Modeling Riverbank Slope Reinforcement Using Anti-Slide Piles with Geocells

Geocells are increasingly used in engineering applications, but the design of riverbank slope reinforcements that use only geocells limits reinforcement performance. Moreover, the design and use of anti-slide piles with geocells are mainly based on experiences that are unsupported by theoretical models. In this paper, by combining the confinement effect and vertical action mechanism of geocells, the horizontal friction mechanism of the geocell layer and the vertical support mechanism of piles, a theoretical model of riverbank slope reinforced by anti-slide piles with geocells was constructed. In addition, to describe the mechanical behavior of a riverbank slope reinforced by anti-slide piles with geocells, the slip-resisting mechanism of the anti-slide pile with interaction between geocells and their internal filler is considered in the model. Furthermore, to investigate the influence of changes in water level on riverbank slope stability, the developed model takes into account settlement, lateral displacement, pile bending moment and pile axial force. The model predications were validated by the field measurement data. The results from a series of parametric studies show that the use of anti-slide pile and geocells can effectively reduce the settlement and the lateral displacement of a riverbank slope. The developed model could contribute to an optimal design of anti-slide pile with geocells for enhancing the stability of a riverbank slope.

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Study of Safety Influence Factor of Bridge Substructure in Loess Gulch

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.546-547.89 ◽

2012 ◽

Vol 546-547 ◽

pp. 89-96

Author(s):

Jin Wei ◽

Zhong Ju Feng ◽

Feng Ma

Keyword(s):

Soil Erosion ◽

Debris Flow ◽

Pile Foundation ◽

Influence Factor ◽

Lateral Displacement ◽

Bending Moment ◽

Zero Point ◽

Internal Force ◽

Prevention Measures ◽

The Stability

In this paper, the geology characteristics of loess gulch area were summarized. The mechanical models of the influence of landslide, debris flow and soil erosion on the safety of the pile foundation were created. The influence of the geology casualty on the safety of the pile foundation were analyzed. The analyses showed, when the pile foundation located the varied position of the loess gulch, the influence of soil erosion on the pile foundation character (acting force of pile side, free length of the pile, the first zero point position of the flexure curve, drawdown of the maximum bending moment, the increment of the lateral displacement, the drawdown of the lateral bearing capacity, the drawdown of the stability, etc.) were strikingly different. The calculation method of the pile and pier internal force was put forward under the function of landslide thrust and pressing force of debris flow. The corresponding prevention measures to different influencing factors were presented in the end.

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Influence of skirt reinforcement in passive zone on deformation of excavation

E3S Web of Conferences ◽

10.1051/e3sconf/202019802012 ◽

2020 ◽

Vol 198 ◽

pp. 02012

Author(s):

Peng-fei CHEN ◽

Xiao-nan GONG

Keyword(s):

Lateral Displacement ◽

Soft Soil ◽

Bending Moment ◽

Protection Scheme ◽

Soil Mixing ◽

Set Up ◽

The Stability ◽

Cement Soil ◽

Plaxis 3D ◽

Passive Area

In the design of the excavation protection scheme in the soft soil area, it is often necessary to set up cement-soil mixing piles in the passive area. In this way, the stability requirements of the excavation can be met, and the lateral displacement of the retaining pile can be greatly restricted. This paper uses PLAXIS 3D to establish a excavation model in a soft area, and discusses the influence of various parameters of the passive zone mixing pile on the deformation and force of the excavation. Within a certain range, as the cohesive force or secant modulus or reinforcement width or depth of the reinforcement area increases, the lateral displacement and settlement outside the pit will decrease. But when it exceeds a certain range, the decreasing trend becomes very slow. With the increase of the four parameters of the reinforcement zone, bending moments in opposite directions appear below the bottom of the excavation. Moreover, the value of the bending moment is getting larger and larger. Therefore, considering the force, it is not that the wider and deeper the reinforced zone is, the more advantageous is.

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Mechanical Stability Analysis of Subsea Wellhead for Deepwater Production to Earthquake Load

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.44-47.1061 ◽

2010 ◽

Vol 44-47 ◽

pp. 1061-1065

Author(s):

Wen Sheng Xiao ◽

Xiu Juan Lin ◽

Hong Yan Wang

Keyword(s):

Mechanical Stability ◽

Lateral Displacement ◽

Bending Moment ◽

Horizontal Displacement ◽

Lateral Force ◽

Angular Distortion ◽

Soil Reaction ◽

Seismic Load ◽

Earthquake Load ◽

The Stability

Subsea wellhead for deepwater production subjects to axial force, lateral force and bending moment under the seismic loading, the effect of subsea christmas tree and casing string’s gravity. Joint action of these forces makes it is possible that horizontal displacement exceeds the limitation and thus loses the stability. A mechanical analytical model of subsea wellhead for deepwater production is established on the basis of the pile foundation theories and material mechanics, the seismic load and behavior between casing string and formation are considered. The analyses on lateral displacement, angular distortion, bending moment and shear force show that the affection of lateral load is focus on the upper section of casing string, and the lateral displacement of subsea wellhead for deepwater production increases along with earthquake load and thus decreases stability. The stability improves notably with the increase of coefficient of soil reaction. Therefore it is necessary to obtain the on-the-spot geological data in shallow formation. The wellhead stability may be improved to different degrees by taking measures such as minimizing axial load, enhancing the conductor bending strenth, increasing the depth of the casing string in soil, reducing the outcropping length of the casing string.

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Driven Pile Effects on Nearby Cylindrical and Semi-Tapered Pile in Sandy Clay

Applied Sciences ◽

10.3390/app11072919 ◽

2021 ◽

Vol 11 (7) ◽

pp. 2919

Author(s):

Massamba Fall ◽

Zhengguo Gao ◽

Becaye Cissokho Ndiaye

Keyword(s):

Coupling Effect ◽

Lateral Displacement ◽

Bending Moment ◽

Adaptive Mesh ◽

Pile Driving ◽

Arbitrary Lagrangian Eulerian ◽

Axial Forces ◽

Tapered Pile ◽

Driven Pile ◽

The Impact

A pile foundation is commonly adopted for transferring superstructure loads into the ground in weaker soil. They diminish the settlement of the infrastructure and augment the soil-bearing capacity. This paper emphases the pile-driving effect on an existing adjacent cylindrical and semi-tapered pile. Driving a three-dimensional pile into the ground is fruitfully accomplished by combining the arbitrary Lagrangian–Eulerian (ALE) adaptive mesh and element deletion methods without adopting any assumptions that would simplify the simulation. Axial forces, bending moment, and lateral displacement were studied in the neighboring already-installed pile. An investigation was made into some factors affecting the forces and bending moment, such as pile spacing and the shape of the already-installed pile (cylindrical, tapered, or semi-tapered). An important response was observed in the impact of the driven pile on the nearby existing one, the bending moment and axial forces were not negligible, and when the pile was loaded, it was recommended to consider the coupling effect. Moreover, the adjacent semi-tapered pile was subjected to less axial and lateral movement than the cylindrical one with the same length and volume for taper angles smaller than 1.0°, and vice versa for taper angles greater than 1.4°.

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The effect of flexural–torsional buckling on the stability of timber members: a case study

SN Applied Sciences ◽

10.1007/s42452-021-04604-6 ◽

2021 ◽

Vol 3 (6) ◽

Author(s):

Osama A. B. Hassan

Keyword(s):

Axial Compression ◽

Bending Moment ◽

List Type ◽

Torsional Buckling ◽

Solution Methods ◽

Simplified Solution ◽

The Stability ◽

Flexural Torsional Buckling ◽

Building Engineering

Abstract This study investigates the stability of timber members subjected to simultaneously acting axial compression and bending moment, with possible risk for torsional and flexural–torsional buckling. This situation can occur in laterally supported members where one side of the member is braced but the other side is unbraced. In this case, the free side will buckle out of plane while the braced side will be prevented from torsional and flexural–torsional buckling. This problem can be evident for long members in timber-frame structures, which are subjected to high axial compression combined with bending moments in which the member is not sufficiently braced at both sides. This study is based on the design requirement stated in Eurocode 5. Solution methods discussed in this paper can be of interest within the framework of structural and building Engineering practices and education in which the stability of structural elements is investigated. Article Highlights This case study investigates some design situations where the timber member is not sufficiently braced. In this case, a stability problem associated with combined torsional buckling and flexural buckling can arise. The study shows that the torsional and/or flexural–torsional buckling of timber members can be important to control in order to fulfil the criteria of the stability of the member according to Eurocode 5 and help the structural engineer to achieve safer designs. The study investigates also a simplified solution to check the effect of flexural torsional buckling of laterally braced timber members.

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Centrifuge Modeling on Seismic Behavior of Pile in Liquefiable Soil Ground

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.479-480.1139 ◽

2013 ◽

Vol 479-480 ◽

pp. 1139-1143

Author(s):

Wen Yi Hung ◽

Chung Jung Lee ◽

Wen Ya Chung ◽

Chen Hui Tsai ◽

Ting Chen ◽

...

Keyword(s):

Seismic Behavior ◽

Soil Structure ◽

Lateral Displacement ◽

Bending Moment ◽

Soil Liquefaction ◽

Centrifuge Modeling ◽

Shaking Table ◽

Pile Head ◽

Liquefiable Soil ◽

Tip Mass

Dramatic failure of pile foundations caused by the soil liquefaction was founded leading to many studies for investigating the seismic behavior of pile. The failures were often accompanied with settlement, lateral displacement and tilting of superstructures. Therefore soil-structure interaction effects must be properly considered in the pile design. Two tests by using the centrifuge shaking table were conducted at an acceleration field of 80 g to investigate the seismic response of piles attached with different tip mass and embedded in liquefied or non-liquefied deposits during shaking. It was found that the maximum bending moment of pile occurs at the depth of 4 m and 5 m for dry sand and saturated sand models, respectively. The more tip mass leads to the more lateral displacement of pile head and the more residual bending moment.

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Seismic Response of Pile Groups Improved with Deep Cement mixing Columns in Liquefiable Sand: Shaking Table Tests

Canadian Geotechnical Journal ◽

10.1139/cgj-2020-0505 ◽

2021 ◽

Author(s):

Dingwen Zhang ◽

Anhui Wang ◽

Xuanming Ding

Keyword(s):

Seismic Behavior ◽

Lateral Displacement ◽

Bending Moment ◽

Pile Group ◽

Shaking Table ◽

Excess Pore Pressure ◽

Shaking Table Tests ◽

Pile Groups ◽

Acceleration Response ◽

Table Model

A series of shaking table model tests were performed to examine the effects of deep cement mixing (DCM) columns with different reinforcement depths on the seismic behavior of a pile group in liquefiable sand. Due to the DCM column reinforcement, the fundamental natural frequency of the model ground increases noticeably. The excess pore pressure of soils reduces with the increase of reinforcement depths of the DCM columns. Before liquefaction, the acceleration response of soils in the improved cases is obviously lower than that in the unimproved case, but the acceleration attenuation is greater after liquefaction in the unimproved case. Moreover, the lateral displacement of the superstructure, the settlement of the raft, and the bending moment of the piles in the improved cases are significantly reduced compared to those in the unimproved case, and the reduction ratios rise with the increase of reinforcement depth of the DCM columns. However, reinforcement by the DCM columns may result in the variation of the location of the maximum moment that occurs in the pile.

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Stability and collapse of holes in liquid layers

Journal of Fluid Mechanics ◽

10.1017/jfm.2018.680 ◽

2018 ◽

Vol 855 ◽

pp. 1130-1155 ◽

Cited By ~ 2

Author(s):

Cunjing Lv ◽

Michael Eigenbrod ◽

Steffen Hardt

Keyword(s):

Liquid Film ◽

Power Laws ◽

Theoretical Models ◽

Liquid Volume ◽

Capillary Length ◽

Minimum Thickness ◽

The Stability ◽

Film Profile ◽

Hole Closure ◽

Good Agreement

We investigate experimentally and theoretically the stability and collapse of holes in liquid layers on bounded substrates with various wettabilities. It is shown that for a liquid layer with a thickness of the order of the capillary length, a stable hole exists when the hole diameter is bigger than a critical value $d_{c}$. Consequently, a further increase of the liquid volume causes the hole to collapse. It is found that$d_{c}$increases with the size of the container, but its dependence on the contact angle is very weak. The experimental results are compared with theory, and good agreement is obtained. Moreover, we present investigations of the dynamics of the hole and the evolution of the liquid film profile after the collapse. The diameter of the hole during collapse and the minimum thickness of the liquid film shortly after the collapse obey different power laws with time. Simple theoretical models are developed which indicate that the collapse of the hole is triggered by surface tension and the subsequent closure process results from inertia, whereas the growth of the liquid column after hole closure results from the balance between the capillary force and inertia. Corresponding scaling coefficients are determined.

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Flexural-Torsional Vibration of Thin-Walled Beams Subjected to Combined Initial Axial Load and End Bending Moment: Application to the Design of Saw Tooth Blades

Shock and Vibration ◽

10.1155/2019/4509630 ◽

2019 ◽

Vol 2019 ◽

pp. 1-11

Author(s):

Van Binh Phung ◽

Anh Tuan Nguyen ◽

Hoang Minh Dang ◽

Thanh-Phong Dao ◽

V. N. Duc

Keyword(s):

Boundary Conditions ◽

Axial Load ◽

Stability Boundary ◽

Bending Moment ◽

Element Analysis ◽

The Finite Element Analysis ◽

Rayleigh Method ◽

Thin Walled ◽

The Stability ◽

Fixed End

The present paper analyzes the vibration issue of thin-walled beams under combined initial axial load and end moment in two cases with different boundary conditions, specifically the simply supported-end and the laterally fixed-end boundary conditions. The analytical expressions for the first natural frequencies of thin-walled beams were derived by two methods that are a method based on the existence of the roots theorem of differential equation systems and the Rayleigh method. In particular, the stability boundary of a beam can be determined directly from its first natural frequency expression. The analytical results are in good agreement with those from the finite element analysis software ANSYS Mechanical APDL. The research results obtained here are useful for those creating tooth blade designs of innovative frame saw machines.

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A fibre-based 2D-slit homogenizer concept for high-precision space-based spectrometer missions

CEAS Space Journal ◽

10.1007/s12567-021-00419-8 ◽

2022 ◽

Author(s):

Timon Hummel ◽

Claude Coatantiec ◽

Xavier Gnata ◽

Tobias Lamour ◽

Rémi Rivière ◽

...

Keyword(s):

Spectral Response ◽

Measurement Data ◽

Single Fibre ◽

Study Phase ◽

Total Size ◽

The Earth ◽

Spectral Sample ◽

Significant Performance ◽

The Stability ◽

High Level

AbstractThe measurement accuracy of recent and future space-based imaging spectrometers with a high spectral and spatial resolution suffer from the inhomogeneity of the radiances of the observed Earth scene. The Instrument Spectral Response Function (ISRF) is distorted due to the inhomogeneous illumination from scene heterogeneity. This gives rise to a pseudo-random error on the measured spectra. In order to assess the spectral stability of the spectrograph, stringent requirements are typically defined on the ISRF such as shape knowledge and the stability of the centroid position of the spectral sample. The high level of spectral accuracy is particularly crucial for missions quantifying small variations in the total column of well-mixed trace gases like $$\hbox {CO}_{2}$$ CO 2 . In the framework of the $$\hbox {CO}_{2}$$ CO 2 Monitoring Mission (CO2M) industrial feasibility study (Phase A/B1 study), we investigated a new slit design called 2D-Slit Homogenizer (2DSH). This new concept aims to reduce the Earth scene contrast entering the instrument. The 2DSH is based on optical fibre waveguides assembled in a bundle, which scramble the light in across-track (ACT) and along-track (ALT) direction. A single fibre core dimension in ALT defines the spectral extent of the slit and the dimension in ACT represents the spatial sample of the instrument. The full swath is given by the total size of the adjoined fibres in ACT direction. In this work, we provide experimental measurement data on the stability of representative rectangular core shaped fibre as well as a preliminary pre-development of a 2DSH fibre bundle. In our study, the slit concept has demonstrated significant performance gains in the stability of the ISRF for several extreme high-contrast Earth scenes, achieving a shape stability of $$<0.5{\%}$$ < 0.5 % and a centroid stability of $$<0.25 \ \text {pm}$$ < 0.25 pm (NIR). Given this unprecedented ISRF stabilization, we conclude that the 2DSH concept efficiently desensitizes the instrument for radiometric and spectral errors with respect to the heterogeneity of the Earth scene radiance.

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