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This paper is motivated by the Time Capsule Project (TCP) of the International Society for Soil Mechanics and Geotechnical Engineering (ISSMGE). The historical developments of geotechnical risk and reliability are reviewed for the past six decades. The key features distinguishing geotechnical and structural engineering are the natural origin of the ground and the lack of sufficient data to characterize the ground using the more familiar frequentist interpretation of probability. For the first feature, random field theory is applied to model spatial variability and the random finite element method or other methods are proposed for solving soil-structure interaction problems in spatially variable soil. For the second feature, compilation of databases is essential to serve as priors for Bayesian updating and more recently for Bayesian machine learning. There is a gradual evolution towards reliability-based design because probabilistic methods offer a pathway to address big data and implement data-centric geotechnics as one step towards digital transformation. Given the complexity of the natural ground (known unknowns can be large and there are unknown unknowns), engineering judgment remains important to bridge the gap between theory and practice. However, the role of engineering judgment needs to be updated as modern machine learning methods become more powerful. [ABSTRACT FROM AUTHOR]

In the process of pile foundation design and construction, pile foundation will produce different degrees of damage in order to protect the pile foundation from damage during the construction process. In this paper, three failure methods of pile foundation are analyzed by static simulation, namely the total deformation of the pile foundation, the maximum principal stress and the bending deformation of the pile body caused by excessive equivalent force. For the pile foundation, when the pressure value is between 2Mpa-3Mpa, the main stress, total deformation, and equivalent force of the pile foundation grow slowly, but when the pressure value exceeds 3Mpa, the deformation effect of the pile foundation increases significantly, and the distribution of the pile foundation is reasonably arranged in the later construction process to ensure that the pressure value of the upper part of the pile foundation is maintained at 2Mpa-3Mpa, so as to greatly reduce the damage of the pile foundation, of course, you can also use concrete materials with higher strength grades to reduce the deformation effect of the pile foundation and protect the pile foundation from being damaged. [ABSTRACT FROM AUTHOR]

Monitoring geotechnical structures and providing real-time early warning is a key measure to mitigate the impacts of disasters (slope slip, subsidence, dam deformation, bridge settlement, etc.). The fiber Bragg grating (FBG) flexible sensor, developed by the combination of flexible material and an FBG sensor, is widely used in geotechnical engineering health monitoring due to its excellent performance. The flexible sensor can perform regional and quasi-distributed measurements of the displacement field of the measured structure, and accurately reflect the operating state of the engineering structure. However, in practical engineering applications, factors such as the strain-transfer rate between the flexible substrate and sensing points, the displacement reconstruction algorithm, and the arrangement interval of the sensing points can cause measurement error, which, in turn, leads to a decrease in the displacement-measurement accuracy. In this paper, the following analysis is performed by means of theoretical derivation and model establishment. The influence of the length, width, and thickness of the cemented layer, the shear modulus of the flexible substrate, and the radius of the groove on the strain-transfer rate were analyzed, and the referential parameters were determined. The displacement reconstruction algorithm is essentially a recursive algorithm, which inevitably introduces cumulative error; the relationship between the layout interval of the sensing points and the measurement error is discussed. Considering the fabrication cost of the sensor and the allowable range of error, a sensing-point-layout interval of 100 mm was chosen. The feasibility and effectiveness of the simulation theory were verified by carrying out deformation-sensing experiments on the developed FBG flexible sensor. The research results can theoretically guide the packaging and fabrication of the FBG flexible sensor, thereby improving the measurement accuracy of the flexible sensor for the measured structure. [ABSTRACT FROM AUTHOR]

Based on the salp swarm algorithm (SSA), this paper proposes an efficient metaheuristic algorithm for solving global optimization problems and optimizing two commonly encountered geotechnical engineering structures: reinforced concrete cantilever retaining walls and shallow spread foundations. Two new equations for the leader- and followers-position-updating procedures were introduced in the proposed adaptive salp swarm optimization (ASSA). This change improved the algorithm's exploration capabilities while preventing it from converging prematurely. Benchmark test functions were used to confirm the proposed algorithm's performance, and the results were compared to the SSA and other effective optimization algorithms. A Wilcoxon's rank sum test was performed to evaluate the pairwise statistical performances of the algorithms, and it indicated the significant superiority of the ASSA. The new algorithm can also be used to optimize low-cost retaining walls and foundations. In the analysis and design procedures, both geotechnical and structural limit states were used. Two case studies of retaining walls and spread foundations were solved using the proposed methodology. According to the simulation results, ASSA outperforms alternative models and demonstrates the ability to produce better optimal solutions. [ABSTRACT FROM AUTHOR]

The geotechnical centrifuge applied in various geotechnical engineering fields provides physical data for investigating mechanisms of deformation and failure and for validating analytical and numerical methods by simulating and studying the geotechnical problems. The basket, as one of the important components used to place the inspection model of centrifugal test, is designed to withstand complex loads. This paper presents an optimization design method for the basket based on the weighted B-Spline Finite Cell Method (FCM) and the globally-convergent method of moving asymptotes (GCMMA). In order to obtain a superior design solution, four topological configurations, i.e., original single web, porous dual web, open deep groove dual web, and connected closed dual web, are investigated and optimized. The mass is selected as the optimization objective, while key shape parameters and stress are regarded as design variables and the constraint, respectively. By optimization, the final masses of the four configurations are reduced greatly compared with the initial configurations, where the greatest weight loss, in case 4, is 10.6%. This indicates that the weighted B-Spline FCM and GCMMA can be well applied for shape optimization of structure in engineering design. In contrast to the final single web adopted in the traditional basket design in case 1, the final configuration in case 4, i.e., connected closed dual web, has the least mass. The final mass is reduced by 133.38 kg when the centrifuge strength requirement is met. Therefore, the final configuration in case 4, where the maximum von-Mises stress is 398.72MPa and mass is 781.82kg, is superior to the three other configurations. [ABSTRACT FROM AUTHOR]

This paper examines the importance of geotechnical optimization techniques for soil engineering applications, with a particular emphasis on evaluating geotechnical structures. Due to its prevalence in civil engineering, the complex interplay of geotechnical, structural, and financial considerations necessitates a trial and error approach. The study focuses on design elements, geometric dimensions, and volume considerations in order to highlight the economic viability of reinforced concrete retaining walls. Three code files are created using MATLAB to analyze their impact on active and passive thrusts and, as a result, the structure's volume. The slope angle, backfill overload, and friction angle are varied. The results demonstrate the effectiveness of using evolutionary algorithms to precisely optimize a single goal and demonstrate that this approach can enhance the design of retaining walls in reinforced concrete. This method demonstrates the ability to improve design procedures in this crucial area, which makes it an invaluable resource for structural engineering researchers and civil engineers. [ABSTRACT FROM AUTHOR]

Recent accidents in underground structures have raised the risk awareness of the geotechnical engineering community. Geotechnical design is subject to significant uncertainties in load and strength parameters as well as in engineering models. However, engineering models which objectively address such uncertainties in design are still scarce. This paper presents an objective framework for the quantification of the risks involved in underground structures excavated in fractured rock masses, where structural failures may occur due to block falls. The framework considers the structure as a distributed system, where falling block probabilities are integrated over the main structural dimension. Random block size and geometry, arising from random joint orientation, are taken into account, as well as uncertainties in joint strength and geometrical parameters. A cost function is used to quantify failure consequences in terms of the block size. The framework is demonstrated in an application to a case study involving a real structure: the Paulo Afonso IV power station cavern. Results of the case study show that the studied cavern presents high reliability and very low risk. The framework proposed herein is shown to be a practical tool for the risk evaluation of underground structures constructed in rock masses, such as caverns and tunnels. [ABSTRACT FROM AUTHOR]

The seismic performance of geotechnical structures placed close to active faults is influenced by the peculiarities of the near-source seismic wave propagation. This issue is of paramount importance for large and massive structures, such as earth dams, for which the strong variability of the ground motion at the foundation level and the contribution of the vertical component of the motion could induce high differential settlements in the embankment with an increased risk for the structure. When modelling a structure in near-source conditions, the domain of analysis should be considerably wider than that typically adopted in the engineering field, since the seismic source and the propagation medium up to the reference site should be added to the structure and to the soil volume interacting with it. The paper illustrates the procedure developed to define the input motion at the Conza Dam site (Italy) during the 1980 Irpinia earthquake (November 23, 1980; Mw = 6.9). Due to the short distance of the site from the fault area, the Conza Dam is representative of several large dams placed in near-source areas in Italy and worldwide. The paper focuses on (1) the reconstruction of the regional structure of the Campania-Lucania region on the basis of former literature studies and on a new calibration of the 1D velocity model at regional scale; (2) the definition of the reference input motion at the site of Conza Dam with highlights on the spatial variability of the ground motion below the dam foundation and related effects on the structure. [ABSTRACT FROM AUTHOR]

Design of a pile foundation involves solving the complex problem of transferring loads from the structure through the piles to the underlying soil. It involves the analysis of a structure-pile system, the analysis of a soil-pile system and the interaction of the two systems, which is highly nonlinear. Close cooperation between the structural engineers and geotechnical engineers is essential to the development of an effective design. Many factors must be considered when selecting an appropriate foundation for a hydraulic structure. Information is presented to identify the feasible foundation alternatives for a more detailed study. This coordination extends through plans and specifications, preconstruction meetings and construction. Some of the critical aspects of the design process require coordination. In this paper, a comparative study is made on the sesmic behavior of Soil-Structure Interaction (SSI) of RC building with homogeneous and non-homogeneous soil conditions. [ABSTRACT FROM AUTHOR]

An earthquake of moment magnitude (Mw ) 7.8 struck the central Nepal at 11:56 am on April 25, 2015. More than 9,000 people were killed and thousands of residential buildings, and hundreds other structures were also destroyed. An aftershock of moment magnitude (Mw ) 7.3 hit northeast of Kathmandu on May 12 after 17 days of main shock which caused additional damages. Immediately after the earthquake, authors undertook a field investigation and visited the affected areas. Strong motion records from both earthquakes and their impacts on structures as well as geotechnical issues are presented in this paper. Most of the structures in Nepal are made of adobe, unreinforced masonry, and reinforced concrete. Failure mechanisms of those buildings are briefly explained in this paper. Geotechnical aspects such as soil liquefaction, slope failures, settlement and lateral spreading, and site amplification effects that considerably influenced the damage patterns at many areas are briefly discussed as well. The lessons learnt from this earthquake are also summarized in this paper. [ABSTRACT FROM AUTHOR]

The Seismic Microzonation of level 3 (SM3) is nowadays a world-wide accepted tool for the mitigation of seismic risk. The SM3 is a complex process involving different disciplines ranging from Geology and Applied Seismology to Structural and Geotechnical Engineering. The outcome of a SM3 is presented on a zoning map in terms of a selected ground shaking intensity parameter and susceptibility to main ground instability (soil liquefaction, settlements, landslides, fault ruptures). In an advanced SM3 study for a given area, four main interdisciplinary steps can be recognized: (1) definition of the reference input motions, (2) construction of the subsoil model, (3) performing of numerical analyses and computing of amplification factors, (4) identification of zones with different geotechnical hazard potential and drawing up of the SM3 map. After the 2016–2017 Central Italy seismic sequence, intensive studies have been performed to obtain SM3 maps in 137 municipalities most damaged by the earthquakes. The aim of these studies has been to obtain a clear background on site effects to perform a correct reconstruction of the municipalities. In the paper, main results and critical issues of the above-mentioned steps of SM3 procedure are discussed together with some remarks on the use of SM3 output in supporting seismic design for reconstruction. [ABSTRACT FROM AUTHOR]

Vertical anchor plates are often provided to increase the performance of various geotechnical engineering structures such as sheet pile walls, bulkheads, bridge abutments and offshore structures. Hence, the safe design of such structures needs a better understanding of the 3D behaviour of the anchor plate. This paper presents and discusses the results obtained from a series of 3D finite-difference analyses of vertical square anchor plate embedded in cohesionless soil. The 3D model is found to closely predict experimental pullout load–displacement relationship. The failure mechanism observed in the numerical model is found to be very similar to the failure reported in experimental studies. For a given embedment depth, the stiffness of the breakout factor–displacement response substantially reduces with increase in anchor plate size. However, the ultimate reduction in anchor capacity is found to approximately 8% with an increase in anchor size from 0.1 to 1 m. Numerical analysis reveals that at deeper embedment depth, the friction angle of sand is the critical parameter in enhancing the performance of anchor plate. The obtained 3D model results are then compared with the published results and are found to be reasonably in good agreement with each other. [ABSTRACT FROM AUTHOR]

Rock strength is imperative for the design and stability analysis of engineering structures. The Mohr–Coulomb (M-C) criterion holds significant prominence in geotechnical engineering. However, the M-C criterion fails to accurately capture the nonlinear strength response and neglects the critical state of rocks, potentially leading to inaccuracies in the design phase of deep engineering projects. This study introduces an innovative stress-dependent friction angle and cohesion (SFC) for the M-C criterion to capture the nonlinear strength responses of intact rocks, spanning from non-critical to critical states (brittle to ductile regions). A novel method for determining these stress-dependent parameters at each corresponding σ 3 is initially introduced. Subsequently, an examination of the confinement dependency of the friction angle and cohesion is conducted, leading to the derivation of the SFC model. The SFC-enhanced M-C criterion, utilizing parameters obtained from triaxial tests under lower σ 3 , demonstrates the capability to delineate the complete non-linear strength envelope from brittle to ductile regions. Validation through triaxial test data confirms that the predictions of the SFC-enhanced M-C criterion accurately correspond to the strength characteristics of the tested rocks. [ABSTRACT FROM AUTHOR]

Typical underground water storage facilities consist of reinforced concrete tanks and pipes. Although methods of their analysis are well developed, the use of these methods does not always give unambiguous results, as presented in the paper. An example of underground tank is considered in which cylindrical roof collapsed during construction under soil and excavator loads. The causes of failure are investigated with deterministic and stochastic models. In the first step nonlinear finite element analysis including soil-structure interaction was performed to examine overall level of the structural safety, which was found satisfactory thus not explaining the collapse. In the second step an analytical stochastic model was developed and analysed with emphasis to sensitivity. The last analysis explained the collapse as a complex of unfavourable states for considered variables and the failure was recognised as a mixed construction-geotechnical-structural problem. The key role played backfill properties and its depth. [ABSTRACT FROM AUTHOR]

Ralph B. Peck (1912–2008), graduate and doctor of philosophy in civil engineering (1934 and 1937 respectively) from the Rensselaer Polytechnic Institute, was one of the major contributors to the development of geotechnics in the twentieth century. Born in Winnipeg (Manitoba) as an American national, he was influenced from childhood by the world of civil engineering through his father, Orwin K. Peck, who was a civil engineer, mainly as a structural engineer in the railway sector. In the absence of job offers as a structural engineer, Ralph Peck arrived at Harvard University in 1938 to attend the soil mechanics courses taught by Arthur Casagrande, which guided Peck's professional career towards geotechnics. In addition to Casagrande, Peck had the opportunity to meet and work with other very important people related to geotechnics: Albert E. Cummings, Laurits Bjerrum, Alec W. Skempton and especially Karl Terzaghi, with whom he established a great friendship, in addition to providing support, professional advice and performing important work, such as the Chicago Subway Works. Peck actively dedicated himself to consulting work, which led him to visit 44 states within the United States and 28 countries on five continents. In addition, he also participated in research work where he was asked and was a committed lecturer at the University of Illinois, where he was a professor for 32 years. The objective of this paper is to analyse, through Peck's biography, his contribution to the field of geotechnics based on his research, teaching and consultancy work, and through the influence of Peck on other important people in the field, such as Karl Terzaghi. [ABSTRACT FROM AUTHOR]

The special collection on Advances in Hydraulic Structures Engineering is available in the ASCE Library (https://ascelibrary.org/jhend8/advances hydraulic structures engineering). Nowadays, computational fluid dynamics (CFD) modeling and artificial intelligence techniques are common complements to the more classical physical modeling and direct measurement instrumentation to aid in analyzing complex fluid flow features around hydraulic structures. Though the special collection covers a broad range of hydraulic structures-related topics, the papers presented represent only a sample of the many relevant topics and challenges facing the field of hydraulic engineering. [Extracted from the article]

Summary: Over the past few decades, soil densification has been widely employed to reduce the liquefaction hazard or consequences on structures. The decision to mitigate and the design of densification specifications are typically based on procedures that assume free‐field conditions or experience. As a result, the influence of ground densification on the performance of structures and the key mechanisms of soil‐structure interaction remains poorly understood. This paper presents results of four centrifuge tests to evaluate the performance of 3‐ and 9‐story, potentially inelastic structures on liquefiable ground with and without densification. Densification was shown to generally reduce the net excess pore pressures and foundation permanent settlements (although not necessarily to acceptable levels), while amplifying the accelerations on the foundation. The influence of these demands on the performance of the foundation and superstructure depended on the structure's strength and dynamic properties, as well as ground motion characteristics. In addition, densification tended to amplify the moment demand at the beam and column connections, which increased permanent flexural deformations and P‐Δ effects (particularly on the heavier and weaker structure) that could have an adverse effect on foundation rotation. The experimental results presented aim to provide insight into the potential tradeoffs of ground densification, which may reduce foundation permanent settlement, but amplify shaking intensity that can result in larger foundation rotation, flexural drifts, and damage to the superstructure, if not considered in design. These considerations are important for developing performance‐based strategies to design mitigation techniques that improve performance of the soil‐foundation‐structure system in a holistic manner. [ABSTRACT FROM AUTHOR]

In this paper practical techniques are introduced for detailed modeling of soil-pile and soil-abutment interaction effects for integral bridges (IBs). Furthermore, a parametric study is conducted to determine appropriate structural configurations and geotechnical properties to enhance the seismic performance of IBs. For this purpose, numerous nonlinear structural models of a two-span IB including dynamic soil-bridge interaction effects are built. Nonlinear time history analyses (NTHA) of the IB models are then conducted using a set of ground motions with various intensities. In the analyses, the effect of various structural and geotechnical properties such as foundation soil stiffness, backfill compaction level, pile size and orientation, abutment height and thickness are considered. The results of NTHA are then used to assess the effects of these properties on the seismic performance of IBs in terms of member forces and deformations. It is found that while the proposed modeling techniques for IBs are easy to implement in commercially available structural analysis programs, they are also computationally efficient. However, the proposed structural model may not be used to study the soil deformations along the length of the embankment. For the IB and modeling approach under consideration, the bridge seismic response is found to be insensitive to the length of the embankment and damping of the embankment soil. Furthermore, IBs built with shorter and thinner abutments as well as large steel H-piles oriented to bend about their strong axis exhibit better seismic performance. [ABSTRACT FROM AUTHOR]

It is of great significance to study the interactions between structures and supporting soils for both structural engineering and geotechnical engineering. In this paper, based on the refined two-parameter elastic foundation model, the bending problem for a finite-length beam on Gibson elastic soil is solved. The effects of axial force and soil heterogeneity on the bending behaviours and stress states of beams on elastic foundations are discussed, and the parameters of the physical model are determined reasonably. The beam and elastic foundation are treated as a single system, and the complete potential energy is obtained. Based on the principle of minimum potential energy, the governing differential equations for the beam bearing axial force on the Gibson foundation are derived, and the equations for attenuation parameters are also defined. The problem of the unknown parameters in foundation models being difficult to determine is solved by an iterative method. The results demonstrate that this calculation method is feasible and accurate, and that the applied theory is universal for the analysis of interactions between beams and elastic foundations. Both axial force and soil heterogeneity have a certain effect on the deformation and internal force of beams on elastic foundations, and the vertical elastic coefficient of foundations is mainly determined by the stiffness of the surface soil. Additionally, attenuation parameters can be obtained relatively accurately by an iterative method, and then the vertical elastic coefficient and shear coefficient can be further obtained. This research lays a foundation for the popularisation and application of the two-parameter elastic foundation model. [ABSTRACT FROM AUTHOR]

Unmanned aerial vehicles (UAVs) mounted with remote sensors have been widely used in architectural, civil, and environmental engineering fields. In particular, UAVs are applied for monitoring civil infrastructure to analyze the cause of failure in forensic engineering. This paper reviews UAV sensors and their applications in the context of forensic engineering. First, RGB, non-RGB cameras (e.g., IR thermal, multispectral, and hyperspectral detectors), and non-imaging sensors (e.g., LiDAR and SAR) are categorized by their emission methods. The advantages and disadvantages of sensors with different wavelengths, such as penetration capability and resolution, are described. Thereafter, application cases are individually presented in the geotechnical, structural, and water infrastructure fields. Different failures in each field are described: geotechnical engineering (slope failure, ground deformation), structural engineering (the stability, durability of infrastructure), water infrastructure engineering (harmful algal blooms, oil spill). Finally, the challenges of current UAV technology and recommendations for further study in forensic engineering are addressed. [ABSTRACT FROM AUTHOR]

Seismic analysis and design of pile foundations in weak soil strata to support oil tanks are of great importance to geotechnical practitioners. This paper presents an actual field study and dynamic soil-structure interaction (DSSI) analysis for an oil tank foundation design in weak soil strata for the Kafza site in Iraq, which is located in a seismically active region. For the particular in situ soil profile, a pile group foundation is proposed comprising a 24·1 m dia. by 1·5 m thick pile cap connecting together 89 piles, each pile being 800 mm in diameter and 26 m long. The foundation system was modelled using the finite-difference-based geotechnical program Flac3D to carry out detailed DSSI analysis. Field pile load test data for a static analysis were used for validation of the Flac3D model. The outcome of a probabilistic seismic hazard assessment was used to estimate target input motions resulting in maximum bending moments of 114 kN.m and maximum settlement of 21·9 mm for piles under dynamic conditions. The results obtained, comprising total and differential settlements and bending moments, were used for the final design of the proposed pile foundation and can be used for similar practical applications. [ABSTRACT FROM AUTHOR]

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Actual fatigue life of an existing offshore platform typically deviates from that intended by its designer because aging platforms commonly experience some degradations, mechanical damages, repairs and modifications, and come across demands for the service extension. The current multidisciplinary paper focuses on different aspects of the remaining fatigue life assessment of an aging offshore platform. In the course of a case study, it describes a hindcasting technique for quantitative estimation of the long-term wave climatology, methods for geotechnical/structural modelling of the platform foundation to evaluate the piles fatigue damages accumulated during their driving and in-place service and the outlines for a spectral fatigue modelling and analysis of the fatigue damages to welded structural joints. Potential limitations in the available codes of practice, regarding the fatigue life assessment of existing offshore structures, are highlighted. The reliability of the fatigue life evaluations, possible remedy measures and some fatigue integrity monitoring techniques are discussed. [ABSTRACT FROM AUTHOR]

The application of the limit state design (LSD) in the geotechnical area has increased over the last two decades, but this approach is not yet widely used in dam safety evaluation. This study aims to widen the use of the LSD application for large dams, in particular concrete gravity dam foundations. This paper starts with a brief reference to the LSD approach in recently published guidelines for dam design, followed by a detailed description of the LSD formulation when applied to the foundation of concrete dams. The relevance of the joint application of the concepts of ultimate limit states and of numerical methods is highlighted. Comments are made regarding the criteria adopted in order to determine the characteristic values of the material mechanical properties, with an emphasis on discontinuities, taking into account the spatial variability. The sliding safety assessment of the foundation of a concrete gravity dam using the LSD and a discrete element model, both in persistent and in an accidental design situation, is presented. Results led to the conclusion that the LSD methodology may be followed for dam foundation design with the partial factor values prescribed in Eurocode 7. [ABSTRACT FROM PUBLISHER]

The paper presents aims to provide analysis of non-waste technology of producing piled foundations of hydraulic engineering structures. The authors introduce a complexity of additional technical and technological steps making possible to both diminish the work-load and cut the time required. The paper also describes main stages of the work and points out the main drawbacks of the traditional technology. The authors prove that on condition of proper technique training and experience it is possible to design and produce pile fields characterized by minimal materials consumption thus saving 10-15% of zero circle estimated cost and cutting the time required for construction. [ABSTRACT FROM AUTHOR]

Numerical modelling represents a powerful tool not only for special geotechnical calculations in cases of complicated and difficult structure design or their foundation conditions, but also for regular tasks of structure foundation. Finite element method is the most utilized method of numerical modelling. This method was used for calculations of the retaining wall monitored during 5 years after construction. Retaining wall of the parking lot with the facing from gabion blocks was chosen for numerical model. Besides the unfavourable geological conditions, a soft nature of the facing was also a difficult part of the modelling. This paper presents the results of the modelling when exact geometry, material characteristics and construction stages were simulated. The results capture the trend of displacements even though the basic material models were utilized. The modelling proved the ability of the finite element method to model the retaining structure with sufficient accuracy as well as reasonable demand on quality and quantity of input data. This method can then be used as a regular design tool during project preparation. [ABSTRACT FROM AUTHOR]

This paper describes the evolution of full face excavation from the mid 1980s to the present. During this time, more than 1,000 km of tunnels have been designed, excavated and completed using full face excavation, with cross sections ranging in size from 120 to 220 m2, in different geological and geotechnical conditions, near the ground surface or at depth. Starting from the basic concepts of the approach (ADECO-RS) applied at the tunnel design stage and during construction, the experience gained and the lessons learned are summarised. It is shown how full face excavation has been developed and improved through the experience gained from the construction of both road and railway tunnels in the past thirty years. In order to highlight the current stage of development, with new materials, technologies, modelling methods and increased capacity in observation and real-time monitoring of tunnel behaviour becoming available, the case of the Sochi Tunnel in Russia is presented and a comparison with the New Austrian Tunnelling Method (NATM) is illustrated. [ABSTRACT FROM AUTHOR]

Rock is a kind of heterogeneous natural engineering material. Rocks in geotechnical engineering are often in a cyclic loading state. Investigation into the localization evolution law of rock deformation under cyclic loading can provide theoretical support for the stability of geotechnical engineering structures. The study simplified the cyclic loading conditions as one constant amplitude cyclic loading condition and one graded constant amplitude cyclic condition. The tests of red sandstone specimens were carried out under the two cyclic loading conditions. The deformation images of specimens during the tests were collected by CCD camera, and based on the digital speckle correlation method, the displacements evolution laws of deformation localization bands of specimens during constant amplitude cyclic loading were analyzed. The analysis finds that during the whole process of cyclic loading, the displacements of localization bands fluctuate upward with the loading and unloading stress. There is a time lag for the displacements relative to the stress change, and with the increase of cyclic number, there is a cumulative effect for the displacements. In the cycle, the values of lag time at the vertexes of the displacements of localization bands fluctuate steadily at the early stage of cycle and fluctuate upward at the later stage of cycle relative to the vertexes of loading stress. The values of lag time at the bottom point of the displacements of localization bands fluctuate steadily with the increase of cyclic number relative to the bottom point of unloading stress. When loading or unloading to the same stress in the whole cycle, the displacements of localization bands increase with the increase of cyclic number respectively. The displacements of unloading process are greater than those of loading process under the same stress during each cycle. With the increase of cyclic number, the displacements of localization bands experience slow evolution stage and accelerated evolution stage obviously. Before the failure of specimens, the displacement values of localization bands at the bottom point of unloading will be evidently close to the displacement values at the vertex of loading, and this phenomenon can be used as a precursor information of the instability failure of rock specimens or rock structures under cyclic loading station. The research in this paper can provide a new characteristic mechanical monitoring quantity for the instability failure of geotechnical engineering materials or structures under cyclic loading. That is, in a particular stress environment, when the deformation value of low stress state and relative high stress state both increase with time and the increase rate of the deformation value corresponding to low stress is obviously greater than that corresponding to high stress, the failure of geotechnical materials or structures will occur. [ABSTRACT FROM AUTHOR]

Abstract Finite element (FE) analysis in geotechnical engineering often involves entities which can be represented as one-dimensional elements in three-dimensions (e.g. structural components, drains, heat exchanger pipes). Although structural components require an FE formulation accounting only for their mechanical behaviour, for the latter two examples, a coupled approach is necessary. This paper presents the first complete coupled thermo-hydro-mechanical FE formulation for one-dimensional beam elements for three-dimensional analysis. The possibility of deactivating each of the systems enables simulation of both coupled and uncoupled behaviour, and hence a range of engineering problems. The performance of these elements is demonstrated through various numerical simulations. [ABSTRACT FROM AUTHOR]

We present two time-domain algorithms derived from the popular Newmark’s time integration algorithm, to reconstruct the input force excitation from the vibration measurements. While the first method uses a direct formulation of the time integration algorithm, the second one uses a regularization tool to solve the associated inverse problem. A modified regularization technique is employed to improve the accuracy of the identification problem. Numerical studies with limited measurements, with measurement noise, multiple load identification etc., are presented to investigate the practical applicability of the two methods. Studies have clearly favored the inverse algorithm with modified regularization technique. Finally modeling errors associated with force reconstruction are investigated and a technique is proposed to identify the system parameters simultaneously while reconstructing the input dynamic force, using a recently developed quantum particle swarm optimization algorithm developed by the authors. The numerical simulation studies presented clearly indicate that the force, as well as the system parameters, can be identified accurately using the proposed algorithm. [ABSTRACT FROM AUTHOR]

A simplified approach for the nonlinear analysis of the load-displacement response of a single pile is presented using the load-transfer approach. In the present method, a hyperbolic model is adopted to simulate the load-displacement response of both the pile base and the shaft. Using the Mindlin displacement solution of the elastic half-space, the pile end settlement induced by the skin friction of pile is calculated. Based on the present analytical method, a highly effective iterative computer program is developed for the analysis of the response of a single pile. The validity of the present method is then demonstrated with the results of the load tests carried on instrumented piles. The calculated results indicate that at all loading levels, the proposed method is generally in good agreement with the well-documented field test results and the calculated results derived from other approaches. It is noted the pile head displacement obtained from the present approach increases with increasing failure ratio of skin friction and end resistance at the same loading level. It is also observed that the influence of the failure ratio of skin friction to the pile head displacement is slightly larger than the influence of the pile end resistance. [ABSTRACT FROM AUTHOR]

The current state of practice in soil-structure interaction (SSI) modelling in New Zealand was investigated through an industry-wide questionnaire. This used a mixed methods, sequential explanatory research design involving the collection of quantitative and qualitative questionnaire data, as well as follow-up focus groups. Several statistically significant relationships were observed for SSI modelling approaches between different engineering fields, company sizes, and years of experience. The key findings from this study suggest that there is no consensus on the best SSI analysis methods, modelling strategies, or guidelines to be used. Overall, fixed base analysis remains the most popular method across all company sizes and number of years of industry experience. Engineers from large companies reported higher consideration for SSI modelling and use of performance-based design for design projects, which perhaps reflects the scale and complexity of projects carried out in those companies. However when SSI is considered, analyses are typically limited to nonlinear vertical springs under the foundation as part of a dynamic analysis. Use of SSI for buildings is typically limited to seismic assessments and complex or otherwise high importance structures. However, bridge engineers routinely used pushover analyses with linear and nonlinear springs and dynamic analyses with nonlinear springs, in contrast with the rest of the industry. There is further room to improve on the quality of communication and interaction between structural and geotechnical engineers. A lack of specific guidance on when SSI should be considered was reported, alongside broader training issues to ensure that structural and geotechnical engineers fundamentally understand the requirements and input/output needs of each role. [ABSTRACT FROM AUTHOR]

The objective of this paper is to present abacuses obtained from a parametric study of deep-lined tunnels using a numerical finite element model. This numerical model was implemented in software GEOMEC91, which is a two-dimensional axisymmetric model that considers the progress of excavation and the placing of the lining through the activation and deactivation of elements. It is adopted a step of excavation constant (1/3 of radius), constant velocity and circular cross section along the tunnel axis. It is used for rock mass a viscoplastic constitutive law with von-Mises criterion of viscoplasticity without hardening whose deformation rate over time is given by the Bingham model. The lining uses a linear elastic constitutive law. In total are 1716 analysis presented in 60 abacuses that show the value of ultimate convergence (Ueq) due to tunneling speed. In addition, it is shown an example of the use of the abacuses to determine the ultimate convergence (U,,,) of the tunnel and pressure (Peq) on the lining. [ABSTRACT FROM AUTHOR]

A new simplified approach to the hyperstatic reaction method (HRM) for the analysis of segmental tunnel linings is introduced. The influence of segmental joints on the lining behaviour is taken into account by considering opening/rotation of the joints under external loads, which cause a reduction in the contact surface area between two segments at the joint location and certain surrounding zones. Consequently, a decrease in the inertial modulus and cross-sectional area at these sections of the lining ring is expected. A specific implementation was developed using a finite-element method framework in which an iterative procedure was applied with the height of the joint section as the unknown parameter. The results obtained using the new simplified HRM (SHRM) were compared with those obtained using the existing complex HRM, which takes joints directly into account, and a three-dimensional numerical model. The results obtained show that the SHRM can be used to estimate the behaviour of a segmental tunnel lining effectively. [ABSTRACT FROM AUTHOR]

This paper focuses on the evaluation standards of factor of safety for foundation stability analysis. The problem of foundation stability is analyzed via the methods of risk analysis of engineering structures and reliability-based design, and the factor of safety for foundation stability is determined by using bearing capacity safety-factor method (BSFM) and strength safety-factor method (SSFM). Based on a typical example, the admissible factors of safety were calibrated with a target reliability index specified in relevant standards. Two safety criteria and their standards of bearing capacity of foundation for these two methods (BSFM and SSFM) were established. The universality of the safety criteria and their standards for foundation reliability was verified based on the concept of the ratio of safety margin (RSM). [ABSTRACT FROM AUTHOR]