As a leading geotechnical specialist contractor, how do you see the civil construction industry evolving with respect to cutting-edge technologies, quality, R&D, and best practices?
The infrastructure industry is highly responsible for driving India’s overall development and enjoys intense focus from the Government for initiating policies that would ensure the country’s time-bound creation of world-class infrastructure, and economic growth thereby.
While India is focusing on its growth plans, it is imperative that the country should also analyze, and have a comprehensive plan for, sustainable construction. It must take into consideration parameters like material and energy conservation, and recycling of waste/demolished material to help build a world that will improve the lives of future generations.
There is a perception that sustainable construction is expensive, and may appear to be financially unviable, but the long- term benefits will save our natural resources and developing more affordable solutions. There is good progress being made on usage of recycled concrete debris, brickbats, fly ash, manufactured sand in construction. However, the Indian concrete industry needs to focus on how we reuse concrete or use fly ash mixed in concrete to reduce CO2 emissions, which will lead to sustainable utilization of concrete.
The industry is anticipating an acceleration in digital transformation with most of the construction companies in India considering going digital or are at the early stages of digitalization. These companies are quickly learning the best practices from their peers in developed markets.
What are the various challenges in the construction of deep foundations in India with respect to project type, size, and site condition?
Infrastructure development in India is seeing rapid construction of roads, new refineries, port and harbours, and industrial facilities. However, in terms of land use, not every land is suitable for every major structure due to the varying topography and soil stratification. Open and almost vertical cuts are required due to space constraints in underground constructions. Urban development thereby becomes challenging due to the surcharge of adjacent structures.
The major challenge is the high risk involved during construction due to the presence of weak soil stratum, and high ground water table, resulting in the requirement for foundations designed in these strata. Such construction requires skilled workmanship, special equipment, construction methodology, accuracy, and safety measures as any lapse will reduce efficiency and productivity.
Inadequate geotechnical investigation has been experienced in many civil engineering projects in India for saving time or cost. What is your take on this and its impact on the structures?
Insufficient or inadequate geotechnical data bring risk to projects, unsafe design of foundations, construction delays, as well as extra costs. Design of foundations for their service life is based on the geotechnical investigation. Inadequate geotechnical investigation data is mainly due to a lack of client awareness on the impact of construction quality or due to unavailability of an expert to stress the importance of this work for design of foundations. Thus, it is very important to have a clear, concise, and accurate geotechnical investigation report reviewed by qualified geotechnical engineers to ensure the reliability of the investigation results. And lastly, it’s wise to spend time and money in the early stages of a project on geotechnical investigation rather than ending up with a higher cost and construction delays in the long run.
How important is geotechnical investigation for selecting a suitable foundation solution, considering site condition, geology, and size of projects?
When we think of construction work, we often picture the construction site or even the completed project. People tend to forget the planning, investigations, and foundation work that take place onsite even before a brick is laid.
Detailed, accurate, and reliable soil investigation data is very important for optimal foundation solutions (piling or ground improvement solution or open foundation). This data helps not only in arriving at design parameters but also in the finalization of construction methodologies. Major operational aspects such as rig capacity, depth requirements, hammer capacity (in case of driven piles), installation rate, selection of stabilizing fluid, and the materials to be used in the foundation (type of cement and steel) can be decided well in advance if we have sufficient and consistent soil investigation data. It is always suggested to use the advance soil investigation methodologies for subsoil characterization.
What are the challenges in design and construction of foundation in non- liquefiable and liquefiable soil?
The Indian subcontinent is one of the most earthquake vulnerable countries in the world due to the ongoing convergence between the Indian plate and the Eurasian plate. Geotechnically, the major concern is to address or mitigate liquefaction potential of the subsoils in the event of an earthquake. Saturated cohesionless sands and silts develop high pore water pressures which causes liquefaction in the event of strong ground shaking. The rise in pore water pressures results in significant degradation of strength and stiffness. If soil liquefies, it results in permanent deformation in the form of lateral spreading or flow failure, and/ or vertical settlement.
With the advancement in technologies, the structures can be supported on open foundation with ground improvement techniques like vibro stone columns, vibro sand columns and vibro compaction. These techniques mitigate liquefaction potential of subsoil and also increase the bearing of the underlying soil stratum.
In cases where the structure demands a foundation solution as piles, the design of pile foundation has some challenges that require advanced analysis by geotechnical engineers. The design requires careful consideration in terms of assessment of behaviour of the piles and the impact on the supported structures in the event of an earthquake. During intense ground shaking, soil imposes a cyclic load on piles due to transient movement, whether liquefaction occurs or not. During this shaking phase, the pile is prone to severe cracking or even fracture. In addition, these permanent deformation impacts the load carrying capacity of the pile.
Liquefaction also leads to substantial increases in pile cap displacements above those for the non-liquefied case. The soil deformations can exert severe pressures against the piles, leading to failure. Such failures were prevalent in Japan during the 1964 Niigata and the 1995 Kobe earthquakes. Lateral spreading is particularly damaging if a non-liquefied layer rides on top of the liquefied soil.
It is only in the last few years that the profession has begun to deal effectively with these critical design issues. The progress in analysis has also allowed more fundamental and comprehensive evaluations of case histories, leading to a greater appreciation of design problems. The pile design in non- liquefiable soils is also not straight forward, specifically when there is very soft soil or there is recent filled up soil, which imposes additional load on piles and results in downward drag (negative skin friction) of piles, demanding to go for deeper pile depth and requirement of temporary casings.
Keller being a specialist in this area are actively involved in research related to earthquake engineering. We are working with owners and their geotechnical engineers to arrive at an optimal foundation solution. Keller India in the last 20 years executed more than 125 projects in highly seismic regions across the Indian subcontinent and provided foundation solutions.
What are the unique techniques and solutions provided by Keller India that are quicker, cost-effective, and environmental-friendly?
Keller India provides solutions for a wide range of geotechnical challenges across the entire construction sector through single or a combination of various techniques and foundation works. Uniquely, Keller offers global strength and local focus. Our knowledge of local markets and ground conditions makes us ideally placed to understand and respond to a particular local engineering challenge. Our global knowledge base then allows us to tap into a wealth of experience, and the best minds in the industry to find the optimum foundation solution.
We offer solutions to address the geotechnical problems such as bearing capacity enhancement, mitigation of liquefaction potential, shoring and earth retention, settlement control, ground water control, and near shore marine construction. “Building the foundations for a sustainable future” is at the heart of everything we do. Keller India, in line with Keller Group’s vision, structured its approach for ESG and Sustainability according to the 4P’s - Planet, People, Principles and Profitable Projects – and aligned our sustainability strategy with the United Nations Sustainable Development Goals (SDGs).
Importantly, in respect of carbon reduction, we have set ambitious and achievable net zero targets by 2050 (Ref: Carbon reduction | Keller Group plc). We divide our emission targets using the scopes set out in the Greenhouse Gas Protocol. We have started the journey to implement the short, medium, and long-term actions required to achieve these goals.
What are your innovative techniques for creating sustainable foundation for application areas which are prone to earthquakes?
Sustainability in the field of construction practices consists of three pillars: economic, environmental, and social. In geotechnical engineering, there are two primary approaches for sustainability application, either the replacement of materials or the modification of a design in order to improve the economic, environmental, and social impact of the project. For example, use of vibro stone columns or vibro compaction as an alternative to heavy foundations for suitable projects results in reduced carbon emissions as the usage of steel and cement is eliminated.
In earthquake prone areas, providing drainage path using vibro stone columns is the key mechanism instead of using heavy foundations. Also, the design of pile foundations might require heavy reinforcement to cater to high seismic loads. In such areas, adopting to an innovative and sustainable foundation solution like ground improvement using deep vibro techniques rather than conventional pile foundation will give savings in terms of economy and construction resources, while satisfying the required technical performance. These techniques are cost effective and are sustainable as very less usage of processed materials is there to improve the in-situ soil’s properties. Other techniques like deep soil mixing, wet soil mixing, and jet grouting are also a part of our expertise in providing sustainable foundation for earthquake prone areas.
What are the codes, standards, and guidelines in India for design, installation, construction, and testing of foundation and excavations?
In India, IS 2911 and IRC 78 are widely used for the design, construction, and testing of different types of pile like bored piles and driven piles. For ground improvement methods IS 15284 is widely referred. These codes provide details about the construction methodologies, quality control measures and checks, testing frequency and guidance on how to design ground improvement & pile foundations. However, other latest advancements like continuous flight auger piles (CFA) advancements in the design of piles and ground improvements methods can be included in Indian standards which will benefit the construction industry. Efforts are being made to bring the changes required in the codes with the help of various committees formed to review and suggest changes under various forums (like DFI-I / IGC) and BIS committees.
What, according to you, are the right practices for Quality Control (QC)/Quality Assurance(QA) of deep foundation testing?
The QA-QC of deep foundations are much more difficult than QA-QC of other construction visible elements because any potential defects are well buried deep in the ground. Early prevention of problems is the most effective means to avoid costly and time-consuming construction delays.
During the construction process, the pile may have defects such as diameter reduction, diameter expansion, mud inclusion, segregation, and broken piles. The existence of pile body defects will change the normal working behavior of the foundation pile, thereby causing potential danger to the foundation.
The use of non-destructive testing, combined with full-scale load testing, act as a right tool for ensuring the QA/QC aspects of deep foundation testing. Deep foundation testing includes low strain integrity testing, cross hole sonic logging and pile load tests. Experienced staff performing the tests and accurately assessing the deep foundations of a project are key to reduce delays and complications that could become expensive in both cost and reputation.
Usage of right testing techniques are the key to effective quality control. “low strain pile integrity test” provides a cost- effective tool for assessing major voids and defects; however, it becomes less effective for longer shafts. We could use methods such as cross-hole sonic in such cases to assess concrete quality along the shaft. The pile load tests establish the capacity and integrity of the piles to withstand the applied loading.
Deep foundation testing shall not be merely limited to the testing of pile after the installation. It shall cover the QA / QC aspects of testing during the construction of the pile, such as maintaining right properties of the drilling fluid, allowing proper hydration time, checking of pile positions, proper base cleaning, sounding checks, etc.
Keller has been credited for laying the foundations of a many of the world’s largest and iconic structures. Please tell us about a challenging project of geotechnical engineering and deep foundation, which not only saved time and cost but also ensured safety of the engineers throughout the project?
Building the foundations for a sustainable future is at the heart of everything we do. One of the projects which we executed was in India’s highest seismic zone with very loose deep soil stratigraphy. With our knowledge of local markets and ground conditions, and with our global knowledge base, we were ideally able to suggest and construct a sustainable foundation to support the LNG storage tanks (capacity of 160,000 cum), and the regasification terminal facilities. The proposed facility was to be constructed on the West Coast and located in the highest seismic zone (V) as per IS 1893. The subsoil was freshly reclaimed by hydraulic fill and was prone to liquefaction in the event of an earthquake.
Foundation design was quite challenging as the pile foundations were going to experience negative drag and very low lateral capacity, as envisaged. Keller designed and executed the foundation here with a unique combination of vibro compaction and vibro stone columns (deep Vibro Techniques). This solution eliminated the need of pile foundation in the entire plant and resulted in structures resting on an open foundation over the improved ground.
The technically robust solution addressed the very challenging geotechnical concerns and resulted in savings of carbon emissions as no steel and concrete was used for ground improvement, and use of in-situ densification process for vibro compaction and locally available stone for the vibro stone column work. Commercially, the solution gave attractive savings compared to the original foundation cost. Finally, the overall construction schedule was also reduced by three months, which benefitted the owners. The adoption of alterative foundation method resulted in 96% lesser CO emissions as compared to conventional piles (ref – IGC 2021, paper title - Moving towards Sustainable Ground Engineering).
In this project, we came across various safety challenges related to working close to the shoreline and handling multiple heavy machineries simultaneously. We took care of our employees by using structured risk management and safe work procedures, and incident management system. A strong leadership towards safety with timely delivery of superstructure construction works has been recognized by our clients and we have been awarded for being the best safety contractor.
How do you view the skill development programs in India specific to geotechnical engineering and foundation /underground structure construction?
In India, lots of good educational institutions like IIT/NIT/Universities offer geotechnical engineering /foundation courses in addition to full time/parttime online courses. Portals like NPTEL and CDEEP are also available.
However, in our opinion, there is still some disconnect between academics, field exposure, and implementation. This gap can be minimized through interaction between industry experts, academic, and the practitioners. In recent times, this gap has been identified by several companies, and they have started to collaborate with Institutions like IIT’s, the Deep Foundation Institute, Indian Geotechnical Society etc. They are working in a collaborative way to enhance the skills of operators, students, engineers, geotechnical practitioners, soil laboratories, and testing agencies. Few examples include DFI’s Educational Trust initiated student mentorship/industrial exposure program for development of young geotechnical engineers. Keller India has initiated full time paid YEDP/ EDP (Young Engineer Development Program) for create future talents and internships for skill enhancement.
What kind of positive impact will programs and events like DFI-I have in enhancing the performance of the geotechnical and foundation industry?
DFI in India supports introduction of new product to the Indian construction industry like CFA piles by doing field trials and explains the benefits to all the stakeholders. DFI forms industry and academic collaborations by conducting various events and bring new talent. DFI shares the knowledge of innovative projects to the industry through its newsletter and magazine. As a global platform, it connects contractors, consultants, and equipment manufactures in a single forum for better geotechnical solutions / advancements. It also encourages women in the construction field through the WiDFI committee.
Lastly, I would like to quote “Momentum is everywhere and we witnessed the same in the construction industry for building the nation. All it took was something to start the momentum going. many companies can master building good foundations and techniques, but it takes time, dedication, and discipline. At Keller, safety and quality are our top priority”.