3D ground model development for an active landslide in Lias mudrocks using geophysical, remote sensing and geotechnical methods

A ground model of an active and complex landslide system in instability prone Lias mudrocks of North Yorkshire, UK is developed through an integrated approach, utilising geophysical, geotechnical and remote sensing investigative methods. Surface geomorphology is mapped and interpreted using immersive 3D visualisation software to interpret airborne light detection and ranging data and aerial photographs. Subsurface structure is determined by core logging and 3D electrical resistivity tomography (ERT), which is deployed at two scales of resolution to provide a means of volumetrically characterising the subsurface expression of both site scale (tens of metres) geological structure, and finer (metre to sub-metre) scale earth-flow related structures. Petrophysical analysis of the borehole core samples is used to develop relationships between the electrical and physical formation properties, to aid calibration and interpretation of 3D ERT images. Results of the landslide investigation reveal that an integrated approach centred on volumetric geophysical imaging successfully achieves a detailed understanding of structure and lithology of a complex landslide system, which cannot be achieved through the use of remotely sensed data or discrete intrusive sampling alone

Moisture monitoring in clay embankments using electrical resistivity tomography

Systems and methods are described for monitoring temporal and spatial moisture content changes in clay embankments using electrical resistivity tomography (ERT) imaging. The methodology is based upon development of a robust relationship between fill resistivity and moisture content and its use in the transformation of resistivity image differences in terms of relative moisture content changes. Moisture level and moisture content movement applications are exemplified using two case histories from the UK. The first is the BIONICS embankment, near Newcastle (NE England), which was constructed in 2005 using varying degrees of compaction of a medium plasticity sandy, silty clay derived from the Durham Till. The second is a Victorian embankment south of Nottingham (Central England), constructed in 1897 using end tipping of Late Triassic siltstone and mudstone taken from local cuttings. Climate change forecasts for the UK suggest that transportation earthworks will be subjected to more sustained, higher temperatures and increased intensity of rainfall. Within the context of preventative geotechnical asset maintenance, ERT imaging can provide a monitoring framework to manage moisture movement and identify failure trigger conditions within embankments, thus supporting on demand inspection scheduling and low cost early interventions

Primary health care for Aboriginal Australian women in remote communities after a pregnancy with hyperglycaemia

Background: Hyperglycaemia in pregnancy contributes to adverse outcomes for women and their children. The postpartum period is an opportune time to support women to reduce cardiometabolic and diabetes risk in subsequent pregnancies. Aims: To identify strengths and gaps in current care for Aboriginal women after a pregnancy complicated by hyperglycaemia. Methods: A retrospective review of the 12 month postpartum care provided by primary health centres in remote Australia in 2013-2014 identified 195 women who experienced hyperglycaemia in pregnancy (gestational diabetes (GDM) (n = 147), type 2 diabetes (T2D) (n = 39), and unclear diabetes status (n = 9)). RESULTS: Only 80 women (54%) with GDM had postpartum glycaemic checks. Of these, 32 women were diagnosed with prediabetes (n = 24) or diabetes (n = 8). Compared to women with GDM, women with T2D were more likely to have their weight measured (75% vs. 52%, p <0.01), and smoking status documented as "discussed" (65% vs. 34%, p < 0.01). Most women (97%) accessed the health centre at least once in the 12 month postpartum period but, during these visits, only 52% of women had service provision, either structured or opportunistic, related to diabetes. Conclusion: High rates of dysglycaemia among women screened for T2D after GDM in the 12 month postpartum period highlight the need for increased screening and early intervention to prevent the development of T2D and its complications. Whilst a clear strength was high postpartum attendance, many women did not attend health services for diabetes screening or management.Anna Wood, Diana MacKay, Dana Fitzsimmons, Ruth Derkenne, Renae Kirkham, Jacqueline A. Boyle, Christine Connors, Cherie Whitbread, Alison Welsh, Alex Brown, Jonathan E. Shaw, and Louise Maple-Brow

Crossover exponent in O(N) phi^4 theory at O(1/N^2)

The critical exponent phi_c, derived from the anomalous dimension of the bilinear operator responsible for crossover behaviour in O(N) phi^4 theory, is calculated at O(1/N^2) in a large N expansion in arbitrary space-time dimension d = 4 - 2 epsilon. Its epsilon expansion agrees with the known O(epsilon^4) perturbative expansion and new information on the structure of the five loop exponent is provided. Estimates of phi_c and the related crossover exponents beta_c and gamma_c, using Pade-Borel resummation, are provided for a range of N in three dimensions.Comment: 8 latex page

Estimation of electrode positions from sparsely distributed reference points for long term geoelectric monitoring of an active landslide (abstract only)

Recent improvements in the capabilities of electrical resistivity tomography (ERT) in ground imaging have resulted in an increased application of this technique to the characterisation of landslides. Time-lapse ERT offers the possibility to image changes in the resistivity distribution over time, which may indicate hydrological processes triggering landslide movement. However, these measurements depend on knowing the exact locations of the electrodes, which, especially on landslides, are changing over time

4D electrical resistivity tomography monitoring of soil moisture dynamics in an operational railway embankment

The internal moisture dynamics of an aged (> 100 years old) railway earthwork embankment, which is still in use, are investigated using 2D and 3D resistivity monitoring. A methodology was employed that included automated 3D ERT data capture and telemetric transfer with on-site power generation, the correction of resistivity models for seasonal temperature changes and the translation of subsurface resistivity distributions into moisture content based on petrophysical relationships developed for the embankment material. Visualization of the data as 2D sections, 3D tomograms and time series plots for different zones of the embankment enabled the development of seasonal wetting fronts within the embankment to be monitored at a high-spatial resolution and the respective distributions of moisture in the flanks, crest and toes of the embankment to be assessed. Although the embankment considered here is at no immediate risk of failure, the approach developed for this study is equally applicable to other more high-risk earthworks and natural slopes

Deterioration model and condition monitoring of aged railway embankment using non-invasive geophysics

Effective management of railway infrastructure is becoming increasingly reliant upon remote condition monitoring of geotechnical asset condition. Current monitoring approaches focus on confirmation of the morphological effects caused by subsurface processes driving deterioration. However, geophysical imaging offers new opportunities for ‘predict and prevent’ practices, providing access to monitoring internal property change patterns preceding these morphological responses. Geophysical methods utilize disturbances that propagate through and holistically sample earthworks and are especially suited to imaging the unique heterogeneity of aged embankments. In this case study, surface wave seismic surveys are interpreted to construct a stiffness ground model consistent with a heterogeneous embankment comprising local borrow materials. Time-lapse electrical resistivity imaging was also used to investigate and visualise ground water ingress and movement within this ground model. Ground water movement was shown to be highly dynamic, responding very quickly to local storm events with infiltration into the embankment within hours. Subsequent wetting and drying cycles throughout the embankment’s lifespan have caused the dissolution, mobilisation and re-precipitation of soluble minerals within the fill materials. This process has driven the deterioration of the fill fabric, which is evidenced in thin sections by voids and localised rupture about in situ mineral growths. Finally, we provide a framework showing how geophysical methods could support more risk-based asset management practices of the future