The Leaning Tower of Pisa Revisited

Stabilisation of the Leaning Tower of Pisa was achieved by means of an innovative method of soil extraction which induced a small reduction in inclination not visible to the casual onlooker. Its implementation has required advanced computer modelling, large-scale development trials, an exceptional level of continuous monitoring and daily communication to maintain control. Recently a number of historical examples have been found of the application of soil extraction to straightening leaning buildings – the earliest being 1832. Contemporary accounts of the work bring out interesting and important similarities and serve as reminders of the inventiveness and resourcefulness of engineers long before modern soil mechanics came into being

Experimental investigations of bolted segmental grey cast iron lining behaviour

The need for the research reported in this paper was driven by the Crossrail project in London for which new tunnels were constructed close to numerous existing operational tunnels of the London Underground (LU) network. This research is based on experimental work conducted on half-scale grey cast iron (GCI) tunnel lining segments with chemical composition similar to the Victorian age GCI segments in the LU network. This paper discusses the deformation behaviour of the bolted segmental lining under the influence of factors such as overburden pressure, bolt preload and presence of grommets at small distortions. The measured behaviour of the segmental lining is compared against the calculated response of a continuous lining based on the assumption of elasticity. The industry practice for tunnel lining assessment is to calculate the induced bending moment in the tunnel lining using an elastic continuum model, while adopting a reduced lining stiffness to take into account the presence of the joints. Case studies have recorded that both loosening and tightening of lining bolts have been used as mitigation measures to reduce the impact of new tunnel excavations on existing GCI tunnels. The experimental work on the half-scale GCI lining has shown that a bolted segmental lining behaves as a continuous ring under small distortions imposed when subjected to hoop forces relevant to the depth of burial of LU tunnels. In the presence of hoop force, joint opening was minimal and the magnitude of preload in the bolts had little impact on the behaviour of the lining. It is therefore concluded that disturbance of the bolts in existing tunnels is not recommended as a mitigation measure as in addition to being ineffective it is both time consuming and introduces the risk of damaging the tunnel lining flanges

Numerical modelling of perimeter pile groups in clay

The load distribution among piles in a group varies such that the inner piles often carry a smaller share of the total load compared to the outer piles, which is a result of increased soil–pile interaction. The main objective of this paper is to establish the relative effectiveness of pile groups with no inner piles (perimeter group), when compared to the more common grid configuration. The numerical investigation utilized the finite element programme ABAQUS and considered a range of variables that affect pile group behaviour including number of piles, pile spacing, length/diameter ratio, and soil strength. It was demonstrated that a complete grid group is less efficient than a perimeter group, where efficiency is defined as the load capacity of the whole group expressed as a ratio of the number of piles in the group multiplied by the load capacity of a single isolated pile. Efficiencies close to unity were observed for some perimeter groups. Perimeter groups also showed that a “block” type group failure could occur, where piles were placed at a spacing of less than 2.0 pile diameters,d, centre-to-centre. This often, but not always, led to a reduction in the efficiency of the pile group

Managing diversity in organisations: practitioner and academic perspectives: report from a gender in management special interest group research event

Purpose - This report aims to provide a brief summary of the presentations made by researchers and practitioners at the Gender in Management Special Interest Group’s research event, Managing Diversity in Organisations: Practitioner and Academic Perspectives. Design/methodology/approach - The research seminar was chaired by Dr. Adelina Broadbridge (University of Stirling) and Dr. Gillian Maxwell (Glasgow Caledonian University), and featured five presentations related to diversity in organisations, with a focus on gender issues. Twenty-five delegates were in attendance. Findings - The academic research presented provided empirical evidence that women continue to face barriers to career progress in a number of industry sectors. The industry presentations provided examples of organisational efforts to improve diversity both among staff and customers. Research limitations/implications - More needs to be done to ensure that women enjoy career opportunities equal to those of men in a variety of industry sectors. Even in organisations where women are comparatively well represented, such as professional services firms, research indicates that they are disadvantaged in terms of career development and progress. Originality/value - This session provided a valuable opportunity for practitioners and academics to meet and share information regarding the state of diversity in today’s workplace

Preventive Training Program Feedback Complexity, Movement Control, and Performance in Youth Athletes

Context: Preventive training programs (PTPs) reduce injury risk by improving movement control. Corrective feedback is important; however, many cues at once may be too complicated for athletes. Objective: To compare movement control and long-jump (LJ) changes in youth athletes participating in a season-long PTP, with simplified feedback, traditional feedback, or a warmup of the coaches\u27 choosing. Design: Cluster-randomized controlled trial. Setting: Soccer fields. Patients or Other Participants: A total of 420 athletes (simplified feedback = 173, traditional feedback = 118, and control = 129; age = 11 ± 3 years). Intervention(s): Teams were randomized into the simplified PTP, traditional PTP, or control group. Simplified and traditional PTPs lasted 10 to 12 minutes and used the same exercises. The simplified PTP provided only sagittal-plane feedback (eg, “get low”), and the traditional PTP provided feedback targeting all motion planes (eg, “don\u27t let your knees cave inward”). Research assistants administered the PTP warmups 2 to 3 times/week for the season. Control team coaches chose and ran their own warmup strategies. Main Outcome Measure(s): Participants completed 4 sessions (preseason [PRE], postseason [POST] at approximately 8 weeks after PRE, retention 1 [R1] at 6 weeks postseason, and retention 2 [R2] at 12 weeks postseason). They performed 3 trials of a jump-landing task, which was evaluated using the Landing Error Scoring System (LESS) and 2 recorded standing LJ trials at each test session. A time series panel was used to evaluate group differences across time points for the LESS and LJ. Results: Change score analyses revealed improvements in the LESS score from PRE to POST for all groups. Improvements from PRE were retained at R1 and R2 for the intervention groups (simplified and traditional). The traditional group demonstrated better LJ performance at POST (P \u3c .001) and R1 (P = .049) than the simplified or control group. Conclusions; Simplified cues were as effective as traditional cues in improving LESS scores from PRE to POST season. Participating in PTPs, regardless of their complexity, likely provides movement benefits

What is the comparative health status and associated risk factors for the Métis? A population-based study in Manitoba, Canada

<p>Abstract</p> <p>Background</p> <p>Métis are descendants of early 17^thcentury relationships between North American Indians and Europeans. This study's objectives were: (1) to compare the health status of the Métis people to all other residents of Manitoba, Canada; and (2) to analyze factors in predicting the likelihood of diabetes and related lower limb amputation.</p> <p>Methods</p> <p>Using de-identified administrative databases plus the Métis Population Database housed at the Manitoba Centre for Health Policy, age/sex-adjusted rates of mortality and disease were calculated for Métis (n = 73,016) and all other Manitobans (n = 1,104,672). Diseases included: hypertension, arthritis, diabetes, ischemic heart disease (age 19+); osteoporosis (age 50+); acute myocardial infarction (AMI) and stroke (age 40+); total respiratory morbidity (TRM, all ages). Using logistic regression, predictors of diabetes (2004/05-2006/07) and diabetes-related lower-limb amputations (2002/03-2006/07) were analyzed.</p> <p>Results</p> <p>Disease rates were higher for Métis compared to all others: premature mortality before age 75 (4.0 vs. 3.3 per 1000, p < .001); total mortality (9.7 vs. 8.4 per 1000, p < .001); injury mortality (0.58 vs. 0.51 per 1000, p < .03); Potential Years of Life Lost (64.6 vs. 54.6 per 1000, p < .001); all-cause 5-year mortality for people with diabetes (20.8% vs. 18.6%, p < .02); hypertension (27.9% vs. 24.8%, p < .001); arthritis (24.2% vs. 19.9%, p < .001), TRM (13.6% vs. 10.6%, p < .001); diabetes (11.8% vs. 8.8%, p < .001); diabetes-related lower limb amputation (24.1 vs. 16.2 per 1000, p < .001); ischemic heart disease (12.2% vs. 8.7%, p < .001); osteoporosis (12.2% vs. 12.3%, NS), dialysis initiation (0.46% vs. 0.34%, p < .001); AMI (5.4 vs. 4.3 per 1000, p < .001); stroke (3.6 vs. 2.9 per 1000, p < .001). Controlling for geography, age, sex, income, continuity of care and comorbidities, Métis were more likely to have diabetes (aOR = 1.29, 95% CI 1.25-1.34), but not diabetes-related lower limb amputation (aOR = 1.13, 95% CI 0.90-1.40, NS). Continuity of care was associated with decreased risk of amputation both provincially (aOR = 0.71, 95% CI 0.62-0.81) and for Métis alone (aOR = 0.62, 95% CI 0.40-0.96).</p> <p>Conclusion</p> <p>Despite universal healthcare, Métis' illness and mortality rates are mostly higher. Although elevated diabetes risk persists for the Métis even after adjusting for sociodemographic, healthcare and comorbidity variables, the risk of amputation for Métis appears more related to healthcare access rather than ethnicity.</p

Characterization of the material response in the granular ratcheting

The existence of a very special ratcheting regime has recently been reported in a granular packing subjected to cyclic loading \cite{alonso04}. In this state, the system accumulates a small permanent deformation after each cycle. After a short transient regime, the value of this permanent strain accumulation becomes independent on the number of cycles. We show that a characterization of the material response in this peculiar state is possible in terms of three simple macroscopic variables. They are defined that, they can be easily measured both in the experiments and in the simulations. We have carried out a thorough investigation of the micro- and macro-mechanical factors affecting these variables, by means of Molecular Dynamics simulations of a polydisperse disk packing, as a simple model system for granular material. Biaxial test boundary conditions with a periodically cycling load were implemented. The effect on the plastic response of the confining pressure, the deviatoric stress and the number of cycles has been investigated. The stiffness of the contacts and friction has been shown to play an important role in the overall response of the system. Specially elucidating is the influence of the particular hysteretical behavior in the stress-strain space on the accumulation of permanent strain and the energy dissipation.Comment: 13 pages, 20 figures. Submitted to PR

An improved experimental test set-up to study the performance of granular columns

This paper describes an innovative design of a newly developed large test setup for testing the performance of footings supported on soft clay reinforced with granular columns. This advanced testing method is used to examine the settlement of footings supported on granular columns. Two important features of the equipment are (a) the axial loading system which allows samples to be consolidated under Ko condition while the load is applied onto a small foundation area of the sample, and (b) a relatively large sample size of 300-mm diameter and 400-mm high. The system is also equipped with pressure cells located beneath the footing and top cap to measure the pressure distribution with respect to foundation displacement and a lateral strain gage to monitor boundary effects. This paper reports on some of the early findings from the preliminary tests carried out using this equipment. Samples for testing were prepared by consolidating kaolin slurry in a large one-dimensional consolidation chamber. The granular columns were installed using the replacement method by compacting crushed basalt (uniformly graded with 90 % between 1.5–2-mm particle sizes) into a preformed hole. The preliminary tests have yielded promising results, validating the functionality of the equipment and support the prospect of increasing the knowledge with respect to settlement response and design of a footing supported on granular columns

Earth pressure on cantilever walls at design retained heights

There are many methods for the analysis and design of embedded cantilever retaining walls. They involve various different simplifications of the pressure distribution to allow calculation of the limiting equilibrium retained height and the bending moment when the retained height is less than the limiting equilibrium value, i.e. the serviceability case. Recently, a new method for determining the serviceability earth pressure and bending moment has been proposed. This method makes an assumption defining the point of zero net pressure. This assumption implies that the passive pressure is not fully mobilised immediately below the excavation level. The finite element analyses presented in this paper examine the net pressure distribution on walls in which the retained height is less, than the limiting equilibrium value. The study shows that for all practical walls, the earth pressure distributions on the front and back of the wall are at their limit values, Kp and K-a respectively, when the lumped factor of safety F-r is less than or equal to2.0. A rectilinear net pressure distribution is proposed that is intuitively logical. It produces good predictions of the complete bending moment diagram for walls in the service configuration and the proposed method gives results that have excellent agreement with centrifuge model tests. The study shows that the method for determining the serviceability bending moment suggested by Padfield and Mair(1) in the CIRIA Report 104 gives excellent predictions of the maximum bending moment in practical cantilever walls. It provides the missing data that have been needed to verify and justify the CIRIA 104 method

Twin-tunnelling-induced ground movements in clay

Modern tunnelling methods aim to reduce ground movements arising from the construction process. In clay strata the usual method of construction is by tunnel boring machine, which allows close control of the tunnelling process; however, any movements have the potential to cause damage to existing structures at, and below, the ground surface. The construction of underground rail systems often comprises two tunnels running in opposite directions. Common practice for assessing construction-generated movements around these tunnels is to make predictions based upon individual tunnel construction and utilise superposition to generate a total deformation profile. This approach does not take into account the strain- or stress-dependent effects between tunnel constructions. A delay may result in unanticipated ground movements generated by the construction of the second tunnel. The effect of this delay on the ground movements arising between the first and the second tunnel construction process was investigated in a series of plane strain centrifuge tests. The ground movements at and below the surface were monitored and were assessed against superposition-based predictions for surface settlement with the outcomes highlighting some inconsistencies. A procedure for predicting both surface and subsurface vertical settlement profiles in the plane transverse to the advancing tunnels in clay is suggested