Tel: 1-206-279-3300

Upcoming Workshop Series

60 hours

Data, databases, and Machine Learning for Geotechnical Engineers

Data, databases, and machine learning for civil engineers

Sep, Oct, Nov, Dec 2020

The future of civil engineering is approaching

Online Slope Stability, Soil Nailing, and Inclinometer Monitoring Workshop

4 hours each day, 8 PDH

Slope stability, soil nailing, and inclinometer worksho

July 15, 16, 2020

Online Deep Excavation and Soil nail wall design Workshop

16 PDH

Apr. 22,23, 29, 30, 2020

Deep excavation in Las Vegas

Early registration ends soon!

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
Signup for a free trial and get our free pdf on the five most common errors in deep excavation design
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
Comparison of finite element and limit equilibrium analysis models for a 34m Deep Excavation with Three Stepped Bored Pile Walls

This case examines a 34m deep excavation with three stepped bored pile walls braced by a series of ground anchors. The excavation is in soft type rock material with an effective cohesion of 25 kPa and a friction angle of 35 degrees. The wall consists of 0.8m diameter bored piles at 2.0m horizontal spacing. The 1st and 2nd benches are at 12m and 24m depth respectively.

The excavation is analyzed with finite element and limit-equilibrium analysis methods using the DeepEX 2019 model. In limit-equilibrium methods, apparent earth pressures with FHWA and EAB are both examined. Interaction effects are also taken into consideration between the upper and lower walls. Traditionally, engineers assume a portion of the passive pressures from an upper wall acting as additional load on the front walls. When wall embedment safety factors are more than adequate (even with minimal wall embedment), a common approach is to adjust the additional impact loads to reflect closer operating conditions. A finite element simulation is also performed to consider a more detailed interaction between soil and structures. The comparison between the two models is summarized below:

Finite element vs limit equilibrium analysis summary for deep excavation

Reviewing only the overall critical results could lead one to conclude that the results are similar. Upon closer inspection the LEM approach shows smaller loads in the upper wall and cannot recognize prestress forces in the 2nd row of ground anchors at each wall. As a result, the LEM approach in this case can only be considered as a rough guide or back check. The FEM approach on the other hand is able to capture the accumulated displacements on the upper walls as a result of subsequent excavation progress.

Finite element analysis of a 34m deep excavation with three wall tiers

Finite Element Analysis of 34m deep excavation with three wall tiers

Limit-equilibrium analysis of a 34m deep excavation with three wall tiers

Limit Equilibrium Analysis of 34m deep excavation with three wall tiers

DeepEX Free trial

DownloadDownload a free trial