Reliability Analysis of Ultimate Bearing Capacity of Concrete Filled Tube High Piers     

XU Teng fei  ZHAO Ren  XIANG Tian yu  YANG Cheng 《保鲜与加工》2010,(2):60-63

To deal with the contradiction between accuracy and time consuming, a model of reliability analysis of CFT was proposed based on the response surface and nonlinear finite element method, And Initial geometric imperfection was induced by consistent mode imperfection method.The reliability index and sensitivity coefficients of CFT high piers were invested by the proposed model.The effects of slenderness, eccentricity and diameter thickness ratio on reliability index of concrete filled tube high piers were studied by parameter analysis method.Meanwhile, the influence of geometric nonlinearity was also analyzed and the reliability of CFT high pier could be affected by factors mentioned above.Based on the analysis, several suggestions for improving the reliability of CFT high piers were proposed.  相似文献   

Test on Seismic Behaviors of Reinforced Concrete Beams Composite Rehabilitation with Bonded Carbon Fiber Reinforced Polymer and Steel Plate     

LIAO Shao-huai  LU Yi-yan  CHEN Dao-fan 《保鲜与加工》2010,(6):14-21

Neither the Carbon Fiber Reinforced Plastic nor the steel plate strengthening concrete components shows sufficiency in improving the structures' seismic behaviors independently, while they complement each other by the way of composite strengthening. Six reinforced concrete beams, five of which are strengthened, were comparatively and experimentally tested under low frequency cyclic load to investigate their mechanical performances such as characteristic of resilience, hysteretic curve, seismic behaviors, skeleton curve, degeneration of rigidity and loading capacity. It is indicated that the way of composite strengthening can boost the beams′ ultimate bearing capacity, ductility and deformability capacity effectively, and it can delay rigidity degeneration and improve the seismic behaviors of the beams. Also, the CFRP and steel plate can work together very well.  相似文献   

Structural Noise Analysis of Longitudinal Stiffened Concrete Cylindrical Shell in Air     

SUN Liang ming  Xie Wei ping 《保鲜与加工》2010,(3):41-45

Structural noises induced by urban viaduct box beam basically comes from the vibration responses with low frequency noises, which may affect the surrounding buildings’ security, the common using of high precision instruments and the living of human beings etc.In order to study the principles of structural noise of railway box beams, the infinite longitudinal stiffened concrete cylindrical shell in air was actively investigated.Aimed at the fluid structure interaction, the characteristics of sound radiation of coupling system were investigated by the wave number domain approach and transfer matrix method.And the effects of various parameters on the properties of concrete cylindrical shell, including the position of observation point, the size of the external excitation force, structural damping and the amount of longitudinal ribs, were numerically simulated based on the proposed analytical model.It is found that the increase of longitudinal ribs can effectively reduce the vibration and structural noises of concrete cylindrical shell.The observations would be provided as beneficial guidelines for the noise mitigation of pipeline structures and railway box beams.  相似文献   

氯离子诱导的钢筋混凝土结构耐久性研究     

王显利  孔庆银 《吉林林学院学报》2010,(3):267-273

从影响氯离子传输的因素、临界氯离子浓度、氯离子向混凝土内传输的机理、氯离子传输预测模型等方面对因氯离子诱导的钢筋腐蚀造成的钢筋混凝土（RC）结构耐久性能退化问题进行了评述,提出了需要进一步研究的问题.  相似文献   

公路水泥混凝土路面设计中的问题探讨     

宋高嵩  于晓坤  徐闯 《东北林业大学学报》2005,33(1):87-88

结合交通部新颁布的公路水泥混凝土路面设计规范和公路路面设计中存在的问题,对设计参数和标准的选择进行分析论证,提出了合理的路面设计思想和方法。  相似文献   

An innovative stabilization/solidification treatment For contaminated soil remediation: demonstration project results     

Petra Scanferla  Giorgio Ferrari  Roberto Pellay  Annamaria Volpi Ghirardini  Gabriele Zanetto  Giovanni Libralato 《Journal of Soils and Sediments》2009,9(3):229-236

Background, aim, and scope

An innovative stabilization/solidification (S/S) process using high-performance additivated concrete technology was developed for remediating soil contaminated by metals from abandoned industrial sites. In order to verify the effectiveness of this new ex situ S/S procedure, an area highly contaminated by metallic pollutants (As, Cd, Hg, and Pb), due to the uncontrolled discharge of waste generated from artistic glass production on the island of Murano (Venice, Italy), was selected as a case study. The technique transforms the contaminated soil into an aggregate material suitable for reuse as on-site backfill. This paper reports the main results of the demonstration project performed in collaboration with the local environmental protection agency (ARPAV).

Materials and methods

An ex situ treatment for brownfield remediation, based on the transformation of contaminated soil into very dense, low porous, and mechanically resistant granular material, was set up and tested. Specific additives (water reducers and superplasticizers) to improve the stabilized material properties were developed and patented. A demonstration plant assembled on the study area to treat 6 m³ h^–1was then tested. After excavation, the contaminated soil was screened to remove coarse material. The fraction Ø?>?4 mm (coarse fraction), mainly composed of glass, brick, concrete, and stone debris, was directly reused on site after passing through a washing treatment section. The highly polluted fraction Ø?≤?4 mm (fine fraction) was treated in the S/S treatment division of the plant (European patent WO/2006/097272). The fine fraction was mixed with Portland cement and additives defined on the basis of the high performance concrete technique. the mixture was then granulated in a rolling-plate system. After 28 days curing in an onsite storage area to allow for cement hydration, the stabilized material was monitored before its in situ relocation. The chemical, mechanical, and ecotoxicological reliability and performance of the treatment was checked. Metal leachability was verified according to four leaching test methods: Italian Environmental Ministry Decree (1998), EN 12457 (2002) tout court, amended only with MgSO₄ and, lastly, with artificial sea water. The mechanical properties were measured according to BS (1990) and AASHTO (1999) to obtain the Aggregate Crushing Value and California Bearing Ratio, in that order. Moreover, leachate samples prepared with artificial seawater were assessed via the Crassostrea gigas embryotoxicity test and Vibrio fischeri bioluminescence inhibition test to discriminate the presence of potential ecotoxicological effects for the brackish and saltwater biota.

Results

Outcomes from all leachate samples highlighted the effectiveness of the remediation treatment, fully complying with the Italian legislation for non-hazardous material reuse under a physicochemical viewpoint. The stabilized granular material demonstrated high mechanical strength, low porosity, and leachability. Moreover, ecotoxicological surveys indicated the presence of low toxicity levels in leachate samples according to both toxicity tests.

Discussion

Remediated soil samples revealed a significant decrease in leachability of heavy metals as a consequence of the application of additivated cement that enhanced granular material properties, resulting in improved compactness due to the reduction in water content. The toxicity data confirmed this state-of-the-art technique, indicating that leachates could be deemed as minor acutely toxic.

Conclusions

The proposed S/S treatment proved to be able to remediate soil contaminated by heavy metals through trapping pollutants in pellet materials presenting adequate physicochemical, mechanical, and ecotoxicological properties in order to prevent leachability phenomena, their reclamation, and reuse being made easier by its granular form.

Recommendation and perspectives

This project foresees long-term monitoring activity over several years (until 2014) to consider treatment durability.  相似文献   

耕作方式对耕层土壤结构性能及有机碳含量的影响   总被引：25，自引：2，他引：23  

许淑青  张仁陟  董博  张鸣 《中国生态农业学报》2009,17(2):203-208

为了寻求能够提高土壤结构稳定性的耕作模式,在陇中黄土高原半干旱区连续7年的定位试验研究基础上,采用常规分析方法(湿筛法、重铬酸钾容量法、环刀法),研究了不同耕作方式对耕层土壤结构性能及有机碳含量的影响.结果表明:与传统耕作(T)相比,免耕无覆盖(NT)、传统耕作+秸秆还田(TS)和免耕+秸秆覆盖(NTS)3种保护性耕作方式均能不同程度地增加耕层土壤的有机碳和不同粒径水稳性团聚体的含量,其中免耕+秸秆覆盖(NTS)处理效果最佳.在0～10 cm土层中,NTS处理的土壤容重低、孔隙度大,土壤结构得到了较大改善.不同耕作方式下0～5 cm、5～10 cm和10～30 cm土层粒径1～0.5 mm水稳性团聚体的含量最高,粒径>0.25 mm水稳性团聚体含量与有机碳含量和孔隙度呈显著正相关,与容重呈显著负相关.  相似文献   

寒区渠道防渗工程优化模式研究     

徐淑琴  王丽学  宋军 《灌溉排水学报》2004,23(4):67-70

通过对国内外灌区渠道防渗工程模式和新材料、新设备应用情况的调查了解,以及黑龙江省19个大型灌区渠道防渗工程现状分析,规划了适合寒区特点的防渗方案,并使重点方案在试验区进行2年对比试验,同时对各试验方案的优越性进行了模糊判定,提出了适合寒区气候特点并适应地区经济发展水平的各级渠道防渗工程的优化模式干、支渠素土膜料的模式为最佳,其次为边坡混凝土膜料、底素土膜料分区护砌模式;斗、农渠混凝土U形槽模式为最佳。  相似文献   

方形截面钢管混凝土套箍系数与延性指标的关系     

孙耀东  刁绍起  刘学艳  陶忠 《东北林业大学学报》2004,32(4):78-79

对12个方形截面钢管混凝土(以下简称为方钢管混凝土)轴向压缩的荷载一变形关系进行了试验研究,考察了不同套箍系数下方钢管混凝土的延性指标,证明了钢管对核心混凝土约束的有效性。  相似文献   

Effects of soil aggregate size on phosphorus extractability and uptake by rice (Oryza sativa L.) and corn (Zea mays L.) in two Ultisols from the Philippines     

Hoang Thi Bich THAO  Thomas GEORGE  Takeo YAMAKAWA  Ladiyani Retno WIDOWATI 《Soil Science and Plant Nutrition》2008,54(1):148-158

  相似文献