Civil Engineering encompasses wide field of study, some of which are structural engineering, transportation engineering, hydropower engineering, water resources, construction management and others. Geotechnical Engineering is also a branch of civil engineering, and it deals with the mechanics of soil and rocks, determining their suitability for the proposed construction of different structures. It is considered one of the most challenging subjects, partly because of the spatial variability of the soil and rock formations.
For instance, unlike structural engineering, there is no definite answer in geotechnical engineering. The strength property of concrete or steel can be defined with a fixed number, and units and can be modelled with appreciable accuracy in a computer. However, the strength property of soil varies to a larger degree. The strength parameters, cohesion, and friction angle, obtained from an investigation site might differ in horizontal and vertical directions. Choosing an appropriate material property would be facilitated if the number of samples/tests were increased.
One of the major challenges for geotechnical engineers in Nepal is to make decisions with the limited samples undertaken during the site investigation. As mentioned, spatial variations in heterogeneous materials can be significant and are equally difficult to quantify due to sparse sampling and testing results. In Nepal, for most types of projects, the extent of the investigation is largely dependent on its value in the eyes of the client or the project management team. There has not been an accepted standard or norms upon which all involved stakeholders can agree.
Talking about standards, we have been mainly following IS Codes since we don’t have our own geotechnical standards. The codes and standards followed are quite old. The codes aren’t supposed to be static documents and it must be updated regularly in relation with such unprecedented advances going in the field. Consolidating and implementing findings of research in practice should be given importance as much as the research itself. Only then the practitioners will be benefitted and the academicians’ work worthy. Else, spending a ton of money in the pursuit of increasingly specialized and obscure fields of research will make less sense. It is understandable that it shall be difficult to change the analysis/design procedures instantly based on new advances, but integrating them with codes and standards forms a reliable way with which every practitioner shall be more confident in using it.
During my one year of working as a geotechnical engineer and preparing soil investigation reports, I have referred to numerous reports prepared by different companies/practitioners. One major issue that stroke me was the non-uniformity in the methods adopted. For instance, varying equations for calculating the bearing capacity of the shallow foundation were used by different practitioners. As expected, IS Code was profoundly used for calculating bearing capacity based on the shear strength criterion. Others used empirical correlations like those given by Teng which are based on SPT values. For settlement in cohesionless soils, empirical relations like the Meyerhof and Bowles equation were used. Similarly, the use of the strain-influence factor method given by Schmertmann (1978) was also used. There are many other methods available in literature as well. All these methods produce different bearing capacity for the same investigated site. The empirical equations are derived by researchers with the data they possessed and may or may not be suitable for all cases/places. Such correlations must be calibrated by an in-situ test like a plate load test. In fact, an applied research project to calculate the bearing capacity of shallow foundations using an empirical equation based on SPT (for Kathmandu Valley – or defined regions) may be developed and be integrated into the geotechnical standard of Nepal, if developed in the future.
Engineers who are practicing the art should also be willing to update themselves with the new advances made in the field. One of the ways to encourage this is through the continuing professional development (CPD). In most countries, CPD is regulated by some authority like the engineering council, and to continue holding the license as an engineer they must demonstrate that they have taken part in learning some courses, attending conferences, etc. Such a system shall ensure new learnings that an average professional may not have otherwise experienced. (During my tenure as Graduate Engineer in Rural Access Programme 3 (RAP3), I was trained under CPD. I had to record all my activities and demonstrate my achievements to remain in the position of Graduate Engineer.)
Sometimes it is difficult for an average practitioner to understand the concepts made in recent developments/advances. Recent advances often include complex modelling and sophisticated laboratory procedures to define more soil parameters, which are beyond the understanding of an average practitioner. As such the role of professional societies (for example, Nepal Geotechnical Society(NGS)) comes into play. Inviting international guest lecturers along with local leading practitioners/academicians of the field is one of the ways to move forward. (To my knowledge, NGS have been conducting such activities, and it’s also organizing an International conference on 16-17 October 2022. (For further information: https://geomandu.ngeotechs.org/ ))
For a meaningful quantitative analysis of geotechnical problems, appropriate, sufficient, and reliable geotechnical data must be available. The problem of inadequate sampling may stay for a long time as it involves change in the mindset of many stakeholders. The quality of tests from laboratories on the other hand may be improved and it is within our control. Provided the same sample, if a direct shear test is issued to different laboratories, chances are that the test results are different by a wide margin. Many practicing lab technicians fail to appreciate the conditions under which the sample is being tested. For example, during sample preparation, it may require that the soil be compacted at natural moisture content and field density. However, many of them just accumulate the soil in the test box irrespective of weight, and moisture content and proceed to test.
The way forward for the geotechnical engineering scenario in Nepal is to develop its own code/standards that encompass its own geology and necessary procedures likewise. The code once developed should be updated based on the advances made in the field and as per the requirement. Slowly, the working stress method (global factor of safety) should be updated by the limit state method (load and factored resistance design) and then by reliability-based design methods (probabilistic approach).
Academics and researchers are doing a great job in producing new knowledge, but designers and contractors are marching on the same old path for a long time. There is a huge gap in the development of knowledge and its implementation. Research should be done collaboratively with industry and university. An excellent example for this is the ongoing research of Helical piles in Thailand. Such piles have been widely used in USA and Canada but it’s use, particularly in Asian countries have been quite limited. Helical Pile Thailand Co. Ltd. for the past few years have been doing research as well as providing services to its clients. Such applied research addressing the confusion/problems occurring in geotechnical practices should be given more priority. It would also be more appreciable if the researchers/practitioners document their case studies as it will be easier for practitioners to decide what’s working and what’s not.
These are some of the challenges and ways forward in my view.