Pressure Tight Piston Corer ——A New Approach on Gas Hydrate Investigation

A pressure tight sediment samphng technology, which can be introduced into the modification of the piston corer to accommedate the investigation of gas hydrate, is put forward. In this paper, the three basic rules of the technology are analyzed in detail: specimen transferring rule, seal self-tightening rule and semi-active pressure holding rule. Based on these, the structure of the pressure tight piston corer is put forward and its working principle is analyzed. Finally, a pressure tight sediment sampler, to which the same technology is apphed, is researched through experiments. Results show that the sampler based on the above-mentioned theory has a good ability in samphng and in -situ pressure holding.     

某斜柱式栈道旅游安全评价

旅游景区栈道由于设计、施工技术资料不详,并经常发生超员现象,存在安全隐患。结合案例工程,根据结点连结方式不同,建立斜柱式栈道力学分析模型。按照实际栈道调查,分别对八种模型在相应荷载下的弯矩、轴力和剪力对比分析,发现最大弯矩和剪力出现在水平横粱上,最大轴力出现在斜支撑上,进而提出栈道最不利内力验算模式。评价认为要保证其结构安全,须确保游人在栈道上单列行走并保持间隔在0．5m以上。但考虑旅游实际需要可增设斜支撑。     

Analysis of a kinematic self‐centring seismic isolator

This investigation deals with the analytical formulation and experimental validation of a prestressed reinforced concrete seismic isolator with kinematic constraints at both ends. The kinematic isolator was proposed initially as a low‐cost solution for seismic protection of low‐income people housing usually placed at the periphery of big cities where regular to bad soil conditions are common. So, the isolator is also a pile foundation with a central prestressed cable and two rolling steel surfaces at the top and bottom ends. By varying the shapes of the end rolling surfaces, different force–deformation constitutive relationships for the isolator may be obtained. Energy dissipation is introduced by yielding of passive reinforcement at the rolling interphase. Apart from stating the large‐deformation formulation of the element, several relevant aspects of the behaviour of these devices are studied herein, such as the increase in the tension of the central prestressed cable, responsible for the self‐centring action of the isolator, the floor uplift that results from the geometry of the isolator, and the vertical stability of the system. Experimental and theoretical results obtained for a group of 9 testing specimens show an excellent agreement in the force–deformation constitutive relationship. Although not the intent of this article, the device proposed may be extended directly as a coupling beam element for shear wall systems. Copyright © 2006 John Wiley & Sons, Ltd.     

240B型柴油机机破原因分析

针对某机务段２４０Ｂ型柴油机机破事故中的破损件连杆及连杆螺栓进行解剖,通过断口电镜分析、金相分析、化学成分及机械性能试验得出,机破是由于曲轴连杆颈碾瓦后,连杆大头端颈面出现裂纹导致疲劳断裂造成的。     

钻杆接头表面高功率CO_2激光硬化行为的研究

利用正交试验法研究了高功率ＣＯ２激光工艺参数对钻杆接头表面硬化效果的影响，利用显微硬度计测定了硬化层硬度的分布规律及组织特征，采用计算机回归处理分析得出了Ｐ、Ｄ、Ｖ、Ｅ对硬化层面积大小因子ｈ·ｂ影响的表达式。研究结果为高功率ＣＯ２激光强化钻杆接头提供了一定的依据     

皖南山区高路堑边坡的综合处理

主要介绍皖南山区采用浆砌片石护坡、支撑渗沟、喷射混凝土锚杆、浆砌片石护面墙等方法联合加固公路深路堑边坡的成功经验.     

玻璃幕墙安装施工测量及其控制技术

以南京某大楼幕墙施工测量的实践为例,详细介绍了幕墙安装施工测量的主要技术要点,即：建立外围控制网、墙上控制点、楼内轴线控制点,建立水平和垂直视准线以及特殊位置幕墙龙骨的定位放样。提出了轴线投测后点位和外墙高层控制点必须建立相互联系以便进行校核和调整,对幕墙工程施工有一定的指导意义。     

微型钢管桩在基坑支护中的应用

随着经济社会的快速发展,微型钢管桩作为一种支护结构在深基坑支护施工中的应用越来越多。本文根据微型钢管桩的施工工艺以及工程实践,总结了微型钢管桩应用于基坑支护工程的主要特点,结合工程应用实例分析了微型钢管桩在基坑支护工程中的作用及效果,表明在基坑周边环境条件受限和抢险加固等基坑支护工程中能充分发挥微型钢管桩的优点,具有显著的经济效益和社会效益     

Groundwater recharge in the Akaki catchment,central Ethiopia: evidence from environmental isotopes (δ18O, δ2H and 3H) and chloride mass balance

Recharge patterns, possible flow paths and the relative age of groundwater in the Akaki catchment in central Ethiopia have been investigated using stable environmental isotopes δ¹⁸O and δ²H and radioactive tritium (³H) coupled with conservative chloride measurements. Stable isotopic signatures are encoded in the groundwater solely from summer rainfall. Thus, groundwater recharge occurs predominantly in the summer months from late June to early September during the major Ethiopian rainy season. Winter recharge is lost through high evaporation–evapotranspiration within the unsaturated zone after relatively long dry periods of high accumulated soil moisture deficits. Chloride mass balance coupled with the isotope results demonstrates the presence of both preferential and piston flow groundwater recharge mechanisms. The stable and radioactive isotope measurements further revealed that groundwater in the Akaki catchment is found to be compartmentalized into zones. Groundwater mixing following the flow paths and topography is complicated by the lithologic complexity. An uncommon, highly depleted stable isotope and zero‐³H groundwater, observed in a nearly east–west stretch through the central sector of the catchment, is coincident with the Filwoha Fault zone. Here, deep circulating meteoric water has lost its isotopic content through exchange reactions with CO₂ originating at deeper sources or it has been recharged with precipitation from a different rainfall regime with a depleted isotopic content. Copyright © 2006 John Wiley & Sons, Ltd.     

避雷针(带)保护范围的计算

通过一工程实例,对屋面避雷针(带)保护范围的计算方法进行探讨。由于对滚球法的基准面选取不同,从而影响到最终计算结果。