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1

Effects of Contamination with Gasoline and Diesel Oil on Shear Strength of Coarse Grained Soil

Brzeziński Bartłomiej, Olchawa Andrzej

Rocznik Ochrona Środowiska

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2023

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Tom 25

222--227

EN

The paper presents research results into the influence of motor fuels on the shear strength of coarse-grained soil. The soil was classified following the unified soil classification system PN-EN ISO 14668-1 as saGr. The soil samples were artificially contaminated with three percentage ratios of motor fuels 5, 7.5 and 10% in relation to the dry mass of the soil skeleton. The test results have shown that motor fuel contamination significantly impacts the tested soil's mechanical properties. Increasing the content of impurities causes a significant decrease in shear strength parameters. For soil contaminated with 5%, 7.5% and 10% of motor fuel, i.e. gasoline or diesel, the angle of internal friction decreased by 8%, 15% and 20%, respectively. Along with the impurities increase, the soil's ultimate bearing capacity, calculated following EC-7, showed a dramatic decrease. The decrease was 40%, 57% and 66% respectively.

2

Shear strength of compacted Chlef sand: effect of water content, fines content and others parameters

Bouri Djamel, Krim Abdallah, Brahim Abdelkader, Arab Ahmed

Studia Geotechnica et Mechanica

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2020

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Vol. 42, nr 1

18--35

EN

This paper presents a laboratory study of the combined effect of the water content and fines content on the mechanical behaviour of Chlef sand in a medium dense state (RD = 65%) and dense state (RD = 80%). Several mechanical parameters were evaluated such as shear strength, cohesion and friction angle at different water content w = 0, 1, 2 and 3% and different fines content Fc = 0, 10, 20, 30 and 40%. The test results showed that the shear strength of Chlef sand decrease with the increase fines content Fc = 0 to 40%, our tests result also showed that the water content has a significant influence on the shear strength which decreases with the increase in the water content w = 0 to 3%. The fines content and the water content have a significant influence on the mechanical parameters c and ɸ. Cohesion increases with the percentage of fines and decreases with the increase of the water content while the friction angle decreases with the increase the fines content and the water content.

3

Nonlinear shear constitutive model for peak shear-type joints based on improved Harris damage function

Xie Shijie, Lin Hang, Wang Yixian, Cao Rihong, Yong Rui, Du Shigui, Li Jiangteng

Archives of Civil and Mechanical Engineering

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2020

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Vol. 20, no. 3

454--467

EN

The majority of jointed rock mass failures mainly occur along the joints in shear mode, which promotes a wide investigation on the proposal of a reasonable and reliable shear constitutive model of rock joints. In this paper, based on Improved Harris function and laboratory shear tests, a new constitutive model of saw-tooth joints was proposed. Firstly, a series of laboratory direct shear tests were carried out on saw-tooth joint specimens made of rock-like materials (cement mortar) to obtain the shear stress-displacement curves. Subsequently, the test results were divided into sliding failure type and peak shear type according to whether there is a significant stress drop between peak stress and residual stress. It is assumed that rock elements can be divided into undamaged parts and damaged parts during the shearing process. The stress-displacement relation of the undamaged part satisfies Hooke’s law, while the damaged part provides residual stress. Via the comparison with commonly used micro-element failure probability density functions, the Improved Harris distribution function was selected as the standard to characterize the strength of micro rock units. Finally, derived from the theory of damage statistical mechanics, a damage statistical constitutive model was proposed, which can reflect the deformation characteristics of rock joints. Compared with previous models and experimental data, the model proposed in this paper can represent the trend of peak shear curve variation with higher accuracy, the parameters are easy to be solved and have obvious physical significance, which verifies the advantages and applicability of this model.

4

Shear Strength Enhancement of Cemented Reinforced Sand: Role of Cement Content on the Macro-Mechanical Behavior

Boutouba Kheira, Benessalah Ismail, Arab Ahmed, Henni Ahmed Djafar

Studia Geotechnica et Mechanica

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2019

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Vol. 41, nr 4

200--211

EN

Sands reinforced by hydraulic binders (cement) have constituted in recent decades a major asset for the expansion of several areas of engineering. The mechanical behavior of sand-cement mixtures has undergone some controversies studied on the Chlef sand. In this paper, we present an experimental study to investigate the mechanical behavior of a sandy soil reinforced by a hydraulic binder (cement), using the direct shear apparatus emphasizing on the shear strength characteristics and the vertical deformation variation of cemented reinforced sand. The parameters used in this study are mainly: relative density (Dr = 80%), normal stress (σn = 100, 200, 400 kPa), water content (3, 7 and 10%), cement content (2.5, 5, 7.5 and 10 %) and cure time (7, 14 and 28 days). The experimental results show that the mechanical characteristics in terms of internal cohesion (C) and internal frication angle (φ) give a better mechanical performance with the binder inclusion, and the cure conditions play an effective role on the improvement of the shear strength. This result also showed that 10% of the cement content gave us a maximum value of shear strength and an optimal influence on the mechanical characteristics. The addition of cement not only improves the shear strength of soil, but also provides diversity in the resistance against the deformations imposed load, which can be established by a dilatant character.

5

Laboratory Study of Soil Shear Strength Improvement with Polyester Fibres

Nguyen Giang

Fibres & Textiles in Eastern Europe

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2019

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Vol. 27, no. 2 (134)

91--99

EN

The paper deals with a laboratory study of soil shear strength improvement with polyester fibres. Soils CS and CH were mixed with polyester fibres of 70mm length as random reinforcement in an amount of 0.5% and 1.0%. Improvement of the soil shear strength was measured by direct shear tests with a shear box of 0.3 × 0.3 × 0.08 m size. Results show that the improvement rate is different for CS and CH. For soil CS, polyester fibres increased the angle of the internal friction (even by 45.2% with 1% of polyester fibres), as well as the cohesion (by 48.2% with 0.5% of polyester fibres), but also decreased it (by 27.5% with 1% of polyester fibres). For soil CH, fibres decreased the angle of internal friction (by 7.8%) but increased the cohesion by 322.7%. Analysis of the specimen number and result uncertainty shows that various combinations of the 3 specimens provide different results; hence tests with at least 4 specimens are recommended.

PL

Artykuł dotyczy laboratoryjnego badania poprawy wytrzymałości na ścinanie gleby z zastosowaniem włókien poliestrowych. Gleby CS i CH zmieszano z włóknami poliestrowymi o długości 70 mm jako zbrojenie losowe w ilości 0,5% i 1,0%. Poprawę wytrzymałości na ścinanie gleby mierzono za pomocą testów bezpośredniego ścinania przy użyciu zestawu ścinania o wymiarach 0,3 × 0,3 × 0,08 m. Wyniki pokazują, że wskaźnik poprawy jest inny dla CS i CH. W przypadku CS włókna poliestrowe zwiększyły kąt tarcia wewnętrznego nawet o 45,2% przy udziale 1% włókien poliestrowych, a także zwiększyły spójność o 48,2% przy udziale 0,5% włókien poliestrowych, ale także zmniejszyły ją o 27,5 % z udziałem 1% włókien poliestrowych. W przypadku gleby CH włókna poliestrowe zmniejszyły kąt tarcia wewnętrznego o 7,8%, ale zwiększyły spójność o 322,7%. Analiza liczby próbek i niepewności wyniku pokazuje, że różne kombinacje 3 próbek dają różne wyniki, dlatego zaleca się testy z co najmniej 4 próbkami.

6

A laboratory investigation on shear strength behavior of sandy soil: effect of glass fiber and clinker residue content

Bouaricha L., Djafar Henni A., Lancelot L.

Studia Geotechnica et Mechanica

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2017

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Vol. 39, nr 4

3--15

EN

A study was undertaken to investigate the shear strength parameters of treated sands reinforced with randomly distributed glass fibers by carrying out direct shear test after seven days curing periods. Firstly, we studied the fiber content and fiber length effect on the peak shear strength on samples. The second part gives a parametric analysis on the effect of glass fiber and clinker residue content on the shear strength parameters for two types of uniform Algerian sands having different particle sizes (Chlef sand and Rass sand) with an average relative density Dr = 50%. Finally, the test results show that the combination of glass fiber and clinker residue content can effectively improve the shear strength parameters of soil in comparison with unreinforced soil. For instance, there is a significant gain for the cohesion and friction angle of reinforced sand of Chlef. Compared to unreinforced sand, the cohesion for sand reinforced with different ratios of clinker residue increased by 4.36 to 43.08 kPa for Chlef sand and by 3.1 to 28.64 kPa for Rass sand. The feature friction angles increased from 38.73° to 43.01° (+4.28°), and after the treatment, clinker residue content of soil evaluated to 5% (WRC = 5%).

7

Scale effect in direct shear tests on recycled concrete aggregate

Soból E., Sas W., Szymański A.

Studia Geotechnica et Mechanica

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2015

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Vol. 37, nr 2

45--49

EN

The depletion of natural resources is forcing researchers to explore the possibilities of new aggregates, such as recycled concrete aggregate (RCA). In this article, the mechanical properties and the influence of the size of the direct shear box on the obtained parameters were examined. The study was conducted in two apparatus: medium (120 × 120 mm) and large (250 × 250 mm). In each of these devices, a total of 6 tests were performed: 3 for dry sample and 3 at optimum moisture content. From the results, the conclusions described below have been drawn.

8

Comparison of sandy soil shear strength parameters obtained by various construction direct shear apparatuses

Amsiejus J., Dirgeliene N., Norkus A., Skuodis S.

Archives of Civil and Mechanical Engineering

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2014

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Vol. 14, no. 2

327--334

EN

An analysis of test results performed by common type of direct shear apparatuses shows that normal stress on the shear plane of soil sample is not equal to vertical component of distributed external load applied to the top of soil sample. Performed measurements cleared that only 65–85% of total vertical load is transmitted to the sample shear plane. Thus, determining of the soil shear strength depends on shear apparatus construction, i.e. on actual magnitude of vertical load transmitted to the shear plane. The paper presents an analysis of shear strength parameters of sand determined by two different construction of direct shear apparatuses with movable lower shear ring. The soil shear strength parameters by employing direct shear apparatus SPF-2 have been obtained under constant vertical load and measuring the vertical load at different positions, namely: at the bottom and that of at the top of soil sample, respectively. The soil strength parameters by employing the universal shear testing device ADS 1/3 were determined under two conditions, namely: by maintaining constant soil volume and that of for constant vertical load, respectively. In both cases the vertical load was measured at the top of soil sample.

9

Symulacja komputerowa parametrów wytrzymałościowych gleby na bazie modeli Janosi-Hanamoto oraz Coulomba-Mohra

Błaszkiewicz Z., Szafarz A.

Inżynieria Rolnicza

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2008

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R. 12, nr 7(105)

15-21

PL

W pracy przedstawiono program komputerowy do wyznaczania parametrów wytrzymałościowych gleby i symulacji zależności naprężeń ścinających od poziomego odkształcenia gleby obliczanej na bazie modeli Janosi-Hanamoto i Coulomba-Mohra. W badaniach symulacyjnych wykazano, że modele dobrze opisują nowe zależności naprężeń ścinających od poziomego odkształcenia gleby uzyskane metodą zmodyfikowaną w aparacie bezpośredniego ścinania przy narastających naprężeniach normalnych. Testy zostały przeprowadzone dla wilgotności gleby 4% wag. i dla maksymalnych naprężeń normalnych 70 i 130 kPa.

EN

The paper presents a computer application used to determine soil strength parameters and to simulate relations between shearing stresses and horizontal soil strain, computed using the Janosi- Hanamoto and Coulomb-Mohr models. Simulation tests have proven that these models characterize well new relations between shearing stresses and horizontal soil strain, obtained using the modified method in a direct shear apparatus at growing normal stress values. The tests were performed for soil humidity 4% by weight, and for maximum normal stress values of 70 and 130 kPa.

10

Wyznaczanie wytrzymałości częściowo odwodnionych osadów filtracyjnych

Składzień J., Szymków J.

Inżynieria i Aparatura Chemiczna

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2005

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Nr 4

33--34

PL

W pracy zaprezentowano metodę wyznaczania wytrzymałości osadów filtracyjnych częściowo odwodnionych przez przedmuchiwanie powietrzem. Osady takie powstają m.in. w wyniku filtracji plackowej realizowanej na próżniowych filtrach bębnowych. Metoda pozwala wyznaczyć wytrzymałość osadów filtracyjnych o nasyceniu cieczą w granicach od 20 do 80% tj. w obszarze kapilarnym. Metoda została przetestowana na osadach filtracyjnych złożonych z cząsteczek węglanu wapnia o przeciętnej średnicy 43 urn. Zaprezentowane wyniki uzyskano na podstawie testów bezpośredniego ścinania oraz z eksperymentów odwadniania osadów przez przedmuchiwanie powietrzem.

EN

In the paper the procedure for strength determination of partially dewatered filter cakes was proposed and verified. Filter cakes considered were dewatered in vacuum filters by airflow through the filter cake. The method is apphcable for filter cakes with saturation in the range from 20% to 80%, i.e. in the capillary region. Verification was carried out in filter cakes consisted of carbon carbonate partieles with the mean diameter equal to 43 urn. The results were obtained on the basis of direct shear tests and the determination of a capillary curve.