GoldDredger
Civil/Environmental
- Jan 16, 2008
- 172
Here in Texas we have expansive soils, lots of clay. Under normal circumstances only the first foot or two of soil is affected seasonally, drying then re-moistened with the associated movement.
The last 2-3 years have been a record drought, where it's suspected the soil was dried out to a much greater depth. With the fair amount rain this year, many newly constructed sites are seeing considerable heave in the soil as the lower soils get moisture re-introduced.
On one site we designed, the foundation of the building was constructed with pier and beam, so the finished floor has remained stable. However all of the site concrete and grading outside the building is seeing considerable uplift, 1-2 feet in some cases.
As a result the many of the sidewalks have raised higher than design, and in some cases created problems at the interface between slab on grade and structural sidewalk (part of foundation) at the doorways. Not to mention that the drainage away from the building is supposed to be 2%, along with roof downspouts draining to grade. Well since the ground has heaved, in some cases now the drainage is back towards the building.
The geotech report really doesn't offer much by way of warning. As the site civil engineer we provide various grades and spot shots to be met. The contractor claims they installed it per design, but the ground then moved.
Who's to blame, or who's responsible?
The last 2-3 years have been a record drought, where it's suspected the soil was dried out to a much greater depth. With the fair amount rain this year, many newly constructed sites are seeing considerable heave in the soil as the lower soils get moisture re-introduced.
On one site we designed, the foundation of the building was constructed with pier and beam, so the finished floor has remained stable. However all of the site concrete and grading outside the building is seeing considerable uplift, 1-2 feet in some cases.
As a result the many of the sidewalks have raised higher than design, and in some cases created problems at the interface between slab on grade and structural sidewalk (part of foundation) at the doorways. Not to mention that the drainage away from the building is supposed to be 2%, along with roof downspouts draining to grade. Well since the ground has heaved, in some cases now the drainage is back towards the building.
The geotech report really doesn't offer much by way of warning. As the site civil engineer we provide various grades and spot shots to be met. The contractor claims they installed it per design, but the ground then moved.
Who's to blame, or who's responsible?