2. The establishment of topographic survey and construction control network.
3, route construction lofting
1) Subgrade slope lofting
2) Layout of excavation section
3) Pay-off of fill section
4) lofting the structure.
5) Side ditches and ancillary facilities
Construction method of earthwork subgrade: (1) general road filling 1. Before subgrade filling, measure and set out according to the design requirements, determine the position of the center line and sideline, and pull the wires according to the layer thickness requirements. 2. Clean up the cultivated soil on the surface of the line range, dry it, and then roll it with a light roller to meet the design requirements. 3. Select the test section in the soft foundation treatment section. The location of the test section should be selected in the representative section of K7+330~K7+450. The materials and machines used in the test should be the same as those used in the future construction of the whole line, so as to determine the type of compaction equipment, the best combination mode, the best water content, the compaction times, the speed, the technology and the control of the filling thickness under different fillers and different compaction requirements, make construction records in the middle, and strengthen the detection of relevant indicators. Write the test report and construction summary in time after completion, and put forward the best construction scheme that meets the requirements of JTJ033-95 Technical Specification for Highway Subgrade Construction. When there are defects in subgrade design, put forward design change opinions and report them to the supervision engineer for approval as the basis for subgrade construction. 4. Roadbed filling width and height Roadbed filling adopts layered parallel paving, and the loose paving thickness of each layer is determined according to the field compaction test. The paving width of each layer of filler exceeds the design width of 30cm on both sides of the embankment, and the width of both sides of the soft foundation construction section is 50cm according to the design width, so as to ensure sufficient compactness of the embankment edge after subgrade settlement and subgrade slope trimming. The average length of the longitudinal section is about 250 meters, and the construction method is mainly mechanical construction, supplemented by labor. The loose laying thickness of each layer shall not exceed 30cm. The particle size of filler should be controlled within 15cm (the crushing of subgrade filler should be carried out at the exit). After each layer is paved, it shall be leveled first, and then rolled to ensure the flatness of each layer, and 2~4% cross slope shall be made to facilitate drainage. 1, subgrade construction lofting is the same as general, but there is a principle that "the width cannot be narrow". When placing the side piles of each layer of fill, the half width of subgrade should be 30 ~ 50 cm wider than the designed half width. The purpose is to ensure the compaction quality of the slope!
2. Superelevation and widening should be adjusted below the road surface! Otherwise, the pavement thickness is either insufficient or too thick. Affect the cost. (Subgrade does not adjust the superelevation of railway subgrade)
3. The specific implementation shall refer to this specification. The straight line is 50- 100 m, the curve is 20 m, and the point is 40 m.
Preparation before construction
1. Preparation contents: organizational preparation, material preparation and technical preparation.
Second, the general situation of construction
1, centerline recovery and calibration
To restore the center line of the route, it is necessary to check it according to the route plan, several turning points list of straight lines and curves, pile protection records, etc. Post layout design.
2. Check and add leveling points
3, cross-sectional inspection and supplementary measurement
4, the reserved bridge position
5, the measurement in the construction, mainly check whether digging, filling meets the design requirements.
6, other matters in the measurement.
Third, the subgrade lofting
1, content:
A, calibrating the filling and excavation height of each midpoint of the road centerline;
B, determining the direction of the cross section,
C, according to the design drawings, determine the positions of various points on the cross section on the ground, such as the center point of subgrade, the edge point, the toe of embankment slope, the top of cutting slope, etc.
D, slope template prevention: mark the position of the slope according to the designed subgrade slope;
E, move the pile and move the point.
2, subgrade slope lofting
Method:
The graphic method directly measures the distance between the shoulder, the toe of the slope and the center line of the drainage ditch on the ground according to the cross-sectional drawing, and determines the sideline piles.
If there is no cross-sectional drawing, the calculation method can only be used to fill and excavate the side slope of subgrade on the ground by calculation method.
On the plane, the distance from the toe of embankment slope to the middle pile should be prevented.
L=b / 2+mH
When the lateral slope of the side piles laid on the slope is large, the influence of the lateral slope should be considered in the calculation.
The distance from the uphill foot to the pile is l = b/2+m (h-h) l = b/2+m (h+h).
In the construction, the transverse slope of the ground can be measured first and then calculated according to the formula.