scholarly journals Analysis of Settlement Behaviour of Soft Ground Under Wide Embankment

2021 ◽  
Vol 16 (4) ◽  
pp. 153-175
Author(s):  
Xin Jiang ◽  
Xiaoli Chen ◽  
Yongguo Fu ◽  
Hanyan Gu ◽  
Jinming Hu ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Pore Pressure ◽  
Lateral Displacement ◽  
Excess Pore Pressure ◽  
Soft Ground ◽  
Finite Element Software ◽  
Distribution Rules ◽  
Embankment Slope ◽  
Settlement Behaviour ◽  
Excess Pore

An elastoplastic numerical model for calculating the consolidation settlement of wide embankment on soft ground is established using PLAXIS finite element software to investigate the settlement behaviour of soft ground under the wide embankment. The distribution rules are analysed and compared to narrow embankments, such as surface settlements of ground and embankment, lateral displacement of soft ground at the foot of embankment slope and excess pore pressure in soft ground. The influence rule of elastic modulus of soft ground on the settlement of soft ground under wide embankment is discussed. The results show that the settlement distributions of wide and narrow embankments on soft ground are “W” and “V” shapes, respectively. The maximum settlement of wide embankment is near the foot of the embankment slope, which is unequal to the settlement at the centreline of the embankment. The lateral displacement distribution rules of soft ground are both “belly” shaped at the foot of two types of embankments slope. However, the lateral displacement of the wide embankment is larger in each corresponding stage. During the construction period, the excess pore pressure in the soft ground under the wide embankment is much higher than that of the narrow embankment, so the post-construction consolidation time of the wide embankment is longer. Moreover, the macroscopic settlement rule of the wide embankment is still the same with the increase of elastic modulus of soft ground.

Effect of Geotextile and Prefabricated Vertical Drains Used in Soft Soil Foundation

2011 ◽  
Vol 197-198 ◽  
pp. 981-986
Author(s):  
Jie Qun Liu ◽  
Jin Long Liu
Keyword(s):  
Pore Pressure ◽  
Lateral Displacement ◽  
Soft Soil ◽  
Excess Pore Pressure ◽  
Prefabricated Vertical Drains ◽  
Vertical Drains ◽  
Lateral Displacements ◽  
Soil Foundation ◽  
Soft Soil Foundation ◽  
Excess Pore

Based on the generalized formulation of two dimensional Biot′s theory of consolidation, the effect of geotextile and prefabricated vertical drains (PVDs) using in soft soil foundation was studied with nonlinear finite element method. The dissipation of excess pore pressure, vertical settlement and lateral displacement of foundation were contrasted between foundations with and without PVDs. It is found that the vertical settlements become lager, the lateral displacements become less and the bulges at the toe of embankment become less at the same time of consolidation when PVDs are used. And the stability of embankment improved for the bearing capacity of soil enhanced with excess pore pressure dissipated fast. Meanwhile, the axial force of geotextile become less when PVDs are used. Those changes showed that the design of foundation can be optimized by shortening the time of consolidation when PVDs are used.

Numerical Analysis for Excess Pore Pressure Dissipation Process for Pressed Pile Installation

2013 ◽  
Vol 405-408 ◽  
pp. 133-137
Author(s):  
Tai Quan Zhou ◽  
Feng Tan ◽  
Cheng Li
Keyword(s):  
Finite Element ◽  
Pore Pressure ◽  
Excess Pore Pressure ◽  
Soil Behavior ◽  
Element Analysis ◽  
Dissipation Process ◽  
Pile Installation ◽  
Finite Element Software ◽  
Modified Cam Clay ◽  
Excess Pore

The finite element analysis is performed on the excess pore pressure dissipation for pressed pile installation using the ABAQUS finite element software. The modified Cam-Clay model is used to model the soil behavior. The finite slide contact model is used to model the pressed pile installation process. Based on the geology stratum of soils and drainage conditions, the excess pore pressure dissipation process is analyzed using the proposed method. The initial excess pore pressure distribution along the pile depth and the pile radius direction is obtained. The excess pore pressure dissipation after 98 days is analyzed.

Prediction of impending failure of embankments on soft ground

2003 ◽  
Vol 40 (1) ◽  
pp. 209-220 ◽  
Author(s):  
Gavan Hunter ◽  
Robin Fell
Keyword(s):  
Pore Pressure ◽  
Factor Of Safety ◽  
Ground Deformation ◽  
Lateral Displacement ◽  
Deformation Behaviour ◽  
Vertical Displacement ◽  
Pressure Response ◽  
Excess Pore Pressure ◽  
Soft Ground ◽  
Pore Pressure Response

The deformation behaviour and excess pore pressure response of 13 well-monitored embankments on soft ground that were constructed to failure have been analyzed. The analysis shows that by monitoring lateral displacement at the toe of the embankment and vertical displacement at the toe and about 5 m beyond the toe, the onset of impending failure of embankments on soft ground can be detected while the slope is at about 70–90% of the failure height. This equates to an actual factor of safety of around 1.25. Monitoring of borehole inclinometers at the toe of the embankment, cracking of the embankment, and the pore pressure response and deformation during pauses in construction can provide useful additional data for detection of an impending failure.Key words: embankment on soft ground, deformation, pore pressure, failure, factor of safety.

scholarly journals Design Optimisation Analysis of Isolating Wall for Separated Widening Embankment on Soft Ground

2021 ◽  
Vol 16 (2) ◽  
pp. 127-150
Author(s):  
Xin Jiang ◽  
Yongguo Fu ◽  
Linyu Li ◽  
Hanyan Gu ◽  
Yanjun Qiu
Keyword(s):  
Elastic Modulus ◽  
Lateral Displacement ◽  
Research Progress ◽  
Design Parameters ◽  
Soft Ground ◽  
Design Optimisation ◽  
Finite Element Software ◽  
Effect Mechanism ◽  
Optimal Values ◽  
Location Depth

In this paper, the typical cases of subgrade separated widening project in China are summarised. The research progress of subgrade separated widening and isolating wall applications are reviewed in highway reconstruction and extension. A numerical model is established based on the PLAXIS finite element software, considering both material nonlinearity and geometric nonlinearity. The effect mechanism of the isolating wall is discussed on the settlement control of the new and existing embankment on soft ground. The effect rule of the core design parameters of the isolating wall is revealed on the settlement disturbance of the existing embankment, such as location, depth, thickness and elastic modulus, and the weight rank of the influence is analysed. The results indicate that the isolating wall effectively reduces the lateral displacement and vertical settlement of the existing embankment, and there is an optimal design location for the isolating wall. In addition, with the increase of design parameters of the isolating wall, including depth, thickness and elastic modulus, the overall settlement of the existing embankment tends to be uniform, and there are optimal values. Furthermore, the depth of isolating wall is given priority, compared to location, thickness and elastic modulus during the isolating wall design process. The research results lay a theoretical foundation for the design optimisation of the isolating wall in the separated widening project of soft ground.

Vibro-Stone Column Reinforcement Mechanism and Numerical Analysis

2012 ◽  
Vol 446-449 ◽  
pp. 1940-1943
Author(s):  
Yang Liu ◽  
Hong Xiang Yan
Keyword(s):  
Numerical Simulation ◽  
Numerical Analysis ◽  
Pore Pressure ◽  
Numerical Procedure ◽  
Numerical Results ◽  
Excess Pore Pressure ◽  
Stone Column ◽  
Reinforcement Mechanism ◽  
Consolidation Theory ◽  
Excess Pore

Numerical simulation of vibro-stone column is taken to simulate the installation of vibro-stone column. A relationship based on test is adopted to calculate the excess pore pressure induced by vibratory energy during the installation of vibro-stone column. A numerical procedure is developed based on the formula and Terzaghi-Renduric consolidation theory. Finally numerical results of composite stone column are compared single stone column.

scholarly journals How deep does sand deposits in the Alentejo basin (Gulf of Cadiz) reach? Evaluating slope stability from bottom-current activities through time

2020 ◽  
Author(s):  
Davide Mencaroni ◽  
Roger Urgeles ◽  
Jonathan Ford ◽  
Jaume Llopart ◽  
Cristina Sànchez Serra ◽  
...  
Keyword(s):  
Pore Pressure ◽  
Sediment Supply ◽  
Excess Pore Pressure ◽  
Bottom Current ◽  
Gulf Of Cadiz ◽  
Strait Of Gibraltar ◽  
Gulf Of Cádiz ◽  
The Stability ◽  
Iberian Margin ◽  
Excess Pore

<p>Contourite deposits are generated by the interplay between deepwater bottom-currents, sediment supply and seafloor topography. The Gulf of Cadiz, in the Southwest Iberian margin, is a famous example of extensive contourite deposition driven by the Mediterranean Outflow Water (MOW), which exits the Strait of Gibraltar, flows northward following the coastline and distributes the sediments coming from the Guadalquivir and Guadiana rivers. The MOW and related contourite deposits affect the stability of the SW Iberian margin in several ways: on one hand it increases the sedimentation rate, favoring the development of excess pore pressure, while on the other hand, by depositing sand it allows pore water pressure to dissipate, potentially increasing the stability of the slope.</p><p>In the Gulf of Cadiz, grain size distribution of contourite deposits is influenced by the seafloor morphology, which splits the MOW in different branches, and by the alternation of glacial and interglacial periods that affected the MOW hydrodynamic regimes. Fine clay packages alternates with clean sand formations according to the capacity of transport of the bottom-current in a specific area. Generally speaking, coarser deposits are found in the areas of higher MOW flow energy, such as in the shallower part of the slope or in the area closer to the Strait of Gibraltar, while at higher water depths the sedimentation shifts to progressively finer grain sizes as the MOW gets weaker. Previous works show that at present-day the MOW flows at a maximum depth of 1400 m, while during glacial periods the bottom-current could have reached higher depths.</p><p>In this study we derived the different maximum depths at which the MOW flowed by analyzing the distribution of sands at different depths along the Alentejo basin slope, in the Northern sector of the Gulf of Cadiz.</p><p>Here we show how changes in sand distribution along slope, within the stratigraphic units deposited between the Neogene and the present day, are driven by glacial – interglacial period alternation that influenced the hydrodynamic regime of the MOW.</p><p>By deriving the depositional history of sand in the Alentejo basin, we are able to correlate directly the influence that climatic cycles had on the MOW activity. Furthermore, by interpreting new multi-channel seismic profiles we have been able to derive a detailed facies characterization of the uppermost part of the Gulf of Cadiz.</p><p>An accurate definition of sand distribution along slope plays an important role in evaluating the stability of the slope itself, e.g. to understand if the sediments may be subjected to excess pore pressure generation. As sand distribution is a direct function of the bottom-current transport capacity, the ultimate goal of this study is to understand how climate variations can affect the stability of submarine slope by depositing contourite-related sand.</p>

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