软土地区深基坑设计探讨

结合具体工程实例,对软土地区深基坑设计进行了探讨,介绍了软土地基深基坑设计时的荷载取值,设计原则,具体支护方案的选择等,并阐述了支护工程中相关参数的计算软件及程序,以期指导设计人员提高设计水平。     

基于主体功能区的西部地区城镇化发展模式与路径探索

本文从西部地区城镇化发展面临的主要问题入手,探讨了基于全国主体功能区规划下的西部地区城镇化的主导模式选择与路径设计,架构了以主体功能区为基本空间单元的西部地区城镇化多维模式选择框架,并设计出西部地区的"1132"城镇化总体路径,即一个核心--迁转并重,一条主线--多元集聚,三个手段--市场组织、政府规划和环境创新,两支...     

The location and sizing of urban freight loading/unloading lay-by areas

The volume of freight vehicles operating within city boundaries is steadily increasing, which contributes to road congestion, especially in urban areas with a parking deficit. The proper identification of the location and size of commercial parking lay-by areas, where delivery vehicles can park for a limited time to perform loading/unloading operations, can relieve road congestion. Compared to the existing literature, this paper presents an improved two-stage approach, which includes a mathematical programme and a simulation model for determining the location and sizing of lay-by areas. The robustness and soundness of the results from a methodological and practical point of view are discussed using an example application.     

Infiltration Capacity Assessment of Urban Pavements Using the LCS Permeameter and the CP Infiltrometer

This paper presents the Cantabrian portable infiltrometer (CP infiltrometer), a specially designed device based on rainfall simulation for the assessment of the infiltration capacity of all types of urban pavements. Several pervious and impervious surfaces were tested with the LCS permeameter, an existing infiltration test based on the use of a column of water, and the CP Infiltrometer, simulating rain intensities with return periods of 10, 50, and 500 years and 5?min duration. The discussion of the results indicates that the CP infiltrometer could be used successfully to identify different levels of infiltration capacity and to assess the correct performance of pervious surfaces on which design, construction, and maintenance decisions are based.     

Evaluation and Optimization of Bioretention Media for Treatment of Urban Storm Water Runoff

Bioretention is a relatively new urban storm water best management practice. The objective of this study is to provide insight on media characteristics that control bioretention water management behavior. Eighteen bioretention columns and six existing bioretention facilities were evaluated employing synthetic runoff. In columns, the runoff infiltration rate through different media mixtures ranged from 0.28 to 8.15?cm/min at a fixed 15 cm head. For pollutant removals, the results showed excellent removal for oil/grease (>96%). Total lead removal (from 66 to >98%) decreased when the total suspended solids level in the effluent increased (removed from 29 to >96%). The removal efficiency of total phosphorus ranged widely (4–99%), apparently due to preferential flow patterns, and both nitrate and ammonium were moderate to poorly removed, with removals ranging from 1 to 43% and from 2 to 49%, respectively. Two more on-site experiments were conducted during a rainfall event to compare with laboratory investigation. For bioretention design, two media design profiles are proposed; >96%?TSS, >96%?O/G, >98%?lead, >70%?TP, >9%?nitrate, and >20%?ammonium removals are expected with these designs     

Role of Stream Restoration on Improving Benthic Macroinvertebrates and In-Stream Water Quality in an Urban Watershed: Case Study

Many stream restoration projects do not include a requirement for long-term monitoring after the project has been completed, resulting in a lack of information about the success or failure of certain restoration techniques. The National Risk Management Research Laboratory, part of the U.S. EPA Office of Research and Development, evaluated the effectiveness of stream bank and channel restoration as a means of improving in-stream water quality and biological habitat in Accotink Creek, Fairfax City, Va., using discrete sampling and continuous monitoring techniques before and after restoration. This project monitored the effects of a 549 m (1,800 linear-ft) restoration of degraded stream channel in the North Fork of Accotink Creek. Restoration, which was intended to restore the stream channel to a stable condition, thereby reducing stream bank erosion and sediment loads in the stream, included installation of native plant materials along the stream and bioengineering structures to stabilize the stream channel and bank. Results of sampling and monitoring for 2 years after restoration indicated a slight improvement in biological quality for macroinvertebrate indices such as Virginia Stream Condition Index, Hilsenhoff Biotic Index, and Ephemeroptera, Plecoptera, Trichoptera taxa; the differences were statistically significant at 90% level of confidence with the power of greater than 0.8. However, indices were all below the impairment level, indicating poor water quality conditions. No statistically significant differences in chemical constituents and bacteriological indicator organisms were found before and after restoration as well as upstream and downstream of the restoration. The results indicated that stream restoration alone had little effect in improving the conditions of in-stream water quality and biological habitat, though it has lessened further degradation of stream banks in critical areas where the properties were at risk. Control of storm-water flows by placing best management practices in the watershed might reduce and delay discharge to the stream and may ultimately improve habitat and water quality conditions.     

Si nanowires by a single-step metal-assisted chemical etching process on lithographically defined areas: formation kinetics

In this paper, we investigate the formation kinetics of Si nanowires [SiNWs] on lithographically defined areas using a single-step metal-assisted chemical etching process in an aqueous HF/AgNO₃ solution. We show that the etch rate of Si, and consequently, the SiNW length, is much higher on the lithographically defined areas compared with that on the non-patterned areas. A comparative study of the etch rate in the two cases under the same experimental conditions showed that this effect is much more pronounced at the beginning of the etching process. Moreover, it was found that in both cases, the nanowire formation rate is linear with temperature in the range from 20°C to 50°C, with almost the same activation energy, as obtained from an Arrhenius plot (0.37 eV in the case of non-patterned areas, while 0.38 eV in the case of lithographically patterned areas). The higher etch rate on lithographically defined areas is mainly attributed to Si surface modification during the photolithographic process.PACS: 68; 68.65-k.     

基于高密度电阻率法的露天铁矿采空区探测的研究

露天铁矿开采区地下浅部大量采空区的存在,给矿山的人员及生产安全带来极大的威胁。为保证生产活动的顺利进行,必须对采空区进行精确探测。由于高密度电阻率法较常规电法具有信息丰富、精度高的特点,运用该法对露天铁矿采空区进行探测,结合数据反演断面图,在地下50m的范围内,共划定采空区四处,并精确划定采空区顶底板深度、水平范围和展布方向,为矿山的治理工作提供了可靠依据。并且在分析采集数据的基础上,总结出视电阻率识别模型及其主要特点,为地下采空区的划定提供了理论基础。     

南通通州区城乡文化统筹发展的调查与思考

南通市通州区城乡文化的主要发展路径为“六大统筹”,即统筹城乡文化政策设计、统筹城乡文化投入支持、统筹城乡文化设施建设、统筹城乡文化产业发展、统筹城乡文化资源共享、统筹城乡文化队伍建设.尽管通州城乡文化发展成效明显,但是制约当前城乡文化统筹发展的主要问题还比较突出,主要表现在：城乡文化公共投入依然不平衡、城乡文化设施建设依然不平衡、城乡文化资源供给依然不平衡、城乡文化产业发展依然不平衡、城乡文化队伍能力建设依然不平衡.为此,下一步要不断健全政策保障、完善发展机制、创新培育方式、优化发展环境,从而进一步加快城乡文化一体化发展进程.