浅埋暗挖法在首钢搬迁工程竖井支护中的应用

首钢搬迁工程旋流井直径大、埋深大,其基坑的开挖和支护不仅要确保边坡稳定,而且要满足变形控制要求.通过旋流井支护方案比选,考虑基坑特点、工程地质条件,采用拱形自撑技术,即浅埋暗挖钢格栅工艺、局部加土钉锚杆喷射混凝土支护方案.采用荷载结构法,经ANSYS有限元计算,降水后,不计水压力作用,结构满足受力要求.给出该支护工艺的关键施工措施,体现土方施工的经济性和施工实践的安全性.     

A Pressure and Temperature Preservation System for Gas-hydrate-bearing Sediments Sampler

A pressure and temperature preservation system (PTPS) was developed for a natural gas hydrates (NGH) sampler. First, some pressure-coring tools for gas hydrate and free gas investigation are reviewed. Then a PTPS with length of 11.2 m and diameter of 60 mm was developed, which can be divided into four parts with a length of less than 4 m for each part. Laboratory experiments showed that this new PTPS was suitable for maintaining the pressure and temperature of ice and water mixture. Further, this new PTPS was applied during the HY4-2006-03 voyage of No. 4 ocean ship on the northern part of the South China Sea, and two pressurized sediments of 85 and 100 cm length were obtained. All laboratory experiments and applications show that the maximum operating depth and sample length of this PTPS are 3,000 m and 10 m, respectively, the PTPS has a good ability of recovering sediment samples on the seafloor and maintaining their original in situ pressure and temperature, meeting the requirement of exploration of NGH in deep-sea shallow sediment layers.     

浅圆仓磷化氢环流熏蒸生产性杀虫试验

主要介绍了浅圆仓环流熏蒸生产性杀虫试验效果.试验表明对不同虫情的粮食,其熏蒸浓度应控制在100～200mL/m3范围,密闭15～25d,可取得较好的杀虫效果.此外,在采用环流熏蒸时,还要考虑产气方式的简便性、经济性等问题.     

Conduction mechanism in antiferrolectric PbZrO3 thin films—analysis of charge carrier trapping phenomenon

Abstract

Antiferroelectric compositions, such as PbZrO₃, are attractive candidates in charge storage devices and actuator/transducer applications in MEMs technology. Thin films of PbZrO₃were deposited on Pt coated Si substrates by a pulsed excimer ablation process. The process of field induced ferroelectric phase switching involves the domain wall reorientation in the polycrystalline thin films. The presence of grain boundaries and various defects in the polycrystalline thin films acts as the pinning sources for the various domain walls. These defects capture the charge carriers in the presence of external applied field and hinders further switching of the dipoles in the domains, thereby increases the response times and threshold voltages for the devices operations. Understanding of the trapping phenomenon in these films is very essential. Using Lampert's theory of space charge limited conduction both shallow and deep trap energies were estimated approximately from charge transport analysis.     

天恒山大断面浅埋土质隧道"两台阶五步"施工技术

当前土质隧道的设计、施工方法很不成熟,导致在建土质隧道施工灾害频发.以在建的天恒山土质隧道为工程背景,针对严寒地区大断面浅埋土质隧道的特点,在改进并革新"三台阶七步"施工法基础上提出了适用于浅埋土质隧道的"两台阶五步"施工法,安全、经济、快速地穿越了天恒山软可塑状态的亚粘土地层.论文详细介绍了"两台阶五步"施工法的技术...     

重钢搬迁项目平基土石方工程标段爆破方案探析

为了满足某重钢项目搬迁所需的技术标准,必须克服各种不利地形,而深挖高填工程数量大、传统施工速度慢、施工效率低下,因而,必须研究推广采用新的爆破技术,确保施工质量。     

大跨度浅埋暗挖洞桩法在地铁施工中的应用

介绍了地铁车站大跨度浅埋暗挖洞桩法的工艺原理及特点,阐述了其施工工艺及方法,分析了施工中的重点、难点及相应的解决对策,实践证明在沈阳地铁车站施工过程中,攻克了施工中的难点,保证了该工程施工期间的地面交通及城市居民的正常生活。     

脆性材料浅裂纹断裂韧度的有限元研究

脆性材料的浅裂纹问题是工程界普遍关注的问题,许多文献的试验表明:脆性材料浅裂纹的断裂韧度低于深裂纹时的断裂韧度,本文通过理论分析和有限元计算,对这一问题进行了讨论。     

浅基础下分层土的地基承载力

本文推导了分层上（包含粘性土、砂土及复合土层）浅基础地基承载力计算的理论解。在此基础上，与一系列国外文献的半经验、实测和有限元等分析结果进行了对比计算和比较，建立了可供设计采用的半经验公式，可以推广应用。     

浅水区静力触探试验应用研究

在水域进行静力触探，至今尚无完整的施工工序与成果应用经验，本文根据在大连、营口等地运用浅水区静力触探试验结果，提出了施工设计，确立了经验公式。根据简易的水上试验方法，现场试验条件，取得了较为经济的离岸试验技术。