Question

produce a report (300 words min) which identifies the requirements for drainage within the railway infrastructure and the methods of achieving adequate drainage. use a section of track as an example and illustrate your report with photographs and drawings as appropriate. explain the common failure modes associated with track drainage.

Answer 1

DESIGN PROCEDURE FOR DRAINAGE:

• ​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​It is to be designed to capture water flows and calculate in accordance with this part
• Safety Transfer flows to an approved point of discharge into the tack drainage system without approval.

Formation Drainage:

• Primary Drainage of track is through the ballast could fed into the sides of the track by the slope on the formation.
• Side Drains Should be provided along the track in cuttings and zero fill locations, where the cess level is not above ground level.
• On embarkments where erosion is critical and incutting, longitudinal drains are tobe constructed in the cess.
• To avoid the cess drainage being subjected to excessive silting, tops of cutting shall also be drianed with logitudinal drains from the edge of the cutting.
• On the large embankments it is necessary to construct drains of earthware.
• Where surface drains cannot provide adequate drainage and sub surface drains should be installed

METHODS FOR ADEQUATE DRAINAGE:-

1. Surface Drainage
2. Sub-Surface Drainage

Surface Drainage:

• It removes surface water by development of the slope of the land utilizing systems of drains to carry awat surplus water
• The surface water which is occured due to rain etc., should be drained properly by designing well planned and effective surface.
• For bank and formation good quality so having well graded particles and high internal friction should be used.
• The soil should not be shrink or swell with variation of moisture content.
• The surface water is first collected in well designed drains and cross drains which is diposed to near natural water resources.

SUB-SURFACE DRAINAGE:

• In this process to remove excess water away from soil.
• Fluctuations in movement of capillary water
• Rising of ground water tube.
• Seepage water from adjacent areas.

The Common Failures Associated with track drainage and failure modes of fine subgrade soils, exacerbated by the presence of water as describe as follows

1. SUBGRADE PROGRESSIVE SHEAR FAILURE:

IT develops at the subgrade surface as the soil is sheared and remoulded due to cyclic over- stressing. In this type of failure the surface of the subgrade gradually squeezes outward and upward following the path of least resistance.

1. EXCESSIVE SUBGRADE PLASTIC DEFORMATION:

  The problem of an excesive rate of settlement through plastic deformation usally results in ballast pocket. The ballast pocket is formed vertical component of shear deformation caused by progressive compaction of subgrade layer resulting from repeated loading.