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Liquan Xie
College of Civil Engineering, Tongji University, Shanghai 200092, China

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Technical note
Published: 25 April 2020 in Applied Sciences
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This paper visualizes the onset of scour under a pipeline in regular waves and studies the mechanism in this process. After the test started, the sand particles near the downstream mudline began to oscillate periodically, probably due to the distribution pattern of the seepage hydraulic gradient under the pipeline as well as asymmetric waves. As the wave height gradually increased, the sand under the pipeline began to oscillate at increasing amplitude and the coverage of oscillation extended upstream. Some sand rushed out from the bottom of the pipeline, and the sand oscillated almost symmetrically around the bottom line of the pipeline thereafter. The oscillation amplitude of the sand particles continued to rise, probably due to a decrease in the seepage path under the pipeline and loosened sediment in the oscillation. The scour onset occurred after more sand rushed out from under the pipeline. The visualization results reproduced the delay in the scour onset reported previously, and related the delay to the aforementioned increase in sediment oscillation amplitude. This visualization can improve the understanding of the scour onset mechanism, and can serve as a guide to further investigate the critical conditions of scour onset and scour control countermeasures for offshore structures.

ACS Style

Yehui Zhu; Liquan Xie; Tsun-Ming Wong; Tsung-Chow Su. Visualization of the Onset of Scour under a Pipeline in Waves. Applied Sciences 2020, 10, 2994 .

AMA Style

Yehui Zhu, Liquan Xie, Tsun-Ming Wong, Tsung-Chow Su. Visualization of the Onset of Scour under a Pipeline in Waves. Applied Sciences. 2020; 10 (9):2994.

Chicago/Turabian Style

Yehui Zhu; Liquan Xie; Tsun-Ming Wong; Tsung-Chow Su. 2020. "Visualization of the Onset of Scour under a Pipeline in Waves." Applied Sciences 10, no. 9: 2994.

Journal article
Published: 24 April 2020 in Sustainability
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Underwater pipelines are vital to the oil industry. Extending the service life of these pipelines is a key issue in improving the sustainability of oil transportation. A geotextile mattress with floating plate (GMFP) is a novel and sustainable countermeasure for scour and erosion control and is herein introduced to protect a partially buried pipeline from local scour in steady currents. A series of experiments was designed to verify the protection capabilities of the GMFP and investigate its parametric effects on protection. The average seepage hydraulic gradient under the pipeline was adopted to depict the protection effects of the GMFP, and was calculated with the pore pressure readings under the pipeline. The test results show that the GMFP is capable of protecting a pipeline from the onset of local scour in a unidirectional current. The average seepage hydraulic gradient below the pipeline decreases remarkably after a GMFP is installed. The average hydraulic gradient shows a descending trend with increased sloping angle α when 0.64 < sinα < 0.77. The hydraulic gradient hits a nadir at sinα = 0.77 and climbs with the increasing sloping angle when sinα > 0.82. The hydraulic gradient ascends when the bottom opening ratio δ increases from 0.167 to 0.231, due to the decreased intensity of the bottom vortex. The hydraulic gradient drops with a rising plate height, except for a fluctuation at Hp = 0.12 m. An approximate negative correlation is found between the obstruction height of the floating plate and the average hydraulic gradient under the pipeline. This could be partially attributed to the extension and amplification of the bottom vortex on the leeside of the pipeline due to the increased plate obstruction height.

ACS Style

Yehui Zhu; Liquan Xie; Tsung-Chow Su. Scour Protection Effects of a Geotextile Mattress with Floating Plate on a Pipeline. Sustainability 2020, 12, 3482 .

AMA Style

Yehui Zhu, Liquan Xie, Tsung-Chow Su. Scour Protection Effects of a Geotextile Mattress with Floating Plate on a Pipeline. Sustainability. 2020; 12 (8):3482.

Chicago/Turabian Style

Yehui Zhu; Liquan Xie; Tsung-Chow Su. 2020. "Scour Protection Effects of a Geotextile Mattress with Floating Plate on a Pipeline." Sustainability 12, no. 8: 3482.

Journal article
Published: 21 April 2020 in Water Resources Research
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The vertical distribution pattern of the fine suspended sediment concentration (SSC) plays an important role in the aquatic eco‐system of shallow water. To investigate the SSC profile in submerged vegetated river flow, a series of indoor flume experiments was conducted. Glass spherical balls of three different diameters (40, 77, and 90 μm) with a uniform specific gravity of 2.5 were used for the model sediments. A set of sampling devices was designed for the simultaneous measurements of SSCs at multi‐points along a vertical line. Experimental results show that the SSC profile was re‐distributed in the vegetated region, gradually forming a new equilibrium pattern in the over‐canopy flow layer with its maximum occurring near the canopy top. From this maximum‐point near the canopy top, the suspended sediment formed a dynamic balance between upward turbulent diffusion and downward gravitational settling. Meanwhile, the momentum diffusivity was observed to linearly decrease upward from the maximum‐SSC elevation towards the water surface, thereby allowing us to deduce an empirical negative linear formula. Based on the convection‐diffusion equilibrium mechanism and with assistance of the empirical formula of flow momentum diffusivity, a new form of the Rouse formula was derived for the over‐canopy flow layer. In general, this equation agrees well with the measured data. Some under‐calculated deviations appear in the well‐above canopy zone due to the up‐skewed turbulence and the weak upward secondary flow. This deviation decreases with increasing sediment diameter. The bed‐deposition mainly comes from the deep part of canopy‐occupied flow layer.

ACS Style

Y. Li; L. Xie; T. C. Su. Profile of Suspended Sediment Concentration in Submerged Vegetated Shallow Water Flow. Water Resources Research 2020, 56, 1 .

AMA Style

Y. Li, L. Xie, T. C. Su. Profile of Suspended Sediment Concentration in Submerged Vegetated Shallow Water Flow. Water Resources Research. 2020; 56 (4):1.

Chicago/Turabian Style

Y. Li; L. Xie; T. C. Su. 2020. "Profile of Suspended Sediment Concentration in Submerged Vegetated Shallow Water Flow." Water Resources Research 56, no. 4: 1.

Conference paper
Published: 31 March 2020 in IOP Conference Series: Materials Science and Engineering
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Suction foundation, as a new type of marine anchoring foundation, has the advantages of reuse, fast construction, and large vertical bearing capacity. In this paper, through a self-developed bearing capacity test device, a series of load-bearing performance tests of the suction foundation are performed to reproduce the bearing characteristics of the suction foundation under the action of the pull-up load. It can be found that bearing capacity of suction foundation increases with the penetration, and the influence of the inclination angle on the bearing capacity of the suction foundation is in a middle value range.

ACS Style

Yiren Huang; Shili Ma; Liquan Xie; Wencai Huang. Experiments on loading capability of Inclined Suction Foundation. IOP Conference Series: Materials Science and Engineering 2020, 768, 1 .

AMA Style

Yiren Huang, Shili Ma, Liquan Xie, Wencai Huang. Experiments on loading capability of Inclined Suction Foundation. IOP Conference Series: Materials Science and Engineering. 2020; 768 ():1.

Chicago/Turabian Style

Yiren Huang; Shili Ma; Liquan Xie; Wencai Huang. 2020. "Experiments on loading capability of Inclined Suction Foundation." IOP Conference Series: Materials Science and Engineering 768, no. : 1.

Journal article
Published: 13 January 2020 in Applied Sciences
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The rapid development of offshore wind energy in China is becoming increasingly relevant for movement toward green development. This paper presents the results of visual tests of a suction caisson used as foundation for offshore wind turbines. The distribution of hydraulic gradients of sand at the mudline in the caisson was obtained to find out the relationship with the heights of soil plugs. The relationship equation was proposed and obtained by using quadratic regression, guiding project designs, and construction. It was found that there was no soil plug in the caisson when small suction was applied during the suction penetration. The relationship between the heights of the soil plugs and the hydraulic gradient of the soil was proposed and obtained by using quadratic regression to predict (roughly) the height of soil plugs in suction caissons in sand during suction penetration. The influence of settlement outside caissons on the soil plug was found to decrease as the buried depth rose.

ACS Style

Liquan Xie; Shili Ma; Tiantian Lin. The Seepage and Soil Plug Formation in Suction Caissons in Sand Using Visual Tests. Applied Sciences 2020, 10, 566 .

AMA Style

Liquan Xie, Shili Ma, Tiantian Lin. The Seepage and Soil Plug Formation in Suction Caissons in Sand Using Visual Tests. Applied Sciences. 2020; 10 (2):566.

Chicago/Turabian Style

Liquan Xie; Shili Ma; Tiantian Lin. 2020. "The Seepage and Soil Plug Formation in Suction Caissons in Sand Using Visual Tests." Applied Sciences 10, no. 2: 566.

Technical note
Published: 04 January 2020 in Water
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Rigid flow deflectors are usually used on water flow beds to protect engineering structures such as breakwater in coasts and to regulate flow routes in open channels. To reduce its side-effects, i.e., local scour at the toe of deflectors, a flexible flow deflector is proposed, and the corresponding local scour was investigated in this study. A flume experiment was conducted to investigate local scour. To show the advantage of flexible deflectors, a control experimental test was also conducted using a traditional rigid deflector under the same blockage area configuration and the same flow conditions. The flow field near the flexible deflector was also measured to reveal the local flow field. The results show that the bed-scour develops near the toe edges of both flexible and rigid deflectors, but the maximum and averaged scour depths for the flexible deflector are smaller. This advantage of flexible deflector in scour depth is mainly caused by its prone posture, which induces the upward stretching and enlarging horizontally rotating vortex and the upward shifted vertically rotating vortex. The former dissipates more turbulent energy and the latter results in smaller bed shear stress, which lead to smaller scour depth directly. In addition, the up- and down-swaying movement of the flexible deflector can also assistant to dissipate more turbulent energy, thereby damping the intense of the horseshoe vortices and thus weakening scour depth as well. The results of this study provide an elementary understanding on the mechanisms of a flexible flow structure and an alternative deflector-device to reduce scour depth.

ACS Style

Liquan Xie; Yehui Zhu; Huang Li; Yan-Hong Li; Yuanping Yang; Tsung-Chow Su. Local Scour Near Flexible Flow Deflectors. Water 2020, 12, 153 .

AMA Style

Liquan Xie, Yehui Zhu, Huang Li, Yan-Hong Li, Yuanping Yang, Tsung-Chow Su. Local Scour Near Flexible Flow Deflectors. Water. 2020; 12 (1):153.

Chicago/Turabian Style

Liquan Xie; Yehui Zhu; Huang Li; Yan-Hong Li; Yuanping Yang; Tsung-Chow Su. 2020. "Local Scour Near Flexible Flow Deflectors." Water 12, no. 1: 153.

Article
Published: 21 December 2019 in Computational Particle Mechanics
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In this paper, uniaxial compression tests on layered rock specimens are numerically modelled using the discrete element method to investigate the effect of a soft interlayer on the strength and deformation of rock specimens. For these simulations, the thickness and dip angle of the soft interlayer were varied. Thirty-five numerical models for different cases were established after calibrating the micro-mechanical parameters of the hard and soft rock materials. The computational results were analysed in terms of three aspects: the stress–strain curves, micro-crack propagation patterns, and particle velocity fields. The stress–strain curves indicate that increasing the thickness and dip angle of the soft interlayer causes the peak stress and ultimate strain to drop by up to 42% and 34%, respectively. The thickness of the soft interlayer has a greater influence than that of the soft interlayer dip angle on the uniaxial mechanical behaviour of the rock specimen. Additionally, crack propagation patterns and particle motion in the layered rock models indicate that the cracks develop preferentially along the soft interlayer and that the notable failure features of the layered rock models are stepped failure modes that occur at greater dip angles.

ACS Style

Liquan Xie; Peng Jin; Tsung-Chow Su; Xiaobo Li; Zelong Liang. Numerical simulation of uniaxial compression tests on layered rock specimens using the discrete element method. Computational Particle Mechanics 2019, 7, 753 -762.

AMA Style

Liquan Xie, Peng Jin, Tsung-Chow Su, Xiaobo Li, Zelong Liang. Numerical simulation of uniaxial compression tests on layered rock specimens using the discrete element method. Computational Particle Mechanics. 2019; 7 (4):753-762.

Chicago/Turabian Style

Liquan Xie; Peng Jin; Tsung-Chow Su; Xiaobo Li; Zelong Liang. 2019. "Numerical simulation of uniaxial compression tests on layered rock specimens using the discrete element method." Computational Particle Mechanics 7, no. 4: 753-762.

Journal article
Published: 19 December 2019 in Water
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Plants in natural water flow can improve water quality by adhering and absorbing the fine suspended sediments. Dense plants usually form an additional permeable bottom boundary for the water flow over it. In the flow layer above dense plants, the flow velocity generally presents a zero-plane-displacement and roughness-height double modified semi-logarithmic profile. In addition, the second order shear turbulent moment (or the Reynolds stress) are different from that found in non-vegetated flow. As a result, the turbulent momentum diffusivity of flow and thus the diffusivity of sediment will shift, which will cause the vertical profile of suspended sediment and the corresponding Rouse formula deform. A set of physical experiments with three different diameters of fine suspended sediments was conducted in an indoor water flume. These experiments investigated a new distribution pattern of suspended sediment and the correspondingly deformed Rouse formula in the flow layer over the dense plants. Experimental results showed that above the dense plants, the shear turbulent momentum of flow presented a plant-height modified negative linear profile, which has been proposed by a previous study, and the vertical distribution of fine suspended sediments presented an equilibrium pattern. Based on the plant-modified profiles of flow velocity and the shear turbulent momentum a new zero-plane and plant-height double modified Rouse formula were analytically derived. This double-parameter modified Rouse formula agrees well with the measured profile of suspended sediment concentration experimentally observed in the present study. By adjusting the Prandtl–Schmidt number, i.e., the ratio of sediment diffusivity to flow diffusivity, the double-parameter modified Rouse formula can be applied to submerged dense plant occupied flow.

ACS Style

Yanhong Li; Liquan Xie; Tsung-Chow Su. Vertical Distribution of Suspended Sediments above Dense Plants in Water Flow. Water 2019, 12, 12 .

AMA Style

Yanhong Li, Liquan Xie, Tsung-Chow Su. Vertical Distribution of Suspended Sediments above Dense Plants in Water Flow. Water. 2019; 12 (1):12.

Chicago/Turabian Style

Yanhong Li; Liquan Xie; Tsung-Chow Su. 2019. "Vertical Distribution of Suspended Sediments above Dense Plants in Water Flow." Water 12, no. 1: 12.

Journal article
Published: 02 December 2019 in International Journal of Environmental Research and Public Health
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Vegetation has already been acknowledged to have the ability to remove fine solid pollutants by retention and absorption, and is widely used in the biorestoration engineering of natural shallow water flow. Vegetation usually takes a long time to obtain the expected removal rate. Therefore, vegetation is not applicable for some urgent or pressing situations. In addition, in traditional biorestoration engineering, solid pollutants usually deposit in the soil of flow bed, which infiltrates into the far-field and accumulates in crops to threaten human health. Herein, we propose a new biotechnique of foliage capture by designing a cave on the top of a vegetation canopy, which is aimed to enhance the removal efficiency (i.e., achieve quick removal) and avoid the soil deposition of pollutants. The effectiveness and efficiency of this new design were validated by a set of indoor water flume experiments, with one flat canopy top configuration serving as the model of a traditional bioretention system and three cave configurations of differing aspect ratios. The results showed that compared with that of the flat canopy top, the total amount of foliage-captured solid particles for the three caved canopies increased by 3.8, 7.3, and 12.2 times. Further, we found that the foliage-capture efficiency depended on the aspect ratio of the canopy cave. The results revealed that the effectiveness of foliage capture and the enhanced efficiency were mainly from three hydrodynamic mechanisms: (i) as flow penetrated the cave boundary from the above-canopy region to the within-canopy region, it entrained solid pollutants to collide with the foliage and increased their fate of capture; (ii) the large eddy vortices of turbulence broke due to the increasing canopy resistance, which resulted in enhanced mixing dynamics for fine, suspended, solid pollutants to collide into foliage; and (iii) the flow shear along the cave boundary decreased, which provided a reduced lift force for solid pollutants to suspend or resuspend. Comparisons between the flat canopy and caved canopies of three aspect ratios showed that the design of the canopy cave is highly significant for capture efficiency.

ACS Style

Yanhong Li; Liquan Xie; Tsung-Chow Su. Bio-Capture of Solid Pollutants by Vegetation Canopy Cave in Shallow Water Flow. International Journal of Environmental Research and Public Health 2019, 16, 4846 .

AMA Style

Yanhong Li, Liquan Xie, Tsung-Chow Su. Bio-Capture of Solid Pollutants by Vegetation Canopy Cave in Shallow Water Flow. International Journal of Environmental Research and Public Health. 2019; 16 (23):4846.

Chicago/Turabian Style

Yanhong Li; Liquan Xie; Tsung-Chow Su. 2019. "Bio-Capture of Solid Pollutants by Vegetation Canopy Cave in Shallow Water Flow." International Journal of Environmental Research and Public Health 16, no. 23: 4846.

Journal article
Published: 01 October 2019 in Journal of Marine Science and Engineering
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The intersection of the span shoulder and the scour hole under a pipeline, also called the scour front, can affect the scour hole extension rate and the bearing capacity of the span shoulder, which is associated with pipeline spanning and failure. Studies on scour front evolution are limited due to technical restrictions. In this study, visualization experiments on three-dimensional scour under a pipeline in steady currents were performed to reveal the evolution of the scour front at the beginning of scour process, and the parametric effects on the scour front pattern. The angle of scour front witnessed a steady drop at the start of the scour development process and fluctuated gently thereafter. This can be attributed to the decrease in the blockage effect over time. A gravitational movement was observed on the downstream end of the scour front, which is associated with the variation of fluid pressure along the scour front. The scour front pattern was described by the angle between the scour front and the streamwise direction. Parametric analysis showed that the averaged scour front angle climbs as the Froude number increases and the pipeline embedment drops. This phenomenon can be expounded by the intensified flow deflection near the span shoulder due to the enhancement of the pipeline blockage effect, caused by the ascending Froude number and descending pipeline embedment. The results of this study can be adopted in future mechanism investigations on the scour hole propagation rate and the failure analysis on the span shoulder.

ACS Style

Liquan Xie; Yehui Zhu; Tsung-Chow Su. Visualization Tests on Variation of Scour Front under a Pipeline in Steady Currents. Journal of Marine Science and Engineering 2019, 7, 345 .

AMA Style

Liquan Xie, Yehui Zhu, Tsung-Chow Su. Visualization Tests on Variation of Scour Front under a Pipeline in Steady Currents. Journal of Marine Science and Engineering. 2019; 7 (10):345.

Chicago/Turabian Style

Liquan Xie; Yehui Zhu; Tsung-Chow Su. 2019. "Visualization Tests on Variation of Scour Front under a Pipeline in Steady Currents." Journal of Marine Science and Engineering 7, no. 10: 345.

Conference paper
Published: 18 September 2019 in IOP Conference Series: Earth and Environmental Science
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To study the mechanism of bearing capacity of a suction bucket, a series of centrifugal tests were designed to investigate the uplift bearing capacity, and the entire dynamic process of pore water pressure were monitored as well. The results show that with the increase of inclined degree of suction foundation, the bearing capacity of suction foundation decreases continuously, and the influence of inclination on the foundation bearing capacity is obvious.

ACS Style

Liquan Xie; Yifan Ji. The centrifuge experiments on influence of inclination on bearing capacity of the suction bucket. IOP Conference Series: Earth and Environmental Science 2019, 304, 022083 .

AMA Style

Liquan Xie, Yifan Ji. The centrifuge experiments on influence of inclination on bearing capacity of the suction bucket. IOP Conference Series: Earth and Environmental Science. 2019; 304 (2):022083.

Chicago/Turabian Style

Liquan Xie; Yifan Ji. 2019. "The centrifuge experiments on influence of inclination on bearing capacity of the suction bucket." IOP Conference Series: Earth and Environmental Science 304, no. 2: 022083.

Journal article
Published: 24 June 2019 in Powder Technology
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Utilizing deployable morphing structures in ocean engineering applications is a practice in its infancy. We propose an inflatable tubular beam using a hydrogel bead's ability to absorb water to achieve the desired structural shape and strength. It is therefore essential to know the strength of the morphed structure. The first step is to study the strength of the simple structural element. This paper focuses on the numerical modelling of bending tests on inflatable tubular structures filled with hydrogel beads to elucidate the various deformations of multiple compositions of bead/tube structures using the discrete element method. The properties of the tubes and beads were obtained, then calibrations of the micro numerical parameters were conducted. Twenty-four cases of bending tests were simulated. The results show that the degree to which the beads are filled, along with the bead's radius, have a direct effect on the composite structure's strength against deformation.

ACS Style

Liquan Xie; Peng Jin; Huishu Li; Xin Liang; Tsung-Chow Su. Numerical investigation of inflatable structures filled with hydrogel beads. Powder Technology 2019, 354, 689 -695.

AMA Style

Liquan Xie, Peng Jin, Huishu Li, Xin Liang, Tsung-Chow Su. Numerical investigation of inflatable structures filled with hydrogel beads. Powder Technology. 2019; 354 ():689-695.

Chicago/Turabian Style

Liquan Xie; Peng Jin; Huishu Li; Xin Liang; Tsung-Chow Su. 2019. "Numerical investigation of inflatable structures filled with hydrogel beads." Powder Technology 354, no. : 689-695.

Journal article
Published: 01 April 2019 in Journal of Hydraulic Engineering
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ACS Style

Yehui Zhu; Liquan Xie; Tsung-Chow Su. Visualization Tests on Scour Rates below Pipelines in Steady Currents. Journal of Hydraulic Engineering 2019, 145, 04019005 .

AMA Style

Yehui Zhu, Liquan Xie, Tsung-Chow Su. Visualization Tests on Scour Rates below Pipelines in Steady Currents. Journal of Hydraulic Engineering. 2019; 145 (4):04019005.

Chicago/Turabian Style

Yehui Zhu; Liquan Xie; Tsung-Chow Su. 2019. "Visualization Tests on Scour Rates below Pipelines in Steady Currents." Journal of Hydraulic Engineering 145, no. 4: 04019005.

Journal article
Published: 01 March 2019 in Journal of Hydraulic Engineering
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A geotextile mattress with sloping curtain (GMSC) was introduced to protect underwater pipelines from scour in steady currents. GMSC is a newly developed countermeasure against river and estuarine scour. To better understand the beneficial effects of GMSC on seepage flow under pipelines, dye was injected to determine the hydraulic gradients across the pipeline in a series of verification tests. Hydraulic gradients across the pipeline with and without a GMSC were quantified for different curtain angles, curtain heights of the GMSC, and distances between the pipeline and the GMSC, and installing GMSCs with or without sand-pass openings, which are openings to allow bottom flow with a high concentration of sediment to pass. The results of the experiments show that a GMSC is capable of protecting a pipeline against scour in a steady current by effectively reducing the hydraulic gradient in the bed soil below the pipeline. The hydraulic gradient across the pipeline decreases nonlinearly with the increase of curtain height and angle of the GMSC. The effect of sand-pass openings on the hydraulic gradient across the pipeline is not significant. The hydraulic gradient decreases nonlinearly with decreasing distance between the pipeline and the GMSC. When the distance decreases below a critical point, the seepage flow under the pipeline reverses. The GMSC may provide an optimum protection effect on the pipeline when the distance between the pipeline and the GMSC is about 6 times the obstacle height of the GMSC (Hcsinα) by reducing the flow velocity approaching the pipeline close to zero.

ACS Style

Liquan Xie; Yehui Zhu; Tsung-Chow Su. Scour Protection of Partially Embedded Pipelines Using Sloping Curtains. Journal of Hydraulic Engineering 2019, 145, 04019001 .

AMA Style

Liquan Xie, Yehui Zhu, Tsung-Chow Su. Scour Protection of Partially Embedded Pipelines Using Sloping Curtains. Journal of Hydraulic Engineering. 2019; 145 (3):04019001.

Chicago/Turabian Style

Liquan Xie; Yehui Zhu; Tsung-Chow Su. 2019. "Scour Protection of Partially Embedded Pipelines Using Sloping Curtains." Journal of Hydraulic Engineering 145, no. 3: 04019001.

Research article
Published: 25 January 2019 in PLOS ONE
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A geotextile mattress with sloping curtain is a newly proposed countermeasure against river and estuarine scour. In previous laboratory experiments, a geotextile mattress with sloping curtain was capable of protecting the bed downstream from scour and stimulating sediment deposition on both sides. However, the seepage scour under its geotextile mattress is inadequately researched at present. In this study, the Geotextile Mattress with Sloping Plate (GMSP) is proposed based on the simplification of the geotextile mattress with sloping curtain with the construction feasibility considered. A series of experiments was conducted to investigate the pressure distribution around the GMSP and the averaged seepage hydraulic gradient beneath its mattress. The results indicate remarkable pressure difference on two sides of the GMSP. The minimum bed pressure appears about 1.3 times the plate height downstream to the GMSP. The averaged seepage hydraulic gradient beneath the mattress increases with the sloping angle increasing from 35° to 60° in general. The averaged hydraulic gradient also ascends as the relative plate height increases, but reduces as the opening ratio increases at opening ratios greater than 0.143. The safety boundary for the averaged hydraulic gradient under the geotextile mattress of the GMSP could get much smaller than the critical hydraulic gradient of piping and can easily be overwhelmed. This phenomenon can mainly be attributed to the discontinuous contact between the mattress and the seabed. A suggestion for the parametric design of the GMSP is to extend the width of the mattress to reduce the risk of seepage failure.

ACS Style

Liquan Xie; Yehui Zhu; Yanhong Li; Tsung-Chow Su. Experimental study on bed pressure around geotextile mattress with sloping plate. PLOS ONE 2019, 14, e0211312 .

AMA Style

Liquan Xie, Yehui Zhu, Yanhong Li, Tsung-Chow Su. Experimental study on bed pressure around geotextile mattress with sloping plate. PLOS ONE. 2019; 14 (1):e0211312.

Chicago/Turabian Style

Liquan Xie; Yehui Zhu; Yanhong Li; Tsung-Chow Su. 2019. "Experimental study on bed pressure around geotextile mattress with sloping plate." PLOS ONE 14, no. 1: e0211312.

Conference paper
Published: 11 October 2018 in IOP Conference Series: Earth and Environmental Science
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The submerged vegetation patch in river flow produces additional resistance through drag force and changes the bed shear stress of flow. Thereby it influences the deposition of fine particles including some kind of metal pollutants on flow bed. The relative height of vegetation patch imposes influence on the variation of bed shear stress, therefore it being expected to influence the deposition of fine particles as well. To investigate the influence of relative height of vegetation patch on deposition of fine particles in river flow, a set of indoor physical experiments with twelve relative heights were conducted in a straight water flume. The results show that for low relative heights, the deposition decreases with the increase of relative height. For medium relative heights, the deposition increases with the increase of relative height. For high relative heights, the deposition no longer varies with the increase of relative height. There are two main contrary effects accounting for this variation, the first one is the increased flow velocity due to the compassed cross-sectional area, which cause the bed shear stress increasing. The second effect is from the increasing drag force with the increasing submergence of vegetation patch, which causes the bed shear decreasing. The results of this study are expected to provide fundamental mechanisms for the removal of metal pollutant through vegetation patch in river flow.

ACS Style

Yan-Hong Li; Liquan Xie. Deposition of fine particles in submerged vegetation patch in river flow. IOP Conference Series: Earth and Environmental Science 2018, 186, 012032 .

AMA Style

Yan-Hong Li, Liquan Xie. Deposition of fine particles in submerged vegetation patch in river flow. IOP Conference Series: Earth and Environmental Science. 2018; 186 (3):012032.

Chicago/Turabian Style

Yan-Hong Li; Liquan Xie. 2018. "Deposition of fine particles in submerged vegetation patch in river flow." IOP Conference Series: Earth and Environmental Science 186, no. 3: 012032.

Journal article
Published: 01 October 2018 in Canadian Geotechnical Journal
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The hole erosion test (HET) is commonly used to study the occurrence of internal soil erosion when water concentrated leaks occur. This erosion is known as “piping” in soil mechanics. Piping erosion is invisible and occurs randomly within the soil body. Therefore, to gain a better understanding of how piping erosion develops, it would be helpful to utilize a viewable HET design in which the dynamics of the piping hole can be observed directly. In this note, a new HET apparatus is presented that can be used to observe the development of piping erosion and to monitor the dynamic pressure condition during the hole erosion process. A preliminary model test was carried out based on the new viewable HET apparatus and “pressure heads” monitoring technique. The results successfully verified the performance of the proposed apparatus and experimental methods during the process of hole erosion, indicating that the hole shape changes during continuous erosion and is not fully symmetrical because of the initial profile of the hole. The internal hole becomes increasingly curved when subjected to continuous piping flow. Test results agree with the numerical simulation reported in 2015 by Riha and Jandora, who considered the effect of the hole entrance shape.

ACS Style

Liquan Xie; Xin Liang; Tsung-Chow Su. Measurement of pressure in viewable hole erosion test. Canadian Geotechnical Journal 2018, 55, 1502 -1509.

AMA Style

Liquan Xie, Xin Liang, Tsung-Chow Su. Measurement of pressure in viewable hole erosion test. Canadian Geotechnical Journal. 2018; 55 (10):1502-1509.

Chicago/Turabian Style

Liquan Xie; Xin Liang; Tsung-Chow Su. 2018. "Measurement of pressure in viewable hole erosion test." Canadian Geotechnical Journal 55, no. 10: 1502-1509.

Journal article
Published: 01 March 2018 in Journal of Hydraulic Engineering
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The resistance of an open-channel flow under the influence of bending deformation of submerged flexible vegetation canopy was experimentally studied in an indoor water flume. Altogether, 27 tests under the cross-combinations of three bulk flow velocities (V), three vegetation elastic moduli (E), and three vegetation stem thicknesses (b) were conducted. The total drag force experienced by the vegetation stem was accurately calculated based on the measured vertical profiles of flow velocity and the second order turbulent momentum in front of an individual plant, and this enabled the estimation of the overall drag coefficient (CD) for bulk flow. The results show that the bending deformation of vegetation helps to transfer momentum downward toward the channel bed, thus helping to reduce the overall resistance to flow. The Cauchy number (CY) is an important parameter representing the bending property of the vegetation in open-channel flow; it’s functionally related to the resistance of flow. For small deformation configurations, the bending angle (θ) and the relative bending displacement (δz/hp) are linearly dependent on CY and (CY)2, respectively. The CD and Manning’s n for the bulk flow are both power law functions of CY. The semiempirical formulas of CD and n proposed in this study are expected to apply to further experimental studies and river engineering.

ACS Style

Yan-Hong Li; Liquan Xie; Tsung-Chow Su. Resistance of Open-Channel Flow under the Effect of Bending Deformation of Submerged Flexible Vegetation. Journal of Hydraulic Engineering 2018, 144, 04017072 .

AMA Style

Yan-Hong Li, Liquan Xie, Tsung-Chow Su. Resistance of Open-Channel Flow under the Effect of Bending Deformation of Submerged Flexible Vegetation. Journal of Hydraulic Engineering. 2018; 144 (3):04017072.

Chicago/Turabian Style

Yan-Hong Li; Liquan Xie; Tsung-Chow Su. 2018. "Resistance of Open-Channel Flow under the Effect of Bending Deformation of Submerged Flexible Vegetation." Journal of Hydraulic Engineering 144, no. 3: 04017072.

Website
Published: 06 December 2017 in Hydraulic Engineering V
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Binglian Hu; Liquan Xie; Tsung-Chow Su. Numerical simulations of flow past a submerged vertical cylinder with porous structure. Hydraulic Engineering V 2017, 229 -234.

AMA Style

Binglian Hu, Liquan Xie, Tsung-Chow Su. Numerical simulations of flow past a submerged vertical cylinder with porous structure. Hydraulic Engineering V. 2017; ():229-234.

Chicago/Turabian Style

Binglian Hu; Liquan Xie; Tsung-Chow Su. 2017. "Numerical simulations of flow past a submerged vertical cylinder with porous structure." Hydraulic Engineering V , no. : 229-234.

Journal article
Published: 18 September 2017 in DEStech Transactions on Environment, Energy and Earth Sciences
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A series of indoor experiment were carried out to investigate the optimal placement of a new type of wave energy converter, the tilt-ladder-breakwater (TLB). The TLB is a Chinese patented device that transforms the wave energy into current energy to create electricity. The main part of this device is a breakwater with its wave-ward front-wall composing of tilt ladders. The tilt ladders are used to beak waves and guide the current into their low end to provide concentrated energy for the generation of electric power. This device is simple and low-cost in construction and high efficient in power-generation. It has great application prosperity in coastal areas. For the purpose of obtaining an optimal orientation of TLB, a series of experimental tests were carried out. The concentrated current forces (

ACS Style

Yanhong Li; Liquan Xie; Tsung-Chow Su. Optimal Placement of a New Wave Energy Converter–Tilt-Ladder-Breakwater. DEStech Transactions on Environment, Energy and Earth Sciences 2017, 1 .

AMA Style

Yanhong Li, Liquan Xie, Tsung-Chow Su. Optimal Placement of a New Wave Energy Converter–Tilt-Ladder-Breakwater. DEStech Transactions on Environment, Energy and Earth Sciences. 2017; (icnerr):1.

Chicago/Turabian Style

Yanhong Li; Liquan Xie; Tsung-Chow Su. 2017. "Optimal Placement of a New Wave Energy Converter–Tilt-Ladder-Breakwater." DEStech Transactions on Environment, Energy and Earth Sciences , no. icnerr: 1.