新建高速公路沥青砼路面早期损坏分析.doc
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1、 新建高速公路沥青砼路面早期损坏分析摘 要:文章针对新建高速公路沥青砼路面早期出现的损坏,总结其出现的特征,分析其形成的原因,为寻找防治对策提供依据。关键词:高速公路;沥青;砼路面;损坏;分析 作者:黄灿(1976- ),男,壮族,广西远航公路桥梁工程有限公司助理工程师;赵宏志(1975- ),男,壮族,广西南宁航务工程处助理工程师;甘永伟(1975- ),男,壮族,广西路桥总公司第二工程处助理工程师。 一、沥青路面的常规损坏特征及成因 (一)裂缝。纵向裂缝基本平行于道路中心线,距路边缘35m,有时伴随有少量支缝。直线形裂缝主要是大荷载重复作用下产生的,呈弧形且两端向路堤边缘延伸的裂缝主要是因
2、为路基不均匀沉降而形成的。横向裂缝近垂直于道路中心线,间距不等,有时伴随有少量支缝,并逐年增加。沥青面层的低温收缩与半刚性基层收缩裂缝的反应是产生横向裂缝的两个主要原因。同时,填挖交界的差异沉降会产生呈弧形的横向裂缝。网裂的初始形态是在沿轮迹带出现单条或多条平行的纵缝,而后在平行的纵缝间出现横向或斜向连接缝,形成裂缝网,局部伴随沉陷、唧浆现象,它是行车荷载反复作用下,局部结构承载能力不足或过量沉降而产生的。 (二)变形。沉陷指沥青砼路表面的局部凹陷,它是路基沉降或不均匀沉降变形而造成的,或者由于局部开挖后回填土压实不足而造成的,伴随路面的结构形破坏,修补后损坏继续发展。车辙指轮迹带上出现的车槽
3、,外因是渠化交通和荷载作用次数增加,内因是沥青混凝土的高温稳定性荷抗变能力差而产生横向剪切流动变形。推挤变形指在车速频繁变化的路口等处,由于车辆经常刹车和启动,路面在高温和较大水平剪力共同作用下产生的变形。(三)表面损坏。泛油指沥青面层中自由沥青受热膨胀,由于沥青混凝土空隙无法容纳,沥青向上迁移到表面的现象,沥青用量过多、设计空隙率过小、沥青混合料离析使细料过于集中及沥青高温稳定性差是导致泛油的重要原因。泛油发生在天气炎热季节,而天气寒冷季节又不存在可逆过程,影响路面构造深度和抗滑性能。磨光是变面外露的集料颗粒在行车轮胎的摩擦作用下逐渐变光滑的现象。主要原因是在车轮重复作用下,所采用的集料不耐
4、磨而造成。 二、新型损坏现象及成因 (一)新型泛油现象。由点状油斑发展而成的油斑型泛油,多发生载SMA荷开级培沥青混凝土表面层的路面,可分三级:轻,小油斑直径12零星分布;中,油斑增多增大,直径15不等;重,油斑直径、面积或密度增大,逐渐连成片。油斑型泛油具有普遍性,广泛存在于SMA和AK抗滑表面层路面上。它不是由于施工离析原因造成,也不是行驶车辆油料滴落造成。它的成因主要是因为中面层和底面层沥青结合料削落后,沥青向上部迁移至表面层,造成中、底面层失去粘结而松散,表面层沥青富集而泛油。沿车轮迹带分布的带状泛油,拌有少量车辙。它具有普遍性,在渠化交通程度很高的高速公路上,轮迹带被反复再压密,产生
5、带状泛油现象。带状泛油的主要原因:在相对繁重的交通量作用下,沥青表面层被压密,空隙充满沥青;施工时路面压实度不足;所采用的集料质量较差或颗粒棱角、形状、表面纹理较差,矿料骨架在车辆荷载作用下产生位移、再压密而挤压沥青上泛,并伴随有车辙变形。 (二)内部松散现象。传统的松散现象是表面松散现象,是表面沥青与集料的粘附性不足而造成的,其损坏具有整体性。而内部松散现象指路面各层间脱开,中面层大部分和底面层上部松散。在油斑型泛油处无一例外地伴随内部松散现象。 (三)新型泛浆现象。传统泛浆现象是水从裂缝中缓慢渗出,水和细料在重车荷载作用下从裂缝处泵吸出。新型泛浆现象指强大的有压水通过沥青层的空隙,穿透结构
6、完整的沥青面层,基层顶面的浆液通过相同途径被挤压到路表面,泛浆的可能范围是沥青路面的所有透水处。 (四)新型沉陷现象。新型沉陷指基层结合料被不断溶蚀,并被挤压到路表面,造成基层顶面不断脱空,沥青面层随着基层材料的流失而沉陷。沉陷增加,变形增大,导致开裂,水进入并恶化,导致沉陷进一步发展。(五)沥青剥落现象。沥青剥落导致新型泛油、内部松散等病害。沥青剥落存在必然性,程度不同。路面底面层与碱性集料混合料都有沥青剥落现象,沥青混合料空隙率太大,和沥青粘附性不足也容易造成沥青剥落,因此混合料组成设计需要平衡空隙率和粘附性的关系。 (六)坑洞。传统坑洞是沥青蚀粘附性不足,由传统的表面松散现象造成的,坑洞
7、口大底小,发生于表面层的现象。新型坑洞是由于内部松散造成的,与新型泛油有关,坑洞口小底大,发生在沥青路面底层,然后逐渐向上扩展。 三、早期水损坏现象及成因水损坏是指沥青路面在水的作用下,沥青逐渐丧失与矿料的粘结力,从矿料表面脱落,并在车辆的作用下,沥青面层呈现松散状态,以致集料从路面脱落形成坑槽。(一)早期水损坏现象表现为松散、坑洞和唧浆。松散是指沥青与集料相互之间丧失粘结而逐渐酥松直到松垮的现象,主要原因是由于沥青与矿料之间的粘附力不足,在水的作用下,沥青从矿料表面剥落所致。如果施工过程中混合料加热温度过高,致使沥青沥青老化失去粘性,也可能导致松散现象。坑洞是指路面局部松散处集料颗粒逐渐流失
8、而形成的坑洞,它是在水的作用下,细集不断流失而造成的。唧浆是指外界水从裂缝等处渗入,在行车作用下被挤压,从裂缝处唧出的现象,沥青路面裂缝、空隙率过大和基层不耐冲刷导致水不断侵入而造成的。 (二)水损坏的理论解释1.集料沥青的热力学粘附值。机械粘附功:5kcal/mol,因温度变化而异;范德华力:5kcal/mol,因沥青、集料而异。2.集料水的热力学粘附值。氢键力:10kcal/mol,与集料性质有关;范德华力:5kcal/mol,因沥青、集料而异。3.沥青集料表面的固液表面能小于固气表面能,处于部位润湿状态。根据以上分析,集料沥青的界面先天就有被集料水的界面取代的热力学趋势;集料沥青界面处于
9、部分润湿状态客观上为水提供了取代的空间。研究证明:沥青对集料颗粒尖锐的棱角很难裹覆,该处沥青膜非常薄,只有几个分子大小,水可进入,形成沥青矿料水体系。因此,沥青混合料易于在水作用下发生剥落。 (三)水损坏的产生和发展过程。水具有较强的表面张力和湿润性,通过沥青的自发乳化作用并穿透沥青膜侵入集料沥青截面,并最终将其取代。水损坏一般是自下而上的过程1,即由沥青层底部逐渐向上扩展,最终贯穿整个沥青面层造成破坏,与地下水在蒸发压作用和毛细作用下上升有关。表面渗水也有积聚于沥青面层底部的趋势,水损坏在沥青面层底部发展更为严重。水损坏有明显的自愈能力,因而水损坏具有反复性。水损坏最终发展成为松散和坑洞。沥
10、青是从面层下部的集料表面剥落后向上迁移的,造成沥青迁移的原因是车辆水的综合作用,一般发生在夏季或雨季,迁移一直发展下去时造成内部松散。高速行车、水和较大空隙相互作用而产生泛油,造成沥青集料粘附性不足,沥青逐渐削离,形成自由沥青,比重略小于水自然上浮,在轮胎的真空吸力作用下迁移。不均匀是形成斑状泛油的原因之一。沥青迁移的同时,造成内部集料松散,降低整体强度,产生裂缝,形成坑洞。不透水基层顶面长期积水形成泛浆,被冲刷脱空。/Porganization system and working mode, the selection of a number of municipal strengthen
11、ing group to build innovation and strengthen the organization of the basic level organizations advanced model.(seven) the manual work of the Communist Youth League Organization published and League branch of manual work, to promote the use of two manuals in the citys organizations at various levels.
12、 The county committee, directly under the group (work) is under the jurisdiction of grassroots League and group (total) using branch ratio shall not be less than 70%.Three, to further strengthen the groups leadership and team building(a) to strengthen the leagues leadership at all levels of construc
13、tion. Continue to do a good job of municipal Party Committee Organization Department on the strengthening of the Communist Youth League cadres management opinions implementation. To promote the group counties (autonomous counties, cities) Commission and city directly under the group (workers) appoin
14、ted to carry out the Five team building activities. Improve the League Association Department working mechanism. Conscientiously fulfill the duties of CO, combined with the city group directly under (the) Committee of the general election and the adjustment, actively jointly with the unit where the
15、party organization department good group leadership selection with the work. Do a good job in municipal Party committee assistant committee leadership and leading cadres of the annual assessment work, adhere to and improve the assistant secretary of the Communist Youth League talk system group To we
16、ave individual conversation and collective conversation, to strengthen the committees of all levels, the Standing Committee of the Standing Committee, the establishment of a sound system of central group learning, the system of investigation and study, the system of important issues and the reportin
17、g system.(two) to strengthen the work of education and training of cadres to conscientiously implement the Central Committee. On the implementation of grassroots cadres training project and opinions on carrying out the mission municipal CYL Cadres training project implementation opinions, full imple
18、mentation of the project of the City Youth League cadres training education. Focus on the county grassroots cadres and workers focused on training, the new school system vocational training League cadres, for the Municipal Organization Department jointly held the third session of the Communist Youth
19、 League system training cadres in party. Focusing on the construction of new socialist countryside, strengthening village cadres and rural construction team group member of the young team, the county organizations at various levels throughout the year is expected to train 100 00 rural grassroots cad
20、res, plans to train 1000 village secretary of the village Party branch.(three) actively promote grassroots cadres election work. Under the unified leadership of the party organization, to strengthen grassroots organizations direct work, standardize the election work rules and procedures, in the desi
21、gnated candidate, open competition to democratically elected branch secretary at the same time, actively and steadily the development of Township, streets and other grassroots organizations in the direct election of the pilot work, on the basis of summarizing the experience and gradually expand the
22、scope of the pilot, and gradually formed a set of measures and cadres election system.(four) to strengthen the cadres testing exercise. To study the development of XX city from 2006 to 2008 cadres testing exercise planning. To select outstanding cadres to the central mission in Beijing, Shanghai, Gu
23、angzhou and other central organs and sending work in developed areas. With the Central Committee the implementation of the western region and ethnic minorities cadres training plan . To carry out the eighth batch of municipal organs attachment cadre management, selection, training work. The outstand
24、ing cadres to start the National Development Bank XX branch testing exercise.(five) to strengthen the group construction. The main position to play the role of Youth League cadre education and training as the city, in accordance with the requirements of post training, further curriculum scientifical
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