Preliminary laboratory assessments of a lightweight geocomposite material for embankment fill application

Abstract

The cost of retaining structures used for the lateral support of roadside embankments can be significantly reduced through the use of lightly cemented mixtures of expanded polystyrene (EPS) beads and backfill soils as lightweight roadside embankment material. Four grades of residually derived sandy soils were mixed with EPS beads and the geocomposites were stabilised with 3% cement content, compacted and cured. The textural properties and shear strength parameters of dry and soaked specimens of the cemented geocomposites were determined by direct shear tests. The shear parameters and slope stability charts were used to simulate the slope of typical road embankments. The settlement potentials at different applied normal stresses were also determined. Inclusion of EPS reduced the dry density of the residual soils from an average value of 1790 kg/m3 to 1335 kg/m3. The maximum friction coefficient, tan ᴓ′, mobilised by the geocomposite specimens decreased with an increase in the soil fines content (>0.425 mm). The difference in tan ᴓ′ between the stabilised geocomposites and the natural soil was also dependent on the fines content. For an embankment height of 20 m, slope angles of 38° and 62° were determined for fine sand geocomposites in fully saturated drainage and drained conditions, respectively. Lower slope angles were determined for geocomposites made from silty, coarse and gravelly sands. A limiting embankment height of 50 m was determined for the four geocomposites. Rainfall-induced settlement of geocomposites was dependent on pre-inundation stiffness; for the range of applied stress up to 200 kPa, the settlement exhibited by the fine and silty sand geocomposites was lower than that for the coarse and gravelly sand geocomposites. Fine and silty sands make poor materials for slope embankments because of their poor hydraulic conductivity; however, fine and silty sand geocomposites have a good conductivity and friction angle to support slope embankments.

Study on the Mechanical Properties of Flexible Prefabricated Highway Structural Systems considering the Effect of Two-Way Fluid-Structure Interaction

“…In the past period, scholars at home and abroad have carried out a large number of model experiments [1][2][3][4][5][6][7][8] and numerical simulations [9][10][11][12][13][14][15][16][17] on the rainwater infltration of embankment soil, most of which are based on the traditional research of uniform penetration of embankment soil surface and slope and constant rainfall intensity, studying the safety of embankment slope and the characteristics of rainwater seepage, and mainly focusing on preventing serious collapse accidents on embankments. However, the uneven settlement of the embankment caused by rainfall [18][19][20][21][22][23][24] is a more common form of destruction in the actual use process. Although this destruction will not directly lead to catastrophic consequences, it will lead to a series of diseases such as cracking and bulging of the road surface, afecting the normal use of the road, so the research and prevention of uneven settlement of the road surface are equally important.…”