Some EU member states are stimulating these efforts through subsidy programs for the acquisition and use of electric construction machinery, among other things. Grants, tax breaks or favorable loans are intended to reduce investment costs and facilitate the switch to more sustainable technologies.

The administrations of some metropolitan areas that have joined the "C40 Cities" network have been relying on regulations and bans for urban construction projects since 2021. This is driving the use of electric construction machinery. Such cities include Barcelona, Helsinki, Stockholm, Copenhagen, Munich and Oslo [1]. Stockholm and Oslo have announced that all construction sites are to be emission-free or climate-neutral by 2030. This makes the use of conventional, diesel-powered construction machinery practically impossible.

Essentially, the following drive technologies are currently accepted as CO₂ emission-free replacements for diesel engines:

• Electric drives that use electric motors, often in combination with an electric battery storage system.
• Fuel cell units that use hydrogen as a fuel to generate electricity. Water is produced as an emission product. This technology is still the subject of research in the construction machinery sector [2].
• Hydrogen internal combustion engines in which hydrogen is injected into the combustion chamber and mixed with air. Combustion produces water and heat as by-products. However, converting a combustion engine to hydrogen requires significant modifications. Series production of such motors is planned for stationary power generators, for example [3].

The EU requirements on noise reduction for mobile machinery (2000/14/EC) and the planned tightening of the Air Quality Directive (2008/50/EC) must also be taken into account. Electric drives can make a significant contribution here.

Theory and practice
The potential CO₂ savings during operation can be roughly measured for an anchor drilling rig. With emissions of appoximately 2.65 CO₂ kilogram per liter of diesel fuel, one can calculate, based on 2000 working hours per year, and an average consumption of 10.4 l/h, with a yearly overall release of 55 t of carbon dioxide. To completely reduce this volume, the diesel-based drive system must be fundamentally changed.

The drive concepts for e-mobility have now been essentially developed and are well known. Nevertheless, the functional principles of battery electric vehicles (BEV) cannot simply be transferred to mobile construction machinery, and this applies especially to an anchor drilling rig. The main differences lie in the number and characteristics of the numerous main and auxiliary consumers, the high powered engines, the high-level energy conversion and the constant availability on the construction site.

Mobile construction machinery also differs in terms of the proportion of continuous or intermittent power requirements and the possibility of recuperation. The operating environments which are extreme at times pose a further challenge.

For this reason, how the respective construction machine will be used must be very precisely known when designing a new type of drive. It has also become clear that any existing electric drive concepts cannot be simply transferred from one type of construction machine to another. This even applies within a single category of construction machinery if they differ greatly in terms of engine output, for example.

Supplying a mobile machine with electrical or regenerative energy on the construction site is a further challenge, not only for high electrical outputs, but also in terms of the hydrogen supply.

Tests on Kelly pile drilling rigs have shown, as anticipated, that the efficiency of the electric drivetrain is significantly better than that of the diesel drivetrain. However, the uptime in pure battery operation ("off-grid") is restricted due to various factors. Longer recharging times during which the drill cannot be used must be taken into account [4].

Concept
Several requirements were placed on the electrification of the KLEMM KR 806-3E anchor drilling rig. The drilling rig was to be on a par with its conventional counterpart, the KLEMM KR 806-3GS, in terms of drilling performance and scope of application. Operation was to be as simple as possible for the drill operator so the entire operating concept (radio remote control) could be maintained. It also needed to be possible to use a construction site power supply with a connection of max. 125 A / 400 V AC, which is easy for a construction site to obtain. To safeguard against development risks, the decision was made to retain the familiar hydraulic part of the drivetrain in the initial step, including the load-sensing hydraulic circuits and the hydraulic consumers (cylinders, hydraulic motors, etc.). This is why it is called an electro-hydraulic drivetrain. It gives the user the ability of continuing to use existing drilling systems and components such as rotary drives etc.

In order to calculate the energy supply, the operating data of a larger number of anchor drilling rigs with the same output were first evaluated. Telemetry (KLEMM Datalink AIR) proved to be extremely useful for this purpose. It was found that the power demand for anchor drilling machines in the 160- to 175- kilowatt power range is a maximum of 35% on average. This is due to the typical intermittent mode of operation with interruptions due to rod changes, anchor installation, etc. Over a longer period of time, the power requirement is therefore around 56 kilowatts.

A 400 VAC / 125 A connection can deliver an electrical output of approximately 86 kilowatts. It, therefore, made sense to use a battery to cover the machine’s remaining power requirements during power peaks. This battery is automatically charged when the power requirement falls below 86 kilowatts.

To scale the capacity of this battery, real power profiles of different operating phases were superimposed in a simulation with the calculated discharging and charging capacities of different battery sizes and different power connections (125 A, 63 A, 32 A), see Figure 1.

With a gross battery capacity of 140 kWh and a 125 A connection, the objective was for continuous use of the machine to be possible without any problems under normal conditions, plus an off-grid usage time of approx. 2 to 3 hours. As the discharge capacity of the battery is sufficiently high, all drilling functions are available at maximum power in off-grid mode, not just loading, driving and maneuvering operations alone, albeit for a limited time.

The machine can also be operated using a 63 A and even a 32 A connection in combination with a battery with correspondingly longer charging times. The drivetrain can also be configured without a battery, but in this case a connection option with a nominal 250 A is required.

The on-board electrical system was designed as an 800 V DC system for the permanently excited synchronous machine. When using the battery, an isolating transformer, an insulation monitor and corresponding software ensure that the correct electrical network configuration (IT, TN-S) is maintained in addition to galvanic isolation. The rig has no onboard charger, which prevents a permanent high current flow through the battery, providing more protection for the battery.

Cooling and heating systems for the battery, the electric motor and the power electronics (inverter, line filter, etc.) are available or can be retrofitted if required.

Developing the software for battery and energy management was another comprehensive task. The software was a completely new development by KLEMM, as was the actual machine control system.

Prototype
The first step was to ensure that the personnel involved were qualified to work on vehicles with high-voltage systems. In Germany, for example, this is regulated by DGUV 209-093 (German Social Accident Insurance).

The battery, the isolating transformer and part of the thermal management system were arranged in a "backpack" at the rear of the machine. This makes them very easily accessible, see Figure 2.

The prototype of the KR 806-3E was exhibited to the public for the first time at the BAUMA 2022 trade fair and later demonstrated to an international audience of experts, see Figure 3. Further tests were then undertaken at the KLEMM plant; this included tests on inverter and filter characteristics, the cooling behavior, noise emissions and battery management. The time required for these tests and adjustments was longer than initially assumed.

Use on construction sites
After extensive training of the operating personnel, the drilling rig was used for several weeks from the end of October 2023 by BAUER Funderingstechniek on a construction site in the Netherlands, see Figure 4. Here, micropiles (diameter 152 mm, maximum depth 42 m) were installed over a length of 1.6 km for the widening of the A9 highway near Rotterdam. Right from the start, the KR 806-3E drilling rig could be used without any problems. A further eight KLEMM anchor drilling rigs with diesel drive were used on the construction site, some of them with the Datalink AIR telemetry system. This meant that the machine functions, energy management, battery status, etc. could be tracked virtually online and compared with the pre-calculated values.

As a temporary solution for the power supply while testing the KR 806-3E, the contractor had opted for a 200-kilowatt power generator instead of an on-site power connection. The evaluation of the energy flows showed perfect characteristics when charging and discharging the battery, exactly as predicted, both in wired and off-grid operation. Off-grid drilling work at full power was possible for two hours at a time.

The average consumption of electrical energy per operating hour was 32 kilowatt-hours for the KR 806-3E. On the same construction site, the diesel energy consumption of a KR 806-3GS was 93 kilowatt-hours, see Figure 5. With the same drilling performance, the energy consumption, reduced by a factor of 2.9, was even better than anticipated, as the efficiency of all components was not precisely known when the predictions were made. The construction site personnel found the noticeably lower noise emissions of the drilling rig very pleasant.

Since June 2024, the rig has been in continuous use at another site in The Hague, where micropiles are also being drilled. Here, the rig is powered via an on-site power connection. The average consumption of electrical energy per operating hour is 32.6 kilowatt-hours. The operation is running smoothly.

Conclusion and outlook
Following customer orders for further KR 806-3E anchor drilling rigs, the drive concept is currently under revision. Firstly, some electrical components have been discontinued or improved in the meantime and secondly, we have been able to incorporate our own experience. The next generation of the KR 806-3E will be less complex, but more compact and even more powerful.

The road to electrification is long and rocky. KLEMM has taken the first step. It was important to recognize who would help us move ahead and where we were going astray. At the moment, we cannot foresee complete wireless operation under real construction site conditions. Nevertheless, we have come a step closer to our goal of "zero emissions", which for KLEMM translates to reducing carbon dioxide emissions by 55 t per drilling rig annually.

 
References
[1] Keegan, M. (2021, June 23). The Scandinavian way to zero-carbon construction. BBC. https://www.bbc.com/…

[2] Bauer AG (2024, January 31). Kick-off für zukunftsweisendes Forschungsprojekt zur Entwicklung eines klimaneutralen Antriebs für Spezialtiefbaumaschinen auf Basis eines Brennstoffzellensystems. [Press release of Bauer AG. https://www.bauer.de/…

[3] Wermke, I. (2023, November 10). Deutz AG baut Wasserstoffmotoren für China. Handelsblatt. https://www.handelsblatt.com/…

[4] Borama Drilling Equipment (2023, May). Battery-powered vs. diesel-powered. Piling Canada, issue 3, 2023, 6-13.

Further information, videos and technical data on the KLEMM KR 806-3E can be found here: KLEMM KR 806-3E_Product Information

Author
Dr. Carl B. Hagemeyer
Managing Director

KLEMM Bohrtechnik GmbH
Germany

Challenges and Solutions

Himmel und Papesch Bauunternehmung GmbH, based in Bebra, is currently installing the anchors for the new power poles in the Attendorn area. Himmel and Papesch are relying on the KLEMM KR 806-3GS universal and anchor drilling rig to carry out the work. Using a ring drill bit and a down-the-hole hammer, the longstanding KLEMM customer is drilling up to a depth of 22 meters using the overburden drilling method. Given the mountainous terrain of the Sauerland region and the limited space, the KR 806-3GS is proving to be highly suitable, as it is specifically designed for such demanding conditions. Using innovative technology and robust equipment, the rig can carry out low-vibration drilling and can be used for a variety of drilling methods depending on the soil conditions. 

Environmentally Friendly and Future Prospects

The KLEMM KR 806-3GS meets strict environmental regulations and offers sustainable and environmentally friendly solutions. Equipped with an integrated diesel engine that complies with the latest emission standards while delivering high performance and low consumption, the rig also ensures reduced noise emissions. The use of biodegradable hydraulic oil reduces the risk of environmental damage in case of leaks. With the KLEMM Energy Efficiency Package and the KLEMM Power Sharing System, energy efficiency is maximized and performance utilization is optimized.

The transmission system operator is also focusing on environmental friendliness: Since the expansion of the line takes place within the existing route corridor, the impact on nature and the landscape is minimized. In addition to improving the overall system’s network, the new line will ensure efficient energy distribution. Already connected to the wind farms on the North Sea coast, the share of renewable energy on this line will increase with the gradual phase-out of conventional power plants.

The new line is scheduled to be commissioned in 2026, marking another milestone on the path to a sustainable and future-proof energy supply in Germany.

How it all started
In order to carry out drilling and blasting work to extract stone material for dam construction, Guenter Klemm founded KLEMM Bohrtechnik GmbH in 1963. During the early years, the company focused on blast hole drilling in quarries and road construction as well as injection drilling for sealing dams. Soon the company began to manufacture individual pieces of drilling equipment, such as drill bits and drill strings, for its own use.

Later on, the company became a specialist in overburden drilling. This method is frequently used in specialist foundation engineering to tie back excavation pits. To successfully manage the considerable order volume even better and faster, employees worked continually on improving the drilling equipment. The focus shifted increasingly toward the development of drilling rigs and drilling accessories.

In 1967, a milestone was achieved: Guenter Klemm invented a device for overburden drilling. He combined a deep hole hammer with a rotary percussive overburden drilling system, while also bringing together the flushing head with an excavating head. This principle considerably improved the discharge of drilling debris and remains the state of the art to this day.

From drilling company to drilling equipment manufacturer
Construction drawings from 1970 demonstrate how far Klemm had already progressed in its transition from drilling company to equipment manufacturer at the time. In 1972, Klemm entirely ceased its drilling operations. This is when the company presented the first hydraulic drilling hammer – a ground-breaking innovation. The hydraulic drilling hammer significantly enhanced performance and improved energy efficiency considerably compared with conventional compressed air methods. Guenter Klemm was informed about the details of the new anchor drilling technology by Dr. Karlheinz Bauer. Even back then, Dr. Bauer showed his first signs of interest in acquiring Klemm.

The main business was now the sale of drill strings, drilling accessories and enhanced flushing heads, particularly for overburden drilling. Klemm continuously enhanced the method of overburden drilling – all the way to double-head systems, which combined a hydraulic hammer for the drill string with a rotary drive for the external casing. Thanks to this technology, overburden drilling established itself as the standard drilling method in specialist foundation engineering worldwide.

During the 70s, Klemm developed its first hydraulic hammer with a rotary drive, the S30. The KB 40-B and KB 40-O systems came to replace the deep hole hammers powered by compressed air that had previously dominated the market. In 1974, KL Klemm EMM presented a drilling rig with a diesel-hydraulic drive, crawler and movable drilling carriage: the drilling rig type KR 800 was born.

KLEMM also registered a number of important patents in the 70s, for example frequency control of the impact piston and a protective circuit for the pressure tank. In this way, the company secured its position as a pioneer in the market. What began as a small company for blast hole drilling had become a globally positioned specialist in the development and manufacture of innovative drilling systems for specialist foundation engineering.

The 1980s
In 1980, Klemm sold the first rock crusher KB 5000. This was followed by an entire series of models. The drilling rigs had reached type KR 501 by this time. For blast hole drilling in quarry operation, Klemm developed the KR 901 series with hydraulic hammer and KR 1001 with operator’s cab, compressor, drill string magazine, down-the-hole hammer and dust extraction. One highlight in 1981 was a diving bell equipped with a rotary drive for coring work. Using this system, exploration and blast hole drilling work was carried out off the coast of Newfoundland at a water depth of 160 m in order to install a telephone cable.

The first double-head systems with hydraulic hammer marked the launch of the KR 806 drilling rig. A new boom kinematics system now also allowed for low initial drilling points. By this time, hydraulic drilling rigs and the hydraulic hammer had taken on a dominating role in specialist foundation engineering and definitively replaced drilling rigs powered by compressed air. The manufacture of Kelly drilling rigs and accompanying drilling equipment with Kelly bars, auger and bucket tools also began in the early 80s. The first pile drilling rig GH 80 was delivered in 1983.

In 1980, Klemm sold the first rock crusher KB 5000. This was followed by an entire series of models. The drilling rigs had reached type KR 501 by this time. For blast hole drilling in quarry operation, Klemm developed the KR 901 series with hydraulic hammer and KR 1001 with operator’s cab, compressor, drill string magazine, down-the-hole hammer and dust extraction. One highlight in 1981 was a diving bell equipped with a rotary drive for coring work. Using this system, exploration and blast hole drilling work was carried out off the coast of Newfoundland at a water depth of 160 m in order to install a telephone cable.

The first double-head systems with hydraulic hammer marked the launch of the KR 806 drilling rig. A new boom kinematics system now also allowed for low initial drilling points. By this time, hydraulic drilling rigs and the hydraulic hammer had taken on a dominating role in specialist foundation engineering and definitively replaced drilling rigs powered by compressed air. The manufacture of Kelly drilling rigs and accompanying drilling equipment with Kelly bars, auger and bucket tools also began in the early 80s. The first pile drilling rig GH 80 was delivered in 1983.

Reunification – Construction boom and economic slump
In 1989, Klemm was acquired by the American Ingersoll-Rand Group. During the construction boom after Germany’s reunification, construction projects in Berlin above all lead to a high demand for Klemm’s technology and equipment. In 1990, Klemm began developing equipment for thermal probe drilling. The business in directional drilling systems and directional drill strings also gained steam. The successor to the GH pile drilling rigs was the lightweight universal pile drilling rig KB 3010. The undercarriage of this rig featured telescopic circular guides, the mast had a gear rack feed and the hoists were accommodated in the upper carriage. With this development, Klemm broke free from its dependence on excavator manufacturers. A difficult phase started in the mid-90s when the exceptional boom after reunification began to slow down. Klemm had to reduce its personnel, and international subsidiaries were closed down.

Klemm and Bauer
In the midst of this crisis, Bauer acquired Klemm in 1998 and restructured its business. Since then, Klemm has been the specialist within the BAUER Group for anchor drilling rigs and accessories. Part of this restructuring meant that Klemm stopped selling pile drilling rigs, and anchor drilling rigs were no longer sold in Schrobenhausen. This allowed the former competitors to pool their synergies.

One highlight: In 2004, Klemm received an order to deliver four large automated blast hole rigs to expand the Panama Canal. They were assembled and commissioned in Panama on a floating drilling platform. Later on, a Klemm drilling rig was also used at Ground Zero in New York.

In 2005, Klemm started developing a vibratory drive. The first linear vibratory drive was tested in site conditions in 2007. With the advent of even more powerful, heavy rotation-vibration drives, new drilling technologies and carrier devices have subsequently been developed. In 2007, Klemm delivered a KR 709-1C to a site in China where coal fires near the surface had to be extinguished. The equipment proved itself under extreme operation conditions at high temperatures. China ordered three additional machines.

Alternative drives
Nowadays, electric drive concepts and smart equipment functions are paving the way to the future. The battery-powered electric KR 806-3E is Klemm’s contribution to decarbonization. This equipment features proven technology from the KR 806-3GS – the same kinematics and an adapted form of the same powerful double-head drilling systems and hydraulic hammers, but as an electrohydraulic, emission-free variant. Compared to the diesel-hydraulic variant, there are no restrictions when it comes to power and application. Thanks to sophisticated technology and robust design, Klemm systems are used under nearly all conditions worldwide, for example in foundation and safeguarding work, when constructing traffic routes above and below ground, for dam sealing and to generate renewable energy.

The task of improving a standardized machine part, such as a clamping and breaking unit, has been one such internal project carried out over the last one and a half years.

The clamping and breaking unit which is one of the most highly stressed machine elements on the drill rig fulfills numerous tasks within the drilling operation. These varying tasks call for an understanding of each individual function and how they can affect each other. The goal being to optimize the working procedure and the lifespan of these rugged machine elements.

Repositioned Cylinders
The clamping cylinders (position 1) found on both the clamping and the breaking units have been rotated by 180° to reposition the piston rods and the wiping seals out of the direct line of the drill cuttings. “This reduces the possibility of drill cuttings damaging the wiper seals and subsequently entering and contaminating the hydraulic system.” explained Martin Bonzel.

An additional benefit is, that when drilling to greater depths, the transfer of weight force from the drill string to the clamping jaws is no longer carried solely by the piston rods. The much larger cylinder outer body, which has been designed with rails to fit exactly into the unit housing, allows for the forces to be carried not only by the cylinder body itself but also by the complete clamping and breaking housing. This simple, but effective design change will substantially reduce the number of damaged cylinder rods and seals.

Improved Clamping Jaws
Fixed clamping jaws (position 2) are designed to hold a specific diameter when the contractor predominantly uses the same size of tooling on each jobsite.

The latest development is a movable clamping jaw (see positions 3) which adjusts itself according to the actual diameter of the tooling being used. This is the ideal clamping tool when a large range of different diameters are commonly used.

Jaw inserts made from carbonated high alloyed steel
New style of jaw inserts (position 4) made from carbonated high alloyed steel which will increase the life cycle of the inserts and offer more grip on the drill tool. This additional grip allows for a reduced clamping pressure, which will subsequently decrease any deformation to the threaded adapters of the drill tools.

High Wear Plastic Rails
Integrating replaceable high wear plastic rails (position 5) on surfaces with relative movement will reduce the need for subsequent costly maintenance work as the metal machine parts no longer come into contact with one another.

Open face clamping
The opening area of the clamp (position 6). In the past, the necessity for longer clamping jaws to hold augers across the pitch of its flights has reduced the maximum possible diameter of the augers. This problem has been addressed by opening up the area around the jaws i.e. a 14” clamp could previously accommodate an auger diameter of only 8 1/2”. The new opening of the passage area on the housing has enabled this diameter to be extended to 13”.

Stand Alone Unit
“Whilst taking a new look at the clamping and breaking units, we decided to design them as standalone devices” said Martin Bonzel, “This meant integrating all the necessary hydraulic valves into the unit itself and ensuring that the central height of the drill string axis to the central axis height of the rotary heads and drifters remains the same. This allows for an easy swap of complete units”.

In practice this means that when moving, for example, from a tie-back to a micro-pile jobsite, with the need to change the clamping and breaking unit from a 10” diameter to a 14”, or even 17” diameter, the units can be considered as interchangeable. This idea has not only been implemented on a particular machine model, but where possible, across the whole range of different machine models – therefore making it a truly modular system.

The clamping and breaking unit described is presently on field test in Europe and will be released as a standard product in the near future. A scaling in size to additional larger and smaller diameters is presently being undertaken.

These examples show that seemingly standardized machine elements have great potential for improvement, and when adapting them to the ever-changing requirements of modern jobsites and drilling operations much can be achieved.

Outlook into New Technologies. Zero-Emissions.
Another area of great focus is the electrification of the drilling rigs. “We are seeing more and more inquiries for electrically powered machines with the aim of reducing the carbon footprint on the construction jobsite.” Carl Hagemeyer said. Drilling rigs with electric asynchronous motors that are connected directly to the mains have been part of the construction industry for many years. The engineering challenge now is to explore the different avenues of how best to power the machines of the future.

KLEMM’s first venture into such technologies was shown in October 2022 at the Bauma exhibition in Munich.

“On our journey to Zero-Emissions we have developed a hybrid power train with a 125 A (86 kW) plug-in connection which works in conjunction with a battery backpack (140 kWh). As we know that the average energy consumption of an anchor drilling rig is about 25-35% of the installed power and considering the power consumption of the diesel-hydraulic drilling rig with 175 kW we were able to develop this hybrid system accordingly.” Carl Hagemeyer, said. The batteries act as a buffer to supply peak power needs when the 86 kW from the grid is exceeded. Once the power demand drops below the 86 kW threshold (e.g. when idling or rod changing) the excess power is used to recharge the battery. This is achieved with the help of our inhouse developed energy management software, allowing the machine to re-charge whilst operating without any downtime.

An additional benefit of the hybrid system is the “off grid operation” capability, which can be necessary in situations where the operation of the drilling rig is required without the availability of the electrical grid. Examples for such situations would be when loading or unloading the drilling rig on inner city streets or at remote locations where the machines’ access point to the construction site and the actual drilling area are some distance apart. A simple off-grid driving of the machine is then possible.

A power concept for special high-power applications is a 2 x 125 A plug system without battery backpack, which provides 2 x 86 kW (= 172 kW). So, maximum power is provided constantly. This system can be utilized effectively on jobsites when connected directly to the mains. For loading and unloading purposes the machine can be powered by an easy to come by 32 A or larger power outlet.

The first deployment of a KLEMM KR 806-3E hybrid machine is due in late spring or early summer of 2023 on a large micro-pile jobsite in the Netherlands. “Our engineers will of course be monitoring the progress and applying this field knowledge accordingly”, Carl Hagemeyer said.

Although there still lies some engineering and innovation ahead to make this Zero-Emission rig a standard drilling rig on construction sites all over the world, the progress made here is very tangible.

KLEMM Bohrtechnik looks forward to reporting on further developments in these new and exciting fields as time progresses and will finish by saying, for standard machine elements or new drive concepts, innovation never stops…..

Für die Sicherung der Stützwände am letzten Teilstück, der Umfahrung von Vahrn, ist ein KLEMM Ankerbohrgerät KR 801-3GK im Einsatz. Die Baustellenbedingungen stellen eine große Herausforderung für Mensch und Maschine dar. Große Granitblöcke müssen durchbohrt und extreme Bohrpunkte unterhalb und seitlich des Bohrgerätes erreicht werden. Daher fiel die Wahl auf das Universalbohrgerät KR 801-3GK mit leistungsstarkem Hydraulikhammer und einer – für Ankerbohrgeräte – einzigartigen Auslegerkinematik, die verschiedenste Bohrpositionen ermöglicht. Das Bohrgerät ist außerdem selbstnivellierend, d.h. auf dem besonders unebenen Gelände dieser Baustelle lässt es sich perfekt stabilisieren und erlaubt dem Bediener somit eine einfache und sichere Handhabung.

Mit dem von BAUER Macchine Italia an die Arbeitsgemeinschaft vermieteten Gerät wurden von Juli bis Ende September bereits über 10.000 m Selbstbohranker gebohrt. Die Bauleitung geht davon aus, dass nach Fertigstellung weit über 20.000 m erreicht werden.

On the last stretch of the Vahrn bypass a KLEMM KR 801-3GK anchor drilling rig is being used to secure the retaining walls. The conditions at the construction site are proving to be a great challenge for man and machine. Large granite blocks need to be drilled through and the drilling rig needs to reach extreme drilling points, both below and to the side of the machine itself.  These are the reasons why the KR 801-3GK universal drilling rig with its powerful hydraulic hammer and unique drilling boom kinematics was chosen for the job. The kinematics are especially versatile for anchor drilling, and a wide range of drilling positions is possible. The drilling rig itself is self-levelling – which means that it can be completely stabilized on the particularly uneven terrain at this construction site – allowing the operator a safe and easy handling.

The rig, which has been rented to the consortium by BAUER Macchine Italia, has already been used to drill over 10,000 m of self-drilling anchors from July to the end of September. The construction management expects that well over 20,000 m will be reached after completion.

A Construction Site with a Sea View

A five-story building is to be erected near the beach at Jesolo by the construction company Rodighiero Claudio & C. S.r.l. “The customer doesn’t normally drill the anchors himself”, explains Andrea Ruggero, Area Sales Manager of BAUER Macchine Italia, “in this case though, he chose to carry out the work on his own, and to rely on the experience and support of BAUER Macchine Italia as part of a full-service package.”

“The plan was to construct standard foundations”, added Ruggero. “This included excavation work and laying normal foundations without piles. One of the roads, however, needed to be constructed to make the site accessible to heavy vehicles. This required reinforcing the substrate using anchors. 40 mm Ischebeck titanium self-drilling anchors were installed at an angle of 45°, 10 to 13 meters deep. This technique is being used more frequently throughout Northern Italy and was selected for this site in particular due to the time restrictions of the project.” This decision has undoubtedly paid off in terms of time, and with 300 m of anchors installed in just one shift, the figures are definitely impressive.

Flexibility combined with maximal stability

It’s important to mention the technical features that distinguish the KR 801-3GK used in Jesolo. “The suffix 3G,” explains Ruggero, “indicates that the motorization complies with the current pollutant emission standards, and the “K” denotes the unique kinematics with which the drill rig is equipped. The kinematics on this rig enable positions to be drilled below the drill rig itself, and it is also capable of drilling up to 3 meters outside of the tracks.” With the KR 801-3GK, KLEMM Bohrtechnik, already renowned for their robust machines, have developed an 11 Ton, lightweight, compact drilling rig suitable for even the most complex of construction sites.

„This rig “, continues Ruggero, “has been designed for special applications. One of the rigs special characteristics is that the kinematics enable work to be carried out below the rig. This is a really interesting feature for anyone who needs to carry out stabilization measures on, for example, jetties or piers. This sort of operation would normally require working with a suspended platform or a pontoon, which can lead to significantly higher expenses. Our KLEMM, can drill boreholes below the body of the rig, both to the front and to the side, with the mast at a slightly inclined angle. The reach of the mast is especially long, enabling horizontal drilling at a height of almost 5 M from the ground. It’s basically possible to drill anchors and micro-piles in any position.”

“Even though the rig is destined mainly for drilling small to medium diameters of 70 mm, it’s actually capable of drilling self-drilling anchors up to 2.5 meters long with diameters up to 114 mm, depending on the soil type. This KLEMM rig is equipped with a KD 1011 hydraulic hammer which has a maximum torque of 11 kNm and a piston weight of 11 kg.”

Growing Machine Fleet

BAUER Macchine has expanded its rental fleet in recent years making it possible to offer the right KLEMM product to suit the wide range of drilling applications practiced in the Italian Market.

In den über 700 Jahren Ruhrbergbau gab es -inklusive aller Kleinzechen- ca. 1.300 Bergwerke im Ruhrgebiet. Allein in Bochum und Essen waren es je ca. 280, in Sprockhövel ca. 250, in Dortmund ca. 120 und erst die Einführung des „Preußischen Berggesetzes“ im Jahre 1865 verpflichtete die Bergwerksbesitzer, ihren Abbau zu kartieren und der Oberen Bergbehörde vorzulegen. Alle Bergbauaktivitäten zuvor sind daher nur schlecht oder auch überhaupt nicht dokumentiert. In der Nachkriegszeit kam es zudem noch stellenweise zu illegalem Abbau, der weitere unverfüllte Hohlräume hinterließ, die ebenfalls nicht dokumentiert sind. Die Gesamtzahl aller Tagesöffnungen und Stollen allein im südlichen Ruhrgebiet wird auf etwa 60.000 geschätzt[ii], von denen bislang nur etwa 27.000 erfasst bzw. entdeckt worden sind – verfüllt und gesichert wurde davon bis heute nur ein Bruchteil. Die Problemzonen mit akuten Gefahren durch Tagesbrüche liegen insbesondere dort, wo nur bis 100 Meter Tiefe abgebaut wurde.

Als sei dies nicht schon genug, hinterließen die Bombardierungen durch die Alliierten im zweiten Weltkrieg zusätzlich noch tausende bis heute unentdeckte Blindgänger im Untergrund. Laut eines Berichts der Pressestelle der Landesregierung NRW wurden während des 2. Weltkrieges auf das Gebiet des Deutschen Reiches 1,3 Millionen Tonnen Sprengmittel abgeworfen. Rund die Hälfte der Luftangriffe haben sich auf das heutige Nordrhein-Westfalen, davon wiederum ein hoher Prozentsatz auf die Städte mit ihren Infrastruktur- und Industrieeinrichtungen zwischen Rhein und Ruhr konzentriert. Experten[iii] gehen davon aus, dass etwa 15  Prozent der Bomben Blindgänger waren und sich daher noch deutschlandweit bis zu 100.000 t unentdeckt – je nach Gewicht, Größe und Untergrund – in bis zu max. 8 Metern Tiefe im Boden verbergen. Allein in NRW werden jährlich zwischen 2.000 und 2.500 Bomben entdeckt und geräumt. Im besonders stark betroffenen Essen geht man davon aus, daß von den dort 14.000 vermuteten Blindgängern nur gut die Hälfte noch während des Krieges und des Wiederaufbaus gefunden und entschärft werden konnten. Tausende weitere liegen dort demnach noch verborgen im Untergrund – Granaten, Handgranaten und Minen nicht mitgezählt. Von all diesen Blindgängern, sowie auch von den oberflächennahen bergbaubedingen Hohlräumen gehen daher ganz besondere Gefahren aus, die man keinesfalls unterschätzen darf. In den entsprechend betroffenen Gebieten müssen somit heute bereits vor der Aufnahme von Baumaßnahmen besondere Vorkehrungen getroffen werden. So ist der Bauherr verantwortlich für die Kampfmittelfreiheit eines Baugrundstückes und die Rechtsnachfolger der Bergbaufirmen – sofern bekannt oder noch existent – für das Auffinden und Beseitigen von Bergbaualtlasten. Ist kein Rechtsnachfolger mehr auszumachen übernimmt hier das Land NRW.

Wenn Auswertungen alter Aufzeichnungen oder Luftbilder Verdachtspunkte für Kampfmittel ergeben, wird in der Regel zunächst von der Oberfläche aus mittels Bodenradar, Geo- oder Elektromagnetik sondiert. Je nach Bodenbeschaffenheit liefern diese Methoden aber nur bis 3, in Ausnahmen bis 5 Meter Tiefe zuverlässige Ergebnisse. Hat man hier keine Treffer, kann mit der Tiefensondierung fortgefahren werden. Ein klassisches Verfahren zur Ortung von Bombenblindgängern bis 15 m Tiefe und mehr ist die geomagnetische Tiefensondierung, bei der ferromagnetische Körper (Eisen) in radialer Entfernung von im Mittel 0,75 m vom jeweiligen Bohrloch detektiert werden. So auch auf einer aktuellen Baustelle der Fima GbE Grundbau Essen GmbH in der Nähe des Essener Hauptbahnhofes. Auf dem rund ein Hektar großen Areal an der Hachestraße, wo früher die Güterabfertigung der Bahn angesiedelt war, sollen demnächst zwei Büroobjekte und ein Parkhaus entstehen.

Hier kommt ein KLEMM Bohrgerät vom Typ KR 801-3GS der neuesten Generation zum Einsatz, um im sogenannten Schneckenbohrverfahren ohne Spülung 27 Bohrungen in einem vorgegebenen Raster bis auf 8 Meter unter Geländeoberkante – zum Zeitpunkt des Kriegsendes 1945 – niederzubringen. Schlagende Bohrverfahren mit Hydraulik- oder Tieflochhämmern sind aufgrund der Explosionsgefahr der eventuell vorhandenen Blindgänger hierbei grundsätzlich nicht zulässig. Die Bohrungen haben einen Durchmesser von 120 mm, in die nach Fertigstellung ein PVC-Rohr eingebaut wird, um das Bohrloch für die anschließende Befahrung mit der ferromagnetischen Sonde zu stabilisieren. „Als Bohrmeister muss man hier sehr viel Erfahrung mitbringen, um die unsichtbaren Vorgänge im Bohrloch nur anhand vom Dreh- und Vorschubverhalten sowie der entstehenden Geräusche beim Bohren richtig zu deuten“, berichtet Timo Hölscher, verantwortlicher Bohrmeister bei GbE. „Einen Blindgänger anzubohren und damit zur Explosion zu bringen will natürlich niemand riskieren. Ein gewisses Restrisiko ist allerdings nie ganz auszuschließen. Aber die präzise und feinfühlige Steuerung der KR 801-3GS erleichtern mir schon erheblich die Arbeit und durch die kabellose Fernbedienung stehe ich in der Regel auch nicht unmittelbar am Bohrloch.“, so Hölscher weiter. Sind alle Bohrungen fertiggestellt, erfolgt die Messung durch Herablassen der Messsonde (z. B. ein Vertikalgradiometer) im Kunststoffrohr, deren Messdaten später am Computer von Spezialisten ausgewertet werden. Je nach Ergebnis wird danach der Grund freigegeben oder aber es werden weitere erforderliche Maßnahmen ergriffen.

Bei Hinweisen auf Bergbaualtlasten geht man gleich zu Erkundungsbohrungen über, sofern eine Kampfmittelkontamination ausgeschlossen werden kann. Hierbei werden ebenfalls in einem festgelegten Raster Bohrungen im Spülbohrverfahren niedergebracht. Im Gegensatz zur Kampfmittelsondierung kann dies auch in einem schlagenden Bohrverfahren durchgeführt werden, sofern der Untergrund dies erfordert. Treffer, besser gesagt angebohrte Hohlräume, erkennen die Bohrspezialisten entweder am Durchsacken des Bohrstranges oder am Versiegen des Spülungsflusses. Durch weitere Bohrungen im Umkreis eines Treffers werden Größe, Lage und Verlauf der Hohlräume festgestellt und kartiert. Bei Bedarf wird auch in diese Bohrungen ein Kunststoffrohr eingeführt, durch welches nach Abschluss der Bohrarbeiten der Hohlraum mit zementhaltigen Baustoffen verfüllt wird. „Da können auf einer Baustelle schon mal einige tausend Kubikmeter Füllmaterial zusammenkommen“, weiß Timo Hölscher zu berichten. Je nach geplanter späterer Nutzung erfolgen gegebenenfalls noch zusätzliche Injektionsbohrungen zum Einbringen von Verpressmaterial zur weiteren Baugrundstabilisierung über Manschettenrohre.

Die Baustelle an der Hachestraße liegt in unmittelbarer Nähe zu 3 historischen Zechen bzw. Schächten:

• Zeche "Secretarius Aak" – Abbau etwa 1750 bis 1805 in 50 m Entfernung
• Zeche "Vereinigte Hoffnung und Sect. Aak, Schacht Hoffnung" – Abbau 1805 bis 1897 in 150 m Entfernung
• Zeche "Vereinigte Hoffnung und Sect. Aak, Wetterschacht in Flöz Röttgersbank" in 40 m  Entfernung

Bereits bei Bauarbeiten an der Hachestraße im Jahre 2013 wurden Hohlräume entdeckt, die dem ehemaligen Grubenfeld der Zeche "Vereinigte Hoffnung und Sect. Aak“ zuzuordnen sind. Nach Erkundungsbohrungen waren damals schon umfangreiche Verfüllarbeiten notwendig[iv]. So ist davon auszugehen, daß auch auf der aktuellen Baustelle noch Probebohrungen stattfinden werden, sobald die Kampfmittelsondierung abgeschlossen ist.

Die hier eingesetzte KR 801-3GS definiert eine eigene Klasse von besonders kompakten und zugleich universell einsetzbaren Bohrgeräten. Aufgebaut auf einen Pendelraupenfahrwerk ist das Bohrgerät für nahezu alle im Spezialtiefbau vorkommenden Arbeiten optimal – von leichten bis hin zu schweren Bohrarbeiten. Serienmäßig ausgestattet mit leistungsoptimierter Hydraulik (KLEMM „Power Sharing“), dem Energie-Effizienz-Paket (KLEMM „EEP“), adaptiver Drehzahlregelung von Motor und Lüfter und effektiven Schalldämmhauben eignet sich das Gerät mit seinen geringen Emissionswerten auch optimal für den innerstädtischen Einsatz. Ergonomische Gestaltung, hohe Wartungsfreundlichkeit, ausfallsichere Maschinensteuerung mit Ferndiagnose, Bedienung per Fernbedienung sowie umfangreiche Sicherheitseinrichtungen runden das Paket ab.

So bleiben das Aufspüren und Beseitigen der Hinterlassenschaften aus Krieg und Bergbau, trotz der heute zur Verfügung stehenden modernen Maschinen und Verfahren Ewigkeitsaufgaben für viele weitere Generationen an Rhein und Ruhr.

  Wikipedia: Liste von Bergwerken in Nordrhein-Westfalen   (https://de.wikipedia.org/…)

[iv] Artikel auf „derwesten.de“ vom 27.11.2013 (https://www.derwesten.de/…)

In more than 700 years of mining, – including all small mines – there were about 1,300 mines- – in the Ruhr area. There were around 280 in both Bochum and Essen alone, plus about 250 in Sprockhövel and about 120 in Dortmund. Until the introduction of the "Prussian Mining Law" in 1865, mine owners were not obliged to map their mining operations and submit them to the Mining Authority. All mining activities before that time are therefore poorly documented or, in some cases not documented at all. In the post-war period, illegal mining also took place in some areas, leaving more undocumented unfilled cavities. The total number of openings and tunnels in the southern Ruhr region alone is estimated at around 60,000[ii], of which only about 27,000 have been recorded or discovered to date – only a fraction of these have been backfilled and secured. The problem zones with acute dangers due to sinkholes are located in particular where mining was only carried out to a depth of 100 meters.

As if this were not enough, the bombing by the Allies during World War 2 also left thousands of unexploded bombs underground, which have remained undiscovered to this day. According to a report by the press office of the NRW state government, 1.3 million tons of explosives were dropped on the territory of the Deutsche Reich during World War 2. About half of the air raids were concentrated in what is now North Rhine-Westphalia, and a high percentage of these were focused on the cities with their infrastructure and industrial facilities between the Rhine and Ruhr rivers. Experts[iii] assume that about 15 percent of the bombs were unexploded bombs and therefore up to 100,000 tons are still hidden undiscovered in the ground throughout Germany at a maximum depth of 8 meters, depending on the weight, size and subsoil. In North Rhine-Westphalia alone, between 2,000 and 2,500 bombs are discovered and cleared each year. In Essen, which was particularly hard hit, it is assumed that of the 14,000 unexploded ordnance suspected there, only a good half could be found and defused during the war and reconstruction. This means, that there are thousands more lying hidden underground – not counting grenades, hand grenades and mines. All of the unexploded ordnance, as well as the near surface mining, pose very special dangers. In the affected areas, special precautions must therefore be taken even before the start of construction work. The owner is responsible for ensuring that a construction site is free of explosive ordnance, and the legal successors of the mining companies – if known or still in existence – are responsible for locating and removing old mining contamination. If no legal successor can be identified, the state of North Rhine-Westphalia takes over.

 When evaluations of old documents or aerial photographs reveal suspected explosive ordnance, the first step is usually to probe from the surface using ground penetrating radar, geo-magnetic, or electromagnetic systems. Depending on the soil conditions, however, these methods only provide reliable results down to a depth of 3 meters, or in exceptional cases up to 5 meters. If no hits are found here, depth probing can be started. A classic method for locating unexploded bombs at depths of up to 15 m and above, is geomagnetic depth probing, in which ferromagnetic bodies (iron) are detected at an average radial distance of 0.75 m from a borehole. This is also the case on a current construction site of Company “GbE Grundbau Essen GmbH” near Essen’s main train station. Two office buildings and a parking garage will soon be built on the approximately one-hectare site on Hachestraße, where the railroad freight terminal used to be located.

Here, the latest generation of a KLEMM KR 801-3GS drilling rig is used to drill 27 boreholes in a specified grid down to 8 meters below ground level – the ground level at the time of the end of the war in 1945.  The boreholes are drilled using the so-called auger drilling method without flushing. This is because percussive drilling methods with hydraulic drifters or dth-hammers are generally not permissible here due to the risk of explosion caused by vibrations from any unexploded ordnance that may be present. The boreholes have a diameter of 120 mm, into which a PVC pipe is installed after completion to stabilize the borehole for subsequent travel with the ferromagnetic probe. "As a drilling operator, you have to have a lot of experience here in order to correctly interpret the invisible processes in the borehole – just on the basis of the rotation and feed behavior, as well as the resulting noises during drilling," reports Timo Hölscher, the drilling operator in charge at GbE. "Of course, no one wants to risk drilling into an unexploded ordnance and thus causing it to explode – but a certain residual risk can never be completely ruled out. The precise and sensitive control of the KR 801-3GS already makes my work considerably easier, and the wireless remote control means that I’m not usually standing right next to the borehole," continues Hölscher. Once all the boreholes have been completed, the measurement is carried out by lowering the measuring probe (e.g. a vertical gradiometer) into the plastic pipe. The measurement data obtained in this way is later evaluated by specialists on the computer. Depending on the result, the ground is then either released, or further necessary measures are taken if required.

If there are indications of old mining activities, exploratory drilling is carried out immediately, provided that contamination with explosive ordnance can be ruled out. In this case, boreholes are also drilled in a defined grid using a flushing drilling method. Contrary to explosive ordnance exploration, this can also be carried out using the percussive drilling method, if the subsurface requires it.  Hits, or rather tapped cavities, are recognized by the drilling specialists either by the sagging of the drill string or by the drying up of the mud flow. The size, location and course of the cavities are then determined and mapped by further drilling in the vicinity of a hit. If necessary, a plastic pipe is also inserted into these boreholes, through which the cavity is backfilled with cementitious building materials after the drilling work is completed. "A few thousand cubic meters of fill material can accumulate on a construction site," reports T. Hölscher. Depending on the intended later use, additional injection boreholes may be drilled to inject grout for further stabilization of the foundation soil via sleeve pipes.

The construction site on Hachestraße is located in the direct neighborhood to the shafts of 3 historic underground coal mines :

• Mine "Secretarius Aak" – mining about 1750 to 1805 in 50 m distance
• Mine "Vereinigte Hoffnung und Sect. Aak“ shaft “Hoffnung" – mining activities from 1805 to 1897 in 150 m distance
• Mine "Vereinigte Hoffnung und Sect. Aak“ ventilation shaft in seam “Röttgersbank" in 40 m distance

Already during construction works on Hachestraße in 2013, cavities were discovered that can be assigned to the former mine field of the "Vereinigte Hoffnung und Sect. Aak" colliery. After exploratory drilling, extensive backfilling work was already necessary at that time[iv]. It can therefore be assumed that test drillings will also be carried out at the current construction site as soon as the exploration for explosive ordnance has been completed.

The KR 801-3GS used here defines its own class of especially compact and, at the same time, universally applicable drilling rigs. Mounted on oscillating tracks, the drilling rig is ideal for almost all jobs encountered in special civil engineering – from light to heavy drilling works. Equipped as standard with a power-optimized hydraulic system (KLEMM "Power Sharing"), the Energy Efficiency Package (KLEMM "EEP"), adaptive rpm control of the engine and fan, and effective sound insulation hoods, the unit, with its low emission values is also ideally suited for inner-city use. The ergonomic design, easily maintainable, fail-safe machine control with remote diagnostics, remote control operation, and extensive safety features round off the package.

Despite the modern machines and processes available today, the search for, and removal of, the relics of war and mining will remain an eternal task for many generations to come on the Rhine and Ruhr.

Wikipedia: list of mines in North Rhine Westphalia (https://de.wikipedia.org/…)

[ii] div. publications of the district government Arnsberg
(https://www.bra.nrw.de/…)

[iii] Press release from the state NRW
(https://www.land.nrw/…)

[iv] Report on „derwesten.de“ dated 27.11.2013
(https://www.derwesten.de/…)