3003 W CASINO RD BLDG 40-23 Geotech Report 2025-01-22

APPENDIX i, Foundation improvements for the 777X HBL positions inside of Building 40-23 will require strict slab deflection tolerances as discussed previously in this report. GeoEngineers evaluated subgrade reaction springs to support the structural engineering analyses using PLAXIS 3D Finite Element Analysis software. Detailed dead and live loads were provided by BRPH for the HBL position arrangement and are shown in Figures D-1 through D-3. The dead loads vary from 0.18 kips/feet to 25.2 kips. The live loads vary from 0.9 kips to 27.0 kips for the moving equipment_ PLAXIS 3D V21 developed by Bentley Finite Element Analysis was used to evaluate the modulus of subgrade reaction beneath the proposed 4-foot-thick mat foundation. The analyses consider soil -structure interaction for the subsurface conditions beneath the 40-23 Building area. We completed a PLAXIS 3D Finite Element Analysis to develop subgrade reaction springs for a 4-foot-thick mat foundation supported on the observed weathered glacial till and glacial till soils. Our modeling efforts accounted for the variation in weathered glacial till thickness beneath the eastern areas of Positions 5 and 6 observed in borings B-7 and B-9 as both 7-feet and 13-feet thicknesses. Position 7 assumes only glacial till is present. The assumed material properties of the subsurface soils and concrete mat are summarized in Table D-1 and are based on our past experience on site. All of the soils were modeled as elastic materials because the soil behaves elastically when the deformation is small. The PLAXIS 3D model developed is presented in Figure D-4. TABLE D-1. SUMMARY OF MATERIAL PROPERTIES USED IN MODEL Vs Unit Weight G E Material (ft/sec) V (pcf) (psi) (psi) Weathered Glacial Till 1,000 0.3 120 26,958 70,091 Glacial Till 1,500 0.3 130 63,082 164,014 Concrete Mat (fc'=6000 psi) 0.15 150 1,919,653 4,415,201 Notes: ft/sec = feet per second: pcf = pounds per cubic foot: psi = pounds per square inch The subgrade reaction springs were developed by simulating the three loading scenarios for different portions of the slab according to the loading plans shown in Figures D-1 through D-3. Note that while the loading plans shown are for Position 1, we understand from discussion with BRPH, the project structural engineer, that the same loading applies for Positions 5 through 7. All dead loads were modeled in all cases. Live loads were only applied in the loading cases shown in the three figures. The subgrade reaction spring was calculated using the pressure exerted on the soil underneath the slab and the deflection of the soil. The PLAXIS 3D model set up is presented in Figure D-4 and results for both weathered glacial till thicknesses encountered in the new explorations (7-feet and 13-feet) are presented in Figures D-5 and D-6, respectively_ The subgrade reaction springs have a uniform average of 475 pounds per cubic inch (pci) under the mat foundation at Positions 5 through 7. GWENGINEER June 15, 2022 Page D-1 File No. 0124-294-02