Railway Embankment in Acton

Utilising Leca® Lightweight Expanded Clay Aggregate for Railway Development



In highway and railway structures Leca® Lightweight Expanded Clay Aggregate is commonly used as a light fill material to reduce subgrade settlement and to improve stability of structure and the surrounding area. It serves as a similar purpose when used in pedestrian and bicycle throughways, rail yards and different platform and embankment structures.

In the reconstruction of highways and railways Leca® Lightweight Expanded Clay Aggregate can be applied to repair settlement defects, to increase levelling and to improve bearing capacity. In addition, with the help of Leca® Lightweight Expanded Clay Aggregate road and rail embankments that require widening can be constructed with minimal effect due to increased loading to the existing structure.

WHEN PROPERLY PLACED AND COMPACTED THE MAXIMUM EXPECTED LONG TERM COMPRESSION (CREEP) OF THE Leca® Lightweight Expanded Clay Aggregate STRUCTURE IS < 2%.

With respect to the project design criteria, the Leca® Lightweight Expanded Clay Aggregate layer can be designed to fulfill several objectives at one time: to provide frost insulation, to block capillary water rise and to function as a drainage layer.

In areas prone to mining subsidence or where ground conditions contain natural sub-formation voids, drainage, culvert or tunnels and there is a danger of collapse, expensive techniques such as load transfer are often considered.

Railway embankments using Leca

However, using Leca® Lightweight Expanded Clay Aggregate can eliminate these costs and considerably lighten the load to provide similar benefits to those when used in weak soil areas.

 

(Video) Leca® Lightweight Expanded Clay Aggregate was used to develop the East Moor Bridge for Wakefield Council. The Leca® Lightweight Expanded Clay Aggregate runs behind the bridge abutment cill beams and is retained by sheet piled wingwalls at either end. For this project it was critical to complete this engineering project at speed - with time being a key factor - Leca® Lightweight Expanded Clay Aggregate provided the ideal solution through its lightweight properties and speed of delivery.

 

When constructing over weak underground voids or soils with low bearing capacity, the load compensation method may be considered using Leca® Lightweight Expanded Clay Aggregate.

By extracting a volume of existing soil from beneath the new construction, the equivalent volume of Leca® Lightweight Expanded Clay Aggregate replacing that soil will reduce the load on the subformation by four times. By using Leca® Lightweight Expanded Clay Aggregate, extraction can be kept to a minimum in order to achieve nil settlement.

Milton Keynes Rail Case Study
Rail embankment utilising Leca® LWA

Leca® Lightweight Expanded Clay Aggregate IMPROVES THE STABILITY OF THE SOFT SOIL SUBGRADE BY REDUCING THE LOAD IMPACT.

When Leca® Lightweight Expanded Clay Aggregate is applied to improve stability; the following design aspects shall be taken into account:

Properties of underlying subgrade and its loading history:

  • Pore water pressure
  • Groundwater and/or perched water level and possible open  water level
  • Inclination of ground surface or soil layers and possible river bed located beside the structure
  • Required safety factor of structure against collapse
  • Dead and live loads
  • Adjacent buildings and foundations

Principles of subgrade stability improvement by Leca® Lightweight Expanded Clay Aggregate are shown in Figures 1.1 and 1.2. Sliding surfaces emerged in a road embankment and stresses of a subgrade produced by rock fill and Leca® Lightweight Expanded Clay Aggregate fill are presented in different colors. Red lines indicate the sliding surface and subgrade stress created by conventional rock. Green lines show the sliding surface of the fill structure implemented with Leca® Lightweight Expanded Clay Aggregate and the additional stress impacting the subgrade.

1.1 Load reduction using Leca® LWA to improve stability. Subgrade stress by rock fill is marked with the red line; subgrade stress by Leca® LWA is shown with the green line.
1.1 Load reduction using Leca® Lightweight Expanded Clay Aggregate to improve stability. Subgrade stress by rock fill is marked with the red line; subgrade stress by Leca® Lightweight Expanded Clay Aggregate is shown with the green line.
LEca embankment next to water
1.2 Road structure adjacent to water channel. Construction of heavy rock fill structure in similar conditions is not possible without subgrade reinforcement measures.

 

 

We have a team of representatives in the UK with extensive experience and knowledge on utilising Leca® Lightweight Expanded Clay Aggregate on a variety of Geotechnical Civil Engineering projects.

 

For more information and a free consultation on Leca® Lightweight Expanded Clay Aggregate contact Leca® UK

TEL: 0844 3351770 

EMAIL: enquiries@leca.co.uk

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