hardening soil model
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2022 ◽  
Vol 07 (01) ◽  
Author(s):  
Serpil Erden ◽  

In this study, the performances of the sand piles in Istanbul's Bağcılar and Zeytinburnu districts has been analyzed using Finite Element Method (FEM). Single and group (triple) piles with various length/diameter ratios (L/D) were placed in the water-saturated soft clay soil. Sand piles were modeled in various L/D ratios (10, 5.71, and 8.57). The distance between the piles was chosen as 2 meters and the group effect was also investigated. A uniformly distributed load of 162 kN/m2 is placed on the ground. In addition, the soil was modeled with the Soft-Soil soil model, the hardening soil model for the infill part, and the sand piles with the Mohr-Coulomb soil model. According to the results , the settlement of the soil decreases by 52.8% for a single pile with an L/D ratio of 8.57. However, the best L/D ratio for triple piles was found to be 5.71. In this case, the settlement decreases by 52.8% compared to the pileless situation. Finally it was concluded that the model with the L/D ratio of 8.57 reduced settlement in the best and the most efficient way.


2021 ◽  
Vol 1203 (2) ◽  
pp. 022067
Author(s):  
Magdalena Kowalska

Abstract Hardening Soil model with the small strain extension (HSS) is lately one of the most popular constitutive models to describe soil behaviour. It is versatile – includes the phenomena of shear strength, stress history, dilatancy, volumetric and shear hardening, hyperbolic stress-strain relationship in axial compression, stiffness dependency on stress and its degradation with strain, as well as the regain of the high stiffness after sharp loading reversals. Even though the model is advanced and complex, accordingly to its authors, it is relatively easy to calibrate based on results of standard tests and empirical formulas. In this paper an attempt was undertaken to estimate the parameters of untypical anthropogenic soils – mixtures of sand and scrap tyre rubber in order to build a database for future numerical analyses. A literature review was conducted and, eventually, the material parameters were determined based on results of a series of laboratory tests (cyclic and monotonic triaxial with bender elements, direct shear) published by researchers of Wollongong University of Australia.


Author(s):  
Raksiri Sukkarak ◽  
Suched Likitlersuang ◽  
Pornkasem Jongpradist ◽  
Pitthaya Jamsawang

2021 ◽  
Vol 7 (3) ◽  
pp. 253
Author(s):  
Anthonius Steven Sutanto ◽  
Paulus Pramono Rahardjo ◽  
Aswin Lim

Pre-stressed ground anchor systems or tieback systems are commonly used at wide and irregular-shaped excavations, with the advantage of lower cost and ease of construction compared to the braced excavations, but they come with the drawback on permits for excavations near buildings and tunnels. Research on tieback systems in sands was generally conducted. However, the studies on the correlation between the retaining wall deflection and pre-stress force are few. The objectives of this paper are to study the influence of pre-stress force, depth of excavation, wall embedment length, and soil shear strength that is represented by soil friction angle on the deflection and soil pressure acting on the retaining wall. The parametric study was conducted on an excavation in sand using the finite element method with the Hardening soil model. The results showed that a 50 kN/m increase in pre-stress force reduced the wall deflection on top of the wall by 0.005–0.083% of excavation depth. However, the pre-stressing influence in reducing wall deflection at excavations became less significant along with the sand density increase due to higher friction angle contribution to excavation stability. Moreover, the pre-stress force needed for stabilization of the wall with long embedment length is smaller than those on the wall with shorter embedment length, since the embedment length increase of 0.25 times of excavation depth reduces wall top deflection by 0.002–0.095% of excavation depth. Also, the increase of soil density reduces the need for wall embedment length, so at dense sand, the embedment length of 0.5 times of excavation depth is sufficient to support the excavation.


Author(s):  
Георгий Владимирович Мосолов ◽  
Илья Леонидович Димов

Уже в ближайшем будущем от использования современных численных методов расчета будет зависеть прогресс в области проектирования оснований и фундаментов зданий и сооружений, поскольку возможности по совершенствованию строительных норм практически исчерпаны. Целью статьи является демонстрация возможностей численных расчетов с использованием современных моделей грунта на примере проектирования фундамента стандартного нефтяного резервуара для хранения нефти и нефтепродуктов. Приведено сравнение результатов расчетов осадки основания резервуара емкостью 30 000 м, выполненных в соответствии с действующими нормами проектирования и методом конечных элементов с применением программного комплекса PLAXIS. В частности, проведены численные расчеты с использованием современных моделей грунта: 1) модели грунта с упрочнением (Hardening Soil model, HS); 2) модели грунта с упрочнением и учетом малых деформаций (Hardening Soil small strain model, HSs). Показано, что использование указанных моделей при наличии требуемого объема исходных данных позволяет существенно уточнить вычисления, выполняемые по нормативным методикам. С учетом полученных результатов определена возможность оптимизации проектных решений при выборе типа фундамента резервуара. In the near future, the progress in design of bases and foundations of buildings and structures will depend on the use of modern numerical calculation methods since the opportunities to improve the building regulations are almost exhausted. This article aims to demonstrate the capabilities of numerical calculations with the use of modern soil models on the example of designing the foundation of a standard oil storage tank for crude oil and petroleum products. This article provides a comparison of the results of the base settlement of a 30,000 m tank calculations made in accordance with the current standards of design and the finite elements method with the use of the PLAXIS software package. In particular, the following numerical calculations with the use of modern soil models have been performed: 1) Hardening Soil model, HS; 2) Hardening Soil small strain model, HSs. It is shown that the use of these models in the presence of the required amount of baseline data can significantly refine the calculations performed according to normative methods. Considering the obtained results, the possibility of optimizing design solutions when selecting the type of foundation of a tank was determined.


2021 ◽  
Vol 13 (11) ◽  
pp. 5782
Author(s):  
Mahdi Bayat ◽  
Amir Homayoon Kosarieh ◽  
Mehran Javanmard

This paper presents the seismic analytic fragility curve of soil nail wall structures. The numerical modeling procedure of the soil nail wall is presented and discussed in detail. Nonlinear elements have been used to provide an accurate finite element modeling of the soil nail wall. The effect of different soil modeling approaches is studied. Detailed procedures to select an efficient intensity measure are presented. Analytical fragility curves for the different performance levels of the soil nail wall are developed. Detailed techniques have been used to generate accurate soil modeling, such as the Mohr-Coulomb model (MC), Hardening Soil model (HS), and Hardening Soil model with Stiffness effect from small strains (HSS), and these are studied. Incremental dynamic analysis (IDA) is implemented to capture the response of the wall from linear to nonlinear levels. The efficiency of the two common intensity measures is studied (PGA and Sa(T1,5%)). It has been demonstrated that HSS and HS models are more reliable techniques for soil modeling. Two common intensity measures are studied, and the efficiency and the sufficiency of them are compared. It has been suggested that Sa(T1,5%) is a more efficient intensity measure than PGA for soil nail structures due to less depression in the IDA results. Different performance levels were defined to develop analytical fragility curves for different damage states.


Author(s):  
Heitor Cardoso Bernardes ◽  
Maurício Martines Sales ◽  
Romulo Rodrigues Machado ◽  
Aleones José da Cruz Junior ◽  
Renato Pinto da Cunha ◽  
...  

2021 ◽  
Vol 3 (2) ◽  
Author(s):  
Samaila Saleh ◽  
Nor Zurairahetty Mohd Yunus ◽  
Kamarudin Ahmad ◽  
Khairun Nissa Mat Said

AbstractOver the last decades, numerical modelling has gained practical importance in geotechnical engineering as a valuable tool for predicting geotechnical problems. An accurate prediction of ground deformation is achieved if models that account for the pre-failure behaviour of soil are used. In this paper, laboratory results of the consolidated drain (CD) triaxial compression tests and one-dimensional consolidation tests of marine clay were used to determine the hardening soil model (HSM) parameter for use in Plaxis 3D analyses. The parameters investigated for the HSM were stiffness, strength and advanced parameters. The stiffness parameters were secant stiffness in CD triaxial compression test ($$E_{50}^{\text{ref}}$$ E 50 ref ), tangent stiffness for primary oedometer loading test $$(E_{\text{oed}}^{\text{ref}} )$$ ( E oed ref ) , unloading/reloading stiffness $$(E_{\text{ur}}^{\text{ref}}$$ ( E ur ref ) and power for the stress-level dependency of stiffness (m). The strength parameters were effective cohesion ($$c_{\text{ref}}^{\text{'}}$$ c ref ' ), effective angle of internal friction ($$\phi^{\text{'}}$$ ϕ ' ) and angle of dilatancy ($$\psi^{\text{'}}$$ ψ ' ). The advanced parameters were Poisson’s ratio for unloading–reloading (ν) and K0-value for normal consolidation $$\left( {K_{\circ}^{\text{nc}} } \right)$$ K ∘ nc . Furthermore, Plaxis 3D was used to simulate the laboratory results to verify the effectiveness of this study. The results revealed that the stiffness parameters $$E_{50}^{\text{ref}} , E_{\text{oed}}^{\text{ref}} , E_{\text{ur}}^{\text{ref}}$$ E 50 ref , E oed ref , E ur ref and m are equal to 3.4 MPa, 3.6 MPa, 12 MPa and 0.7, respectively, and that the strength parameters $$c_{\text{ref}}^{\text{'}}$$ c ref ' , $$\phi^{\text{'}}$$ ϕ ' , $$\psi^{\text{'}}$$ ψ ' and $$K_{\circ}^{\text{nc}}$$ K ∘ nc are equal to 33 kPa, 17.51°, 1.6° and 0.7, respectively. A final comparison of the laboratory results with the numerical results revealed that they were in accordance, which proved the efficacy of the study.


2020 ◽  
Vol 10 (5) ◽  
pp. 6220-6223
Author(s):  
A. H. Bhutto ◽  
G. S. Bhurgri ◽  
S. Zardari ◽  
M. A. Zardari ◽  
B. A. Memon ◽  
...  

The settlement calculation of a multi-story building is a challenging task due to the variation of soil properties and the use of an appropriate constitutive model for the reliable representation of soils’ stress-strain behaviors. In this study, the settlement response of a multi-story building was calculated with the simple Mohr-Coulomb Model (MCM) and the Hardening Soil Model (HSM). The effect of soil modulus of elasticity using both models was investigated on the overall settlement response of the building. Results indicated that MCM overestimated immediate settlement in a range of 50 to 65% compared to HSM. The settlement response of the building calculated with both models was within the allowable range. The results of this study can be helpful for geotechnical engineers working on reliable predictions of the settlement of multi-story buildings.


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