基坑多步开挖和支护的有限元增量分析方法

本文从具有初始应力的变形体的虎功原理出发,阐述了基坑多步开挖和支撑的有限元增量分析方法,并将根据该方法编制的弹塑性有限元程序用于实际工程的位移反分析及预测,获得了令人满意的结果。     

紧贴已建轨交车站的超深基坑开挖卸载效应数值模拟分析

结合上海某轨交建设工程实例,采用地层位移法,运用叠加原理和增量法,对紧贴既有轨交车站（地下连续墙共用）的深基坑开挖过程进行了二维和三维数值模拟。着重分析了深基坑开挖卸载作用下,既有车站结构的内力变化和变形趋势,对深基坑工程的施工提出了合理的控制要求。     

隧道设计计算模型对围岩适应性的探讨

文章归纳总结了目前隧道衬砌结构计算的几种常见模型,通过对在相同条件下的隧道采用不同模型的计算结果进行分析,指出了各种模型间的主要区别,同时探讨了各种模型对不同地层的适应性,提出了不同的围岩对应不同计算模型的原则和建议.     

基于荷载试验的刚架拱桥修正模型计算评估法

文章针对刚架拱桥的承载能力评估问题进行研究,提出刚架拱桥承载能力评估方法——动静载试验评估法,利用随机振动的动力测试的数据,通过基于敏感性设计参数模型修正法对刚架拱桥有限元模型进行修正,并结合动静载试验实测数据与修正后的模型理论计算值进行对比分析,使有限元模型更好地反映逼近损伤后的刚架拱桥整体结构受力特性,从而对钢筋混凝土刚架拱桥承载能力进行评估。     

共用地下连续墙同期施工中地铁基坑工程的设计实践

结合上海轨道交通13号线世博园区专用交通联络线卢浦大桥站的工程实践，介绍共用地下连续墙的两个相邻基坑工程在同期分阶段施工时的围护结构设计、理论分析和实测结果，对共用围护墙设计提出若干建议。     

武汉市供水管网水力计算模型的建立

从武汉市供水管网实际出发，介绍了建立管网水力工况分析中基础资料的收集处理及计算模型的校核，模型建立方法及使用效果，并对模型的局限性进提出了改进设想。     

基坑开挖对地铁区间隧道影响的计算分析

结合工程实例,运用土体、围护结构相互作用有限元计算原理,对基坑开挖时由于土体应力释放和降承压水作用对地铁区间隧道的影响进行了计算分析,并提出降低其影响的建议及措施,可供类似工程参考。     

石南油田多相流管线工艺计算模型的选择

运用不同的模型对石南油田的一条多相流管线的压降进行了计算,与实测值相比,计算结果均不理想。因此针对该多相流管线提出了一种新的组合模型,经计算比较,该模型对石南多相流管线有足够的精度,能满足工程上的要求。     

连续墙支挡结构的深基坑开挖过程有限元分析

各类深基坑的破坏大都是在基坑开挖过程中出现的支护结构的破坏,已经成为引起基坑失稳的主要原因。本文以某地铁车站深基坑为研究对象,利用PLSXIS有限元分析软件,对基坑开挖和支护的过程进行模拟分析,探讨了基坑开挖深度、支护结构位移、土体位移等问题,提出控制基坑失稳的方法和建议,为类似的深基坑工程的施工提供参考。     

SMW工法在南京地铁围护工程中的应用

SMW围护施工工法国外应用较多,目前在国内处于推广阶段.文章介绍了在南京地铁珠江路车站围护工程施工中SMW工法的应用情况,用工程实例说明了此工法在大型、超深基坑围护工程中应用的可行性.     

上海地铁中兴路车站围护结构设计

时空效应计算理论是近年来我国深基坑计算的新理论;抗隆起计算是决定性地下连续墙人土比的决定性因素.文章主要介绍了上海地铁中兴路车站围护结构的设计和抗隆起计算,重点阐述了在围护结构设计中如何应用时空效应理论.     

半荷载结构法检算浅埋(偏压)隧道结构之探讨

浅埋和偏压隧道在隧道规范和设计手册中都列有荷载计算公式.对于整体式衬砌,多年来均用荷载结构法进行结构检算,计算中不考虑施工支护受力,当前的标准图均按此法编制.近年来,锚喷支护的使用日益普及,尤其在浅埋和偏压地段锚喷的厚度大、强度高,投入费用大,其作用已不可忽视.文章提出的半荷载结构法,采用规范规定的荷载,可考虑锚杆加固后的围岩以及锚喷初期支护受力,与以往的荷载结构法相比较,认为采用半荷载结构法更加稳妥和合理.     

Bus arrival time calculation model based on smart card data

Bus arrival time is usually estimated using the boarding time of the first passenger at each station. However, boarding time data are not recorded in certain double-ticket smart card systems. As many passengers usually swipe the card much before their alighting, the first or the average alighting time cannot represent the actual bus arrival time, either. This lack of data creates difficulties in correcting bus arrival times. This paper focused on developing a model to calculate bus arrival time that combined the alighting swiping time from smart card data with the actual bus arrival time by the manual survey data. The model was built on the basis of the frequency distribution and the regression analysis. The swiping time distribution, the occupancy and the seating capacity were considered as the key factors in creating a method to calculate bus arrival times. With 1011 groups of smart card data and 360 corresponding records from a manual survey of bus arrival times, the research data were divided into two parts stochastically, a training set and a test set. The training set was used for the parameter determination, and the test set was used to verify the model’s precision. Furthermore, the regularity of the time differences between the bus arrival times and the card swiping times was analyzed using the “trend line” of the last swiping time distribution. Results from the test set achieved mean and standard error rate deviations of 0.6% and 3.8%, respectively. The proposed model established in this study can improve bus arrival time calculations and potentially support state prediction and service level evaluations for bus operations.     

A model for the structure of lane-changing decisions

A structure is proposed to connect the decisions which a driver has to make before changing lanes. The model is intended to cover the urban driving situation, where traffic signals, obstructions and heavy vehicles all exert an influence. The structure is designed to ensure that the vehicles in traffic simulations behave logically when confronted with situations commonly encountered in real traffic. The specific mathematical expression of the questions embedded in the decision process and employed in the present implementation of the model are not critical and can be replaced by alternatives, but the heirarchy of the decisions is crucial. On the basis of experience to date, the lane changing model produces a realistic simulation of driver behaviour and has proved very robust under a wide range of conditions.     

三门海特大桥深水基础施工技术研究

三门海特大桥复杂的天然条件相对于主墩的深水基础施工而言相当恶劣,通过对高桩承台三个方案的优化比选,确定了承台采用钢吊箱施工方案,并详细介绍了水中临设、深水桩基、钢吊箱施工的方法,最后对深水基础施工进行了系统总结。     

盾构出洞冻结加固拱棚结构的力学模型分析

将盾构出洞冻结法加固拱棚结构简化为单心固定无铰拱和直墙拱两种计算模型,利用实例工程对结构进行内力计算和验算,比较安全系数,并与实例工程实测压力结果对比,表明直墙拱模型是较为接近实际冻结壁结构的一种可行简化计算模型,为类似工程设计提供参考.     

地铁盾构隧道施工对近接桩基的影响研究

采用三维有限元方法对盾构隧道近接桩基施工进行模拟,分析盾构机动态掘进时既有桩基位移的变化规律.模型中实现了盾构施工过程的步步掘进模拟,采用了接触单元来模拟桩基与土体的相互作用,并考虑了注浆层硬化的时间过程.计算结果表明,盾构隧道修建时,既有桩基将产生沉降和倾斜,桩基与土体的沉降差导致它们的接触面在地表处产生滑移,桩基顶部向隧道侧挤压,而在另一侧与土体脱离.施工参数的敏感性分析表明,增大顶进力会增大施工期间的桩基倾斜率,但对最终倾斜率影响不大;增大注浆压力则将增大桩基的最终倾斜率.该工作可为类似工程的施工提供参考.     

A flexible model structure approach for discrete choice models

Multi-dimensional discrete choice problems are usually estimated by assuming a single-choice hierarchical order for the entire study population or for pre-defined segments representing the behavior of an “average” person and by indicating either limited differences or a variety in choices among the study population. This study develops an integral methodological framework, termed the flexible model structure (FMS), which enhances the application of the discrete choice model by developing an optimization algorithm that segment given data and searches for the best model structure for each segment simultaneously. The approach is demonstrated here through three models that conceptualize the multi-dimensional discrete choice problem. The first two are Nested Logit models with a two-choice dimension of destination and mode; they represent the estimation of a fixed-structure model using pre-segmented data as is mostly common in multi-dimensional discrete choice model implementation. The third model, the FMS, includes a fuzzy segmentation method with weighted variables, as well as a combination of more than one model structure estimated simultaneously. The FMS model significantly improves estimation results, using fewer variables than do segmented NL models, thus supporting the hypothesis that different model structures may best describe the behavior of different groups of people in multi-dimensional choice models. The implementation of FMS involves presenting the travel behavior of an individual as a mix of travel behaviors represented by a number of segments. The choice model for each segment comprises a combination of different choice model structures. The FMS model thus breaks the consensus that an individual belongs to only one segment and that a segment can take only one structure.     

复式拱桥加固与保护设计

以古拱桥与现代新拱桥迭合而成的复式拱桥的加固与保护设计为例,通过现场病害调查、合理计算模型的探讨找出病害所在及病害产生的原因,提出了桥梁加固与保护所采取的方法。