超软土真空预压室内模型试验研究

随着围海造陆的发展,吹填区底面标高越来越低,吹填土厚度由原来的2 m达到现在的10 m左右,使地基加固时发生很大的压缩变形。在现场真空预压检测过程中发现土体加固后形成上面一层2～3 m的硬壳层,地表以下3～4 m土层强度增长很小。通过超软土真空预压室内模型试验发现加固后由于超软土发生很大的压缩变形,使排水板发生了很大的扭曲变形,甚至发生局部折断现象,导致排水板失效或效率降低,从而使土体加固效果欠佳。在加固土体变形基本稳定后,进行了二次插板再加固的试验,结果表明,土体的沉降进一步发展,含水率进一步降低,十字板强度进一步提高,且沿深度递减幅度大为减小,证明了第一次加固过程中由于土体发生大变形使排水板效率降低,地基不能达到预期的加固效果;采用二次插板可使吹填土产生较好的加固效果。研究成果为探索更有效地加固深厚吹填土方法提供了依据。     

关于建设数字郑东新区的构想

郑东新区是一个新规划的城区,在城市建设的同时进行信息化建设将比其它城市具有更大的优势和发展机遇。文章探讨了数字郑东新区的总体框架、空间基础设施、标准体系建设,以及在信息化建设中的重点电子工程。并提出了加强组织体系建设、制订信息化战略、加强信息安全保障、完善融资体系等保障措施。     

“十五”地磁相对记录仪器干扰分析与安装方案改进

描述了地磁相对记录仪器FHDZ-M15地磁总场与分量组合观测系统和GM4磁通门磁力仪,在安装中需要注意的问题,和记录曲线上表现出来的干扰形式。通过分析干扰产生的原因,最后给出记录仪器的改进安装方案。     

市级气象通信网的建设安装与维护

随着接入技术和网络技术的发展,必须建设气象宽带通信网,提升气象部门网络间的信息通信能力,以满足日益增长的气象业务发展需求。该文通过通信线路选择、网络协议选择、网络拓扑结构设计,以及网络接入设备连接等几个方面,介绍了市级气象宽带通信网的建设、安装情况,同时对通信网运行过程中的常见故障进行了分析和诊断,并结合实践总结出快速准确地排查网络故障的“从内到外,由近及远,先软后硬,分段检测”原则。     

油气井永久性光纤Bragg光栅传感监测系统安装设计

油气井永久性光纤Bragg光栅传感监测系统的安装设计是现场应用的一个重要组成部分,也是工艺最复杂、成本最昂贵的一个环节.本文简要地回顾了油气井光纤Bragg光栅传感监测系统安装现状,根据国内常用射孔完井方式,设计了两种单井光纤Bragg光栅井下安装模型.论述了井下安装前准备工作和主要注意事项,讨论了存在问题,对油气井永久性光纤Bragg光栅传感监测技术及其安装技术的前景进行了展望.     

ADS100数字航摄系统的安装与调试

ADS100数字航空摄影测量系统是目前最新一代的数字航空摄影测量系统,具有航摄效率高、数据信息量丰富、系统性能稳定、内部集成高精度IMU系统等一系列优势。该系统设计精密、构造复杂,其安装和调试是确保航摄顺利进行的前提条件和基本保障。本文结合大量的航摄生产经验,总结出ADS100航摄系统安装和调试的方法和注意事项,具有较强的参考价值。     

几种雨量观测方式比对试验分析

为进一步了解不同雨量观测方式对降水测量的影响,在中国气象局大气探测试验基地进行了几种雨量观测方式的比对试验。本文利用该试验的观测资料,分析了不同雨量计及其不同安装方式对降水测量的影响,并分别给出了各雨量计的测量值。结果表明:降水测量与雨量计的安装方式极其相关,坑式安装测量的雨量值最大,其余依次为双栅、防风圈和平地安装(呈水口高出地面70cm);当前业务观测方式测得的降雨量偏小;降雪测量受风场的影响比液态降水测量更显著。     

Numerical investigation of pile installation effects in sand using material point method

The installation of displacement piles in sand leads to severe changes in the stress state, density and soil properties around the pile tip and shaft, and therefore has a significant influence on the pile bearing capacity. Most current numerical methods predicting pile capacity do not take installation effects into account, as large deformations can lead to mesh distortion and non-converging solutions. In this study, the material point method (MPM) is applied to simulate the pile installation process and subsequent static pile loading tests. MPM is an extension of the finite element method (FEM), which is capable of modelling large deformations and soil-structure interactions. This study utilizes the moving mesh algorithm where a redefined computational mesh is applied in the convective phase. This allows a fine mesh to be maintained around the pile tip during the installation process and improves the accuracy of the numerical scheme, especially for contact formulation. For the analyses a hypoplastic constitutive model for sand is used, which takes into account density and stress dependent behaviour. The model performs well in situations with significant stress level changes because it accounts for very high stresses at the pile tip. Numerical results agree with centrifuge experiments at a gravitational level of 40 g. This analysis confirms the importance of pile installation effects in numerical simulations, as well as the proposed numerical approach’s ability to simulate installation and static load tests of jacked displacement piles.     

A qualitative Natech damage scale for the impact of floods on selected industrial facilities

There is increasing evidence that natural disasters can trigger technological accidents and damage. These so-called Natech accidents can pose a significant risk to regions that are unprepared for responding to them. The European Commission’s Joint Research Centre has recognised the risk associated with Natech events and has started systematic research into Natechs and their underlying dynamics. This work investigates the risk associated with the flooding of industrial installations through an analysis of past case histories and using expert judgement. The potential impact of three levels of flood severity on selected industrial facilities storing and/or processing (eco-)toxic, flammable or explosive materials is analysed qualitatively and a scale is developed that links the flood intensity to the level of potential damage. Our analysis indicates that natural disasters have the potential for triggering hazmat releases and other types of technological accidents. Hence, natural disasters should be considered as separate accident-triggering events in the planning, design and operating stages of industrial facilities that process or store hazardous substances. Our work revealed a lack of detailed information on the occurrence of Natech events which indicates not necessarily a scarcity of Natechs but rather a lack of standardised reporting and record keeping.     

Simplified numerical modelling of pile penetration – the press‐replace technique

This paper presents a simplified finite element analysis technique, the ‘Press‐Replace’ technique, to model pile penetration problems in geotechnical engineering, particularly, pile jacking. The method is employed in standard finite element analysis software. The method involves a straining and a consequent geometry update phase. First, a cone penetration test in (undrained) clay is modelled and compared with the results of analytical, semi‐analytical and more advanced finite element techniques. The model sensitivity for the step size and mesh is investigated using a hypoplastic constitutive model. An optimum way of modelling based on the numerical performance is shown. Copyright © 2015 John Wiley & Sons, Ltd.