基于正交试验和神经网络的复合固结土强度预测

以固化剂、石灰、水泥复合固结土为研究对象,采用正交试验的方法进行复合固结土7 d无侧限抗压强度试验的配合比设计,并完成正交试验。针对正交试验结果,采用人工神经网络的方法建立复合固结土强度试验结果的预测模型,通过控制强度试验的配合比指标,训练确定预测模型的模拟函数,从而实现对剩余部分试验结果的预测。研究结果表明,采用正交试验和神经网络相结合的方法,预测复合固结土强度,预测结果准确,误差不超过2.3%。     

水泥-过磷酸钙复合材料固化铅污染土的浸出和力学特性

水泥是铅污染土固稳修复常用的固化剂,在修复重度铅污染土时效果较差。而过磷酸钙在稳定铅污染土方面具有溶出风险低、长期稳定性好和环境安全性高的优点。为了研究水泥-过磷酸钙复合材料固化后铅污染土的浸出和力学特性,采用水泥-过磷酸钙复合材料对铅污染土进行固化/稳定化处理,通过浸出试验、无侧限抗压强度试验和渗透试验对固化前后的铅污染土固化体进行浸出和力学特性变化特征对比分析,分别探讨了水泥和过磷酸钙添加量对固化土浸出和力学特性的影响规律。结果表明:水泥可显著改善铅污染土的强度和渗透特性,当水泥的添加量从5%增加到30%时,固化土的抗压强度从0.56 MPa增加到4.78 MPa;渗透系数从8.2×10-7cm/s减小到2.2×10-8cm/s。但水泥在固稳高浓度铅污染土效果较差,当水泥的添加量从5%增加到30%时,固化土的浸出浓度从56.3 mg/L减少到19.8 mg/L,固化土的浸出浓度远高于我国危险废弃物鉴别标准(GB/T 5085.3—2007)。过磷酸钙可显著降低污染土中铅的浸出特性,固化土的浸出浓度从43.5 mg/L减少到0.17mg/L;但过磷酸钙会降低固化土的力学性能。随着过磷酸钙添加量从1%增加到5%,固化土的抗压强度从1.17MPa降低到0.42 MPa;渗透系数从3.0×10-7cm/s增加到1.3×10-6cm/s。因此,在铅污染土实际工程中应根据实际的场地工况和修复目标,合理选择水泥和过磷酸钙的配比,保证修复后的铅污染土强度特性和浸出特性均满足修复标准。     

浅谈我省旧路技术改造中路面设计

为了适应交通运输的需要,我省的旧有公路急待升级和技术改造,现简谈几点有关旧路技术改造路面设计问题。 一、路面设计时除考虑路面整体强度外还应念其各结构层强度。根据路基路面综合调查结果表明,有些路面弯沉大者早破坏。这说明弯沉值的大小不能完全反映路面的真实强度,半刚性基层石灰加固土、水泥加固土、石灰水泥综合加固土、水泥稳定砂砾等使用和推广更集中暴露出不能光用一个弯沉指标来控制,特别是对不同的路面结构层采用一个弯沉指标,并不符合各自结构层次的真正破坏条件。为了真实的反映路面实际破坏状态,在做好合理的结构组合设计前提下,除以总弯沉为控制路面整体强度的设计     

膜袋水泥土在北汝河岗马险工护岸工程的应用

介绍膜袋水泥土在北汝河岗马险工护岸工程的应用,总结施工工艺及质量控制要点,以期为其他类似工程提供参考。     

水泥混凝土配合比施工质量的要求与控制

主要从水泥混凝土配合比设计要点出发,讨论了水泥混凝土施工质量控制的关键环节以及水泥混凝土配合比的控制方法。     

水泥稳定碎石基层施工质量的控制

从水泥稳定碎石底基层施工质量出发,分析了水泥稳定碎石底基层施工质量的影响因素,阐述了水泥稳定碎石底基层施工质量控制的方法:选择高质量的原材料、设计原材料的混合比例、严格水泥稳定碎石底基层施工步骤。     

复合地基加固法中的CFG桩的设计与应用

从复合地基的基本概念、分类、加固机理出发,着重阐述复合地基加固法中的CFG桩的加固机理、适应范围、设计原则及计算方法、施工工艺选择和质量检验。提出在公路工程软土地基处治中可采用CFG桩,并得出CFG桩施工工艺简单、适应范围广,所用材料是在碎石桩的基础上加入少量的水泥和粉煤灰,受力特性与水泥搅拌桩类似。它可用于杂填土、饱和及非饱和粘性土、粉土、砂性土及湿陷性黄土地基中,以提高地基承载力和减少地基变形。只是当原地基承载力标准值fk≤50kPa时其适用性值得考虑。若以挤密或消除液化为目的时,采用CFG桩是不经济的。     

水泥混凝土路面断板的影响因素分析

水泥混凝土断板控制的好坏直接影响到道路的使用年限.本文详细阐述了水泥混凝土路面断板的影响因素,指出水泥混凝土路面断板既有施工控制原因,也存在自然环境、设计、养护等方面原因.针对各影响因素采取有效技术和防范措施,降低水泥混凝土路面断板现象发生.     

浅谈公路水泥稳定碎石基层施工中的质量控制

对水泥稳定碎石基层施工中的原材料控制、水泥剂量控制、摊铺、碾压、养生、接缝等进行了论述,阐明只有严格按照规范和设计施工才能有效地保证基层的整体质量。     

浅谈水泥稳定碎石基层施工质量控制的措施

通过宁杭高速公路水泥稳定碎石基层施工实践,介绍了控制水泥稳定碎石基层施工质量的具体做法,对水泥稳定碎石基层施工各环节质量控制重点、存在问题及影响因素进行了分析,提出了相应的控制措施。     

卧式水泥窑窑体安装工法

水泥窑是水泥生产装置的核心设备,其安装难度较大,质量要求较高,特别是窑体安装的直线度和窑体的焊接变形是水泥窑安装控制的关键,本文就黑龙江省桦南县鸿基水泥厂2500t/d水泥窑安装工程进行介绍水泥窑窑体的安装工法,供参考。     

Dendrochronological analysis of the growth and growth-climate relationships of conifers in the region of alkaline dust deposition

Relationships between climate and radial growth of Oxalis-Myrtillus-site type Norway spruce and Scots pine stands under different cement dust loads were investigated. Dendrochronological methods were used. Long-term alkaline (pH 13.2-12.7) dust pollution emitted over 40 years from a cement plant was the reason of alkalisation (pH 7.8-8.1) and high concentrations of K, Ca and Mg in soil of affected territories. Two study sites, Kunda and Malla (2.5 and 5.0 km E from the emission source), were influenced by the dust emissions of the cement plant. Two other study sites, Eru (38 km W) and Revoja (34 km W), were situated on a relatively unpolluted area and served as control sites. The relationships between the radial growth and climate were almost similar on the control and dust-polluted sites. The climatic variables that had a significant effect on the radial growth of Norway spruce at both control and polluted sites were the temperature and precipitation of summer months of the current and preceding years. Specific to the Scots pine stands growing under dust pollution was a significant positive impact of the current spring temperature on the radial growth. A positive effect of precipitation during winter months on the radial growth was found at all sites. A significant negative effect of cement dust on the radial growth of Scots pine stands during the period of large amounts of dust emission (1966-1991) was detected. The effect of cement dust emissions on the radial growth of Norway spruce stands was also negative but weak. The decrease in the dust emissions since 1992 improved the growth conditions at pine stand sites.     

水泥混凝土路面加铺沥青混凝土技术质量控制

旧水泥混凝土路面加铺沥青混凝土面层是一种特殊的路面结构,其应力、应变特性与一般的弹性层状体系有较大的差别,质量控制涉及到旧水泥混凝土板的处理、反射裂缝的防治、加铺层厚度控制、面层材料的选择、提高路面的抗渗性能等关健环节。     

浅谈水泥砼路面平整度的提高

结合国道301线刘秀屯至尚志路段一期工程水泥砼路面的施工,分析影响砼路面平整度的因素,介绍现行水泥砼路面合理的施工工艺,提高控制水泥砼路面平整度的水平。     

Changes in the canopies of Pinus sylvestris and Picea abies under alkaline dust impact in the industrial region of Northeast Estonia

Studies were carried out in 1999, 2005 and 2007 in the area of Kunda cement plant in Northeast Estonia on sample plots 3 km W and 2.5 and 5 km E of Kunda. As control stands, two plots for pine and spruce were established in Lahemaa National Park (34-38 km W of Kunda). The selected pine and spruce stands were 75-85-year-old Myrtillus site type, of 0.7-0.8 density and II quality class, with moderately dense or sparse understorey. The values concerning needle density and number of needle scars were higher for shoots formed in the period of higher pollution than for the shoots grown under a considerably lower pollution load. Although the cement dust pollution has notably decreased from year to year, the number of needle pairs per 1 cm of the shoot was 1.8-2.1 times greater in the shoots formed in 1998 than in those formed in 2003, whereas the changes were statistically reliable. Possibly the low temperatures at the time of shoot and needle formation affected the density of needles on all sample plots, and thus the number of needles on shoots formed in 2003 was many times smaller. After the significant fall in the pollution load since 1996 the length growth of needles intensified around Kunda cement plant, at the same time no changes occurred in the length growth of needles in the control area. As compared to the data from 1998, the length growth of pine needles had improved, especially 2.5 and 5 km E from the cement plant, needles being respectively 1.5 and 1.1 cm longer than 6 years ago. The stimulation of the growth of pine and spruce needles 2.5 and 5 km E of the cement plant may be a sign of a positive effect of reduced doses of cement dust in soil. The greater length of pine and spruce needles is the reason for the larger biomass of the needles.     

碳酸盐法制水泥稻草板的研究

采用施加释放二氧化碳的添加剂，近似于普通刨花板的热压工艺，利用正交试验对水泥稻草板的快速固化工艺进行试验：讨论了水灰比、草灰比、添加剂用量对板子性能的影响。结果表明：水泥稻草板的快速固化工艺可行，添加释放二氧化碳的碳酸盐制板的最佳制板工艺参数为：草灰比1：6，水灰比0．5，碳酸氢钾为水泥加量的10％。     

浅谈沥青混凝土路面施工管理

本文阐述了如何控制沥青混凝土路面施工质量和控制施工质量的方法。