A unified approach to densification and liquefaction of cohesionless sand in cyclic shearing

1979 ◽  
Vol 16 (4) ◽  
pp. 659-678 ◽  
Author(s):  
S. Nemat-Nasser ◽  
A. Shokooh
Keyword(s):  
Experimental Data ◽  
Void Ratio ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Unified Theory ◽  
Saturated Sand ◽  
Unified Approach ◽  
Homogeneous Sample ◽  
Excess Pore Water Pressure ◽  
Excess Pore

When submitted to cyclic shearing, loose dry sand densifies, and undrained saturated sand may liquefy. Based on energy considerations, a unified theory for densification and liquefaction of a homogeneous sample of cohesionless sand is proposed. It is observed that these phenomena involve rearrangement of grains in microscale, requiring an expenditure of a certain amount of energy, which increases as the void ratio approaches its minimum value and decreases as the excess pore water pressure increases. On the basis of rough estimates, explicit relations are developed for both the densification and liquefaction phenomena, and the results are applied to predict relevant available experimental data.

scholarly journals Numerical Simulation of the Construction Process of Long Spiral CFG Piles

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Taotao Wang ◽  
Siyi Du
Keyword(s):  
Pore Water ◽  
Void Ratio ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Engineering Practice ◽  
Drilling Process ◽  
Construction Process ◽  
Saturated Sand ◽  
Excess Pore Water Pressure ◽  
Excess Pore

A numerical model for the construction process of long spiral CFG piles is established based on the coupled Eulerian–Lagrangian method. The construction process is divided into drilling process and concrete pouring process for modeling. The influence of long spiral CFG piles construction on saturated sand foundation is studied, and dynamic responses, changes of pore water pressure, and void ratio of saturated sand foundation are obtained. The rationality and accuracy of the simulation results are proved by comparing with the field test data and calculation results of the theory of cylindrical cavity expansion. The presented numerical results prove that the vibration load generated during the construction acts on saturated soil in the form of irregular reciprocating shear forces, which leads to a large excess pore water pressure in the soil and an increase in soil void ratio. Both the excess pore water pressure field generated during the construction and the soil pore ratio after the construction show a parabolic distribution in the vertical direction. The research results can provide reference and theoretical basis for future research and engineering practice.

A Practical Saturated Sand Elastic-Plastic Dynamic Constitutive Model and Application

2012 ◽  
Vol 446-449 ◽  
pp. 1621-1626 ◽  
Author(s):  
Yan Mei Zhang ◽  
Dong Hua Ruan
Keyword(s):  
Constitutive Model ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Stone Columns ◽  
Saturated Sand ◽  
Multidimensional Model ◽  
Excess Pore Water Pressure ◽  
Elastic Plastic ◽  
Excess Pore

A practical saturated sand elastic-plastic dynamic constitutive model was developed on the base of Handin-Drnevich class nonlinear lag model and multidimensional model. In this model, during the calculation of loading before soil reaches yielding, unloading and inverse loading, corrected Handin-Drnevich equivalent nonlinear model was adopted; after soil yielding, based on the idea of multidimensional model, the composite hardening law which combines isotropy hardening and follow-up hardening, corrected Mohr-Coulomb yielding criterion and correlation flow principle were adopted. A fully coupled three dimension effective stress dynamic analysis procedure was developed on the base of this model. The seismic response of liquefaction foundation reinforced by stone columns was analyzed by the developed procedure. The research shows that with the diameter of stone columns increasing, the excess pore water pressure in soil between piles decreases; with the spacing of columns increasing, the excess pore water pressure increases. The influence of both is major in middle and lower level of composite foundation.

scholarly journals Analysis of Large-Strain Consolidation Behavior of Soil with High Water Content in Consideration of Self-Weight

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Yupeng Cao ◽  
Jian Yang ◽  
Guizhong Xu ◽  
Jianwen Xu
Keyword(s):  
Pore Water ◽  
Void Ratio ◽  
Pore Water Pressure ◽  
Large Strain ◽  
Water Pressure ◽  
Average Degree ◽  
High Water Content ◽  
Excess Pore Water Pressure ◽  
Degree Of Consolidation ◽  
Excess Pore

Based on the axisymmetric large-strain consolidation (ALSC) model with the void ratio as the variable under equal strain condition, difference schemes of model’s equation, initial condition, and boundary condition were given. Taking phosphatic clay in Florida as a research object, the consolidation behaviors of soil with high water content by axisymmetric large-strain theory and one-dimensional large-strain theory were analyzed. The effect of different kinds of consolidation theories and self-weight stress on an average degree of consolidation was evaluated. The development of the void ratio and excess pore water pressure along the soil layer was clarified. The results show that the theoretical value of Terzaghi’s consolidation degree is always less than that of ALSC (Us, the average degree of consolidation defined by strain)-vertical drainage in the consolidation process. Terzaghi’s solution overestimates the dissipation rate of excess pore water pressure during the earlier consolidation period but underestimates it during the later consolidation period. The degree of consolidation calculated by Hansbo develops faster than ALSC (Up, the average degree of consolidation defined by stress)-radial drainage, but slower than ALSC (Us)-radial drainage. In the ALSC model, Us is always been faster than Up. The effect of self-weight on the consolidation degree of axisymmetric large-strain consolidation theory is relatively small (maximum error is less than 16%), while it can accelerate the consolidation rate of soil in one-dimensional large-strain consolidation theory largely. When only the vertical drainage occurs, the consolidation rate in the middle of the soil is obviously lagging the upper and lower parts, while the radial drainage can reduce the void ratio and the excess pore water pressure along the soil layer uniformly and more rapidly.

scholarly journals Mechanical behaviour of calcareous waste under consolidated drained triaxial compression testing in saturated conditions

2019 ◽  
Vol 106 ◽  
pp. 01016
Author(s):  
Jakub Zięba
Keyword(s):  
Mechanical Behaviour ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Triaxial Compression ◽  
Soil Samples ◽  
Excess Pore Water Pressure ◽  
Stiffness Properties ◽  
Construction Purpose ◽  
Strength And Stiffness ◽  
Excess Pore

The article presents the mechanical behaviour of calcareous waste under consolidated and drained condition in Triaxial compression test (CD). The host material currently being considered for the construction purpose of several buildings in Poland. One of the location of calcareous waste is in Łagiewniki area (in Cracow) [1,2]. In this work, particular attention has been paid to the to ensure fully saturation for all the tested soil samples and avoid generation of unwanted excess pore water pressure during shearing stage. The saturation level of soil samples was estimated based on Skempton’s law (B>0.95). CD Triaxial test have been conducted in order to derive information on its strength and stiffness properties.

Stress–strain pattern–based criterion to assess cyclic shear resistance of soil from laboratory element tests

2016 ◽  
Vol 53 (9) ◽  
pp. 1460-1473 ◽  
Author(s):  
Dharma Wijewickreme ◽  
Achala Soysa
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Shear Stiffness ◽  
Large Strains ◽  
Fundamental Parameter ◽  
Stress Strain ◽  
Cyclic Shear ◽  
Excess Pore Water Pressure ◽  
Excess Pore

The cyclic shear response of soils is commonly examined using undrained (or constant-volume) laboratory element tests conducted using triaxial and direct simple shear (DSS) devices. The cyclic resistance ratio (CRR) from these tests is expressed in terms of the number of cycles of loading to reach unacceptable performance that is defined in terms of the attainment of a certain excess pore-water pressure and (or) strain level. While strain accumulation is generally commensurate with excess pore-water pressure, the definition of unacceptable performance in laboratory tests based purely on cyclic strain criteria is not robust. The shear stiffness is a more fundamental parameter in describing engineering performance than the excess pore-water pressure alone or shear strain alone; so far, no criterion has considered shear stiffness to determine CRR. Data from cyclic DSS tests indicate consistent differences inherent in the patterns between the stress–strain loops at initial and later stages of cyclic loading; instead of relatively “smooth” stress–strain loops in the initial parts of loading, nonsmooth changes in incremental stiffness showing “kinks” are notable in the stress–strain loops at large strains. The point of pattern change in a stress–strain loop provides a meaningful basis to determine the CRR (based on unacceptable performance) in cyclic shear tests.

Consolidation Theory for Composite Ground with Granular Columns Based on Different Calculation Models

2011 ◽  
Vol 261-263 ◽  
pp. 1534-1538
Author(s):  
Yu Guo Zhang ◽  
Ya Dong Bian ◽  
Kang He Xie
Keyword(s):  
Pore Water ◽  
Analytical Solutions ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Vertical Flow ◽  
Excess Pore Water Pressure ◽  
Consolidation Theory ◽  
Composite Ground ◽  
Granular Column ◽  
Excess Pore

The consolidation of the composite ground under non-uniformly distributed initial excess pore water pressure along depth was studied in two models which respectively considering both the radial and vertical flows in granular column and the vertical flow only in granular column, and the corresponding analytical solutions of the two models were presented and compared with each other. It shows that the distribution of initial excess pore water pressure has obvious influence on the consolidation of the composite ground with single drainage boundary, and the rate of consolidation considering the radial-vertical flow in granular column is faster than that considering the vertical flow only in granular column.

Sign in / Sign up

Export Citation Format

Share Document