BAUER Maschinen GmbH, designs and builds rotary drilling rigs, diaphragm wall devices and all tools, has been operating independently within the BAUER Group since 2001. Bauer machines for special foundation engineering have stood for highest performance and quality since the end of the sixties, for ongoing innovation. Bauer Maschinen offers “more than just the machine” – the extensive experience gives the customer complete solutions from a single source.
Construction Review conducted an interview with Ruediger W. Gerarts of NorthRhine Consulting Limited, Nairobi, Kenya, Official Sales Representative of BAUER Maschinen GmbH on modern drilling technology.
What are the new technologies with regards to drilling equipment?
Maybe we should not talk about new technologies, but about well proven equipment, needed in the African markets. The most current technologies are nice to have, but right now not always needed. Big drilling rig manufacturers like BAUER are currently working on autonomous drilling machines, that can in theory be operated out of everybody office or home. An insight in the current development status was shown recently during the BAUER In house exhibition. Despite there’s a huge span of drilling methods like CFA, CCFA, FDP, FOW etc. the main used method for doing piling is Kelly drilling and can do most of the jobs in Africa for now
With the use of standard equipment for piling you will at least make sure, that in some cases your building will not collapse during heavy rain, in case it has been built next to a river on soil using a raft foundation. The wet soil will not withstand the heavy load of the building. Piling will ensure the stability of the foundation.
Or consider the excavation for a building has been done, maybe 15 m to 20 m below ground level, to allow parking of cars. Usually you have at least a layer of soil on top of the surrounding area. During heavy rain this layer might slide in the excavated area, hopefully not burry some workers. Even a wall with bricks along the soil might not withstand the pressure caused by extremely wet soil or mud. Do not forget, that the contractors will build the slopes are as vertical as possible to reduce the excavation cost. Usage of the right equipment to build an anchored secant piled wall (shoring) might eliminate that risk.
Your case is different? In your pit the walls are solid rock instead of soft soil? You think this will not collapse? Maybe you are right. You have not thought about the cracks you saw some days ago, several meters long? Unfortunately you are not able to look inside the cracks to check the details. In this case large blocks of rock might fall out the wall. Do not forget to the loads of surrounding buildings and vibrations during ongoing works. In this cases you can use back anchoring equipment to hold them in position.
How have they been received in Africa?
This depends on the areas in Africa. A strong growth in population often leads to urbanization and thus to a development of fast growing cities. The demand for real estate housing and expanding infrastructure in central city areas pushes the needs for high rise buildings and bridges in a reasonable time frame. When time becomes a factor, single pass drilling methods are more and more used when possible.
For example in Egypt and South Africa is quite a big number of machines in the market available that can perform Kelly, CFA and FDP Drilling. In other areas of Africa, we even don’t find this type of equipment in some countries, meaning the contractors have to find other contractors in neighbouring countries. Mobilisation of the equipment from another country to operate for a specific project is expensive. In most cases it is more than just a load for a standard truck, since the weight of the equipment is very high.
Furthermore we made the experience that obviously some consultants stick to the old fashioned, but well proven designs of foundations. The reasons might be they might have not been trained well for the foundations techniques concerning piling or they just hesitate to use them due to lack of experience. When you compare the cost between raft foundations and piling foundations you will find out that the cost for the required concrete and the rebar used in very thick raft foundations is higher than the use of drilling equipment for piling with a relative small amount of concrete. The relation of cost between raft foundation and piling depends of course on the size of the building and the geotechnical conditions of the soil and rock.
What are the factors to consider when selecting a drilling equipment?
Of course this depends on the type of drilling. Speaking in layman’s terms, the main parameters that define the drilling equipment are the final diameter, depth and ground conditions. Piling for a tall building like The Pinnacle in Nairobi requires completely different equipment compared to back anchoring, shoring or sheet piling. Furthermore the soil conditions and hardness of rock might require different tools for the drilling.
Since our customers usually will not buy the equipment for one project, it is important to check the general requirements to be able to execute most of the jobs you expect in future. Buying equipment a bit stronger than required for the next project will be more expensive now, but give you more possibilities for other projects in future. Hence please discuss about your needs with the specialists. It is always good to talk to several people before making a final decision.
As a general recommendation we advise to think about the cost on a long term basis. You think cheap new equipment is really cheap? In case you consider the investment cost only, you might be right. But think about the life time of the equipment and the maintenance cost. Maybe you are aware, that some brands of cars are cheap to buy, but you have to buy a lot of spare parts in future, the life time of the car will be short. At the end, you, the customer, will not be happy, both with your car and the drilling equipment
What are the proper steps to consider with regards to drilling equipment maintenance?
You should follow the recommendations of the manufacturer as written in the documentation, both for regular inspections, whether daily, weekly or longer intervals, and the regular replacement of some parts, as for example oil. This means you should treat your machine similar to your new car, to avoid a major damage, involving a lot of money to do a repair. Make sure you buy genuine spare parts with the same quality as originally used in the machine. Avoid sources of spare parts with quality you should have doubts, just because the are very,very cheap. Fake parts, too cheap to be a genuine parts. Please consider that you might not only damage the machine and reduce the performance with the cheap spare parts, but depending on the type of parts risk the life of the operators working with the equipment as well. Most company like BAUER offer a 24/7 technical hotline to assist the client with all his questions about the product and also trains the clients staff to get familiar with maintenance.