DFI-India 2024: 13th Annual Conference
Program Highlights

1. Sustainability in Geotechnical Construction – A Global and Indian View

This talk will introduce the principles of sustainable development as defined by the UN SDGs. There are 17 Sustainable Development Goals, which every UN country has signed up to achieve by 2030. These Goals are global and holistic, covering all areas of sustainability. They are also used by several geotechnical and other construction companies to report on sustainability. This means the Goals become a common language to communicate on sustainability.

Why:

• Climate change is real. The world is a much hotter place. Extreme weather patterns are seen routinely. The Paris accord, signed by 196 countries agreed to limit temperature rise to below 2° C (preferably 1.5° C) compared to preindustrial levels to be achieved by the end of 21^st century.
• Drivers: There are several drivers for action to be taken on this, which range from new legislation, client, and employee demand, managing climate change risk and efficiency savings to name a few.
• Why is it relevant to the construction industry: Because it is one of the major contributors. 40% of the global emissions are from building construction & operation and foundations account for 15-23% of buildings embodied carbon. A major focus area is carbon reduction to achieve net-zero by 2050 in several countries and by 2070 in India.

How:

A major challenge is how to systematically reduce the carbon footprint in a steady manner so that the above net zero goals can be achieved. The talk addresses the 3 scopes of carbon reduction and how construction companies can work to reduce them.

Scope 1: Emissions from fuel use on site. These can account for up to 20% of total emissions. Methods to reduce this are presented using for example efficiency improvements, biofuels, electrification etc. Examples from real projects in Singapore, US and Norway will be presented.

Scope 2: Emission from electricity use in offices and yards: Options for efficiency improvements, use of eco power from hydro, solar and wind are discussed.

Scope 3: Emissions related to transport, travel, waste and most importantly materials (cement, concrete, steel) which can account for up to 80% of total emissions. The talk will give examples on how optimisation in transport and travel and the use of low carbon materials etc. can help in carbon reduction.

The talk initially starts with a global view and then moves to how the geotechnical construction industry in India is responding (with examples) and explores opportunities for the future.

2. Evaluation of Ground – Pile Interactions from Pile Load Tests

Deep foundations, especially, piles constitute a very crucial component of infrastructure development. Design and installation of piles pose challenges because of several aspects, viz., site conditions, variability of geotechnical parameters, methods of design, construction, etc. The design in particular is based on limited data from either laboratory measured parameters or results from in situ tests, integration of these over the length of the pile, but with non-accountability of installation effects on the parameters, empiricism in design methods, etc. The presentation firstly explores the variability in pile capacity estimation at three sites, alluvial and marine by three methods. It becomes imperative to conduct an initial monotonic or cyclic pile load test to validate the prediction. Conventionally this test is used casually to justify the design. However, it is established in the paper, that the load – settlement curve is a gold mine if analyzed rationally. The global ground – pile interaction parameters can be revealed and compared with those used in the a-priori design. Data from axial compression, pullout and lateral load, and bi-directional load tests are analyzed to identify and document possibly for the first time the fallacies and anomalies in our understanding of ground behavior/response and design approaches.

3. A novel, simple but effective method for assessing pile base resistance in sandy soils

As well known, due to punching failure mechanisms the full mobilization of pile base resistance qbu in sandy soils is attained at very large relative displacement w/d (w = pile head settlement; d = pile diameter), which may exceed or equal to 100% of the pile diameter. Nevertheless, it is generally estimated by theoretical methods based on the limit equilibrium. Several bearing capacity factors are available from literature, being those given by Beretzantev et al. (1961, 1965) the most widespread used in current practice. Therefore, the bearing capacity factors estimated by this approach are associated to pile settlement always inadmissible and then meaningless from a practical viewpoint. Furthermore, since the experimental detection of the pile resistance is carried out from the results of load tests run usually until to a relative settlement w/d at most equal to 10%, there is a gap between the theoretical evaluations and the experimental data. To overcome this issue, a novel, simple but effective analytical method for the prediction of the response at pile base is proposed, thus allowing for an estimation of the pile base load corresponding to a given displacement. The reliability of the proposed method is checked against 50 well-documented in-situ pile load tests performed worldwide (diameters from 0.4 m to 2 m and lengths from 6 m to 91 m), all of them of cast in situ type (bored, CFA and FDP) and embedded in sandy soils.

4. Failure analysis, Design & Installation of Offshore Conductor Piles – Case Studies

Conductor Pile is the first string used to support well apparatuses and equipment’s as a drilling diverter. Typically, these piles run from the seabed and set at depths providing a conduit to allow circulation of drilling fluid and case off unconsolidated formation. The conductors should have adequate bearing capacity to carry safely the loads due to equipment mounted on it and also the operational loads. The soil below the conductor base should not undergo hydraulic fracturing due to the pressure of the drilling mud. The main objective is to design and install conductor to meet the engineering and operational objective. Geotechnical challenges involve thorough characterisation of the ground, establish setting depths (to meet the drilling safety requirements) and to safely drive the piles to the design depths. The industry practice of estimating hydraulic fracture pressure and the setting depths often leads to either unconservative or overestimated design depths. Failure is imminent with unconservative estimates and/or lateral heterogeneity of stratigraphy. The contrary assessment leads to design and installation challenges. Very deep slender conductor piles pose driving challenges and at times surprise with hammers being damaged.

The keynote presents two case studies in Offshore South East Asia. The first on the failure of a live conductor piles (splitter wells) addresses the root cause analysis of failure and mitigative measures adopted in safely securing some slots of conductors, while the second case study discusses on evaluating the hydraulic fracture in determining the setting depths, pre-installation driveability analysis for hammer selection and compared with the observed installation parameters after successfully installing the conductors.

5. Advancement in Ground Improvement Techniques for The Construction of Load Supporting Columns in Soft Soils

The ground improvement techniques per se have not changed over many decades. The techniques used in the industry fall under one of the three categories: (i) consolidation, (ii) forming of load supporting columns (or combinations of (i) and (ii)), (iii) compaction. Equipment developments however did progress considerably in the last 2 decades. These developments allowed improvement of the products in areas of quality, cost, time and, offer solutions for difficult conditions which previously were not, or only with costly efforts be able to be resolved, due to limitations in the capability of the equipment. This Paper will report about the equipment and technique improvements under category (ii) above. The load supporting columns referred to are Stone Columns, Wet Deep Soil Cement Mix Columns and Full Displacement Columns (also known as rigid inclusions). For each of the products a very brief historical recap is advanced, and the basic technical principles for the type of column is explained for better understanding of the advancements made. At the end of each chapter there will be reference to a project on which the technique was used. Stone Columns Construction (SC) refers to the Hong Kong Boundary Facility project (marine) which involved the use of Gravel Pumps and the Pressure Chamber Injection System for the installation of the SC. The Deep Wet Soil Cement Mixing (DCM) refers to the 3rd Runway Project in Hong Kong which required the installation of large diameter DCM elements with cross sectional areas of up to 6 m2 into depths of 40 m. Both Hong Kong Projects needed to be partially carried out in headroom restricted conditions as a requirement of the Airport Aviation Department. Rigid Inclusions are referred to the extension of the Soekarno Airport, Jakarta, Indonesia where the technique was applied successfully.

6. Ground settlements from construction of the tunnels for the Crenshaw/LAX Transit Corridor Project

Los Angeles Metro awarded the $1.3 billion contract to Walsh/ Shea Corridor Constructors (WSCC) to build the Crenshaw/LAX Transit Corridor Project, an 8.5-mile light rail that will run between the Expo Line on Exposition Boulevard and the Metro Green Line at LAX Airport. The contract included eight new stations, five at grade level and three cut-and-cover braced excavations. The project passes through densely constructed areas beneath streets so extensive monitoring of surface movements was required. WSCC subcontracted Geocomp to provide real-time data from instrumentation to evaluate the construction effects on existing facilities of the underground tunnels and excavations and surrounding structures throughout construction. Geocomp provided instrumentation and monitoring for over one mile of twin bored tunnels, three cut-and-cover/station excavations, and one low excavation location. Geocomp collected and integrated data from more than 2,000 sensors in near real-time. The monitoring effort was quite successful in identifying excessive settlements of the street at the start of the project. Once the cause of these excessive movements was corrected, the tunnel construction continued with street level movements of less than one-half inch. This presentation will describe the monitoring approach and show the results. It will demonstrate the value of real-time monitoring to help minimized the ground movements and associated damage from excavations made in urban areas for tunneling. The presentation will show the results and benefits of the monitoring program and also demonstrate the value of using real-time instrumentation data to reveal unexpected performance in time to develop effective risk mitigation solutions.

7. Experience with Construction of Deep Raker Piles for Volta Bridge Project in Ghana

The Tema-Mpakadan Railway Project is the largest, and, probably the most ambitious railway project in Ghana. Covering nearly 100kms, the project includes an unprecedented 159 structures. The 300m steel bridge across Lake Volta, which is the most critical part of the project. The Volta Bridge consists of five spans of 60m each with the bridge made of steel girders.

Key aspects of the presentation:

1. Reverse Circulation Drill (RCD), Vibro Hammer, 260 MT and 150 MT cranes and tugboats from different countries have been brought in to execute straight and raker piles.
2. 1.6m diameter and 76m long raked concrete bored piles with permanent liners were installed as a part of the foundation system.
3. Procedures, sequence and the planning that went into installation of raker piles.
4. Special considerations like challenges in providing rollers, maintaining tremie position, concreting of the these raker pile will be highlighted.
5. Also includes results of drivability analysis done to verify effectiveness of available vibro driver in lowering the casing up to desired depth and challenges in inclined liner position.
6. Test results of post construction of piles.
7. Overall learnings from this challenging international project.