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MECHANISED SUPPORT |
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Mechanised Demining Support NeedsMachinery can speed up aspects of demining work by supplying more force and power to the job, and by providing a level of protection to the operator in his cab. For a very comprehensive survey of machinery and applications see http://www.sya.de/demin/demin-en.htm This paper classifies machinery by application, though some machines can service several applications with appropriate modifications. It provides a review of existing machinery (incomplete) and suggestions for meeting future deminer needs. 1. Mine Neutralization1.1 Mine neutralization by force or impactThe flail principle originated in the 1940's and has been used for mine clearance in many places. A rotating shaft has several chains attached. Hammers on the ends of the chains beat the ground, setting off mines. Experience in Afghanistan and elsewhere shows that they are expensive for mine clearance (typically up to $2-00 per sq m), difficult to maintain in the field, and have required many modifications. They can be useful on carefully selected areas. Avoid rocky, uneven and hard ground, tracks and roadways. Detonation of AT mines typically causes one or two chains to be lost. In dry conditions, the chains create dense clouds of dust. Recent designs incorporate control of air flow to keep dust clouds away from the driver's view.
Photographs of the Belarty Universal Demining Machine UOS-155 BELARTY, which were taken on December 7, 1996 in CERIC village - Eastern Slavonia (UNTAES area), Croatia. The machine was deployed with SLOVENGBAT of UNTAES (Slovakian engineer battalion) together with Croatian demining company MUNGO'S to demine the village inside the former separation zone between Serbs and Croats. You can see the high bush where for deminers is very difficult to go. This is a large and heavy machine mounted on a T55 tank chassis (approx 50 tons). The boom enables the vehicle to have a large reach - up to 12 metres, which makes it possible to handle embankments, cuttings, and other areas of ground which cannot be reached with conventional flail machines. Photographs kindly supplied by Juraj DORKO, LtCol ret,, Technopol.j.s.c., Kutlikova 17, 852 50 Bratislava, SLOVAKIA, tel: + 421 7 829 995, fax: + 421 7 813 132, e-mail: juraj_dorko_sk@hotmail.com Mini FlailsRecently, several companies have developed mini-flails designed principally for dealing with AP mines. Examples include a machine developed under the US Army Humanitarian Demining Program - http://www.demining.brtrc.com/catalog/catclear1.htm 1.2 Mine neutralization by ground millingAn alternative principle for mone neutralization is ground milling. These machines have been developed for two principle applications: a) Reducing tree stumps and roots inplantations to chips before planting new saplings (young trees). b) Stripping the surface from road pavement before covering with a new surface.
The diagram illustrates the principle used by the UNO Coporation machines in the form of an hydraulically driven attachment to a large hydraulic excavator machine. Buried mines are first struck on the edge by the high speed cutter bars which chip pieces off rather than operating the fuse mechanism. A large machine of this kind was built by Bofors of Sweden (below). This machine demonstrated a clearance efficiency of about 90% on one trial, but is now under further development in Sweden. It weighs about 55 tons which makes transportation difficult.
Apart from terrain limitations, ground milling machines must be used with care. If heavy rains fall within a few months of use, sloping ground could become unstable and erode away causing environmental problems. In southern Africa, a machine based on similar principles has been used to assist clearance of dense perimeter minefields around towships. Manual clearance can be easier after the vehicle has passed because the ground is softened by the machine's action. 1.3 Deminer Needs - Mine Clearance MachineryAt the FY1998 US Defense Dept Workshop on Humanitarian Demining Needs in Washington, deminers expressed the need for machinery which not only breaks up mines, but which also removes the fragments. Without this, post-clearance inspection is very difficult. CambodiaIn late 1997, CMAC (Cambodia) issued a statement of requirement for demining machinery. The complete document is available. An excerpt lists the basic requirements (from section 8):
The desired weight is 10 tonnes, maximum is 15 tonnes. The requirement spells out in detail a deminer's wish list of capabilities. Informed opinion suggests that it would be difficult to meet all of these, but it represents a useful contribution. One interesting problem addressed by this requirement is dealing with termite hills to 4 metres diameter with trees up to 35 cm growing in the middle. The machine is required to remove the hill (and tree) flush with the ground (sect 9.13). Other important requirements concern transportation (a reasonable transit speed is needed), damage to road surfaces (especially with tracked vehicles), road and bridge capacity, and transporter ground clearances and cornering radius. One of the most important aspects of deminer needs (born out by experience) is adequate maintenance backup and spare parts delivery. Given that many countries have erratic economies in post-conflict situations, this suggests the deminers using these machines form supply routes of their own to nearby "stable" countries with reliable delivery schedules. AfghanistanMACA (Afghanistan) have a need for a ground milling/flail device or an agricultural ground tilling device. However, an electromagnetic separator is essential for removing magnetic metal fragments from the tilled ground so make the task of manual checking afterwards feasible and cost-effective. At UWA we will be testing a magnetic device in March 1998. 2. Digging, Stripping and ExcavatingOne of the most effective mechanized operations in Afghanistan demining has been the use of back hoe excavators.
These machines have been used for the following tasks:
The cab is armoured with 6mm steel plate. An attempt to add more armour caused the vehicle to become top heavy. There is an urgent need for light weight composite armour for vehicles like this in case artillery rounds are detonated by the operator. The windows consist of multiple layers of polycarbonate sheet rather than a single sheet of impact resistant material. The reason for this is that most explosions cause minor impacts which damage but do not penetrate the outermost sheet. After such an explosion, only the outermost layer needs to be replaced which is much cheaper. 3. Vegetation RemovalOne of the first machines to be tried specifically for vegetation removal is a mulcher developed by the German NGO MGM in Angola:
This machine reduces vegetation on overgrown roads to chips before the ground is checked by dogs or metal detectors. It is mounted on a type of South African mine-proof vehicle (a Wolf). For more details, refer to MGM web page (under MGM Live, editions 8 - 10 1997) Similar concepts have been tested by HALO Trust in Cambodia. UNO Corporation of Japan have demonstrated their ground milling machine performing vegetation removal in Cambodia.
Flails have demonstrated limited ability to reduce vegetation problems. The "Tempest" machine (above, in Cambodia) being developed by Warwick University shows some promise. CMAC's statement of requirements for demining machinery also specifies a vegetation removal requirement, calling for the ability to remove trees with stems to 40 cm diameter. MACA (Afghanistan) have a need for a vegetation trimmer which can operate from the side of a tractor (which can be provided with light weight armour). Commercial Forestry MachinesCommercial forestry machines, fitted with lightweight armour against fragmentation, could be very useful for vegetation removal and greatly increase operation speeds. The following photographs show a Bell buncher/cutter from South Africa. The weight is approximately 15 tonnes, and cost about US$180,000. The cab is air-conditioned. Existing protection is designed for falling trees and branches. It is capable of cutting and lifting trees to about 20cm diameter (or more), but large trees have to be allowed to fall. Then the machine can cut them up and load the pieces onto another vehicle. The maximum boom radius is 5 metres. A larger machine can handle much bigger trees with a boom radius of 15 metres.
Here the jaw is opened (close-up picture). A chain saw in the base cuts across the stem (or stems) when the jaws are closed (click for close-up). The cab is air-conditioned with modern joystick controls (click for picture)
New ConceptsOne technology which might be able to assist with several aspects of vegetation removal is abrasive water jets. Water jets which entrain sand and grit can cut through steel, concrete and stone with ease. They will also cut through mines and fuses without detonating them. Such a concept could provide a useful tool for deminers coping with thick vegetation, even trees to the diameter requirement stated by CMAC. Research and testing is needed to confirm that this concept will work in practice.
This is a concept diagram showing a buncher attachment mounted on the arm of a hydraulic excavator (to the right). The bunch opens its arms and moves forward and then closes the arms to grasp a buch of vegetation (bamboo etc.). A water jet under the buncher then slices through the bottom of the vegetation, which is then lifted clear and deposited to the side of the vehicle, ready to be removed.
These three sketches emphasize that vegetation roots cause as much of a problem as the visible parts above the ground. Roots will grow around, under and over buried mines making it difficult and dangerous to excavate them. Here a water jet can help again, because it can easily slice through roots and soil, even the mine itself, without causing a detonation. In the concept drawing shown above, the water jet is mounted on a turning arm which causes it to cut a conical section from the ground.
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