scholarly journals Evaluation of the Shear Strength Behavior of TDA Mixed with Fine and Coarse Aggregates for Backfilling around Buried Structures

2021 ◽  
Vol 13 (9) ◽  
pp. 5087
Author(s):  
Hany El Naggar ◽  
Ali Iranikhah
Keyword(s):  
Large Scale ◽  
Clayey Soil ◽  
Earth Pressure ◽  
Shear Resistance ◽  
Unit Weight ◽  
Direct Shear ◽  
Clayey Soils ◽  
Buried Structures ◽  
Angle Of Internal Friction ◽  
Lateral Earth Pressure

Although some discarded tires are reused in various applications, a considerable number end up in landfills, where they pose diverse environmental problems. Waste tires that are shredded to produce tire-derived aggregates (TDA) can be reused in geotechnical engineering applications. Many studies have already been conducted to examine the behavior of pure TDA and soil-TDA mixtures. However, few studies have investigated the behavior of larger TDA particles, 20 to 75 mm in size, mixed with various types of soil at percentages ranging from 0% to 100%. In this study, TDA was mixed with gravelly, sandy, and clayey soils to determine the optimum soil-TDA mixtures for each soil type. A large-scale direct shear box (305 mm × 305 mm × 220 mm) was used, and the mixtures were examined with a series of direct shear tests at confining pressures of 50.1, 98.8, and 196.4 kPa. The test results indicated that the addition of TDA to the considered soils significantly reduces the dry unit weight, making the mixtures attractive for applications requiring lightweight fill materials. It was found that adding TDA to gravel decreases the shear resistance for all considered TDA contents. On the contrary, adding up to 10% TDA by weight to the sandy or clayey soils was found to increase the shear resistance of the mixtures. Adding up to 10% TDA by weight to the clayey soil also sharply increased the angle of internal friction from 18.8° to 32.3°. Moreover, it was also found that the addition of 25% TDA by weight to the gravelly or sandy soils can reduce the lateral earth pressure on buried structures by up to 20%. In comparison, adding 10% TDA to clay resulted in a 36% reduction in the lateral earth pressure.

Research on the Prefabricated Prestressed Cylinder Foundation of Wind Turbines in the Soft Soil Region

2011 ◽  
Vol 368-373 ◽  
pp. 461-464
Author(s):  
Ren Le Ma ◽  
Ming Yi Zhang
Keyword(s):  
Large Scale ◽  
Wind Farm ◽  
Rapid Development ◽  
Soft Soil ◽  
Earth Pressure ◽  
Element Analysis ◽  
Inland Wetlands ◽  
Lateral Earth Pressure ◽  
Practical Engineering ◽  
Improved Design

With the rapid development of inland wind farm in China, the costal wind farm still has not got large-scale development as the result of the higher cost of fan foundation and the more difficulty of construction. The prefabricated prestressed cylinder foundation (PPC foundation), as a new type of wind turbine foundation designed for the soft soil region such as the inter-tidal coastal zone and inland wetlands, is introduced in this paper. The condition of lateral earth pressure distribution around the foundation which determines the flexural capacity of fan foundation in the soft soil is studied. Through theoretical analysis and mathematical derivation, the result shows that the lateral earth pressure around PPC foundation is changed with depth by 1.5th power curve which has good fitting to the finite element analysis result. The simplified and improved design process is applied into the practical engineering and the good economy of PPC foundation is proved.

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.

Full-scale shake table investigation of bridge abutment lateral earth pressure

2009 ◽  
Vol 42 (1) ◽  
pp. 39-46 ◽  
Author(s):  
Patrick Wilson ◽  
Ahmed Elgamal
Keyword(s):  
Large Scale ◽  
Dynamic Pressure ◽  
Inertial Force ◽  
Earth Pressure ◽  
Shake Table ◽  
Passive Force ◽  
Dense Sand ◽  
Lateral Earth Pressure ◽  
Bridge Abutment ◽  
Force Displacement

During strong seismic excitation, passive earth pressure at the abutments may provide resistance to longitudinal displacement of the bridge deck. The dynamic pressure component may also contribute to undesirable abutment movement or damage. Current uncertainty in the passive force-displacement relationship and in the dynamic response of abutment backfills continues to motivate large-scale experimentation. In this regard, a test series is conducted to measure static and dynamic lateral earth pressure on a 1.7 meter high bridge abutment wall. Built in a large soil container, the wall is displaced horizontally into the dense sand backfill, in order to record the passive force-displacement relationship. The wall-backfill system is also subjected to shake table excitation. In the conducted tests, lateral earth pressure on the wall remained close to the static value during the low to moderate shaking events (up to about 0.5g). At higher levels of input acceleration, a substantial portion of the backfill inertial force started to clearly act on the wall.

scholarly journals Effect of the Particle Size on the TDA Shear Strength and Stiffness Parameters in Large-Scale Direct Shear Tests

Geotechnics ◽  
2021 ◽  
Vol 1 (1) ◽  
pp. 1-17 ◽  
Author(s):  
Hany El Naggar ◽  
Khaled Zahran ◽  
Ahmed Moussa
Keyword(s):  
Particle Size ◽  
Shear Strength ◽  
Large Scale ◽  
Fire Hazard ◽  
Unit Weight ◽  
Direct Shear ◽  
Large Area ◽  
Maximum Particle Size ◽  
Maximum Particle ◽  
Strength And Stiffness

The increase in the number of discarded tires every year is becoming a major issue all over the world. Tires stockpiles and landfills have become a critical issue as they are considered a fertile environment for the breeding of rats and insects, a real fire hazard that may take up to months to extinguish and occupy a valuable, large area of land. One of the safest effective ways of recycling tires is that to use them as backfilling material, among different usages, in civil engineering projects due to their low unit weight and specific gravity. However, to use any material in the construction industry, several material properties must be evaluated, including the shear strength and stiffness parameters. Many factors control the measured parameters. One main factor that is known to have a significant effect is the particle size. This paper focuses on evaluating the effect of the particle size on the shear strength and stiffness parameters of six tire-derived aggregate (TDA) samples having particle sizes range between (9.5–101.6 mm) using a large-scale direct shear machine. The tests were conducted under three normal stresses: 50.1, 98.8 and 196.4 kPa using a constant shearing rate of 0.5 mm/min. The results of this study showed an increasing angle of internal friction as the maximum particle size increases. Moreover, the secant shear modulus also exhibited an increase by increasing the maximum particle size. Furthermore, equations to estimate the stress-strain curves of Type A-TDA for different confidence levels were developed, and their predictions were compared with experimental results to assess their suitability.

scholarly journals Mechanical Properties of Scrap Tire Crumbs-Clayey Soil Mixtures Determined by Laboratory Tests

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
ShanShan Li ◽  
Dayong Li
Keyword(s):  
Mechanical Properties ◽  
Laboratory Tests ◽  
Clayey Soil ◽  
Unit Weight ◽  
Direct Shear ◽  
Scrap Tire ◽  
Unconfined Compression Test ◽  
Fill Material ◽  
Soil Mixtures ◽  
Tire Crumbs

Some laboratory tests, such as Proctor compaction test, direct shear and cyclic direct shear tests, consolidation test, and unconfined compression test, were performed on scrap tire crumbs-clayey soil mixtures to study the mechanical properties of the mixtures. The results show that (1) the maximum dry unit weight and the corresponding optimum moisture content of the mixtures decrease rapidly with the increase of scrap tire crumbs content (CSTC), showing good potential for using the mixtures as lightweight fill material; (2) it is not possible to prepare the mixture when CSTC exceeds 30% due to the occurrence of cracks in the mixture after removing from a mould; and (3) the shear strength of mixtures approximately increases by 20% when CSTC is up to 30%, while the residual strength decreases by 15%, compared with that of pure clayey soil. During shearing, the dilation of the mixtures occurs, particularly under the condition of a high CSTC and a low vertical pressure. Besides, the compressive strength and consolidation settlement of the mixtures decrease with CSTC increasing. The results indicate that it is possible for scrap tire crumbs used to improve clayey soil, which is suitable to act as a fill material.

Lateral Earth Pressure Coefficient of Soils Subjected to Freeze–Thaw

2017 ◽  
Vol 140 (2) ◽  
Author(s):  
Xiaodong Zhao ◽  
Guoqing Zhou ◽  
Bo Wang ◽  
Wei Jiao ◽  
Jing Yu
Keyword(s):  
Pressure Coefficient ◽  
Earth Pressure ◽  
Retaining Walls ◽  
Saturated Soil ◽  
Frozen Soils ◽  
Freeze Thaw ◽  
Lateral Earth Pressure ◽  
Soil Deposits ◽  
Earth Pressure Coefficient ◽  
Water Saturated

Artificial frozen soils (AFS) have been used widely as temporary retaining walls in strata with soft and water-saturated soil deposits. After excavations, frozen soils thaw, and the lateral earth pressure penetrates through the soils subjected to freeze–thaw, and acts on man-made facilities. Therefore, it is important to investigate the lateral pressure (coefficient) responses of soils subjected to freeze–thaw to perform structure calculations and stability assessments of man-made facilities. A cubical testing apparatus was developed, and tests were performed on susceptible soils under conditions of freezing to a stable thermal gradient and then thawing with a uniform temperature (Fnonuni–Tuni). The experimental results indicated a lack of notable anisotropy for the maximum lateral preconsolidated pressures induced by the specimen’s compaction and freeze–thaw. However, the freeze–thaw led to a decrement of lateral earth pressure coefficient  K0, and  K0 decrement under the horizontal Fnonuni–Tuni was greater than that under the vertical Fnonuni–Tuni. The measured  K0 for normally consolidated and over-consolidated soil specimens exhibited anisotropic characteristics under the vertical Fnonuni–Tuni and horizontal Fnonuni–Tuni treatments. The anisotropies of  K0 under the horizontal Fnonuni–Tuni were greater than that under the vertical Fnonuni–Tuni, and the anisotropies were more noticeable in the unloading path than that in the loading path. These observations have potential significances to the economical and practical design of permanent retaining walls in soft and water-saturated soil deposits.

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