In the last issue of the content [road design and road lofting], the background received a lot of friends messages: such dry goods articles come to several waves! Well, this issue of dry goods article continues to go up!!!
Road cross-section and road ultra-high, widening, slope, Engineering Star 5.0 operation method analysis!
01
Standard cross-section
A standard cross-section is a section perpendicular to the direction of the road's centerline, as shown in the figure.
The composition of highway and urban road cross-section is different, the main components of highway cross-section are: roadway (road surface), road shoulder, side ditch, slope, green belt, separation belt, retaining wall, etc.; urban road cross-section composition is: roadway (road), sidewalk, curb stone, green belt, separation belt and so on. In the sections of high embankments and deep grabens, including retaining walls, etc., symmetrical and asymmetrical distribution forms can be made according to the cross-section of the terrain and terrain standard.
Cross-sectional surveys, measured elevations, what does the actual role of the generation play? The simplest understanding: calculating the quantity of earthwork.
Standard cross-sectional data entry:
Enter the standard cross-sectional interface, click "Add", enter "name (such as roadway, sidewalk, etc.)", "width", "slope" (from the midline of the road, the uphill of the plate is positive, the downhill is negative, the slope value is the ratio of the height difference between the two ends of the plate and the width of the plate, the slope ratio is 1:2 is 1/2=50%, enter 50)", Daoya (and the previous plate height difference, positive is high, negative is short), the left section is normal input, the right section clicks on the symmetry to copy the properties of the left section, click "View" to view the shape of the current section.
02
Ultra-high concept and operation
In the highway curve, in order to balance the centrifugal force generated by the car when driving on the corner, (lateral force or centrifugal force will produce slip or overturn), the route is designed to be a one-way slope with high outside bend and low inside bend to eliminate the centrifugal force of the car.
Ultra-high is adjusted according to the ultra-high horizontal slope, generally 1.5%-6%. You can refer to the Highway Route Design Code or the Urban Road Design Code.
Obvious externally measured ultra-high real shots
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Ultra-high data entry:
First select the plate that needs to be super high, such as the central partition belt on the left side needs to be super high, click "Add", enter "Mileage, Slope", as shown in the figure (assuming that the slope of the central partition in the standard cross-section is 0):
(1) Mileage 0 to 20: the slope is 0, that is, the slope of the central divider under the standard cross-section;
(2) Mileage 20 to 40: slope changes linearly from 0 to 4%;
(3) Mileage 40 to 60: slope changes linearly from 4% to 0;
(4) After mileage 60: the slope is 0, that is, the slope of the central divider under the standard cross-section
The whole is formed into a closure.
03
Widening concept and operation
Broadening the concept of understanding:
When the car is driving on the curve, the driving path of each wheel is different, and the rear wheel on the inside of the curve has the smallest driving radius, while the front wheel on the outside of the curve has the largest driving radius. In order to ensure the safety of the car when turning (not encroaching on adjacent lanes), all curved sections with a radius of less than 250m need to be widened.
1, according to the trajectory of the vehicle, the curve should be wider than the straight line, and because of the length of the body, the position occupied on the curve is wider than the straight line, so it should be widened on the curve, but when the corner radius > = 250 meters, it can not be widened.
2. Unless the outer side is not widened because the natural conditions are not available, the widening of road curves is generally added to the inside.
See Technical Standards for Highway Engineering (JTG B01-2003) and Highway Route Design Code (JTG D20-2006).
Obvious internal test widening real shot
Widened data entry:
First select the plate that needs to be widened, such as the central partition on the left side of the plate needs to be widened, click "Add", enter "Mileage, Width", as shown in the figure:
(1) Mileage 0 to 80: the width is 4, that is, the width of the central divider under the standard cross-section;
(2) Mileage 80 to 100: width changes linearly from 4 to 5;
(3) Mileage 100 to 120: width changes linearly from 5 to 7;
(4) Mileage 120 to 140: width changes linearly from 7 to 4;
(5) After mileage 140: the width is 4, that is, the width of the central divider under the standard cross-section;
The whole is formed into a closure, as shown in the figure on the right below.
04
Slope concept and operation
The slope is to ensure the stability of the roadbed, and the slope is made on both sides of the roadbed with a certain slope.
Slope Concept Understanding:
Left digging: it is understood to dig the pavement low, that is, the left slope is higher than the pavement;
Right digging: the right side slope is higher than the road surface;
Left filling: it is understood to fill in the road surface high, that is, the left slope is lower than the road surface;
Right fill: The right side slope is lower than the road surface.
Slope data entry:
First select the "Slope Type" → click "Add" → enter the "Slope Point Mileage" → select the "Gradient Mode (Mutation or Gradient)" → "Add" → Enter "Name, Width, Slope" → click "Save" when the input is complete, or you can continue to click "Add".