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Data, databases, and Machine Learning for Geotechnical Engineers

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Online Slope Stability, Soil Nailing, and Inclinometer Monitoring Workshop

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July 15, 16, 2020

Online Deep Excavation and Soil nail wall design Workshop

16 PDH

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Deep excavation in Las Vegas

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DeepEX 2020

Solving Deep Excavation Design

DeepEX 2017 talk to it and design your deep excavation!

Deep Foundation Software, Pile Rafts, Pile Groups

From soil estimation to axial and lateral pile capacity

DeepFND - Deep Foundation Software, caissons, CFA, drilled piles, driven piles, concrete, timber

From soil estimation to helical pile settlement estimation.

New helical pile software HelixPile
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What do you want to design?
DeepFND 2020: Deep Foundation software (NEW: Pile-Group/Pile Raft Analysis!)
DeepEX 2020: Deep Excavation software
Soldier pile walls
Sheet pile walls
Secant pile Walls
Tangent piles
Diaphragm Walls
Soldier and Tremied Concrete
Soil Mix walls
Combined king pile sheet piles
Slope stability
Cost estimation for braced excavations
Waler-Strut Cofferdams
Snail-Plus 2019: Soil nailing - soil nailing walls
SiteMaster: Inclinometer software (adopted by Geokon)
HelixPile: Helical Pile Software
RC-Solver: Concrete Design ACI-318, EC2, EC8
Steel-Beam: Steel beam column design, full equations, AISC, EC3

Reanalysis of metro excavation in Taipei with diaphragm wall and steel struts

An 18m deep excavation supported by a 1m reinforced concrete diaphragm wall and steel struts in soft to medium stiff clays, in Taipei was reanalyzed with the DeepXcav software program. The excavation was originally presented in a paper by Hsiao-Chou Chao, Richard N. Hwang, and Chung-Tien Chin (Moh and Associates), in the 2010 earth retention conference 3 (Aug 1-4, Bellevue, WA). In the original publication, the authors presented a methodology for correcting inclinometer displacements for walls that are embedded in clays where inclinometers do not extend beyond the wall base. The authors presented an analysis with a popular finite element analysis software program. The purpose of the analysis was to reanalyze the excavation with our software DeepXcav and compare results with the presented finite element analysis.

The diaphragm wall was 1.0m in thickness and was supported by five levels of struts. The struts comprised mostly of double H-beams braced at regular intervals. Assumed soil properties are summarized in table 1:

Table 1: Assumed soil properties in deep excavation re-analysis simulation in Taipei

Soil properties assumed in analysis for Taipei excavation with diaphragm wall and struts

Initial excavation model for 18.5m deep excavation in Taipei

In DeepXcav clay strength is modeled with assumptions that can simulate both OC and NC response. In this case, the undrained shear strength Su is treated as a maximum cutoff value, while the exact response is determined from the defined OCR at the borehole level using the peak and constant volume friction angles. For clays, the peak friction angle is used at the OC envelope and helps determine the effective cohesion at each overconsolidated point, while the constant volume shearing angle is used at the normally consolidated region.

Tables 2 and 3 compare strut reactions as predicted from the finite element and DeepXcav analysis. Depending on the assumptions made for OCR strut reactions can differ by as much as 40%, but results are still comparable with the reported finite element simulation.

Table 2: Comparison with slightly OC soils                                                        Table 3: Comparison with mostly NC response

Strut loads from finite element analysis for diaphragm wall excavation in Taipei Comparison of strut reactions from finite element and DeepXcav analysis for a braced excavation in Taipei

Wall displacements are more comparable against measured data when NC response is considered. Concluding, displacements and support reactions are in reasonable agreement with the reported finite element analysis.

Wall displacements with DeepXcav for an 18.5m deep excavation in Taipei

The following figure presents the full model in the final excavation stage with DeepEX showing wall bending moments and horizontal wall displacements:

Excavation in Taipei with opposite diaphragm walls and steel struts in DeepXcav software

Excavation in Taipei with opposite diaphragm walls and steel struts in DeepXcav software

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