Overhaul of Beijing section
Shi Jing expressway Beijing Section starts from the Third Ring Liuli Bridge and ends at Liulihe River, with a total length of 45.6 kilometers. 1986 was completed and 1993 was opened to traffic. With the increase of traffic volume year by year, pavement aging and bridge and culvert damage are becoming more and more serious, and single-board dangerous bridges are increasing year by year. Several slab bridges are constantly being rebuilt and updated. In order to completely eliminate potential safety hazards and meet the requirements of fast, safe and comfortable driving in expressway, with the approval of the Municipal Transportation Commission, the company will carry out overhaul in expressway, Shi Jing in two years, and the third ring road to the fifth ring road will be overhauled and afforested simultaneously. In 2005, the overhaul tasks of Liuliqiao-Zhaoxindian section of the Third Ring Road (two-way access to Beijing) and Zhaoxindian-city boundary section (one-way access to Beijing) were completed.
1. The overhaul project from the Third Ring Road to the Fifth Ring Road is planned from April to August 10.
The main road overhaul project started on April 13 and is expected to end on July 3 1 day. The construction time starts at 2 1 in the evening and ends at 6: 00 the next morning. The construction method is to close half the lane at night and the other half lane, so as to ensure the two-way traffic of the main road and the auxiliary road, and to be fully open during the day. In order to reduce the impact of construction on traffic, the slab replacement construction of 16 two-way approach bridge was completed two weekends before and after May Day. It is planned to complete the elevation lowering construction of Xidaokou 1000m section from May to June 20th. The construction time is 24 hours day and night. The construction method is to close half the traffic day and night, and use auxiliary roads to partially divert vehicles.
The overhaul and greening project of the auxiliary road started on May 9th and was completed on August 10. Pave asphalt concrete at night, and the rest work will be interspersed.
2. The overhaul project from the Fifth Ring Road to the city boundary is scheduled to start from May 10 to August 3 1.
The section from the Fifth Ring Road to Zhaoxindian started on May 10 and was completed on July 3 1. During the construction period, half of the lanes were closed, and the number of lanes entering and leaving Beijing was adjusted to "two in and one out" in the morning and "two out and one out" in the afternoon with the change of traffic volume during the day, and some vehicles were diverted by auxiliary roads. Vehicles leaving Beijing at night are all diverted by auxiliary roads, and the main road keeps two lanes in Beijing.
The section from Zhaoxindian to the city boundary started on May 10 and was completed on August 3 1. All construction projects are arranged from 6: 00 am to 20: 00 pm during the day, with two-way four-lane traffic and normal release at night.
Hebei Duan maintenance
Shi Jing expressway (Hebei section) 1987 was completed, 1992 was partially opened to traffic, and 1994 was completed and opened to traffic. Expressway is the earliest expressway opened to traffic in Hebei Province, the main road from Shijiazhuang, the capital of Hebei Province, to Beijing, and an important part of the Beijing-Zhuhai-expressway, which has played a great role in the past fifteen years. Therefore, it is particularly important to do a good job of maintenance.
I. Improvement and improvement of maintenance technology
The pavement design of Shi Jing expressway (Hebei section) is carried out according to JT0 14-86 Code for Design of Highway Flexible Pavement. Pavement structure: asphalt concrete on the surface is 8cm, 10cm and 12cm, and the base is lime-fly ash macadam and lime soil. The construction method is road mixing at the bottom, rolling molding and asphalt concrete paver at the top.
In the process of pavement maintenance in Beijing-Shijiazhuang-expressway, many new technologies were adopted for different diseases in different periods:
1. The asphalt concrete excavation cover of the west bridge deck of Shahe Bridge adopts polyester fiber asphalt concrete. Compared with ordinary asphalt, the application of polyester fiber asphalt concrete improves the Marshall stability of fiber asphalt concrete, reduces the fluidity of asphalt and increases the water stability, thus improving the service quality and service life of asphalt pavement, but at the same time increasing the cost of fiber.
2. Adopt large area SBS modified asphalt waterproof adhesive layer technology. In order to play a waterproof and bonding role in front of the cover, hot asphalt is sprayed first, and then coarse aggregate with a certain particle size is sprayed, so that the construction machine is convenient to operate, and at the same time, the waterproof asphalt layer is prevented from being damaged due to asphalt bonding during construction. The coating engineering treated by asphalt waterproof technology has good waterproof and bonding effects.
3. Micro-surfacing technology application. Micro-surfacing technology has played an active role in preventing water damage, asphalt pavement aging and prolonging service life. Generally, it can prolong the service life of pavement for 2 ~ 3 years, with high cost performance and convenient construction speed, and can be used in sections with good subgrade.
4, crack repair using new equipment. The processes of crack repair include slotting, dust removal, heating, pouring hot water and ironing, which are not affected by seasons. In recent years, Jingshi Road has been closed to 1.5 million linear meters every year. Timely joint patching effectively curbed the appearance and development of pavement diseases, which is a good preventive pavement maintenance technology.
5. Deep (more than three floors) excavated pits and grooves adopt flexible foundation. When it is necessary to dig and fill the base course in the process of digging and patching, the flexible base course is adopted, which has short curing time and is convenient for small-scale mechanized construction of asphalt pavement.
6. The 6.RSMA thin coating test section is 6 kilometers. Adopt a comprehensive synchronous paver, that is, after spraying the modified emulsified asphalt seal coat, spread it with equipment that can spread 2 ~ 2.5 cm hot mix asphalt.
In addition, the isolation guardrail of Jingshi Road will be repaired; The anti-collision guardrail of the central isolation belt is heightened and reinforced to improve the anti-collision level; The entrance, exit and corner are marked with oscillation signs, and the warning signs have been repaired and improved according to the new regulations. Through daily pavement maintenance, single project maintenance and paving, expressway, Shi Jing has achieved the effects of beautiful road capacity, smooth driving, safety and comfort.
Second, the implementation of preventive maintenance concept
1. Change the usual practice in previous maintenance work, and excavate and repair the pit and groove within 24 hours. In view of the characteristics that road potholes have great influence on driving safety at night and are not convenient for construction, it is required that road potholes should not be dug and repaired overnight, and potholes found on the same day should be treated on the same day. Put the concept of preventive maintenance into practice, that is, when cracks, subsidence, frost boiling and other diseases appear on the pavement and have not yet developed into pits and grooves, deal with the pavement diseases in time to achieve that the pavement is basically free of pits and grooves. In the process of repair work, try to carry out hot repair treatment on asphalt concrete pavement. The process is simple and feasible, which can ensure the smoothness and color uniformity of the road surface. Reasonably optimize the construction of temporary repair works to ensure completion before the rainy season.
2. Usually asphalt concrete pavement is filled in winter, because the temperature of small cracks drops and the shrinkage becomes larger, sealant can be poured to ensure the quality of use. According to the concept of preventive maintenance and the requirements of daily maintenance, diseases are treated in time to ensure the safety and smoothness of roads, so as to achieve the effect of preventive maintenance.
3. Snow removal in winter. Expressway, Shi Jing, put forward the principle of not being affected by snow. In snowy weather, once snow appears on the road surface, snow removal will be started until there is no snow on the road surface. Clear the snow in time to make it stay on the road for the shortest time.
The implementation of the concept of preventive maintenance, while achieving the purpose of prevention, keeps expressway in a good operating state, actively maintains, methodically saves costs.
Three. Discussion on medium repair coverage scheme
After several years of maintenance, the southern part of Wang Du (K179+500-K267+104) was covered in 2006, and the section from Wang Du to Xu Shui (K179+500-K13+365438) was covered.
1, type of asphalt mixture
AC asphalt mixture is a common type of asphalt concrete in China, with continuous gradation, good compactness, good waterproof effect, low noise and wide application. In China, the construction technology is mature, the pavement cost is low, and the construction technology is simple, which needs large-scale mechanical equipment construction enterprises to complete. This project adopts AC- 13C modified asphalt concrete overlay.
2, the proportion of asphalt concrete mixture
At present, there are three kinds of asphalt mixture design methods in China: Marshall asphalt mixture design, GTM asphalt mixture design and superpave asphalt mixture design.
(1) Marshall design method
This is a common design method of asphalt mixture at present, which is simple and easy to operate. However, due to the failure to fully simulate the stress on the pavement, the pavement design index can not meet the requirements of heavy-duty roads, which often leads to early rutting diseases in many expressway after several years of opening to traffic.
(2) GTM is adopted for design.
In 2005-2006, Shi Jing, Xuanda, Shihuang, Shi 'an and other expressway maintenance projects and a number of new highways were designed with GTM. The Xuanda Expressway section designed by GTM has been used for more than five years now, without rutting and water damage, and it is in good condition.
(3) Superpave asphalt mixture design method
This method is based on the volume index parameters of asphalt mixture, such as void ratio, saturation and void ratio of mineral aggregate, to analyze the water stability of asphalt mixture, but it does not consider the strength index of asphalt mixture, which can not guarantee the pavement to have better rutting resistance and crack resistance.
Through the comparison of three design methods, GTM design method is adopted to design overlay asphalt mixture.
3. Selection of asphalt concrete stone for overlay.
Stone materials used by Jingshi Road include basalt, andesite and limestone. It can be seen from the diseases of the paved road section that the net crack and slurry pumping are caused by water damage and heavy vehicles, and wear is the main part, so it is considered to choose high-quality limestone with strong adhesion. In addition to meeting the design requirements, the specifications required to be purchased must be processed by vertical shaft impact fine crusher in the mixing yard, so as to ensure the specifications of the stones and reduce the needle-like content to below 10%.
4. The construction principle of the disease patching scheme before the cover.
The diseases of Jingshi Road are mainly ruts, cracks and pits. Theoretically speaking, the treatment scope, depth and plane scale of these diseases in front of the cover are strong. According to many years' experience in digging and patching, a more practical digging and patching scheme is put forward through the detection of pavement, which relatively narrows the scope of digging and patching compared with previous years. Mainly from the consideration of reducing the disturbance to the surrounding and base, the residual value of the original subgrade and pavement can be fully utilized, and the same force can be borne behind the covering layer to ensure the use function; Consider economic benefits; At the same time, it also takes into account the principles of "foresight, predictability and feasibility". According to the test data such as deflection, rutting, flatness and core sampling analysis, comprehensive analysis is carried out to predict the development of pavement and finally determine the site excavation and repair scheme.
This overlay scheme also puts forward design requirements for asphalt sand belt, kerb, drainage ditch, marking line, movable door in central belt, drainage in bend, entrance and exit of service area, etc. in some sections, so as to maintain and improve the use function of Shi Jing expressway.
The above is the introduction of Zhong Da Consulting on the overhaul and maintenance of expressway, Shi Jing. For more information about expressway, please pay attention to the architectural knowledge column of Zhong Da Consulting.
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