I am working on a project in an old alluvial flood plain with liquefiable sands 40-50' deep on top of sandstone. The soils engineer has recommended helix anchors, embedded 5 feet into dense sandstone. I don't have much experience with helix anchors this deep, but have heard that the longer they...
Hi All,
I have noticed as of late that soils reports include less and less lab testing. It seems that people take some blow counts, measure the moisture and call it a day based on some loose correlations with phi values, cohesion and bearing capacity.
When do you think lab values are absolutely...
Hi All,
I am taking a poll to see what people are using for a factor of safety against liquefaction in California. We are in the Central Coast region, and it seems that many soils engineers use a factor of safety of about 1.1 to 1.3 for single family dwellings. The local jurisdiction requires a...
Hi All,
I am working on a project where an existing bridge has been built within a mapped floodplain (Zone A). There is no FEMA BFE at this site, but it is clear from other indicators that the bridge is overtopped by up to 10-15 feet during severe storms. The client wants to laterally widen...
Hi all,
I have a question regarding the definition of "significant settlement" for foundations in California. Basically, a soils report has defined a liquefiable layer of soil from about 10' below grade to 21' below grade. In a seismic event they anticipate about 1.3" of settlement due to...
I am currently working on a project where the soils engineer has called for conventional foundations in soft, expansive clay soils. (Class CH, Blows 4-9 to 41' in depth). The foundations have been deepened to 5', the level of a fairly stable water table. The soils engineer states that...
I often see the following excerpt in soils reports:
"Since water has a significant influence on soil, the natural moisture content provides an indicator of the soil's compressibility, strength, and potential expansion characteristics."
I never see any references to moisture correlations in the...
I am a civil engineer reviewing the geotechnical investigation for a foundation retrofit of a house in an area with firm to soft clays. (Blow counts of 6-12 in upper 10 feet, drastically dropping to 4-5 down to about 41 feet) Groundwater is at 5' below grade.
The only testing done has been...
