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Segmental Block Port Wall - Design example with QuayWalls Software

A. Introduction


In this example we will design a port Quay wall (segmental block wall). The initial general surface is at El: -60ft and the water table is at El: 0. We will examine the quay wall construction over a soil embankment, with a backfill behind the wall to El: 10ft. We will test the generated model under wave and seismic pressures. Such models can be simulated either in DeepEX software (the Gravity Walls and Sea Walls additional modules are required), or in our QuayWalls design software. The model will be analyzed with the DeepEX software, using the Limit Equilibrium Analysis method (LEM).


Figure: The project quay wall model in DeepEX and QuayWalls programs


B. Generate the Model with the Software Model Wizard


Our software programs DeepEX and QuayWalls include a powerful model wizard that can be used for the creation of any model with all construction stages in minutes. Within the Wizard, the user can define several project parameters and assumptions in a series of user-friendly dialogs. We can select the created wall type and wall section properties, the soil types and stratigraphy, they use of external surcharges and mooring loads, the assigned design standards, and load combinations and more. This procedure saves us a tremendous amount of time and effort to generate a detailed model.

Figure: DeepEX and QuayWalls Model Wizard Options and Settings


C. Soil Properties and Soil Layers (Stratigraphy)

Inside the software, we can create all soil types and define the soil properties in the Soil Types dialog. The DeepEX and QuayWalls Custom Layers tool is used, so we can create the custom lines simulating the relief zone behind the quay wall, as well as the soil embankment below the wall.


Figure: Soil Properties and Soil Layers


D. Quay Wall Section


In this example we will use a segmental block gravity wall section to simulate the quay wall. Both in DeepEX and in QuayWalls software, the blocks are generated automatically from the model wizard, based on the initial user model assumptions. The user can access the structural section after the model is generated and define the actual size and location for each block, as well as any potential preferred block inclinations.


Table: Wall Properties


Figure: Quay Wall Section Properties - Dimensions


E. Wave Pressure Methods & Assumptions


QuayWalls and DeepEX (with the Sea Walls DeepEX add on) can calculate wave pressures with a number of established methods – Goda, SainFlou, Allsop, Coastal Engineering Manual 2011, PROVERBS and more. The initial wave heights and wave lengths can be estimated with implemented recommendations, or manually defined by the user through a user-friendly dialog. Finally, QuayWalls can automatically estimate overtopping flow rates since it can perform average overtopping volume calculations using PROVERBS equations.


In this particular example, we will make the following assumptions:


Wave Pressures Method: Goda


Critical Wave case: Wave is lower than the water table


Wave options: Selected from CEM 2011 – Part II suggestions – Individual Thunderstorm


Ignore Overtopping


Seaward: SainFlou as modified by McConnell


Wavelength: 100ft

Figure: Wave Pressures options


F. External Loads & Seismic Pressures Settings


External Strip Surcharge


We will define a 0.6ksf variable strip load on the retaining side of the quay wall system.

Mooring Loads


In DeepEX and QuayWalls software, we can define different mooring load magnitudes in different construction stages (operating, high/low wave conditions and seismic). We can use the model wizard, so the load is adjusted in each construction stage, or draw a load on the wall and edit the magnitude and load type manually through the stages.

Seismic Options


In DeepEX and QuayWalls we can select to use seismic loads in any construction stage (typically the last stage). In the seismic stage of this example, we will calculate the seismic pressures according to the Mononobe-Okabe method for frictional soils. We will assign a 0.1g horizontal earthquake design acceleration.


G. Analysis Settings and Design Standards


1. Analysis Method -> Limit Equilibrium Analysis


2. Water Pressures -> Hydrostatic


3. Wall Friction -> Use 50% of the Soil Friction for the active side of the quay wall

4. Structural Design Codes: ACI 318-19 and AISC 360-16 Allowable

5. Slope Stability Analysis Options -> Morgenstern-Price Method (General Limit Equilibrium), Circular Slope Surface


H1. LEM Analysis Results - Moment & Shear Diagrams


Figure: Wall Moment and Shear Diagrams, Operating Conditions

Figure: Wall Moment and Shear Diagrams, Low Wave Conditions


H2. LEM Analysis Results – Wave and Seismic Pressures

Figure: Soil Pressures and Wave Pressures Diagrams, Low Wave Conditions


Figure: Seismic Pressures Diagram, Extreme Event (Seismic) Conditions


H3. LEM Analysis Results –Block Bearing & Rotational FS, Slope Stability

Figure: Wall Displacement Diagram, Block Bearing, Rotational & Passive FS, Seismic Conditions


Figure: Critical Slope Surface & Slope Stability Safety Factor, Low Wave Conditions

 

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