Anti-personnel landmines pose a serious threat to modern soldiers, leading to amputations and even fatalities. These mines also cause devastation among civilian populations long after conflicts end. To counter this danger, manufacturers have developed anti-mine blast boots.
Designing anti-mine blast boots requires an understanding of the physics behind blast injuries and the use of a biofidelic human leg model for testing blast mitigation solutions. These models can be mechanical, cadaveric, or computer-generated (finite element method).
It’s not enough to design a boot that withstands a blast wave; understanding how the blast wave and associated forces interact with the human body is crucial. Recent developments in biofidelic finite element models have enhanced our understanding of these interactions.
Blast Waves Cause Injuries
Anti-mine protective footwear is designed to protect against injuries caused by blast waves and offers varying levels of fragmentation protection. Even simple blast mines produce fragments, typically encased in polymer materials. These hard plastics can be effective penetrators.
The best protection against blast waves is distance. Blast overpressure and delivered impulse decrease rapidly as the distance from the point of detonation increases. The energy density within the blast wave front decreases in relation to the cube of the distance (1/r^3). Thus, doubling the standoff distance reduces the blast wave energy density to one-eighth of its original value.
Blast wave physics and propagation are complex. Reflections from smooth and hard surfaces significantly enhance reflected overpressure, and closed spaces increase pressure levels.
In mine explosions, the blast wind resulting from overpressure causes injuries and fatalities. Distance is your best ally against blast waves. Additional survival strategies include avoiding walls and structures that enhance the blast effect and minimizing body surface area by lying parallel to the blast wave propagation direction with feet facing the point of detonation.
Thermal Effect
The newly designed Energetics Technology’s Anti-Mine boots PPE 100 are designed to withstand 75g TNT and anti-personnel mines with fragmentation. (Image: Energetics Technology Ltd.)
Blast overpressure is not the only mechanism through which explosions affect the human body. Thermal effects also cause burns, classified as quaternary injury mechanisms.
Soldiers must wear non-flammable clothing, from underwear to combat uniforms. It is essential to provide the best possible survival tools for our protectors. Unfortunately, many armies still use combat uniforms and clothing that do not adequately prevent burn injuries, with some igniting like candles, which is unacceptable.
The risk of severe burn wounds has increased in recent conflicts. Despite abundant information from past operations in Iraq and Afghanistan, lessons about burn injuries tend to be forgotten over time. The importance of burn injury protection must be continually emphasized.
Cost is always a factor in military equipment, including fire-resistant clothing. However, healthcare costs far exceed the costs of fire-protection clothing if burn injuries are not prevented. Burns can lead to life-threatening infections, organ failure, lifelong pain, disability, disfigurement, and severe mental health issues, including an elevated suicide risk.
Blast Mitigation
There are various strategies to dampen the effects of blast waves. Distance from the explosion provides the best protection, which many anti-mine boots achieve by increasing the foot’s standoff distance from the ground. This delays and reduces the blast wave’s intensity and the force exerted on the leg.
Using blast-mitigating materials is another method. These materials absorb the blast wave’s energy through deformation. Metal foams, particularly aluminum foams, are effective due to their energy absorption through crushing and densification. However, they require significant volume.
Composite materials also play a role in blast mitigation, absorbing energy through bending, delamination, and fibre breakage.
A third method involves using a blast deflector plate at the bottom of the boot, typically in a V-shape configuration. Proper positioning is crucial as some designs may inadvertently intensify the blast wave.
Spider boots, which distance the point of detonation from the foot, offer a dual blast mitigation strategy by raising the leg off the ground. While effective, these boots are not suitable for the average soldier, as walking in them proves to be quite difficult.
Finding a balance between mobility and protection is essential. An average soldier needs lightweight solutions, while a demining soldier can afford heavier boots. Ultimately, it is impossible to protect against every conceivable threat, and casualties are an inevitable part of war.
Protection Brings Weight
Various anti-mine blast boot models offer different protection levels. Increased protection typically results in heavier boots with reduced mobility.
Blast boots usually protect against explosions equivalent to 25 to 75 grams of TNT, suitable for small to medium-sized anti-personnel mines. Heavier mines, containing over 200 grams of explosives, are designed to kill rather than injure.
Injuring a soldier is often more strategically effective than killing, as it requires two additional soldiers to assist the injured. However, some armies neglect their injured, leaving them behind.
Importance of Standoff
To illustrate the importance of standoff distance, blast parameters were calculated for a 60-gram TNT explosion, simulating a medium-sized anti-personnel mine. Using the Kingery-Bulmash blast parameter calculator for a hemispherical surface explosion, the results are as follows:
Table 1. Blast wave parameters for 60 grams TNT explosion.
| Distance (cm) | Incident Pressure (kPa) | Shock Front Velocity (m/s) |
| 5 | 29670 | 5178 |
| 10 | 12624 | 3423 |
| 15 | 7266 | 2618 |
| 20 | 4711 | 2138 |
| 25 | 3242 | 1797 |
| 30 | 2320 | 1536 |
| 35 | 1712 | 1333 |
| 40 | 1296 | 1171 |
Curve 1. Pressure curve for 60 grams TNT explosion.
Stormtrooper X
The modern battlefield is becoming increasingly hostile. Nordic Defence Review is inviting the defence industry to share ideas about the protection needed by a soldier on today’s battlefield. We are calling this universal soldier concept the Stormtrooper X.
We are not just discussing ballistic protection but also protection from a multitude of threats, including CBRN (Chemical, Biological, Radiological, Nuclear) protection, anti-personnel mine protection, burn injury threats, and more. We are confident that modern material technology can provide optimized protection for these threats while remaining lightweight and integrated into combat equipment and uniforms.
One day, the infantry soldier might have to be removed from the battlefield, but until that day comes, it is imperative to invest in the well-being of soldiers. This investment will surely pay off, as the alternative involves enormous healthcare costs and human suffering. Armed forces must guarantee the best possible life for our defenders after a conflict is over.
