程中保证路基的施工质量必须及时掌握路基沉降的变化情况,特别是要能够较为合理地预估路基沉降的变化情况。如何确保路基工程施工质量,加快进度,提高经济效益,一直是工程建设者们探讨的问题。结合多年经验就此问题进行分析,望与大家共同探讨。     

路基施工注意问题

通过时路基产生沉降和失稳的定性分析,阐述路基产生沉降与失稳的影响因素,并针对各种影响因素加强施工过程控制,减少工后沉降和不均匀沉降的发生。     

浅谈堆载预压+沉降观测在高速铁路中的应用

在高速铁路路基基床底层施工完毕后,利用堆载作用预先将路基填筑土石方充分压缩固结,达到基本上消除设计永久荷载长期作用下所产生的沉降,使铁路路基在运营过程中基本上不产生大的沉降变形。同时,采用曲线回归法进行沉降观测数据分析,当推算出的工后沉降满足要求后予以卸载,进行下一道工序施工。     

EMD降噪在高速铁路路基沉降预测中的应用

高速铁路路基实测沉降曲线通常含有噪声,不宜直接进行曲线拟合。将EMD降噪法引入到沉降预测中,首先对路基沉降观测数据进行滤波降噪,然后将降噪后的沉降曲线作为原始数据进行曲线拟合。结合数学模拟实验和京沪高速铁路典型路基沉降板观测数据,分析了EMD降噪效果和降噪后的沉降预测结果。分析结果表明,EMD降噪很好地消除了混杂在实测沉降曲线中的随机误差和异常的波动成分;降噪后的沉降速率曲线更为平缓,能直观地反映出沉降趋于稳定的时间和过程;降噪后的曲线拟合相关系数高,误差平方和小,沉降预测精确度得到了显著提高且能够满足评估指南的要求。     

高速铁路路基沉降与列车运行速度关联性的研究

土质路基在高速列车的长期循环荷载下不可避免会发生沉降变形,列车运行速度与路基的沉降有着直接的关联性。随着列车运行速度的不断提高,对不均匀沉降变形的控制要求也越来越严格;同时,路基的不均匀沉降也制约着列车运行速度的提升,故有必要研究无砟轨道路基不均匀沉降对列车运行特性和线路冲击的影响。在既有的列车-轨道垂向耦合动力学理论模型基础上进一步考虑了轨道板下方的CA砂浆层和混凝土垫层的共同作用,建立了更符合实际线路特征的车轨耦合分析模型,并通过与现场测试结果的对比验证了该模型的合理性。基于此模型考察了不同路基沉降分布特征、不同列车运行速度条件下车辆和轨道振动特性,从车辆运行安全性和乘客舒适性两方面的指标总结了沉降的控制要求。计算发现短波长的路基沉降易于引起轮轴较大的加速度响应,线路的沉降幅值控制标准主要由安全性指标(轮轴减载率)决定;而在发生大波长的路基沉降时,主要导致车体加速度响应明显增大,路基沉降控制标准主要由列车车体舒适性指标(车体加速度)所决定,并给出具体的控制参数。     

Cause investigation of damages in existing building adjacent to foundation pit in construction

This paper presents a case study of investigating damages in existing building adjacent to foundation pit in construction, in which the settlement influence of adjacent building induced by constructing foundation pit is demonstrated by means of field observation, numerical analysis and experimental investigation. This study focuses on the principal cause inducing these damages in the existing building. This work demonstrates that the stratum settlement of the existing building during excavating foundation pit are significantly influenced by not only construction task of excavating soils but also that of dewatering soil mass in constructing foundation pit, since the principal constitution of fine sand and medium sand in the sludge can be easily run off with stratum loss during the dewatering task, and the hydraulic connection between the inside and outside of the foundation pit thus can't cut off using underground continuous wall, which can probably produce structural damage of soil mass with stratum settlement.     

Probabilistic analysis of the replacement thickness of the in-cuts roadbed in permafrost regions

Limited to terrain and road longitudinal gradient, it is inevitable to excavate permafrost for linearity engineering in permafrost regions such as railway and highway. It is a very complicated process for freezing-thawing cycle of the active layer due to parameters variability and complex climate. Moreover, there are scarce data for ground temperature and deformation in in-cuts roadbed. A probabilistic approach may consider the influences of the variation of each significant parameter upon the factor of safety and has the particular advantages over the classical approach. So it is frequently used to give a more rational assessment of the risks. A probabilistic model is put forward to evaluate the replacement thickness of in-cuts roadbed in the permafrost regions, and the procedure is validated by the observation data in cutting of Qinghai-Tibetan railway. The analysis results show that the thermal stability of the roadbed cannot be ensured if in-cuts roadbed is only displaced by coarse-grained soils. The reliability can be improved greatly if the thermal-insulated material is embedded in the replacement layer. The calculation results show that the maximum thawed depth of in-cuts roadbed will not be deeper than the replacement layer if the Extruded Polystyrenes (EPS) with a thickness of 10.0 cm is embedded at the depth of 0.8 m below the surface of the imported fill layer. The computation results also indicate that the in-cuts roadbed design in the Qinghai-Tibetan railway can protect the permafrost under the replacement layer from thawing and ensure the in-cuts roadbed stability in the coming fifty year. The Monte Carlo simulation and the first-order second moment method are applied to establish the limit-state function of probabilistic analysis of the replacement thickness. The calculated results indicate that probabilistic approach can be used to determine the replacement thickness and can provide more reasonable suggestions for engineering application than the classical approach.     

基于车辆响应的无砟轨道路基不均匀沉降评价指标理论研究

路基不均匀沉降的合理评价对于保障高速铁路运营安全和指导线路养护维修至关重要。传统路基沉降评价多基于沉降幅值单一指标,缺乏对车辆运营速度、路基沉降波长的综合考虑。该文基于建立的精细化多车-无砟轨道-路基耦合动力学模型,分析了路基不均匀沉降下的车辆动力学响应特征以及运营速度、沉降波长及幅值对车辆响应的影响规律,在此基础上提出了沉降时变率指标用于路基不均匀沉降评价。结果表明:沉降时变率能融合车辆运营速度、沉降波长、波幅三者对高速列车动力学响应的共同影响。沉降二阶时变率和轮轨垂向力、轮重减载率安全性指标呈显著的线性映射关系;沉降一阶时变率和车体加速度等舒适性指标呈较为显著的线性映射关系;并提出了轮重减载率、车体加速度与沉降时变率的拟合公式。研究成果可为高铁线路设计和养护维修提供参考。     

Characteristics of roadbed settlement in embankment-bridge transition section along the Qinghai-Tibet Railway in permafrost regions

The Qinghai-Tibet Railway (QTR) project was finished on July 1, 2006, and has served for over 3 years. Judging from the present situation, the roadbed is stable and train speed in permafrost regions achieves 100 km/h as expected during the designing. However, as half part of the roadbed was constructed over the permafrost characterized by high ground temperature and high ice content, slight changes of the permafrost might lead to roadbed problems, of which the settlement in embankment-bridge transition section is an obvious and special one. Investigated results of 164 bridges and accounting to 656 positions from the Xidatan Basin to the Chiqu Valley along the QTR in 2009 showed that the settlement was influenced by factors including bridge orientation, embankment slope direction, embankment height, ground temperature, ground ice content of permafrost and local subgrade soil type. For the average value of the settlement, it was greater at the northern end of a bridge than that at the southern end, and was greater in sunny-slope than that in shady-slope. It was greater in high ice permafrost regions than that in low ice regions, and was greater in high-temperature permafrost regions than that in low-temperature regions. Additionally, it increased logarithmically with the height of the embankment. In regions where the subgrade soils were dominated by silt, silty clay or fine sand, the settlement amount was higher than that in bedrock regions. Correlation analysis results showed that there were good relationships between the settlement and the slope direction, embankment height, ground temperature and ice contents when some of the later items were quantified. The correlation coefficients were 0.234, 0.213, −0.21 and 0.151 respectively, when the factors were quantified.     

浅谈莱钢22000m~3/h制氧机工程建设

简介莱钢 2 2 0 0 0m3 /h制氧机工艺特点及设备配置 ,就工程建设做法与施工中的问题及处理情况进行了详细介绍 ;莱钢 2 2 0 0 0m3 /h制氧机从破土动工到出氧总共用了 2 2 4天     

胶州湾海底隧道不对称双连拱断面施工优化分析

以青岛胶州湾海底隧道中的不对称双连拱隧道为工程背景,选取主隧道与匝道交叉口段的典型断面建立数值计算模型,针对不同的施工开挖顺序和掘进进尺制订了4种施工方案,并采用有限差分软件FLAC3D进行动态施工的三维数值模拟,计算分析并比较各方案的地表沉降、拱顶沉降和支护结构位移以及围岩应力和支护结构应力的分布情况,明确不对称双连拱隧道施工中结构变形及应力的最不利位置。分析结果表明,先施工中导洞再施工匝道断面右导洞并采用小进尺的施工方案更有利于控制围岩的稳定性,并据此提出了合理的施工方案建议。     

京沪高速铁路北京至沧州段桥梁工程施工与创新

针对京沪高速铁路北京至沧州段桥梁工程特点,重点介绍了代表性特殊结构桥梁的施工方法、区域性地面沉降地区桥梁工后沉降的控制措施,以及保证350 km/h无砟轨道高平顺性的施工技术创新措施。     

地铁施工安全仪表盘技术研究与应用

地铁施工安全受工程地质条件、当前施工进度、周边环境等多因素综合影响。通过构建可视化仪表盘,基于地铁工程三维实体模型,动态显示在上述各影响因素耦合作用下工程的安全状态,支持作业风险和危险构件及其影响区域实时预警和控制,准确识别工程的最危险部位、风险区域分布、等级状态等,为现场安全管理提供决策支持。     

地面沉降对路基上双块式无砟轨道平顺性的影响

高速铁路无砟轨道对于基础沉降变形特别敏感,地面沉降会显著影响路基上无砟轨道的受力变形及使用寿命,影响高速列车安全平稳运行。该文针对路基上双块式无砟轨道,基于有限元方法建立了梁-板-实体空间耦合模型,对地面不均匀沉降的幅值、范围及型式与双块式无砟轨道系统平顺性的关系开展了研究。结果表明:无砟轨道及路基各层沉降量随着地面沉降量增加基本成线性增加,支承层和路基表层间沉降差较大易出现离缝问题;地面沉降量20mm、沉降范围小于15m时,路基及轨道结构离缝现象明显,沉降范围大于15m时结构变形趋于平缓、轨面曲率半径增大;地面错台和折角型不均匀沉降均易导致无砟轨道及路基在折角点出现沉降差、结构离缝甚至开裂,折角值大小直接影响轨面平顺性。