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The sustainable use of water reservoirs is threatened by sediment accumulation, but loss of storage volume can be prevented or limited by appropriate sediment management strategies that work in a variety of expected conditions. The development of a reservoir flushing strategy, tested against water and sediment inflow that might occur over centuries, is presented. A typical length of water and sediment records of 50 years was used to represent the range of variability within a year, and extended by deducing longer term inter-annual variability from suitable indicators (sediment cores in natural lakes, tree-ring chronologies etc.). It was concluded that, over past centuries, water inflows over a period of 50 years could typically vary by about 10%, while sediment inflows could vary by about 20%. The resilience of flushing rules derived solely on the recorded dataset over centuries-long periods was tested using a long-term computer simulation of reservoir sedimentation. The simulations showed that some modifications to the flushing rules would increase performance over centuries-long periods. Although the approach was derived for a specific project, it is based on some generally applicable parameters, such as the discharge at which operation stops and the moving average of the annual peak flow. [ABSTRACT FROM AUTHOR]

Squeezing is a well-known geotechnical phenomenon in the excavation of underground spaces, especially tunnels. Squeezing occurs under different geotechnical conditions in weak rock masses. A study was carried out to develop a mathematical and practical model to predict squeezing so that risk mitigation measures can be taken if necessary. A mathematical model based on a gene expression programming algorithm was developed using a database of 115 squeezing case histories. Four model performance evaluation criteria – specificity, sensitivity, accuracy and Matthew's correlation coefficient – and the receiver operating characteristic curve were then assessed based on a testing dataset. The accuracy of the model was also compared with that of previously developed models. Found to be able to determine squeezing with acceptable accuracy, the model was then used to investigate squeezing-prone areas in the Beheshtabad water-conveyance tunnel in Iran. [ABSTRACT FROM AUTHOR]

In the metamodelling-based Monte Carlo simulation (MCS) framework for reliability analysis of structures, the training samples used to construct the response surface should be as close to the failure plane as possible to ensure sufficient accuracy in reliability estimates. For this, an algorithm based on the maximin distance criterion combined with an error norm based on leave-one-out cross-validation (CV) is proposed to construct a moving least-squares based response surface for improved reliability estimate. The algorithm hinges on the fact that the MCS points having predicted responses less than the maximum absolute error obtained by the leave-one-out CV approach are likely to have the maximum effect on the accuracy of the reliability estimate. Relying on this, two points are added at each iteration, ensuring that the new data points are sufficiently close to the actual limit state and adequately far from existing data points. The improved reliability estimation capability of the proposed algorithm considering the direct MCS-based results as the benchmark is elucidated numerically by considering two example problems. [ABSTRACT FROM AUTHOR]

A passive shape-memory-alloy–rubber-bearing isolator has been developed for seismic protection of offshore jacket platforms. Mathematical modelling of an offshore jacket platform subjected to earthquake ground motions was undertaken, after which a systematic study of the key parameters of the isolator was undertaken to investigate its efficiency and to improve its performance. Dynamic time history analyses were carried out for both isolated and non-isolated jacket platforms using scaled ground motions. These clearly indicated the effectiveness of the isolator in controlling the overall responses of the jacket platform. It was better at mitigating structural displacement than structural acceleration, and its performance was dependent on the duration of ground motion. [ABSTRACT FROM AUTHOR]

The head–discharge relationship of an overflow weir is a prerequisite for flow measurement. Conventionally, it is determined by regression methods. With machine learning techniques, data-driven modelling becomes an alternative. However, a standalone model may be inadequate to generate satisfactory results, particularly for a complex system. With the intention of improving the performance of standard gene expression programming (GEP), a hybrid evolutionary scheme is proposed, which is coupled with grey system theory and probabilistic technique. As a gene filter, grey relational analysis (GRA) eliminates noise and simulated annealing (SA) reduces overfitting by optimising the gene weights. The proposed GEP-based model was developed and validated using experimental data of a submerged pivot weir. Compared with standalone GEP, the GRA–GEP–SA model was found to generate more accurate results. Its coefficients of determination and correlation were improved by 3.6% and 1.7%, respectively. The root mean square error was lowered by 24.8%, which is significant. The number of datasets with an error of less than 10% and 20% was increased by 15% and 12%, respectively. The proposed approach outperforms classic genetic programming and shows a comparative error level with the empirical formula. The hybrid procedure also provides a reference for applications in other hydraulic issues. [ABSTRACT FROM AUTHOR]

The shear strength of 14 reinforced concrete beams, all devoid of shear reinforcement, is experimentally investigated. An analytical model is also formulated, by introducing the three main resisting mechanisms in shear, based on the contributions of the concrete compressive zone, aggregate interlock along the inclined cracks and steel fibres (dowel action is neglected). Hooked-end steel fibres 35 mm and 60 mm long are used at volume fractions ranging from 0.75 to 1.5% in the former case, and from 0.5 to 1.0% in the latter case. In all, the shear capacity resulting from the tests is higher than that predicted by the lower bound limit proposed by G. Parra-Montesinos in 2006 and by American Concrete Institute and Indian standard building codes (ACI 318 and IS 456) for fibrous concrete beams. The efficacy of the proposed model is also compared with the 12 other models proposed in the literature. The contribution of shear-resisting mechanisms, namely, compressed concrete, aggregate interlock and steel fibre, is found to be approximately 67, 15 and 18%, respectively, of the total shear strength. The effect of fibre factor (F) and longitudinal reinforcement (ρ) on the contribution of various shear-resisting mechanisms have been rigorously studied and presented. [ABSTRACT FROM AUTHOR]

The evaluation of wave run-up on beaches is of significant importance since it is used in different coastal engineering and management applications, including the assessment of beach morphology, the determination of erosion and flooding risk, and the design and maintenance of coastal structures. The main aim of this paper is to present a new method of wave run-up prediction, which is intended to be applicable to the various types of natural beaches. A single formulation was established for beaches, which were categorised as dissipative, reflective and intermediate. This comprehensive parametric run-up model, which included both wave set-up and swash excursion, was specifically developed to represent the wide-ranging conditions experienced in the swash zone in terms of beach conditions. The run-up model included a means to account for obliquely incident waves, varying foreshore sediment characteristics and the infiltration/exfiltration processes during swash events; it also used fitting parameters to account for other site-specific conditions. The novel run-up model produced comparable results to other parametric models, and showed good correlation with laboratory data and limited field data. However, while the model was deemed suitable to be adopted at varying coastal sites, field data are required for implementation to yield meaningful output. [ABSTRACT FROM AUTHOR]

In this study, grading of surrounding rock was based on rock mass basic quality (BQ) according to Chinese specifications. A numerical approach was used to construct a synthetic rock mass model (SRMM) to represent the jointed rock mass and then obtain the strength of the rock mass. To construct a discrete fracture network, intact rock was represented by the bonded particle model and joint behaviour was represented by a smooth joint model. In a case study (Hongtuzhang tunnel), the micro properties of granite cores with different degrees of weathering were determined and the representative elementary volume of the surrounding rock was set as 15 × 15 m. Five slightly weathered, three slightly to moderately weathered and two moderately weathered granite surrounding rock mass models were established based on the probability distribution of joint sets in each borehole, and the conversion BQ value was acquired according to the calculated strength of the SRMM. The surrounding rock grades obtained using geological surveys were found to be higher than those predicted by the numerical method. The numerical calculation was consistent with actual excavation of rock mass at a borehole. [ABSTRACT FROM AUTHOR]

The focus of this paper is on the specific project of an underground pedestrian passage across the existing Middle Jiangdong Road in Nanjing, China. The reinforcement effect of the end soil of the rectangular pipe jacking is analysed. A three-factor and three-level soil reinforcement scheme is designed based on the principle of the orthogonal test. The slip instability theory is supplemented to improve the calculation of the stability coefficient of the reinforced soil, and the ground subsidence above the reinforced soil is calculated by using a numerical model. The optimal reinforcement scheme is determined and applied to the underground pedestrian passage engineering through direct analysis and variance analysis of the results of the orthogonal test. The rationality of the scheme is verified by analysing on-site monitoring and data. The research results serve as a guide in the construction of future rectangular pipe jacking, and the research methodology developed provides a reference for similar underground pedestrian passage projects. [ABSTRACT FROM AUTHOR]

This study contributes to emerging computationally efficient methods to account for multi-purpose reservoir operations at the dam design stage. In many cases, the water supply reliability objective introduces binary variables into an otherwise simpler linear programming (LP) formulation. This has led to widespread use of evolutionary methods such as particle swarm optimisation (PSO). Combining the branch and bound (BB) method with a hybrid PSO–LP, this study presents a new BB–PSO–LP algorithm to solve the joint design and operations problem. The proposed BB–PSO–LP algorithm was benchmarked against classical versions of the BB algorithm and PSO–LP. Superiority of the BB–PSO–LP algorithm was demonstrated by finding slightly better solutions in a shorter time. That said, PSO–LP also led to acceptable results in a similar time. Although the BB algorithm was found to be efficient in problem solving, under certain conditions it is difficult for the BB method to find a feasible solution. [ABSTRACT FROM AUTHOR]

Understanding of desiccation-induced cracking in soil has improved over the last 20–30 years through experimental studies, but progress in predictive modelling of desiccation cracking has been limited. The heterogeneous structure of soils and the multi-physics nature of the phenomenon, involving emergence and propagation of discontinuities, make the mathematical description and analysis a challenging task. The authors present a non-local hydro-mechanical model for soil desiccation cracking capable of predicting crack initiation and growth. The model is based on peridynamics (PD) theory. Attempts to model soil desiccation cracking by PD are limited to a purely mechanical description of the process that involves calibration of the parameters. In contrast, the model presented in this paper describes soil desiccation cracking as a hydro-mechanical problem, where moisture flow and deformation are coupled. This allows for investigating and explaining the mechanisms controlling the initiation and propagation of discontinuities. The model is applied and tested against two sets of experimental data to explain the typical features of drying-induced cracking of clays. The validations use experimental parameters (Young's modulus, water retention characteristics) and avoid calibrations to test the accuracy of the model. The correlations between the shrinkage of soil clay, changes in displacement fields and crack growth are demonstrated. Crack initiation, propagation and ultimate crack patterns simulated by the model are found to be in very good agreement with experimental observations. The results show that the model can capture realistically key hydraulic, mechanical and geometry effects on clay desiccation cracking. [ABSTRACT FROM AUTHOR]

Sustainable engineering design requires the joint consideration of technical, ecological, economic and social aspects in the provision of societal demands, such as water and energy supply. A growing number of concepts and methods for integrated assessment and sustainable design have been developed in recent decades and pose new challenges to the engineering profession. This paper proposes the use of system design concepts and methods to link engineering design to ecological and social–economic knowledge. This study expands the conventional functional analysis approach from systems engineering with a technical focus towards a more integrated perspective that allows for the joint consideration of technical, ecological and social–economic solutions in engineering design. Participatory systems thinking and system dynamics modelling are used for conceptual and preliminary system design by analysing the hierarchy and flows of functions to meet system requirements. The methodology consists of three steps: requirement analysis (step 1), functional organisation analysis (step 2) and functional flow analysis (step 3). An application of the methodology is provided using sustainable water management in Cyprus as an example. The results demonstrate the synergies and trade-offs between technical, ecological and social solutions in water management that provide important information for the subsequent detailed system design phase. [ABSTRACT FROM AUTHOR]

Modal analysis of concrete arch dam–reservoir–foundation rock systems is a challenging task. The complexities arise mainly due to computing mode shapes encountered when solving an eigenvalue problem with asymmetric generalized mass and stiffness matrices. Moreover, the problem becomes complicated when wave propagation is occurring due to the inclusion of water compressibility and foundation rock mass. In the present study, a computational tool is especially developed for this purpose. The theoretical background is explained initially. Subsequently, dynamic analysis of the Morrow Point arch dam–reservoir–foundation rock system is carried out with different values of reservoir bottom absorption coefficient. In addition, some of the modal characteristics of such systems, including resonant frequencies and natural periods, are discussed. The main objective is to perform these analyses by modal analysis. However, the direct method of analysis is also carried out in each case as a basis for comparison from the perspectives of accuracy and efficiency. [ABSTRACT FROM AUTHOR]

Open caisson shafts are a widely adopted solution for a range of geotechnical applications. An external 'cutting shoe' is a common construction feature used to reduce the soil frictional resistance acting on the caisson during sinking. This forms an annular void encircling the caisson which is filled with a support fluid to maintain excavation stability. The primary aim of this paper is to explore the influence of the cutting shoe geometry on the resulting vertical bearing resistance in sand. Finite-element limit analysis is adopted for this purpose. Additional parameters considered in the modelling include the roughness of the caisson cutting face and cutting shoe, and the caisson radius and embedment depth. The results show that the influence of the cutting shoe is highly dependent on the caisson cutting face roughness and the soil friction angle, illustrated using detailed soil failure mechanisms. The roughness of the cutting shoe is also shown to cause a significant increase in the vertical soil reaction for large caisson embedment depths. By way of example, a recent case study in the UK, involving the construction of a 32 m dia. caisson, is used to highlight the potential influence of the cutting shoe on the bearing resistance during caisson sinking. [ABSTRACT FROM AUTHOR]

The gradation of rockfill affects creep behaviour, but indoor testing apparatus does not allow a field maximum particle size of the rockfill of 1000 mm. To investigate the creep behaviour of rockfill with different maximum particle sizes and establish a creep model for the rockfill material, oedometer creep tests for slate rockfill material with different maximum particle sizes were conducted to explore the effect of gradation on the creep behaviour of rockfill materials. The test results showed that the creep strain increases and the rate of increase decreases with the increase in vertical stress. The creep strain increases with the decrease in maximum particle size under all vertical stresses. Furthermore, a particle size ratio Rd was defined to establish the creep model. An empirical creep model was proposed to calculate the creep strain for rockfill with oversized particles that are not allowed by the experimental apparatus. Three groups of test data were used to determine the model parameters, and one group of test data was used to verify the predictive capacity of the model. The results showed that the model can satisfactorily predict the creep behaviour of slate rockfill with oversized particles. [ABSTRACT FROM AUTHOR]

Cold-formed steel members are usually used as purlins in buildings to support roof cladding and thus they can be treated as beams restrained fully or partially in the lateral and torsional directions. However, when these beams are subjected to wind suction loading, their free flange is in compression, which may cause web–flange distortional buckling (WFDB). This paper presents an analytical study on the WFDB of zed-section purlins when subjected to uplift bending. A simplified model is proposed to describe the WFDB of partially restrained purlins, from which the formula for calculating the critical stress of the WFDB is derived. The present model is validated by the results obtained from the finite strip analysis. [ABSTRACT FROM AUTHOR]

This paper investigates an integrated quay crane (QC)–shuttle vehicle (SV) scheduling problem (SP) with capacitated apron buffer, which is subject to practical constraints on non-zero travelling time, precedence relationships between container-handling jobs, QC non-interference, safety margin, blocking and apron buffer capacity. The objective is to minimise the makespan of vessel handling by simultaneous optimisation of bay-to-QC assignment, the sequences of bays handled by QCs, the sequences of jobs handled by QCs, job-to-SV assignment and the sequences of jobs handled by SVs. To achieve this, a mixed-integer linear programming model is first formulated to solve the SP. The relationships of decision variables and model constraints are then analysed to generate two sub-models: assignment based and sequence based. The former sub-model is developed from the proposed model by pre-determining the assignment of bay-to-QC and job-to-SV, and the latter is developed from the proposed model by pre-determining the sequences of jobs handled by each QC and each SV. Hybrid genetic algorithms with the two sub-models are proposed for numerical experiments. Practical implications of this investigation for apron buffer zone design are discussed. [ABSTRACT FROM AUTHOR]

An approximate method for non-linear seismic analysis of three-dimensional two-way asymmetric buildings resting on flexible foundations under bi-directional ground motions is presented. To take into account the soil–structure interface effect, the sub-structuring method with frequency-independent soil springs and dashpots was employed. To consider the non-linear behaviour of the structure, a modal stick with five degrees of freedom was used to simulate the multi-degree-of-freedom modal equations for the soil–structure system. Using the bifurcation characteristic of modal pushover curves, the modal stick was modified, by which the coupled modal non-linear translation and rotation deformations were simulated. The seismic responses of two flexibly supported asymmetric buildings (three and eight storeys) were evaluated by the uncoupled modal response history analysis (UMRHA) method employing the proposed modal stick. The seismic responses of the structures were also obtained by employing the rigorous non-linear response history analysis and the results were compared with the corresponding outcomes from UMRHA method. The comparison showed good agreement between the outcomes of the two analysis methods, thus demonstrating that the proposed three-dimensional non-linear analysis technique developed in this study is an effective and applicable tool for dealing with the non-linear analysis of flexibly supported two-way asymmetric-plan structures. [ABSTRACT FROM AUTHOR]

Over recent decades the chemical stabilisation technique has been applied with success in many transportation geotechnics applications. However, the development of chemical stabilisation techniques requires the efficient extraction of critical information from experimental trials and their integration in accurate and robust predictive modelling frameworks to be used by practitioners. This is the case for cement-based stabilisation technology for soft soils, where binder quantity (b), water content (w) and the curing time (t), play a key role in the final soil's geomechanical properties, namely the unconfined compressive strength (qu) and the undrained secant Young's modulus at 50% of qu (Eu50). This work presents an integrated optimal experimental design and advanced modelling approach that minimises the experimental costs and derives generalisable models (qu against b and Eu50 against b) for the conditions of interest (w and t). The proposed framework is instrumental for engineers to define the necessary processing conditions to apply when stabilising a given soil and is very efficient with respect to the experimental effort and costs required. [ABSTRACT FROM AUTHOR]

The bonding between basalt fibre-reinforced polymer (BFRP) and concrete has a crucial effect on the durability of externally retrofitted concrete structures, because the BFRP–concrete interface is the element most vulnerable to failure. Although numerous experiments have investigated the tensile bonding strength of the FRP–concrete interface, there have been only a limited number of numerical simulations of crack propagation. Therefore, in this study, the tensile bonding strength between BFRP and concrete was analysed numerically using a cohesive zone model (CZM). To validate the numerical modelling results, experiments were conducted under different initial crack widths. To clarify the crack propagation, the representative fracture area technique was applied. According to the numerical and experimental results, the CZM is appropriate for simulating the BFRP–concrete interface. The results also indicate that specimens with no initial cracks suffer only limited cracking at the edge of the surface, whereas the specimen with an initial 10 mm crack width suffered cracking across almost all of its surface. This is due to the reduced effective bonding area of the BFRP–concrete interface. [ABSTRACT FROM AUTHOR]

The effectiveness of some of the most commonly used models for predicting the bond strength of steel and glass-fibre-reinforced polymer reinforcing bars in normal-strength concrete (NSC) and high-strength concrete (HSC) was examined. To this end, a comprehensive database of published results on pullout specimens was collected. A non-linear least-squares fitting method was used to formulate simple and accurate models with a unified structure for both steel- and fibreglass-reinforced specimens. To investigate the efficiency of the proposed model for NSC, the results of specimens in the literature, which were not included in the model construction, were used. However, due to the scarcity of HSC bond specimens compared with NSC specimens, an experimental programme was conducted for model verification. The final results revealed that the simple equations developed in this study were capable of accurately predicting the bond strength of steel and polymer rebars in both NSC and HSC. [ABSTRACT FROM AUTHOR]

In the past, several experimental and theoretical studies have been carried out to evaluate the ultimate bearing capacity (UBC) of geosynthetic-reinforced sandy soil foundations (GRSSFs). The experimental studies consist of model footing load tests which are expensive and time consuming whereas the results obtained by theoretical expressions often lack consistency. In the study reported in this paper, a cost-effective, extreme learning machine (ELM) model was used for the first time to obtain a more realistic prediction of the UBC of a GRSSF. A large dataset consisting of actual field and laboratory measurements of UBC was used to develop and validate the model. Its predictive performance was then compared against robust machine learning regression models and traditional theoretical methods. The study shows that the proposed model is useful and attains an adequate level of accuracy in predicting the UBC of GRSSFs when compared with other data-driven models and some traditional methods. The research also shows that the ELM technique is a realistic and reliable approach that could be employed in geotechnical engineering intelligent systems for the prediction of multivariate non-linear problems. [ABSTRACT FROM AUTHOR]

The aim of the research reported in this paper was to evaluate the recommendations commonly used for limiting the deformations of segmental reinforced concrete tunnels built in soft soil. These traditional deformation limits are empirical and do not consider the slenderness ratio or soil-pressure distribution around tunnels. Furthermore, while they are generally assumed to relate to the serviceability limit state, this is not clear. Parametric analyses were therefore performed by means of finite-element models in which the non-linear behaviour of joints and materials was taken in account. The serviceability deformation was defined to prevent typical problems that could jeopardise the serviceability states of segmental linings. These serviceability deformations were then compared with traditional deformation limits. The results showed that the serviceability deformation depends on the slenderness ratio and the soil-pressure distribution. It was concluded that empirical recommendations are only suitable for certain slenderness ratios and soil-pressure distributions. [ABSTRACT FROM AUTHOR]

This paper investigates the dynamic recovery policies for liner shipping services with the consideration of buffer time allocation and uncertainties. The aim of this study was to allocate the buffer time at the tactical level and then determine optimal options of actions, including speed optimisation strategy, port skipping and acceleration rate choice, for recovering from disruptions due to various uncertainties or random adverse events, which cause vessel delays. To achieve this, an attempt was made to obtain the optimal balance among economic, environmental and service reliability objectives. A novel mathematical formulation is introduced to solve the robust vessel scheduling problem with short- and long-term decisions. Furthermore, two heuristics were tested to solve the proposed model. Experiments on a container liner shipping service showed the validity of the model and a set of managerial insights were gained from them. [ABSTRACT FROM AUTHOR]

This study achieved three goals to clarify the impact of a vegetation patch on flow adjustment and velocity. First, a valid equation for the interior adjustment distance (Ld) inside a model patch was developed for a wide range of velocities and flow depths. Second, the minimum distance inside a patch beyond which the resuspension of fine sediment is suppressed (Lmin) was found to be related to the position at which the local velocity decreases to the threshold for generating stem-scale turbulence. Lmin primarily depends on the flow blockage (Cdab) and the stem diameter (d): a shorter Lmin is a result of a larger Cdab and a smaller d. An equation was formulated for estimating Lmin. Third, for the fully developed flow region inside a patch (L > x > Ld), an equation was developed to estimate the increase in the mean velocity in the bare channel relative to the overall mean channel velocity. For Cdab < 2, this fraction is controlled by both the patch density (ad) and the patch blockage (b/B) whereas, for Cdab > 2, this fraction is controlled by only b/B. A suggestion for choosing the patch size in future flow and sediment research projects is presented. [ABSTRACT FROM AUTHOR]

The use of fibre-reinforced polymers (FRPs) as internal confining reinforcement in combination with longitudinal steel bars in concrete compression members provides significantly improved strength, ductility and durability. To date, only a few experimental studies have been carried out to establish the compressive behaviour of concrete columns longitudinally reinforced with steel bars and confined with FRP ties. This paper provides a confinement model with several expressions for predicting the axial stress–strain response of hybrid-reinforced (i.e. longitudinal steel bars combined with FRP ties) square concrete columns under axial compression loading. The model considers the influences of several test parameters, such as the configuration, size, volumetric ratio, spacing and type of ties (FRP pultruded bar ties and closed-type wound rectangular-section ties). The proposed model predicted well the peak and ultimate strength and strains compared with existing models. The overall accuracy of the model was also assessed against selected test stress–strain responses. [ABSTRACT FROM AUTHOR]

In a hybrid simulation, a structure is divided into numerical and physical substructures in order to obtain more accurate responses in comparison to a full computational analysis. It is more computationally efficient to test complicated parts physically and model the remaining parts using a standard finite-element program. However, due to a lack of test facilities (for example due to specimen size, capacity of the hydraulic power pack, limitations of reaction frames and walls, and the number and capacity of actuators) and budget limitations, only a few substructures can be tested experimentally and the others have to be modelled numerically. Here, a new framework for hybrid simulation is introduced, which uses well-trained neural networks instead of physical substructures. This new framework is called a neuro-hybrid simulation (NHS). With the aim of overcoming the limitations of hybrid simulations (the need for numerous substructures, errors arising from the test setup, data acquisition, simultaneous interaction of experimental and numerical parts and so on), an initially trained Prandtl neural network is used to act as a virtual physical substructure. The proposed NHS was verified with some numerical examples, based on which the capability and accuracy of the framework was proven. [ABSTRACT FROM AUTHOR]

Since the major flood event in 2007, RPS has been deeply involved in investigating, understanding and reducing flood risk across the Hull and Haltemprice catchment. RPS has developed and refined a complex integrated catchment model by combining Yorkshire Water's model of below-ground assets with data for the watercourses and overland flow paths obtained from the Environment Agency, East Riding of Yorkshire Council and Hull City Council. RPS used the model to identify major schemes, leading to the design of flood alleviation schemes at Willerby and Derringham, Anlaby and East Ella, and Cottingham and Orchard Park. With further enhancements, the model has been used to better understanding of the complex interactions between the various water systems and solutions are being identified for a long-term plan. Hull has many unique features, driven by its topography, geology and the historical developments of its sewerage network and waterways. These specific challenges require bespoke solutions and there is a clear desire among the partner organisations to work together to drive contemporary blue–green solutions. This requires multi-agency working and progressive thinking to deliver effective flood risk management. This paper reviews the challenges in understanding and resolving these issues. [ABSTRACT FROM AUTHOR]

A new normal plane constraint for assessing the geometric non-linear behaviour of structures is proposed. In this procedure, the vector passing through a point placed on the equilibrium path and the iteration point is perpendicular to the locus of the iterative points. The capability of the suggested constraint equation was investigated numerically. To compare its abilities with other well-known techniques (the normal plane, cylindrical arc-length and updated normal plane methods), several planar and space trusses, plate and shells were analysed. The results proved the high accuracy and efficiency of the developed scheme. The powers of the methods in passing the limit points were also investigated. In addition, to assess the capabilities of the methods more accurately, they were all ranked based on the total number of increments and iterations required. [ABSTRACT FROM AUTHOR]

Berthing structures are constructed in coastal areas to accommodate the berthing and mooring of vessels. Tie rod anchors are provided in such structures in order to improve their performance and reduce deflection of the structure. In this study, various types of berthing structures (open and closed) were analysed with and without tie rod anchors. This paper presents the experimental results and their validation with numerical and analytical values. Further parametric studies were carried out to analyse the effect of tie rod anchors. The results imply that there is a considerable effect on the depth of fixity of the piles in open-type berthing structures when tie rod anchors are provided, whereas there is not much effect in closed-type berthing structures when tie rod anchors are provided. [ABSTRACT FROM AUTHOR]

This paper presents the application of hydraulic modelling for the prediction of pipe bursts in a water distribution system (WDS). As a case study, more than 1430 km of pipelines within 29 water pressure zones (PZs) in Bendigo and Castlemaine WDSs, located in Victoria, Australia, were modelled and calibrated using an InfoWorks WS hydraulic model. A pressure index (PI) was defined to quantify the intensity of high pressures in the WDS pipes. The PIs for all the PZs were calculated using hydraulic model simulations. Ten years of actual pipe burst data (2007–2017) in the studied WDSs were used in the research. A burst index (BI) was used to measure the burst rate for the length of pipe network within the study area. A mathematical relationship between PI and BI was proposed based on the first eight years (2007–2015) of burst data and the results of the hydraulic modelling in the same period. The number of pipe bursts for the last two years (2016–2017) in each PZ was then predicted according to the proposed mathematical relationship. The predicted number of bursts fitted well with the actual recorded pipe burst data, with a coefficient of determination of 0.98. [ABSTRACT FROM AUTHOR]

Herein a discrete-element model of a full-scale compound mesh barrier, formed by interweaved double-twist hexagonal meshes and strand rope square meshes is presented. A plastic hardening model is employed to investigate the energy dissipation terms within the barrier. The computational effort required for model initialisation is reduced through a novel generation procedure. The effect of different impact positions on the energy dissipation within the barrier and the way the impact load is transmitted to the main structural elements of the barrier are investigated through a sensitivity analysis. The results show that the impact position has both qualitative and quantitative effects on the barrier response, which significantly modify the peak load acting on the structural elements and the combination of shear, tensile and moment loading on the fence posts. [ABSTRACT FROM AUTHOR]

Landslides are major natural hazards that can pose significant risks to human lives and properties in mountainous areas. Mobility assessments of landslide debris are integral to the management of landslide risks. Over the past two decades, the Geotechnical Engineering Office (GEO) in Hong Kong has expended considerable effort on the development of debris mobility models, and a suite of advanced numerical tools has been developed using different numerical techniques, including particle-in-cell, smoothed particle hydrodynamics and arbitrary Lagrangian–Eulerian methods. The accuracy of the tools was corroborated against historical landslides in Hong Kong and typical values of model parameters were established for use in routine practice. These numerical tools offer geotechnical practitioners a pragmatic and efficient approach to assess the dynamics of landslide debris in landslide hazard investigations and quantitative risk assessments. Some of the numerical tools recently developed by the GEO can also be used to assess the dynamic interaction between landslide debris and structural countermeasures, thereby allowing design optimisation. This paper presents a holistic review of the technical development and engineering applications of these numerical tools with a focus on their roles in landslide risk management in Hong Kong. It also documents the experience of Hong Kong in steering and promoting the use of numerical modelling of large ground mass deformations for the purposes of slope safety management. [ABSTRACT FROM AUTHOR]

To conduct landslide risk assessment and assess the consequences of dam and levee failures, it is important to understand the overall failure evolution process that ranges from small-strain initiation to large-strain post-failure runout. To achieve this goal and simulate such landslide events, emerging large-strain numerical approaches, such as the material point method (MPM), show promising potential as tools to model the entire instability mechanism. While successfully incorporating multi-phase interactions in granular porous media. Soil–water interaction in unsaturated soils is critical when dynamic hydraulic loads act on levees, such as when the fluvial upstream water levels oscillate and in episodes of heavy rainfall infiltration. Recently, MPM has been successfully used in many geotechnical engineering applications, which in turn motivated further advancements of multi-phase formulations. This study presents an application of a novel single-point two-phase MPM formulation to model unsaturated soils subjected to transient hydraulic boundary conditions. The potential of this approach is discussed by analysing a large-scale slope failure experiment. Results are compared with the finite-element method and limit equilibrium method. It is concluded that similar results are obtained at small strains, but MPM allows the post-failure behaviour to be estimated, which is essential for risk management. [ABSTRACT FROM AUTHOR]

A large-strain consolidation model incorporating vacuum pressure growth propagation (VPGP) under vacuum preloading is proposed. A finite-difference method was developed to predict the vacuum consolidation behaviour. The proposed model can be degenerated into the existing model when the vacuum pressure growth factor reaches 10/day. The rationality of the proposed model was verified and compared with experimental results. The effect of VPGP on the consolidation behaviour of two typical soils was then analysed. A growth in vacuum pressure has a significant effect on consolidation, especially for a growth factor in the range 0–0.5/day. The radial and vertical propagation of vacuum pressure obviously slowed down the dissipation of excess pore-water pressure (EPWP). The maximum difference reached 48% and 37.5% when the radial attenuation factor and the vertical residual factor were in the range 0–0.1/cm and 0.25–1.00, respectively. The maximum value of the EPWP difference of two typical soils reached 65 kPa. [ABSTRACT FROM AUTHOR]

Concrete face rockfill dams are widely used in hydropower engineering because of their many advantages. As important structures, if the performance of the concrete face slab and the impervious curtain is weakened, leakages and even serious dam failures can occur. Based on an equivalent quasi-continuum medium model, three-dimensional finite-element numerical simulations of the seepage behaviour of Miaojiaba dam, China, are performed. The seepage field and seepage characteristics, including the phreatic line, maximum hydraulic gradient and seepage discharge, are analysed quantitatively and systematically under various abnormal conditions. The results show that cracks in different areas of the face slab and different degrees of degradation in the impervious curtain influence the seepage field in different ways, with cracks in the lower face slab being the most serious. Ensuring that the face slab and impervious curtain are working as intended is very important for the integrity of the dam. Therefore, the design and construction quality of impervious structures should be strictly controlled. Under abnormal conditions, seepage control should be realised to ensure the safety and stability of concrete face rockfill dams. [ABSTRACT FROM AUTHOR]

A large number of multi-reservoir hydropower systems are in operation all over the world in order to meet increasing power demand. To date, different optimisation methods have been applied to multi-reservoir systems. However, overcoming the computational effort required to find an optimal operating policy for multi-reservoir systems still remains a difficult task. The aim of this study was to optimise the operation of complex multi-reservoir hydropower systems using profust reliability – a theory used in the reliability analysis of manufactured systems. The profust-reliability-based optimisation model was applied to a system with reservoirs connected in series and parallel to determine monthly operating policies for synthetically generated streamflow. The results show that the model is applicable to multi-reservoir systems. [ABSTRACT FROM AUTHOR]

The aim of this paper is to present a modification of the trip distribution model and compare it with the traditional gravitational model, as well as with other models based on intervening opportunities. This modification can better represent the questions of variation of land use represented by the labour supply. The proposal uses two geometric shapes to define the intervening opportunities (circle and ellipse), and a new technique was tested to define these opportunities. The study was carried out with data on mobility in the city of Rio de Janeiro, Brazil and the results obtained are presented through descriptive statistics and graphical analysis. The main conclusions are that both geometric figures can be used to define the intervening opportunities and the modification in the proposed model is suitable to be applied to trip distribution. [ABSTRACT FROM AUTHOR]

Circular tunnels are the most popular shapes in urban underground transportation systems when mechanised tunnelling is used for the tunnel excavation. However, circular tunnels have a small space utilisation ratio. With materials development, non-circular tunnels are now common as their cross-section allows for an improvement in the efficiency of usage of underground space. In this work, the influence of tunnel shape on the lining forces was evaluated by using the hyperstatic reaction method (HRM). The internal forces derived using the HRM model were then compared with the results of a numerical model (Plaxis2D). A constant soil Young's modulus was adopted in both models. A parametric study was performed in order to assess the effect of parameters such as the Young's modulus of the soil, the lateral earth pressure coefficient, the tunnel lining thickness and tunnel depth on the structural forces produced in the tunnel lining. [ABSTRACT FROM AUTHOR]

A new approach for finding a cost-effective combination of groynes in a channel bend for the prevention of bend scour is presented. A linked simulation–optimisation model is proposed for this purpose. The morphological flow simulation model was developed by solving the shallow-water equations and the Exner sediment continuity equation in a boundary-fitted coordinate system. The optimisation model was developed utilising a binary-coded genetic algorithm. The proposed model can automatically provide a cost-effective groyne series in terms of their number, length and position in any vulnerable channel bend. A constraint in terms of bend scour is also incorporated in the optimisation model, which allows the optimisation model to obtain the best groyne combination for no bend scour. To appraise the performance of the model, it was applied to a hypothetical vulnerable channel bend. The model produced the minimised cost of installation of the groyne system at that location, at the same time as making the location free from bend scour. [ABSTRACT FROM AUTHOR]

The progressive collapse resistance of reinforced concrete (RC) frames in which a middle column has been removed has been investigated by many researchers. However, previous experimental and computational studies have focused mainly on the catenary action provided by longitudinal reinforcement in the beams spanning the missing column. This study investigated the contribution of infill walls. Finite-element analysis was used after calibrating a reference model using test results reported by other researchers. Models were developed for a RC frame with and without infill walls. An equivalent strut was used in the infill walls to allow the removed column load to be transferred through the struts instead of developing catenary action in the beams. A simplified model of the progressive collapse resistance of frames with infill walls was then derived to estimate the peak strength provided by the infill wall under the scenario of middle-column removal. [ABSTRACT FROM AUTHOR]

The use of stabilising piles is an effective method of reinforcing a slope against landslides. Soil arching between the piles promotes more load transfer into the piles, thus improving slope safety. However, few analytical solutions have been proposed for assessing the safety of an anisotropic slope with soil arching between stabilising piles, especially in most current design procedures. Based on BS 8006-1:2010, an analytical method was developed to evaluate the stability of a slope reinforced with stabilising piles, taking the anisotropy of soil strength and the horizontal soil-arching effect into account. A field case was used to assess the results of the proposed analytical method; differences of approximately 0·6–8·9% were found. To validate the proposed analytical method, a three-dimensional numerical simulation considering soil anisotropy was conducted; variation of the soil cohesion with depth and the direction of principal stress was introduced into the numerical analysis. The safety factors predicted by the numerical simulation agreed well with those derived by the proposed analytical method, with differences of 0·7–17%. The safety factor was found to decrease with increasing anisotropy coefficient and increase with higher effective cohesion and effective friction angle. [ABSTRACT FROM AUTHOR]

Estimation of streamwise depth-averaged velocity and boundary shear stress are important requisites for modelling of river flows associated with flood events. Recently, many methods have emerged to predict these flow variables with great accuracy, but they provide unsatisfactory results in shear layer regions. This paper presents an improved methodology to predict depth-averaged velocity and bed shear stress for a straight compound channel flow. An analytical solution to the depth-integrated turbulent form of the Navier–Stokes equation is obtained. The transverse shear stress in the mixing region is modelled using an effective eddy viscosity concept that contains horizontal coherent structures and three-dimensional bottom turbulence. The secondary flow term is modelled by considering the log-law profile for streamwise velocity and half cosine curve for the transverse velocity component. The analytical solution is successfully applied to a wide range of experimental compound channels and field cases. The efficacy of the present solution has been successfully tested by comparing with observed values. [ABSTRACT FROM AUTHOR]

Historical un-reinforced masonry (URM) buildings in Egypt from the medieval period generally comprise timber tie-rods that link the arches of arcades at the top of the column heads and along the arcade plane (in-plane). Usually, additional tie-rods are found perpendicular to the arcades (out-of-plane). Timber ties can also be used between facing tall URM bearing walls to minimise their buckling vulnerability. They play a considerable role in resisting seismic forces and minimising the deficiencies of URM buildings. A limited experimental investigation and a wide analytical campaign were conducted on two model buildings with the prevailing dimensions and materials of historical medieval buildings in Cairo by employing finite-element three-dimensional modelling. The focus of the work was the roles timber tie-rods play in the seismic stability of parallel-arcaded and cross-arcaded URM historical buildings. A proposal for enhancement of the seismic resistance of parallel-arcaded systems using a steel bracing system is provided. [ABSTRACT FROM AUTHOR]

This paper deals with the modelling of sand–structure interface behaviour under monotonic loading. In particular, the importance of the stress–dilatancy relationship is highlighted since volumetric behaviour strongly characterises the variation of the normal stress in constant normal stiffness direct shear tests. The procedure for the calibration of constitutive parameters is shown and the model is validated by comparison with different sets of sand–aluminium interface direct shear tests. [ABSTRACT FROM AUTHOR]

This paper describes the dynamic behaviour of offshore structures modelled as discrete dynamic systems with the installation of innovative smart-tuned liquid column dampers (TLCDs). The use of advanced nano-fluids enhances the mechanical properties of the TLCD and allows the conventional passive system to be modified into a semi-active damping system. The magnetic force is modelled as an additional non-linear stiffness applied on the main structure once the magnetic field is activated. This new approach brings novel perspectives in reducing structural vibrations with respect to conventional TLCD systems. The aim of the study is to present a numerical investigation of the parameters involved in the dynamic behaviour of these systems subjected to random forces. In particular, a comprehensive analysis of a simplified structural model as a two-degrees-of-freedom system is given. Mathematical details and procedures using magneto-rheological-TLCD dampers without the need for commercial frameworks are presented. The present coupled system of ordinary differential equations is solved in a Matlab environment by using the built-in Runge–Kutta implementations for the solution of non-linear equations. This allows engineers and designers to obtain an initial estimation of the structural behaviour prior to in-depth simulations and analysis. [ABSTRACT FROM AUTHOR]

This paper demonstrates the influence of differential roughness on the boundary shear distribution for compound open channels. A mathematical relationship is derived between the percentage shear force carried by floodplains and five non-dimensional parameters (width ratio, relative flow depth, relative roughness, Reynolds number and Froude number). A procedure for assessing the flow distribution in terms of zonal boundary shear distribution and momentum transfer coefficients at the junction of a compound channel is presented. The efficiency of the model was tested by comparisons with published datasets and large experimental flood channel facility datasets. Compared with other standard approaches, the proposed method provided the least error in the predictions of both boundary shear and flow. The approach was also verified using actual river data and was found to provide good predictions in real-world applications. [ABSTRACT FROM AUTHOR]

For many remote and under-privileged communities, water filtration is the first step of treatments before boiling and/or other higher level treatments. Clogging is a common unavoidable hindrance to such systems, which causes reduced efficiency with regard to the flow rate of filtered water. Backwashing is commonly used to recover the filtration capacity of clogged filter media. This paper presents an improvement of a previously developed simple clogging and backwashing efficiency model for the third-generation IHE family filter, which was developed by Unesco-IHE Institute for Water Education. The earlier simple model considered a linear decay of flow rate due to clogging in a weekly timestep. With the aim of enhancing the model's accuracy, this work considered three other models (a linear model with a daily timestep, a power function model and an exponential model). The performance of the models was assessed using the root mean squared error and chi-squared (χ2) values derived from predicted and measured flow rates through the device during successive clogging and backwashing periods for up to 4 months. The improvements using the linear 1 day model over the linear 7 day model were insignificant. Among the tested models, the power function model provided the best predictions, with an average χ2 improvement of 33% over the previously developed linear model. [ABSTRACT FROM AUTHOR]

Combined weir–gate structures are important structures for controlling the water level, measuring discharge and avoiding sediment deposition behind a weir. They can be used, for example, in irrigation channels and waste water systems. Using three-dimensional numerical software (Flow-3D) and experimental data from the literature, four combined systems of a triangular weir and a rectangular gate with different geometries were simulated. Dimensional analyses were then performed to determine the dimensionless parameters that affect the discharge coefficient of such structures. Four different intelligent system models were used to estimate the discharge coefficient and their results were compared. It was found that Flow-3D is highly capable of simulating the flow over a combined structure. Goodness of fit criteria also showed that the numerical solver estimated the water head and discharge coefficient very well. The results of all the models showed that the discharge coefficient had an inverse relation with the dimensionless parameters h/b, h/d and h/y (h being the water head over the weir, b the gate width, d the gate height and y the distance between the bottom of the weir and above the gate); the discharge coefficients were 0·3–0·9. Accuracy analyses of six intelligent system models showed that the multi-layer perceptron model was the superior model, followed by the M5P model, the regression equation, the radial basis function and the generalised regression neural network model. [ABSTRACT FROM AUTHOR]