Housing contributions
Shandong Xunchi Traffic Engineering Co., Ltd
Abstract: Taking the comprehensive utilization of land under the influence of land acquisition conditions and local development needs of an interchange in an urban area as an example, this paper introduces the ideas and methods of comprehensive land utilization of the interchange, and discusses the comprehensive utilization method of land resources of the interchange.
Keywords: highways; interchanges; Land resources; Comprehensive utilization;
About author:FANG Jiangong (1976—), male, from Linyi, Shandong, research direction is highway bridges.
introduction
The construction of expressways and urban road interchanges has brought vitality and impetus to the development of urban areas and towns, which not only helps to alleviate the traffic pressure of cities, but also solves the cross-regional long-distance traffic needs of urban residents, and is also conducive to improving the image of cities and driving the development of local economy [1]. At this stage, the constraints of urban development are becoming more and more obvious, especially in important areas such as urban areas and urban areas. The construction of the interchange will inevitably occupy a large area of land resources, and the quadrant position of the interchange should be scientifically and reasonably laid out under the requirements of various normative indicators. Select various linear indicators that meet the specifications, try to make full use of the land resources occupied, save floor space, and reserve space for the development of the surrounding city.
1 Project Overview
The Longshan Interchange is a provincial highway and a first-class highway, running north-south with a pavement width of 32 m. According to the topography, features and predicted traffic volume of the interchange area, the A-B double-horn hub interchange of the main line is adopted. The toll station is located in the northwest quadrant where the main line intersects with the intersection, and the toll station adopts 3 in and 7 out, and 1 in and 2 out ETC lanes.
2 Design Criteria
(1) The minimum design speed of the ramp is 40 km/h. (2) The width of the ramp subgrade is 10.5 m for one-way dual carriageway and 19.5 m for two-way dual carriageway. (3) The minimum radius of the ramp is 60 m, and the length of the roundabout is ≮50 m. (4) The maximum longitudinal slope is 4%, the minimum radius of the convex vertical curve is 900 m, and the minimum radius of the concave vertical curve is 900 m. (5) The design speed of the main line is 120 km/h, and the single-lane acceleration lane adopts parallel type, with a minimum length of 230 m and a gradual section of 90 m. The deceleration lane adopts a direct type, with a minimum length of 145 m for a single lane and a length of 100 m for a gradual section.
3 Constraints
In order to make comprehensive use of the land resources in the Longshan Interchange Circle and avoid the demolition of the office building of a high-speed rail project department and the houses occupied by three auxiliary roads on both sides of the provincial road, the alignment of the F ramp was adjusted, and the F ramp bridge and the F ramp retaining wall were added for slope closure treatment; Adjust the position of the auxiliary road on the north side to avoid the difficulty of requisition and demolition, and the auxiliary road will be changed from the original design A ramp AK0+750.0 channel underpass to cross the F ramp bridge, and at the same time adjust the original A ramp AK0+750.0 channel size.
In order to make full use of the triangle area between the G ramp, the A ramp and the provincial highway to be crossed, the shoulder retaining wall on the left side of the A ramp and the left side of the G ramp was added, and the auxiliary road was compressed to the vicinity of the A ramp retaining wall. At the same time, considering the comprehensive use of land, after the cancellation of the toll station office area, the toll plaza fill height is higher, and it is necessary to add an emergency passage under the toll to facilitate the toll collectors to enter and exit the toll station. The original design of the traffic police ETC room in the toll station entrance side, is not conducive to the traffic police work demand, the housing construction position needs to be adjusted, adjusted to the toll station exit, the toll station exit side fill height is higher, and the retaining wall has been completed, need to add a filling area for treatment.
4 Comprehensive land use plan
(1) Cancel the office area of the original A ramp toll station, make comprehensive use of the existing buildings nearby, and add one emergency passage under the A ramp. (2) In order to add a special room for traffic police ETC near the vehicle exit side of the A ramp toll plaza, it is necessary to add a filling area on the west side of the constructed retaining wall on the left side of the A ramp toll plaza area. The filling area was filled with a 30 cm C30 concrete baffle and backfilled with foam lightweight soil. The drainage ditch on the outside of the retaining wall of the original A ramp was changed to the outside of the baffle, and the pavement in the filling area was in the form of cement concrete pavement, and the pavement structure was 26 cm C30 cement concrete + 20 cm cement stabilized gravel. (3) In order to avoid the demolition of the office building of a high-speed rail project department, the two-story building on the north side of the provincial highway, the structure on the north side of the provincial highway and reduce the occupied area of the auxiliary road, adjust the flat and longitudinal shape of the F ramp, and partially compress the hard shoulder on the right side of the starting point area of the F ramp, and add one cast-in-place F ramp bridge (span diameter 12m+16m+12m) in the office building of the high-speed rail project department. (4) Cantilever shoulder retaining walls are added in three places on both sides of the F ramp to carry out slope closing treatment, and the auxiliary road on the north side is changed from the original design A ramp passage to pass through the F ramp bridge. At the same time, the original 1~10 m prestressed concrete hollow slab steam pass of ramp A was changed to a 1~6 m box pass; Optimize and adjust the alignment of the auxiliary road on the north side, add a cantilevered shoulder retaining wall on the left side of ramp A and the left side of ramp G to close the slope and compress the auxiliary road to the vicinity of ramp retaining wall A. (4) In order to avoid the expropriation and demolition of the two-storey building on the south side of the provincial road, the hard shoulder on the right side of the starting point of the A ramp was partially compressed, and the alignment of the auxiliary road on the south side was optimized and adjusted. (5) Foam lightweight soil has the characteristics of lightness, adjustable gravity and strength, self-flowing, uprightness, easy excavation and construction convenience. For the comprehensive utilization of the triangular area that has been requisitioned at the side of the interchange toll station, considering the factors such as the shoulder retaining wall that has been set on the side of the toll station, and the retaining wall is high, and the compaction of the triangular area is difficult, the concrete baffle plate is set and the foam lightweight soil is poured to backfill the treatment. See Table 1 and Table 2.
Table 1 Technical indicators of foam lightweight soil Download the original figure
Table 2 Measured items of foam lightweight soil subgrade Download the original map
Note: Q1 and Q2 in the table are the specified or design values for the compressive strength of the embankment and roadbed, respectively [2].
5 Conclusion
For the land resources in the interchange area, the main influencing factors are land acquisition and demolition, the development of local enterprise plants, the demands of government functional departments, and the long-term land planning needs, etc., and it is necessary to comprehensively consider a variety of factors in the interchange area. Under the condition of meeting the requirements of the specification, the difficulties can be effectively avoided and the purpose of comprehensive utilization of land resources in the interchange area can be achieved by using methods such as local optimization of alignment, addition of roadside retaining walls, adjustment of counseling positions, backfilling of slopes with foam lightweight filler, and addition of bridges to reserve development corridors. The interchange has been opened to traffic for nearly 3 years, and the interchange service is running well, and the surrounding environment is suitable.
bibliography
[1] Qin Zhaoliu. Analysis and design discussion of urban road interchange characteristics[J].Protection Engineering,2018(9).38-58.)
[2] Ministry of Housing and Urban-Rural Development of the People's Republic of China. Technical specification for bubble mixed light soil filling engineering:CJJ/T 177—2012[S].Beijing:China Architecture & Building Press,2012.
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