soil nails v. soil screws for retaining walls

[fattdad]

Soil nails include a tendon that is enveloped by grout that develops shear along the grout-soil interface. Soil screws include a shaft with helicies (sp) at varying locations. Between the helicies there is limited shear capacity along the shaft-soil interface.

Consider the image below:

Consider potential failure modes:

I would think that the soil screw doesn't work quite the same.

Comments?

f-d

¡papá gordo ain’t no madre flaca!

 

[PEinc]

What grout?

 

[cvg]

PEINC - according to the OP definition, "Soil nails include a tendon that is enveloped by grout that develops shear along the grout-soil interface" Were you thinking of soil screws instead?

I would question if a torque indicator really gives you the actul capacity or if a pull test is the only way to really confirm capacity for any type of anchor.

 

[PEinc]

The OP described both types of soil nails - grouted and screw (helical) types. Soil screws are multi-helix soil nails - without any grout. The more commonly used grouted soil nails are bar tendons that are not torgued. They usually have verification tests to confirm the grout to soil bond stress.

On small helical anchor jobs, I often use the torgue value to confirm the ultimate tension capacity. On larger or more critical jobs, I will require the helical anchors to be tested with a hydraulic jack.

I have not done a screw soil nail job and probably would not want to. If you have questions about soil screws, I recommend calling A.B. Chance for technical guidance.

 

[PEinc]

Sorry, I should have typed "torqued" not "torgued." I typed a "g" instead of a "q."