Liunan Expressway (Liunan Expressway), with a total length of 225 kilometers, is opened to traffic in two sections. Liuzhou to Wangling 136 km, opened to traffic on February 8 1998. The safety journey from Wangling to Nanning III is 89 kilometers, and it is open to traffic on 1999 65438+ 10/0/day.
Brief introduction of Binyang-Nanning section of Liunan Expressway in Guangxi
The section from Binyang (Wangling) to Nanning (San 'an) of Liuzhou-Nanning Expressway in Guangxi has a total length of 83.967 kilometers and a total investment of 65.438+83.3 million yuan, which was financed by the Communications Department of Guangxi Zhuang Autonomous Region. This survey and design was jointly completed by CCCC Second Highway Survey and Design Institute Co., Ltd. and Guangxi Zhuang Autonomous Region Traffic Planning Survey and Design Institute, in which the company undertook the section from Nanning (San 'an) to Hengxian (Liujing) (K00. As an excellent project in Guangxi, this project has excellent quality, short construction period, low cost and remarkable social and economic benefits, which embodies the new level of highway survey, design and construction management in China. At the same time, the project won the second prize of excellent design of highway traffic and the third prize of excellent survey in 2006.
Project background
The project is located near the Tropic of Cancer, with beautiful scenery and beautiful mountains and rivers. The total length of the route is 83.976 kilometers, which mainly spans the Naping River, Yongjiang River, qinglong river, Nahe River, Liuchi Reservoir and Gui Xiang Railway. There are 2 extra large bridges, 4 large bridges, 9 medium bridges, 28 separated interchanges, 4 interchanges and 2 service areas. The project started construction on September 1997 and passed the handover acceptance on September 1999. After two years of hard construction, it was completed and opened to traffic one year ahead of schedule. The final accounts of construction drawings save 480 million investment compared with the budgetary estimate, and the social and economic benefits are very remarkable. In September, 200 1 year, the project successfully passed the completion acceptance of the Ministry of Communications, and the project quality was excellent.
Investigation and measurement
The terrain of Binyang (Wangling) to Nanning (San 'an) section of Guangxi Liunan Expressway is complex, with karst, soft soil and expansive soil developed, and there are many sections with good geological conditions. The route corridor is restricted by the existing roads, railways and Yongjiang River, especially the section from Xiaminzhu Village to Liuchi Reservoir. The route corridor is narrow, the terrain is undulating, and the wiring is very difficult, which also brings difficulties to the setting of structures, the layout of drilling holes and the deployment of tools in the exploration process. At the same time, the lush plants and hot and humid weather in the south bring great difficulties to the investigation.
In the process of survey and design, designers went deep into the site to see more, investigate more and study more, made full use of various advanced technologies such as GPS, aerial survey and remote sensing, total station and geological survey, carefully surveyed, and obtained a large number of original data in a short time, which provided basic data for multi-scheme comparison and optimization of route design, greatly improved the quality and efficiency of survey and design, reduced labor intensity, achieved remarkable economic benefits, and reached the advanced level of expressway survey at home and abroad.
Route subgrade
1) adopts the standard of two-way four-lane new expressway in plain and hilly areas, calculates the driving speed 120km/h/h, and compares and optimizes the route and subgrade according to the principles of terrain and geological route selection in the design. Considering the actual terrain, the width of subgrade is 28m and 26m respectively, and its gradual change is completed within the scope of the entrance and exit of interchange. The plane alignment design comprehensively coordinates the topography, landform, engineering geology, hydrology, geology, bridge position, interchange position, local road planning, water conservancy facilities and environmental protection along the line, and optimizes the alignment accordingly, so as to minimize the demolition of buildings and important facilities, save the project cost, occupy less fertile land and maintain the integrity of the original water conservancy system and irrigation and drainage facilities;
2) The alignment of the route design is continuous, and the alignment index is balanced, so as to avoid sudden changes and ensure safe, comfortable and fast driving. Combined with the terrain conditions, the linear elements are used flexibly, and high indexes are not pursued. The longitudinal section design strives to be in harmony with the plane alignment, so as to avoid the top of the convex vertical curve and the bottom of the concave vertical curve from overlapping with the starting and ending points of the plane curve or the inflection point of the reverse curve; Avoid frequent ups and downs of the longitudinal alignment on the straight line, avoid humps, depressions, jumps and other alignments that interrupt the driver's sight, keep the alignment smooth and continuous, and play a good role in visual guidance.
3) For soft soil foundation, according to the characteristics of thin soft soil layer in this area, give full play to the advantages of large-scale mechanical operation, adopt replacement treatment, and take corresponding measures to do waterproof treatment actively and effectively.
4) According to the geological and soil characteristics and landscape requirements, various methods are adopted for slope protection, such as window lining arch, retaining wall and retaining wall combined with anchor rod treatment, which not only ensures the functionality and safety of protection facilities, but also makes the hard landscape diverse and changeable, and increases the greening area of the slope as much as possible. After many tests and full comparison, fly ash and modified additives are used to treat the excavated slope in the expansive soil section. Practice has proved that this method is simple, reliable and economical.
Bridges and culverts
1) The arrangement of small bridges and culverts is based on the principle of not changing the original irrigation and drainage system. Generally, the reinforced concrete slab with a span of 8m is adopted, and the culvert is a reinforced concrete cover plate or a circular pipe culvert, with uniform standards, which greatly facilitates the construction and later maintenance.
2) In order to facilitate the construction, reduce the cost and ensure the quality, large and medium-sized bridges mainly adopt the continuous scheme of hollow beams with a span of 20m and simply supported decks;
3) By further optimizing the design scheme of the main bridge of Liujiang Yujiang Bridge, the 220m half-through steel tube arch is adopted in the construction drawing design. The bridge has a beautiful shape, and the main bridge is bright gray in color, which is both personalized and unobtrusive, and aesthetically highlights the integration with the beautiful scenery on both sides of the Yujiang River. In 2002, the bridge won the third prize of excellent design from the Ministry of Communications.
Hutong junction
In the design of interchange, the aesthetic requirements for lines and overpass bridges are particularly emphasized. The overpass bridge, especially the curved slope inclined bridge in the super-high section of interchange ramp, adopts reinforced concrete continuous box girder or box continuous rigid frame, which is matched with thin-walled pier or single-column pier. The bridge has the advantages of light structure, beautiful appearance, low investment and good use effect. In addition, on the basis of full demonstration, according to the actual traffic volume in this area, by reasonably adjusting the horizontal and vertical linear indexes of the interchange ramp, the scale of the interchange area can be reduced as much as possible, which not only saves investment, but also serves the local economic development.
Landscape and environmental protection
1) The route direction should be coordinated with the topography, environment and landscape, so as to reduce land occupation and demolition and protect the environment and natural landscape in the road area to the maximum extent. For the stone forests and trees on the roadside, the principle of combining avoidance with landscape guidance is adopted to make the road integrate into the natural landscape (Figure 1). For the local unavoidable high-filling and deep-digging road slopes, the measures of combining engineering protection with biological protection are adopted to increase the green area as much as possible, so that drivers and passengers feel safe and comfortable and the environment is beautiful;
2) Keep the existing water conservancy measures and runoff system to the maximum extent, do a good job in the reconstruction project of irrigation and drainage system, occupy less farmland, reduce soil erosion, and promptly remove topsoil or cultivated soil and pile it in the designated place in order to restore cultivated land;
3) The choice of structure type should not only meet the requirements of convenient use, convenient construction and reasonable cost, but also strive to be integrated with the natural landscape and become a part of the landscape;
4) Set up separated overpasses, passages and culverts reasonably, so as not to bring inconvenience to people's production and life due to expressway construction;
5) Do a good job in highway slope greening, combine the setting of borrow yard with the reconstruction and restoration of cultivated land and farmland, and do a good job in greening. According to the different topography along the line, plant all kinds of shrubs, trees and flowers to beautify the environment, reduce dust and isolate noise sources;
6) Do a good job in construction organization design to minimize the impact of construction on the environment. After the project is completed, do a good job of site cleaning and leveling, and trim the road capacity.
The above is the introduction of Yimao Zhong Da Consulting to Liunan Expressway. For more information about expressways, please pay attention to the architectural knowledge column of Zhong Da Consulting.
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