The Importance of Learning Soil Modeling 

Soil modeling is a field of geotechnical and civil engineering, crucial for safety and stability of structures. By accurately simulating soil behavior under different loading conditions, engineers can evaluate the impact of environmental factors, and design more efficiently. 

Introduction 
This package is an introduction to our Soil Simulation Tutorial series. These step-by-step tutorials for soil modeling in Abaqus consist of 5 detailed projects—including paper-based models. Each project is delivered with clear, step-by-step tutorials, CAE and INP files, and supporting research papers. Advanced material models, including Cap, Clay, Mohr-Coulomb, and Concrete Damage Plasticity, are incorporated based on research papers.  

Project – 1 

Simulation embankment construction on saturate soil floor in Abaqus 

In this video, a step-by-step simulation of embankment construction on a saturated soil floor in Abaqus is presented. The soil is divided into two sections: a dry section and a saturated section. An elastic material model with Coulomb-Mohr plasticity is used for the soil. The permeability of the saturated soil is specifically defined in the material properties. 

In this analysis, Step 1 applies a soil body force; Steps 2 through 7 simulate the embankment construction; and Step 7 includes a long-duration rest step for all soil parts. During construction, the stress in the soil increases, and afterward, the pore pressure decreases as the soil dries and loses moisture. 

Project –2 

Simulation Pressure Distribution on Subgrade Soil Underlying Geocell Reinforced Foundation Bed in Abaqus 

In this tutorial, the simulation of pressure distribution on subgrade soil underlying a geocell-reinforced foundation bed in Abaqus is examined. High contact stresses generated in the foundation soil due to increased loads cause distress, instability, and large settlements. Today, geocell reinforcement is widely used to enhance the performance of foundation beds. With increased loading from high-rise structures, contact pressures on foundation soils have multiplied, leading to significant distress, instability, and settlements. Consequently, the need for soil improvement has increased markedly. 

The introduction of geosynthetic reinforcements in foundation soils is a promising solution. In this context, geocell reinforcement is a recently developed technique that offers overall confinement to the soil within its three-dimensional pockets, thereby increasing the overall rigidity of the soil bed and improving its performance. Commercially available geocells are manufactured from high-density polyethylene sheets, ultrasonically welded in a honeycomb pattern. 

The soil is modeled as a three-dimensional solid part, and the geocell is modeled as a three-dimensional shell part. To model geocell behavior, elastic data is used, while soil behavior is modeled using elastic data combined with a cap plasticity model that includes hardening. Two static steps are considered: one to apply uniform pressure from the soil above the foundation, and another to apply a normal load on the footing zone. The geocell part is embedded inside the concrete host, and a fixed boundary condition is assigned to the bottom surface of the soil. Gravity is applied to all parts in the first step along with a uniform pressure on the top surface of the soil part. A velocity-type load is selected to apply the load on the footing zone in the middle of the soil. 

After the simulation, results such as stress, strain, displacement, and stress-settlement diagrams are available.  

Project -3 

Simulation geosynthetic-reinforced soil retaining wall in Abaqus 

This tutorial explores the simulation of a geosynthetic-reinforced soil retaining wall. The soil is represented as a 2D model with elastic and cap-plasticity material properties, including hardening characteristics. The geosynthetic material is defined as a 2D wire model using an elastic beam element. 

The geotextile-reinforced soil retaining wall, with a height of 3 meters, is analyzed using a sequential construction approach in FEM, where the wall is built layer by layer. The simulation is carried out in ten general static steps—each corresponding to the addition of a new layer of soil and geosynthetic material, followed by the application of a gravity load on that layer. The geosynthetic layers are embedded within the soil model, and appropriate boundary conditions are assigned to all components. A fine mesh is recommended to ensure accurate results. The pressure distribution diagram from Sam Helvany’s book and the results obtained from Abaqus are illustrated below:   

Project -4 

Simulation concrete piled raft in interaction with soil in Abaqus 

The fourth tutorial in this package demonstrates the simulation of a concrete piled raft foundation interacting with soil. The piled raft foundation system has gained popularity in various structures, particularly high-rise buildings. In this system, the piles significantly contribute to reducing settlement and differential settlement, resulting in an economical design without compromising structural safety. In some design scenarios, the piles are allowed to yield under the applied design load. Even if the load capacity of the piles is exceeded, the piled raft foundation can still support additional loads with manageable settlements. Therefore, accurately determining the foundation’s settlement behavior is crucial, and designers must consider the combined contributions of both the raft and piles, along with their interactions within the foundation system. 

The piled raft model includes a solid part representing the raft and five concrete piles, while the soil is modeled as a three-dimensional component with elastic-plastic material properties. The simulation involves three steps: a geostatic step, followed by two static steps. In the first step, the soil weight is applied; in the second step, the piled raft is introduced into the soil; and in the third step, a pressure load is applied to both the raft and the piles. During the simulation, deformation, stress, and strain distributions can be observed. 

Project-5 
Simulation water sloshing of the buried concrete tanks in soil subjected to seismic loading 

This tutorial explores the simulation of water sloshing in buried concrete tanks subjected to seismic loading using Abaqus. Earthquakes have historically caused significant disruptions and losses to human society, making them among the most severe natural disasters. Globally, approximately 500 million earthquakes occur each year, with magnitudes of 6 or higher occurring 100–200 times and magnitudes of 7 or higher about 18 times. Although earthquake loads are typically considered in design, conventional analyses rely on simplified theories developed for retaining walls at ground level with rigid foundations. However, these methods become less effective when structures are built below the ground surface in deep soil layers. The tank, soil, and water are all modeled as 3D solid components. To model the soil’s behavior, Mohr-Coulomb plasticity and elasticity properties are used. The water is defined using the Us-Up equation of state, while the concrete tank employs the Concrete Damage Plasticity (CDP) model. A dynamic explicit step is implemented to analyze water sloshing during the earthquake event. Surface-to-surface contact is applied between the water and the tank with a nonzero friction coefficient, and the interaction between the soil and the concrete tank is also defined as surface-to-surface contact with appropriate contact properties. Fixed boundary conditions are set at the bottom surface of the soil part. During the first step, acceleration is applied to the soil, and geostatic stress is assigned to it as a predefined field.