Using the scaled boundary finite element method to model 2D time-dependent geotechnical engineering problems

The scaled boundary finite element method caters well for soil-structure interaction problems, but the formulation does not cater for the presence of changing pore pressures with time, body loads and tractions. A detailed formulation is presented in this paper to consider the general 2D analysis case for modelling coupled consolidation, accounting for body forces and surface tractions in both the bounded and unbounded media. The advantages of this method compared to conventional methods are also explained in this paper

Simulation of weather-driven deterioration of clay embankments

Clay embankments used for road, rail, and flood defense infrastructure experience several weather-driven deterioration processes that lead to a progressive degradation in their hydromechanical performance. This paper presents a numerical modeling approach that accounts for the development of desiccation cracking in clay embankments. Specifically, a bimodal soil water retentivity model was adopted to capture the long-term hydraulic behavior of clay embankments prone to weather-driven desiccation cracking. A numerical model was developed for a heavily instrumented and monitored full-scale research embankment with long-term field data. The model was able to capture the variation of near-surface soil moisture and matric suction over a monitored period of nine years in response to weather cycles. The developed and validated numerical modeling approach enables forecasting of the long-term performance of clay embankments under a range of future climate scenarios

Development of a Fuzzy System for Change Prediction in Construction Projects

Change management has been the focus of different IT systems. These IT systems were developed to represent design information, record design rationale, facilitate design coordination and changes. They are largely based on managing reactive changes, particularly design changes, in which changes are recorded and then propagated to the relevant project members. However, proactive changes are hardly dealt with in IT systems. Proactive changes require estimating the likelihood of occurrence of a change event as well as estimating the degree of change impacts on project parameters. Changes in construction projects often result from the uncertainty associated with the imprecise and vague knowledge of much project information at the early stages of projects. This is a major outcome of the case studies carried out as part of this research. Therefore, the proposed model considers that incomplete knowledge and certain project characteristics are always behind change causes. For proactive changes, predicting a change event is the main task for modelling. The prediction model should strive to integrate these main elements: 1) project characteristics that lead to change 2) causes of change, 3) the likelihood of change occurrence, and 4) the change consequences. It should also define the dependency relationships between these elements. However, limited data (documented) are only available from previous projects for change cases and many of the above elements can only be expressed in linguistic terms. This means that the model will simulate the uncertainty and subjectivity associated with these sets of elements. Therefore, a fuzzy model is proposed in this research to capture these elements. The model analyses the impact of each set of elements on the other by assigning fuzzy values for these elements that express the uncertainty and subjectivity of their impact. The main aim is to predict change events and evaluate change effects on project parameters. The fuzzy model described above was developed in an IT system for operational purposes and was designed as a Java package of components with their supporting classes, beans, and files. This paper describes the development and the architecture of the proposed IT system to achieve these requirements. The system is intended to help project teams in dealing with change causes and then the change consequences in construction projects

Computational analysis of energy and cost efficient retrofitting measures for the French house

Energy-efficient housing has become a mandatory aim to address climate change. This paper presents a computational analysis taking a French single family house as a case study, and aims to investigate both energy and cost-efficiency of market available retrofit measures using dynamic thermal modelling. A parametric analysis tool was developed to run automated batch-simulations using EnergyPlus simulation engine and to calculate the cost associated with retrofit measures, at each simulation run. The automated simulations are carried out, using an exhaustive search technique, for all permutations of measures. These included different building fabrics, ventilation strategies, levels of air-tightness and 5 different heating systems for 4 main climatic regions of France (7680 variants for each of the 4 climatic region). In this analysis, an optimization problem is set to minimise the delivered energy and retrofitting investment cost subject to an energy-saving minimum limit, payback criterion, and summer overheating-risk. The results showed optimum solutions with different fabric and system retrofit combinations that varied in numbers for the different climatic zones. The upper bound of optimum investment cost varied from 80 to 290 €/m2 for Nice and Paris, respectively

The behaviour of metal contaminants in silty sand and gravel

An investigative study is reported to determine the behaviour of metal contaminants in silty sand and gravel. A soil box experiment was conducted with a silty sand of permeability, k = 3.9242x10-5 m/s. The sand was placed on a bedding of 6 mm peagravel, inside the test box. Copper Nitrate, Chromium Nitrate, Nickel Sulphate and Lead Nitrate were dissolved, mixed with RO (reverse osmosis) water for use in four separate experiments. Column tests were conducted with the same silty sand and gravel and under similar experimental conditions. Copper flushing was very slow, it was strongly absorbed to the silty sand and gravel. Chromium was entirely retained (34mg/Kg) within the experimental system, and its released concentrations were very low. Nickel was shown to have a good aqueous solubility thus it was freely mobile in the sand. There was some minor adsorption of Nickel though lower than that of Copper and Chromium

ACHILLES Reading Guide 3: Asset scale deterioration

The deterioration of earthworks reduces theirserviceable performance and increases thelikelihood of instability. This can havesignificant impacts on the safe and reliableoperation of the transportation networks thatthey support. These deterioration processesare weather-driven and may lead to failuremany years after construction even in theabsence of increased mechanical loads.Evidence also indicates that climate changewill increase rates of asset deterioration andreduce time to failure. This documentsummarises the key conclusions on assetdeterioration drawn from the ACHILLES bodyof work. A more detailed overview of theACHILLES concept can be found in ReadingGuide 1 [1], the project website (achilles-grant.org.uk), and the following papers: [2,3]

Emulating long-term weather-driven transportation earthworks deterioration models to support asset management

The deterioration of transport infrastructure earthworks is a global problem, with negative impacts for infrastructure resilience, becoming of increasing significance as existing infrastructure ages. Key mechanisms which affect this deterioration include seasonal pore pressure cycling driven by changing weather and climate, and the long-term dissipation of construction induced excess pore pressures. These complex processes lead to significant uncertainty in rates of deterioration and the current state of existing earthworks assets. The objective in this work was to establish a framework to emulate deterministic numerical models of slope deterioration over time using statistical (Gaussian process) emulation. A validated, physically based, deterministic modeling capability has been developed that can replicate the hydro-mechanically coupled behavior of cut and embankment slopes and their deterioration as driven by weather and climate. In parallel, a statistical (Gaussian process) emulator model was developed, and then trained with data from a deterministic modeling parametric study, using a formal experimental design approach, making use of Latin hypercube sampling. Exemplar forecasting outputs are presented to demonstrate application of the approach for use in decision-making. This information can be used in the design of new earthworks and the management of existing earthwork portfolio