scholarly journals Effect of Sporosarcina Pasteurii on the strength properties of compressed earth specimens

2018 ◽  
Vol 68 (329) ◽  
pp. 143 ◽  
Author(s):  
E. Bernat-Maso ◽  
L. Gil ◽  
C. Escrig ◽  
J. Barbé ◽  
P. Cortés
Keyword(s):  
Friction Angle ◽  
Research Area ◽  
Strength Properties ◽  
Calcite Precipitation ◽  
Sporosarcina Pasteurii ◽  
Direct Shear Tests ◽  
Apparent Cohesion ◽  
Dilatancy Effect ◽  
Compaction Force ◽  
High Humidity Environment

Microbial biodeposition of calcite induction for improving the performance of rammed earth is a research area that must be analysed in a representative environment. This analysis must consider the compaction force, particle size distribution and curing process as production variables. This paper investigates the effects of adding specific bacteria, Sporosarcina Pasteurii, into compressed earth cubes and the effect of production variables. Uniaxial compressive tests and direct shear tests have been conducted for 80 specimens. The results indicate that calcite precipitation interacts with the drying process of clay/silt resulting in reducing the compressive strength, the apparent cohesion and the friction angle. Finally, bacterial activity, which is more likely in samples cured in a high humidity environment, tends to reduce the dilatancy effect.

scholarly journals Reinforcing Effect of Polypropylene Waste Strips on Compacted Lateritic Soils

2020 ◽  
Vol 12 (22) ◽  
pp. 9572
Author(s):  
Régis Marçal ◽  
Paulo César Lodi ◽  
Natália de Souza Correia ◽  
Heraldo Luiz Giacheti ◽  
Roger Augusto Rodrigues ◽  
...  
Keyword(s):  
Low Cost ◽  
Friction Angle ◽  
Strength Properties ◽  
Clayey Sand ◽  
Lateritic Soils ◽  
Direct Shear Tests ◽  
Apparent Cohesion ◽  
Fiber Reinforcements ◽  
Definition Of ◽  
The Impact

This study evaluated the strength properties of compacted lateritic soils reinforced with polypropylene (PP) waste strips cut from recycled plastic packing with the goal of promoting sustainability through using local materials for engineering work and reusing waste materials as low-cost reinforcements. Waste PP strips with widths of 15 mm and different lengths were uniformly mixed with clayey sand (SC) and clay (CL) soils with the goal of using these materials as low-cost fiber reinforcements. The impact of different PP strip contents (0.25% to 2.0%) and lengths (10, 15, 20, and 30 mm) on the unconfined compressive strength (UCS) of the soils revealed an optimum combination of PP strip content and length. Statistical analysis showed that PP strip content has a greater effect than the PP strip length on the UCS for both soils. Results led to the definition of an empirical equation to estimate the UCS of strip-reinforced soils. The results from direct shear tests indicate that the SC soil showed an increase in both apparent cohesion and friction angle after reinforcement, while the CL soil only showed an increase in friction angle after reinforcement. California bearing ratio (CBR) tests indicate that the SC soil experienced a 70% increase in CBR after reinforcement, while the CBR of the CL soil was not affected by strip inclusion.

scholarly journals Improving Shear Strength Parameters of Sandy Soil using Enzyme-Mediated Calcite Precipitation Technique

2018 ◽  
Vol 20 (2) ◽  
pp. 91 ◽  
Author(s):  
Heriansyah Putra ◽  
Hideaki Yasuhara ◽  
Naoki Kinoshita ◽  
Erizal . ◽  
Tri Sudibyo
Keyword(s):  
Shear Strength ◽  
Sandy Soil ◽  
Friction Angle ◽  
Soil Improvement ◽  
Soil Mass ◽  
Shear Strength Parameters ◽  
Calcite Precipitation ◽  
Strength Parameters ◽  
Direct Shear Tests ◽  
Potential Applications

Several methods have been established for their various potential applications as soil improvement technique, and recently the application of grouting technique using biological process have been proposed. This study discussed the applicability of enzyme-mediated calcite precipitation (EMCP) in improving the shear strength parameters of sandy soil.  In this study, soil specimens were prepared and treated with the grouting solutions composed of urea, calcium chloride, magnesium sulfate and enzyme of urease. Evolutions in the cohesion and internal friction angle of the improved soil were examined through the direct shear tests. The presence of the precipitated materials, comprising 4.1 percent of the soil mass of the treated sand, generated a cohesion of 53 kPa. However, contrary to the improvement of cohesion, the friction angle is relatively constant. It indicated that the application of the EMCP technique has no significant impact on the friction angle

scholarly journals Comparative Study between Silica Fume and Nano Silica Fume in Improving the Shear Strength and Collapsibility of Highly Gypseous Soil

2020 ◽  
Vol 27 (1) ◽  
pp. 72-78
Author(s):  
Ahmed Al-Obaidi ◽  
Marwa Al-Mukhtar ◽  
Omar Al-Dikhil ◽  
Saeed Hannona
Keyword(s):  
Shear Strength ◽  
Silica Fume ◽  
Friction Angle ◽  
Engineering Properties ◽  
Nano Silica ◽  
Direct Shear Tests ◽  
Apparent Cohesion ◽  
Gypsum Content ◽  
Wet Condition ◽  
Gypseous Soil

Soils with highly gypsum content signify known as soils that exhibit collapsibility and sudden failure when being submerged to wetting. Many of the constructions built on this soil showed cracked and/or collapsed at some parts as these soils immersed or leached with water. The utilization of extremely fine materials, for example, Microscale or Nanoscale, is generally utilized these days. This research compared the use of Silica fume (SF) (micro material) and Nano Silica fume (NSF) (Nanomaterial) to explore the capability of these very fine materials to mend the shear strength and collapsibility properties of highly gypseous soils. The soil as Poorly Graded Sand (SP) was used, with a gypsum amount equal to 62%. A succession of direct shear tests and double odometer tests were carried on dry and submarined specimens of soil at various percentages of SF and NSF. The obtained results indicate that mixing the highly gypseous soils with SF or NSF improved the engineering properties of these soils, especially for the wet condition. The average increment in apparent cohesion when adding SF (5-20) percentage varies between (140-310) % in dry soil and (20-40) % in soaked soil. Same results obtained when mixing the gypseous soils with (1-5) % of NSF. Also, the Nanomaterial provided an improvement of the friction angle in dry and submerged cases respectively. Considering that, the SF gives adverse results upon the friction angle of the soil. The SF and the NSF both condensed the dangers of gypseous soil collapsibility. Consequently, the use of NSF can be assertively suggested to improve the engineering characteristics of highly gypseous soils when compared with SF, where only mixing of 3% of NSF gives the best results.

scholarly journals Shear strength of landfills

DYNA ◽  
2015 ◽  
Vol 82 (193) ◽  
pp. 83-92
Author(s):  
Eimar Sandoval Vallejo ◽  
Andrés Ramírez Tazcón ◽  
Diego Cuarán
Keyword(s):  
Shear Strength ◽  
Friction Angle ◽  
Specific Weight ◽  
Strength Properties ◽  
Experimental Program ◽  
Strength Parameters ◽  
Engineering Structures ◽  
Direct Shear Tests ◽  
Decomposition Time ◽  
Valle Del Cauca

Landfills are engineering structures formed with a specific material, whose shear strength properties can be determined in a similar way, as it is done for a geotechnical material. This paper presents results from an experimental program carried out to obtain the strength parameters for Presidente landfill at Valle del Cauca (Colombia). The experimental program included unconsolidated undrained direct shear tests (UU) performed on laboratory reconstituted samples. Variation of the internal friction angle and cohesion, as a function of the specific weight, depth and decomposition time of the landfill was evaluated. Results were also compared to international values used for design purposes. Results showed a remarkable influence of the waste decomposition time in the shear strength. Some relationship with the depth was also found. Obtained strength parameters are within international ranges recommended for design purposes.

scholarly journals Study on the Effects of Grouting and Roughness on the Shear Behavior of Cohesive Soil–Concrete Interfaces

Materials ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3043
Author(s):  
You-Bao Wang ◽  
Chunfeng Zhao ◽  
Yue Wu
Keyword(s):  
Shear Band ◽  
Friction Angle ◽  
Cohesive Soil ◽  
Shear Behavior ◽  
Direct Shear ◽  
Direct Shear Tests ◽  
Apparent Cohesion ◽  
Post Grouting ◽  
Vertical Bearing ◽  
Direct Shear Apparatus

Grouted soil–concrete interfaces exist in bored piles with post-grouting in pile tip or sides and they have a substantial influence on pile skin friction. To study the effect of grouting volume on the shearing characteristics of the interface between cohesive soil and concrete piles with different roughness, grouting equipment and a direct shear apparatus were combined to carry out a total of 48 groups of direct shear tests on cohesive soil–concrete interfaces incorporating the grouting process. The test results showed that the shear behavior of the grouted cohesive soil–concrete interface was improved mainly because increasing the grouting volume and roughness increased the interfacial apparent cohesion. In contrast, increasing the grouting volume and roughness had no obvious increasing effects on the interfacial friction angle. Interfacial grouting contributed to the transition in the grouted cohesive soil from shrinkage to dilation: as the grouting volume increased, the shrinkage became weaker and the dilation became more obvious. The shear band exhibited a parabolic distribution rather than a uniform distribution along the shearing direction and that the shear band thickness was greater in the shearing direction, and it will become thicker with increasing grouting volume or roughness. The analysis can help to understand the shear characteristics of soil–pile interface in studying the vertical bearing properties of pile with post-grouting in tip or sides.

scholarly journals Asperities effect on polypropylene & polyester geotextile-geomembrane interface shear behaviour

2019 ◽  
Vol 92 ◽  
pp. 13017
Author(s):  
Daniel Adeleke ◽  
Denis Kalumba ◽  
Johnny Oriokot
Keyword(s):  
Shear Strength ◽  
Engineering Application ◽  
Friction Angle ◽  
Strength Properties ◽  
Shear Behaviour ◽  
Percentage Increase ◽  
Interface Shear Strength ◽  
Interface Shear ◽  
Direct Shear Tests ◽  
Shear Characteristics

The summary of this paper is focused on the result of a study that used quantitative measures of surface texture as the basis for examining the effects of asperities on the shear characteristics of geotextile-geomembrane interfaces. About 30 large direct shear tests were conducted to evaluate the geotextile-geomembrane interface shear strength properties. The results indicated a non-linear failure envelopes and strain softening behaviour at a normal stress range of 50 – 400 kPa. For most interface tested, the polyester-geotextiles resulted in higher shear strength as compared with polypropylene-geotextiles. Also, the polyester and polypropylene geotextile interface with the high asperity geomembrane produces a similar percentage increase in friction angle at the residual state. For textured geomembranes interfaced with both geotextile, polyester geotextile exhibited relatively less time before failure. Also, asperity height has a more pronounced effect than asperity density on the residual interface shear strength. The outcome of this study would provide a recommendation and guide that can lead to an improved basis for geosynthetics selection in various engineering application.

scholarly journals Sand- and Clay-Photocured-Geomembrane Interface Shear Characteristics Using Direct Shear Test

2021 ◽  
Vol 13 (15) ◽  
pp. 8201
Author(s):  
Lihua Li ◽  
Han Yan ◽  
Henglin Xiao ◽  
Wentao Li ◽  
Zhangshuai Geng
Keyword(s):  
Soil Surface ◽  
Friction Angle ◽  
Direct Shear ◽  
Tensile Crack ◽  
Shear Tests ◽  
Interface Shear ◽  
Direct Shear Tests ◽  
Carbon Black Powder ◽  
Shear Characteristics ◽  
Impermeable Layer

It is well known that geomembranes frequently and easily fail at the seams, which has been a ubiquitous problem in various applications. To avoid the failure of geomembrane at the seams, photocuring was carried out with 1~5% photoinitiator and 2% carbon black powder. This geomembrane can be sprayed and cured on the soil surface. The obtained geomembrane was then used as a barrier, separator, or reinforcement. In this study, the direct shear tests were carried out with the aim to investigate the interfacial characteristics of photocured geomembrane–clay/sand. The results show that a 2% photoinitiator has a significant effect on the impermeable layer for the photocured geomembrane–clay interface. As for the photocured geomembrane–sand interface, it is reasonable to choose a geomembrane made from a 4% photoinitiator at the boundary of the drainage layer and the impermeable layer in the landfill. In the cover system, it is reasonable to choose a 5% photoinitiator geomembrane. Moreover, as for the interface between the photocurable geomembrane and clay/sand, the friction coefficient increases initially and decreases afterward with the increase of normal stress. Furthermore, the friction angle of the interface between photocurable geomembrane and sand is larger than that of the photocurable geomembrane–clay interface. In other words, the interface between photocurable geomembrane and sand has better shear and tensile crack resistance.

General concept of determining the parameters of non-mining walls of ultra-deep diamond deposits development open pits

2021 ◽  
pp. 48-53
Author(s):  
I. V. Zyryanov ◽  
A. N. Akishev ◽  
I. B. Bokiy ◽  
N. M. Sherstyuk
Keyword(s):  
Rock Mass ◽  
Structural Relaxation ◽  
Slope Angle ◽  
Field Tests ◽  
Friction Angle ◽  
Strength Properties ◽  
Strength Characteristics ◽  
Open Pit ◽  
Open Pit Mining ◽  
Relaxation Coefficient

A specific feature of open pit mining of diamond deposits in Western Yakutia is the construction of the open pits in the zone of negative ambient temperatures, which includes thick permafrost rock mass, and which is at the same time complicated by the influence of cryogenic processes on deformation of pit wall benches. The paper presents the comparative analysis of strength characteristics in frozen and thawed rocks, stability of benches during mining, the general geomechanical approach to the determination of parameters of non-mining walls of the ultra-deep open pit diamond mines, and the parameters of nonmining walls and benches. Optimization of open pit wall configuration should primarily be based on the maximum utilization of the strength properties of frozen rocks in combination with the development of new approaches, calculation schemes and methods for assessing stability of open pit walls and benches of unconventional design, including the non-mining vertical benches. The main design characteristic that determines the parameters of open pit walls is the structural tectonic relaxation coefficient, which specifies the calculated value of cohesion in rock mass. For the diamond deposits, the values of the structural relaxation coefficient were obtained in a series of field tests and back calculations. Full-scale tests were carried out both during exploration operations in underground mines and in open pits. The accuracy of determining the values of the structural relaxation coefficient in the range of 0.085–0.11 is confirmed by the parameters of non-mining walls in an open pit mine 385–640 m deep, with overall slope angles of 38–55° and a steeper H 0.35–0.5 lower part having the slope angle of up to 70° with average strength characteristics of 7.85–11.84 MPa and the internal friction angle of 28.1–37.4°. Using the natural load-bearing capacity of rock mass to the full advantage, which the values of the structural relaxation coefficient of deposits show, allows optimization of open pit wall slope design and minimization of stripping operations.

scholarly journals Geotechnical engineering behaviors of gellan gum biopolymer treated sand

2016 ◽  
Vol 53 (10) ◽  
pp. 1658-1670 ◽  
Author(s):  
Ilhan Chang ◽  
Jooyoung Im ◽  
Gye-Chun Cho
Keyword(s):  
Geotechnical Engineering ◽  
Friction Angle ◽  
Soil Improvement ◽  
Gellan Gum ◽  
Strengthening Effect ◽  
Calcite Precipitation ◽  
Unconfined Compression Test ◽  
Sand Particles ◽  
Engineering Practices ◽  
Moisture Conditions

Biological approaches have recently been explored as environmentally friendly alternatives to engineered soil methods in geotechnical engineering practices. The use of microbial induced calcite precipitation, reactive enzymes, and microbial polymers, such as biopolymers, in soil improvement has been studied by researchers around the world. In the present study, gellan gum, a microbial polysaccharide generally used in the food industry due to its hydrogel rheology, was used to strengthen sand. The effects of gellan gum on the geotechnical behaviors of cohesionless sand were evaluated through a series of experimental programs including an unconfined compression test, direct shear test, falling head permeability test, and scanning electron microscopy. The geotechnical properties (friction angle, cohesion, and unconfined compressive strength) of gellan gum–treated sands were determined based on varying moisture conditions: initial, dried, and re-submerged. Gellan gum has a distinct strengthening effect on cohesionless sands through artificial cohesion that varies with the moisture conditions. The strengthening effect of gellan gum on sand appears to be a result of the combination of enhanced bonding between unreactive sand particles and the agglomeration of sand particles through hydrogel condensation, in which the agglomerated sand particles behave as enlarged aggregates in soil.

scholarly journals AN INVESTIGATION ON THE EFFECTS OF MICRO-PARAMETERS ON THE STRENGTH PROPERTIES OF ROCK

2021 ◽  
Vol 36 (1) ◽  
pp. 111-119
Author(s):  
Behzad Jafari Mohammadabadi ◽  
Kourosh Shahriar ◽  
Hossein Jalalifar ◽  
Kaveh Ahangari
Keyword(s):  
Mechanical Properties ◽  
Numerical Simulation ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Friction Coefficient ◽  
Critical Stress ◽  
Friction Angle ◽  
Strength Properties ◽  
Brazilian Tensile Strength ◽  
The Relationship

Rocks are formed from particles and the interaction between those particles controls the behaviour of a rock’s mechanical properties. Since it is very important to conduct extensive studies about the relationship between the micro-parameters and macro-parameters of rock, this paper investigates the effects of some micro-parameters on strength properties and the behaviour of cracks in rock. This is carried out by using numerical simulation of an extensive series of Uniaxial Compressive Strength (UCS) and Brazilian Tensile Strength (BTS) tests. The micro-parameters included the particles’ contact modulus, the contact stiff ness ratio, bond cohesion, bond tensile strength, the friction coefficient and the friction angle, and the mechanical properties of chromite rock have been considered as base values of the investigation. Based on the obtained results, it was found that the most important micro-parameters on the behaviour of rock in the compressive state are bond cohesion, bond tensile strength, and the friction coefficient. Also, the bond tensile strength showed the largest effect under tensile conditions. The micro-parameter of bond tensile strength increased the rock tensile strength (up to 5 times), minimized destructive cracks and increased the corresponding strain (almost 2.5 times) during critical stress.

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