Relationship between Shear Wave Velocity and Stresses at Failure for Weakly Cemented Sands During Drained Triaxial Compression

Sharma, Mahesh; Baxter, Christopher; Jander, Michael

doi:10.3208/sandf.51.761

Cited by 28 publications

(9 citation statements)

References 31 publications

(27 reference statements)

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“…The rate of expansion then drops as pronounced shear bands develop. In general, these results are typical of the behavior of artificially cemented specimens prepared with a range of cement types [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37]. Figure 14 shows the response and changes of G max with p′ for typical gypsumcemented samples and comparison with the response for uncemented sand.…”

Section: Gypsum-cemented Sand Resultsmentioning

confidence: 86%

Geomechanical Behavior of Bio-Cemented Sand for Foundation Works

Duraisamy¹,

Airey²

2020

Sandy Materials in Civil Engineering - Usage and Management

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Bio-cementation is an innovative green technology that complements existing ground improvement techniques, but it is yet to be proven for large-scale foundation works. Previously attention has been focused on strategies to inject the bacteria and nutrients to produce the cement in the ground. This study looks at the performance of geomechanical response when the bacteria and nutrients are mixed in sand, an approach that is used in producing cemented soil columns. To explore the mechanical response of bio-cemented soil, results from unconfined compressive strength (UCS) tests and triaxial tests have been analyzed to understand the effects of bio-cementation for sand in contrast to alternative cement, gypsum. The stiffness has also been monitored using bender element techniques in triaxial cell. Both the shear wave signals during the cementation phase and the shearing phase were recorded using this technique. The results show that for a given amount of cement, higher resistances are measured for the bio-cemented samples compared to gypsum. The mixing process is shown to produce homogeneous bio-cemented samples with higher strength and stiffness than the technique of flushing or injection commonly used, provided the amount of calcite is less than 4%. The results show that the bio-cement produces similar mechanical behavior to other artificially cemented sands.

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Section: Gypsum-cemented Sand Resultsmentioning

confidence: 86%

Geomechanical Behavior of Bio-Cemented Sand for Foundation Works

Duraisamy¹,

Airey²

2020

Sandy Materials in Civil Engineering - Usage and Management

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“…Torsional transducers built into the end caps of the triaxial apparatus were used to generate as well as measure the shear waves in the sample (Wang et al 2006). Detailed discussions on shear wave velocity measurement and processing is provided in Sharma et al (2011a).…”

Section: Geophysical Propertiesmentioning

confidence: 99%

Characterization of Weakly Cemented Sands from Geophysical Logs

Sharma

Baxter

2014

Geo-Congress 2014 Technical Papers

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Shear strength is a critical parameter in evaluating the sanding potential of weakly cemented sands in oil bearing formations. The current state-of-the-practice is to use empirical correlations (e.g. relating unconfined compressive strength to velocity logs) developed almost entirely for high strength rocks that grossly overestimate the strength of weakly cemented sands. The objective of this study was to develop a methodology for estimating the strength of weakly cemented sands from commonly measured geophysical logs. An extensive laboratory testing program was first performed on a simulated weakly cemented sand from an oil well. An empirical model was developed that links porosity, horizontal effective stress, and the stresses at failure to synthetic compressional and shear wave velocities calculated using a modified Biot-Gassmann theory. A procedure was then established to infer unconfined compressive strength (q u ), real cohesion (c' r ) and tangential friction angle (ϕ' t ) from the estimated stresses at failure. The model and the procedure was then applied to wireline log data from an oil bearing formation, and there was reasonable agreement between estimated and measured values of strength. This methodology has the potential to estimate strength parameters of weakly cemented oil bearing sand directly from density/porosity logs and compression wave velocity logs.

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“…In order to evaluate such effective elastic properties, the shear wave velocity has been measured through cemented sand samples with different levels of biocalcification …”

Section: Introductionmentioning

confidence: 99%

“…[1][2][3][4] In order to evaluate such effective elastic properties, the shear wave velocity has been measured through cemented sand samples with different levels of biocalcification. [4][5][6][7] The obtained results show a linear relationship between the shear wave velocity and the calcite amount. Al Qabany et al 4 found an increase of the shear velocity V S from 180 m/second for untreated sand to 700 m/second in cemented sand with 5% of calcite in mass, which corresponds to a shear modulus ranging from around 100 to 800 MPa.…”

Section: Introductionmentioning

confidence: 99%

Influence of the microstructural properties of biocemented sand on its mechanical behavior

Dadda

Geindreau

Emeriault

et al. 2018

Num Anal Meth Geomechanics

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Summary The mechanical efficiency of the biocementation process is directly related to the microstructural properties of the biocemented sand, such as the volume fraction of calcite, its distribution within the pore space, coordination number, contact surface area, and types of contact. In the present work, some of these microscopic properties are computed, from 3D images obtained by X‐ray tomography of biocemented sand. These properties are then used as an input in current analytical models to estimate the elastic properties (Young and shear moduli) and the strength properties (Coulomb cohesion). For the elastic properties, the analytical estimates (contact cement theory model) are compared with classical bounds, self‐consistent estimate and numerical results obtained by direct computation (FEM computation) on the same 3D images. Concerning the cohesion, an analytical model initially developed to estimate the cohesion due to suction in unsaturated soils is modified to evaluate the macroscopic cohesion of biocemented sands. Such analytical model is calibrated on experimental data obtained from triaxial tests performed on the same biocemented sand. In overall, the presented results point out the important role of some microstructural parameters, notably those related to the contact, on such effective parameters.

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Relationship between Shear Wave Velocity and Stresses at Failure for Weakly Cemented Sands During Drained Triaxial Compression

Cited by 28 publications

References 31 publications

Geomechanical Behavior of Bio-Cemented Sand for Foundation Works

Geomechanical Behavior of Bio-Cemented Sand for Foundation Works

Characterization of Weakly Cemented Sands from Geophysical Logs

Influence of the microstructural properties of biocemented sand on its mechanical behavior

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