Compression and strength of dense sand at high pressures and elevated temperatures

2004 ◽  
Vol 41 (6) ◽  
pp. 1206-1212 ◽  
Author(s):  
James Graham ◽  
Marolo Alfaro ◽  
Gerald Ferris
Keyword(s):  
High Pressures ◽  
Elevated Temperatures ◽  
Confining Pressure ◽  
Triaxial Tests ◽  
One Dimensional ◽  
Dense Sand ◽  
Strain Behaviour ◽  
Effects Of Temperature ◽  
Canada Limited ◽  
Compression Shear Strength

The paper examines the stress–strain behaviour of densely compacted sand tested at pressures up to 80 MPa in one-dimensional compression and 7.2 MPa confining pressure in triaxial tests. Tests were performed at temperatures up to 100 °C. The testing relates to a proposal by Atomic Energy of Canada Limited to fill containers of waste nuclear fuel with a crushed quartz sand to provide additional stiffness. No significant effects of temperature were encountered in either isotropic compression or triaxial shear.Key words: sand, compression, shear strength, temperature, pressure.

A Comparative Study Between Lateral and Upward Anchor-Soil and Pipe-Soil Interaction in Dense Sand

2016 ◽  
Author(s):  
Kshama Roy ◽  
Bipul Hawlader ◽  
Shawn Kenny ◽  
Ian Moore
Keyword(s):  
Shear Bands ◽  
Experimental Studies ◽  
Confining Pressure ◽  
Design Guidelines ◽  
Vertical Strip ◽  
Dense Sand ◽  
Progressive Development ◽  
Lateral Resistance ◽  
Strain Behaviour ◽  
Uplift Forces

Buried pipelines are extensively used in onshore and offshore environments for transportation of hydrocarbons. On the other hand, buried anchors have been used for many years to stabilize various structures. In the development of design guidelines for pipelines, theoretical and experimental studies on buried anchors are sometimes used assuming that pipeline-soil and anchor-soil interaction are similar. In the present study, finite element (FE) modeling is performed to simulate the response of pipeline and anchor buried in dense sand subjected to lateral and uplift forces. The similarities and differences between the responses of these two types of structures are examined to justify the application of anchor theory to pipeline behaviour. The stress-strain behaviour of dense sand is modeled using a Modified Mohr-Coulomb (MMC) model, which considers the pre-peak hardening, post-peak softening, density and confining pressure dependent friction and dilation angles. A considerable difference is found between the lateral resistance of pipeline and vertical strip anchor of similar size. Progressive development of shear bands (shear strain concentrated zone) can explain the load-displacement behaviour for both lateral and upward loading.

The mechanical behavior of Anvil Points oil shale at elevated temperatures and confining pressures

1983 ◽  
Vol 20 (2) ◽  
pp. 344-352 ◽  
Author(s):  
David H. Zeuch
Keyword(s):  
Compressive Strength ◽  
Oil Shale ◽  
Elevated Temperatures ◽  
Constant Strain Rate ◽  
Confining Pressure ◽  
Compression Tests ◽  
Confining Pressures ◽  
Strain Rate Compression ◽  
Effects Of Temperature ◽  
Good Agreement

Twenty-one constant-strain-rate compression tests have been performed on 80 mL/kg (20 gallons/ton) Anvil Points oil shale at elevated temperatures (50–200 °C) and confining pressures (0.5–40 MPa). The strength of oil shale increases approximately linearly with confining pressure and decreases nonlinearly with temperature. Ductility is greatly enhanced by the application of confining pressure. Elevated temperatures have little influence on ductility at low confining pressures; however, temperature exerts a progressively more pronounced influence on ductility with increasing confining pressure. A purely empirical failure law, incorporating the effects of temperature and confining pressure, has been fitted to the data. The failure law is in good agreement with the results of other studies on the compressive strength of oil shale. Keywords: oil shale, strength–temperature–pressure behaviour, rock mechanics, kerogen.

Stress–strain behaviour of weathered weak rock in middle-sized triaxial tests

2006 ◽  
Vol 43 (10) ◽  
pp. 1096-1104 ◽  
Author(s):  
De'an Sun ◽  
Tugen Feng ◽  
Hajime Matsuoka
Keyword(s):  
Triaxial Test ◽  
Confining Pressure ◽  
Triaxial Tests ◽  
Weak Rock ◽  
Test Results ◽  
Compression Tests ◽  
Stress Strain ◽  
Strain Behaviour ◽  
Undisturbed Samples ◽  
Strain Relationship

A middle-sized triaxial test apparatus for a specimen 20 cm in height and 10 cm in diameter was developed to measure the deformation and strength of weak rock or gravel. High-quality undisturbed samples of a weathered weak rock were taken from a dam site by a core drilling method. To avoid damage to the structure of the weak rock due to saturation of specimens as a result of measuring volume change through the water change in a burette, the lateral deformation of specimens was directly measured in the unsaturated condition using three rings mounted on the specimen. Using the developed triaxial test apparatus, isotropic compression tests and consolidated–drained triaxial compression tests were performed on unsaturated or saturated undisturbed samples under confining pressures of 49, 98, 196, 392, 539, and 683 kPa. The test results show that the stress–strain relationship of the weathered weak rock under both unsaturated and saturated conditions is strongly influenced by the confining pressure when the confining pressure is less than 392 kPa, and the stress–strain behaviour becomes similar to that of normally consolidated clay when the confining pressure is greater than 392 kPa. Comparison of results of triaxial tests on unsaturated and saturated specimens shows that the saturated samples become somewhat weak. The test results also show that the bonding and stress history largely influence the stress–strain relationship at small strain levels.Key words: weathered weak rock, microstructure, undisturbed sample, deformation, strength, triaxial test, unsaturated sample.

Influences of Strain-Rate and Stress-State on Dynamic Response of Cement Mortar

2003 ◽  
Vol 03 (03) ◽  
pp. 419-433 ◽  
Author(s):  
L.-L. Wang ◽  
S.-Q. Shi ◽  
J.-Y. Chen ◽  
D.-J. Huang ◽  
L.-J. Shen
Keyword(s):  
Stress State ◽  
Dynamic Response ◽  
Strain State ◽  
High Pressures ◽  
Cement Mortar ◽  
Heterogeneous Material ◽  
Confining Pressure ◽  
Internal Damage ◽  
One Dimensional ◽  
Rate Dependent

At high strain rates, the dynamic response of cement mortar, a heterogeneous material with damage, was experimentally studied under three different stress states: (1) one-dimensional stress state by using the SHPB technique, (2) one-dimensional strain state at high pressures from 1 to 5 GPa by using a one-stage gas gun, and (3) quasi one-dimensional strain state by using an improved passive confining SHPB technique. The experimental results indicate that cement mortar is a kind of nonlinear rate-dependent material with internal damage evolution, and that the confining pressure greatly influences its ductility and strength. The main results are given and discussed.

An experimental examination of the critical state and other similar concepts for granular soils

1995 ◽  
Vol 32 (6) ◽  
pp. 1065-1075 ◽  
Author(s):  
J. Chu
Keyword(s):  
Critical State ◽  
Friction Angle ◽  
Stress Path ◽  
Dense Medium ◽  
Triaxial Tests ◽  
Granular Soils ◽  
Test Results ◽  
Dense Sand ◽  
Strain Behaviour ◽  
Series Of Experiments

Measuring the critical state parameters of dense granular soil by drained triaxial tests is problematic, as significant nonhomogeneous deformations can develop prior to approaching a critical state. This leads to further questions on the verification of the critical state concept for granular soils. In this study a new testing method, which enables the critical state of dense sand to be measured in the homogeneous deformation region, was adopted to measure the critical state of dense sand and to examine the critical state concept. A series of experiments was carried out to measure the critical state for dense, medium dense, and loose sand. The test results show that although a unique critical state curve may exist, the critical state friction angle is not constant but stress level dependent. The other similar concepts, namely, the phase transformation state, the characteristic state, and the steady state, were also examined, and the relationships among these states were established. Key words : critical state, granular soils, stress path, stress–strain behaviour, triaxial test.

Effects of Stress Path and Stress History on the Stiffness of Reconstituted London Clay

1986 ◽  
Vol 2 (1) ◽  
pp. 139-144 ◽  
Author(s):  
J. H. Atkinson ◽  
J. S. Evans ◽  
D. Richardson
Keyword(s):  
Stress Path ◽  
Triaxial Tests ◽  
Soil Parameters ◽  
Stress History ◽  
Strain Behaviour ◽  
Reconstituted Soil ◽  
Path Dependent ◽  
London Clay ◽  
Soil Behaviour

AbstractSoil behaviour is stress history dependent and stress path dependent and soil parameters, particularly those for stress-strain behaviour, measured in conventional triaxial tests may not represent the behaviour of soil in many civil engineering works.To obtain more realistic parameters it may be necessary to conduct laboratory tests which more closely represent in situ conditions before and during construction.The paper describes equipment developed at The City University to carry out stress path tests simply and economically. A series of CU triaxial tests and stress path tests on reconstituted soil illustrate the dependence of measured soil parameters on stress history and stress path.

Drained instability of sand in plane strain

2010 ◽  
Vol 47 (4) ◽  
pp. 400-412 ◽  
Author(s):  
Dariusz Wanatowski ◽  
Jian Chu ◽  
Wai Lay Loke
Keyword(s):  
Experimental Data ◽  
Plane Strain ◽  
Case Studies ◽  
Static Loading ◽  
State Parameter ◽  
Dam Failure ◽  
Triaxial Tests ◽  
Granular Soil ◽  
Laboratory Studies ◽  
Dense Sand

Flowslide or failure of loose granular soil slopes is often explained using liquefaction or instability data obtained from undrained triaxial tests. However, under static loading conditions, the assumption of an undrained condition is not realistic for sand, particularly clean sand. Case studies have indicated that instability of granular soil can occur under essentially drained conditions (e.g., the Wachusett Dam failure in 1907). Laboratory studies on Changi sand by Chu et al. in 2003 have shown that sand can become unstable under completely drained conditions. However, these studies were carried out under axisymmetric conditions and thus, cannot be applied directly to the analysis of slope failures. In this paper, experimental data obtained from plane-strain tests are presented to study the instability behaviour of loose and dense sand under plane-strain conditions. Based on these test data, the conditions for the occurrence of drained instability in plane strain are established. Using the modified state parameter, the conditions for instability under both axisymmetric and plane-strain conditions can be unified. A framework for interpreting the instability conditions of sandy slopes developed under axisymmetric conditions also extends into plane-strain conditions.

Study on the Dynamic Performance of Asphalt Concrete under Passive Confined Pressure

2012 ◽  
Vol 226-228 ◽  
pp. 1755-1759
Author(s):  
Hua Zhang ◽  
Fei Li ◽  
Yu Wei Gao
Keyword(s):  
Elastic Modulus ◽  
Asphalt Concrete ◽  
Poisson Ratio ◽  
Dynamic Properties ◽  
Dynamic Performance ◽  
Dynamic Strength ◽  
Confining Pressure ◽  
Mechanical Behaviors ◽  
One Dimensional ◽  
Stress States

An improved passive confining pressure SHPB method was used to study the dynamic mechanical behaviors of asphalt concrete under quasi-one dimensional strain state. The effect of confining jacket material and its geometrical sizes on the confining pressure were discussed. The dynamic strength, dynamic modulus of elasticity and dynamic Poisson ratio of asphalt concrete were obtained. The influential rules of confining pressure on the dynamic properties were studied by comparing the stress-strain curves of asphalt concrete under different stress states. The study found that passive confining greater impact on the strength of asphalt concrete than elastic modulus and Poisson ratio, but the elastic modulus improved with the increase of confining pressure.

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