Shear Front Research Articles

Sedimentation and transformation of heavy metals during the transport from the Yellow River estuary to the sea: Evidence from surface sediments of the Yellow River subaqueous delta

Estuarine and coastal areas are one of the ultimate sinks for terrestrial heavy metals which play a vital role on the aquatic ecosystem. This study examined heavy metals contents and speciations in Yellow River subaqueous delta surface sediment, to characterize their sedimentation and transformation during transport from estuary to the sea. The results showed that higher concentrations were found in the seaward and the shear front affected areas. The surface sediments were generally not contaminated by heavy metals, except for Cd was highly enriched, while the post-standardization spatial distribution reflected the effect of estuarine processes as a “filter” that effectively intercepting heavy metals. The dominated phase was residual fraction for Cr, Cu, Zn, Cd, while reducible fraction for Ni and carbonate fraction for Pb. The transformation of heavy metal species was mainly influenced by the changes in the sediment components such as carbonate minerals, organic matter and FeMn oxides.

Impact of tidal shear fronts on terrigenous sediment transport in the Yellow River Mouth: Observations and a synthesis

A tidal shear front (TSF) can be defined as an obvious horizontal gradient of flow velocity formed by opposing tidal currents (reversed TSF) or same-direction tidal currents (homogenous TSF) on both sides of the front with limited impact by river runoff. Observational and modeling studies have been conducted to investigate the impact of a reversed TSF on the transport of freshwater and sediment in the Yellow River Mouth (YRM). The reversed TSF existence period is only about 40% of a tidal cycle (around slack of flood and ebb); however, when this front disappears (around maximum flood and ebb), sediment transport across the frontal zone is still rare. This suggests that the dynamic mechanism of cross-frontal sediment transport in a tidal cycle remains unclear. In this study, synchronous observations of sea current and suspended sediment concentrations along the river mouth profiles at the YRM in 1995, 2003, and 2019 were used to investigate the long-term variation characteristics, mechanisms, and impacts of the TSF on cross-frontal sediment transport. The results indicate that in addition to the reversed TSF, there are also homogenous TSF during flood and ebb tides, with the ebb homogenous TSF being more significant due to tidal asymmetry in the YRM. The ebb homogenous TSF is located between shallow shoals and the slopes of the subaqueous delta front and lasts for about 3 h around the maximum ebb. Its maximum shear strength is similar to that of the reversed TSF, and the formation mechanism is also similar. The presence of the ebb homogenous TSF reduces the efficiency of cross-frontal sediment transport during the ebb. The reversed and homogenous TSFs alternately block sediment moving towards the sea. Thus, terrigenous sediment is difficult to cross the frontal zone to the central Bohai Sea by tidal currents solely. Over the past two decades of low discharge, with the Yellow River implementing artificial water and sediment regulation, the homogenous TSF during the ebb tide has become more and more important and cannot be neglected for cross-frontal sediment transport under normal conditions. Furthermore, from a long-term perspective, the shear strength of the TSF is positively correlated with the distance of river mouth siltation into the sea. Additionally, salinity and turbidity gradients are also positively correlated with the shear strength in the estuary. This indicates that the blocking of cross-frontal sediment transport by the TSF is a key process in river-sea interaction in the YRM.

Dynamic transport of particulate organic carbon in the Yellow River during dam-orientated Water-Sediment Regulation

The Yellow River has experienced prolific environmental changes from dam regulations that have significantly altered the downstream hydrologic regime, and transport of sediment and POC within the river-coast continuum. Here, we investigated the contrasting changes in sources and transport of POC from the lower Yellow River to the river mouth, at two different stages (e.g., Water vs. Sediment regulation) of dam operation - during the period of Water-Sediment Regulation Scheme (WSRS). Riverbed erosion downstream the Xiaolangdi Dam contributed the POC with more enriched δ13C stable isotopic values, along with those more isotopically depleted POC from riparian floodplains and the reservoir at the Water-regulation stage, when clear water was released from the reservoir. At the Sediment-regulation stage, muddy floodwaters were released, while soil-derived POC and fine-grained sediment released from the reservoir became dominant with evidently increasing POC content. The dispersal and distribution of river-laden POC at the river mouth were primarily modulated by the plume dynamics, as remotely impacted by dam regulation, in combination with the dynamic shear front. As a result, the POC distribution was confined within 10 km off the river mouth due to the rapid deposition of coarse-grained sediments. In contrast, the fine-grained sediment and more isotopically depleted POC, from modern sources (e.g., C3 vascular plant), were delivered to the far-field plume region. POC transport along the Yellow River-Estuary continuum exhibited complex behaviors, coupled with natural and dam-regulated drivers, on a variety of spatial-temporal scales. These findings provide important insights into dynamic linkages on how coastal carbon cycling can be significantly altered, remotely from the upstream dam regulations, in a large global river system.

Using high-speed ultrasound to visualize dynamic jamming of dense suspensions

A remarkable property of concentrated, or dense, suspensions comprising nanometer- to micrometer-size particles in a liquid is their ability to transform from a liquid-like to a solid-like state under applied stress. This jamming phenomenon can be triggered by impact at the surface of a dense suspension and generates a shear front that propagates into the bulk of the material. Tracking and visualizing such front is difficult because suspensions are typically opaque optically, and the front can propagate at several meters per second. This talk will discuss high-speed ultrasound imaging (10 000 frames per second) to extract the flow field associated with the front propagation and visualize the associated shear jamming process. Unlike densification in dry granular media, jamming by shear does not involve significant changes in the local particle fraction while driving the transition to solid-like behavior. On the basis of these findings, we discuss ideas that link the transient stress response of dense suspensions to current theoretical models, which almost exclusively focus on steady-state shearing conditions.

The effects of flow pulses on river plumes in the Yellow River Estuary, in spring

Abstract In this paper, an extended three-dimensional (3D) model of the Yellow River Estuary (YRE) is established. It is based on a Delft 3D shallow-water high-resolution hydrodynamic model. The model is calibrated and verified by field observation data, which ensures its stability and accuracy, and provides a better simulation of the river plume in the estuary under different flow inputs. Since 2009, the spring flow pulse of the Yellow River can be divided into four types. The strong flow pulse is more conducive to the extension of the low salinity zone (LSZ). Doubling the peak discharge of pulse flow increases the LSZ area by 60%. The retardation time of salinity change in response to the flow pulse in estuary waters is weakly affected by the flow pulse intensity. The difference in shear front between the spring tide and the neap tide is the main dynamic mechanism contributing to the different retardation times. The average retardation time is 73 h during the spring tide and 55 h during the neap tide. In order to reduce the estuary salinity, it is suggested that the optimal time for the peak value of flow pulse in the river mouth is during the neap tide.

The impact of Holocene interactions among climate, ocean current, and shear front factors on fine sediment dispersal in the central South Yellow Sea

The South Yellow Sea (SYS) is strongly influenced by large amounts of sediment input from surrounding rivers, but the dispersal patterns of these sediments, especially how they accumulate in the central Yellow Sea mud (CYSM) region, have not been well illustrated. Here, we present a detailed temporal variation record of the clay mineral compositions from core YSC-10 of the northern SYS near the western margin of the CYSM, trying to investigate sediment provenance and to discuss transport processes occurring during the Holocene. The clay mineral assemblages of core YSC-10 mainly consist predominantly of illite (68 ± 3%), followed by chlorite (15 ± 2%) and kaolinite (10 ± 2%), with scarce amounts of smectite (6 ± 3%). Combined with published data, our results suggest that the fine sediments of core YSC-10 are most likely a mixing product of the Huanghe (Yellow River), Changjiang (Yangtze River) and Korean Peninsula small river sediments, with notable temporal changes. During 8.4–6.4 ka, the Huanghe sediments from the Bohai Sea flowed directly into the SYS and played major roles in the sedimentation therein. In addition, as the modern ocean circulation pattern was formed ∼6 ka, the ocean front developed along the Shandong Peninsula coastal area of the SYS, which would have prevented the dispersal of the Huanghe sediments to the CYSM. The Changjiang sediments delivered by the diluted water replaced those from the Huanghe as the main source of the CYSM during the period of 6.4–4.2 ka. After 4.2 ka, the coastal shear front weakened and moved seawards due to the weakening and eastward shift of the Yellow Sea Warm Current (YSWC) in winter and the weakening and shrinking of the Yellow Sea Cold Water Mass (YSCWM) in summer. The Huanghe sediments seem to have increased and fluctuated frequently to core YSC-10 since then. Our study thus highlights that the coastal shear front may have played an important role in the source-to-sink processes of the SYS.

In Situ Generated Shear Bands in Metallic Glass Investigated by Atomic Force and Analytical Transmission Electron Microscopy

Plastic deformation of metallic glasses performed at temperatures well below the glass transition proceeds via the formation of shear bands. In this contribution, we investigated shear bands originating from in situ tensile tests of Al88Y7Fe5 melt-spun ribbons performed under a transmission electron microscope. The observed contrasts of the shear bands were found to be related to a thickness reduction rather than to density changes. This result should alert the community of the possibility of thickness changes occurring during in situ shear band formation that may affect interpretation of shear band properties such as the local density. The observation of a spearhead-like shear front suggests a propagation front mechanism for shear band initiation here.

The Cross‐Shore Component in the Vertical Structure of Wave‐Induced Currents and Resulting Offshore Transport

AbstractA comprehensive field survey was conducted, and a numerical model based on the Princeton Ocean Model was established to investigate the vertical structure of current induced by surface waves and identify its effect on sand loss from a beach. Previous studies have examined wave‐induced longshore transport, whereas this study focused on cross‐shore transport caused by waves. The introduction of vertically dependent radiation stress revealed that wave‐induced vertical gyres existed with onshore and offshore flows in the upper and lower layers, respectively, besides the well‐known wave‐induced longshore flow. It was found that the vertical gyres were caused by the onshore wave force (a gradient of radiation stress) in the upper layer and the offshore wave force usually existed in the lower layer, as well as the horizontal imbalance of local wave force. The locations of wave‐induced vertical gyres were found to correspond to the location of sediment erosion, and thus the lower part of the vertical gyres drove the offshore transport of eroded sediment. Moreover, the vertical gyres were located in areas with a highly variable topographic gradient (e.g., at a bar), and their driven offshore currents (undertow/return flow) extended far beyond the surf zone. The topographic slope had a profound effect on the vertical structure. Numerical experiments showed that an extended breakwater from the eastern headland of the bay could prevent sediment from being eroded. Furthermore, the shear front at the rim of a horizontal gyre could retain suspended sediment in the center of the gyre.

Holocene Climate Modulates Mud Supply, Transport, and Sedimentation on the East China Sea Shelf

AbstractShelf mud is an important sink for fluvial sediment, and it is sensitive to variations in river discharge and ocean circulation, which are significantly influenced by climate change. However, the evolution of shelf mud in response to climate change during the Holocene is poorly understood. Here, we present high‐resolution sedimentary records of heavy minerals and mass accumulation rates (MARs) from the East China Sea shelf to study the response mechanisms of the Holocene shelf mud supply, transport, and sedimentation to the climate‐driven variations in fluvial discharge and ocean currents. The results indicate that the shelf mud primarily originates from the Changjiang (Yangtze) River and has been mainly transported by wind‐driven longshore currents in suspension since approximately 8.0 ka. A comparison of the MARs with several shelf mud sedimentation‐rate records and climate changes during the Holocene on millennial timescales showed that strong (weak) precipitation in the river basin, which is positively linked with Asian summer monsoon and El Niño‐driven storms, could intensify (weaken) the fluvial sediment supply, thereby increasing (decreasing) the shelf mud deposition flux. On multicentennial timescales, changes in the relative intensities of different ocean currents due to climate oscillations during the Holocene could generate frequent migrations of the current shear front (a hydrodynamic barrier), which has trapped an abundance of suspended materials on the shoreward side and resulted in rapid mud sedimentation (~2.3 g/cm2/year) at different sites during different periods. Therefore, our study highlights that the Holocene shelf mud evolution responds sensitively to climate changes on different timescales.

Hydrometeor Budget of the Meiyu Frontal Rainstorms Associated With Two Different Atmospheric Circulation Patterns

AbstractCharacteristics of hydrometeor budget and the microphysical processes responsible for heavy precipitation are studied based on the WRF model simulations of two representative Meiyu frontal rainstorms that are associated with two distinct atmospheric circulation patterns. Case 1 is characterized by the coupling of the Eastward Propagating Mesoscale Vortex (EPMV) and Meiyu front, while Case 2 is dominated by the interaction between the Low‐Level Wind Shear (LLWS) and Meiyu front. The temporal and spatial characteristics of the hydrometeor budget are validated against observations and assimilation products including those obtained during the 2018 Integrative Monsoon Frontal Rainfall Experiment (IMFRE) campaign and discussed in the context of contrasting the precipitation intensification and dissipation stage. Specifically, the ice‐dependent cloud processes, rather than the liquid‐dependent cloud processes, are predominantly responsible for the variation of precipitation. These terms include the deposition from water vapor to the ice phase hydrometeors, the accretion from cloud liquid water to the ice phase hydrometeors in the upper troposphere, and the melting of the ice phase hydrometeors into raindrops in the mid‐lower troposphere. Then three major ice cloud conversion pathways and two minor warm cloud conversion pathways for the formation of raindrops are extracted from the overall microphysical processes active in both Case 1 and Case 2. One of the key findings is that ice‐dependent cloud processes are significantly more active in the case characterized by the coupling of EPMV and Meiyu front, and this difference is at least partly explained by the differences in dynamical and thermodynamic conditions dominated by the circulation patterns.

Storm-induced hydrodynamic changes and seabed erosion in the littoral area of Yellow River Delta: A model-guided mechanism study

Morphological evolution of large river deltas is highly vulnerable to extreme storm events due to insufficient sediment supply. As an abandoned delta lobe, the coasts along the northern Yellow River Delta (YRD) and Gudong Oil Field have recently suffered serious erosion due to extreme storm events and become increasingly vulnerable. In this study, a well validated and tested Delft 3D module by the observing hydrodynamic and sediment data to simulate the hydrodynamics and seabed erosion during a storm event in the littoral area of YRD. Observed wave, current and sediment data under both fair-weather and storm conditions were collected in the study area and used to validate the model. The results indicated that the model can reproduce well the hydrodynamic and sediment transport processes. A series of numerical experiments were carried out to examine the hydrodynamic changes and sediment transports. In the numerical experiment of normal condition, there is hardly any sediment transport off the YRD. The numerical experiment of storm condition showed that storms enhanced tidal residual currents, weakened tidal shear front, and significant wave heights up to 2 m, considerably intensified the sediment resuspension and dispersal. The local sediment resuspension due to the increased wave-induced bottom stress promoted the sediment plume to expand to the central area of Laizhou Bay, which seemed to provide sediment source for offshore and southward transport. During the storm, the active nearshore sediment resuspension provided sediment source for offshore and southward transport. The intensive dynamics and sediment transport under storm conditions caused significant changes in seabed erosion and siltation. The main erosion occurred off the Gudong and northern YRD, while the main siltation appeared in the central area of Laizhou Bay. No significant recovery after a storm and frequent strong winds have an accumulative effect on the erosion, which is very likely to dominate the erosive states of the YRD coast in the future.

Impact of river discharge on hydrodynamics and sedimentary processes at Yellow River Delta

During the Anthropocene, regulating river discharge by high dams may have met the need for water demands in river basins, but resulted in carrying less freshwater and sediment to the sea, inducing land degradation and shoreline retreat in worldwide mega-river deltas. In land-ocean interaction, tide response to water discharge changes plays an important role and is crucial for the river-laden sediment transfer and dispersal, affecting both nearshore and estuarine deposits. The Yellow River Delta (YRD), which is under an increasing pressure of the new discharge regime of the Yellow River, has undergone drastic changes in terms of sediment dynamics and morphologic evolution. To gain a better understanding of the overall fluvial and marine hydrodynamics and morphodynamic processes in the YRD, in this study, a full-scale numerical model is built to investigate the interaction and impacts of changing environmental forcing and dynamics on flow and sediment transport in the estuary of YRD and its adjacent coasts. The results show that the river discharge strongly affects the tidal dynamics and morphology of the delta, particularly in the close vicinity of the outlet and the intertidal zone. Tidal constituents M2 and K1, which are the most significant ones in the YRD, are found to be noticeably affected with a decreasing trend when the river discharge increases. The model results also indicate that river discharge affects the location and intensity of the shear front that occurs in the nearshore areas of the YRD. Increasing the river discharge can induce a seaward movement of the shear front, reduce its width and concentrate its shear intensity. It is found that the reverse of the flow direction at each side of the shear front and strong longshore tidal current can act as a barrier for the sediment dispersal process by keeping suspended sediment in the inner zone, thus to form a particular sediment deposition zone and the depo-center.

Shear localization and its dependence on microstructural length scales in metallic glass composites

Extrinsic approaches for the pursuit of ductility in metallic glasses have involved the introduction of a ductile crystalline phase to inhibit the propagation of a dominant shear front through the amorphous matrix material. Using nanoindentation, we explore the role of crystalline inclusions in metallic glass matrix composites with a focus on the onset of shear banding in the amorphous matrix and the nature of shear band propagation using the propensity for localization and its dependence on indentation strain rate. When indentation length scales are favorable to distribute strain to both the crystalline dendrites and amorphous matrix, we reveal a reduction in the number of detectable displacement bursts and an accompanying decrease in the magnitude of individual depth excursions from shear banding. A decrease in the stress at the onset of shear banding is also correlated with shear band trajectories interacting with the amorphous-crystalline interfaces (ACIs). Our results thus demonstrate that ACIs reducing the activation barrier for shear banding combined with dendrites arresting propagating shear fronts act to enhance the nucleation rate and in turn, promote a more homogeneous plastic response.

High-resolution observations of a shear front in a tidal channel

The characteristics of a shear front system in a tidal channel have been investigated through a field study. High-resolution sampling, including three-dimensional measurements of current, temperature, salinity, and turbidity, was performed on repeated transects across the frontal zone both with fronts apparent and with fronts absent. The density measured using conductivity/temperature/depth sensors provides a field proof that the shear front is present whether a density gradient exists. It is distinguishable from conventional buoyant shear fronts, which require a strong along-channel density gradient. The velocities measured using an Acoustic Doppler Current Profiler (ADCP) and trapping Global Position System (GPS) drifters indicate that shear front evolution has a four-stage dynamic process in a tidal cycle: (1) a directional shear front of shoal-flood and channel-ebb during the slack before flood and early flood, (2) a speed shear front of shoal-quick and channel-slow after the early flood, (3) a directional shear front of shoal-ebb and channel-flood during the slack before ebb and early ebb, and (4) a speed shear front of shoal-slow and channel-quick ebb during the late ebb. Thus, the velocity shear, a variation in the current speed and direction on either side of the front, is the generation mechanism of the observed shear front system. It is caused by the unequal tidal durations between deep channels and shallow shoals in the channel discussed herein. The Coriolis effect is found to be negligible through the momentum balance analysis. The unequal tidal durations can be caused by the following alternative mechanisms, according to the analysis and model simulation: (1) differential friction, owing to the steep bathymetry between the shallow shoal and the deep channel, and (2) circulation, owing to the coastline bend of the shallow shoal.

Identifying the origin of strain rate sensitivity in a high entropy bulk metallic glass

A series of nanoindentation tests were performed on a high entropy bulk metallic glass (HE-BMG). At low peak-loads, high positive strain rate sensitivity was found. But increasing the peak-load, the sensitivity of hardness to strain rate decreased dramatically. At low peak-loads, sluggish diffusion in HE-BMG significantly impedes atomic arrangement in the shear yielding events, whereas at high peak-loads, the shear-band deformation is dominated by the shear front triggered events. The work showed the origin of strain rate sensitivity in HE-BMGs and might help for tailoring the mechanical properties.

The analytic study on the heavy steel plate snake rolling with the different roll diameters

The deformation in the inner region along the thickness of the heavy steel plate can be improved by snake rolling method. Then the microstructure and property will be refined and the crack in the inner region may be avoided. So the in-depth research on snake rolling method mechanics parameter modeling should be conducted to guide production. The rolling deformation zone will be divided into back slip zone, cross shear zone, front slip zone and reverse deflection zone according to the direction of the friction during the snake rolling process. The four zones may not exist at the same time. The boundary conditions of existence of the back slip zone, cross shear zone and front slip zone were established by calculating the position of neutral point by a special method. The calculating models which were used to calculate the snake rolling mechanical parameters including the rolling force and rolling torque were setup. The calculated models of unit compressive pressure in the four zones were setup by the slab method, and at this basis, the accurate calculating models of the rolling force and rolling torque were setup according to the composition of the rolling deformation zone and the boundary condition. The mechanical parameters were calculated by the analytic method and the numerical method, and the relative deviation is less than 5% which can satisfy the industrial requirement. The present analytical model can predict the characteristics during snake rolling easily and quickly and it is also suitable for online control applications.

Variation in the Current Shear Front and Its Potential Effect on Sediment Transport Over the Inner Shelf of the East China Sea in Winter

AbstractThe current shear fronts (CSFs) in the East China Sea have been observed during winter in previous studies. In this research, we systematically study characteristics and variation mechanism of the CSFs and its potential effects on the transport of water and suspended sediment and on the inner shelf mud area (ISMA), using the methods of observation data analysis and numerical simulation. The spatial structures, shear intensities, and sea‐land locations of the CSFs are obviously affected by wind, temperature and salinity. The CSFs curve seaward due to the nonuniformity of topography, and the tide causes its periodic and sea‐land shift. The landward U component near the CSFs indicate little cross‐CSF transport (i.e., the barrier effect). The CSFs are important hydrodynamic factors that affect the formation of the ISMA. The periodic shift of the CSFs in the longitudinal direction and its variations in spatial structure are the main mechanisms affecting the spatial distribution and thickness of the ISMA. However, the barrier effect of the CSFs can be interrupted, and both the strong wind in the northeast direction and baroclinic conditions are beneficial for cross‐CSF transport. Furthermore, cross‐CSF transports occur in the upper layers under northwest wind condition, in areas with nonuniformity of topography and during the spring tide period. Three cross‐shelf channels are identified in areas where the CSFs curve seaward resulting from nonuniformity of topography.

Structure of fracture of ice cover, finger rafting

The mechanism of fracture in the vicinity of the region of mutual cutting of ice cover plates is considered on the basis of the analysis of sea ice cover compression structures development. A model of the cutting process based on the representation of this region as the longitudinal shear is proposed. The obtained structures of fracture at shear in the model materials containing capillary pores were analyzed. In particular, it was shown that during the formation of the cracks the distance between cracks along the shear front in the primary echelon structure of brittle fracture is linearly related to the incision tip radius. An estimate is obtained for the effective fracture toughness of ice at longitudinal shear.

On the Holocene evolution of the Ayeyawady megadelta

Abstract. The Ayeyawady delta is the last Asian megadelta whose evolution has remained essentially unexplored so far. Unlike most other deltas across the world, the Ayeyawady has not yet been affected by dam construction, providing a unique view on largely natural deltaic processes benefiting from abundant sediment loads affected by tectonics and monsoon hydroclimate. To alleviate the information gap and provide a baseline for future work, here we provide a first model for the Holocene development of this megadelta based on drill core sediments collected in 2016 and 2017, dated with radiocarbon and optically stimulated luminescence, together with a reevaluation of published maps, charts and scientific literature. Altogether, these data indicate that Ayeyawady is a mud-dominated delta with tidal and wave influences. The sediment-rich Ayeyawady River built meander belt alluvial ridges with avulsive characters. A more advanced coast in the western half of the delta (i.e., the Pathein lobe) was probably favored by the more western location of the early course of the river. Radiogenic isotopic fingerprinting of the sediment suggests that the Pathein lobe coast does not receive significant sediment from neighboring rivers. However, the eastern region of the delta (i.e., Yangon lobe) is offset inland and extends east into the mudflats of the Sittaung estuary. Wave-built beach ridge construction during the late Holocene, similar to several other deltas across the Indian monsoon domain, suggests a common climatic control on monsoonal delta morphodynamics through variability in discharge, changes in wave climate or both. Correlation of the delta morphological and stratigraphic architecture information on land with the shelf bathymetry, as well as its tectonic, sedimentary and hydrodynamic characteristics, provides insight on the peculiar growth style of the Ayeyawady delta. The offset between the western Pathein lobe and the eastern deltaic coast appears to be driven by tectonic–hydrodynamic feedbacks as the extensionally lowered shelf block of the Gulf of Mottama amplifies tidal currents relative to the western part of the shelf. This situation probably activates a perennial shear front between the two regions that acts as a leaky energy fence. Just as importantly, the strong currents in the Gulf of Mottama act as an offshore-directed tidal pump that helps build the deep mid-shelf Mottama clinoform with mixed sediments from the Ayeyawady, Sittaung and Thanlwin rivers. The highly energetic tidal, wind and wave regime of the northern Andaman Sea thus exports most sediment offshore despite the large load of the Ayeyawady River.

Influence of the Longitudinal Shear Crack Tip Radius on the Feathering Structure

The initial phase of feather joint development in the vicinity of a turnpike longitudinal shear vertex is analyzed. Experiments with model materials demonstrate that the crack parameters and the distance between the cracks along the shear front in the primary echelon brittle fracture structure linearly depend on the shear radius. A model for the development of the primary echelon structure along the longitudinal shear front is proposed.