Interesting technique for unstable areas. Not just a layer of fabric as is usually seen.
From:
Pacific Highway: Starting over
Think of it as a giant burrito.
Actually, think of it as five giant burritos stacked on top of each other, stretching more than 600 feet and holding a combined 5,200 cubic yards of gravel. Then put a highway on top of them.
...
The "deep patch" method follows a process not used before in Clark County. Crews began by digging out the existing highway and excavating down several feet. After putting down an initial layer of base rock, workers began wrapping subsequent layers of gravel in a flexible "geogrid" fabric designed to withstand some movement without compromising stability. Lead contractor Nutter Corp. of Vancouver will eventually put in five such layers, each about one foot deep, wrapped like a gravel burrito under the highway. Driven posts will help hold the foundation in place.
From:
Pacific Highway: Starting over
Think of it as a giant burrito.
Actually, think of it as five giant burritos stacked on top of each other, stretching more than 600 feet and holding a combined 5,200 cubic yards of gravel. Then put a highway on top of them.
...
The "deep patch" method follows a process not used before in Clark County. Crews began by digging out the existing highway and excavating down several feet. After putting down an initial layer of base rock, workers began wrapping subsequent layers of gravel in a flexible "geogrid" fabric designed to withstand some movement without compromising stability. Lead contractor Nutter Corp. of Vancouver will eventually put in five such layers, each about one foot deep, wrapped like a gravel burrito under the highway. Driven posts will help hold the foundation in place.