Speech Title: Statistical Mechanics of Rock Masses -- A rock mechanics from engineering geology

Abstract: This is an IAEG Hans Cloos Lecture given by the reciepient of Hans Cloos Medal. The speech is to talk about the following issues:

1. Statistical Mechanics of Rock Masses (SMRM) is a rock mechanics from Engineering Geology, which reflects the mechanical effects of major geological factors of rock masses, with systematical theory for fundamental research and applicable techniques for engineering practice.

2. Four basic SMRM models have developed including geometric probability model for rock mass structure, stress-strain relationship model, strength & failure probability model and permeability model. These models have been extended used in calculation of point engineering parameters for rock mass structure like joint volume density and directional RQD, stress and deformation like elastic modulus and Poisson’s ratio of rock mass, compressive and shear strength and failure probability, directional permeability, and quality rating of rock mass, etc. Numerical analysis has been developed to obtain point cloud of these parameters mentioned above for engineering analysis. SMRM has also applied for analysis of rock burst, stability and active reinforcement of rock mass.

3. A set of application techniques and equipment have been developed including a backpacked laboratory for rock mechanical tests on site which could obtain the deformation and strength parameters of rock and frictional angle of joint; a software -- “SMRM Calculation” for parameter calculation and a numerical module -- “modelSMRM” for Flac3D-6.0 have been developed for engineering analysis.

Speech Title: Engineering Geology in Africa: Challenges and Prospects

Abstract: Africa is sometimes looked upon as the dark continent that were colonised mainly for her resources by the then European Superpowers. Early development of infrastructure around large mineral deposits and extraction of deposits from surface and subsurface mines needed civil and mining engineering input (soil and rock mechanics). Colonial powers claimed mineral and other resources needed in Europe and of which Africa has an abundance. These historic events led to a continent under siege and the road to freedom for most of the local tribes started in the early 1960’s with sometimes unfortunate violent uprisings to overthrow the colonial powers. The early history of the infrastructure development on the continent and still ongoing extraction of raw materials and other resources needs sound infrastructure e.g, roads, railways and harbours. Civil engineers and geologists played a crucial role in this development from early on and still today.

The Geological Survey of South Africa established an Engineering Geology section in 1950 and local training of engineering geologists started in the early 1980’s at universities. In 1972 a local section of the AEG came into being and in 1974 the IAEG South African National Group was established.

The rest of Africa followed a rather unsatisfactory route where international funding organizations and mining companies use international guidelines and stipulate involvement of multinational firms to investigate, design and supervise developments, new mines, and larger construction projects. This led to limited local guideline and professional development in most African countries. The perceived and sometimes real unstable political environments don’t encourage international support for establishment of local expertise and strong local professional institutions.

African faces unprecedented challenges especially with regards basic human rights such as housing, clean water, sanitation, health services and secure food sources. The average temperature increase due to Climate Change is expected to be higher for the continent that the averages predicted for other continents, although the emission contributions are of the lowest. The challenges for engineering geology include amongst others safe housing development, sustainable material utilisation for extended infrastructure construction and especially factoring in a critical climatic variability parameter to compensate for future unknown, unexpected and catastrophic weather events that may put lives and infrastructure at risk. It is important to establish and recognise formal Engineering Geological training, codes of practice and guidelines for African conditions and professional institutions to build a strong, independent African Engineering Geological community.

Speech Title: Revisiting Engineering Geology Core Values. Experiences from the Integration of Geology to Engineering the Last Two Decades

Abstract: Today's knowledge and the powerful tools we have in our arsenal have increased our capacity to design and construct more efficiently and in more and more, difficult sites and reduce the uncertainty and the acceptable remaining risk. But we are not at the end of this route. It is still always not possible to have an unquestionable answer to many of the problems associated with the work and reach the degree of accuracy that characterizes the other sectors of Engineering. And this is due to many parameters: i) the spatial distribution of the geomaterials with uncertain or fuzzy margins, a dependency of the geologic evolution; ii) the big number of parameters with a broad dispersion of values often for the same geomaterial and difficult to test, iii) the laws of behaviour are still approximate. It is then obvious why the geological judgment for understanding the behaviour of geomaterials must be always present and why is so important. Hence, geological representativeness is key to achieving effective engineering design to meet higher demand for reliable input data related to ground properties required as input into numerical analysis. This is described in the definition of Engineering Geology.

Indeed, we have progressed significantly, in many fields, the last two decades in Engineering Geology. In 'putting numbers in geology' and ground investigation methods. The technological innovations have been also a powerful tool for analysing and managing geohazards. A trend of deviation of Engineering Geology can be seen internationally though. What happens so often to the Geology in Engineering Geology? Cases are observed with departure from the common ground in Engineering Geology, Soil Mechanics and Rock Mechanics, sometime with Engineering Geology not even standing up to its intellectual merits, methods and procedures. A geostatistical analysis of laboratory and field tests, a geotechnical classification value, a tectonic diagram generated automatically, thematic maps derived from a UAV or LiDar or Satellite images cannot dominate upon any other judgment and cover all our works and tasks. It always takes geological insight for one Engineering Geologist. We need to revisit our Engineering Geology 'core values'. To ensure that there is a good understanding and knowledge of geological processes by developing sound engineering geological models, preferably 3-D ones that are of primary importance in the planning of engineering projects. As Engineering Geologists, this is exactly our great advantage. Being able to answer: 'how is the ground?' and 'how the ground works?'.

To highlight the integration of Geology to Engineering in the design and construction of several projects in the last two decades, several examples will be presented.

Speech Title: Double-block Mechanics and Accurate Landslide Prediction

Abstract: Landslide is one of the major geological disaster causing huge casualties and economic losses each year across the world. The short-term prediction of landslides is well-known almost mission impossible for past human history. The creation of a new landslide monitoring system in 2009 totally turned over the situation. The landslides can be shown in a model of double blocks separated by a sliding plane. It can be successfully predicted by the new monitoring system which measures the Newton Force Variation along the slip surface of landslide. During the past 14 years, more than 700 monitoring sites, which covered different types of landslides, have been set up in China. Among those monitoring sites, 18 landslides have happened and all of them have been predicted by the system. The monitoring system can give a 3.5 to 20 hours of short-term warning time before the landslides. After analyzing the graphic results from all monitoring sides of different landslide types and weather conditions, the sharp decrease pattern on the graphics of Newton Force Variation was proven to be the only necessary and sufficient factor that indicating the happening of the landslide.

Speech Title: Global Tunnelling Updates, Innovations and Way Forward

Abstract: Despite the impact of the COVID-19 pandemic over the past three years, the global tunnelling industry continues to progress. Worldwide, the number of tunnelling projects is on the rise, particularly in the areas of railway tunnels, highway tunnels, urban subways, and underground space projects related to sustainable development initiatives. This presentation will present the latest developments, innovations, and future trends in the global tunnelling industry, covering three key aspects:

1. Overview of Major Global Tunneling Projects: This section encompasses ongoing significant tunnelling projects, including the construction of three major binational tunnel projects in Europe, urban subway projects, and the development of underground urban spaces worldwide.

2. Innovations in Tunneling Technology: It delves into recent technological innovations in the field of tunnelling, spanning advancements in preventive deformation controlled principles, support techniques, informative construction, the application of new materials, and environmental protection measures.

3. Future Trends in Tunneling Technology: It explores the future directions of tunnelling technology, encompassing mechanization, digitization, and the implementation of green, low-carbon, and sustainable development principles.

This presentation aims to provide comprehensive insights into the tunnelling industry, helping to gain a thorough understanding of current industry dynamics and future development directions.

Speech Title: Impact Mechanisms and Rational Design of Debris Flow against Multiple Rigid Barriers

Abstract: Debris flows are catastrophic geological hazards occurring around the world in mountainous regions, leaving trails of destruction along their paths. A common method to mitigate damages from large volumes of debris flows is to construct a large single reinforced concrete barrier at the end of the assumed flow channel. In contrast, erecting multiple rigid barriers with smaller sizes along the flow channel has emerged as an effective and environmentally friendly solution to progressively retain and decelerate large volumes of debris flow. This is because the construction of smaller multiple rigid barriers in steep terrains is not only more cost-effective and technically simpler but also reduces carbon footprint when compared to the construction of a large single reinforced concrete barrier. Despite these advantages, existing design criterion for multiple barriers is based on volume retention using barrier spacing only but neglects the effects of Froude number (Fr) during flow-barrier interactions. Since debris flows can occur with a wide range of Fr exhibiting different impact, overflow and landing mechanisms, neglecting these flow-barrier interactions can lead to uncertainty of barrier design. A rational design approach for multiple barriers should consider impact dynamics, overflow and landing mechanisms, as well as changes in flow kinematics prior to the impact on downstream barriers. Elucidating these complex mechanisms requires systematic investigation of flow-barrier interaction using well-controlled physical tests and numerical simulations. In this keynote, the impact mechanisms of debris flow against multiple rigid barriers are revealed and discussed from physical flume tests and numerical simulations. The physical flume tests are conducted in a 28-m-long flume to investigate the impact of 9 m3 debris flow against dual rigid barriers. Based on the calibration of the 28-m-long flume test, the numerical simulations are carried out for multiple rigid barriers using a fully coupled two-layer, two-phase material point method (MPM) with a flow volume up to 500 m3, which is a typical design volume adopted in Hong Kong. The effects of flow Fr and barrier spacing on the impact mechanisms of debris flow against multiple rigid barriers will be discussed. Finally, design recommendations for multiple rigid barriers will be illustrated.

Speech Title: Geo-engineering Aspects of the 6 February 2023 Devastating Kahramanmaraş Earthquakes of Turkey and Lessons Learned

Abstract: This paper includes the assessment of geo-engineering aspects of the doublet Pazarcık and Ekinözü earthquakes with moment magnitudes of 7.7 and 7.6, respectively. Both earthquakes occurred on 6 February 2023 at 4:17 and 13:24, respectively, in the southeast part of Turkey, affected 10 provinces and resulted in more than 50,000 causalities and heavy damages. In the reconnaissance study; measurements were taken and observations were carried out along the vicinity of the causative fault segments and on some buildings, some engineering structures and natural slopes, and grain size analyses of liquefied soils and accelaration records were assessed. The focal mechanisms of the both earthquakes indicated the characteristics of left lateral strike-slip fault with slight vertical component. A surface rupture with a total length of approximately 400km developed during these earthquakes as a result of the movement of some NE-SW and E-W trending segments of the East Anatolian Fault Zone. Strong motion records from the stations along the fault rupture and on the Arabian plate recorded much higher ground motions and duration of shaking was more than 70 seconds. Although the maximum ground accelerations in heavily affected cities were within the maximum ground acceleration assumed in the seismic design code of Turkey, the computed response spectra of some selected stations along the fault rupture zone were greatly exceeded the seismic design spectra of Turkey, and therefore, this issue should be reconsidered. Since large areas are covered by alluvial soils and groundwater table is shallow-seated in the earthquake region, wide-spread liquefaction occurred and lateral spreading on the shores of sea and lakes and banks of rivers were observed. But liquefaction was generally observed at non-residential areas and caused limited damages such as settlement, tilting and lateral displacements on some buildings, roads and a bridge along the shoreline in two towns and one village. Probably the liquefiable layer was quite thin and/or the cap soil was thick. Observations and measurements indicated that buildings having stories 2 or less were intact or slightly damaged and a maximum settlement of 200 cm due to liquefaction was observed at Gölbaşı. Furthermore, structural damage due to liquefaction-induced were quite limited despite similar buildings on firm ground were suffered heavy damage or collapses. In addition, the foundations of buildings experienced severe tilting were quite shallow and they were more than 5 stories. These earthquakes also resulted in wide-spread rock falls and giant landslides, one of them formed a landslide lake, along or in the close vicinity of the surface ruptures. Rock falls caused loss of life and some structural damage to built environments such as buildings, roadways, and railways. Example cases from the region demonstrated that particularly buildings with 1-2 storey are constructed according to the earthquake codes, the effect of surface ruptures on buildings are quite limited even the relative slip was more than 3 m, but linear structures, such as tunnels, roadways, railways anf etc. are damaged by surface ruptures. The causes of damage were almost the same as those seen in the previous earthquakes of Turkey.

Speech Title: Sustainable Infrastructure Development – Fundamentals and Global Challenges

Abstract: According to the 2021 Global Status Report for Buildings and Construction, buildings and construction together account for 36% of the total global energy use and 37% of energy-related carbon dioxide (CO2) emissions. The construction industry thus has a huge responsibility to implement specific action plans to achieve sustainable construction targets. Bringing sustainability to the construction industry is a challenging task that relies significantly on innovative materials and design/construction technologies. Through innovation, the construction industry can transition from being part of the problem to become part of the solution. As the global population is expected to reach 8.5 billion people by the year 2030, preserving non-renewable resources is a top priority to ensure the planet's survival. Sustainable solutions in construction industries are needed to deliver infrastructure that supports a desired quality of life for current and future generations while con-serving resources and energy.

In this presentation, importance of sustainable infrastructure development is discussed in conjunction with climate change. A particular emphasis is placed on sustainable benefits of geosynthetics, which have become essential and regular construction materials that are be used to facilitate construction, ensure better short-term and long-term performance and reduce the long-term maintenance cost in routine civil engineering works. The sustainable benefits of geosynthetics are then discussed along with relevant case studies on transportation infrastructure development that demonstrate the potential of geosynthetics to significantly reduce carbon footprints compared to traditional solutions. Recent advances in geosynthetics applications on transportation/geotechnical infrastructure systems are introduced with emphasis on fundamentals and global challenges. Finally, the pathway forward regarding geosynthetics technology within the framework of sustainable infrastructure development is discussed.

Speech Title: Radar Technologies for Landslide Monitoring and Rapid Mapping

Abstract: Radar technologies provide accurate and timely information on ground motion and therefore play a key role in landslide monitoring and rapid mapping. The radar systems used for these purposes can be ground-based or space borne. Ground-based radar systems are deployed in front of landslide-prone areas to monitor and detect ground displacements with very high accuracy. In particular, Ground-Based Interferometric Synthetic Aperture Radars (GB-InSAR) provide high-resolution images of ground displacements over time and are particularly useful for monitoring slow-moving landslides, such as earth slides or earth flows. Doppler radars are ground-based devices used for continous monitoring of fast-moving landslides such as rockfalls or debris avalanches. They use the Doppler effect for the early detection of areas of incipient instability. Space borne radar systems are mounted on satellites orbiting the Earth and provide a broader perspective by covering larger areas. They deliver accurate measurements of ground motion using interferometry techniques and are particularly useful for monitoring on a regional scale. The advancement of Persistent Scatterers Interferometric Synthetic Aperture Radar (PS-InSAR) techniques and the free availability of satellite radar imagery by the European Space Agency (ESA) have led to the introduction of the European Ground Motion Service as part of the European Earth Observation program Copernicus. National coverages are also regularly produced in various countries. Radar systems can be operated remotely without entering an unstable area, and they operate independently of weather conditions, providing monitoring data even in rain, fog, and cloud cover. For these reasons, they are particularly useful for early warning systems and post-event consequence assessment. In addition, radar systems provide real-time or near-real-time data, enabling rapid emergency response.

In summary, radar technologies, whether ground- or space-based, are valuable tools for landslide monitoring and rapid mapping, and provide important information for disaster management and mitigation. Effective early warning systems at regional, national, or local levels can be based on the integration of remote sensing data from the various radar systems, in situ sensor networks, and weather forecasting routines.