scholarly journals Long-term dynamic bearing capacity of shallow foundations on a contractive cohesive soil

2021 ◽  
Author(s):  
Daniel R. Panique Lazcano ◽  
Rubén Galindo Aires ◽  
Hernán Patiño Nieto
Keyword(s):  
Bearing Capacity ◽  
Pore Water ◽  
Cyclic Load ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Friction Angle ◽  
Cohesive Soil ◽  
Cyclic Softening ◽  
Pore Water Pressures

AbstractThe calculation of the long-term dynamic bearing capacity arises from the need to consider the generation of maximum pore-water pressure developed from a cyclic load. Under suitable conditions, a long-term equilibrium situation would be reached, when pore-water pressures stabilized. However, excess pore-water pressure generation can lead to cyclic softening. Consequently, it is necessary to define both the cohesion and the internal friction angle to calculate the dynamic bearing capacity of a foundation in the long term, being necessary to incorporate the influence of the self-weight of soil and therefore the width of the foundation. The present work is based on an analysis of the results of cyclic simple shear tests on soil samples from the port of El Prat in Barcelona. From these experimental data, a pore-water pressure generation formulation was obtained that was implemented in FLAC2D finite difference software. A methodology was developed for the calculation of the maximum cyclic load that a footing can resist before the occurrence of the cyclic softening. The type of soil studied is a contractive cohesive soil, which generates positive pore-water pressures. As a numerical result, design charts have been developed for long-term dynamic bearing capacity calculation and the charts were validated with the application of a real case study.

scholarly journals Prediction of long-term settlement and evaluation of pore water pressure using particle filter

2019 ◽  
Vol 59 (1) ◽  
pp. 67-83 ◽  
Author(s):  
Toshifumi Shibata ◽  
Takayuki Shuku ◽  
Akira Murakami ◽  
Shin-ichi Nishimura ◽  
Kazunori Fujisawa ◽  
...  
Keyword(s):  
Particle Filter ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure

scholarly journals Field Test Research on Red Clay Slope under Atmospheric Action

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Kaisheng Chen
Keyword(s):  
Internal Friction ◽  
Water Content ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Red Clay ◽  
Failure Characteristics ◽  
Clay Slopes

By embedding water content sensors and pore water pressure sensors inside the red clay slope on-site in Guiyang, Guizhou, shear tests were performed on soil samples at different depths of the slope under different weather. The changes of water content, pore water pressure, and shear strength index of the slope inside the slope under the influence of the atmosphere were tracked and tested, and the failure characteristics and evolution of the red clay slope were analyzed. It is believed that the depth of influence of the atmosphere on red clay slopes is about 0.7 m, rainfall is the most direct climatic factor leading to the instability of red clay slopes, and the evaporation effect is an important prerequisite for the catastrophe of red clay slopes. The cohesion and internal friction angle of the slope soil have a good binary quadratic function relationship with the water content and density. The water content and density can be used to calculate the cohesion and internal friction angle. Failure characteristics of red clay slopes: the overall instability failure is less, mainly surface failure represented by gullies and weathering and spalling, and then gradually evolved into shallow instability failure represented by collapse and slump. The damage evolution law is as follows: splash corrosion and surface corrosion stage⟶ fracture development stage⟶ gully formation stage⟶ gully development through stage⟶ local collapse stage⟶ slope foot collapse stage.

Infiltration characteristics of two instrumented residual soil slopes

2003 ◽  
Vol 40 (5) ◽  
pp. 1012-1032 ◽  
Author(s):  
Illias Tsaparas ◽  
Harianto Rahardjo ◽  
David G Toll ◽  
Eng-Choon Leong
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Field Measurements ◽  
Residual Soil ◽  
Rainfall Runoff ◽  
Rainfall Events ◽  
Pore Water Pressures ◽  
Soil Slopes ◽  
Pressure Changes

This paper presents the analysis of a 12 month long field study of the infiltration characteristics of two residual soil slopes in Singapore. The field measurements consist of rainfall data, runoff data of natural and simulated rainfall events, and pore-water pressure changes during infiltration at several depths and at several locations on the two slopes. The analysis of the field measurements identifies the total rainfall and the initial pore-water pressures within the two slopes as the controlling parameters for the changes in the pore-water pressures within the slopes during infiltration.Key words: infiltration, rainfall, runoff, pore-water pressure, field measurements.

Field measurement of anchor forces, ground temperatures, and pore-water pressures behind a retaining structure in northwestern Ontario

1992 ◽  
Vol 29 (1) ◽  
pp. 112-116
Author(s):  
K. D. Eigenbrod ◽  
J. P. Burak
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Retaining Wall ◽  
Field Measurements ◽  
Strain Gauges ◽  
Ground Temperatures ◽  
Northwestern Ontario ◽  
Pore Water Pressures ◽  
Load Increase

Anchor forces, ground temperatures, and piezometric pressures were measured at a retaining wall in northwestern Ontario over a period of 2 years. The anchor forces were measured with strain gauges attached in pairs directly to the anchor rods. This method appeared practical in the field for time periods of less than 2 years as long as the strain gauges were carefully protected against moisture. The anchor forces increased from an average of 5 kN initially up to values of 50 kN during the winter periods and dropped during the summer periods back to the same values measured initially. The anchor forces were largely independent of pore-water pressure variations behind the wall. Rapid drawdown conditions, however, which were experienced during the second summer, were reflected in a load increase that was equivalent to the associated unloading effect in front of the wall. The pore-water pressures behind the wall were not noticeably affected by rapid drawdown, possibly due to the restraining effect of the anchors and the high rigidity of the low sheet pile wall. Ground temperatures at or below the groundwater table never dropped below 0 °C thus restricting the depth of frost penetration. Key words : anchor loads, freezing pressure, retaining walls, pore-water pressures, ground temperatures, field measurements.

scholarly journals Experiment Study of Lateral Unloading Stress Path and Excess Pore Water Pressure on Creep Behavior of Soft Soil

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Wei Huang ◽  
Kejun Wen ◽  
Dongsheng Li ◽  
Xiaojia Deng ◽  
Lin Li ◽  
...  
Keyword(s):  
Pore Water ◽  
Creep Behavior ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Soft Soil ◽  
Stress Path ◽  
Deviatoric Stress ◽  
Excess Pore Water Pressure ◽  
Pore Water Pressures ◽  
Excess Pore

The unloading creep behavior of soft soil under lateral unloading stress path and excess pore water pressure is the core problem of time-dependent analysis of surrounding rock deformation under excavation of soft soil. The soft soil in Shenzhen, China, was selected in this study. The triaxial unloading creep tests of soft soil under different initial excess pore water pressures (0, 20, 40, and 60 kPa) were conducted with the K0 consolidation and lateral unloading stress paths. The results show that the unloading creep of soft soil was divided into three stages: attenuation creep, constant velocity creep, and accelerated creep. The duration of creep failure is approximately 5 to 30 mins. The unloading creep behavior of soft soil is significantly affected by the deviatoric stress and time. The nonlinearity of unloading creep of soft soil is gradually enhanced with the increase of the deviatoric stress and time. The initial excess pore water pressure has an obvious weakening effect on the unloading creep of soft soil. Under the same deviatoric stress, the unloading creep of soft soil is more significant with the increase of initial excess pore water pressure. Under undrained conditions, the excess pore water pressure generally decreases during the lateral unloading process and drops sharply at the moment of unloading creep damage. The pore water pressure coefficients during the unloading process were 0.73–1.16, 0.26–1.08, and 0.35–0.96, respectively, corresponding to the initial excess pore water pressures of 20, 40, and 60 kPa.

scholarly journals Response of sediment to ice-sheet loading in northwestern Germany: effective stresses and glacier-bed stability

1997 ◽  
Vol 43 (145) ◽  
pp. 495-502 ◽  
Author(s):  
Jan A. Piotrowski ◽  
Anna M. Kraus
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Ice Sheet ◽  
Bed Deformation ◽  
Pore Water Pressures ◽  
Sediment Consolidation ◽  
Western Germany ◽  
Bed Stability ◽  
North Western

AbstractLaboratory tests on sediment over-ridden by the last ice sheet in north-western Germany reveal very low ice-induced pre-consolidation and high palaeo-pore-water pressures. Sediment consolidation at the base of the glacier was largely controlled by hydraulic properties of the substratum. Generally low permeabilities of the bed caused sustained high pore-water pressure in over-ridden sediments close to the flotation point. This implies a serious possibility of hydraulic lifting of the ice sheet. It is believed that the reduced basal coupling limited the transformation of glacier shear stress on to the bed sediments, which is indicated by a lack of sedimentological evidence for widespread pervasive bed deformation. Ice motion was probably focused at the glacier sole by some combination of sliding and ploughing. However, isolated spots with deformation occur, so that the subglacial system in the study area can be characterized as a stable/deforming mosaic.

Amelioration of Wolffersdorff Hypoplastic Constitutive Model Considering Intergranular Strain Tensor

2014 ◽  
Vol 638-640 ◽  
pp. 355-359
Author(s):  
Bao Lin Xiong ◽  
Chun Jiao Lu
Keyword(s):  
Constitutive Model ◽  
Pore Water ◽  
Cyclic Load ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Strain Tensor ◽  
Excess Pore Water Pressure ◽  
Intergranular Strain ◽  
Hypoplastic Constitutive Model ◽  
Excess Pore

Under cyclic load, the major shortcoming–ratcheting is produced in Wolffersdorff hypoplastic constitutive model. For eliminating ratcheting, Wolffersdorff hypoplastic model is ameliorated based on intergranular strain tensor. The added parameters in ameliorated model are determined by optimization method. Under cyclic load of triaxial consolidation undrained condition, the mechanics features of sand are described by the ameliorated Wolffersdorff hypoplastic constitutive model. Preliminary result shows that with increasing times of cyclic load excess pore water pressure is increased gradually and effective stress is reduced gradually. When effective is reduced to zero, the liquefaction happens. So in many projects, excess pore water pressure must dissipate by means of some measures. The sand liquefaction under the dynamic load is avoided.

Modelling unanticipated pore-water pressures in soft clays

1994 ◽  
Vol 31 (5) ◽  
pp. 773-778 ◽  
Author(s):  
Jianhua Yin ◽  
James Graham ◽  
Jack I. Clark ◽  
Longjun Gao
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Creep Behaviour ◽  
Soft Clay ◽  
Field Observations ◽  
Soft Clays ◽  
Secondary Compression ◽  
Pore Water Pressures ◽  
Clay Layers

Field observations in thin soft clay layers may show pore-water pressures that increase for some time after the loading is applied. Reasons for these observations are not well understood. The paper shows how an elastic viscoplastic constitutive model incorporated into the consolidation equation can predict these pore-water pressure increases in soils that exhibit significant creep behaviour (or secondary compression). The phenomenon has been related to relaxation in regions of the profile from which drainage has not yet begun. Key words : clay, consolidation, creep, secondary compression, viscous, relaxation, pore-water pressure, elastic–plastic.

Time Effect of the Pile Bearing Capacity in Dredger Fill

2013 ◽  
Vol 639-640 ◽  
pp. 630-638
Author(s):  
Hua Yang Lei ◽  
Qian Qian Lv
Keyword(s):  
Numerical Simulation ◽  
Bearing Capacity ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Ultimate Bearing Capacity ◽  
Time Effect ◽  
Second Phase ◽  
Excess Pore Water Pressure ◽  
Excess Pore

The dissipating of pore water pressure caused by pile sinking is one of the main factors resulting in time effect of ultimate bearing capacity of pile.The pore water pressure is monitored at each observing point during pile sinking and after that. With the pore pressure plan embedded in advance, by means of spot test in the process of pile sinking, under this geological conditions of the pile foundation by referring to the second phase project of the free port logistics processing zone in Dongjiang, Tianjin.The change law of the distribution and dissipation of excess pore water pressure with time, depth, radial distance and permeability coefficient of soil was also discussed. It’s found that the excess pore water pressure attenuates approximately linearly with the increase of the distance from the pile heart and the scope influenced is around 10d. As the numerical simulation accord with the test results effectively, promote the results then get the change rule of pile bearing capacity with time.The formula of pile bearing capacity about time effect in dredge fill was deduced for engineering reference.The effect of soil internal friction angle on the ultimate bearing capacity of pile was discussed. Numerical simulation shows that the ultimate bearing capacity of pipe pile increases over time and keeps stable after 20d.The ultimate limit bearing capacity is 1473kN with increase of 12.3%, the time when it reaches the stable state is in accord with the excess pore water pressure dissipation monitored at each observing point. The larger the internal frictional angle of soil becomes, the more the ultimate bearing capacity is. The angle exceeding 20°,the bearing capacity would not increase as internal frictional angle of soil increases.

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