Book•
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 paper, the authors predicted the geological and geotechnical risks of Tabriz Urban Railway Line 2 (TURL2) in Iran, which consists of a 9.5m-diameter, 22km-long tunnel and 20 stations.
Abstract: The essential requirements of a successful tunnel boring machine (TBM) tunnelling operation are complete characterization of the ground and thorough identification of geological and geotechnical risks. This paper predicts the geological and geotechnical risks of Tabriz Urban Railway Line 2 (TURL2) in Iran. The railway consists of a 9.5-m-diameter, 22-km-long tunnel and 20 stations. The tunnel passes through a soft alluvial sedimentary combination of clay (CL), silt (ML), sand (SM, SP) and gravel (GP). The tunnel alignment has been divided into three parts subject to the geological and geotechnical conditions that might be encountered during construction. The investigated geological–geotechnical risks of the soft ground along the TURL2 are oversize grains, soil abrasiveness, liquefaction potential, differential permeability and clogging. The results show that all of the investigated geological–geotechnical risks are present in the TURL2 route and that improvement of the tunnel route soils is essential. For example, to reduce the liquefaction potential, it is necessary to decrease the water table level or else improve the soft soils by injecting cement grout. In addition, in order to reduce clogging of the tunnel route soils, the use of foam as a soil conditioner is appropriate.
14 citations
TL;DR: In this paper, the load-time curves determined from test data showed that the required time to make constant the load variation versus time was more in those samples with 7.5 % cement content compared to those with cement contents of 2.5 and 5 %.
Abstract: Laboratory tests were done to study the load-settlement behaviour. These tests evaluated rigid square footing on sandy soil and a layered system, stabilised with different dimensions and different cement contents. Nineteen plate load tests were done to make evaluations. The soil type used in tests was poorly graded sand in a box container with the following dimensions; cross section 130 cm × 130 cm and depth 100 cm. The soil was compacted in layers 10-cm thick. Cement was added in percentages of 2.5, 5 and 7.5 % by dry weight of soil. Samples were cured for 28 days, after which they were tested. Experimental data demonstrated effectiveness in terms of increasing bearing capacity and reducing settlement of the stabilised soil–cement layers. Results also showed difference in terms of crack propagation mechanism between samples with different cement contents as evaluations of number and direction. The load-time curves determined from test data showed that the required time to make constant the load variation versus time was more in those samples with 7.5 % cement content compared to those with cement contents of 2.5 and 5 %.
14 citations
TL;DR: In this paper, a series of model-scale footing tests are performed to investigate the effects of the unconfined compressive strength, discontinuity spacing and inclination of the rock joint.
Abstract: The subgrade reaction modulus for rock foundations under axial loading is investigated by model footing tests. This study focuses on quantifying a new subgrade reaction modulus by considering rock discontinuities. A series of model-scale footing tests are performed to investigate the effects of the unconfined compressive strength, discontinuity spacing and inclination of the rock joint. Based on the experimental results, it is observed that the subgrade reaction modulus of the rock with discontinuities decreases by up to approximately 60 % of intact rock. In addition, it is found that the modulus of subgrade reaction is proportional to the discontinuity spacing, and it decreases gradually within the range of 0°–30° and tends to increase within the range of 30°–90°.
14 citations
Cites methods from "Foundation analysis and design"
...Among the semi-empirical methods, Vesic’s model is widely applied to mat foundations in the literature (Bowles 1996)....
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Dissertation•
01 Jan 2014
TL;DR: In this paper, a laterally loaded component of an offshore oil rig has been studied, and in particular how to model the soil to best capture the interaction with the soil, abbreviated SSI.
Abstract: The mechanical behavior of structures that are in contact with soil is affected by the interaction between the soil and the structure. This interaction is called Soil-Structure Interaction, abbreviated SSI. Some structures where SSI is especially important are buildings, bridges and oil rigs. In this thesis a laterally loaded component of an offshore oil rig has been studied, and in particular how to model the soil to best capture the interaction with the soil. The component is located in the sea bed, meaning that the interacting soil is completely submerged. A simple and conventional approach is to model the soil using lateral non-linear springs, where the behavior of the springs is dependent on soil type, soil properties, loading and depth below sea bed. It is a widely accepted method in geotechnical engineering, but the one-dimensional springs suffer from certain limitations and an alternative modeling strategy is needed to truly capture the complex three-dimensional behavior of soils, such as modeling the soil as a continuum with solid elements. In this thesis a literature study was carried out to understand the mechanical behavior of soils, and especially the method used to determine the behavior of the non-linear springs. Then, a finite element model of the specific component and the surrounding soil was created in Abaqus/CAE, for three different soil compositions. The soil was modeled both with non-linear springs and as a continuum, and the results from the two modeling strategies were compared, along with identification of limitations and benefits for the two approaches. For the static load case studied it can be concluded that the results are similar, but there are also some notable differences mainly dependent on soil composition and material properties. Continuum soil modeling is more complex and computationally expensive than non-linear springs modeling, but is advantageous in prediction of long-term effects. Future work should focus on determination of a soil’s properties, as these highly influence the results for both modeling strategies. With an accurate characterization of a soil’s behavior, the response of the structure will be predicted as correctly as possible.
14 citations
Cites background or methods from "Foundation analysis and design"
...However, in the absence of available data, [10] presents typical value ranges of Es and ν for different types of soil....
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...Typical values of specific gravity for different soil types are given in [10]....
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...The friction angles used for sand in the previous section with non-linear springs were found from representative values for saturated soils in [10]....
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...The friction angle φ which is used when computing P − y curves for sand is taken from [10], where typical values are listed....
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...The rate of the water outflow depends on the permeability of the soil, where clay has a low permeability and sand a high permeability, as described in [10]....
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TL;DR: In this paper, a small-scale laboratory experimental works to investigate the pullout capacity of a concrete anchor block embedded in air dry sand and located at different distances from yielding boundary wall is presented.
Abstract: The anchor block is a specially designed concrete member intended to withstand pullout or thrust forces from backfill material of an internally stabilized anchored earth retaining wall by passive resistance of soil in front of the block. This study presents small-scale laboratory experimental works to investigate the pullout capacity of a concrete anchor block embedded in air dry sand and located at different distances from yielding boundary wall. The experimental setup consists of a large tank made of fiberglass sheets and steel framing system. A series of tests was carried out in the tank to investigate the load-displacement behavior of anchor block. Experimental results are then compared with the theoretical approaches suggested by different researchers and codes. The appropriate placement of an anchor block and the passive resistance coefficient, which is multiplied by the passive resistance in front of the anchor block to obtain the pullout capacity of the anchor, were also studied.
14 citations