Waterproofing Technology of Underground Subway Tunnels

The waterproof construction of subway tunnels is a crucial and challenging aspect of subway tunnel engineering.Mastering excellent waterproof construction technology is essential to ensure that the construction meets design requirements and guarantees the safe operation of subway lines.This paper focuses on discussing waterproof construction technology for subway station tunnels.By analyzing the main methods and techniques of underground tunnel construction,as well as the key techniques and difficulties of waterproofing construction,this paper examines the waterproofing construction project of Guangzhou Metro Culture Park Station as a case study.It analyzes the methods,quality management practices,and safety management strategies applied in the project.This paper serves as a reference for tunnel engineering design and construction units in our country,offering insights into effective waterproof construction techniques for subway tunnels.

New Problems of Boiler Corrosion after Coupling Combustion of Coal and Biomass and Anti-Corrosion Technologies

This study explores the corrosion issues arising from the coupled combustion of coal and biomass and proposes potential solutions.Biomass,as a renewable energy source,offers advantages in energy-saving and carbon reduction.However,the corrosive effects of alkali metal compounds,sulfur(S)and chlorine(Cl)elements in the ash after combustion cannot be underestimated due to the high volatile content of biomass fuels.We investigate the corrosion mechanisms,as well as the transfer of Cl and alkali metal elements during this process.Comparative corrosion analyses are conducted among coal-fired boilers,pure biomass boilers and boilers with coupled combustion.Various biomass types in co-firing are studied to understand different corrosion outcomes.The main factors influencing corrosion include the physicochemical properties of biomass feedstock,furnace temperature and heating surface materials,with the chemical composition and ash content of biomass playing a dominant role.Currently,the methods used for anti-corrosion include water washing pretreatment of biomass feedstock,application of novel alloys and coatings and the development of additives to inhibit fouling,ash deposition and corrosion.Efficient inhibitors are economical and easy to produce.Additionally,biomass can be converted into biomass gasification gas,although challenges related to tar still need to be addressed.

Preparation and Performance Study of Cementitious Capillary Crystalline Waterproof Materials

Cementitious capillary crystalline waterproof materials(CCCW for short)offer durability and excellent waterproofing properties,making them a popular option for building waterproofing.Some scholars have studied the proportioning of such materials.However,these studies lack the relationship between the impermeability pressure of mortar and the components,and the mechanism of action is somewhat debatable.Therefore,we adopted a two-step method in our experiments.Firstly,we screened out the components that significantly impact impermeability from a variety of active components by orthogonal test.We then optimized the design of the active group ratio using the simplex lattice method.Lastly,we conducted a performance test of the optimal ratio and explored the waterproofing mechanism of homemade CCCW.

Application of New Concept Waterproofing in Xiang'an Undersea Tunnel,China

As a kind of transportation mode for crossing channels, undersea tunnel has incomparable advantages for its directness, convenience, fastness, insusceptibility to weather conditions, and smaller influences on environments. In recent years, with the development of undersea tunnel construction, the design and construction technologies have been greatly enhanced. The first undersea tunnel in China has just been built. Waterproofing is the key technique of undersea tunneling. A new concept of waterproofing scheme of grouting, sealing, draining and divided sections was adopted in the construction of the tunnel based on the researches, the in-situ geological features, the astuteness of the current technology and the cost of construction. The structural details of the sealing and draining system are introduced to illustrate the salient features of the new waterproofing technique. It is hoped that experiences described in the paper can offer guidance for the construction of the extensive undersea tunnels in the coming years.

Development of anti-corrosive coating on AZ31 Mg alloy subjected to plasma electrolytic oxidation at sub-zero temperature

Plasma electrolytic oxidation(PEO)is a promising surface treatment to generate adherent and thick anti-corrosive coating on light-weight metals(Al,Mg,Ti,etc.)using an eco-friendly alkaline electrolyte.High energy plasma,however,inevitably generates porous structures that limit their practical performance.The present study proposes a straight-forward simple method by utilizing sub-zero electrolyte(268 K)to alter the plasma characteristics during formation of the protective coating on AZ31 Mg alloy via PEO with a comparison to the electrolyte at room temperature(298 K).In refrigerated electrolyte,the formation of micro-defects is suppressed relatively at the expense of low coating growth,which is measured to be twice lower than that at 298 K due to the temperature-dependent soft plasma discharges contributing to the development of the present coating.As a consequence,corrosion resistance of the sample processed at 268 K is superior to that of 298K,implying that the effect of coating thickness is less dominant than that of compactness.This phenomenon is interpreted in relation to the ionic movement and oxide solidification controlled by soft plasma discharges arising from the temperature gradient between electrolyte and surface of the substrate during PEO.

Study on Preparation of Waterproofing Agent for Mineral Wool Board from Modified C_9 Petroleum Resin

The modified petroleum resin emulsion prepared from the C9petroleum resin was modified with maleic anhydride.The effects of maleic rosin and maleic anhydride addition level,the modification time and the alkali liquor on the properties of the emulsion were discussed.The results showed that the optimum process conditions covered:a maleic anhydride mass fraction of 1.5%,a maleic rosin mass fraction of 10%,a KOH mass fraction of 1%,a petroleum resin modification temperature of 200℃,a petroleum resin modification duration of 3 h,and a modified petroleum resin emulsion/wax emulsion mixing ratio of 1:1.The particle size of modified petroleum resin emulsion prepared under these conditions was equal to 104.166μm.

Synthesizing Self-Crosslinking Waterborne Polyurethane-Silanol Dispersion for Waterproofing Application

Polyurethane dispersions (PUD) have diversified into a myriad of applications over the years. This has led to extensive research on both industrial and laboratory fronts as polyurethane dispersions provide liberty to interplay at the molecular level to diversify the properties of the product which has also led to the development of eco-friendly waterborne dispersions. Yet, waterborne PUDs are limited in their mechanical and physical properties as compared to solvent-based products. The incorporation of crosslinkers in the PUD further bolsters these properties thus improving water and solvent resistance. The incorporation of silanols increases solvent resistance and adhesion of the resultant PUD. In this work, a post crosslinking system based on the ketone-hydrazine mechanism was incorporated into the PUD thus providing the required structural reinforcement for construction application. The targeted application for this work is the use of PUDs for waterproofing.

Bonding strength of graded anti-corrosive coatings of fluoroethylenepropylene (FEP)/polyphenylene sulfide (PPS)

Fluororesin-based anti-corrosive coatings including graded FEP/PPS were prepared on carbon steel by melt powder coating, the bonding strength of all coating systems was determined by the pull-off test. It is found that the poor adhesion of fluororesin coatings to metallic substrates is improved obviously by the graded coating structure of FEP/PPS, and the bonding strength reaches up to 11.8 MPa for the five-layer system. Examination by electron probe microanalysis （EPMA） verifies that the distribution of main components is graded in the five-layer system, which is responsible for the enhancement of the interfacial bonding.

Elastic Bio-based Polyurethane Nanofibrous Membrane with Robust Waterproof and Breathable Properties

Elastic bio-based waterproof and breathable membranes(EBWBMs) allow the passage of water vapor effectively and resist the penetration of liquid water,making it ideal for use under extreme conditions.In this study,we used a facile strategy to design the bio-based polyurethane(PU) nanofibrous membranes with the nanoscale porous structure to provide the membranes with high waterproof and breathable performances.The optimization of nanofibrous membrane formation was accomplished by controlling the relative ambient humidity to modulate the cooperating effects of charge dissipation and non-solvent-induced phase separation.The obtained EBWBMs showed multiple functional properties,with a hydrostatic pressure of 86.41 kPa and a water vapor transmission(WVT) rate of 10.1 kg·m^(-2)·d^(-1).After 1 000 cycles of stretching at 40% strain,the EBWBMs retained over 59% of the original maximum stress and exhibited an ideal elasticity recovery ratio of 85%.Besides,even after 80% deformation,the EBWBMs still maintained a hydrostatic pressure of 30.65 kPa and a WVT rate of 13.6 kg·m^(-2)·d^(-1),suggesting that bio-based PU nanofibrous membranes could be used for protection under extreme conditions.

Preparation of low-cost waterproofing materials

To address the need for producing a cheap,single-component,hot-applied compound joint sealant with high quality for sealing joints and cracks in concrete and flexible pavements without using primer for installation,a hot-applied modified asphalt sealant was produced by blending up about 30% starch into 20% citric acid.The starch and the asphalt cement were mixed at a temperature of above 160 ℃.Thus the waterproofing asphalt was manufactured to protect the surface of various shapes and types from water leakage using the citric acid.Results indicate that this sealant complies with the requirements of ASTM D-1191,D-6690-06a and D-7116-05.The citric acid is a kind of reliable materials for asphalt cement,which can be widely used in paving and waterproofing construction materials,and this offers profound engineering and economic advantages.

Anti-Corrosion and Reconstruction of Surface Crystal Plane for Zn Anodes by an Advanced Metal Passivation Technique

For the aqueous Zn-ion battery,dendrite formation,corrosion,and interfacial parasitic reactions are major issues,which greatly inhibits their practical application.How to develop a method of Zn construction or treatment to solve these issues for Zn anodes are still great challenges.Herein,a simple and cheap metal passivation technique is proposed for Zn anodes from a corrosion science perspective.Similar to the metal anticorrosion engineering,the formed interfacial protective layer in a chemical way can sufficiently solve the corrosion issues.Furthermore,the proposed passivity approach can reconstruct Zn surface-preferred crystal planes,exposing more(002)planes and improving surface hydrophilicity,which inhibits the formation of Zn dendrites and hydrogen evolution effectively.As expected,the passivated Zn achieves outstanding cycling life(1914 h)with low voltage polarization(<40 mV).Even at 6 mA cm^(−2) and 3 mA h cm^(−2),it can achieve stable Zn deposition over 460 h.The treated Zn anode coupled with MnO_(2) cathode shows prominently reinforced full batteries service life,making it a potential Zn anode candidate for excellent performance aqueous Zn-ion batteries.The proposed passivation approach provides a guideline for other metal electrodes preparation in various batteries and establishes the connections between corrosion science and batteries.

深埋岩溶隧道爆破开挖对围岩损伤及渗流特性的影响

深埋岩溶隧道开挖会造成围岩特殊的损伤破坏形式,并且损伤区也会影响围岩渗流场及隧道边界的涌水状况,对深埋岩溶隧道爆破开挖作用下围岩的损伤及渗流特性有重要的研究意义。为了研究爆破开挖对深埋岩溶隧道围岩损伤及渗流的影响规律,基于COMSOL Multiphysics软件建立数值模型并嵌入应力-渗流-损伤耦合方程式进行计算,采用解析法计算了简化条件下岩溶隧道开挖时围岩的应力分布,并与数值计算结果进行比较。结果表明:解析法与数值法计算的围岩应力分布有一致性,爆炸荷载使靠近溶洞侧隧道肩部及脚部区域会产生较大的拉应力;爆破后会在隔水岩柱形成“齿”状损伤区,同时引起肩部及脚部区域流速的增加,其可作为判断溶洞方位的参考依据;溶洞净距减小、洞径及水压增加会引起“齿”延伸倾角及最大涌水位置变化、隧道边界涌水量的增加,可根据“齿”延伸方向判断损伤区检测的合理方位,根据最大涌水位置变化、隧道边界涌水量的变化,合理调整涌水防治措施强度及重点防治部位。研究成果可为溶洞位置判定、隧道损伤区检测以及边界涌水防治措施提供参考。

页岩储层防水锁聚合物水基钻井液体系研究

开发一种适用于页岩储层的水基钻井液体系,以优化钻井过程中的页岩稳定性和防水锁效果。通过页岩滚动回收率、线性膨胀率测试以评价不同处理剂的效果。结果表明:0.5%WEDM+1.5%SFTH复配体系可显著提高页岩的回收率,同时最大线性膨胀率由37.6%降至16.80%。封堵剂CMS在控制滤失量方面表现出色,包被剂KPAM在提高钻井液稳定性和降低滤失量方面具有显著效果。防水锁水基钻井液配方为:4%基浆+1.0%WEDM+1.5%SFTH+1.5%CMS+0.3%KPAM+2.0%op-10。该体系在高温高压条件下展现出了优异的流变特性和滤失控制能力,特别是在抗温性和抗污染性方面表现卓越。该体系在150℃高温下保持了良好的稳定性,且对NaCl和CaCl_(2)的抗污染能力强。在储层保护方面,该体系能有效减少钻井液对储层的伤害,实现高达85.69%的渗透率恢复率,同时形成的泥饼质量良好。研究成果对于页岩气开采具有重要意义。

高耐水聚合物水泥防水涂料及其应用性能研究

从JS防水涂料的耐水机理出发,针对性地设计了由聚合物中活性官能团(羧基)与交联剂形成的后交联结构,减弱了水分子对聚合物分子间的增塑作用及对聚合物分子与无机填料界面力的破坏作用,研制了一种具有优异耐水性能的JS防水涂料。该涂料在长期浸水后,仍保持较好的物理力学性能,吸水率<9%、拉伸强度>1.6 MPa,且浸水1年后表观无变化。

城市轨道交通装配叠合整体式地下车站防水关键技术

[目的]为提高装配叠合整体式地下车站的防水性能,助力其在城市轨道交通工程中的应用,需对此类型地下车站的防水关键技术进行研究。[方法]对装配叠合整体式地下车站的混凝土抗裂防渗技术、外包防水方案及细部构造防水方案等进行了研究。[结果及结论]预制板墙构件开裂风险较大位置主要为厚度分别为500 mm和350 mm的结构表面,以及厚度为100 mm的结构中心和表面;预制顶板降温速率不宜大于2.2℃/h;预制墙板水蒸气养护由45℃降至10℃的时间不宜小于24 h,降温速率不宜大于1.5℃/h;叠合结构体系中,以受拉为主的构件宜采用水洗露骨料施工工艺,以受剪为主的构件宜采用凿毛施工工艺;温度场调控与膨胀历程调控可有效降低混凝土开裂,提高车站防水性能;车站主体结构外包防水方案,后嵌式圆形压缩密封条设计,压缩密封节点湿埋收头,以及预制板在牛腿位置的黏结措施等防水方案,提高了车站节点的防水性能。该方案在锡澄线南门站的成功应用,对于促进此类型地下车站在城市轨道交通工程中的应用,以及缩短施工工期、提升劳动生产效率、促进建筑产业转型升级等具有促进作用。

盾构隧道管片接缝内外双道密封垫防水性能试验研究

为探究螺栓孔防水对内外双侧布置双道密封垫防水体系的影响,依托某超大直径盾构隧道工程,自主设计新型双道密封垫防水性能测试装置,开展考虑螺栓孔构造的内外双道密封垫防水体系耐水压测试。研究结果表明:1)螺栓孔对内外双侧布置双道密封垫的整体防水性能具有一定的控制作用,当螺栓孔防水能力不足时,其存在将成为内外双道密封垫防水体系的薄弱环节,可能早于内道密封垫发生渗漏,由此降低内外双道密封垫防水性能较单道密封垫的提升水平;2)当螺栓孔防水性能达到要求后,与单道密封垫相比,内外双侧布置双道密封垫防水体系的防水能力大幅提升;3)对于超大直径盾构隧道,当管片接缝采用内外双侧布置双道密封垫时,应确保螺栓孔防水性能满足双道密封垫间的协同防水要求。

钻爆法公路隧道防排水技术发展综述

为研究钻爆法公路隧道防排水技术的发展趋势和未来方向,系统梳理了防排水技术的发展历程、技术要求、设计施工和维护技术等内容,并对需要关注的问题及下一步发展方向进行展望。结果表明:按照隧道建设的技术发展水平,防排水技术可划分为圬工时代和后混凝土时代,已实现原则指导、设计优化、材料革新、施工控制、标准保障及运营维护的基本构架;中国在新修订的规范中增补了隧道渗漏水量化标准,使防水等级规定更具客观性、科学性;从防排水系统构造形式的对比情况看,控制排水型隧道能兼顾隧道衬砌水压力和维护隧道区生态平衡等多方面需求;钻爆法隧道防排水技术虽然增加了一些可维护性设计,但仍以功能性设计为主,且现有技术难以满足防排水系统的维护需求。应当注意:防排水技术是一个系统性问题,需要建立基于全寿命周期的建管养一体化防排水体系,并对防排水系统选型和控制型防排水技术进行系统性研究,通过对全寿命周期内隧道排水的环境影响进行分析评价,确定合理的防排水构造型式;另外,需加强防排水系统优化及新工艺研究,加快新型防排水材料的开发;同时要加强维护技术研究,尤其是可维护性技术和修复性技术研究。

上海地铁运营车站出入口底板改造防水技术探讨

上海地铁运营线网中,有为数不少的车站出入口缺少下行自动扶梯,根据相关部门要求,上海地铁已开展了一部分出入口的加装扶梯改造,并计划未来几年覆盖全网;加装扶梯过程中,有部分出入口需要局部开挖结构底板增设扶梯基坑,施工风险较大。以此类涉及出入口改造项目为例,介绍运营车站出入口底板改造中的防水关键技术,以期为今后同类型改造项目的防水设计提供借鉴。

脱硫石膏强度及耐水性改善方法研究综述

针对脱硫石膏强度及耐水性改善方法和改性机理做了系统的归纳与分析。详细阐述了水泥、各种矿物掺合料、有机硅防水剂以及其他有机乳液等对脱硫石膏及其复合胶凝材料的强度和耐水性的影响,对各种改性方法的作用机理、优点以及不足之处进行了讨论。结果表明:掺入适量的水泥和矿物掺合料时会生成水硬性产物,脱硫石膏的强度和耐水性得到一定的改善,但是掺入过量时会造成不利的影响;水泥、粉煤灰和脱硫石膏之间的比例变化会对胶凝体系的强度和耐水性产生较大的影响;有机硅防水剂可以在脱硫石膏表面形成一层疏水性薄膜,显著提升脱硫石膏的耐水性,当与矿物掺合料复合作用于脱硫石膏时可以得到更好的力学性能和耐水性能;其他类型的有机防水剂均能改善脱硫石膏的耐水性,但是大部分会改变脱硫石膏的晶体形貌,对脱硫石膏的强度和耐水性产生不利影响;目前脱硫石膏的改性材料都比较复杂,单独作用时综合性能不佳,需要进一步研究与探讨更加简单、有效的改性材料和方法。

包覆交联法提升玫瑰茄红上染真丝织物色牢度的应用

文章以甲基丙烯酸甲酯、丙烯酸丁酯、2-羟基乙基甲基丙烯酸酯和甲基丙烯酰氧丙基三(三甲基硅氧烷基)硅烷为原料,合成了聚丙烯酸酯类高分子,再将整理后的织物浸于戊二醛溶液中,以达到化学接枝交联的目的,并将其作为纤维包覆材料应用于天然玫瑰茄红色素染色的真丝织物。实验结果表明:整理后真丝织物的色牢度明显提升,湿摩色牢度从2~3级提升到4级,皂洗色牢度从1~2级提到3~4级,并且整理后织物表现出较好的防水效果,水接触角从接近0°提到125°;机械性能显著改善,断裂强度从8.73 MPa提高到26.37 MPa。