Frequently asked questions¶
What's the difference between a nail and a tie-back anchor?¶
A nail (or passive bar) is an unstressed anchor: it develops tension only as the ground around it deforms, after the mortar is grouted. A tie-back anchor is instead pre-stressed with a jack right after installation, applying a known force from the start. SRS NX designs passive nails (soil nailing): the tension force required from the anchor is the one needed to bring the slope from FS₀ to FS_des, not a pre-load set by the designer.
The calculation gives a negative FS₀. What does it mean?¶
It means the slope is already unstable as-is, before any intervention: the acting shear force exceeds the resisting one. Check the overburden's geotechnical parameters (especially φ_col and c'_col) and the inclination α: realistic values for your site almost always give a positive FS₀, even if low.
Do I have to recalculate FS₀ every time?¶
Yes, if you change a slope or substrate parameter after already computing it: FS₀ stays at its previous value until you press Calculate FS₀ again. The full calculation (Start/Calculate) first checks that FS₀ is consistent with the current data.
R_ck or f_ck: which one do I enter?¶
It depends on the design code you chose. With NTC 2018 enter the cubic compressive strength R_ck, which SRS converts to cylindrical strength f_ck with the 0.83 factor. With Eurocode the field becomes f_ck directly (no conversion: EC2 already works in cylindrical strength). See Nails and anchors.
A check is not satisfied: what do I change?¶
Every failed check shows a specific hint in the results card. In general: R.2/R.3 (bar) are solved by increasing the bar diameter φ_b or the steel grade; R.4/R.5 (mortar and bulb) by increasing the length L_a, the drilling diameter D_f or the mortar strength; R.6/R.7 (mesh) by choosing a mesh with higher resistances or reducing the i_x spacing. See the details in Design checks.
Does the calculation consume credits? And the AI assistant?¶
Yes. Calculate and the report export consume NX credits, as does every message sent to the AI assistant. There are no unlimited free operations: plan your verification calculations around your credit balance.
Can the AI assistant replace the designer?¶
No. The assistant fills in the form from a description, fetches the seismic coefficient for a location, and explains results, but it does not verify the geotechnical consistency of the project nor take responsibility for the calculation. Always review the values it sets before calculating, and the results before putting them in the report. See AI assistant.
How do I save and reopen a project?¶
From the File menu: Save generates an .srs file, Open reloads it. Projects can also be kept on GeoDropbox. See Report and exports.
In which languages is SRS NX available?¶
The app interface is available in Italian, English, Spanish, Polish, French and Romanian. The manual is published in Italian (source) and English.
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