Displacement Zone Research Articles

Ground failure and soil erosion caused by bursting of buried water pipeline: experimental and numerical investigations

Pressurized water pipelines buried in an urban environment are prone to bursting failures, threatening public safety and traffic convenience. The limited studies in literature just focused on soil fluidization while few studies considered ground failure, shear strain, soil erosion and the influence of leakage locations during pipe bursts. In this study, extensive experimental tests along with a finite difference method – discrete element method (FDM-DEM) solid–fluid coupling analysis were conducted to investigate these issues. It was disclosed that the failure development during pipe bursts can be divided into three stages, i.e., seepage diffusion, erosion cavity expansion, and soil fluidization. By digital image correlation (DIC) analysis of the experimental results, a wedge-shaped displacement zone in ground was identified, with peak shear strain near its boundaries. Moreover, it was revealed that leakage locations affected the expansion origin of erosion cavity; as the burial depths increased, the ground heave range increased linearly; the maximum water outflow distance was closely related to the internal pressures of buried pipeline, which could be modeled by a square root formula based on turbulent jet theory. Mesoscopic analyses revealed that finer particles were more susceptible to erosion during pipe bursts because of the low possibility of forming strong connections with surrounding particles. The findings yielded from this study can enhance the understanding of pipe bursts and help professionals mitigate potential damage.

Fatigue and Autofrettage Analysis of Steel Sleeve Based on Precision Fit under Ultra High Pressure

Abstract In order to ensure precision fit between steel sleeve and plunger, copper sleeve and the other parts of the ultra high pressure plunger pump, as well as increase the fatigue life of steel sleeve, this paper made the analysis of work process and fatigue life of ultra high pressure autofrettage steel sleeve of plunger pump based on both analytical method and FEM. The elastic-plastic boundary radius, radial stress and plastic zone displacement were obtained based on the elastic-plastic mechanics analysis of ultra high pressure steel sleeve. The functional relationship built related to precision fit among autofrettage pressure, inner diameter expectation and displacement could ensure the machining dimension of inner diameter of steel sleeve and realize the precise control of inner diameter of steel sleeve. The analytical method and FEM for calculating fatigue life was also proposed, which are verified by experiment. The research shows that machining dimension is determined by inner diameter expectation in the autofrettage process to ensure precision fit; autofrettage treatment can reduce the working stress level of the steel sleeve and extend the fatigue life remarkably. These conclusions contribute to guide the design of steel sleeve.

Dentoalveolar effects of open-bite correction with the dual action vertical intra-arch technique: A finite element analysis.

To evaluate tooth displacement and periodontal stress generated by the dual action vertical intra-arch technique (DAVIT) for open-bite correction using three-dimensional finite element analysis. A three-dimensional model of the maxilla was created by modeling the cortical bone, cancellous bone, periodontal ligament, and teeth from the second molar to the central incisor of a hemiarch. All orthodontic devices were designed using specific software to reproduce their morpho-dimensional characteristics, and their physical properties were determined using Young's modulus and Poisson's coefficient of each material. A linear static simulation was performed to analyze the tooth displacements (mm) and maximum stresses (Mpa) induced in the periodontal ligament by the posterior intrusion and anterior extrusion forces generated by the DAVIT. The first and second molars showed the greatest intrusion, whereas the canines and lateral incisors showed the greatest extrusion displacement. A neutral zone of displacement corresponding to the fulcrum of occlusal plane rotation was observed in the premolar region. Buccal tipping of the molars and lingual tipping of the anterior teeth occurred with intrusion and extrusion, respectively. Posterior intrusion generated compressive stress at the apex of the buccal roots and furcation of the molars, while anterior extrusion generated tensile stress at the apex and apical third of the palatal root surface of the incisors and canines. DAVIT mechanics produced a set of beneficial effects for open-bite correction, including molar intrusion, extrusion and palatal tipping of the anterior teeth, and occlusal plane rotation with posterior teeth uprighting.

Evolution of the transtensional Barreirinhas pull-apart system in the Brazilian Equatorial margin and its correlation with the African conjugate counterpart

The Barreirinhas pull-apart system encompasses marginal basins in divergent and transform margin segments in the central sector of the Brazilian Equatorial Margin and its African conjugate counterpart. This ancient pull-apart system evolved through transtensional strike-slip motion within a highly heterogeneous crystalline basement affected by multiple rift phases. The geometry and development of pull-apart structural elements during the final rifting phase before continental breakup and the mechanisms and extent to which they were influenced by preexisting crustal heterogeneities are comprehensively addressed using an extensive database of potential field (magnetic and gravity) and 2D seismic reflection data. We also assess the lithospheric thermomechanical conditions and their influence on transtensional extension throughout Curie Point Depth, Heat Flow, and Moho depth, derived from potential field data and published seismological models. Plate reconstruction of Brazilian and African equatorial margins based on gravity patterns and comparison with sandbox analog models allow a 3D synoptic model to reveal the Barreirinhas pull-apart system evolution during the Equatorial Atlantic opening. During the rift phase I, the location of major grabens was controlled by favorably oriented Neoproterozoic shear zones, while the cooler, stronger, and thicker crust beneath cratonic areas formed the western barrier to strike-slip rift activity during rift phase II. This same geological domain anchored the onset of the pull-apart system in the last rift phase III, whose principal displacement zones developed along the extensive oceanic fracture zones linked by sigmoidal fault systems. Toward the end of the rift phase, a large asymmetric lozangle to a lazy-Z-shaped, pull-apart basin developed above low overlapping ∼90°, releasing stepover in oblique transtensional strike-slip motion.

Research on coal wall failure and stability control technology of large coal seams with a soft and thick seam

AbstractTo address the issues of coal rib instability and high occurrence of roof falls in high extraction height fully mechanized coal mining of soft coal seams, this study comprehensively employs theoretical analysis, numerical calculations, and field industrial experiments. By analyzing the distribution characteristics of coal rib displacement and deformation instability zones under different mechanical parameters of soft coal seams, the instability mechanism of coal ribs in high extraction height mining of thick and soft coal seams is revealed, and corresponding stability control techniques for high extraction height coal ribs and supports are developed. The study shows that the stability of coal ribs in high extraction height mining fields of soft and thick coal seams decreases as the values of mechanical parameters decrease. In other words, the smaller the cohesion and deformation parameters of the coal body, the more prone the coal rib is to roof falls. By utilizing advanced deep‐hole static water infusion technology, the frequency of roof falls in extremely soft high extraction height working faces is reduced by 80%, the average depth of roof falls is decreased by 35%, and the average length of roof falls is reduced by 50%. The stability of the coal ribs is effectively improved.

Investigation on failure of deep excavations in erodible sandy strata triggered by heavy rainfall

To date, few researches have been contributed to the excavation failures frequently caused by rainstorm events featuring different rainfall patterns, especially those in erodible sandy strata. To explore the characteristics and failure mechanisms of both sloped shallow and multi-propped deep excavations in sandy strata associated with intense rainfall, this study employed a computational fluid-dynamic (CFD) and discrete-element-method (DEM) coupling method (CFD-DEM), which was validated by a typical failure of a sloped excavation triggered by heavy rainfall in China. Subsequently, extensive parametric studies were carried out to investigate the effects of rainfall amounts and patterns on the excavation responses. It was disclosed that for a sloped shallow excavation retained by soil nails, rainfall infiltration caused initial instability at the slope toe and then incurred sliding failure along a linear slip surface; regarding a multi-propped deep excavation, sand flowing failure occurred and its basal strata underwent evident upward movements, accompanied by kicking out of the embedded retaining wall. With increasing of precipitation and variation coefficient of rainfall patterns, excavation deformations increased and the rainfall-induced primary displacement zone (PDZ) expanded as well. Finally, simplified solutions were proposed to estimate the distribution of PDZ.

Effects of drilling parameters on stress relief performance during mining

Abstract This study investigated the effects of borehole diameter and borehole interval on the stress relief performance of coal seams during mining. A discrete element numerical model was established based on the Voronoi and block models, and the stress relief performance was investigated in terms of axial stress, vertical displacement, and plastic zone development using the control variates method. The results showed that a decrease in the distance from the workface was accompanied by an increase in the effects of mining, the stress concentration, and the vertical displacement of the roof. Coal mining had positive effects on fracture propagation in front of the workface. As the borehole interval increased, the density of boreholes in the coal seams decreased, reducing the stress concentration and fracture propagation in front of the workface. The stress relief performance of the boreholes in the coal seams was improved at an borehole interval of 8 m. However, as the borehole diameter increased, the stress concentration near the boreholes decreased, reducing the effects of the workface mining on stress relief through the boreholes. Meanwhile, increasing the borehole diameter decreased the vertical displacement of the roof but exacerbated fracture propagation in front of the workface, which improved the stress relief performance of the boreholes in the coal seams. This study provides a reference for arranging boreholes in coal seams during mining.

The “suevite” conundrum, Part 2: Re‐examining the type locality at the Ries impact structure, Germany

AbstractOne of the most common types of allochthonous impactite produced in hypervelocity impact events is impact breccia that contains melt particles. In numerous terrestrial hypervelocity impact structures such melt‐bearing breccias have been termed “suevite,” after the type locality at the Ries impact structure, Germany. Despite its widespread occurrence, the origin, emplacement, and classification of suevite remains debated. In this contribution, we re‐examine the nature and origin of suevite at the Ries impact structure. The results of new field and laboratory investigations, when combined and synthesized with results from previous studies, lead to a multi‐stage model for the origin and emplacement of allochthonous impactites during the Ries impact event. Following the creation of a transient cavity the so‐called Bunte Breccia and “megablocks” were emplaced via ballistic sedimentation and subsequent radial flow during the excavation stage to form a continuous ejecta blanket. At the end of the excavation stage, a mixture of melt and lithic fragments formed a lining to the transient cavity and it is this material that later became the crater, dike, and outer suevite (OS) units. The crater suevite represents the material from the displaced zone of the transient cavity that was transported and mixed but never left the cavity. The emplacement of dike suevite occurred during the modification stage as the crater suevite was intruded into fractures in the underlying crater floor. The OS and rare impact melt rocks overlying the ballistic (Bunte Breccia) ejecta deposits were emplaced as outwards‐directed ground‐hugging flows largely during the modification stage of crater formation. The OS flows varied both spatially and temporally in terms of the flow characteristics, from being dominated by solid particles and gas (cf. pyroclastic density currents) to a mixture of solid particles, liquid (impact melt), and minor gases (i.e., particulate impact melt‐rich flows). These particulate impact melt‐rich flows dominated by far. Minor “fallback” of material from an ejecta plume is evidenced by accretionary lapilli in the Nördlingen 1973 core. In summary, allochthonous impactites at the Ries impact structure are not unusual but are consistent with observations from other terrestrial and planetary craters, where melt‐rich impactites overly ballistic ejecta deposits both outside and inside crater rims and where melt‐rich impactites occur in crater interiors.

Fracture behavior of environmentally friendly high-strength concrete using recycled rubber powder and steel fibers: Experiment and modeling

Ultra-high-performance concrete (UHPC) is becoming increasingly popular for its exceptional mechanical properties but suffers from high cost and limited ductility. To overcome these limitations, this study explores the development of cost-effective and ductile Environmentally friendly High-strength Concrete (E-HSC) by incorporating recycled steel fiber (RSF) and rubber powder into UHPC. Fracture properties and crack propagation behavior were examined through three-point bending fracture tests on notched beams with varying rubber powder (0 %, 5 %, 20 %, 35 % and 50 %) and recycled steel fiber (1 %, 2 % and 3 %) content. Digital Image Correlation method was Used to Measure Crack mouth opening displacement and Fracture process zone in the Fracture Process of E-HSC of the E-HSC were analyzed using the digital image correlation method. Results revealed that E-HSC with 5 % rubber powder exhibited superior fracture energy and double-K fracture toughness. The use of rubber powder and RSF enhances the ductility of concrete, with the characteristic length consistently increasing as the content of rubber powder and RSF increases. Additionally, a softening constitutive model was proposed to evaluate the fracture performance of E-HSC based on rubber powder and recycled steel fiber content. This research provides experimental data and theoretical insights for developing resilient E-HSC suitable for applications in significant structures.

Ecological displacement in a Rocky Mountain hybrid zone informs management of North American martens (Martes)

ContextParapatric sister species are ideal for tests of ecological interactions. Pacific (Martes caurina) and American pine (M. americana) martens are economically and culturally valuable furbearers that hybridize in the north-central Rocky Mountains. Despite preliminary evidence of biased introgression, the hybrid zone has been geographically stable for 70 years, but interspecific ecological interactions have yet to be examined in detail.ObjectivesWe test whether ecological interactions may influence the outcome of hybridization in this system. To that end, we estimate the fundamental niche of each species and gauge how suitability landscapes change when the two species are in contact.MethodsWe genotyped > 400 martens from the Rocky Mountain hybrid zone to diagnose individuals to species-level and identify putative hybrids. We then built range-wide ecological niche models for each species, excluding individuals in the hybrid zone, to approximate their respective fundamental niches. Those models were projected into the hybrid zone and compared with niche models trained on individuals within the hybrid zone to assess how niche dynamics change when the species are in sympatry.ResultsThe fundamental niche of each species differed significantly, while the hybrid zone was equally suitable for both. Niches of each species based on models built within the hybrid zone showed that Pacific martens utilized significantly less suitable habitat than expected based on their range-wide fundamental niche, suggesting that species interactions shape local hybridization. We detected few admixed individuals (12%), with no evidence of directional (sex or species) biases. Interstate-90 further acts as a major dispersal barrier.ConclusionsNorth American martens are currently managed as a single species by some state agencies, yet significant ecological and genetic differences indicate they should be managed separately. The observed ecological displacement of Pacific martens by American pine martens may partially explain the mixed success of historical, mixed-species wildlife translocations and cautions such translocations in the future. Landscape-scale consideration of ecological dynamics, in addition to molecular compatibility, will be essential to the success of future translocations.

48‐2: Research on Mechanical Simulation of Flexible AMOLED Module Bottom Frame

With the development of science and technology and consumers' pursuit of high screen ratio, the frame of terminal flagship products has become an important research direction. However, the thinner the bottom frame is, the higher probability of metal wire breakage in bending area. In this paper, we use finite element analysis to simulate the whole bending process of bottom frame, study the influence of bending path, indenter displacement, bending radius and buffer zone on metal wire, summarize the failure mechanism, which provides theoretical basis for fault analysis, stacking structure design and smaller radius design.

Failure characteristics and fracture mechanism of overburden rock induced by mining: A case study in China

This study employs similar simulation testing and discrete element simulation coupling to analyze the failure and deformation processes of a model coal seam's roof. The caving area of the overburden rock is divided into three zones: the delamination fracture zone, broken fracture zone, and compaction zone. The caving and fracture zones' heights are approximately 110 m above the coal seam, with a maximum subsidence of 11 m. The delamination fracture zone's porosity range is between 0.2 and 0.3, while the remainder of the roof predominantly exhibits a porosity of less than 0.1. In addition, the numerical model's stress analysis revealed that the overburden rock's displacement zone forms an 'arch-beam' structure starting from 160 m, with the maximum and minimum stress values decreasing as the distance of advancement increases. In the stress beam interval of the overburden rock, the maximum value changes periodically as the advancement distance increases. Based on a comparative analysis between observable data from on-site work and numerical simulation results, the stress data from the numerical simulation are essentially consistent with the actual results detected on-site, indicating the validity of the numerical simulation results.

Dynamic simulation of immiscible displacement in fractured porous media

Investigating immiscible displacement in fractured porous media is essential for understanding the two-phase flow behavior within pores and fractures. In this work, a three-dimensional pore-fracture network model was developed to address the influence of fracture on flow patterns and to characterize fracture-matrix crossflow under different flow conditions. Sensitivity studies at a wide range of viscosity ratios and capillary numbers underscored that fracture significantly influenced flow patterns in the capillary fingering zone. Fracture with an advantageous path effect in the displacement direction caused a shift in the boundary of capillary fingering zone toward an increase in capillary numbers. As fracture aperture decreased and aspect ratio increased, there was a discernible decline in the crossflow rate. When fracture aperture equaled average matrix throat diameter, fracture lose advantageous path effect in compact displacement zone but retained it in viscous fingering and capillary fingering zones. Distinct matrix-fracture crossflow development processes were observed in different zones: in cross zone, following displacement breakthrough, the crossflow underwent a “long-term” process to attain stability. Viscous fingering zone promptly achieved stability post-breakthrough, whereas both capillary fingering and compact displacement zones had already reached a stable state before breakthrough. Nonlinear variations in breakthrough saturation were observed in the cross zone between compact displacement and capillary fingering zones. The control process of immiscible displacement exhibited variability under different flow conditions: compact displacement zone was characterized by matrix dominance, viscous fingering zone was jointly controlled by matrix displacement and fracture-matrix crossflow, and capillary fingering zone was primarily governed by fracture-matrix crossflow. These findings enhance scholarly comprehension of immiscible displacement behavior in fractured porous media.

Quantitative characterization of imbibition in fractured porous media based on fractal theory

In low-permeability reservoirs, such as shale and tight sandstone, imbibition is an important mechanism for enhancing oil recovery. After hydraulic fracturing treatment, these reservoirs create a network of fracture pathways for fluid flow. Therefore, understanding the imbibition mechanisms in fractured porous media and quantitatively characterizing oil–water distribution are crucial for the development of low-permeability reservoirs. In this study, a mathematical model of two-phase flow in porous media with branching fractures was established. The phase-field method was employed to track the oil–water interface, and quantitative characterization of imbibition was conducted based on fractal theory, and the effects of wetting phase injection rate, the number of disconnected fractures, fracture spacing, and fracture morphology on imbibition in branched fracture porous media were discussed. The research findings indicate that in branched fracture porous media, both co-current and countercurrent imbibition processes occur simultaneously, and there exists a diffusion interface layer with a certain thickness at the oil–water interface. The hydraulic pressure generated by the wetting phase injection rate provides the driving force for imbibition oil recovery, but it also affects the contact time between the wetting and non-wetting phases. The presence of disconnected fractures hinders the propagation of hydraulic pressure, reducing the effectiveness of imbibition. The imbibition displacement zone is limited and occurs only within a certain range near the fractures. As the number of branching fractures increases, the channels for the wetting phase to enter matrix pores are enhanced, resulting in higher efficiency of imbibition displacement of the oil phase. The results of this research can provide guidance for the design of fracturing programs and recovery prediction in low-permeability reservoirs.

Assessing prestressed anchor cable support as ore pillar alternatives in stope span expansion: A case study

In large diameter long-hole (LDL) stopes, ore pillars are often set up in the rock drilling chamber to expand the span. However, after the ore pillars are blasted along with the stope, the stability of the roof is difficult to control, and collapse often occurs. This study introduced the idea of employing PAC support technology to replace the traditional ore pillar support and conducted site investigations, theoretical analysis, numerical simulations, and field tests to develop a technology for expanding the span of LDL stope based on prestressed anchor cable (PAC) support. Following a detailed investigation of pillar-supported LDL stope roof collapse events and geological conditions, a mechanical model for the stress arch considering the lateral stress coefficient was developed combining the failure characteristics and deep conditions, and the inverse relationship between the lateral coefficient of ground stress and the height of the stress arch above the opening was determined. Numerical simulation results demonstrate that the elliptical parabolic stress arch mechanical model has been verified, and PAC effectively controls roof stability, as evidenced by displacement and plastic zone response. Field tests were carried out utilizing PAC support, and monitoring results affirm the PAC support system's efficacy in stabilizing the roof. Using PAC to replace ore pillars resulted in a remarkable 29.8 % improvement in blast hole drilling efficiency and reduced ore dilution rate within the stope from 22.3 % to 14.2 %. This study serves as a reference for addressing analogous challenges in other mining operations.

Case study on the secondary support time and optimization of combined support for a roadway under high in-situ stress

Roadway support can effectively improve the stability of roadway excavation and ensure the safety of underground mining. This study investigates the secondary support time and parameter optimization of combined support for a deep roadway in the stage of resource replacement in the Huize lead–zinc mine in Yunnan Province, China. The aim of this study is to increase the stability and safety of the roadway and decrease the cost of support. Research on support methods and failure modes has shown that under the action of high in-situ stress in deep mining, the surrounding rock of the roadway exhibits obvious rheological phenomena. The change in the radial displacement of the roadway is combined with creep tests of the main exposed surrounding rock to determine the secondary support time. Numerical simulations and orthogonal tests are utilized to optimize the support parameters in terms of the roof subsidence, floor heave displacement, side displacement, and plastic zone by analyzing the effects of the sprayed concrete thickness, bolt length, bolt row spacing, and bolt diameter on the support results. The proposed secondary support time and combined parameters can provide a reference for roadway support in similar strata.

Characteristics and genesis of the Zhongnan Fault Zone in the South China Sea oceanic basin: Insights from an integrated analysis of multibeam bathymetric and 2D multichannel seismic data

The Zhongnan Fault Zone (ZFZ) is a large-scale tectonic belt in the South China Sea (SCS) oceanic basin and plays an important role in the formation and evolution of the basin. Despite numerous studies over the past few decades, debates persist regarding its location, orientation, nature, time of activity, and genesis. In this study, we evaluate our findings on the characteristics and origin of the fault zone through an integrated analysis of multibeam bathymetric and 2D multichannel seismic data. Our results reveal the ZFZ as a fault zone approximately 400 km long and 50–90 km wide, situated between the east subbasin (ESB) and southwest subbasin (SWSB) of the SCS. The fault zone is oriented N8°W, roughly perpendicular to and laterally displacing the relict spreading center and related spreading lineaments. Bounded by discontinuous linear seamounts, the fault zone comprises two V-shaped subparallel pull-apart basins and a separating basement high. Steeply dipping (>60°) normal basement-involved faults bound these pull-apart basins, forming typical negative flower structures. Numerous northeast-oriented en-echelon linear bathymetric highs within the fault zone are identified as secondary antithetic shears (P′ shears). These shears are characterized by their orientation relative to the principal displacement zones defined along the pull-apart basins. The ZFZ exhibits differences from the adjacent subbasins in water depth, basement burial, stratal thickness, and seismic stratigraphic characteristics. Five seismic sequences (S1–S5 upward) in the ZFZ and nearby ESB and SWSB are defined, dating to the Early Miocene synspreading (S1) and the Middle Miocene to Recent postspreading (S2–S5) stages, respectively. The difficulty in correlating seismic facies in sequences S1–S3, compared with the comparable seismic facies in sequences S4–S5 between the ZFZ and adjacent subbasins, suggests a horizontal displacement during the synspreading and early postspreading stages. We propose that the ZFZ functioned as a right-lateral transform fault zone during the synspreading period (the Early Miocene, approximately 24–16 Ma) of the SWSB and transitioned into a left-lateral strike-slip fault zone during the successive early postspreading period (the Middle-Late Miocene, approximately 16–5.3 Ma).

Evaluation of buoyant action of groundwater and surface water interaction on pit slope stability using hydrogeological-stratigraphic-structural assessment within the Kawere catchment of the Nsuta mine

ABSTRACT In open-pit mining operations where activities are conducted below water table or close to surface water bodies, the mine is potentially faced with dewatering and slope stability challenges. Appropriate evaluation of slope stability to obtain adequate slope safety factor has continuously been the centre of geotechnical research locally and internationally. This paper evaluates the influence of buoyant action propagated by groundwater and surface (GW-SW) interaction on pit slope designed in multi-layered fractured rock with complex hydrology using Hydrogeological-Stratigraphic-Structural Assessment (HSSA) at the Nsuta Manganese Mine in Ghana. LEM analyses of the Pit C-western slope estimated an overall factor of safety (FOS) of 1.1, probabilities of failure (POF) of 7.5% and the reliability index (RI) of 1.4 in the slope stress field. However, when the groundwater was introduced, the slope FOS was reduced to 0.13, POF of 100.0% and (RI) of 0.00 indicating failure. FEM numerical model points to the location of maximum shear strain and total displacement in the argillite zone within the rock mass. The FEM seepage analysis model estimated groundwater pore pressure data along the critical slide surfaces from the crest of the slope to the bottom of the rock slope ranging between 250 kPa and 4250 kPa with an average pore pressure of 2250 kPa within the pit slope. This proposed HSSA approach used in the study provides innovative insights into the percentage failure contribution of the individual lithologies to the overall combined lithological susceptibility of the slope under stress and groundwater failure mechanisms, pointing out Ru ratio in pit slope stability estimation as inadequate.

Patterns of glacio‐isostatic adjustment in mainland Scotland: new data from western central Scotland, proximal to the zone of maximum rebound

The results of geomorphological mapping and survey of Lateglacial and Holocene displaced shorelines in the Clyde estuary and around Loch Lomond, western central Scotland are described. On the basis of morphology, sedimentology, altitude and radiocarbon dating, four discrete shorelines are identified and are correlated with previously identified Scottish displaced shorelines. The shoreline formerly referred to as the Main Postglacial Shoreline is renamed the Menteith Shoreline. This body of data, combined with data on displaced shorelines for Scotland as a whole has been analysed using Gaussian quadratic trend surface analysis in order to determine the centre of glacio‐isostatic displacement for each shoreline. These Gaussian models of palaeo‐relative sea‐level suggest that the zone of greatest displacement lay NNW of Loch Lomond in the Lateglacial then moved SSE to the region of Loch Lomond during the Holocene and the Clyde in the Late Holocene. The factors responsible for the movement of the zone of greatest uplift are discussed, including temporal variations in the ice‐sheet thickness, variations in water load in the adjacent sea‐lochs and neotectonic processes. Comparison is made with glacial isostatic adjustment (GIA) models. A sensitivity analysis has been carried out on the use of Gaussian trend surface analysis glacio‐isostatic modelling and this is included in the research evaluation, and reported in full in the Supporting Information files, along with the raw data used throughout this study.

A cross-sectional study of macular displacement after macular hole surgery with ILM peeling in patients with idiopathic macular hole.

To examine the retinal displacement and change in mean superficial foveal avascular zone (FAZ) after successful closure of macular hole (MH) with vitrectomy with internal limiting membrane peeling (ILM) and gas tamponade. A total of 45 patients with idiopathic MH who underwent 23G pars plana vitrectomy with ILM peeling and tamponade with 20% SF6/14% C3F8 were included. Follow-up visits were performed at 2, 4, and 8 weeks. OCT and OCT-A scans were performed along with detailed ocular examination. Distance between optic disc and an easily identifiable vascular bifurcation nasal and temporal to fovea, FAZ, was noted. Chi-square test (categorical data) and Mann-Whitney U test and t tests for other parameters were performed for statistical analysis. The mean displacement (µm) of an easily identifiable vascular bifurcation in the nasal quadrant was 96.58 ± 36.55 at 8 weeks and in the temporal quadrant was 273.07 ± 85.51 at 8 weeks. The change was statistically significant in the temporal quadrant (P = <0.001). The mean BCVA changed from a minimum of 0.08 at the preoperative timepoint to a maximum of 0.23 at 8 weeks (P = <0.001). The mean FAZ area (mm²) decreased from a maximum of 0.37 at the preoperative timepoint to a minimum of 0.19 at 8 weeks (p = <0.001). The retina in the temporal quadrant is displaced significantly more than nasal quadrant after successful closure of macular hole. The mean superficial FAZ also decreases suggesting a centripetal movement of the foveal tissue postoperatively.