張俊嶺

(中鐵第四勘測(cè)設(shè)計(jì)院集團(tuán)有限公司設(shè)備設(shè)計(jì)研究處，430063，武漢//高級(jí)工程師)

地鐵乘客在上下車時(shí)有可能接觸到列車車體或站臺(tái)門門體。為有效規(guī)避乘客觸電風(fēng)險(xiǎn)，站臺(tái)門門體需進(jìn)行絕緣設(shè)計(jì)。目前，各地地鐵運(yùn)營(yíng)部門均按照站臺(tái)門對(duì)地絕緣電阻值不少于0.5 MΩ的標(biāo)準(zhǔn)進(jìn)行驗(yàn)收。站臺(tái)門對(duì)地絕緣多采用站臺(tái)門門體的上下立柱連接幾個(gè)絕緣墊作為技術(shù)手段。然而，這是不能絕對(duì)保證達(dá)到絕緣要求的。而且，站臺(tái)門門體的安裝精度及使用壽命會(huì)受到土建及裝修等配合工程的相互作用，繼而影響到門體的絕緣效果。此外，地鐵正式開(kāi)通運(yùn)營(yíng)后，站臺(tái)門門體在實(shí)際運(yùn)行過(guò)程中還會(huì)受到空氣、溫度及濕度變化，以及雜散電流腐蝕等影響，其絕緣阻值也會(huì)不斷下降。

為切實(shí)保障乘客的乘車安全，降低乘客觸電風(fēng)險(xiǎn)，有必要提出切實(shí)有效且適于推廣的地鐵站臺(tái)門門體絕緣方案。

1 站臺(tái)門門體絕緣方案

1.1 站臺(tái)門門體結(jié)構(gòu)

在絕緣問(wèn)題研究初期，曾提出過(guò)站臺(tái)門門體純由樹(shù)脂等絕緣材料構(gòu)筑。這是具備可行性的研究方案。如完全用絕緣材料制作門體，則絕緣效果是超群的，絕對(duì)可以滿足各地地鐵運(yùn)營(yíng)部門的電阻值驗(yàn)收標(biāo)準(zhǔn)。但是，地鐵站臺(tái)門還需承受列車進(jìn)出造成的振動(dòng)，更要將人、車分界，并對(duì)站臺(tái)邊緣起防護(hù)作用，其骨架結(jié)構(gòu)也要具有一定的防火隔斷功能。目前，全絕緣材料構(gòu)筑的站臺(tái)門無(wú)法滿足這些要求。可見(jiàn)，純絕緣材料制成站臺(tái)門門體的方案雖在理論上有可行性，但受限于現(xiàn)有材料技術(shù)，無(wú)法在實(shí)際中應(yīng)用。

只有以金屬構(gòu)件來(lái)作為站臺(tái)門門體骨架才能滿足相應(yīng)的強(qiáng)度及功能要求。目前，以金屬材料作為門體骨架，以絕緣材料作為電阻隔絕層才是最優(yōu)站臺(tái)門門體結(jié)構(gòu)方案。

1.2 絕緣材料性能要求

為真正解決站臺(tái)門門體絕緣的問(wèn)題，作為金屬門體的外裝層，絕緣材料需滿足以下性能要求：

(1)具有極強(qiáng)的附著力。絕緣材料與門體金屬表面必須具有非常強(qiáng)的粘結(jié)力。施工完畢后絕緣材料成為門體金屬不可分割的一部分，在空氣、溫度及濕度變化中，以及運(yùn)營(yíng)使用過(guò)程中不脫層、不斷裂。

(2)具有透明的外觀。加裝絕緣材料后不能影響門體的玻璃隔斷效果，以便乘客判斷乘車候車時(shí)間。

(3)具有極強(qiáng)的耐磨性。由于站臺(tái)門每天啟閉上千次，乘客與門體接觸機(jī)會(huì)也很多，故絕緣材料耐磨性必須相當(dāng)優(yōu)異，以保證在實(shí)際使用過(guò)程中不會(huì)因磨損問(wèn)題而提升觸電風(fēng)險(xiǎn)。

(4)具有抗化學(xué)腐蝕功能。絕緣材料必須具備抗弱酸堿功能、抗老化及大氣腐蝕功能。在正常使用的情況下不會(huì)自然降解或因環(huán)境變化而變性變質(zhì)，更能經(jīng)受保潔人員各種保潔藥劑的腐蝕和摩擦。

(5)材料本身具有安全性。絕緣材料應(yīng)無(wú)毒、無(wú)刺激性氣味，不含有害物質(zhì)(如鉛、鎘、六價(jià)鉻、汞、多溴聯(lián)苯及多溴二苯醚等有害物質(zhì))。

(6)具有防燃燒特性。附著在門體金屬表面的絕緣材料，必須滿足不燃燒或不成為燃燒催化劑的防火要求。

(7)加裝工藝簡(jiǎn)便、經(jīng)濟(jì)。絕緣材料施工最好不需加壓加熱，也不需使用其它專用設(shè)備，以便于推廣和日后的維護(hù)保養(yǎng)。

1.3 絕緣層實(shí)施方案

1.3.1 門體貼膜加裝絕緣層方案

門體貼膜加裝絕緣層方案中，絕緣層以貼膜加裝的方式施工。貼膜技術(shù)是操作簡(jiǎn)便、且透明耐磨的方案。選擇合適的材料也能做到無(wú)毒無(wú)害、抗化學(xué)腐蝕、不易燃燒。

但是在實(shí)際使用過(guò)程中，加裝的絕緣膜體極易受到溫差和濕度變化的影響，常常會(huì)發(fā)生脫膠情況，從而影響絕緣效果。

1.3.2 門體噴涂絕緣涂料

在站臺(tái)門門體表面噴涂絕緣材料同樣是操作簡(jiǎn)便、外觀透明的方案；選用優(yōu)質(zhì)合理的材料也可滿足經(jīng)濟(jì)實(shí)惠的要求，使門體具有無(wú)毒無(wú)害、抗化學(xué)腐蝕、不易燃燒等性能。

但是，由于采用噴涂方式的涂層厚度極小，在實(shí)際使用時(shí)，一旦受到外界環(huán)境變化和人為摩擦很快就會(huì)出現(xiàn)涂層脫落的情況，從而降低絕緣層的絕緣保護(hù)效果。

1.3.3 門體涂刷絕緣涂料

在站臺(tái)門門體涂刷絕緣材料同樣具有操作簡(jiǎn)便、外觀透明的特性。合理選用絕緣材料也可滿足無(wú)毒無(wú)害、抗化學(xué)腐蝕、不易燃燒的限制條件。而且，采用涂刷方式可大大增加絕緣層的厚度，大幅提高其耐磨性。涂刷層對(duì)溫度、濕度變化和人為磨損的抗性也遠(yuǎn)遠(yuǎn)優(yōu)于噴涂層。

1.3.4 使用效果比較

廣州地鐵7號(hào)線(一期)和廣州地鐵6號(hào)線(二期)同時(shí)開(kāi)始運(yùn)營(yíng)。這2條線站臺(tái)門絕緣層分別采用了涂刷和噴涂的方式。當(dāng)6號(hào)線(二期)的站臺(tái)門噴涂層出現(xiàn)部分脫落情況時(shí)，7號(hào)線(一期)的站臺(tái)門絕緣涂刷層粘接依舊牢固。檢測(cè)發(fā)現(xiàn)，絕緣涂刷層電阻值高，綜合性能極為優(yōu)異，其表觀效果與剛施工完成時(shí)高度一致。故選擇涂刷絕緣材料的方案為最優(yōu)方案。

2 施工及運(yùn)營(yíng)對(duì)絕緣層的影響

2.1 施工對(duì)絕緣層的影響

在地鐵建設(shè)施工過(guò)程中，往往會(huì)存在多個(gè)專業(yè)的施工交叉進(jìn)行，甚至有地面露天施工的情況。施工產(chǎn)生的混凝土碎屑、粉塵及水分等會(huì)使門體與大地接觸，從而降低絕緣阻值。

為了預(yù)防此類問(wèn)題，建議站臺(tái)門門體絕緣材料的涂刷工作應(yīng)在大多數(shù)專業(yè)施工完成，且站臺(tái)門門體安裝無(wú)誤的情況下進(jìn)行。這樣可極大規(guī)避施工造成的絕緣層損壞風(fēng)險(xiǎn)。

2.2 運(yùn)營(yíng)對(duì)絕緣層的影響

在地鐵開(kāi)通運(yùn)營(yíng)之后，受地鐵隧道環(huán)境的限制、溫度及濕度變化，以及活塞風(fēng)引起的粉塵會(huì)對(duì)站臺(tái)門門體絕緣產(chǎn)生影響[4]。

在地鐵運(yùn)營(yíng)期間，日常維護(hù)清潔所用的清潔劑也會(huì)對(duì)絕緣層有沖洗、腐蝕作用，進(jìn)而引起絕緣層電阻值的變化，從而影響其絕緣功能。

針對(duì)上述問(wèn)題，建議采用附著力、耐磨性及抗化學(xué)腐蝕等性能更優(yōu)的絕緣材料[6]。

3 最優(yōu)方案實(shí)例分析

基于上述分析，制定了站臺(tái)門門體絕緣層最優(yōu)實(shí)施方案。廣州地鐵7號(hào)線一期工程的9個(gè)車站站臺(tái)門采用最優(yōu)方案，進(jìn)行了工程化試驗(yàn)。

3.1 新型絕緣涂層材料

在涂刷方案實(shí)施中，涂層材料是絕對(duì)的重中之重。目前市場(chǎng)上的絕大多數(shù)涂層都難以滿足金屬門體涂層的基本功能要求。為了滿足全部功能要求，理論試驗(yàn)階段設(shè)計(jì)了涂料新配方，并進(jìn)行化學(xué)合成。經(jīng)多次試驗(yàn)終于得到了能滿足絕緣層全部功能要求的新型絕緣涂層材料。

3.1.1 涂層材料的基本性能技術(shù)參數(shù)

絕緣涂層材料主要化學(xué)成分為納米有機(jī)硅，其合成固化后技術(shù)參數(shù)如表1所示。

表1 涂層材料參數(shù)表

3.1.2 涂層材料特殊性能分析

新型絕緣涂層材料除了要滿足基本性能要求，作為站臺(tái)門涂層還應(yīng)滿足特殊性能要求。

(1)附著力：涂層附著力為12.2 MPa,即粘結(jié)力達(dá)到122 kg/cm2，所以涂層在正常的運(yùn)營(yíng)使用過(guò)程中不會(huì)脫落，與金屬門體粘結(jié)為一體。

(2)耐磨性：涂層耐磨性指數(shù)為0.003 G。該指數(shù)測(cè)試時(shí)采用500 G橡膠砂輪以50 r/min轉(zhuǎn)速運(yùn)轉(zhuǎn)10 min后再計(jì)算磨損量的測(cè)試方式。而絕緣涂層在實(shí)際使用時(shí)一般只有乘客觸碰或衣物摩擦。可見(jiàn)，新型絕緣涂層材料耐磨性能優(yōu)異，完全滿足站臺(tái)門門體絕緣層的耐磨性需求。

(3)電阻率：由表1可知，新型絕緣涂層材料體積電阻率及表面電阻率都很高，其性能優(yōu)異，完全滿足絕緣性需求。

(4)燃燒性能：新型絕緣涂層材料的燃燒性能為B1級(jí)?，F(xiàn)場(chǎng)燃燒試驗(yàn)結(jié)果顯示，該涂層材料涂裝在金屬表面以后，能達(dá)到不燃效果。

3.2 工程化試驗(yàn)

在方案的實(shí)踐效果工程化試驗(yàn)中，進(jìn)行了站臺(tái)門門體(包括安全門每側(cè)24個(gè)活動(dòng)門、端門及應(yīng)急門等)可觸部分基層處理，門體待涂刷部分的表面清潔后，采用新型絕緣材料對(duì)每個(gè)站內(nèi)的站臺(tái)門門體金屬外露不銹鋼表面部分進(jìn)行涂刷。

充分考慮到乘客上下車、候車等待等觸及可能性，涂刷區(qū)域覆蓋了從滑動(dòng)門立柱不銹鋼包板及門楣，到端頭門立柱不銹鋼包板外露于站臺(tái)側(cè)部分，再到滑動(dòng)門、端門與應(yīng)急門軌道側(cè)可與人體接觸的金屬部分。

整個(gè)施工過(guò)程中，施工工藝簡(jiǎn)潔快速。用丙酮或酒精將門體金屬表面清洗干凈后，再用細(xì)羊毛刷將涂料輕輕地均勻涂在金屬表面即可。工期短，也不需要專業(yè)設(shè)備，其施工過(guò)程快速而高效。

施工過(guò)后，涂層均勻透亮，質(zhì)感飽滿，絲毫不影響乘客觀感和地鐵運(yùn)營(yíng)的日常使用，且使站臺(tái)門門體具備反光效果，起到了美化作用。

在工程化試驗(yàn)中，門體絕緣涂層有效減少了門體表面的泄漏電流，增加了門體絕緣電阻。地鐵運(yùn)營(yíng)1 a之后，絕緣層的電阻值均大于100 MΩ，絕緣性能較剛加裝完成時(shí)保持一致；絕緣層沒(méi)有任何損壞，更沒(méi)有脫層起皮現(xiàn)象，其外觀效果與剛施工完一樣透亮。

3.3 工程化試驗(yàn)結(jié)論

工程試驗(yàn)證明，新的絕緣涂層技術(shù)已具備優(yōu)異的性能，不僅克服了傳統(tǒng)金屬表面絕緣層(涂層或貼膜)的附著力低、耐磨性差、易損壞、難以施工及不透明不美觀等弊病，而且不需對(duì)站臺(tái)門結(jié)構(gòu)作任何更改，不影響金屬外觀及質(zhì)感，施工簡(jiǎn)便、工期短。因此，可進(jìn)行工程化推廣?，F(xiàn)廣州地鐵9號(hào)線、13號(hào)線、4號(hào)線南延線及知識(shí)城支線已全部采用該新型絕緣涂層技術(shù)，實(shí)施效果良好。

4 結(jié)語(yǔ)

地鐵站臺(tái)門門體絕緣失效問(wèn)題一直是地鐵建設(shè)的工程隱患。本文對(duì)現(xiàn)行地鐵站臺(tái)門門體的各種絕緣方案進(jìn)行綜合比較，著眼于規(guī)避乘客上下車觸電風(fēng)險(xiǎn)，并結(jié)合工程方案實(shí)施后的客觀效果，提出站臺(tái)門門體涂刷絕緣材料的絕緣改進(jìn)方案，旨在建設(shè)更安全、經(jīng)濟(jì)、便捷高效的城市軌道交通體系。

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(收稿日期：2017-12-19)

(Continued from Commentary)

science and technology of high-speed trains, the introduction stage of high-speed train manufacturing technologies, the digestion, absorption and innovation stage of the imported technologies, and the researching and manufacturing stage of China Standard EMU trains.

The first stage started in "The 8th Five-year Plan" period. During "The 9th Five-Year Plan" period, researching and manufacturing of the high-speed train core components and overall-technology researching of high-speed trains were completed and the core technologies of high speed trains were mastered. On the basis of the above scientific research results, the developing, testing and verifying tasks of the whole high-speed train were carried out during "The 10th Five-year Plan" period. At this stage, the core technologies of high-speed trains grew out of nothing. Its landmark achievements were "China′s Star" and "Pioneer" EMU trains. On September 10, 2002, the highest test speed of "Pioneer" EMU train reached 292.0 km/h. On November 27, 2002, 2M+3T short-marshalling of "China′s Star" EMU train reached the highest test speed of 321.5 km/h. On December 20, 2002, 2M+9T long-marshalling of "China′s Star" EMU train reached the maximum test speed of 305.9 km/h. On the basis of the successful development of the "Pioneer" EMU train, the development of power-distributed high-speed EMU trains of 300 km/h in China was started.

Tackling key problems in science and technology at the first stage cultivated a complete talent team of China in all respects of high speed trains′ theoretical researching, high speed trains′ designing, manufacturing, inspecting and testing etc. At the technical level, the core technologies′ being mastered laid a foundation for the industrialization of the key components of AC drive traction system, computer-control braking system, high-speed gearbox, aluminum-alloy vehicle body, dense coupler, air spring and etc. Meanwhile, all kinds of detect equipment were founded, making detection technology reach the world′s advanced level.

The second stage that started in 2003 introduced high-speed train manufacturing technologies. Thus, the localization of the high-speed trains of "Harmony" CRH1, 2, 3, 5 series was realized, significantly improving railway transportation capacity and passengers′ travel quality, making manufacturing enterprise′s manufacturing ability, level and quality control have a qualitative leap and forming the localization capacity and the industrialization structure. Meanwhile, more comprehensive and deepening understandings for standards, technology, maintenance and application of high-speed trains were achieved. The problems existing at this stage were as follows. The core technologies were controlled by foreign investors, which were enslaved to others. The EMU train models of different technical platforms were too many. There were more than 20 models and the technical platforms and the standard systems were not uniform. For the development of EMU trains, there was lack of perfect top-level designs.

The third stage is the stage of digestion, absorption and innovation for the imported technologies. Its landmark achievements were "Harmony" CRH380 series high-speed trains that were successfully developed in 2010. The deficiencies of the second stage had been improved somewhat at this stage.

The fourth stage, that is, the researching and manufacturing stage of China Standard EMU trains, was begun in 2012. This stage based on the forward design, got rid of the situation of core technologies′ being enslaved to others, set up the standard system of China′s high speed trains, and founded the completely independent technology platforms of China′s high-speed trains. It was the milestone of China′s high-speed train technology development. Its landmark achievement was that "Renaissance" high-speed EMU train with the highest operating speed of 350 km/h commenced commercial operation.

The great significance of developing China Standard EMU trains is as follows. Firstly, China′s EMU sustaining innovation technology platform has been founded. Secondly, the technical standard systems of EMU which adapts to our country′s situation have been formed. Thirdly, China has had the intellectual property rights of high-speed trains. Fourthly, the world-class "producing-studying-researching-applying" innovation teams have been cultivated. Thus, China′s high-speed train technique level′s continuously lying in the world′s advanced rank would be ensured.

Currently, high speed train technologies and its new-type trains are constantly emerging all over the world. For example, there are Germany′s fourth generation Velaro-D high-speed train and the ICE 4 high-speed train, France′s fourth generation new-type AGV high-speed train that adopts permanent-magnet motor traction and is distributed-power, and Japan′s Shinkansen E5, E6 high-speed trains, etc. China is now speeding up to develop China′s new generation intelligent high-speed rail trains, and they will be put into trial operation on Beijing-Zhangjiakou high-speed railway line that will be opened in 2019. We must continue to innovate in the technical aspects of high-speed trains. Only this can ensure that we continue to be in the first square team to keep up with the world′s advanced level and to achieve the higher goal of leading technology.

(This paper is the summary of the author′s keynote speech at "2018 Urban Rail Transit Development Forum and The Academic Forum of 20th anniversary ofUrbanMassTransitMagazine′s Starting Publication" on the May 17, 2018.)