Geo-Bullet

Born in Academy, suited for Industry

Geo-Bullet has been developed within a PhD research in the Laboratory of Geotechnics of Ghent University based on Bullet Physics Library.

Geo-Bullet is a multi-body simulation suite which is capable of simulation of Rigid Bodies, Deformable (Soft) Bodies as well as Fluids. This makes Geo-Bullet a well-suited software for a wide range of applications ranging from onshore construction to dredging and coastal engineering applications. Each of the above-mentioned three modules is explained briefly below.

>> Geo-Bullet modules

> Rigid body module

Objects exhibiting relatively large stiffness, in such a way that their elastic deformation within the range of desired forces/stresses is negligible, can be modelled as Rigid Bodies. The rigid body module in Geo-Bullet uses Contact Dynamics approach to solve the contacts between the rigid bodies.

Objects such as rock pieces, anchors or spudcans of jack-up vessels can be modelled using Rigid body

The Figure shows the irregular-shaped polyhedrons modelled by Geo-Bullet are well representative of the real-like rock pieces. This will add additional realism and consequently accuracy to the simulation results.

> soft body module

The objects that their geometrical shape changes depending on the stress fields that they are subjected to are suitable to be represented by Soft Body Module. In these objects, two arbitrary positioned points on the geometrical domain of the object can translate or rotate about each other.

In Geo-Bullet, there are two core approaches to represent the Soft Bodies: Finite Element Method; and Material Point Method.

The Figure shows a woven geotextile modelled as a Soft Body under the impact load of dropping concrete block. The geotextile is placed over a concrete chamber filled with beach sand and constrained at the periphery.

> Fluids module

Any fluid-like material such as water, mud and clay can be modelled via Fluids Module in Geo-Bullet. A parallel version of the Smoothed Particle Hydrodynamic method has been occupied to model the fluids.

Alternatively, the Material Point Method can be used to represent the fluids, mud and clay. Depending on the simulation goals and demands, it can be decided which method to be undertaken.

The Figure shows a 2D pressure-field visualisation of a cylindrical chamber filled with clay while a smaller rigid cylinder is dropping and cutting through the clay. The clay is modelled using Fluids Module.

>> How does Geo-Bullet creates a realistic soil composition?

>> In Geo-Bullet, there is a novel algorithm capable of getting the grain size distribution range of the soil/rock to be generated, and then to reproduce the same grain size distribution. The reproduction is based on a random-scheme which means every time that Geo-Bullet generates the soil/rock composition, a unique composition is reproduced.

>> Besides, the angularities of the grains (or even a portion of the composition) can be adjusted. Geo-Bullet can generate grains with various angularity and sphericity.

>> Rock Failure simulation

>> Geo-Bullet is capable of modelling crushing and breakage of rigid bodies. The breaking threshold can be attributed to the rock strength (e.g. UCS or RQD).

The video (left) shows breakage of a concrete column being hit by a rigid object. The video (below) shows the simulation of UCS test on highly weathered rock.

>> Geo-Bullet practicality

>> Having a combination of Rigid body, Soft Body and Fluids modules, enables Geo-Bullet to model every engineering scenario associated with large deformations, two-way interaction of bodies (e.g. rigid and fluids) as well as highly dynamic regimes in a versatile manner. Below are a few examples of such engineering scenarios:

Assessment of self-weight penetration of monopiles, suction buckets and noise mitigation systems when rock armours are encountered.
Jacking feasibility of jack-up vessels when surficial or buried boulders are encountered.
Damage assessment of the dragging anchors on rock berms protecting seabed cables and pipelines.

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