每日吃瓜

So dim and grim has been the scenario of foundation equipment market in India, one may find it hard to digest the fact that only on account of depreciated value of INR against USD/Euro during the last couple of years the equipment cost has gone up by 20 per cent, which amounts to an increase of price by Rs 60 lakh to 2.5 crore, for different models. And that too, at a time when the whole infrastructure sector has been paralysed due to various reasons. Says DV Brahme, Regional Manager, Mait India, "On the macro level, other than metro rail projects, there are not many new projects. In many cases, the proposed investment is on hold or the projects are held up for reasons such as funding, land acquisition or statutory clearances. And on the micro level, individual equipment owners are finding it difficult to get projects and realise payments in reasonable time for work already done." To add salt to the injury, finance companies are not willing to fund the small companies or individual buyers and big companies stopped purchase of capital equipment unless. Brahme adds, "Shortage of big projects has led to the fall in rental prices due to which the break-even is getting delayed and further investment in rental segment has stopped."

Advancements in rig technology
The piling industry is responding by developing different types of piling, piling design and geo-technical solutions to ensure sustainability, innovation, cost effectiveness. In a highly competitive space, differentiation has been playing a key role and most of the OEMs have introduced latest technologies in India be it continuous flight auger (CFA), continuous helical displacement piles (CHDP), large diameter augur (LDA) or resonance-free vibratory hammers.

"Hydraulic rotary rigs have been a boon to the industry. All these new generation rigs have monitoring facilities. A project can be executed faster and overall cost can be optimised by using these advanced rigs," says Dr PV Chandramohan, President Technical, Navayuga Engineering Company.

"Rotary piling rigs are the latest iteration in piling rigs," avers Sunil A Borade, Partner, Stefon Constructions, which regularly uses a mix of imported rigs from Mait (HR130 and HR180) and conventional rigs fabricated by Stefon, the Mumbai-based foundation specialist firm.

According to Rakesh Kailash Singh, Joint General Manager Construction, Plant and Equipment Division, Afcons Infrastructure, integrated piling rigs are in vogue as these are very cost-effective. He says, "Integrated piling rigs are very cost-effective over conventional rigs with respect to the factors such as increase in productivity, decrease in man power cost, execution of job in very short span of time, and due to heavy torque, penetration in hard strata has become easier."

Singh further adds, "Our rigs procured in initial fleet were equipped with depth measuring device. In addition to this, nowadays we are getting new generation rigs equipped with emergency mode of operation for drilling rig (core functions), mast inclination measurement on X/Y axis (both digital and analog display), automatic vertical alignment of mast, and hydraulic load sensing on auxiliary rope, etc." Says Brahme, "The big advantage of rotary displacement piles is that nothing is removed from the ground, so there is no effort or resource and eventually cost for disposal of muck. Because of the displacement of the soil and addition of concrete, the overall consolidation of ground (increased density) takes place more than in bored piles." He adds, "At progressive companies like MAIT, product development is a continuous process. We always try to incorporate the latest technology developments in our rigs and pass on its benefits to our clients. Of course, we do not indiscriminately run after new technology or components but only after extensive testing of such components and confirmation of suitability of such items for our product as well as value addition and long term benefit for our clients we incorporate them in our rigs." He adds, "In MAIT rigs, there is a built-in patented automatic levelling system for ensuring the verticality of bored piles as well as diaphragm walls. In MAIT diaphragm wall rigs, advanced monitoring system to see verticality with respect to X, Y and Z axes can also be fixed if needed. MAIT rigs can also be used for raker / inclined piles up to 200."

Advancements in hammers
Highlighting the advancements in the vibratory hammer technology, Surajit Mukherjee, Managing Director, Suretech Infrastructure says, "The latest advancement in vibratory hammer technology is the use of resonance-free vibratory hammers, which can work in city centres to drive sheet piles with casings noiselessly. This avoids bad vibrations to surrounding buildings, monuments, etc. It is ideal for metro projects. He adds, "The latest models of power packs of ICE vibratory hammers are equipped with variable displacement pumps. These pumps will sense the soil resistance and deliver the appropriate hydraulic flow to the hammer. It will result in less hydraulic power of the power pack and thereby reducing the fuel consumption."

According to Mukherjee, the latest foundation technology trend is driving the casing with ICE vibratory hammer and then drilling through rock with the use of BUMA reverse circulation drilling rig. He further adds, "ICE power packs are designed as an open loop system, which will have easy troubleshooting and latest technology, iQan system, CPU unit to control the power pack, and emergency switches on the power pack canopy that can be easily accessed by the operator."

Flexibility, the new mantra
Given the prevailing slowdown and its impact on the contracting fraternity, flexibility is emerging as the new mantra when it comes to advanced rigs. Flexibility of a rig to suit different application by changing the tool kit has become very important as it can cut down expenditure considerably. It eliminates the need to buy different rigs as a tool kit from the same OEM or of a different make can be fit to the existing rig. According to Singh of Afcons, one of the important factors while purchasing a rig is to find its versatility to execute different kinds of jobs (flexibility of the rig). Says Brahme, "MAIT rigs are versatile equipment and can be used for bored piles, CFA piles as well as diaphragm walls by simple change of a kit. Changing from bored piles to diaphragm walls version and vice versa can be easily done at site and takes only 4-5 hour time. In addition, the client saves on the cost of buying two equipment for bored piles and diaphragm walls. If one has a MAIT rig in bored piles version, the CFA or diaphragm wall kit can be procured and mounted at a later date ? say a few years later. There is no need to buy all the kits initially and block the capital." He adds, "We also have a low head room (LHR) series of piling rigs that can work under low roofs, inside the existing buildings, structures, basements, etc. MAIT rigs are designed to work in extreme weather conditions like that of extreme high temperatures in the Middle East to extreme cold conditions in Siberia. Our rigs have worked at very high altitude in the Tibet railway project and in various marine piling projects in rough sea conditions. MAIT rigs have practically worked in all these conditions."

Says Ghananeel Molankar, Sales Manager, Liebherr India, "The Liebherr foundation equipment can perform a wide range of applications with a high level of precision due to its superior control systems. Also features like PDE, PDR and LiDAT give us an edge over the competition." LiDAT is a data transmission and positioning system for Liebherr machines and the other machine manufacturers. Based on state-of-the-art technology, LiDAT provides information on the location and operation of your machines, enabling their efficient management, optimal operation scheduling and remote supervision.

Cost efficiency
While a conventional rig cost you Rs 10 to 20 lakh, the cost of an advanced rig is around Rs 4-5 crore! So is it really worth paying a bomb for such a piece of machine? Does it really pay back? High initial investment has always been a deterrent in adopting advanced technology. However, over the years, concept of life cycle costing is gaining ground and more end-user segments have started appreciating this. What they are looking at is quality and productivity on a long term that could help them, to say the least, to sustain the profit margin, or could even better it. Says Singh of Afcons, "Initial cost difference is definitely substantially higher. However, based on production and quality of job executed, we can compensate this difference to a large extent."

Borade of Stefon explains it further. "Advanced rigs give 10 times better productivity than conventional ones. The real cost-effectiveness of the advanced rigs is realised on medium to big size piling jobs. We can dig deeper and faster, which also aids in the overall cost effectiveness of these rigs." He says, "Good work progress and better output can be achieved with advanced rigs. For our Mait rig, we just need one trained operator, and 3-4 skilled workers. In cost terms, one conventional rig costs maximum Rs 10 lakh while the MAIT rig costs Rs 4-5 crore. But in operational costs, MAIT rigs give better productivity, and saving in labour costs and maintenance costs. One MAIT rig is equivalent to 10 conventional rigs. Each conventional rig needs at least seven workers. For 10 such rigs we require 70 workers. But in the case of MAIT rig, we require only four skilled workers. So, we have a huge saving in excess labour and overall operational costs. Also, we can work in limited space with maximum output which is a necessity in city limits where space is a constraint."

Of course, there is a word of caution. Says Amitesh Ranjan, Deputy General Manager, Gammon India, "In piling rigs, the cost difference between a conventional one and a hydraulic one is huge. But using an advanced rig in place of a hydraulic rig is not that much effective. For an advanced rig, you require well-qualified operators and need to pay more. Maintenance of such machines is very difficult due to non-availability of parts and trained people to repair. If an advanced machine gives 20 per cent more productivity and once it is broken down, you have to wait for a long time for an engineer to come from outside to attend the problem. It is time consuming and the machine will be idle for a long time."

Selection of piles: Bored vs driven piles
Compared to bored piles, which are most popular in India, driven piles are faster and more cost effective. However, its use has been very limited. In India, we focus more on bored piles and driven piles are not accepted except for some cases like Paradip Refinery and industrial projects in Hazira. According to Brahme, bored piles is the most popular deep foundation method due to its suitability in almost all soil conditions, and possibility of making big diameter and going to a very long length (depth), whereas the application of driven piles is limited to loose soil area. He says "Due to the high energy requirement for driving of piles, the diameter or cross section is limited to 600 to 700 mm and also the depth. Moreover, driven piles cause a lot of vibration and therefore cannot be used in areas with dense construction like cities. Of course, they are much faster to drive, but its application is dependent on finding the suitable soil strata therefore they are not much preferred by the end-users." He further adds, "Since there is a lot of availability of bored piling rigs, the end-users also prefer to use the same system to keep the project cost low since the contractors do not need to specifically buy new equipment for their projects. However, we believe that there will be some more growth of driven piles in India in the time to come."

Explaining the pros and cons of driven piles, Molankar says, "Precast driven piles can be produced to almost any required length and cross-sectional form. They have a high load bearing capacity. Also, the load bearing capacity of the soil is increased due to the compaction of the soil during impact driving. They are ready to take loads immediately after installation. Driven piles can even withstand seawater." However, he cautions about the disadvantages of driven piles. He adds, "Precast driven piles have to be manufactured in full length or in sections at a precast yard and then transported to the job site, which involves transportation cost. It is seldom that the driven piles are precast on the job site. Precast driven piles require great care and attention during transportation and during set up of impact driving. Incorrect handling can cause cracks on the pile. These piles are very sensitive to bending. Vibrations and noise are generated during impacting. There is a high risk of buckling if an obstruction is encountered during impact driving. Once an obstruction is found, then it is almost impossible to remove the obstruction."

Mukherjee takes a different angle to it. According to him, the limited use of driven piles is due the outdated codes and specs. He says, "The use of driven piles even though is faster and more cost effective, its use has been limited due to outdated codes. All equipment such as ICE vibratory hammers, BSP impact hammers, IHC hydro hammers and IHC Fundex rigs required for driven piling are available in India. The best examples are IOCL project at Paradip, where Kazstroy and Valecha completed the project using the above equipment, in which the concrete and reinforcement were readily available and a record of 35 piles were driven in two shift operation.

He further adds, "Driven piles world over are to be driven to the point of refusal. The point of refusal for ICE vibro hammers is a minimum penetration of 250 mm in five minute and for BSP impact hammers is a minimum penetration of 10 blows/25 mm. However, the consultants in India want the piles to be driven to a predetermined level, even if the refusal is already achieved. We are still educating the clients on this process."

Borade had this to say. "In our opinion, the notion that one method of piling is superior to the other is wrong. Type of piling is decided on the basis of site geology, depth requirements, pile geometry, etc. In places like Mumbai where good quality rock is generally available across the region, and piles are designed as end-bearing piles, driven piles may not be a feasible option. However, in places like Kolkata or Gujarat where piles are mostly designed as friction piles and rock is available (if at all) at very great depths, driven piling is suitable." He adds, "The ease of availability of equipment, spares, and relative ease (where driven piles can be done, rotary piles can also be done but not vice versa) has today led to the piling industry orienting itself towards rotary piling. Therefore, you are right when you say that cost and lack of advanced equipment may be a deterring factor. However, sufficient expertise is available in the country and specifications, codes, etc. are also there."

"We have to design a pile that can be executed. At NEC we have even made upto 2.5 diameter piles. High rise structures need very small diameter piles whereas we require large diameter piles where the horizontal impact is high like in a bridge or jetties, and bored piles are a better option, says Dr Chandramohan.

Trends in metro projects
Even during these troubled times, it is the metro projects that gave some sustenance to foundation equipment segment. 每日吃瓜 tried to find out the trends that have been used in these projects, especially the adoption of diaphragm wall over secant piles. According to Brahme, so far for elevated viaducts, bored piles are being used and for underground routes diaphragm walls are used at the stations. He says, "Diaphragm wall gives a smooth surface as well as continuous wall while secant piles do not give smooth surface. Due to the full size reinforcement cages, the diaphragm walls are believed to be stronger and have uniform strength throughout the length. Compared to secant piles wherein every alternate pile, which is called primary pile has a reinforcement case, while the piles in between two primary piles, which are called secondary piles, do not have reinforcement. So the secant piles wall does not have uniform strength throughout the length. Compared to the diaphragm walls, making secant piles needs more skill and effort in maintaining the verticality and alignment." Says Molankar, "We have seen a wide use of slurry/diaphragm walls in metro projects in India. Liebherr Werk Nenzing offers HS series heavy duty cycle crawler cranes with diaphragm wall grabs. Diaphragm wall grabs are of two types mechanically and hydraulically operated. Liebherr offers 10 models in HS series crawler cranes ranging from 30T to 300T capacity. These cranes are designed for heavy duty cycle applications like clamshell, dynamic soil compaction, casing oscillators, slurry/diaphragm wall grabs, trench cutters, carrier for piling and drilling rigs." Molankar further adds, "The width of the grabs that we offer range from 600 mm to 1,500 mm and length of the grabs range from 3.2 m to 4.2 m. The hydraulic slurry wall grabs are equipped with a permanent measuring and control system, which makes it possible to recognise any deviation of the vertical excavating direction immediately and to indicate it to the control panel of the operator. This deviation can be corrected with the help of modifying the direction of the grab. Thus, high accuracy is obtained at deeper depths also of more than 50 m. These grabs are also equipped with a deviation control system for the X and Y axis, as well as with a rotation control including data read out and monitoring system. The mechanical slurry wall grabs that we offer can also be controlled verticality."

According to Mukherjee, the use of resonance-free vibratory hammers is the most ideal tool for metro projects as this technology can be used to drive sheet piles with casings noiselessly without vibrations to surrounding buildings. However, so far, this technology has not been used in any of the metro projects due to the initial high cost and lack of awareness (See box on ICE Resonance-Free Vibratory Hammers).

Selecting a rig
Delivering cost-effective solutions in reasonable time frames was and remains one of the major challenges for ground engineering professionals. One of the major challenges is the nature of the soil strata. For soft soil, the production can be more and if it is hard rock, the progress of the job will be low. So the selection of the piles and installation equipments become more important. According to Borade, selection criteria depend on the diameter of the piles which normally ranges from 500 mm to 2,500 mm.

Singh says, "Selection criteria are based on many points. Some of the major factors are geo-technical data, quantum of work, time frame in which the job needs to be executed, past performance, and quality of work needed." He adds, "While buying a new rig, we focus on the productivity of the rig, its cost, availability of spares and service support, versatility to execute different kind of jobs (flexibility of the rig), reduced time for repairs as the cutting tools are interchangeable and no machining is required.

Shortage of skilled operators
Availability of trained and skilled operators is a major challenge. According to Borade, piling being a very hands-on sort of a job, mostly experience is gained by people once they start working on the field. So, the acquisition of skills is totally dependent on the number of hours one has spent in the field. A person with around five years of field experience is a great asset for any piling company.

Brahme had this to say, "Continuous training is the only way to address the skill and knowledge level required in the field. As an equipment manufacturer, MAIT conducts various training programmes for the operators and mechanics of its clients for safe operation and periodic maintenance of the rigs. We believe that piling companies must also keep conducting trainings for their staff for efficient execution of the projects. On the individual level, every related person must strive hard to upgrade his own skill and knowledge which will ultimately help the industry at large."

Opportunities
The growth of this segment closely related to growth of infrastructure projects such as power (thermal/wind/ hydro and nuclear) high rise structures and metros. The ambitious plan by the new government to develop Diamond Quadrilateral Project of high speed trains, networking freight corridors, development of ports and inland and coastal waterways, creation of 100 smart cities are sure to give the much-needed boost to this segment. Says Brahme "There are huge expectations from the new government in all spheres of life, specifically in the infrastructure development. Ever since the new government has assumed charge, the enquiry level has gone up and many companies are preparing for expected growth in infrastructure development." Surajit sums up with a positive note. "Compared to the last couple of years, we hope the market situation for foundation equipment segment to improve. With the new government, we hope that many projects, which were kept on hold because of funding, land acquisition or statutory clearances, are given the green signal."

SELECTION CRITERIA
Based on project: 

• Geotechnical data
• Quantum of work
• Time frame in which the job needs to be executed
• Past performance
• Quality of work needed

While buying:

• Productivity of rig
• Cost of rig
• Availability of spares and service support
• Versatility to execute different kind of jobs
• Reduced time for repairs as the cutting tools are interchangeable and no machining is required.

IMPROVING THE PERFORMANCE

• Proper planning to avoid idling of machine.
• Operating crew must be equipped with good knowledge about machine and the job.
• Use of spares and cutting tools recommended by OEM.
• The maintenance schedule of machine recommended by OEM must be followed religiously.
• Proper monitoring of productivity to check the actual work with respect to the plan.

THE RUPEE IMPACT
Equipment cost has gone up by 20 per cent which amounts to an increase of price by Rs 60 lakh to 2.5 crore, for different models.

ICE Resonance-Free Vibratory Hammers
Resonance-free vibro hammers can work next to even dilapidated structures without causing any damage. The advantage of resonance-free vibratory hammers is that these do not pass bad or harmful vibrations to the surroundings and thus can work in city centres and congested areas.

Says Surajit Mukherjee, Managing Director, Suretech Infrastructure, "Conventional vibro hammers have a constant eccentric moment. When passing the critical frequency area during start-up and stop, the constant amplitude will cause disturbing negative vibrations in the boom of the crane and in the soil; not just at the spot, but with a considerable perimeter distance. When using a resonance-free vibratory hammer with an adjustable frequency of 0 to maximum 2,350 revolutions per minute, critical vibrations in start-up and stop are eliminated. After passing the critical frequency area, the eccentric weights are automatically adjusted and synchronised to the current eccentric moment."

How it works
During the start-up of the vibratory hammer to the maximum frequency of 2,350 revolutions per minute, the eccentric moment is '0'. The eccentric weights cancel each other out and no vibrations (amplitude) are generated. When reaching the maximum frequency, the automatic adjustment of the eccentric weights takes place, the so-called 'in moment' amplitude. As the vibro hammer already reached its maximum frequency, there is no question of passing a critical frequency. Disturbing vibrations during start-up and stop are eliminated.

The adjustment of the eccentric weights is completely automated. As manual (remote) control for shifting the eccentric weights is possible, the most ideal amplitude can be generated for each soil type. Mukherjee says, "It is not necessary to readjust the vibro hammer when stopped and re-started. The hammer will automatically select the last setting. With RF, it is possible to maintain the hammer at its maximum frequency while bringing the eccentric moment to 0. The hammer can be brought to standstill without causing any vibrations."

Suretech Infrastructure, which has supplied nearly 200 machines to Indian customers, is the authorised dealer of ICE - Holland, Netherlands (Dieseko Group BV) for their wide range of hydraulic vibratory hammers, resonance-free vibratory hammers, excavator-mounted vibratory hammers, earth augers and submersible dredge pumps.

ADVANCED FEATRES
Features in-built and optional to improve and optimise the O&M cost in Mait rigs

• Single-layered winch with perfectly grooved drum ? increases the life of wire rope.
• The big and heavy winch drum gives additional stability to the rig.
• Patented automatic levelling system ensures perfect verticality of bore and operator comfort.
• Use of Teflon pulleys reduce friction with the wire ropes and enhance its life.
• Large capacity hydraulic tank ensures rapid cooling of oil and enhances the life of components as well as rubber items like seals, O-rings, flexible hoses.
• Use of quick coupling with lock valves ensure minimum oil spill in case of hose failure.
• Simple hydraulic circuit and use of electricals for control ensures easy trouble shooting and faster rectification of troubles.
• Versatility of the equipment for use in bored piles, diaphragm walls, CFA piles and other foundation techniques help the clients in avoiding purchase of separate equipment for different techniques.

Machine-control and monitoring technologies

• The engines are computer controlled and all the engine parameters are electronically monitored.
• In case of abnormality, the engine is automatically shut down to avoid any damage or accident.
• No hydraulic operation takes place unless the operator is properly seated in his seat.
• There are lock valves placed in the supply lines of mast cylinder to avoid accidental folding of
• Mast in case of hose failure. The similar system is provided in all the hydraulic cylinders.
• End of stroke switched are provided for Kelly bar and 2nd winch to avoid accident.
• Rotary end of run switch is fitted to keep rotary in particular position during folding of the mast to avoid any imbalance.
• Safety lock has been given for winch during transport mode.
• The operator cabin has fall over protection system for safety of operator in case of big and heavy object falling on the cabin.
• Emergency shut off switched are given in the operator cabin as well as on the back side of the rig.
• Operator's cabin is air conditioned with facility of adjusting seat height, microphone to communicate with outside persons.
• In bigger models rear view cameras are provided to see the area behind while moving backwards.

CASE Study
Project: L&T Petronet. Driving casings of 1,000 mm dia up to a depth of 11 m. Total number of casings to be driven is 1,272.
Type of construction: Storage tank
Project execution: Keller Ground Engineering India
Machine used: Vibratory hammer model ICE 416L.
Why ICE Holland: ICE Holland (Dieseko Group BV, Netherlands) is not only the largest supplier of vibratory hammers in the world but by far the largest in India and is India's most preferred brand for the high level of product support in after sales services from Suretech, who is the sole distributor of ICE-Holland for the Indian sub-continent.
Challenges: Soil very bad and tough to drive the casings.
Equipment performance: The vibratory hammer was driving the casings very smoothly at a frequency of 1,600 vpm. The average time to drive a casing upto a depth of 11 m was 10 minute.

Techno-commercial benefits:

• High production rate
• Low fuel consumption