无砟轨道基桩控制网测量技术探讨

轨道的高平顺性是客运专线无砟轨道最突出的特点之一。因此,需要建立高精度的铺轨基桩控制网。基桩控制网通常是按五等导线测量的方法进行布设,本文提出在导线基础上采用边角后方交会法来加密,通过运用原始数据误差理论和仿真实验的方法对无砟轨道控制基桩网的新旧两种测量技术进行对比,结果显示:采用边角后方交会法加密的控制网将得到更高的相对点位精度,具有更好的平顺性指标。这一结论对我国客运专线无砟轨道施工控制网的建设或许有参考价值。     

Response evaluation for horizontally loaded fixed‐head pile groups using 3‐D non‐linear analysis

The response of laterally loaded pile foundations may be significantly important in the design of structures for such loads. A static horizontal pile load test is able to provide a load–deflection curve for a single free‐head pile, which significantly differs from that of a free‐ or fixed‐head pile group, depending on the particular group configuration. The aim of this paper is to evaluate the influence of the interaction between the piles of a group fixed in a rigid pile cap on both the lateral load capacity and the stiffness of the group. For this purpose, a parametric three‐dimensional non‐linear numerical analysis was carried out for different arrangements of pile groups. The response of the pile groups is compared to that of the single pile. The influence of the number of piles, the spacing and the deflection level to the group response is discussed. Furthermore, the contribution of the piles constituting the group to the total group resistance is examined. Finally, a relationship is proposed allowing a reasonable prediction of the response of fixed‐head pile groups at least for similar soil profile conditions. Copyright © 2005 John Wiley & Sons, Ltd.     

Seismic Response Analysis of Portal Water Injection Sheet Pile

1 Introduction The portal water injection sheet pile (PWISP) is a new type of space-retaining structure developed for the Shengli Oil Company. It was developed based on the combination of the practical needs of hydraulic projects and the technical principle of jet-drilling in the oil indus-try and has been successfully used for disaster prevention and hydraulic projects (Guo, 2002, 2005). It consists of the double-row parallel-prefabricated reinforced concrete sheet piles and the connectio…     

Numerical modelling of the driving response of thin‐walled open‐ended piles

The driving response of thin‐walled open‐ended piles is studied using numerical simulation of the wave propagation inside the soil plug and the pile. An elastic finite element analysis is carried out to identify the stress wave propagation in the vicinity of the pile toe. It is found that the shear stress wave has the highest magnitude above the bottom of the soil plug. Below the bottom of the soil plug, the vertical stress wave has the highest magnitude. Although the shear stress wave propagating in the radial direction is similar in magnitude to the vertical stress wave at the bottom of the soil plug, it decays rapidly while travelling downwards. The highest vertical stress at the bottom of the soil plug appears after the vertical stress wave interacts with the shear stress wave travelling in the radial direction. Initially, the vertical stress wave propagates with the dilation wave velocity in both the radial and vertical directions. After it interacts with the shear stress wave, the vertical stress wave starts to propagate with the shear wave velocity in the radial direction and with the axial wave velocity downwards. It is concluded that at the bottom of the soil plug, the interaction between the waves travelling in radial and vertical directions is important. The capabilities of several one‐dimensional pile‐in‐pile models to reproduce the driving response given by a two‐dimensional axisymmetric finite element model is studied. It is seen that when the base of the soil plug fails, a one‐dimensional pile‐in‐pile model can be used to achieve results in agreement with the finite element model. However, when the pile is unplugged, where the base of the soil plug does not fail, a reduced finite element mesh that permits the radial wave propagation inside the soil plug must be used. Copyright © 2001 John Wiley & Sons, Ltd.     

对101层上海环球金融中心桩筏基础性状的预测

根据上海金茂大厦88层的成功建筑经验,试图预测101层上海环球金融中心桩筏基础性状,例如桩的承载力和及其随时间的增加、桩筏的荷载分担、筏厚、沉降和桩筏基础的设计理论等。最后,对两幢大楼桩筏基础性状加以评论,可供研究上海超高层建筑的超长桩基的设计理论的参考。     

岩溶地区冲孔灌注桩的施工方法

以龙岩地区岩溶地带某一项目施工为例，分析冲孔灌注桩孔内漏浆、塌孔的原因，探讨在岩溶地区预防和处理塌孔的方法：改善泥浆品质，安放钢护筒，挤压黄土入裂隙，减小泥浆渗透，以及分层加入一定量水泥，使其形成水泥土护壁层。实践证明，诸类方法的使用可有效遏制孔内漏浆和塌孔，提高施工效率。     

液化地层震动沉管桩施工对策

南京某综合办公楼桩基工程采用震动沉管桩，由于该区地层的粉砂层存在不同端阻力分界面，因上层长时间的震动，下层粉砂层发生液化，导致桩尖与沉管脱离，桩管内出现水泥浆：为此在施工中采用活瓣桩尖，并用0．5m^3的砼封底，有效地解决了桩管冒浆问题。     

长螺旋混凝土压灌桩在地基处理中的应用

茂名石化100万t/a乙烯改扩建工程场地位于破碎带上，场区地质条件复杂。在厂区地基处理中，采用长螺旋混凝土压灌施工方法。施工过程中严格对正桩孔，控制转速，按比例合理配制混凝土，并针对该类型桩施工中常见的7种质量缺陷提出了相应解决方案和控制措施。     

预防水下灌注混凝土质量事故的对策

通过工程对比试验和施工实例，描述了桩基工程水下灌注混凝土的运动过程，指出了从业人员在施工中存在的认知误区，对漏筋（缩径）、浮笼、断桩等常见桩基事故发生的原因进行分析，提出了有别于施工规范和相关施工手册上解释的新观点，在施工实践中总结出了避免水下灌注混凝土常见质量事故的新办法——拔管后导管埋深以1m为度控制法，并将这种方法归纳总结为“跑步”理论。     

桩基工程施工安全技术措施的实施

桩基工程的投标文件及施工组织设计均要编制安全技术措施，根据钻探施工中有关安全规程，对每一个工程项目，都要建全安全生产责任制，加强上岗人员安全教育，保证在每一道工序开工前，都有详细的施工安全方案和保障措施，并在施工中全面落实，另外施工过程中对安全内容要按规定实行逐级交底。