Tank Settlement Research Articles

Quasi-distributed low-coherent optical sensors for in-field monitoring the harmonic settlement of oil tank

Quasi-distributed low-coherent optical sensors for in-field monitoring the harmonic settlement of oil tank

Three-Dimensional Analyses of Long-Term Settlement of Storage Tanks Supported by a Large Piled-Raft Foundation System

Three-Dimensional Analyses of Long-Term Settlement of Storage Tanks Supported by a Large Piled-Raft Foundation System

Vision measurement system for tank settlement using Hanning-window changing density fringes

Vision measurement system for tank settlement using Hanning-window changing density fringes

Construction of a digital twin model for vertical storage tank deformation assessment using terrestrial laser scanning technology

The foundational settlement and deformation of vertical storage tanks are crucial factors influencing their safe operation. To enable rapid deformation assessment of storage tanks, this paper combines point cloud data acquired through terrestrial laser scanning with relevant data processing algorithms to construct a digital twin (DT) model. This achieves high-precision automated detection of tank deformation, facilitating the digital transformation of deformation assessment and offering an integrated detection strategy. First, Euclidean distance clustering is applied to the point cloud, and the point density within clusters is statistically analyzed using a Gaussian distribution. This results in a collection of point clusters within one standard deviation, effectively filtering out outliers and noise points, which facilitates the rapid global registration of the point cloud. Second, in order to quickly segment tank point clouds in the scene, back propagation neural network classification learning based on principal component analysis information is used. The point cloud model is combined with the fitting information of slices to generate a DT model, whose deformation can be evaluated through comparison with appropriate storage tank specifications, taking radial deformation, tank inclination, and foundation settlement as indicators.

Seasonal temperature‐related variation of humus tank settlement efficiency

AbstractThis study uses several years of effluent quality data from 43 sites where online monitoring has been operational for many years resulting in the accumulation of high‐resolution data sets. The data show a highly repeatable, seasonal dependence of effluent turbidity on temperature. This has been modelled with simple techniques producing a generic model that is neither data hungry nor requires site calibration. Viscosity‐based mechanisms are proposed and discussed. These mechanisms differ from conventional assumptions of suspended solids peaks being solely flow related and or ascribed to ‘spring sloughing’. The proposal is that the organic loading of the filter and the physical temperature effects on settlement velocity are both as influential as hydraulic loading in determining effluent suspended solids concentration. Application of the models enables improved design for new/upgraded units and more accurate capacity assessment of trickling filters and humus tanks enabling improved operational risk management of compliance failure.

Numerical Analysis of Fire Water Storage Tank under Seismic Loading

Maintenance and continuously monitoring the condition of above ground storage tanks are significant when the tanks are placed in service. The American Petroleum Institution (API) 653 and other international codes provides the minimum requirements for inspection & maintaining the integrity of tanks during its service. The tank settlement is one of the major threats for tank’s integrity. In this paper, a storage tank is assessed for uniform settlement under various loading condition such as seismic, dead load, static load, corrosion loss of shell plate etc. In the present study, a finite element model is designed with uniform settlement condition and study of its governing hoop stress at shell plate has been carried out under different loading conditions. A fire water storage tank (constructed with IS 2060 GR. B material) and different seismic zones in India are taken for this study. The finite element analysis simulation shows that increase of hoop stress in the bottom shell course due to uniform settlement, the decrease in plate thickness and with different seismic active regions. Moreover, the maximum stresses have been observed at shell bottom course (close to bottom plate).

Acoustic Emission Data Analysis of Tank Settlement

The uneven settlement around the tank and the corrosion of the bottom are main factors affecting the safe operation of the tank, so it is necessary to monitor the settlement and corrosion of the tank in real time to prevent and eliminate the hidden danger in time. In this paper, the large crude oil storage tank is taken as the research object to carry out uneven settlement monitoring and acoustic emission dynamic detection. By analyzing the measured settlement data and acoustic emission characteristic parameters, the author explores the influence of tank settlement on acoustic emission signal of tank floor corrosion, so as to provide reference for the extension of service life of storage tank and anti-corrosion work of storage tank.

Analysis of Uneven Settlement of Large Oil Storage Tank

The uneven settlement of large oil storage tank will not only cause the tank wall to be elliptical and the upper floating plate to be blocked, but also cause the tank body to fall. In order to study the influence of uneven settlement on the tank structure, this paper takes 50000m3 oil storage tank as an example, uses the finite element simulation method to explore the influence of uneven settlement of different scales of large tank foundation on the overall stress characteristics of the tank, and obtains the storage. The influence of uneven settlement of tank foundation on the mechanics of tank body, tank bottom and large corner joint. It can provide some guidance for tank management and evaluation.

Creep characteristics and pore water pressure changes during loading of water storage tank on soft organic soil

ABSTRACT Peat ground is widely distributed throughout the southern part of Iraq. Peat contains a large amount of organic matter and has a very high natural water content. This study discusses results of settlement of water storage tank constructed in southern oilfield of Iraq. The first part of this study deals with field experimental works, which included drilling boreholes and evaluating the mechanical soil properties. The second part is conducted using finite element method through the 3D software, adopting the Soft Soil Creep Model and Soft Soil Model. Results showed that the secondary settlement has greatly affected the behaviour and final settlement of the tank, and the Soft Soil Creep Model is a better representative to the field settlement than Soft Soil Model. The results of Soft Soil Creep model are greater than those of Soft Soil Model for vertical displacement, horizontal displacement and pore water pressure because of secondary compression effect.

Variational approach for settlement analysis of circular plate on multilayered soil

• A semi-analytical method is developed for the analysis of a uniformly-loaded circular plate on a multilayered soil. • The method can analyze a thin circular plate's flexural behavior on any number of soil layers. • A parametric study on two- and three-layered soils highlights important insights about plate-layered soil interactions. • Charts that can facilitate the analysis of differential settlement of concrete tanks are provided. A continuum-based analysis method is developed to analyze a uniformly-loaded circular plate founded on a multilayered soil deposit. The multilayered soil deposit forms a semi-infinite half space, and the behavior of each soil layer is assumed to be linear elastic. The plate is considered to be isotropic, homogeneous, and linear elastic. We apply variational principles to obtain the governing differential equations of the plate-layered soil system and solve them semi-analytically. We then compare results from the present analyses with those from finite element analysis. Using the proposed analysis method we perform a parametric study, results from which provide important insights into the effects of soil layering – such as the thicknesses and stiffness ratios of multiple soil layers – on the flexural behavior of the circular plate. Analyses for wide ranges of plate-to-soil stiffness ratios provide further insights on plate-soil interactions.

Results of Static Loading Tests on Single Piles and on Pile-Supported LPG Tanks

Full-scale static loading tests on eight single test piles and hydrotests on two 50-m diameter tanks supported on 849 piles intended for storing refrigerated gas were performed at Cai Mep Industrial Park approximately 90 km southeast of Ho Chi Minh City, Vietnam. The test piles were precast concrete piles installed through 21 m of soft clay into dense sand to about 45 m depth below ground surface. Four piles were installed by driving and four by jacking. The maximum pile test loads were 3000 kN, which was well below any ultimate resistance, but showed that the tank-foundation piles (to be installed by jacking) could expect to shorten about 3 mm for the 750-kN working load. Each tank was hydro-tested to 636-MN maximum service load, which load was held constant for 1 week, while monitoring the tank settlement at benchmarks placed along the tank perimeters. The records showed the tank perimeters to settle about 15 mm in addition to an about 3-mm pile shortening. Back-analysis of the tank foundation modeled as flexible equivalent rafts at the pile toe level showed that the settlement of the tank center was about three times larger than that of the perimeter. Analysis of long-term settlements indicated that, under service loading, the tank perimeters and centers will settle an additional about 100 mm and 300 mm, respectively. Due to a 3 m thick fill placed over the site causing the clay to consolidate, the ground surface is expected to settle more than 1 m over the long-term. The general subsidence will affect the perimeter piles and transfer load to the interior piles. However, because the pile neutral plane is located in the sand below the clay, downdrag is not an issue for the piled foundation. The drag force will be well below the limit of the pile axial structural strength.

Modeling of storage tank settlement based on the United States standards

Up to 60% of storage tanks in operation have uneven settlement of the outer bottom contour, which often leads to accidents. Russian and foreign regulatory documents have different requirements for strain limits of metal structures. There is an increasing need for harmonizing regulatory documents. The aim of this study is to theoretically justify and to assess the possibility of applying the U.S. standards for specifying the allowable settlement of storage tanks used in Russia. The allowable uneven settlement was calculated for a vertical steel tank (VST-20000) according to API-653, a standard of the American Petroleum Institute. The calculated allowable settlement levels were compared with those established by Russian standards. Based on the finite element method, the uneven settlement development process of a storage tank was modeled. Stress-strain state parameters of tank structures were obtained at the critical levels established in API-653. Relationships of maximum equivalent stresses in VST metal structures to the vertical settlement component for settlement zones of 6 to 72 m in length were determined. When the uneven settlement zone is 6 m in length, the limit state is found to be caused by 30-mm vertical settlement, while stresses in the wall exceed 330 MPa. When the uneven settlement zone is 36 m in length, stresses reach the yield point only at 100-mm vertical settlement.

Modeling of storage tank settlement based on the United States standards

Up to 60% of storage tanks in operation have uneven settlement of the outer bottom contour, which often leads to accidents. Russian and foreign regulatory documents have different requirements for strain limits of metal structures. There is an increasing need for harmonizing regulatory documents. The aim of this study is to theoretically justify and to assess the possibility of applying the U.S. standards for specifying the allowable settlement of storage tanks used in Russia. The allowable uneven settlement was calculated for a vertical steel tank (VST-20000) according to API-653, a standard of the American Petroleum Institute. The calculated allowable settlement levels were compared with those established by Russian standards. Based on the finite element method, the uneven settlement development process of a storage tank was modeled. Stress-strain state parameters of tank structures were obtained at the critical levels established in API-653. Relationships of maximum equivalent stresses in VST metal structures to the vertical settlement component for settlement zones of 6 to 72 m in length were determined. When the uneven settlement zone is 6 m in length, the limit state is found to be caused by 30-mm vertical settlement, while stresses in the wall exceed 330 MPa. When the uneven settlement zone is 36 m in length, stresses reach the yield point only at 100-mm vertical settlement.

Large Oil Tank Settlement and Tilt During Hydraulic Testing

An example of the development of settlement and inadmissible tilt of an oil tank during hydraulic testing is presented. Data from engineering and geological research as well as a combined numerical calculation of the base and foundation by the finite-element method did not permit predicting the considerable tilt of the tank during hydraulic testing.

해저 연약지반 보강 조건에 따른 인공어초 침하 거동에 대한 실험적 연구

바다 자원의 조성을 위해 시설되는 인공어초는 해저 연약지반에 설치될 경우 침하 및 세굴에 의한 기능 상실이 발생할 수 있다. 따라서 본 연구에서는 해저 연약지반의 보강에 따른 인공어초의 침하 거동을 알아보기 위해 모래, 실트 및 점토 지반을 각각 조성하여 관입실험, 침하실험 등과 같은 다양한 실내실험을 수행하였다. 무보강(unreinforced), 지오그리드(geogrid) 보강 및 하이브리드 대나무매트(hybrid bamboo mat, HBM) 보강과 같은 3종류의 보강과 보강재의 면적에 따른 특성을 살펴보았다. 실험 결과 보강재의 면적이 증가할수록 보강 효과가 증가하는 경향을 보였으며, HBM이 지오그리드 단일 보강에 비해 더 뛰어난 보강 효과를 보였다. Seabed settlement and erosion sometimes occurr when a artificial reef is installed in soft seabed. Therefore, this study carried out CBR test and water tank settlement test to investigate settlement behavior of artificial reef according to reinforcement characteristics such as reinforced types and reinforced area. Soil types of ground are sand, silt and clay deposits. Three reinforced types were prepared: unreinforced, geogrid and hybrid bamboo mat(HBM) with different reinforced area. Laboratory test results indicated that reinforced artificial reef improved bearing capacity of ground and reduced settlement as reinforced area increased. Especially, reinforced HBM provided more bearing capacity and less settlement than reinforced geogrid.

Research of Curve Fitting Method on the Measured Settlement of Tanks

The settlement data of oil storage tanks made of steel are measured by the measurement points located around the base of the tank wall. The measured settlement data need to be curve fitted in order to reflect the settlement distribution around the whole tank wall base. Considering about the disadvantage of measured settlement data treatment methods on tanks in current standards, an optimization method of curve fitting on the measured settlement data is presented. The Fourier series expansion is used to analyze the measured settlement data, the fitting curves and mean square error according to different order are obtained. The fitting curve with minimum mean square error is selected as the most appropriate one that reflects the actual displacement of the tank base. The optimization method of curve fitting present is applied to analyze the measured settlement data obtained from the floating roof tank and the fixed roof tank. Results show that different effects can be obtained with different order of the fitting curve. Curve fitting referring to different order is necessary to the measured settlement data in actual engineering in order to find the most appropriate one that reflects the real tank base displacement distribution.

Finite Element Analysis on Instantaneous Deformation and Consolidation Deformation of Saturated Soft Clay Foundation

Deformation analysis of foundation is an important research field in geotechnical engineering, especially analysis on instantaneous deformation and consolidation deformation of saturated soft clay foundations. In this paper, a computation model of instantaneous deformation and consolidation deformation was built on the basis of Biot Consolidation Theory and consideration of mechanism of instantaneous deformation and consolidation deformation and consideration of interrelation of both deformations. A method was proposed to determine initial pore water pressure in soil. Nonlinearity of soil deformation under drainage conditions was considered by combining Duncan-Zhang model with compaction curve of soil, and failure soil elements were processed by Mohr-Coulomb Failure Criteria. By numerical simulation, a nonlinear axi-symmetric FEM program was complied to solve foundation deformation and applied in calculation of soft ground tank settlement. Results show that the method presented in this paper is efficient and suitable to analyze instantaneous deformation and consolidation deformation.

Stability Analysis of Floating-Roof Tanks under Differential Settlement

Vertical cylindrical steel tanks are sensitive to differential settlement beneath the tank wall. Most previous studies were based on idealized harmonic settlement, however, for thin shell structures of high nonlinear behavior, it is obviously inappropriate to obtain the results under real settlement by simple summation of harmonic solutions. Real settlement of steel tanks can be grouped into two types - global differential settlement and local differential settlement. This paper examines the nonlinear response and stability behavior of floating-roof steel tanks under both types of settlement. It is shown that, for tanks under global differential settlement, local buckling occurs at the eave ring, followed by a stable post-buckling behavior, and final failure is by overall buckling of the tank shell; while for tanks under local differential settlement, the structural response is related to the degree of localization. At highly localized settlement, local snap-through buckling occurs at the tank wall, but it does not lead to a serious consequence, and the post-buckling behavior can also be utilized in design.

Structure and accumulation conditions of Upper Maastrichtian sediments at the Tankovoe (Tank) Settlement (Southwest Crimea)

A detailed layer-by-layer description of the most complete section of the Upper Maastrichtian Rocks at the Tankovoe Settlement in the Bel’bek River valley in the Sevastopol’ District of the Southwest Crimea is presented along with microscopic description of the rocks and an analysis of ichnofossils. Late Maastrichtian paleogeographic and paleoclimatologic issues of the northern margin of the Tethys Ocean are discussed. A sedimentation model explaining the origin of the cyclic succession is suggested.

Evaluation of sheet pile-ring countermeasure against liquefaction for oil tank site

The evaluation of a countermeasure against liquefaction which uses a sheet pilering for oil tank sites is presented. The simulation of earthquake responses observed at tank sites with and without sheet pile-ring is first performed to validate the three-dimensional finite element numerical model. Using the numerical model, liquefaction analysis is performed and the excess pore water pressure generated in the soil and the settlement of tank are investigated. The comparison of two- and three-dimensional models is also conducted to assess the applicability of two-dimensional analysis. The results show that the numerical model could simulate the observed earthquake responses of tank-ring-soil system, and that the excess pore water pressure and the settlement of the tank could be significantly reduced using a sheet pile-ring. The two-dimensional analysis proves to be capable of representing the main features of the dynamic response of the three-dimensional tank-ring-soil system.