scholarly journals Numerical Investigating on Representativeness of Tracers in PIV Model Test of Dredged Slurry Treated by Vacuum Preloading

2021 ◽  
Vol 11 (20) ◽  
pp. 9715
Author(s):  
Jiahao Wang ◽  
Zunan Fu ◽  
Yanming Yu ◽  
Guoshuai Wang ◽  
Li Shi ◽  
...  
Keyword(s):  
Soil Column ◽  
Carbon Powder ◽  
Vacuum Preloading ◽  
Particle Image Velocimetry Technique ◽  
Consolidation Process ◽  
Railway Line ◽  
Image Velocimetry ◽  
Prefabricated Vertical Drain ◽  
The Difference ◽  
Cfd Method

The vacuum preloading method is commonly adopted for improving the soft ground that the embankment of the railway line is laid on. The PIV (Particle Image Velocimetry) technique is a powerful tool in observing the formation of the soil column, a phenomenon that is unique to the dredged slurry when treated by vacuum preloading. However, it is not clear to what extent the motions of the slurry particles can be represented by the PIV tracers. In this paper, a mesoscopic model has been established by using the CFD-DEM method to reproduce the vacuum consolidation process of the slurry, in which the PVD (Prefabricated Vertical Drain) membrane, the slurry particles, and the tracers are described by the DEM, and the pore water is governed by the CFD method. Eight computational cases that can cover a broad range of material parameters governing the PIV model tests on the dredged slurry have been designed and studied by the established model. The representativeness of the PIV tracer is evaluated by comparing the statistic displacement of the tracer to that of the slurry particles. It is found that for the commonly used tracer, the carbon powder, can reliably represent the particle motions of the slurry since the difference in displacements of the tracer and the slurry particles is smaller than 6.5% if the diameter ratio between the tracer and the slurry particle is within 1.8.

scholarly journals ANALISIS PENGARUH METODE PERBAIKAN TANAH VACUUM PRELOADING TERHADAP STRUKTUR ABUTMENT DI SEKITARNYA

2021 ◽  
Vol 4 (3) ◽  
pp. 641
Author(s):  
Steven Djunawan ◽  
Andryan Suhendra
Keyword(s):  
Soft Soil ◽  
Soil Layer ◽  
Infrastructure Development ◽  
Lateral Movement ◽  
Vacuum Preloading ◽  
Consolidation Process ◽  
Distance Analysis ◽  
Vertical Drain ◽  
Prefabricated Vertical Drain ◽  
Long Time

Soft soil in Indonesia is problematic in infrastructure development because of its low bearing capacity and takes a long time to consolidate. In general, the method used to overcome soft soil is vacuum preloading combined with prefabricated vertical drain, PVD. The purpose of the initial loading is to consolidate the soft soil layer with a load equal to or greater than the soil load during and after construction. Meanwhile, vertical can support the consolidation process. However, this method can also cause lateral movement which also affects the area outside the repair. Thus, it is necessary to model the influence distance analysis from the circumference of the repair area outside the repair. Analysis and modeling using 2D finite program elements that will be compared with results in field. The results of the comparison of the settlement for 260 days shows a different chart pattern but a corresponding final settlement. The modeling shows that the largest influence distance due to the lateral movement is cell 2, which is 11,23mTanah lunak di Indonesia menjadi problematika pada pembangunan infrastruktur dikarenakan daya dukung yang rendah serta memakan waktu penurunan konsolidasi yang lama. Pada umumnya, perbaikan tanah yang digunakan untuk mengatasi tanah lunak adalah vacuum preloading yang dikombinasikan dengan prefabricated vertical drain, PVD. Tujuan pembebanan awal adalah untuk mengkonsolidasikan lapisan tanah lunak dengan beban sama atau lebih besar dari beban tanah selama dan setelah konstruksi. Sementara drainase vertikal dapat mempercepat proses konsolidasi. Namun, metode ini juga dapat penyebabkan pergerakan lateral yang juga mempengaruhi area diluar perbaikan. Sehingga, dibutuhkan pemodelan analisis jarak pengaruh dari keliling daerah perbaikan ke daerah luar perbaikan. Analisis dan pemodelan menggunakan program elemen hingga 2D yang akan dibandingkan dengan hasil lapangan. Hasil perbandingan penurunan selama 260 hari menunjukan pola grafik yang berbeda namun penurunan akhir yang sesuai. Pemodelan menunjukan jarak pengaruh terbesar akibat pergerakan lateral berada pada cell 2 yaitu 11,23m.

scholarly journals Analisis Alternatif Perbaikan Tanah Lunak dan Sangat Lunak pada Jalan Tol

2020 ◽  
Vol 3 (4) ◽  
pp. 1137
Author(s):  
Christian Eka Putra ◽  
Chaidir Anwar Makarim
Keyword(s):  
Bearing Capacity ◽  
Soft Soil ◽  
Soft Clay ◽  
Soil Improvement ◽  
High Water Content ◽  
Vacuum Preloading ◽  
Consolidation Process ◽  
Toll Road ◽  
Vertical Drain ◽  
Prefabricated Vertical Drain

The existence of soft soil is one of the problems in the field of construction. Soft soil is soil that has high water content and low carrying capacity. In the case of this toll road, soil investigation at the site shows that the subgrade in the toll road planning is soft clay soil to a depth of 32 meters so that soil improvement is needed. High landfill built on soft subgrade without reinforcement will experience landslides. So it is necessary to strengthen the landfill and repair the subgrade to prevent road slides. The soil improvement methods in use are vacuum preloading and Prefabricated Vertical Drain with the vacuum functioning as an additional load. In addition to accelerating the consolidation process, the vacuum can also reduce the height of the embankment needed to achieve the desired planned road elevation. Strengthening with geotextile is also carried out on the landfill with a height of 5.94 meters so that there is no landslide on the fill. Using soil improvement methods such as vacuum preloading and prefabricated vertical drain will increase the bearing capacity of the soil so that differences in bearing capacity occur before and after repair. AbstrakKeberadaan tanah lunak menjadi salah satu masalah dalam bidang konstruksi. Tanah lunak adalah tanah yang memiliki kadar air yang tinggi dan daya dukung yang rendah. Pada kasus jalan tol ini, penyelidikan tanah di lokasi menunjukan bahwa tanah dasar pada perencanaan jalan tol merupakan tanah lempung lunak hingga kedalaman 32 meter sehingga dibutuhkan perbaikan tanah dasar. Timbunan tinggi yang dibangun di atas tanah dasar lunak tanpa perkuatan akan mengalami kelongsoran. Sehingga diperlukan perkuatan timbunan dan perbaikan tanah dasar untuk mencegah kelongsoran jalan. Metode perbaikan tanah yang digunakan adalah vacuum preloading dan Prefabricated Vertical Drain dengan vacuum berfungsi sebagai beban tambahan. Selain mempercepat proses penurunan, vacuum juga dapat mengurangi tinggi timbunan yang dibutuhkan untuk mencapai elevasi jalan rencana yang diinginkan. Perkuatan dengan geotextile juga dilakukan pada timbunan dengan tinggi yang mencapai 5.94 meter supaya tidak terjadi kelongsoran pada timbunan tersebut. Dengan menggunakan metode perbaikan tanah berupa vacuum preloading dan prefabricated vertical drain akan meningkatkan daya dukung tanah sehingga akan diketahui perbedaan daya dukung yang terjadi sebelum dan sesudah diperbaiki.

scholarly journals Numerical Investigation to the Effect of Suction-Induced Seepage on the Settlement in the Underwater Vacuum Preloading with Prefabricated Vertical Drains

2021 ◽  
Vol 9 (8) ◽  
pp. 797
Author(s):  
Shu Lin ◽  
Dengfeng Fu ◽  
Zefeng Zhou ◽  
Yue Yan ◽  
Shuwang Yan
Keyword(s):  
Practical Implication ◽  
Soil Surface ◽  
Small Strain ◽  
Seepage Flow ◽  
Excess Pore Pressure ◽  
Combined Effects ◽  
Vacuum Preloading ◽  
Prefabricated Vertical Drains ◽  
Vertical Drains ◽  
The Difference

Vacuum preloading combined with prefabricated vertical drains (PVDs) has the potential to improve the soft sediments under water, however, its development is partly limited by the unclear understanding of the mechanism. This paper aims to extend the comprehension of the influential mechanism of overlapping water in the scenario of underwater vacuum preloading with PVDs. The systematic investigations were conducted by small strain finite element drained analyses, with the separated analysis schemes considering suction-induced consolidation, seepage and their combination. The development of settlement in the improved soil region and the evolution of seepage flow from the overlapping water through the non-improved soil region into improved zone are examined in terms of the build-up of excess pore pressure. Based on the results of numerical analyses, a theoretical approach was set out. It was capable to estimate the time-dependent non-uniform settlement along the improved soil surface in response to the combined effects of suction-induced consolidation and seepage. The difference of underwater and onshore vacuum preloading with PVDs is discussed with some practical implication and suggestion provided.

Analysis of local velocity gradients in rapid mixer using particle image velocimetry technique

2002 ◽  
Vol 2 (5-6) ◽  
pp. 47-55
Author(s):  
N.-S. Park ◽  
H. Park
Keyword(s):  
Particle Image Velocimetry ◽  
Particle Image ◽  
Velocity Fields ◽  
Local Velocity ◽  
Mixing Condition ◽  
Particle Image Velocimetry Technique ◽  
Velocity Gradients ◽  
Image Velocimetry ◽  
Current Design ◽  
G Value

Recognizing the significance of factual velocity fields in a rapid mixer, this study focuses on analyzing local velocity gradients in various mixer geometries with particle image velocimetry (PIV) and comparing the results of the analysis with the conventional G-value, for reviewing the roles of G-value in the current design and operation practices. The results of this study clearly show that many arguments and doubts are possible about the scientific correctness of G-value, and its current use. This is because the G-value attempts to represent the turbulent and complicated factual velocity field in a jar. Also, the results suggest that it is still a good index for representing some aspects of mixing condition, at least, mixing intensity. However, it cannot represent the distribution of velocity gradients in a jar, which is an important factor for mixing. This study as a result suggests developing another index for representing the distribution to be used with the G-value.

scholarly journals A New Particle Image Velocimetry Technique for Turbomachinery Applications

2016 ◽  
Vol 138 (12) ◽  
Author(s):  
Sayantan Bhattacharya ◽  
Reid A. Berdanier ◽  
Pavlos P. Vlachos ◽  
Nicole L. Key
Keyword(s):  
Particle Image Velocimetry ◽  
Particle Image ◽  
Laser Sheet ◽  
Measurement Techniques ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Particle Image Velocimetry Technique ◽  
Optical Access ◽  
Tip Leakage ◽  
Image Velocimetry

Nonintrusive measurement techniques such as particle image velocimetry (PIV) are growing in both capability and utility for turbomachinery applications. However, the restrictive optical access afforded by multistage research compressors typically requires the use of a periscope probe to introduce the laser sheet for measurements in a rotor passage. This paper demonstrates the capability to perform three-dimensional PIV in a multistage compressor without the need for intrusive optical probes and requiring only line-of-sight optical access. The results collected from the embedded second stage of a three-stage axial compressor highlight the rotor tip leakage flow, and PIV measurements are qualitatively compared with high-frequency response piezoresistive pressure measurements to assess the tip leakage flow identification.

Abstract 14952: Volumetric Echocardiographic Particle Image Velocimetry (V-Echo-PIV)

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Ahmad Falahatpisheh ◽  
Arash Kheradvar
Keyword(s):  
Particle Image Velocimetry ◽  
Particle Image ◽  
Contrast Echocardiography ◽  
Ultrasound Contrast Agent ◽  
Three Dimensions ◽  
Small Scale ◽  
High Temporal Resolution ◽  
Two Dimensional ◽  
Particle Image Velocimetry Technique ◽  
Image Velocimetry

Introduction: The two-dimensional (2D) echocardiographic particle image velocimetry technique that was introduced in 2010 received much attention in clinical cardiology. Cardiac flow visualization based on contrast echocardiography results in images with high temporal resolution that are obtainable at relatively low cost. This makes it an ideal diagnostic and follow-up tool for routine clinical use. However, cardiac flow in a cardiac cycle is multidirectional with a tendency to spin in three dimensions rather than two-dimensional curl. Here, for the first time, we introduce a volumetric echocardiographic particle image velocimetry technique that robustly acquires the flow in three spatial dimensions and in time: Volumetric Echocardiographic Particle Image Velocimetry (V-Echo-PIV). Methods: V-Echo-PIV technique utilizes matrix array 3D ultrasound probes to capture the flow seeded with an ultrasound contrast agent (Definity). For this feasibility study, we used a pulse duplicator with a silicone ventricular sac along with bioprosthetic heart valves at the inlet and outlet. GE Vivid E9 system with an Active Matrix 4D Volume Phased Array probe at 30 Hz was used to capture the flow data (Figure 1). Results: The 3D particle field was obtained with excellent spatial resolution without significant noise (Figure 1). 3D velocity field was successfully captured for multiple cardiac cycles. Flow features are shown in Figure 2 where the velocity vectors in two selected slices and some streamlines in 3D space are depicted. Conclusions: We report successful completion of the feasibility studies for volumetric echocardiographic PIV in an LV phantom. The small-scale features of flow in the LV phantom were revealed by this technique. Validation and human studies are currently in progress.

scholarly journals Design Method and Verification of Electroosmosis-Vacuum Preloading Method for Sand-Interlayered Soft Foundation

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Yunliang Cui ◽  
Jianbo Tu ◽  
Xinquan Wang ◽  
Hongguo Diao ◽  
Qianru Ge
Keyword(s):  
Design Method ◽  
Simulation Method ◽  
Electrical Circuit ◽  
Test Results ◽  
Vacuum Preloading ◽  
Foundation Treatment ◽  
Vertical Drain ◽  
Soft Foundation ◽  
Prefabricated Vertical Drain ◽  
Preloading Method

The design method of electroosmosis-vacuum preloading for soft foundation treatment is not systematic and complete, thereby restricting the application of the technology in engineering. A design method for the electroosmosis-vacuum preloading treatment of sand-interlayered soft foundation is therefore presented. A compressible electrical prefabricated vertical drain is developed, and a vacuum sealing and draining system is designed for the application of the electroosmosis-vacuum preloading in sand-interlayered soft foundation. Calculation formulas of site resistance considering the interlayer and interface resistivity of the electrode are established to design the power supply and electrical circuit. A simple numerical simulation method is proposed to predict the ground settlement treated by electroosmosis-vacuum preloading. A field test of electroosmosis-vacuum preloading is designed using the suggested method, and comparison tests between the electroosmosis-vacuum preloading and the vacuum preloading are performed to verify the proposed technique. The test results show that the proposed design method is reasonable for the design of electroosmosis-vacuum preloading in engineering.

scholarly journals Data assimilation method to de-noise and de-filter particle image velocimetry data

2019 ◽  
Vol 877 ◽  
pp. 196-213 ◽  
Author(s):  
Jurriaan J. J. Gillissen ◽  
Roland Bouffanais ◽  
Dick K. P. Yue
Keyword(s):  
Particle Image Velocimetry ◽  
Data Assimilation ◽  
Particle Image ◽  
Particle Image Velocimetry Data ◽  
Reconstruction Error ◽  
Integration Time ◽  
Piv Measurement ◽  
Image Velocimetry ◽  
The Difference ◽  
Filter Particle

We present a variational data assimilation method in order to improve the accuracy of velocity fields $\tilde{\boldsymbol{v}}$, that are measured using particle image velocimetry (PIV). The method minimises the space–time integral of the difference between the reconstruction $\boldsymbol{u}$ and $\tilde{\boldsymbol{v}}$, under the constraint, that $\boldsymbol{u}$ satisfies conservation of mass and momentum. We apply the method to synthetic velocimetry data, in a two-dimensional turbulent flow, where realistic PIV noise is generated by computationally mimicking the PIV measurement process. The method performs optimally when the assimilation integration time is of the order of the flow correlation time. We interpret these results by comparing them to one-dimensional diffusion and advection problems, for which we derive analytical expressions for the reconstruction error.

scholarly journals Numerical Modelling of Prefabricated Vertical Drain for Soft Clay Using ABAQUS

2015 ◽  
Vol 773-774 ◽  
pp. 1502-1507
Author(s):  
Saiful Azhar Ahmad Tajudin ◽  
Mohd Fairus Yusof ◽  
I. Bakar ◽  
Aminaton Marto ◽  
Muhammad Nizam Zakaria ◽  
...  
Keyword(s):  
Pore Water Pressure ◽  
Water Pressure ◽  
Soft Soil ◽  
Soft Clay ◽  
Elastic Model ◽  
Clay Layer ◽  
Soil Consolidation ◽  
Consolidation Process ◽  
Vertical Drain ◽  
Prefabricated Vertical Drain

Construction, buildings and infrastructure founded on soft clays are often affected by settlement problem. Therefore, Prefabricated Vertical Drain (PVD) is one of the best solutions to accelerate soil consolidation by shortening the drainage path. In this study, numerical investigation was carried out to pursue a better understanding of the consolidation behavior of soft clay improved with PVD. The consolidation process accelerated by PVD with surcharge of 50 kPa was analysed using the ABAQUS software by adopting an elastic model. The aim of this study is to compare the settlement and the required time to fully consolidate the soft soil at different drain spacings (1.0 m, 1.5 m and 2.0 m) for two different thickness of the clay layer. The results shows that the time required to completely consolidate the soft soil for 12 m and 20 m thickness of clay layer with different spacings are in the range of 3 months to 66 months. The settlement rate and excess pore water pressure dissipation are increased when the spacing of the drain closer.

scholarly journals New approach of vacuum preloading with booster prefabricated vertical drains (PVDs) to improve deep marine clay strata

2018 ◽  
Vol 55 (10) ◽  
pp. 1359-1371 ◽  
Author(s):  
Yuanqiang Cai ◽  
Zhiwei Xie ◽  
Jun Wang ◽  
Peng Wang ◽  
Xueyu Geng
Keyword(s):  
Lateral Displacement ◽  
Water Pressure ◽  
Ground Improvement ◽  
Soft Soil ◽  
Marine Clay ◽  
Vacuum Preloading ◽  
Prefabricated Vertical Drains ◽  
New Approach ◽  
Study Results ◽  
Prefabricated Vertical Drain

This paper presented a new approach for ground improvement of deep marine clay in which the conventional booster tube in the current air booster vacuum preloading technology was replaced by a booster prefabricated vertical drain (PVD). In comparison to the ordinary PVD, the booster PVD could provide inflow channels for the compressed air when the booster pump was in operation. To examine the performance of this new air booster vacuum preloading technology, in situ field tests were conducted at Oufei sluice project in Wenzhou, China, where the thickness of the soft soil layers (i.e., marine clay) was more than 20 m. An extensive monitoring system was implemented to measure the vacuum pressure, pore-water pressure, settlement, and lateral displacement at this reclamation site. With the collected field monitoring data, a comprehensive data analysis was carried out to evaluate the extent of ground improvement. The study results depicted that this new air booster vacuum preloading technology was more effective for the ground improvement of the deep marine clay layers, in comparison to the conventional vacuum preloading technology.

Sign in / Sign up

Export Citation Format

Share Document