Measurement of the intrinsic process zone in rock using acoustic emission

Laboratory specimens with a smooth boundary (no notch) were fabricated from four different rock types (grain sizes from 0.1–10 mm) and were tested in three-point bending. The locations of acoustic emission that occurred around peak load were used to characterize the dimensions of the region of localized microcracking, the so-called intrinsic process zone. The size of this zone was found to vary significantly between the rock types, but was not found to vary significantly for different size beams of the same material. An approximately linear relation was found between the width of the intrinsic process zone and the logarithm of the grain size. An explanation of size effect evolves naturally by considering the intrinsic process zone as a material characteristic. Two different models were used to analyze stress at failure. The first treated the intrinsic process zone as a mathematical crack, an infinite stress raiser, from which a K_IC value was calculated. The second model assumed the intrinsic process zone was a cohesive notch, a finite stress raiser, from which the theoretical tensile strength was defined. The second method seemed somewhat better at predicting size effect on nominal peak stress.     

Job accessibility impacts of intensive and multiple land-use scenarios for the Netherlands’ Randstad Area

This paper examines job accessibility impacts of intensive and multiple land-use scenarios in the Netherlands’ Randstad Area for the period 1996–2030. The scenarios involve a heavy increase in the density and diversity of activities around railway stations. Accessibility impacts are examined using location-based accessibility measures and utility-based accessibility benefit measures within a high-resolution land-use/transport interaction modelling framework, taking into account the regional demand for economic activities and possible market responses. It is concluded that extreme concentrations of economic activities at central urban locations well served by public transport are not to be preferred over less heavy concentrations of economic activities at more locations. Heavy concentrations of new firms may firstly repel existing firms in the neighbourhood and secondly result in decreasing marginal returns of accessibility benefits for public transport users.     

中国尾矿坝地震安全度（5）──大石河尾矿坝现场测试成果及各测试方法间的相关研究

本文基于对中国大石河尾矿坝所完成的现场勘察，给出了三种原位测试数据（ＳＰＴ，ＣＰＲ和ＳＷＶ）的分析结果及其相关性研究成果。     

Microanalysis of anionic surfactants in waste water by infrared spectroscopy

Infrared spectroscopy was applied to identify and determine microamounts of anionic surfactants contained in sewage or river waters. The surfactants tested were linear alkylbenzene sulfonate (LAS), branched alkylbenzene sulfonate (ABS), alpha olefine sulfonate (AOS), fatty alcohol sulfate (AS) and fatty alcohol ethoxy sulfate (AES).Anionic surfactants in waters were extracted by chloroform as methylene blue complexes and sulfate type surfactants, i.e. AS and AES were then removed by subsequent hydrolysis. Residual sulfonate type surfactants were first released from methylene blue complexes by ion exchange technique and then changed to sulfonyl chloride derivatives for infrared spectroscopy. Key bands for the identification of sulfonate type surfactants are 640, 618 and 524 cm⁻¹ for LAS, ABS and AOS, respectively. Sulfate type surfactants was calculated from the difference of methylene blue active substance contents before and after hydrolysis.     

冬施混凝土防冻剂选用

简述了碱骨料反应及其反应类型。通过对冬施混凝土防冻剂含碱量的计算，指出了防冻剂对碱骨料反应的影响及造成的危害。     

从信义大厦临街立面改造看高层烂尾楼问题

近年来,越来越多的烂尾楼改造工程受到重视,很多成功的经验表明,烂尾楼的再生利用可以取得显著的经济效益和社会效益。本文以重庆市渝中区朝天门地区信义大厦临街立面改造为例,分析烂尾楼改造的各种相关问题。     

人工现浇楼盖的质量控制措施

本文对现浇钢筋砼楼盖施工前、中、后各阶段为控制质量而应采取的检查措施作了较为详尽的论述，其中特别强调了应保护板面负弯筋不受踩压变形和严格控制拆模时间等措施，从而从根本上保证了建筑物结构的施工质量。值得各有关单位借鉴     

三清山博物馆安全防范工程设计

本文主要讲述了博物馆安全防范系统各子系统的设计,及其各子系统的联动运行,以建立一个比较全面的安全防范系统,达到二级防护设计,满足三清山博物馆安全防范工程需要。     

框架结构层间相对位移变化量在结构损伤检测中的应用

以平面框架为例,通过分析结构的横向柔度,深入研究了局部构件损伤对框架水平位移变化的影响机理特征。基于上述工作,利用框架的层间相对水平位移变化量(RDCSF)作为损伤特征参数,结合神经网络设计,对结构进行损伤检测分析。     

高压喷射沉放结构物施工法与模拟混凝土大圆筒沉放试验

以高压水流冲散结构物壁周土体,使结构物沉降到设计位置,这种方法通过试验,证明是可行的。