- Terrain reconnaissance – what we are dealing with
- Grading and ditching
- Water channel device
- How to make an embankment and how to protect it from erosion
- We refine the check-in – materials and equipment
It often happens that the only convenient entrance to the site is blocked by a drainage or drainage ditch. This creates additional difficulties in the construction of the driveway, makes it difficult to work on landscape design and paving. Today we will share the main tricks of the device for driving through a ditch..
Terrain reconnaissance – what we are dealing with
A ditch next to the site, whether it be a drainage trench or a natural stream, is always part of a more complex system responsible for the hydrogeological balance of waters over a fairly large area. Disruption of this system almost always and rather quickly leads to flooding, soaking of the soil, including its support layers. It is in your interests to carry out such structures competently and in accordance with technical regulations..
It is necessary to transfer to the sketch the profile of the ditch on a scale, reflecting the gentle slopes and the relief of the adjacent territory. The width of the ditch is determined by the two highest points, from which the descent begins, and the difference between the line connecting these points and the bottom of the ditch is conventionally taken as the height. Make no mistake in your calculations: usually under one or both banks there are spoil heaps, which over the years in the open air have turned into gentle shafts. You also need to push off from the plane of the adjacent territory, without taking into account the “influx” in front of and behind the ditch.
If the stream is natural, one bank may be lower than the other, while each remains in its own plane. In this situation, it will be necessary to artificially raise the lower level in bulk. Note that the methods described by us are suitable for the construction of passages through a ditch up to 2.5 meters deep and up to 5-6 meters wide; larger ditches require an individual and professional approach.
Grading and ditching
The width of the passage can be up to four meters (for trucks), while one meter on each side is left as protective zones that do not bear the operational load. In general, the width of the section to be planned is 6 meters, which correlates well with the standard length of pipes used for drainage..
The first planning task is to give the ditch a constant profile across the entire width of the driveway, eliminating bends and narrowings. The trench at the driveway should take the shape of an inverted trapezoid with a flat bottom, from 40 cm to a meter wide, depending on the diameter of the pipe used. To prevent the pipe from being sucked into the ground, the bottom is deepened by a rectangular pit 250 mm deep for an incompressible bedding device.
Expanding the ditch – cutting the walls – is almost always necessary, the soil from the dump is used to level the adjacent territory. If the difference between the levels of the banks is up to 20-30 cm, leveling can only be carried out with excavated soil. If more, the upper layer of the embankment should consist of quartzite crushed stone of fraction 30–35 mm and be at least 1 cm thick. It is better to dump the removed chernozem separately and keep it until the beginning of landscaping.
Water channel device
The protective zones on the sides of the driveway need to be expanded by making half-meter cuts into the walls of the ditch. They should be dug up to the highest point of the coast along the very edge of the embankment, and if the ditch is more than 5 meters wide – with an additional 0.5 meter approach to flat areas.
The pit at the bottom is filled with road crushed stone of fraction up to 50 mm, it is also partially filled in the gaps to give the inclined trenches a constant depth of at least 60 cm.
A flow channel is laid across the passage along its entire width, the lower edge of which is at the same level with the bottom of the ditch or below it. Typically, the channel is made of steel pipe with a cross section of 300 to 500 mm, preferably lined. The outside of the pipe must be either primed and painted or covered with bitumen mastic. Due to their small cross-section, the ends of steel pipes must be equipped with a removable welded grating with a cell of no more than 150 mm to protect against clogging.
The wider the channel, the lower the likelihood of its siltation; with a clearance diameter of 600 mm, such a pipe can even be considered serviced. Large-section channels are best made of reinforced concrete rings with a quarter-lock. With the same success, it is possible to lay concrete U-shaped boxes (inverted trays), which are used in the construction of heating mains.
Road drainage pipes, corrugated with stiffening ribs, or the most durable HDPE for main pipelines are also suitable. Remember that the width of the channel used determines the geometry of the profile of the ditch at the planning stage: the bottom of the “trapezoid” should be 30-40 cm wider than the pipe. Note also that even with a significant slope of the ditch, the flow pipe is laid strictly horizontally, and the difference in levels is compensated by the increased diameter.
How to make an embankment and how to protect it from erosion
The task of the “gouges” at the edges of the protection zones is to protect the roadway embankment from being squeezed out. As stops for the embankment, sides are used, lined with stone, silicate bricks or cast with reinforced concrete with a slab thickness of 70-80 mm.
The formwork is constructed in such a way that the channel edge protrudes 100 mm beyond it on each side. It is often easier to fill the bottom of the ditch with a sand and gravel mixture to level and hide the pipe, and then carry out the construction of the sides.
The board should protrude 150-200 mm above the highest point (banks). The top of the sides is the starting point for the construction of the road surface and the filling cake, as a result, the surface should be 50–100 mm higher than the adjacent territory. After installing the sides, the trench inside must be filled with rubble to a level 250 mm below the upper edges.
Further, with an indent of 80 cm inward from the sides, two curb stones up to 100 mm wide are cast (stacked). To create a chamfer on the edge, the formwork can be filled with glazing bead, along which it is quite easy to level the mixture.
The curb separates the flowerbed on the side of the road, so that the formed space can be immediately filled to the top with black soil. It is optimal if the length of the curbs corresponds to the length of the sides, that is, two small trenches were previously dug along the entire length of the passage. In this case, it is better to close the ends of the flower beds at an acute angle for more convenient entry with a turn.
We refine the check-in – materials and equipment
A rectangular recess with curbs on the sides and a total depth of 250 mm was obtained for the device of the roadway. Of these, 100 mm are covered with finer gravel, which is well rammed and spilled several times with water. In this case, the lower layers of the embankment also sag, so periodically quartzite must be added until shrinkage disappears. In the remaining 150 mm, a layer of asphalt concrete or paving slabs can be laid on a 20 mm backfill from granite screening.
The resulting passage is completely protected from subsidence, accordingly, it can be paved with anything at all, or simply left in bulk. It is much more important to correctly arrange the flower beds and the adjacent parts of the ditch. Flowers or lawn grass can be planted along the driveway. The adjacent sections of the ditch, 2.5-3 meters each, need strengthening of the slopes.
They should be planted with moisture-loving plants, mainly shrubs with a dense branched root system: irises, willow or rose hips, you can also sow creeping grasses or create a hedge. Greening these places will not only protect the slopes from erosion, but also visually smooth the relief and get rid of unpleasant dampness.