Application of an effective stress design method to concrete piles driven in Mexico City clay

2005 ◽  
Vol 42 (6) ◽  
pp. 1495-1508 ◽  
Author(s):  
Emilio E Saldivar ◽  
Richard J Jardine
Keyword(s):  
Mexico City ◽  
Effective Stress ◽  
Design Method ◽  
Friction Angle ◽  
Unit Weight ◽  
Silty Clay ◽  
Concrete Piles ◽  
Clay Deposits ◽  
Ground Conditions ◽  
Pile Load Tests

Piled foundations are used widely in the lake clay zones of Mexico City, with “friction” piles being driven into soft diatomaceous clay deposits that show an extraordinary range of mechanical properties. The paper assesses the applicability of the Imperial College pile (ICP) design method to the concrete piles driven in these deposits. After the ICP methodology and Mexico City ground conditions are reviewed, an experimental study is reported of the key soil properties required for the ICP procedures: yield stress ratio, unit weight, interface friction angle (δ), sensitivity (St), and intrinsic properties. The new data are then applied to a specially assembled database of static pile load tests from different Mexico City clay locations, with allowance being made for site-specific details and local installation procedures. A quantitative assessment shows that the ICP methodology is free from significant bias and leads to more reliable estimates of static capacity than the total stress (α) design method routinely used in Mexico City.Key words: validation, database, static axial pile capacity, driven friction pile, effective stress design, silty clay.

scholarly journals Study on Water Characteristic Curve and Shear Characteristics of Typical Unsaturated Silty Clay in Shaoxing

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Ruiqian Wu ◽  
Youzhi Tang ◽  
Shaohe Li ◽  
Wei Wang ◽  
Ping Jiang ◽  
...  
Keyword(s):  
Shear Strength ◽  
Internal Friction ◽  
Unsaturated Soil ◽  
Direct Shear Test ◽  
Shear Test ◽  
Characteristic Curve ◽  
Friction Angle ◽  
Matric Suction ◽  
Silty Clay ◽  
Direct Shear

In order to probe into one simplified method to predict the shear strength of Shaoxing unsaturated silty clay, the test method combining unsaturated soil consolidation instrument and conventional direct shear instrument is used to study the shear strength, and the method is compared and verified with the results of equal suction direct shear test. The research results show that the soil water characteristic curve fitted by the measured data points and VG model has obvious stage characteristics in the range of 0~38 kPa, 38~910 kPa, and 910~10000 kPa. The shear strength of unsaturated soil measured by consolidation meter combined with conventional direct shear test is in good agreement with that measured by equal suction direct shear test in the range of 0~500 kPa. The results show that the shear strength, total cohesion, and effective internal friction angle of soil increase slightly with the increase of matric suction in the range of 0~38 kPa. When the matric suction increases from 38 kPa to 500 kPa, the shear strength and total cohesion force of the soil have similar stage characteristics with the SWCC, which first increases and then tends to be stable, while the effective internal friction angle changes slightly. Finally, taking the air-entry value as the demarcation point, an improved model of unsaturated shear strength is proposed by analyzing the error value. Compared with the measured value, the absolute value of relative error is basically kept in the range of 5%~10%, which is close to the measured value.

scholarly journals Sensitivity Analysis of Influencing Factors of Building Slope Stability Based on Orthogonal Design and Finite Element Calculation

2018 ◽  
Vol 53 ◽  
pp. 03076
Author(s):  
RUAN Jin-kui ◽  
ZHU Wei-wei
Keyword(s):  
Finite Element ◽  
Slope Stability ◽  
Design Method ◽  
Orthogonal Design ◽  
Slope Angle ◽  
Friction Angle ◽  
Range Analysis ◽  
Factors Affecting ◽  
Orthogonal Test Design ◽  
The Stability

In order to study the sensitivity of factors affecting the homogeneous building slope stability, the orthogonal test design method and shear strength reduction finite element method were used. The stability safety factor of the slope was used as the analysis index, and the range analysis of results of 18 cases were carried out. The results show that the order of sensitivity of slope stability factors is: internal friction angle, slope height, cohesion, slope angle, bulk density, elastic modulus, Poisson's ratio. The analysis results have reference significance for the design and construction of building slope projects.

Study of Correlation on Unconfined Compressive Strength between Different Soil

2013 ◽  
Vol 838-841 ◽  
pp. 926-929
Author(s):  
Xia Zhao
Keyword(s):  
Compressive Strength ◽  
Soil Moisture ◽  
Moisture Content ◽  
Unconfined Compressive Strength ◽  
Laboratory Tests ◽  
Soil Moisture Content ◽  
Correlation Coefficients ◽  
Friction Angle ◽  
Silty Clay ◽  
Soil Cohesion

Take the silty clay and clay as the research object, the correlation between bulk density, moisture content, cohesion, friction angle and unconfined compressive strength was analyzed using laboratory tests, and the results showed that soil cohesion, friction angle and unconfined compressive strength with good correlation, the correlation coefficients were all above 0.9, while severe and soil moisture content and unconfined compressive strength of correlation is weak, followed by the correlation formulas of the index and unconfined compressive strength were established, these formulas can used to predict the unconfined compressive strength of soil.

Grey Correlation Analysis on the Sensitive Factors of Plastic Zone Extension of Surrounding Rock

2013 ◽  
Vol 438-439 ◽  
pp. 1210-1216
Author(s):  
Xuan Rong Zheng
Keyword(s):  
Correlation Analysis ◽  
Plastic Zone ◽  
Deformation Modulus ◽  
Friction Angle ◽  
Surrounding Rock ◽  
Unit Weight ◽  
Analysis Method ◽  
Grey Correlation ◽  
Grey Correlation Analysis ◽  
Ground Stress

As lack of explicit analysis method on the sequence of many factors influencing the plastic zone extension of surrounding rock, the grey correlation analysis method is adopted to study the relationship between the plastic zone extension radius Rp and the six factors such as cohesive c, internal friction angle φ, deformation modulus E, unit weight γ, initial ground stress σ and the radius of chamber r. By dealing with dimensionless, the corresponding sequences composed with the sensitive factors as sub-sequence and the plastic zone extension radius as mother sequence are obtained. The gray correlation analysis model of sensitive factors which evaluates the results with grey correlation degree is built by the methods of dimensionless and extreme difference variation. Then, an engineering example is analyzed with grey correlation. Based on the analysis results, the sorting of sensitive factors is φ > σ > c > r > E > γ. It implies that the influences of internal friction angle φ and initial ground stress σ are the most prominent, and the sensitivities of deformation modulus E and unit weight γ are lowest. These are in good agreement with the analytical formula of classical theory, and can be used in guiding the further optimization and improvement of the analytical expression of the plastic zone extension radius Rp of surrounding rock.

scholarly journals Slope stability analysis in the case of probabilistic and semi-probabilistic design method

2019 ◽  
Vol 97 ◽  
pp. 04044
Author(s):  
Hubert Szabowicz
Keyword(s):  
Finite Element ◽  
Internal Friction ◽  
Design Method ◽  
Probability Distributions ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Probabilistic Modelling ◽  
Finite Element Software ◽  
Random Finite Element Method ◽  
Slope Factor

This paper addresses the issue of probabilistic and semi-probabilistic modelling of soil slopes. A slope made of cohesive-frictional soil of specific geometry was analysed as an example. Results were calculated for two methods using the Z-Soil finite element software. It has been assumed that the probability distributions of strength parameters, cohesion and internal friction angle are normal distributions with average values and coefficient of variation = 0.2. Random finite element method (RFEM) has been used for probabilistic modelling. Random fields of cohesion and internal friction angle have been generated using the Fourier series method (FSM). Monte Carlo simulation has been used to calculate the statistics of the slope factor of safety in order to determine the probability of failure. Moreover, assumed parameter distributions allowed to determine safe characteristic values used in the semi-probabilistic partial factors method. Both approaches have been compared in the article.

scholarly journals Bearing Capacity of Ring Foundations on Sand Overlying Clay

2020 ◽  
Vol 10 (13) ◽  
pp. 4675
Author(s):  
Chaowei Yang ◽  
Zhiren Zhu ◽  
Yao Xiao
Keyword(s):  
Bearing Capacity ◽  
Friction Angle ◽  
Failure Criteria ◽  
Unit Weight ◽  
Sand Layer ◽  
Collapse Mechanisms ◽  
Internal Radius ◽  
Vertical Bearing ◽  
Vertical Bearing Capacity ◽  
Ring Foundations

The vertical bearing capacity of rough ring foundations resting on a sand layer overlying clay soil is computed in this study by using finite element limit analysis (FELA). The sands and clays are assumed as elastoplastic models, obeying Mohr–Coulomb and Tresca failure criteria, respectively. Based on the FELA results, design charts are provided for evaluating the ultimate bearing capacity of ring foundations, which is related to the undrained shear strength of the clay, the thickness, the internal friction angle, the unit weight of the sand layer, and the ratio of the internal radius to the external radius of the footing. A certain thickness, beyond which the clay layer has a negligible effect on the bearing capacity, is determined. The collapse mechanisms are also examined and discussed.

Formulation of Seismic Passive Resistance of Retaining Wall Backfilled with c-F Soil

2012 ◽  
Vol 3 (2) ◽  
pp. 15-24 ◽  
Author(s):  
Sima Ghosh
Keyword(s):  
Retaining Wall ◽  
Pressure Coefficient ◽  
Earth Pressure ◽  
Friction Angle ◽  
Wall Friction ◽  
Unit Weight ◽  
Passive Resistance ◽  
Angle Of Internal Friction ◽  
Variation Of Parameters ◽  
Wide Range

Knowledge of passive resistance is extremely important and it is the basic data required for the design of geotechnical structures like the retaining wall moving towards the backfill, the foundations, the anchors etc. An attempt is made to develop a formulation for the evolution of seismic passive resistance of a retaining wall supporting c-F backfill using pseudo-static method. Considering a planar rupture surface, the formulation is developed in such a way so that a single critical wedge surface is generated. The variation of seismic passive earth pressure coefficient are studied for wide range of variation of parameters like angle of internal friction, angle of wall friction, cohesion, adhesion, surcharge, unit weight of the backfill material, height and seismic coefficients.

scholarly journals Mapping the susceptibility of rain-triggered lahars at Vulcano island (Italy) combining field characterization, geotechnical analysis, and numerical modelling

2019 ◽  
Vol 19 (11) ◽  
pp. 2421-2449 ◽  
Author(s):  
Valérie Baumann ◽  
Costanza Bonadonna ◽  
Sabatino Cuomo ◽  
Mariagiovanna Moscariello ◽  
Sebastien Biass ◽  
...  
Keyword(s):  
Hydraulic Conductivity ◽  
Slope Angle ◽  
Field Measurements ◽  
Friction Angle ◽  
Unit Weight ◽  
Residual Water ◽  
Probabilistic Modelling ◽  
Cascading Effect ◽  
Geotechnical Tests ◽  
Tephra Fallout

Abstract. The characterization of triggering dynamics and remobilized volumes is crucial to the assessment of associated lahar hazards. We propose an innovative treatment of the cascading effect between tephra fallout and lahar hazards based on probabilistic modelling that also accounts for a detailed description of source sediments. As an example, we have estimated the volumes of tephra fallout deposit that could be remobilized by rainfall-triggered lahars in association with two eruptive scenarios that have characterized the activity of the La Fossa cone (Vulcano, Italy) in the last 1000 years: a long-lasting Vulcanian cycle and a subplinian eruption. The spatial distribution and volume of deposits that could potentially trigger lahars were analysed based on a combination of tephra fallout probabilistic modelling (with TEPHRA2), slope-stability modelling (with TRIGRS), field observations, and geotechnical tests. Model input data were obtained from both geotechnical tests and field measurements (e.g. hydraulic conductivity, friction angle, cohesion, total unit weight of the soil, and saturated and residual water content). TRIGRS simulations show how shallow landsliding is an effective process for eroding pyroclastic deposits on Vulcano. Nonetheless, the remobilized volumes and the deposit thickness threshold for lahar initiation strongly depend on slope angle, rainfall intensity, grain size, friction angle, hydraulic conductivity, and the cohesion of the source deposit.

The Choice of Basic Pillar Design Theory for Locked Sand Condition

2012 ◽  
Vol 256-259 ◽  
pp. 354-357
Author(s):  
Zi Wei Ding ◽  
Amirhossein Bagherieh ◽  
Rui Min Feng ◽  
Xing Xing Wen
Keyword(s):  
Design Theory ◽  
Design Method ◽  
Friction Angle ◽  
Confining Pressure ◽  
Triaxial Tests ◽  
Pillar Design ◽  
Design Theories ◽  
Locked Sand ◽  
Unconfined Strength ◽  
Very High

Because of unique properties of locked sand (very high friction angle and very low cohesion), a new pillar design method based on present basic pillar design theories must be developed. Wilson theory puts its focus on confining pressure, which is related to friction angle and cohesion. Triaxial tests results show that locked sand at Pattison mine has an average friction angle of 57°, which means the strength of the material increases rapidly with the confining pressure, and average cohesion of 2.6 MPa. Results show that choosing Wilson theory as basic pillar design theory not only considers the high friction angle of locked sand, but also minimizes the effects of Wilson’s hypothesis of neglecting the unconfined strength.

Sign in / Sign up

Export Citation Format

Share Document