Pore water pressure increment model for saturated Nanjing fine sand subject to cyclic loading

2010 ◽  
Vol 9 (4) ◽  
pp. 569-576 ◽  
Author(s):  
Binghui Wang ◽  
Guoxing Chen ◽  
Dandan Jin
Keyword(s):  
Cyclic Loading ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Fine Sand ◽  
Pressure Increment

TIME TO THE END OF PRIMARY CONSOLIDATION (EOP) OF SOFT CLAYEY SOILS: CONCERNING THE EFFECT OF ATTERBERG’S LIMIT AND CYCLIC LOADING HISTORY

2019 ◽  
Vol 128 (2B) ◽  
pp. 29-41
Author(s):  
Trần Thanh Nhàn
Keyword(s):  
Cyclic Loading ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Clayey Soils ◽  
Loading History ◽  
Cyclic Shear ◽  
Wide Range ◽  
Primary Consolidation ◽  
Time Required

In order to observe the end of primary consolidation (EOP) of cohesive soils with and without subjecting to cyclic loading, reconstituted specimens of clayey soils at various Atterberg’s limits were used for oedometer test at different loading increments and undrained cyclic shear test followed by drainage with various cyclic shear directions and a wide range of shear strain amplitudes. The pore water pressure and settlement of the soils were measured with time and the time to EOP was then determined by different methods. It is shown from observed results that the time to EOP determined by 3-t method agrees well with the time required for full dissipation of the pore water pressure and being considerably larger than those determined by Log Time method. These observations were then further evaluated in connection with effects of the Atterberg’s limit and the cyclic loading history.

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.

scholarly journals Evaluation of local friction and pore-water pressure evolution along instrumented probes in saturated clay for large numbers of cycles

2019 ◽  
Vol 56 (12) ◽  
pp. 1953-1967
Author(s):  
Rawaz Dlawar Muhammed ◽  
Jean Canou ◽  
Jean-Claude Dupla ◽  
Alain Tabbagh
Keyword(s):  
Cyclic Loading ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Static Friction ◽  
Good Picture ◽  
Friction Resistance ◽  
Saturated Clay ◽  
Tip Resistance ◽  
Number Of Cycles

To investigate local friction mobilization along piles subjected to cyclic axial loadings, a calibration chamber experiment is presented based on the implementation of instrumented probes in specimens of saturated clay. Typical results obtained with a piezo-probe are presented, allowing not only tip resistance and local friction to be measured, but also the local pore-water pressure developed on the probe shaft. In addition, specific piezometers installed in the clay specimen allow a good picture to be obtained of the pore-water pressure field around the probe during installation and loading. After installation of the probe, a succession of monotonic and cyclic displacement-controlled loading phases is applied. Upon displacement-controlled cyclic loading of the piezo-probe up to a very large number of cycles (105 cycles), an initial degradation of local friction is observed followed by a subsequent reinforcement, which continues until the end of the cyclic sequence. The friction evolution is related to the evolution of the pore-water pressure measured during cyclic loading. In particular, the influence of the cyclic loading sequence on the post-cyclic static friction resistance is evaluated. A comparison is finally made with the results obtained with another type of probe, showing a good consistency between both types of results.

Membrane filter properties and application of the filter to undrained cyclic triaxial test of unsaturated materials

2017 ◽  
Vol 54 (8) ◽  
pp. 1196-1202 ◽  
Author(s):  
Hailong Wang ◽  
Junichi Koseki ◽  
Tomoyoshi Nishimura ◽  
Yukika Miyashita
Keyword(s):  
Hydraulic Conductivity ◽  
Cyclic Loading ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Membrane Filter ◽  
Water Pressure ◽  
Characteristic Curve ◽  
Loading Frequency ◽  
Loading Test ◽  
Pressure Plate

Properties of the membrane filter recently introduced as an alternative to the ceramic disk are revealed through diffusion and hydraulic conductivity tests. It is shown that diffusion of air through the membrane filter is significantly affected by suction magnitude and that hydraulic conductivity of the membrane filter can easily be affected by the quality of water used in the test. The application of the membrane filter to the soil-water characteristic curve tests (SWCC tests) shows that similar SWCCs can be obtained by employing pressure plate apparatuses with either the ceramic disks or the membrane filter installed, and that repeatability of the SWCC by using the membrane filter pressure plate apparatus is reasonably good. The application of the membrane filter to the undrained cyclic loading test of unsaturated sandy materials shows that the response (the duration to measure the equilibrated pore-water pressure of unsaturated materials) of the membrane filter pedestal in a modified triaxial system may be as short as ∼2 s in certain test conditions, and fairly good pore-water pressure and air pressure measurements can be obtained during undrained cyclic loading with a loading frequency of 0.1 Hz.

A study of infiltration on three sand capillary barriers

2004 ◽  
Vol 41 (4) ◽  
pp. 629-643 ◽  
Author(s):  
Hong Yang ◽  
H Rahardjo ◽  
E C Leong ◽  
D G Fredlund
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Soil Column ◽  
Fine Sand ◽  
Water Entry ◽  
Barrier Effect ◽  
Capillary Barrier ◽  
Soil Columns ◽  
Medium Sand

The capillary barrier effect was investigated by conducting infiltration tests on three soil columns of fine sand over medium sand, medium sand over gravelly sand, and fine sand over gravelly sand. The barrier effect was verified in the underlying layer of coarser material, and the water-entry values of the coarser layers were confirmed to be nearly equal to the residual matric suctions of the soils. The coarser layer of gravelly sand, which had a lower water-entry value, was more effective in forming a barrier than the coarser layer of medium sand, which had a higher water-entry value. When the capillary barrier was comprised of a coarser layer of gravelly sand, there was more water stored in the finer layer at the end of the drying stage than when the capillary barrier was comprised of a coarser layer of medium sand. Non-equilibrium static conditions of pore-water pressure profiles were observed in the three soil columns, and a generalized ultimate pore-water pressure profile of a capillary barrier system was proposed. In addition, the final volumetric water contents versus matric suctions of the soils as measured from the soil columns were reasonably consistent with the soil-water characteristic curves (SWCCs) of the soils, suggesting that the drying SWCC of a soil could also be obtained from the drying process in a soil column (or a capillary open tube). The drying SWCC could be established from measurements in the soil column up to a height corresponding to two times the residual matric suction head of the soil.Key words: capillary barrier, soil column, soil-water characteristic curve, pore-water pressure, water content, matric suction.

Pore-Pressure Accumulation and Soil Softening Around Pile Foundations for Offshore Wind Turbines

2012 ◽  
Author(s):  
Pablo Cuéllar ◽  
Matthias Baeßler ◽  
Werner Rücker
Keyword(s):  
Cyclic Loading ◽  
Pore Water ◽  
Wind Turbines ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Large Diameter ◽  
Constitutive Law ◽  
Offshore Wind ◽  
External Loading ◽  
Offshore Wind Turbines

The foundation of offshore wind turbines usually involves the installation of large-diameter steel piles in the seabed, either in monopile or multi-pile configurations (jacket, tripod, etc…), which have to ensure a proper fixity of the turbine during its whole service life-time. However, such foundations raise several challenges and novel questions, partly due to the special characteristics of the offshore environment (for instance, the large numbers of load cycles from wind and waves and the possible influence of transient changes of pore water pressure around the pile) and aggravated by their large diameter, reduced slenderness and elevated ratio of lateral to vertical loads (see Fig. 1). This paper studies the effects of cyclic lateral loading on the offshore piles focusing on the possibility of a progressive accumulation of residual pore water pressure within the saturated embedding soil. As it will be shown, this can lead to significant changes of their behaviour under external loading, which can potentially compromise the foundation’s stability or serviceability. The paper will also analyse some singular effects of an irregular loading (e.g. cyclic loading with variable amplitude), in particular the so-called “order effects” and the phenomena arising during a realistic storm of moderate magnitude, and discuss their potential for transient damages to the foundation’s stiffness. All these phenomena, which can lead to a loss of serviceability of the structure, have been investigated by the authors by means of a coupled bi-phasic analytical model of the offshore foundation featuring a versatile constitutive law suitable for the soil. The constitutive model, in the frame of the theory of Generalized Plasticity, can reproduce some complex features of cyclic soil behaviour such as the tendency for a progressive densification under cyclic loading, which is responsible for the soil liquefaction phenomena in undrained conditions. Finally, some implications of these issues for the practical design of offshore monopiles will be discussed and some specific recommendations for the design procedures will be outlined.

On the response of a poro-elastic bed to water waves

1978 ◽  
Vol 87 (1) ◽  
pp. 193-206 ◽  
Author(s):  
Tokuo Yamamoto ◽  
H. L. Koning ◽  
Hans Sellmeijer ◽  
Ep Van Hijum
Keyword(s):  
Porous Medium ◽  
Pore Water ◽  
Water Waves ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Three Dimensional ◽  
Fine Sand ◽  
Present Solution ◽  
Theoretical Results ◽  
Good Agreement

The problem of the response of a porous elastic bed to water waves is treated analytically on the basis of the three-dimensional consolidation theory of Biot (1941). Exact solutions for the pore-water pressure and the displacements of the porous medium are obtained in closed form for the case of waves propagating over the poro-elastic bed. The theoretical results indicate that the bed response to waves is strongly dependent on the permeabilitykand the stiffness ratioG/K’, whereGis the shear modulus of the porous medium andK’is the apparent bulk modulus of elasticity of the pore fluid. The earlier solutions for pore-water pressure by various authors are given as the limiting cases of the present solution. For the limitsG/K′→ 0 ork→ ∞, the present solution for pressure approaches the solution of the Laplace equation by Putnam (1949). For the limitG/K′→ ∞, the present solution approaches the solution of the heat conduction equation by Nakamuraet al.(1973) and Moshagen & Tørum (1975).The theoretical results are compared with wave tank experimental data on pore-water pressure in coarse and fine sand beds which contain small amounts of air. Good agreement between theory and experiment is obtained.

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