Temperature Measurements and Tail Brush Replacement using Frozen Liquid Nitrogen for the Nanjing Weisanlu Tunnel北大核心CSCD

A scheme for stopping water by freezing liquid nitrogen and replacing the tail brush is presented in light of the situation encountered at the Nanjing Weisanlu river-crossing tunnel, a long-distance shield driving tunnel characterized by serious water leakage, sand gushing and water inflow at the shield tail brush. The law of the tempera-ture change of the master outlet circuits and each branch circuit when using liquid nitrogen freezing to stop water un-der high water pressures and the temperature change law for the soil body at different depths are analyzed. The re-sults show that: the temperature difference of the liquid nitrogen is large at the inlet and outlet of the freezing pipe,and it reaches around 35℃ after 6 days; the temperature drops fastest in the pebble layer, and the second fastest in the gravel sand layer, with the temperature cooling slowest in the silty fine sand layer; the average velocities at the frontal surface of the frozen soil in the pebble layer, gravel sand layer and silty fine sand layer are 15.5 cm/d, 12.5 cm/d and 8.3 cm/d, respectively, within the range 600 mm away from the frozen pipe; and affected by heat and air convection in the tunnel, the temperature at the junction of the segment and soil is higher than that in the soil layer.A complete frozen wall takes shape after 13 days of liquid nitrogen freezing, and tail brush replacement takes 22 days from freezing. © 2018, Editorial Office of "Modern Tunnelling Technology". All right reserved.     

Application of Vertical Freezing Technique in the Deep-buried Mountain Railway Tunnel北大核心CSCD

The strata of Chengershan tunnel is mainly consist of the slightly cemented tertiary sandstone, the tun⁃ nel body passes through F 2 fault core zone. Geological disasters of mud outburst, sand gushing and extrusion of work face occurred several times during tunnel construction, so the risks are very high. In view of the core zone of F 2 fault with high pressure and abundant water, a variety of construction schemes were compared and analyzed in terms of technology, feasibility and safety, and vertical freezing technique was used for stratum reinforcement in the railway tunnel for the first time, furthermore the freezing scheme and tunnel support measures were studied, providing refer⁃ ence and guidance for similar tunnel construction.Mountain railway tunnel; Fault zone; Tertiary sandstone; Vertical freezing technique; Application © 2018, Editorial Office of "Modern Tunnelling Technology". All right reserved.     

三塘湖原油注入鄯-兰管线原油物性研究

目前,鄯-兰管线采用加降凝剂改性输送和加热输送相结合的工艺顺序输送塔里木油、哈油、吐哈油及北疆与塔里木混油。三塘湖支线是在鄯-兰管线建成后新建的注入管线,三塘湖原油凝点较高,且降凝剂感受性不理想、稳定性未知。当采用全注入时,需要研究三塘湖原油进入鄯-兰管线后,加热或加剂输送能否安全输送至炼厂;当采用部分注入时,需要研究三塘湖原油与其他原油掺混后物性变化情况,重点研究不加剂三塘湖原油掺入加剂油后物性变化情况。研究方案分为4个时间段,侧重点各有不同,结合鄯-兰管线实际运行情况和注入后对管线的影响两个方面按由急到缓的顺序排定了测试顺序,将为工期相对紧张的相应配套工程开展设计工作提供基础条件。     

电力机车空气管路系统防寒技术

介绍了电力机车空气管路系统目前已采取的防寒措施及存在的问题,从低温环境对管路系统的影响以及防寒工作的重点等方面进行了技术分析,并提出了改进建议。     

饱和多孔介质冻融过程的混合物连续介质理论

应用混合物的连续介质理论,建立了冻融过程中饱和多孔介质的渗流场、应力场和温度场耦合作用的数学模型。该模型以多孔骨架位移、水头和温度为基本变量,包括水总质量守恒方程,总应力平衡方程和总能量守恒方程。该模型可简化为未冻区域内的三场耦合模型,两场耦合的渗流-弹性模型,热-弹性模型和热-渗流模型,以及单场作用的渗流模型,弹性模型和热传导模型。     

应用冻结法加固地铁工程的结构施工研究

主要介绍了上海地铁明珠线蓝村路站-浦东南路站区间隧道联络通道、泵站采用水平冻结加固情况下,隧道支护及结构施工过程,分析了隧道内矿山法施工旁通道对地表及隧道结构产生的影响及解决措施,指出了矿山法施工技术在市政及地铁工程施工中的技术可行性。     

线路重叠交叉段下部隧道联络通道冻结法施工对上部隧道的影响

以某地铁线路隧道重叠交叉段联络通道施工为工程背景,针对下部隧道联络通道冻结法施工,建立Midas/GTS建立三维有限元模型,分析联络通道冻结法施工过程对上部隧道的影响。分析结果表明:下部隧道联络通道施工完成后,上部隧道最大沉降量为-0.322 mm,最大隆起量为0.211 mm,最大水平位移为-0.053 mm,均在安全可控范围内;上部隧道结构最大拉压应力也均满足强度要求。     

冻结法施工地铁联络通道后期渗漏水分析及处置研究

对冻结法施工的地铁联络通道在融沉注浆后仍普遍存在的渗漏水现象,进行了总结归类。深入分析研究了渗漏水发生的各自原因,分别提出了前期预防措施及后期处置方法,并将其在多个联络通道施工中加以应用。工程实践检验表明,这些防漏措施及方法具有较好的工程效果及经济效益。     

地铁隧道联络通道薄弱环节冻结孔布孔方式

地铁隧道联络通道冻结施工的最薄弱环节为隧道开挖对侧顶部区域的冻结。目前,该区域的冻结存在单排长孔冻结和长孔加短排加强孔冻结两种布孔方式。通过对杭州、上海的3个不同布孔方式的地铁联络通道工程现场温度数据的收集,冻结、开挖期间冻结效果的观测,以及钻孔施工情况的分析与对比,发现采用短排加强孔的冻结效果有明显的提升,但是过度密集的布孔可能会造成断管问题的出现。     

短纤维对抗冻劣化特性影响的研究

采用真空成型的手段 ,大大减少了纤维的引气性 ,来研究短纤维对水泥基材料的抗冻劣化性能的影响。冻融实验结果表明 ,短纤维虽然不能完全阻止材料的劣化 ,但是却延缓了冻融破坏的速率。