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Some problems of the geotechnical engineering education in Bulgaria
Published in Iacint Manoliu, Ion Antonescu, Nicoleta Rădulescu, Geotechnical Engineering Education and Training, 2020
The following general lecture themes are delivered: Physical Soil properties — density, unit weight, porosity, water soil properties, standard density, grain size distribution.Mechanical properties of soil — compressibility, shear strength, ground water seepage, in-situ testing.Basic mechanical models for determination stress-strain behaviour of soil massifs under surface (foundation’s) and gravitational (unit weight, seepage) loads.Methods for the settlements evaluation.Time-depending stress-strain behavior of the soil massifs. Basic theories of the consolidation and rheology of cohesive soil.Theory of ultimate limit equilibrium.Earth pressure and retaining walls.Stability of natural slopes and earth structure (excavation and embankments).
The design process
Published in A.A. Balkema, Building on Soft Soils, 2017
For any given load, the stability or equilibrium of an earth structure is determined by the shear strength of the soil. The shear strength, in its turn, depends on the magnitude of the strength parameters, such as cohesion and the angle of internal friction and the effective stress level. The methods which have been developed to make it possible to build safe earth structures are intended to: – Restrict the shear stress; for example by gradually bridging the height differences by means of a gradual slope, which may or may not be combined with a berm or carefully raising the stress level by phased filling;– Increase the shear strength in situ; for example by soil replacement or soil improvement.
Evaluating aqaba marine sand geotextile interface shear strength
Published in International Journal of Geotechnical Engineering, 2020
Omar Al Hattamleh, Samer Rabab’Ah, Hussein Aldeeky, Husam Al Qablan
Interface shear strength is a critical factor in the design of many structures involving geotextiles (Hatami and Esmaili 2015; Vieira, Lopes, and Caldeira 2015; Wang et al. 2016; Punetha, Mohanty, and Samanta 2017; Anubhav and Wu. 2015; Dixon and Jones 2005; Bergado et al. 2006; Aldeeky, Al Hattamleh, and Alfoul 2016; Brahim et al. 2016). Extensive geotextile reinforcing of soil is increasingly desired to improve the performance of the earth structure under various soil conditions. Consequently, the use of geotextiles is frequently adopted in reinforced earth retaining walls, embankments, slopes, and foundation beds due to its superiority in active seismic regions. Moreover, low-volume roads, which make up roughly two-thirds of all the roads worldwide, or almost 30 million kilometres of roads, represent one of the biggest fields for the utilization of geotextiles (Keller 2016). Geotextiles have been used for subgrade separation and stabilization over very soft soils, or to reduce the thickness of aggregate placed over moderately soft soils. High-strength woven polypropylene geotextiles are commonly used in geosynthetic-reinforced soil bridge abutments, reducing the cost up to 60% compared to conventional bridge construction (Adams et al. 2011; Keller 2016).
Seismic stability of slope using modified pseudo-dynamic method
Published in International Journal of Geotechnical Engineering, 2019
Nipa Chanda, Sima Ghosh, Manish Pal
where H is height of the earth structure; z is any depth from top surface at which seismic inertia forces acting; ah0 and av0 are amplitude of horizontal and vertical acceleration at the base of soil mass i.e. z = H; ω is the angular frequency of motion; t is time; Vs and Vp are velocity of Shear and Primary wave propagating through the soil; fa is amplification factor. The existing pseudo-dynamic analysis adopted by many researchers in most applications are simplified considering the value of fa = 1 and has certain limitations such asThe zero-stress boundary condition at the ground surface could not be satisfied by the existing pseudo-dynamic method (Bellezza 2014; Choudhury, Katdare, and Pain 2014).The acceleration value assumed to be amplified linearly towards the ground surface, which demands the assumption of amplification factor (Pain, Choudhury, and Bhattacharyya 2015a).The existing pseudo-dynamic method does not consider energy dissipation whereas; all materials have some damping properties.
Experimental study of the Seismic Performance of Different Earth Walls and Their Seismic Retrofitting with Externally Bonded Fibers
Published in Journal of Earthquake Engineering, 2021
Based on the experimental results, we can conclude that the vulnerability of rural communities with numerous earth houses varies significantly due to the soil used for construction. The proposed retrofitting method can be used to strengthen earth dwellings made of clayey and feebly clayey soil to clearly improve the seismic capacity. However, the proposed retrofitting method using externally bonded fibers is found to be ineffective for earth structure made of sandy clayey soil. Further development of the retrofitting methods for earth walls with weak clayey property is needed. Meanwhile, a further study of more soil types with different clayey properties should be involved to better exploring and quantifying the effect of clayey property of soil on seismic response of earth walls.