Subway; Clearance standard; Clearance calculation method
The Gauge of Urban Rail Transit stipulates the section shape and gauge size of rail transit vehicles and tunnels, as well as the gauge size of overhead and ground buildings, and also stipulates the installation position and reserved space of equipment, which is one of the basic guarantees for the safe transportation of urban rail transit and the basis for the design of urban rail transit [1]. Compared with overhead vehicles and ground vehicles, vehicles in tunnels run underground in cities. Due to the characteristics of small tunnel section diameter, compact equipment installation space, small track curve radius and high passenger comfort, higher requirements are put forward for vehicle clearance and equipment clearance of urban rail transit.
Urban rail transit clearance not only restricts the external dimensions of vehicles, but also relates to the internal contours of various buildings such as tunnels, which has a great influence on the construction scale and input-output of rail transit system. In order to ensure the unification, serialization and standardization of urban rail transit gauge, Professor Shen Peide organized relevant experts and presided over the compilation of the national industry standard for metro gauge [1] to meet the requirements of safety, applicability, economy and technological advancement.
Determination of calculation parameters of vehicle contour line and vehicle clearance for 1A car
At present, there are many A-type cars used in China's subway. Shanghai Metro 1 Line takes the lead in using Type A cars, followed by Guangzhou Metro 1 Line. Shenzhen and Nanjing rail transit lines have decided to use Type A vehicles. As Type A vehicles on Shanghai Metro and Guangzhou Metro have been in operation for many years, the calculation of vehicle contour lines is based on Shanghai Metro and Guangzhou Metro, determined with reference to Shenzhen Metro and Nanjing Metro, and the arrangement of car body side lights is considered (as shown in figure 1 and table 1). In addition, the parameters for calculating the vehicle clearance of Type A vehicles are determined after careful consideration on the premise that the above vehicles can be covered.
Figure 1A car (3m wide) Calculate the vehicle contour line.
2 Urban rail transit vehicle clearance calculation
In the past, the calculation of vehicle clearance adopted the international standard U IC 505 issued by the League of Nations. This standard is an international standard for cross-border railway transportation, and its vehicle clearance calculation is based on the vehicle reference contour line, on which the dynamic envelope is calculated, and then the equipment clearance is calculated. The standard considers fewer factors in the calculation of vehicle clearance, and cannot fully meet the development requirements of urban rail transit [2]. Therefore, Germany promulgated the Bostrab national standard for urban rail transit in 1997. In this standard, the vehicle clearance is directly calculated from the contour line of the vehicle manufacturing, and all possible deviations from the sleeper to the top of the vehicle are considered. Under the premise of normal maintenance of lines and vehicles, there is no need to consider the safe distance. The calculation method of German Bostrab standard is more suitable for rail transit than U IC international standard, and more suitable for determining the vehicle clearance of urban rail transit [2].
Based on the above two standards and references [3 and 4], the gauge calculation method suitable for the actual situation of rail transit construction and vehicle operation in China is determined.
2. 1 Calculation principle of vehicle clearance
1) clearance is the basis for determining the clearance of structures around the running track and the mutual position of pipeline and equipment installation. It is a technical regulation that professionals abide by and should be economical, reasonable, safe and reliable.
2) The clearance shall be determined by analysis and calculation based on the overall factors such as vehicle dimensions and technical parameters, track characteristics, power receiving mode, construction method and equipment installation.
3) The calculation of vehicle clearance is based on the lines of concrete monolithic ballast bed and crushed stone ballast bed on a straight line. According to the different operating environment in tunnel and ground, it can be divided into two basic types: vehicle clearance in tunnel and overhead line (including ground line).
4) The curve segment is different from the above two cases, and the additional factor is to consider widening and heightening within the equipment clearance.
5) The calculation factor (offset) of vehicle clearance is ..., and the random factor is synthesized by mean square value according to Gaussian probability distribution. Add the above two categories to form the dynamic offset of the vehicle.
8) The calculation of vehicle clearance offset is divided into three parts: car body, bogie and pantograph (three-rail current collector).
9) Once the vehicle clearance is established, it is an important part of the clearance standard. Whether the vehicle is running safely must be calculated according to the basic provisions of this calculation method, and whether the dynamic envelope of the vehicle exceeds the vehicle clearance shall prevail.
10) The vehicle contour calculation and calculation parameters involved in this calculation method are only used when making gauge, and are not mandatory for vehicle specifications and parameters. The actually manufactured vehicles should be checked according to the actual parameters according to the basic provisions of this calculation to see if they meet the vehicle clearance.
2.2 Calculation elements of vehicle clearance
1) Vehicle manufacturing error;
2) Vehicle maintenance limit;
3) The bogie wheelset is in the most unfavorable running position on the track;
4) Lateral vibration of the wheelset relative to the frame;
5) Lateral displacement of bogie frame relative to car body;
6) Deflection difference and vertical displacement of empty and loaded vehicles;
7) Geometric deviation of track line (including maintenance limit);
8) One suspension roll displacement;
9) secondary suspension roller displacement;
10) Deflection caused by vehicle manufacturing, asymmetric load and uneven track level.
2.3 Calculation methods of vehicle clearance, equipment clearance and building clearance
Based on the determined coordinates of the control points used to calculate the vehicle contour line, consider