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Foundation analysis and design
01 Jan 1968-
TL;DR: In this paper, Fondation de soutenagement et al. presented a reference record for Dimensionnement Reference Record created on 2004-09-07, modified on 2016-08-08.
Abstract: Keywords: Fondation ; Mur de soutenement ; Pieux ; Capacite portante ; Ancrage ; Dimensionnement Reference Record created on 2004-09-07, modified on 2016-08-08
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TL;DR: In this article, a relatively simple work hardening/softening soil constitutive model is developed to represent dense frictional soils behavior under different stress levels, based on the accumulation of the plastic work during a simple direct shear test and its relationship to stress ratio.
Abstract: Foundations behavior is affected by soil behavior which can vary from dilative to contractive depending on the stress level, particularly in dense frictional soils. The Zero Extension Lines (ZEL) method has been generally developed to predict the foundations behavior. Knowledge of soil behavior enables the ZEL method to predict the general and local shear failure modes. In this paper, a relatively simple work hardening/softening soil constitutive model is developed to represent dense frictional soils behavior under different stress levels. This model is based on the accumulation of the plastic work during a simple direct shear test and its relationship to stress ratio to establish the hardening law. Verifications have been made for the developed soil model. The model is then implemented into the ZEL method to theoretically investigate the bearing capacity and load-displacement behavior of foundations over dense frictional soils. Utilization of this model enables the ZEL method to capture different modes of failure depending on the foundation size. A numerical study on foundations behavior was performed showing the ability of the presented approach in capturing both failure modes.
4Â citations
TL;DR: In this article, the interference effects on bearing capacity of two and three closely spaced strip footings resting on granular bed overlying clay are studied, and a simple analytical model is proposed to predict the load-carrying capacity and the interference factor of an interfered footing, when adjacent strip feetings are optimally placed on the surface of a Granular Bed (GB) overlying Clay and both the footings are simultaneously loaded.
Abstract: In the present paper, the interference effects on bearing capacity of two and three closely spaced strip footings resting on granular bed overlying clay are being studied. A simple analytical model is proposed to predict the load-carrying capacity and the interference factor of an interfered footing, when adjacent strip footings are optimally placed on the surface of a Granular Bed (GB) overlying clay and both the footings are simultaneously loaded. A punching shear failure mechanism is envisaged in the analytical model. The load-carrying capacity of the footing is taken as the sum of total shearing resistances along the two vertical planes through the edges of the strip footing in the upper granular layer and the load-carrying capacity of the soft clay beneath the GB. Insights gained from finite element simulations are used to develop the new modified punching shear model for interfering footing. Bearing capacity can be easily calculated by using the proposed punching shear model for interfering footing. The analytical model is validated with numerical analyses and previous experimental results and found to be in reasonably good agreement. The influence of different parameters such as granular bed thickness, width of footing, number of footings are carried out in this study. Doi: 10.28991/cej-2021-03091723 Full Text: PDF
4Â citations
TL;DR: In this paper , a new method of characterization of expansive clays after oedometer test results performed on intact saturated clay specimens was introduced, where a novel mitigation solution reduced the swelling effect by placing a compacted granular layer as an interface between the expansive clay and the foundation.
Abstract: This article first introduces a new method of characterization of expansive clays after oedometer test results performed on intact saturated clay specimens. On the presumed expansive clays specimens, oedometer tests are preceded by the free swelling test from which the swelling pressure is measured. From current oedometer test results carried out on expansive and non-expansive clays, the ratio of compression index (Cc) by the swelling index (Cs) was determined. A threshold value of the ratio Cc/Cs was identified to distinguish between expansive clay specimens and non-expansive clay specimens. Second, a novel mitigation method of the swelling phenomena was validated by performing oedometer tests on expansive clay specimens preceding the measurement of swelling pressure. Oedometer tests performed on a 53% thickness clay specimen overlaid by a 47% thickness of sand showed a significant reduction of the swelling pressure compared to that measured on a full expansive clay specimen. The mitigation solution reduced the swelling effect by placing a compacted granular layer as an interface between the expansive clay and the foundation. This solution has been adopted and approved in forthcoming a lightweight building construction at the Faculty of Sciences of Tunis City.
4Â citations
01 Jan 1991
TL;DR: Cracking parallel to the highway alignment (longitudinal cracking) was discovered in flexible pavement constructed over high-PI clay embankments retained by reinforced soil retaining walls (RSRWs).
Abstract: Cracking parallel to the highway alignment (longitudinal cracking) was discovered In flexible pavement constructed over high-PI clay embankments retained by reinforced soil retaining walls (RSRWs) The cracks were noted to occur at approximately the location of the Interface between the clay embankment and the cohesionless backfill of the RSRW Coring of the crack revealed the crack to be wider at the bottom than at the top suggesting that the tensile force causing the cracking was being applied at the bottom of the pavement structure All Texas State Dept of Highways and Public Transportation (SDHPT) Districts were queried to learn the extent of the longitudinal cracking problem Only District 16, head- quartered at Corpus Christi, was found to be experiencing the problem Using soil from the same source as was used to construct embankments and RSRW backfill, four large laboratory models were constructed of the field situation Each of the tests demonstrated that a vertical separation would occur between the clay embankment and sand backfill as a result of lateral shrinking of the high-PI clay over time due to climate The third test showed that the vertical crack would propagate upwards through the flexible base material The fourth test produced a crack through the flexible base but failed to produce a crack through the overlying HMAC because the HMAC adhered to the walls of the test box and separated from the caliche base Lateral stresses imposed on the flexible base by the laterally shrinking clay embankment were found to be approximately 366 psi in the laboratory tests, well exceeding the tensile strength of normal HMAC Thus, it was concluded that the longitudinal cracks observed In the District 16 pavements constructed over high-Pi clay embankments retained by reinforced earth retaining walls were the result of the clay embankments laterally drying beneath the Installed pavement Field Instrumentation Installed during the study was inconclusive with respect to measuring soil moisture condition changes occurring beneath the pavement because the monitoring sites were not paved until nearly the end of the study However, the Instruments showed that a change in soil suction pressures of up to 25 atmospheres of pressure had occurred during the 1-year monitoring period as a result of changes in climate only Four recommendations for dealing with the problem were made for those instances when high-Pi clay material cannot be avoided in constructing reinforced earth retained embankments: (1) construct a zone of mixed soil with a lower Pi across the clay-sand interface; (2) construct a sand subbase between the clay subgrade and the flexible pavement base; (3) permit the crack to occur, repair the crack, and apply a final lift of HMAC; and (4) spray cut-back asphalt to encapsulate the clay embankment and prevent any change in soil moisture conditions
4Â citations
01 Apr 2010
TL;DR: In this article, a 2D approximation of a potash mine using a plane strain idealization for mine depths of 304.8 m (1000 ft) and 609.6 m (2000 ft) is presented.
Abstract: Geomechanical analyses have been performed to investigate potential mine interactions with wellbores that could occur in the Potash Enclave of Southeastern New Mexico. Two basic models were used in the study; (1) a global model that simulates the mechanics associated with mining and subsidence and (2) a wellbore model that examines the resulting interaction impacts on the wellbore casing. The first model is a 2D approximation of a potash mine using a plane strain idealization for mine depths of 304.8 m (1000 ft) and 609.6 m (2000 ft). A 3D wellbore model then considers the impact of bedding plane slippage across single and double cased wells cemented through the Salado formation. The wellbore model establishes allowable slippage to prevent casing yield.
4Â citations