Structural module

A sub-base layer according to any preceding claims, wherein the height of the peripheral sidewalls is substantially less than both the width and the length of the top and bottom walls.

A sub-base layer according to any preceding claims, wherein each module further comprises a network of bracing members extending between the pillars within said enclosed volume to resist geometric deformation of said module in a horizontal plane.

A sub-base layer according to any preceding claim, further comprising an infill medium disposed within the enclosed volume of one or more of said modules.

A sub-base layer according to any preceding claims, wherein said tie members are adapted to clamp together abutting sidewalls of a pair of adjacent modules.

A sub-base structure comprising at least two sub-base layers according to any preceding claim, said layers being disposed one above the other, and a plurality of reinforcing struts connected between the layers.

A sub-base structure according to any preceding claims, wherein one or more surfaces of the modules are at least partially covered by a geomembrane or geotextile.

A structural module comprising spaced-apart, substantially parallel top and bottom walls joined by a peripheral sidewall defining an enclosed volume, a plurality of pillars extending within said enclosed volume substantially vertically between the top and bottom walls to resist vertical crushing of the module, and a network of bracing members extending between the pillars within said enclosed volume to resist geometric deformation of said module in a horizontal plane, said top and bottom walls, said sidewall and said network being apertured to allow fluid flow both vertically and horizontally through said module.

A tie member for connecting a pair of structural modules, said tie member comprising an elongate member having a substantially constant cross sectional outline of a pair of adjoined symmetrically identical trapezoids connected along the shorter of their parallel sides.