scholarly journals Undrained Pore Pressure Development on Cohesive Soil in Triaxial Cyclic Loading

2019 ◽  
Vol 9 (18) ◽  
pp. 3821 ◽  
Author(s):  
Andrzej Głuchowski ◽  
Emil Soból ◽  
Alojzy Szymański ◽  
Wojciech Sas
Keyword(s):  
Stress State ◽  
Cyclic Loading ◽  
Pore Pressure ◽  
Cohesive Soil ◽  
Soil Samples ◽  
Test Results ◽  
Soil Behavior ◽  
Pressure Development ◽  
Undrained Conditions ◽  
Excess Pore

Cohesive soils subjected to cyclic loading in undrained conditions respond with pore pressure generation and plastic strain accumulation. The article focus on the pore pressure development of soils tested in isotropic and anisotropic consolidation conditions. Due to the consolidation differences, soil response to cyclic loading is also different. Analysis of the cyclic triaxial test results in terms of pore pressure development produces some indication of the relevant mechanisms at the particulate level. Test results show that the greater susceptibility to accumulate the plastic strain of cohesive soil during cyclic loading is connected with the pore pressure generation pattern. The value of excess pore pressure required to soil sample failure differs as a consequence of different consolidation pressure and anisotropic stress state. Effective stresses and pore pressures are the main factors that govern the soil behavior in undrained conditions. Therefore, the pore pressure generated in the first few cycles plays a key role in the accumulation of plastic strains and constitutes the major amount of excess pore water pressure. Soil samples consolidated in the anisotropic and isotropic stress state behave differently responding differently to cyclic loading. This difference may impact on test results analysis and hence may change the view on soil behavior. The results of tests on isotropically and anisotropically consolidated soil samples are discussed in this paper in order to point out the main features of the cohesive soil behavior.

scholarly journals Mechanical response and pore pressure generation in granular filters subjected to uniaxial cyclic loading

2018 ◽  
Vol 55 (12) ◽  
pp. 1756-1768
Author(s):  
Jahanzaib Israr ◽  
Buddhima Indraratna
Keyword(s):  
Cyclic Loading ◽  
Pore Pressure ◽  
Pore Water ◽  
Mechanical Response ◽  
Pore Water Pressure ◽  
Axial Strain ◽  
Water Pressure ◽  
Internal Erosion ◽  
Excess Pore Water Pressure ◽  
Excess Pore

This paper presents results from a series of piping tests carried out on a selected range of granular filters under static and cyclic loading conditions. The mechanical response of filters subjected to cyclic loading could be characterized in three distinct phases; namely, (I) pre-shakedown, (II) post-shakedown, and (III) post-critical (i.e., the occurrence of internal erosion). All the permanent geomechanical changes such, as erosion, permeability variations, and axial strain developments, took place during phases I and III, while the specimen response remained purely elastic during phase II. The post-critical occurrence of erosion incurred significant settlement that may not be tolerable for high-speed railway substructures. The analysis revealed that a cyclic load would induce excess pore-water pressure, which, in corroboration with steady seepage forces and agitation due to dynamic loading, could then cause internal erosion of fines from the specimens. The resulting excess pore pressure is a direct function of the axial strain due to cyclic densification, as well as the loading frequency and reduction in permeability. A model based on strain energy is proposed to quantify the excess pore-water pressure, and subsequently validated using current and existing test results from published studies.

Pore Pressure Measurement in Blast-Induced Liquefaction Experiments

2005 ◽  
Vol 1936 (1) ◽  
pp. 210-220 ◽  
Author(s):  
Kyle M. Rollins ◽  
J. Dusty Lane ◽  
Emily Dibb ◽  
Scott A. Ashford ◽  
A. Gray Mullins
Keyword(s):  
Cyclic Loading ◽  
Pore Pressure ◽  
Pressure Measurement ◽  
Pressure Sensors ◽  
Extreme Environment ◽  
Soil Improvement ◽  
Deep Foundations ◽  
Soil Behavior ◽  
Pressure Transducers ◽  
Time Histories

Blast-induced liquefaction experiments have been conducted at a number of test sites to evaluate lateral foundation resistance and soil improvement techniques. Tests can be constructed at full scale without waiting for an earthquake. In this extreme environment, pore pressure transducers must survive transient blast pressures of 41.4 MPa (6,000 psi) yet have enough resolution to measure residual pore pressures of ±0.69 kPa (0.1 psi). Three transducer types were evaluated under these demanding conditions, and the piezoresistive transducer was found to be the most robust. These sensors were repeatedly subjected to extreme blast pressures and vibration, but they still provided accurate time histories of residual pore pressure. Although these piezometers are more expensive than other types, installation techniques allowed them to be recovered and reused in subsequent tests and thus reduced overall costs. These pore pressure sensors make it possible to define the extent of the liquefied zone during blast liquefaction experiments and to understand the soil behavior during cyclic loading of deep foundations.

scholarly journals Investigating the use of Boyle's Law to relate pore air pressures and volume changes in unsaturated triaxial samples

2019 ◽  
Vol 92 ◽  
pp. 07001
Author(s):  
Katherine Kwa ◽  
David Airey
Keyword(s):  
Cyclic Loading ◽  
Direct Measurement ◽  
Soil Samples ◽  
Triaxial Tests ◽  
Loading Conditions ◽  
Volume Changes ◽  
Pore Pressures ◽  
Undrained Conditions ◽  
Boyle’S Law ◽  
Measured Volume

Measuring the volume changes of unsaturated triaxial soil samples is one of the main challenges when performing unsaturated triaxial tests. Under fully undrained conditions, Boyle's Law can be used to calculate the sample's volume changes caused by the compression of air, as Boyle's Law relates changes in volume to changes in pore air pressures within the sample. This method has been used to calculate the volumetric strains and pore air pressures in unsaturated samples tested under cyclic loading conditions. However, the volume changes calculated from using Boyle's Law and the increases in pore air pressures, have not been compared with the actual measured volume changes of unsaturated samples. This study presents the pore pressures and compares the measured and predicted volumetric strains calculated from using Boyle's Law, in unsaturated triaxial samples that were tested cyclically. In some cases, using Boyle's Law was found to be similar to the volume changes estimated from direct measurement, but sometimes the method did not appear to work. Reasons for the discrepancies will also be discussed.

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.

scholarly journals A method of estimating excess pore pressures beneath embankments on sensitive clays

1979 ◽  
Vol 16 (4) ◽  
pp. 691-702 ◽  
Author(s):  
K. T. Law ◽  
M. Bozozuk
Keyword(s):  
Pore Pressure ◽  
Plane Strain ◽  
Strain Curve ◽  
Elastic Response ◽  
Test Results ◽  
Pore Pressures ◽  
Laboratory Test Results ◽  
Pore Pressure Response ◽  
Excess Pore Pressures ◽  
Excess Pore

A laboratory testing program for predicting undrained excess pore pressures beneath embankments constructed on sensitive clays is reported. A study of the pore pressure response, based on Henkel's equation applied to triaxial and plane strain tests performed on marine clay from South Gloucester, Ontario, provides a basis for comparing behaviour under conditions of axisymmetry and plane strain. Comparison shows that (1) pore pressure is smaller in plane strain than in axisymmetric conditions; (2) a below-elastic response prevails at the prepeak stage of the stress–strain curve; and (3) there is an elastic response at the peak.Finite element and modified elastic methods are developed for estimating undrained excess pore-water pressures from laboratory test results. The estimated values are used to evaluate the effect of consolidation under the center of an embankment during construction. The procedure is illustrated with case records.

Sign in / Sign up

Export Citation Format

Share Document