水电站砂石加工系统生产废水理工艺试验研究

针对现有水电站砂石加工系统产生的高悬浮物废水的处理工艺存在的排泥系统易堵、沉渣脱水困难的问 题,通过对砂石加工废水中悬浮物的沉降性能、粒径分布和沉渣的脱水性能的相关分析,提出了组合式沉淀工艺处理砂石加工废水.结果表明,成功实现粗细颗粒的分开沉淀,保证一号沉淀池粗颗粒沉渣在90 min内外排是解决沉渣淤池堵管的关键.当控制1、2号沉淀池的总水力停留时间在30 min左右,可基本实现粗颗粒的前端分离,SS去除率可达60％以上,后端经过3号沉淀池的强化絮凝沉淀,出水SS基本可达到污水综合排放标准中的一类排放标准,最终可达到废水处理“零排放”的目的.     

Effects of heat treatment on the physical properties of lightweight aggregate from water reservoir sediment

Lightweight aggregates (LWAs) were produced from water reservoir sediment with added calcium oxide by employing four heat treatments, respectively, at temperatures in the range of 1170-1230 °C. The results show that LWAs produced at temperatures above 1200 °C meet European Union regulation EN-13055-1, which states that the unit weight of LWAs should be lower than 2000 kg/m³. The bulk density was easily lowered by extending the soaking time and increasing the heating rate. The ratio of strength to unit weight of the LWA produced at 1230 °C with a short soaking time and a fast heating rate was near that of a commercial product. The level of water adsorption was below 4%, which increased initially and then decreased due to pore connections and pore sealing. The formation of a glassy phase made the LWAs treated at higher temperature rough and sealed small pores (<0.1 mm) connected to the walls of large pores (>0.2 mm). The mineral phases of the LWAs were quartz, anorthite, and hematite.     

再生骨料混凝土抗氯离子渗透性能研究进展

氯离子侵蚀是影响混凝土结构耐久性的主要因素之一,再生骨料要作结构性材料,须明确再生骨料混凝土的抗氯离子渗透性能.从界面过渡区特征分析了再生混凝土中氯离子的渗透机理,综述了再生骨料取代率、水灰比、掺合料、施工工艺、应力水平等因素对再生混凝土抗氯离子渗透性能的影响,并阐述了再生骨料强化对再生混凝土抗氯离子渗透的改进效果.最后指出需进一步研究多因素耦合作用下再生混凝土的抗氯离子渗透性能.     

轻骨料吸水和返水特性研究进展

近年来,高性能混凝土在各类建筑结构中得到了越来越多的应用,但是自收缩和自重成为了高性能混凝土应用过程中的主要问题,轻骨料(LWA)自身的多孔结构使其具有较普通骨料相比特有的属性—吸返水能力.因此,将预湿轻骨料掺入到混凝土能够对起到内养护的作用,从而改善高性能混凝土自收缩.基于国内外已有的研究成果,本文综述了轻骨料内养护的作用机理和吸返水性能的试验方法.然而,轻骨料的吸水和返水特性研究较少,轻骨料的吸水和返水性能对混凝土的内养护作用仍处于探索阶段.     

基于GM(1,1)的应力损伤轻骨料混凝土抗冻性评估

为在特定灾变程度下,对轻骨料混凝土抗冻融性能进行精确定量描述及预测,通过反复加载对轻骨料混凝土预加初始应力损伤来模拟灾变,以相对动弹性模量为评价指标,研究初始损伤度分别为0、0.05、0.12、0.19、0.27的轻骨料混凝土抗冻融性能;将灰色系统理论引入混凝土抗冻耐久性研究中,利用相对动弹性模量实测数据建立基于GM(...     

再生砖混骨料混凝土柱的小偏心受压性能

通过小偏心受压性能试验对比研究3根的天然骨料混凝土柱和3根同强度全再生砖混骨料混凝土柱,强度分别为C25、C30和C35. 对6根柱进行加载试验,分析再生砖混骨料混凝土柱相比于同强度天然骨料混凝土柱在受力过程、破坏特征、变形能力与承载力等方面的差异. 试验发现,再生砖混骨料混凝土柱在小偏心加载至破坏的过程中,具有与天然骨料混凝土柱相似的3个受力阶段,且符合平截面假定. 与同强度的天然骨料混凝土柱相比,变形较大,但再生砖混骨料混凝土柱的极限承载力略高,原因可能在于两者轴心抗压强度的差异.     

移动设备上Web服务的性能改进

随着移动设备在处理能力方面的迅速发展,内存和存储能力与更高的数据传输率结合在一起,如3G和4G无线技术方面的进步,目前在移动设备上托管Web服务是可行的.在本文中,我们提出了在移动设备上托管Web服务的轻量级框架.并在该框架中进一步对托管RESTful Web服务和基于SOAP的Web服务进行研究和比较分析.实验结果表明,RESTful Web服务对于在有限资源的移动设备上提供Web服务是低资源消耗和高效的.     

再生混凝土墙体墙梁受力性能分析

通过 ３组不同强度等级的再生碎砖混凝土浇筑上部墙体的墙梁、１组烧结砖和砂浆砌筑上部墙体的墙梁试验,研究了再生混凝土墙体墙梁的破坏荷载、应力应变、裂缝、挠度等力学特点。试验结果表明：再生碎砖混凝土墙梁开裂荷载与极限荷载比普通墙梁有所增大;墙梁上部墙体的强度是影响再生碎砖混凝土开裂荷载的重要因素,且其对墙梁的极限荷载也有一定影响;与传统墙梁一样,再生碎砖混凝土墙梁的托梁也为偏心受拉构件;再生碎砖混凝土墙梁的刚度比普通砖砌筑墙梁大,且随上部墙体再生碎砖混凝土强度的增大而增大。     

Evaluation method of cracking resistance of lightweight aggregate concrete

The cracking behavior of lightweight aggregate concrete（LWAC） was investigated by mechanical analysis, SEM and cracking-resistant test where a shrinkage-restrained ring with a clapboard was used. The relationship between the ceramsite type and the cracking resistance of LWAC was built up and compared with that of normal-weight coarse aggregate concrete（NWAC）. A new method was proposed to evaluate the cracking resistance of concrete, where the concepts of cracking coefficient ζt（t） and the evaluation index Acr（t） were proposed, and the development of micro-cracks and damage accumulation were recognized. For the concrete with an ascending cracking coefficient curve, the larger Acr（t） is, the lower cracking resistance of concrete is. For the concrete with a descending cracking coefficient curve, the larger Acr（t） is, the stronger the cracking resistance of concrete is. The evaluation results show that in the case of that all the three types of coarse aggregates in concrete are pre-soaked for 24 h, NWAC has the lowest cracking resistance, followed by the LWAC with lower water absorption capacity ceramsite and the LWAC with higher water absorption capacity ceramsite has the strongest cracking resistance. The proposed method has obvious advantages over the cracking age method, because it can evaluate the cracking behavior of concrete even if the concrete has not an observable crack.     

基于试验二维随机骨料再生混凝土抗压强度研究

制作42个再生混凝土立方体试块并测试其立方体抗压强度,基于二维随机骨料理论推导符合试验用粗骨料级配的二维骨料分布曲线,生成二维随机骨料混凝土有限元模型模拟其抗压强度并与试验结果进行对比.结果表明：再生混凝土抗压强度总体上随再生粗骨料取代率的上升而降低,但再生粗骨料取代率为50%时,试验与有限元模拟结果均存在强度升高的变异现象.随着再生粗骨料取代率的上升,再生混凝土抗压强度峰值应力对应的平均应变有所延后.