A numerical solution of cavity expansion problem in sand based directly on experimental stress-strain curves

1998 ◽  
Vol 35 (4) ◽  
pp. 541-559 ◽  
Author(s):  
Branko Ladanyi ◽  
Adolfo Foriero
Keyword(s):  
Numerical Solution ◽  
Strain Path ◽  
Shear Resistance ◽  
Cavity Expansion ◽  
Large Strains ◽  
Volume Changes ◽  
Stress Strain ◽  
Stress Variation ◽  
Cylindrical Cavity Expansion ◽  
State Of Stress

A numerical solution of a spherical and cylindrical cavity expansion problem in sand is presented herein. The underlying theory is unbiased in that it is based directly on experimentally determined stress-strain curves. The solution makes it possible to follow the continuous variation of strains, stresses, and volume changes produced by cavity expansion. It essentially uses the "strain path" approach to determine the state of stress around the cavity, taking into account large strains and the effect of spherical stress variation on the mobilized shear resistance and the associated volume strains. A limited comparison with experimental data shows a reasonable agreement between theory and measurements.Key words: cavities, expansion, sand, stress-strain curves, numerical solution.

The Influence of State of Stress on the Stress-Strain Behavior of Rocks

1972 ◽  
Vol 94 (1) ◽  
pp. 238-242 ◽  
Author(s):  
S. R. Swanson ◽  
W. S. Brown
Keyword(s):  
Experimental Investigation ◽  
Strain Response ◽  
Volume Changes ◽  
Stress Strain ◽  
Strain Behavior ◽  
Permanent Set ◽  
State Of Stress

An experimental investigation of the stress-strain behavior of several rocks is described. The stress-strain response of the rocks tested is seen to be quite complicated, exhibiting a number of inelastic effects even in rocks considered brittle under pressure. The inelasticity is manifested in permanent set and hysteresis on unloading and volume changes produced by shearing stresses.

Strain-rate effects in pressuremeter testing using a cuboidal shear device: experiments and modeling

1998 ◽  
Vol 35 (1) ◽  
pp. 27-42 ◽  
Author(s):  
Dayakar Penumadu ◽  
Arumugam Skandarajah ◽  
Jean-Lou Chameau
Keyword(s):  
Shear Strength ◽  
Strain Rate ◽  
Strain Path ◽  
Undrained Shear Strength ◽  
Cavity Expansion ◽  
Lateral Strain ◽  
High Water Content ◽  
Single Element ◽  
Stress Strain ◽  
Undrained Shear

The objective of the present research was to study the effect of rate of probe expansion in pressuremeter testing for cohesive soil. Emphasis in this paper was given to quantifying and modeling the effect of strain rate on the undrained shear strength. The strain path followed by an element of clay adjacent to the expanding probe was simulated using an automated flexible boundary cuboidal shear device (CSD) typically up to a magnitude of strain level of 10%. Two types of soil (kaolin, kaolin-silica mix) were used consistently for all the testing. Repeatable cubical cohesive specimens were obtained from a high water content slurry consolidation technique. K0 consolidation was performed by using a constant vertical stress - zero lateral strain boundary condition using a closed-loop pneumatic system. A series of strain-controlled tests with increasing strain rates from 0.01 to 5%/min was performed under undrained conditions. The effects of increase of strain rate on shear stress - strain behavior and undrained shear strength were quantified. A numerical model based on cylindrical cavity expansion theory which accounts for higher strain rate and its variation with radial distance from an expanding probe membrane was calibrated using the single-element CSD test data.Key words: strain rate, pressuremeter, stress-strain, shear strength, strain path, cavity expansion.

Effects of sample disturbance and consolidation procedures on measured shear strength of soft marine Norwegian clays

2006 ◽  
Vol 43 (7) ◽  
pp. 726-750 ◽  
Author(s):  
Tom Lunne ◽  
Toralv Berre ◽  
Knut H Andersen ◽  
Stein Strandvik ◽  
Morten Sjursen
Keyword(s):  
Shear Stress ◽  
Shear Resistance ◽  
Engineering Properties ◽  
Large Strains ◽  
Stress Strain ◽  
Soft Clays ◽  
Effective Stresses ◽  
Small Strains ◽  
Sample Disturbance

After many decades of research, the issue of sample disturbance is still important as regards to determining reliable and representative soil parameters for foundation design in soft clays. Parallel laboratory tests have been carried out on high-quality block samples and ordinary piston tube samples from 12 deposits of soft Norwegian marine clays. Undrained triaxial and direct simple shear (DSS) tests on samples reconsolidated to the in situ effective stresses show that sample disturbance has a significant effect on the measured stress–strain–strength behaviour: the more disturbed the sample, the lower the shear stress at small strains and the higher the shear stress at large strains. Breakdown of the clay structure, including cementation bonds, is the assumed cause of lower shear resistance at small strains, whereas at large strains the shear resistance is governed mainly by the water content, which for soft clay samples, reconsolidated to the in situ effective stresses, will be lower, and the strength thereby higher, the more disturbed the sample. The work described herein also includes the effects of the consolidation procedure; in addition to the reconsolidation technique, both stress history and normalized soil engineering properties (SHANSEP) and delayed consolidation tests have been carried out.Key words: soft clays, sample disturbance, consolidation procedures, stress–strain–strength behaviour, stress–strain–time behaviour.

Dynamic finite cylindrical cavity-expansion models for cellular steel tube confined concrete targets normally impacted by rigid sharp-nosed projectiles

2021 ◽  
pp. 204141962110272
Author(s):  
Chaomei Meng ◽  
Dianyi Song ◽  
Qinghua Tan ◽  
Zhigang Jiang ◽  
Liangcai Cai ◽  
...  
Keyword(s):  
Cylindrical Cavity ◽  
Approximate Model ◽  
Steel Tube ◽  
Confinement Effect ◽  
Confined Concrete ◽  
Cavity Expansion ◽  
Depth Of Penetration ◽  
Cylindrical Cavity Expansion ◽  
Infinite Cylindrical Shell ◽  
Response Modes

Cellular steel-tube-confined concrete (CSTCC) targets show improved anti-penetration performance over single-cell STCC targets due to the confinement effect of surrounding cells on the impacted cell. Dynamic finite cylindrical cavity-expansion (FCCE) models including radial confinement effect were developed to predict the depth of penetration (DOP) for CSTCC targets normally penetrated by rigid sharp-nosed projectiles, and stiffness of radial confinement was achieved with the elastic solution of infinite cylindrical shell in Winkler medium. Steady responses of dynamic FCCE models were obtained on the assumption of incompressibility of concrete, failure of comminuted zone with Heok–Brown criterion and two possible response modes of the confined concrete in the impacted cell. Furthermore, a DOP model for CSTCC targets normally impacted by rigid projectiles was also proposed on the basis of the dynamic FCCE approximate model. Lastly, relevant penetration tests of CSTCC targets normally penetrated by 12.7 mm armor piecing projectile (APP) were taken as examples to validate the dynamic FCCE models and the corresponding DOP model. The results show that the DOP results based on dynamic FCCE model agree well with those of the CSTCC targets normally penetrated by rigid conical or other sharp-nosed projectiles.

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.

Sign in / Sign up

Export Citation Format

Share Document