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Shakedown limit has been perceived as a useful guidance in pavement structure design against rutting. However, temperature, as one key factor influencing the shakedown limit of asphalt pavements, has barely been considered. In this paper, the shakedown phenomenon was first identified from wheel tracking tests for a pavement structure consisting of a dense bituminous macadam layer and a granular layer at 40°C. Based on a previously developed shakedown approach and the material elastic and plastic properties obtained through a series of tests, lower-bound shakedown limits of the layered system were determined and compared with the wheel tracking test results. Following that, an empirical relation between temperature and cohesion of asphalt mixture was suggested. A temperature-dependent shakedown approach was then proposed which can quickly obtain the shakedown limits of asphalt pavements over a range of temperatures. Results show that the shakedown limits decrease markedly with increasing temperature, accompanied by a shift of the failure mode from a granular layer failure to an asphaltic layer failure. One effective and economic way to enhance the pavement performance under high temperature is improving shear strength properties of asphalt mixtures. By using this method, pavement stability against rutting can be evaluated efficiently at any temperature.

Adopting a holistic three-step literature review workflow, a total of 1,639 journal articles were used in this study as the literature sample related to recycled aggregate (RA). This study summarized the existing research topics focusing on RA, gaps of current research, suggestions for promoting RA usage, and research directions for future work. A research framework was also proposed linking the existing research themes into trends in RA research. This review work serves as a foundation work to bridge the gap between scientific research and industry practice, as well as to guide the directions in RA-related academic work using an interdisciplinary approach.

In this paper, a typical stress path experienced by subsoil in a railway foundation is used in a dynamic hollow cylinder apparatus (HCA) to obtain cyclic responses of soils subjected to moving trainloads. This is achieved through varying axial force, torque, inner and outer confining pressures independently during each load cycle. A multistage test using the specific stress path is conducted on Leighton Buzzard sand considering various magnitudes of the trainloads. Comparative studies using constant confining pressures are also carried out. It is found that in both cases with constant or variable confining pressures, the long-term deformation mechanism of the sand tends to change from shakedown to incremental collapse as the load level is increased. It was noticed that the increase rates of vertical permanent strain of the two cases are close if they have similar maximum ratios of deviator stress to mean effective stress (q/p)max and ratios of peak deviator stress to average mean effective stress qmax/pavg.

Purpose The purpose of this paper is to present a pedagogical practice in the project-based assessment of architectural, engineering and construction (AEC) students’ interdisciplinary building design work adopting BIM. This pedagogical practice emphasizes the impacts of BIM, as the digital collaboration platform, on the cross-disciplinary teamwork design through information sharing. This study also focuses on collecting students’ perceptions of building information modeling (BIM) effects in integrated project design. Challenges in BIM adoption from AEC students’ perspective were identified and discussed, and could spark further research needs. Design/methodology/approach Based on a thorough review of previous pedagogical practices of applying BIM in multiple AEC disciplines, this study adopted a case study of the Solar Decathlon (SD) residential building design as the group project for AEC students to deliver the design work and construction planning. In total 13 different teams within the University of Nottingham Ningbo China, each group consisting of final year undergraduate students with backgrounds in architecture, civil engineering, and architectural environmental engineering, worked to deliver the detailed design of the solar-powered residential house meeting pre-specified project objectives in terms of architectural esthetics, structural integrity, energy efficiency, prefabrication construction techniques and other issues such as budget and scheduling. Each team presented the cross-disciplinary design plan with cost estimate and construction scheduling together within group reports. This pedagogical study collected students’ reflective thinking on how BIM affected their design work, and compared their feedback on BIM to that from AEC industry professionals in previous studies. Findings The case study of the SD building project showed the capacity of BIM in enabling interdisciplinary collaboration through information exchange and in enhancing communication across different AEC fields. More sustainable design options were considered in the early architectural design stages through the cross-disciplinary cooperation between architecture and building services engineering. BIM motivated AEC student teams to have a more comprehensive design and construction plan by considering multiple criteria including energy efficiency, budget, and construction activities. Students’ reflections indicated both positive effects of BIM (e.g. facilitating information sharing) as well as challenges for further BIM implementation, for example, such as some architecture students’ resistance to BIM, and the lack of existing family types in the BIM library, etc. Research limitations/implications Some limitations of the current BIM pedagogy were identified through the student group work. For example, students revealed the problem of interoperability between BIM (i.e. Autodesk Revit) and building energy simulation tools. To further integrate the university education and AEC industry practice, future BIM pedagogical work could recruit professionals and project stakeholders in the adopted case studies, for the purpose of providing professional advice on improving the constructability of the BIM-based design from student work. Practical implications To further integrate the university education and AEC industry practice, future BIM pedagogical work could recruit professionals and project stakeholders in the adopted case study, for the purpose of providing professional advice in improving the constructability of the BIM-based design from student work. Originality/value This work provides insights into the information technology applied in the AEC interdisciplinary pedagogy. Students gained the experience of a project-based collaboration and were equipped with BIM capabilities for future employment within the AEC job market. The integrated design approach was embedded throughout the team project process. Overall, this BIM pedagogical practice emphasized the link between academic activities and real-world industrial practice. The pedagogical experience gained in this BIM course could be expanded to future BIM education and research in other themes such as interoperability of building information exchange among different digital tools.

Although the complex modulus is one of the most basic properties used in pavement analysis and design, its accurate measurement for existing pavement layers has always been a challenging ta...

Most glaciotectonically deformed deposits, including varved clays and glacial tills, are characterised by cracks and fissures. This paper presents a method for describing the yield criteria for glacitectonically deformed cohesive deposits using a model of cracked geomaterial with isotropic or anisotropic matrix. The general representation of the limit conditions for anisotropic materials in plane-strain is used to determine the yield criterion. The yield criterion represents a convex, piece-wise surface in the three-dimensional stress space revealing explicitly global, plastic properties of the materials considered. An example of using proposed yield criteria to solve a bearing capacity problem of a strip foundation constructed on a glaciotectonically cracked layer is presented. The lower and upper-bound estimates of limit loads on the strip footing are given. The limit state analysis presented in this paper can be used to solve many other geotechnical engineering problems, for example, the stability of slopes and reinforced walls or the bearing capacity of pile foundations.

This research focused on investigating the effects of recycled aggregates on the material properties of concrete and the structural performance of reinforced concrete beams. Two different sources of recycled aggregates, crushed red bricks and demolished concrete, collected from local construction and demolition wastes, were analysed. The pre-wetting method was applied to recycled coarse aggregates aiming to study its effects on concrete specimens. Experimental results assisted by regression analysis revealed that the pre-wetting method could minimize the negative effects caused by recycled aggregate itself on the concrete slump and compressive strength test results. Pre-wetting method was also found improving the dynamic modulus of elasticity for concrete specimens. Adding supplementary cementitious materials was not as effective as the pre-wetting method in enhancing concrete slump, ultrasonic pulse velocity (UPV), strength, or dynamic modulus of elasticity. The reduction of concrete UPV and compressive strength caused by recycled aggregates were more significant in the early curing age. Flexural tests on reinforced concrete beams indicated that although adding recycled concrete aggregates did not significantly change the beam failure load, the ultimate deformation of reinforced concrete beams was reduced by displaying more brittle failure behaviour. It was indicated that the failure mode of beam was changed from flexural to shear, inferring that shear capacity of beam with RCA was reduced. Future research directions were proposed focusing on the durability studies of concrete members containing recycled aggregates especially when the pre-wetting method was applied.

Lime stabilisation of organic clay has often been studied in the past. However, there is some evidence in the literature that the presence of high concentrations of organic matter in clay soil can lessen the chemical reaction between lime and clay minerals and can have detrimental effects on the engineering properties of soil. Hence, in this paper, the stress–strain behaviour and strength properties of organic soil treated with lime and sodium chloride (NaCl) are analysed. A soil mixture, prepared with 5% lime content and 1·5% humic acid, was stabilised with varying quantities of sodium chloride (0·5, 2·0 and 5·0%). Consolidated undrained and drained triaxial tests were carried out on specimens at curing periods of 7 and 28 d with applied confining pressures of 50 and 100 kPa. Scanning electron microscopy and X-ray diffraction analysis were used to observe the microstructural changes resulting from cementation materials. It was found that the introduction of sodium chloride improved considerably the strength properties of the lime-treated organic clay. The microstructural analysis also confirmed the presence of calcium silicate hydrate in a salt-treated organic clay, which was the main contributing factor to the enhanced engineering properties of the clay.

This study was designed to investigate the recent movement and current stage of China’s construction and demolition (C&D) waste recycling and reuse. Specifically, the research aimed to provide the big picture of recent C&D waste diversion practice in China, as well as to offer insights from Chinese field practitioners’ perceptions towards benefits, challenges, and recommendations of C&D recycling and reuse. This research was conducted based on a review of existing practice and a holistic approach by collecting feedback of professionals from multiple disciplines through a questionnaire-based survey. Totally 77 valid responses were received from 592 questionnaires sent. Both quantitative data and qualitative information implied that China was still at the early stage of recycling C&D wastes. Lack of client demands was identified as one of the main difficulties in C&D waste diversion. The study revealed that engineers and consultants had a more positive perception on promoting industrial training in C&D waste recycling, while construction management professionals held more conservative opinion on it. It was also found that gaining experience in C&D waste recycling and reuse would offer professionals more positive perception on the quality of products containing recycled contents. It was further implied that although governmental supervision had a high impact on China’s current C&D waste management practice, the economic viability should eventually dominate the C&D waste diversion.

Backcalculation is commonly used for determining stiffness moduli of pavement courses and its subgrade based on in situ deflection tests. However, the in situ test results are dependent on the frequency domain, which in turn has a significant influence on the backcalculation results. In this paper, one of the methods for normalising the frequency of load and displacement functions obtained from a dynamic impulse generated by a falling weight deflectometer (FWD) test is verified. The assessment of the method is carried out based on backcalculation results of pavement deflection tests induced by both the dynamic and static loads and an independent numerical experiment. The analysis carried out in this paper shows that the normalisation of vertical displacements and pavement loads to the values corresponding to the frequency of 0 Hz improves the accuracy of the backcalculation results. It can be concluded that the frequency normalisation procedure is an effective way for standardising the boundary conditions in the backcalculation of flexible pavements.

Applying cement grout with a high compressive strength to a porous layer made of asphalt concrete results in a pavement with the properties of an intermediate type that combines the characteristics of both flexible and rigid pavements. This solution is known as Grouted Macadam (GM). Despite a wide range of test results on the GM pavements presented in the literature, there are very few advanced modelling solutions formulated in the scope of bearing capacity measured in situ be means of a Falling Weight Deflectometer. This paper turns out that the seemingly small frequency of loading (≈20 Hz) generated during pavement deflection measurements using a Falling Weight Deflectometer-like device, has a significant impact on the backcalculation results of GM pavements. The study shows that, introducing frequency normalisation of both the pavement loading and vertical displacements to the backcalculation, can limit the statistical scatter of backcalculation results by close to a half in comparison with the classical backcalculation procedure.

Many shaft collapses are related to the deterioration and failure of the masonry shaft lining materials. In modern mine shaft, concrete is widely used to provide support. To analyse shafts stability, the properties of the lining need to be well defined. The behaviour of masonry and concrete can be considerably affected by long-term exposure to harsh mine water. This paper presents a study which focuses on the weathering effects of mine water on lining materials (brick, mortar, and concrete). To reproduce the weathering process, samples were placed into solutions of potable water, artificial mine water, and a more aggressive mine-water solution for just less than one year. Four phases of laboratory tests were conducted throughout the time period to assess the degradation of mechanical properties of the lining materials. Particular attention is given to the degradation of material strength and stiffness. Results indicate that the harsh acidic mine water has pronounced detrimental effects on the strength and stiffness of mortar. The weathering process is shown to have the most significant effect on the stiffness of concrete and mortar. It is also shown that the use of mass loss as an index for evaluation of mechanical properties may not be appropriate.

The aim of this paper is to establish a correlation between the liquid limit value obtained in the Casagrande apparatus (w L/cup ) and in the cone penetrometer (w L/cone ) for typical glacial sediments from west-central Poland and compare them with the correlation equations published in the literature. The following correlation was formulated: w L/cone = 0.91w L/cup + 1.98 . The analysis presented in this paper proves that deriving a generalised and universal relationship w L/cup /w L/cone for all cohesive soils, regardless of their origin, is not possible. It is verified that in the range of low values of liquid limit cone penetrometer gives higher values of w L than those obtained from the Casagrande apparatus. However, for the Polish postglacial soils analysed in this paper, the cone penetrometer underestimates the results in relation to Casagrande apparatus above w L = 22%. For the purpose of this study, w L = 22% was defined as ‘the point of equivalent results’ (w L/cone =w L/cup ). The aim of this paper is to establish a correlation between the liquid limit value obtained in the Casagrande apparatus (w L /cup) and in the cone penetrometer (w L/cone ) for typical glacial sediments from west-central Poland and compare them with the correlation equations published in the literature. The following correlation was formulated: w L/cone = 0.91w L/cup + 1.98. The analysis presented in this paper proves that deriving a generalized and universal relationship w L/cup /w L/cone for all cohesive soils, regardless of their origin, is very challenging and may not be reliable for use in the engineering practice. It is verified that, in the range of low values of liquid limit, the cone penetrometer gives higher values of w L than those obtained from the Casagrande apparatus. However, for the Polish postglacial soils analysed in this paper, the cone penetrometer underestimates the results in relation to the Casagrande apparatus above w L = 22%. For the purpose of this study, w L = 22% was defined as “the point of equivalent results” (w L/cone = w L/cup ).

A comprehensive experimental study on the strain softening and instability behaviour of granular soil under plane-strain conditions is presented in this thesis. A new plane-strain apparatus was developed and used in this study. The study was carried out by conducting specialised plane-strain tests on a marine dredged sand. Based on several series of drained and undrained tests, the drained and undrained characteristics of the sand under plane-strain conditions were determined. It was shown that the critical state line under the plane-strain condition is different from that under the triaxial condition. The strain softening behaviour of sand was investigated using strain path testing method. Two types of strain softening, material softening and banding softening were identified. Doctor of Philosophy (CEE)

This study extends the existing reviews targeting the Journal of Professional Issues in Engineering Education and Practice (JPIEEP) by incorporating the text-mining review methodology. A to...

This paper presents an experimental investigation revisiting the anisotropic behavior of geomaterials in drained monotonic shear using Hollow Cylinder Apparatus. The test program has been designed to cover the effect of material anisotropy, pre-shearing and material density on the behavior of Leighton Buzzard sand. Experiments have also been performed on glass beads to understand the effect of particle shape. The test results demonstrate that the stress-strain-strength behavior of the specimen shows strong dependence on the principal stress direction. The pre-shearing history, material density and particle shape are found to be influential. The deformation non-coaxiality, i.e., non-coincidence between the principal stress direction and the principal strain rate direction is observed. In particular, it was found that non-coaxiality is more significant in presheared specimens. This paper also explains the phenomenological observations based on the recently acquired understanding in micromechanics, with attention focused on strength and deformation non-coaxiality.

BIM has been undergoing continuous growth in the global architecture, engineering, and construction (AEC) industry. However, knowledge development within BIM management is lagging behind its implementation. This study initiates a BIM management–based framework involving BIM climate, which is measured by individual BIM practitioners’ perceptions. Subgroup comparison is highlighted in measuring perceptions. Regional variance in BIM climate is addressed in applying the framework by adopting an empirical case study within the context of China’s AEC industry. The case study uses Shanghai and Wenzhou, which represent a BIM-leading metropolitan city and a BIM-developing counterpart, respectively, for the comparative analysis of BIM climate. Based on data collected from a questionnaire survey sent to BIM practitioners from these two cities, it is revealed that Shanghai, as the BIM-leading city in China, has somewhat significant differences in BIM climate compared with Wenzhou. For example, Shanghai BIM practitioners perceive fewer challenges in BIM training, but higher risk in adopting BIM technology. This study contributes to both academic work and practice in BIM based on its initiation of the concept of BIM climate and the case study of BIM-climate comparison. Academically, this holistic study proposes the BIM management– related knowledge framework aiming to fill the knowledge gap in BIM climate and culture, and it could be further applied in subclimates and subcultures within BIM. Practically, the case study provides insights to stakeholders regarding regional variations in BIM climate when promoting BIM practice or establishing BIM guidelines.

As an alternative to the traditional structural analysis adopting computer-aided modeling and evaluation, this pedagogical research provides an integrated teaching and learning approach by mapping cognitive domains in a newly launched course, Woodwork Fabrication and Analysis, for second-year students. The course incorporates ancient Chinese woodworking tradition into the integrated learning activities involving engineering graphics, mechanics of materials, hands-on fabrication, and structural modeling/analysis. Comparing the traditional and new courses in terms of their effectiveness in enhancing student learning of structural engineering subjects, both courses are designed to achieve consistent learning outcomes (e.g., to develop structural analysis skills). This study demonstrates student work in engineering drawing and structural analysis reflecting their critical thinking and active learning in the new course. Students from both the traditional and new courses were surveyed about their overall satisfaction with their selected course, their perceptions of the course effectiveness in enhancing civil engineering–related skills, and their expectations of the effect of the course on their further study and work. With the student sample from the traditional course as the control group, the comparative study reveals that the integrated teaching and learning approach in the new course could lead to higher overall student satisfaction and more-positive perceptions of the course effectiveness in enhancing structural analysis–related skills. This pedagogical study will serve as a reference for other civil engineering educators in adopting integrated teaching and learning in lower-year undergraduate education.

Surface subsidence is a concern for many underground mining activities. If not predicted, this phenomenon can cause severe infrastructure damage. In this paper, a computer model is used to predict surface subsidence after the controlled collapse of a coal mine at Naburn in North Yorkshire, England. Scarcity of data on the characteristics of deep underground distressed and caved zones around coal mining excavations makes the numerical prediction of mining-induced subsidence very difficult. The authors derive appropriate input parameters for the numerical model using available borehole data with all necessary justifications provided. Simulations are performed using the commercial software FLAC3D. Different constitutive models, such as Mohr-Coulomb, modified Hoek-Brown, strain-softening, double-yield, and modified Cam-clay are used to obtain surface subsidence profiles, which are compared against measurements taken at the site. Special attention is given to numerically simulating processes involved in the underground movements. It is shown that none of the models listed above can reasonably predict the surface subsidence profile.

This paper presents an experimental investigation revisiting the anisotropic stress–strain–strength behaviour of geomaterials in drained monotonic shear using hollow cylinder apparatus. The test programme has been designed to cover the effect of material anisotropy, preshearing, material density and intermediate principal stress on the behaviour of Leighton Buzzard sand. Experiments have also been performed on glass beads to understand the effect of particle shape. This paper explains phenomenological observations based on recently acquired understanding in micromechanics, with attention focused on strength anisotropy and deformation non-coaxiality, i.e. non-coincidence between the principal stress direction and the principal strain rate direction. The test results demonstrate that the effects of initial anisotropy produced during sample preparation are significant. The stress–strain–strength behaviour of the specimen shows strong dependence on the principal stress direction. Preloading history, material density and particle shape are also found to be influential. In particular, it was found that non-coaxiality is more significant in presheared specimens. The observations on the strength anisotropy and deformation non-coaxiality were explained based on the stress–force–fabric relationship. It was observed that intermediate principal stress parameter b(b = (σ2 − σ3)/(σ1 − σ3)) has a significant effect on the non-coaxiality of sand. The lower the b-value, the higher the degree of non-coaxiality is induced. Visual inspection of shear band formed at the end of HCA testing has also been presented. The inclinations of the shear bands at different loading directions can be predicted well by taking account of the relative direction of the mobilized planes to the bedding plane.

Global coal mining activity is increasing due to demands for cheap energy and the availability of large coal deposits around the world; however, the risks associated with conventional coal mining activities remain relatively high. Underground coal gasification (UCG), also known as in-situ coal gasification (ISCG) is a promising alternative method of accessing energy resources derived from coal. UCG is a physical-chemical-geotechnical method of coal mining that has several advantages over traditional mining, for example, its applicability in areas where conventional mining methods are not suitable and the reduction of hazards associated with working underground. The main disadvantages of UCG are the possibility of underground water pollution and surface subsidence. This work is focused on the latter issue. A thorough understanding of subsidence issues is a crucial step to implement UCG on a wide scale. Scientists point out the scarce available data on strata deformations resulting from UCG. The former Soviet Union countries have a long history of developing the science related to UCG and experimenting with its application. However, the Soviet development occurred in relative isolation and this makes a modern review of the Soviet experience valuable. There are some literature sources dealing with Soviet UCG projects; however, they are neither up-to-date nor focus on aspects that are of particular importance to surface subsidence, including geological profiles, strata physical-mechanical properties, thermal properties of geomaterials, and temperature spreading. The goal of this work is to increase the knowledge on these aspects in the English-speaking science community.

Rotational shear is the type of loading path where samples are subjected to cyclic rotation of principal stress directions while the magnitudes of principal stresses are maintained constant. This paper presents results from an experimental investigation on the drained deformation behaviour of saturated sand in rotational shear conducted in a hollow cylinder apparatus. Two types of granular materials, Leighton Buzzard sand and glass beads are tested. A range of influential factors are investigated including the material density, the deviatoric stress level, and the intermediate principal stress. It is observed that the volumetric strain during rotational shear is mainly contractive and most of strains are generated during the first 20 cycles. The mechanical behaviour of sand under rotational shear is generally non-coaxial, i.e., there is no coincidence between the principal axes of stress and incremental strain, and the variation of the non-coaxiality shows a periodic trend during the tests. The stress rat...

Experimental results are presented in this paper to show that a runaway type of pre-failure instability can occur for sand under dilatancy rate controlled conditions when an appropriate strain increment ratio, dev/de1, is imposed. This type of instability is similar to the runaway type of instability observed for very loose sand under undrained conditions. Whether a soil element will undergo pre-failure instability depends on the difference between the strain increment ratio of the soil obtained from drained test, under a specified effective confining pressure, (dev/de1)s, and the strain increment ratio imposed during the test, (dev/de1)i, rather than the absolute magnitude of (dev/de1)i. Based on the experimental data obtained in this study it was found that an instability line can be determined from a series of strain path tests conducted at different effective confining pressures but with the same dev/de1 by joining the peak points of the effective stress paths to the origin in the q–p′ stress space. This line is similar to the instability line obtained from undrained tests on loose sand. The instability tests under dilatancy rate controlled conditions indicate that the stress ratio at the onset of instability obtained in the instability tests coincide with the peak stress ratio line. This suggests that the peak stress line can be used to predict the onset of instability under dilatancy rate controlled conditions in the same way as the use of instability line to predict the onset of instability under undrained conditions.

Building information modeling (BIM), the emerging digital technology, is undergoing increasing application in developing countries including China. Both the governmental policy and industry motivation have indicated that BIM is becoming the mainstream innovation in China’s construction industry. Nevertheless, one major concern lies in the uncertainty of BIM investment for architecture, engineering, and construction (AEC) firms. Specifically, AEC firms should have the knowledge of areas BIM investment could focus on (such as BIM software); the expected returns from BIM investment; methods to enhance the returns from BIM usage; and the risks in implementing BIM. This study adopted a questionnaire survey–based approach to address these concerns related to BIM application and risk in China. BIM practitioners from multiple AEC fields and different experience levels were recruited as the survey sample. It was found from the questionnaire survey that both internal and external collaborations should be the BIM investment priority, together with the interoperability among multiple BIM software tools. Improved multiparty communication and understanding was the highest recognized return from BIM investment. Survey participants had a high expectation of BIM application in green building projects. Subgroup analysis conveyed the information that gaining BIM practical experience would provide professionals with more confidence on returns from BIM adoption in enhancing communication and understanding. Compared to survey participants from other professions, architects tended to have more conservative views on BIM’s effect on marketing their work, project planning, and recruiting/retaining employees. The findings from this empirical study provide an overview of BIM investment, return, and implementation-related risks for AEC professionals at different stages or levels of BIM practice, as well as suggestions for relevant public authorities when developing BIM guidelines (e.g., BIM applications in prefabrication construction). As an extension of existing BIM implementation studies in developed countries, this study provides insights of BIM practical experience and associated risks in China by adopting a holistic approach and summarizing the perceptions from AEC professionals across disciplines and experience levels. The knowledge gained from this study could be further applied in other developing countries where the application of information technology is growing in AEC projects.

The global movement of building information modeling (BIM) is spreading the implementation of BIM from developed countries to other developing countries. Practitioners’ perceptions of BIM implementation in these developing countries, such as China, a giant building market that is increasing the application of BIM in the industry, have not been thoroughly understood. This research used the questionnaire method to survey 94 randomly recruited Chinese BIM professionals to investigate BIM practice and its related perceptions. Reductions in design errors and resultant construction rework were considered the top benefits of using BIM. The most important factor in achieving BIM value was noted as interoperability among various BIM tools. A comprehensive evaluation of BIM at the company level was considered a major difficulty of implementing BIM. The owner was considered the party that received the most benefits from BIM. Subgroup differences based on two major categories (i.e., participants’ profession and BIM proficiency level) were analyzed in the survey sections related to BIM implementation. Statistical analysis revealed that, generally, neither the profession nor BIM proficiency level affected participants’ perceptions of the benefits, factors, challenges, or benefited parties in BIM implementation.

The impact of high temperatures on rocks is a topic of growing importance in geotechnical engineering due to its relevance to applications such as underground nuclear fuel storage, geothermal energy resource exploration and underground coal gasification. This paper presents results from tests performed on samples of sandstone treated to a range of temperatures between 20 and 1000°C. Sandstone samples obtained from underground coal gasification trial sites in Poland were selected for the tests. Multistage triaxial tests were used to determine the mechanical properties of the samples. X-ray diffraction and thermal analyses were performed to investigate the changes in physical and chemical properties of the samples under increasing temperature. Micro-computed tomography analyses were carried out on selected samples in order to show the microstructural changes that take place as a result of the heating process. Three-dimensional characterisation of sample porosity and pore-size distribution was performed to obtain a quantitative comparison between samples subjected to different temperature treatments. The relationship between microstructure and macro-mechanical characteristics of sandstone at high temperatures is discussed. The results illustrate that the mechanical properties of sandstone are closely related to alterations of microstructure that result from increased temperatures.

The discrete element method has been used to investigate the micro mechanics of cemented sand. High pressure drained triaxial tests are modelled in 3D using a flexible membrane which allows the correct deformation to develop. Simulations with up to 12 MPa confining pressure are presented, which are compared with laboratory experiments on a sand with a range of cement contents. Cementation is modelled using ‘parallel bonds’, and various parameters and strength distributions are investigated. Varying levels of cementation are successfully modelled, with the correct qualitative behaviour observed, and the separate effects of cementation and confining pressures demonstrated. The triaxial behaviour is found to be highly influenced by the distribution of bond strengths.

Tunnelling-induced ground surface settlement prediction still adopts empirical and analytical approaches; thus a step further in using a practical numerical analysis is now a challenging task. Because the deformation during tunnelling is a three-dimensional problem, several features were incorporated in two-dimensional analyses to capture aspects that are important in governing behaviour in the missing third dimension. This paper aims to present simplified methods for ground settlement computation of tunnelling works using the PLAXIS finite-element programme. Three simplified methods – contraction ratio, stress reduction and modified grout pressure – were considered in this study. Practical application requires correlations among these three methods. Such correlations among the three methods are proposed in this study and can be used in geotechnical practice. The results were based on a series of finite-element analyses of the Blue Line Bangkok Mass Rapid Transit tunnels. The geotechnical parameters were selected based on soil investigation reports carried out for construction purposes. The soil constitutive model adopted herein was the hardening soil model on soft and stiff clays. All the finite-element simulations were compared with the measured field deformations. Therefore, the analysis results can be considered as a Class-C prediction (back-analysis).

Refereed/Peer-reviewed

This research is focused on the dynamic behavior and failure mechanisms of an ecologically vegetated bituminous mixture applied in a riverbank revetment model. The dynamic bearing capacity of the vegetated riparian slope was evaluated. The dynamic soil pressure distribution and deformation were analyzed, followed by 3D elastic&ndash, plastic finite element modeling. Experimental results showed that the cumulative vertical settlement increased rapidly with the loading time. Vegetation added into bituminous mixtures was found to be effective in inhibiting the development of the vertical displacement of sand. The research described in this paper provides a theoretical basis and guidelines for the protection of riverbank slopes.

The Bangkok metropolitan area, located on a thick river soft clay deposit, has recently started a construction project on a mass rapid transit underground railway (MRT). This paper presents a finite element study on the Bangkok MRT underground construction project. The excavation of Sukhumvit Station was selected as the case study for the FEM numerical modelling in this paper. The numerical study focuses on the initial input on the ground conditions and the constitutive soil models. The geotechnical parameters were selected based on the soil investigation reports carried out for the purpose of the construction. The parameters selected for the constitutive models used in the FEM analysis were calibrated against the laboratory testing results. Finally, all the FEM simulations were compared with the data from field investigations.

In this paper, the results of three series of drained tests carried out on sands using hollow cylinder apparatus are presented. The noncoaxiality, defined as the difference between the major principal stress direction and the corresponding principal strain increment direction, is investigated. In the first series of tests, the sand was isotropically consolidated before being sheared with the fixed principal stress direction. In the other two series of tests, the sand specimens were isotropically consolidated and then sheared by rotating the major principal stress axes while the deviator stress level was either fixed (pure stress rotation) or increased continuously (combined shear loading). The experimental results provide clear evidence for material noncoaxiality when the rotation of principal stress direction is involved. The results from these series of tests show that the degree of noncoaxiality depends on the level of deviatoric stress and the stress increment direction. It tends to decrease w...

Construction of the extension project of the Bangkok MRT Blue Line underground railway was recently started in 2011. The construction of approximately 5 km long underground tunnel and 4 deep excavations of underground station are considered to be the most important geotechnical works. The pressuremeter was selected as a high-quality in situ testing of the soil to evaluate design parameters for the project. In addition, other field and laboratory tests such as vane shear and CK0U triaxial tests were included in the investigation programme. This paper aims to present the ground conditions encountered along the MRT Blue Line extension project as well as the site investigation and interpretation techniques with particular focus on the pressuremeter tests. The results are also compared with the pressuremeter investigation from the previous Bangkok MRT project.

Existing lower-bound shakedown solutions for pavement problems are generally obtained by assuming that materials obey an associated flow rule, whereas plasticity of real materials is more inclined to a non-associated flow. In this paper, a numerical step-by-step approach is developed to estimate shakedown limits of pavements with Mohr–Coulomb materials. In particular, influences of a non-associated flow rule on the shakedown limits are examined by varying material dilation angle in the numerical calculations. It is found that the decrease of dilation angle will lead to accelerated reduction of pavement shakedown limits, and the reduction is most significant when the material friction angle is high. Furthermore, existing lower-bound shakedown solutions for pavements are extended, in an approximate manner, to account for the change of material dilation angle and the shakedown results obtained in this way agree well with those obtained through the numerical step-by-step approach. An example of pavement design using shakedown theory is also presented.

Stress history is recognised to play a major role in determining stress–strain behaviour of soil in undrained shearing. Most experimental studies on the effects of stress history on undrained behaviour are mainly limited to clean sand. In this paper, an experimental study carried out to investigate the effect of stress history on the undrained behaviour of loose sand with a small amount of fines is presented. Four series of triaxial compression tests, with different types of drained stress histories to near-failure prior to commencement of undrained shearing, were conducted. The experimental results indicate that drained pre-shearing to near-failure affects significantly the undrained behaviour of loose sand. In general, the drained pre-shearing improves the subsequent undrained behaviour of loose sand to the extent that liquefaction may not occur. It is shown that the effect of drained pre-shearing cannot be explained by the reduction in void ratio induced by drained pre-shearing. However, for specimens subjected to drained pre-shearing, $$ p_{{{\text{d}}0}}^{\prime } $$ / $$ p_{{{\text{u}}0}}^{\prime } $$ can be used as a parameter for analysing the effects of preloading history. It is also shown that for different preloading histories that brought the same change in void ratio or state parameter, drained pre-shearing to near-failure is the most effective, whereas pre-compression alone is the least effective in improving subsequent undrained behaviour of loose sand.

In this paper, drained behaviour of cemented sand under high pressure is studied. A recently developed high pressure triaxial apparatus is used. The test results indicate the significance of degree of cementation and confining pressure on the isotropic compression, volumetric change, stress-strain behaviour and stress-dilatancy relationship of cemented sand at high confining pressures. The results suggest that the influence of cementation is greater at low confining stresses and it reduces with increasing confining stress where the effect of the confining pressure becomes dominant. A Scanning Electron Microscope analysis has also been included in the paper. It revealed that the particle and cement bonding breakage at high pressure is dependent on the stress level and the cement content. The higher the confining pressure the more significant particle and cement bonding breakage is observed. The higher the cement content the fewer sand particles and cement bonds are broken.

A type of prefailure instability which occurs under fully drained conditions is studied in this paper. It is observed experimentally that when a specimen is sheared along a drained stress path involving a decrease in effective mean stress, it becomes unstable after the stress path crosses an instability line. The instability occurring under drained conditions is different from the type observed under undrained conditions. The differences and similarities between the two types of instability are elaborated. The practical implication of the study in analyzing the failure mechanisms of granular soil slope is also discussed.

Experimental data are presented in this paper to study the instability behavior of sand in strain path testing under plane-strain conditions. K0 consolidated strain path tests were conducted on Changi sand using a plane-strain apparatus. The test results show that the occurrence of pre-failure instability under plane-strain conditions is affected by the void ratio and the strain increment ratio. This is consistent with previous findings established under axisymmetric conditions. However, instability behavior of medium dense sand in strain path-controlled plane-strain tests can also be affected by shear band formation. In this case, on-failure instability takes place and failure is likely caused by shear band development. This observation is different from that in triaxial strain path-controlled tests where shear bands do not normally occur.

Flowslide is a common type of failure of granular soil slopes. Although many flowslides can be explained using static liquefaction or instability behaviour of sand under undrained conditions, some of the failures might have occurred under essentially drained conditions. In this paper, some flowslide case histories are reviewed. Typical flowslides and the possible failure mechanisms behind each flowslide are identified. Based on the laboratory studies, two new failure mechanisms are proposed and used to offer new interpretations to some of the failure cases.

Flowslide or failure of loose granular soil slopes is often explained using liquefaction or instability data obtained from undrained triaxial tests. However, under static loading conditions, the assumption of an undrained condition is not realistic for sand, particularly clean sand. Case studies have indicated that instability of granular soil can occur under essentially drained conditions (e.g., the Wachusett Dam failure in 1907). Laboratory studies on Changi sand by Chu et al. in 2003 have shown that sand can become unstable under completely drained conditions. However, these studies were carried out under axisymmetric conditions and thus, cannot be applied directly to the analysis of slope failures. In this paper, experimental data obtained from plane-strain tests are presented to study the instability behaviour of loose and dense sand under plane-strain conditions. Based on these test data, the conditions for the occurrence of drained instability in plane strain are established. Using the modified state parameter, the conditions for instability under both axisymmetric and plane-strain conditions can be unified. A framework for interpreting the instability conditions of sandy slopes developed under axisymmetric conditions also extends into plane-strain conditions.

An experimental study was carried out to investigate the static liquefaction behaviour of sand with a small amount of plastic and nonplastic fines. Five series of tests were conducted in drained and undrained conditions. The drained test results indicate not only that the failure line coincides with the critical state, but also that the development of volumetric strain during shearing was not sensitive to the initial confining pressure. In both isotropically and anisotropically consolidated undrained tests, a so-called “reverse behaviour” was consistently observed. The results were also interpreted in the critical state framework. The critical and steady state (CS/SS) data were found to trace along the same curve in e–log( p′) space, irrespective of the stress history and effective stress paths. A comparison between the isotropic consolidation line (ICL) and critical state (CS) curve showed that a small amount of fines can significantly change the shape and position of the ICL relative to the CS curve. Furthermore, the soil behaviour manifested in both drained and undrained shearing led to the development of a modified state parameter.

Experimental data to study the effect of loading mode on the strain softening and instability behavior of sand under plane-strain conditions are presented in this paper. A new plane-strain apparatus was adopted to conduct K0 consolidated drained and undrained tests under both deformation-controlled and load-controlled loading modes. The drained behavior of very loose and medium dense sand and the undrained behavior of very loose sand under plane-strain conditions were characterized. The test results show that the loading mode affects the postpeak behavior and controls whether strain softening or instability will occur in the postpeak region. Shear bands occurred in tests conducted on medium dense sand, but not in tests for very loose sand. The failure line and critical state line are not affected by the loading mode. The study also shows that the concept of a unique “ultimate state” for both dense and loose sand as previously established based on conventional drained triaxial tests is not supported by the...

Experimental data are presented in this paper to study the strain-softening behaviour of sand under plane-strain conditions. K0 consolidated strain path tests were conducted using a new plane-strain apparatus. The stress–strain behaviour of medium dense sand under plane-strain conditions was characterized. The test results show that the occurrence of pre-failure strain softening under plane-strain conditions is affected by the void ratio, the strain increment ratio and the initial effective confining stress. This is consistent with previous findings established under axisymmetric conditions. However, a pre-failure strain-softening behaviour in plane-strain tests conducted under high-confining stresses may consist of three stages, namely, material softening, banding softening, and ultimate state. This observation is different from that in triaxial tests where banding softening does not normally occur.

When a loose sand specimen is loaded under an undrained condition, it may become unstable. The instability conditions may be specified by an instability line determined using undrained tests. However, the instability behavior of sand has seldom been studied under plane-strain conditions. Experimental data obtained under both triaxial and plane-strain conditions are presented in this paper to define the instability conditions of loose sand under plane-strain conditions. Using the state parameter, a unified relationship can be established between the normalized slope of instability line and the state parameters for both axisymmetric and plane-strain conditions. Using this relationship, the instability conditions established under axisymmetric conditions can also be used for plane-strain conditions.