硬塑性黏土区管桩浮桩分析及处理

在硬塑性黏土区采用预应力管桩,容易造成管桩上浮现象,应慎重选择预应力管桩;针对预应力管桩上浮问题,可采用复压、桩端压密注浆、桩间补打柔性桩复合地基、补钻孔灌注桩等措施处理。文章结合工程实例,采用钻孔灌注桩补桩处理预应力管桩上浮现象,解决浮桩造成的预应力管桩承载力不足问题,并有效地控制了两种桩型的沉降差。     

静压预应力管桩在非整合土层区域的施工质量控制措施

静压预应力管桩在非整合土层区域施工过程中,容易出现桩身上浮、高断桩率和桩位偏移的质量问题,为保证工程质量,本文通过工程实例,分析预应力管桩的沉桩机理,介绍静压预应力管桩在非整合土层区域的施工质量控制措施。     

软土地区预应力管桩浮桩问题浅析及质量控制措施

预应力管桩因其施工简便、成本低廉、工效高、工期短等优点在工程中得到了广泛的应用,但其在软土地区中经常遇到浮桩的问题,给桩基质量与工程安全带来隐患。通过泉州地区某工程实例,对预应力管桩浮桩原因作出了分析,得出浮桩与桩径、桩距,地下条件、土体性质及施工顺序等因素有关,并提出了质量控制措施。     

软土地基管桩挤土浮桩与处理方法

介绍了预应力混凝土管桩在应用中存在的问题,分析了软土地基管桩浮桩的成因。结合工程实例,进行了管桩静载荷试验,对试验结果进行了分析,总结了处理浮桩的技术措施。     

软土地基管桩浮桩分析与处理方法研究

针对某广场在高强预应力管桩施工中出现大量浮桩的现象,研究了软土地基中管桩浮桩对桩侧阻、端阻和承载力的影响.通过对浮桩进行注浆和复打两种处理方法的对比研究表明,在软土地基中处理管桩浮桩应优先采用复打措施.文章研究成果对类似工程具有借鉴意义.     

某工程静压预应力管桩断桩事故分析及纠正预防措施

预应力管桩是一种新型桩基础,但由于施工技术经验不足,在软弱土应用过程中容易出现桩身倾斜、浮桩、断桩等质量问题。本文通过某工程实例,分析预应力管桩断桩事故原因,并提出相应的纠正和预防措施。     

浅析轻艺大厦基桩上浮及补强处理

随着现今社会的不断迚步与发展,建筑行业也得了充足的发展。目前建筑工程基础采用预应力骱强混凝土管桩的应用广,但预应力骱强混凝土管桩在地层中经常逖到浮桩现象,浮桩成为桩基工程施工质量控制的重点和难点。本文结合具体工程实例,从桩基施工过程中的浮桩情况迚行分析,并送过静载试骋上浮桩提出有效的处理措施,供同行参考。     

软土地区管桩浮桩现象与加固方法研究

针对沿海软土地区某工程在预应力管桩高应变法检测过程中大面积发现疑似浮桩现象,采用静载、低应变法等手段进行了比对分析,探讨了预应力管桩上浮的影响因素和上浮规律,提出了解决预应力管桩上浮的加固处理方法。研究结果表明,在软土地区选用管桩基础时,可采用高应变法初步判断其是否存在浮桩现象;对存在深厚淤泥土层等情况应因地制宜、慎重选择桩型;采用复打法能有效的处理管桩上浮问题,建议优先采用自由落锤复打结合高应变法监控方式,研究可供类似工程参考和借鉴。     

饱和粘性土地区管桩施工质量问题探讨

预应力混凝土管桩施工工程,在饱和粘性土地区,连续快速施工,挤土效应产生超孔隙水压力,导致桩身上浮,引起管桩单桩竖向抗压极限承载力大幅度降低,不能满足设计要求。具体表现:管桩单桩竖向抗压极限承载力低,离散性大。出现此情况的管桩基础属于不合格工程,不经再次设计加固处理补救,桩基不能应用。经复压处理满足设计要求后,可以投入使用。     

预应力管桩后注浆处理技术在工程中的应用

通过实际工程案例,阐述了在深厚饱和黏性土地层中,预制管桩快速沉桩所可能造成的严重危害,即大面积浮桩现象。通过现场试验数据显示,严重的桩基上浮,致使单桩静载试验值远低于预计的桩基承载力设计要求。针对已发生的浮桩问题,现场制定并实施了预应力混凝土预制管桩后注浆加固处理方案。结果显示,管桩后注浆处理技术可有效消除浮桩引起的不利影响,大幅度提高管桩单桩承载力。     

抗浮锚杆施工工艺的探讨

基于抗浮桩在高层建筑和深基坑工程抗拔力应用中存在不足的改进,将湿作业法、跟管作业法等引入抗浮锚杆设计施工工艺中,与传统抗浮桩施工相比,采用抗浮锚杆施工工艺的质量、工效、成本更合理,以及施工工艺选择的重要性及合理安排设备的必要性,值得推广应用。     

地下车库上浮事故分析与加固处理

近年来,由于抗浮设计和施工处理不当,造成地下车库出现上浮,底板、顶板及柱出现裂缝的工程事故时有发生。本文通过某工程实例,根据施工设计图纸资料和现场施工情况的调查分析,发现了事故产生的原因,并提出了抗浮整改措施与加固处理方法,取得了良好的效果。     

某坡地建筑地下室抗浮疏水设计方法

针对坡地建筑地下室抗浮设计问题,本文提出采用疏水设计方法,该方法既解决了坡地建筑地下室较难准确确定抗浮水位取值的问题,又可节省工程造价并缩短施工工期,是一种绿色技术,该方法可供同类工程抗浮设计参考。     

辽宁新邱废弃矿山环境治理中浮煤残煤回采研究

新邱露天煤矿矿区环境治理是阜新市目前最大的民生工程,通过该项目的实施,可以改变矿区及周边生态环境恶劣的现状,同时因地制宜地构建和恢复宜人宜居的生态环境。其中,浮煤、残煤自燃治理是矿山环境治理的一个重要环节。结合矿区地形地貌,进行勘察规划设计,利用三维模型以及采矿技术手段掌握矿区浮煤、残煤分布情况,进而利用3D模型通过3D-MINE软件估算浮煤、残煤保有储量。探讨研究应用单斗卡车采掘工艺清理浮煤、削坡清理边坡残煤自燃煤层,既消除了浮煤、残煤自燃产生的火灾,又有效地回采浮煤、残煤。新邱露天煤矿矿区环境治理中浮煤、残煤的回采利用对其他露天煤矿环境治理有一定借鉴意义。     

美人蕉和菖蒲生态浮床净化微污染源水的比较

利用美人蕉和菖蒲生态浮床净化微污染源水,在进水TN为0.91～1.17mg/L、TP为0.12～0.18mg/L、CODMn为5.48～9.36mg/L、DO为3.6～6.1mg/L时,两种生态浮床的出水水质均能满足集中式饮用水水源地水质标准(GB3838—2002)的要求;其中美人蕉和菖蒲浮床对TN的平均去除率分别为42.5%和36.2%,对TP的平均去除率为48.1%和44.2%,对CODMn的平均去除率为42.3%和36.3%,美人蕉浮床的净化效果要好于菖蒲浮床。可见,生态浮床的除污效果较好,可用于微污染源水的净化。     

大型罐区构建大流量液氮泡沫系统的探讨

针对我国大型浮顶储罐的发展趋势,指出移动式大流量消防炮与远程供水系统是国外处置大型储罐全面积火灾的主要方式。研究了固定式和移动式液氮泡沫灭火系统在我国大型罐区的应用方式,根据液氮泡沫在全尺寸油盘上的喷射与灭火试验结果,指出在罐顶集中布置泡沫喷射器有利于全面积火灾扑救。考虑到我国大型储罐的分布特点和数量,移动式大流量液氮泡沫灭火系统与储罐半固定式泡沫喷射系统结合是最适合于我国应对大型储罐全面积火灾的方式。     

Detection of Legionella spp. and some of their amoeba hosts in floating biofilms from anthropogenic and natural aquatic environments

Floating biofilms develop at the water-air interface and harbor numerous microorganisms, some of which are human pathogens like Legionella pneumophila. The presence of Legionella spp. and especially L. pneumophila in such biofilms was investigated. In parallel, the occurrence of Naegleria spp., Acanthamoeba spp., Willaertia spp., Vahlkampfia spp. and Hartmanella spp. was determined and it was examined whether Acanthamoeba spp. isolates were naturally infected with L. pneumophila bacteria. Eight anthropogenic and 37 natural aquatic environments were sampled between June and August 2005. Both Legionella spp. and L. pneumophila were present in 100% of the floating biofilms of the anthropogenic aquatic systems. Eighty-one percent of all natural floating biofilm samples were positive for Legionella spp. and 70% of these samples were positive for L. pneumophila. Legionella concentrations were in the range of 10(1)-10(2)cells/cm(2). Naegleria spp. and Acanthamoeba spp., two well-known L. pneumophila amoeba hosts, were present in 50-92% and 67-72% of floating biofilm samples, respectively. Acanthamoeba spp. isolates appeared to be naturally infected with L. pneumophila bacteria as proved by fluorescent in situ hybridization.     

浅析西安城市边缘区流动人口特征及住房条件

通过对西安市城市边缘区的流动人口进行实地调研,对流动人口的特征和住房条件进行了分析,指出城市必须完善流动人口管理法规,建议建造流动人口公寓,从而改善流动人口的居住质量。     

Methylmercury in water, seston, and epiphyton of an Amazonian river and its floodplain, Tapajós River, Brazil

Levels and accumulation of MeHg were characterized in filtered water, suspended organo-mineral matter, phytoplankton, zooplankton and epiphyton during the dry season and the wet season. In open water of the lentic and lotic ecosystems, the MeHg in filtered water (< 0.2 microm) was near or below the detection limit (< 0.02-0.03 ng/l). These concentrations represent < 5% of the Hgtot. content in filtered water. Inundated forests (Igapó) and macrophyte floating mats were the only sites where MeHg was significantly detected (0.07-0.24 ng/l), representing 3-22% of the Hgtot. in filtered water. MeHg concentrations in organo-mineral suspended matter (2-26 ng/g dry wt. representing 0.6-7.3% of Hgtot.) were correlated with the N content but not with the C content. Data suggest that MeHg enrichment of suspended matter is strongly influenced by the presence of degraded planktonic remains relatively rich in N and MeHg. In zooplankton, MeHg concentrations (20-140 ng/g dry wt.) increased from the dry season to the end of the wet season. This increase was followed by higher proportions of MeHg during the wet season in comparison to the dry season (15-40 to 50-70% of the Hgtot.). The epiphytic material collected from the roots of macrophyte floating mats contained 2-8.5 ng/g dry wt. of MeHg. The proportion of MeHg to Hgtot. in epiphyton (1.5-8.3%) correlated with its C and N contents. The data suggest a greater bioavailability of MeHg in the Tapaj6s River ecosystems due to the seasonal increase in water level and the consequent inundation of the floodplain. Inundation favours the development of large macrophyte floating mats which increases the bioavailability of epiphyton to herbivorous/detritivorous fish. The root zone of floating macrophytes and the flooded organic horizon of the Igapó forest are the only sites along the Tapajós River where significant MeHg can be detected in the water column and sediment. This new study supports the hypothesis that MeHg production and transfer to the first link of the food chain in Amazonian river systems is closely related to organic matter biogeochemistry in the floodplain environment.