What Are The Methods Of Railway Subgrade Slope Protection？
Feb 23, 2022| What are the methods of railway subgrade slope protection？
1、 Slope protection includes
1. Plant protection: planting grass, spreading turf and planting trees.
2. Engineering protection (mineral material protection): frame protection, cover, protective wall, dry rubble slope protection, mortar rubble slope protection, mortar precast block slope protection, anchor wire mesh shotcrete and shotcrete slope protection.
2、 Applicable conditions of various protective works
（1） Plant protection
1. Grass planting protection: it is applicable to embankment and cutting slopes with stable slope, slight rain erosion on the slope and easy to grow grass. Grass species with developed roots, low leaves and stems, long-term growth and suitable for local soil and climate conditions shall be selected and planted in the topsoil layer of 40cm (topsoil thickness ≥ 20cm when there is no mature soil). Sowing methods include sowing, spraying and row sowing. At present, two new methods are wet spray seeding technology and guest soil spray seeding technology.
2. Turfing: suitable for soil slopes requiring rapid greening. There are four paving forms of turf slope protection: tiling, stacking, square format and egg (chip) stone format.
3. Shrub planting: it is used in combination with grass planting and turf paving to form a good protective layer on the slope, which is suitable for soil slope and expansive soil slope, but it is not suitable for slope with saline soil often soaked and often dry and silty soil slope. Shrubs should be planted on the slope with a ratio of 1:1.5 or slower, or on the river beach on the Bank of the embankment, so as to reduce the flow velocity and promote sediment deposition.
（2） Engineering protection
1. Frame protection is applicable to soil or weathered rock slopes. Concrete, mortar rubble (block) stone, pebble (gravel) stone, etc. can be used as the frame for frame protection. Plant protection or other auxiliary protection measures should be used in the frame.
2. The cover includes plastering, hammering, shotcreting, shotcrete and other protective forms.
(1) Plastering protection is applicable to the excavation slope of easily weathered soft rock. The rock surface is relatively complete without peeling.
(2) Hammering protection is applicable to soil slopes and weathered rock slopes vulnerable to rain erosion.
(3) Shotcrete and shotcrete protection are applicable to rock excavation slopes with easily weathered slopes, developed fissures and joints and uneven slopes.
3. The face protection wall is used to close all kinds of soft rock strata, relatively broken excavation slopes and soil slopes whose slopes are vulnerable to erosion. The excavation slope protected by protective wall should not be steeper than 1:0.5, and should meet the requirements of extreme stable slope. The face protection wall is divided into solid type, window hole type, arch type and other types, which shall be reasonably selected according to the geological conditions of the slope.
4. Stone slope protection
(1) Dry rubble slope protection is applicable to the slope protection of soil slope vulnerable to water erosion, soft rock slope seriously peeled off, periodic immersion and river bank or reservoir bank slope slightly scoured by water flow (velocity less than 2-4m / s).
(2) Mortar rubble (Pebble) slope protection is applicable to the slope with large velocity (3 ~ 6m / s), strong wave action and impact of running water and floating objects. For soil slopes that are excessively wet or severely damaged by freezing, drainage measures shall be taken before paving.
5. Mortar precast block protection is applicable to areas lacking stone materials. The concrete strength of precast blocks shall not be lower than C15 and C20 in severe cold areas.
6. Anchor wire mesh shotcrete or shotcrete slope protection is applicable to the discontinuous stratum with hard rock or layered structure whose straight face is cataclastic structure, as well as the excavation slope where the slope rock is separated from the bedrock and may slide down. The construction is simple and the effect is good.
（3） Geotextile protection
1。 Hanging net slope protection is suitable for rock slopes with serious weathering and debris. The geonet hung along the slope can intercept the falling rocks and guide them into the side ditch or other controllable areas. It is difficult to use when the diameter of rockfall is large and the slope inclination is greater than 400.
2. Geotextile composite vegetation protection slope integrates the advantages of geotextile and vegetation protection. Its typical form is three-dimensional soil net (MAT) grass protection. It is mainly applicable to soil slopes with a slope gradient of less than 1:1 and a slope height of less than 3m.
3. Other geotextile protections include lawn vegetation belt, bolt hanging high-strength plastic mesh shotcrete (shotcrete) suitable for broken or easily weathered rock cutting slope, and slope protection with geotextile as inverted filter.
