Formation Of Tensile Cracks Research Articles

Experimental Investigation on Rock Failure Characteristics of Large-Span Goafs Using Digital Image Correlation Analysis and Acoustic Emission Monitoring

Rockmass in deep mining is highly susceptible to large-scale collapses under high stress and blast-induced disturbances, leading to casualties and economic losses. To investigate the evolution characteristics of goaf instability and the types of seismic sources that induce instability, an experiment on goaf instability was designed under uniaxial compression conditions based on actual mining operations. The entire experimental process was monitored using digital image correlation analysis and acoustic emission monitoring. By calculating the digital speckle field on the surface of the rock specimen during the experiment, the evolution characteristics of the deformation and strain fields from the beginning of loading to complete failure were analyzed. The study explored the dynamic behavior of cracks from initiation to propagation and eventually inducing large-scale collapse. The results show that the instability process of the goaf begins with the formation of tensile cracks. As stress increases, shear cracks occur in the specimen, leading to macroscopic failure. Furthermore, based on the differences in overall microfracture types measured by RA-AF characteristic parameters during specimen failure, large amplitude acoustic emission events corresponding to the formation of dominant macroscopic cracks were selected, and the focal mechanisms of these events were inverted. The results indicate that shear failure sources are significantly more prevalent than tensile failure sources in acoustic emission events leading to goaf instability. These findings can provide useful guidance for the support design and the prevention and control of rockmass instability disasters.

Corrosion effects on flexural behaviour of EPS sandwich concrete panels: a study using acoustic emission technique

The experimental research utilized expanded polystyrene (EPS) panels sized at 1300 × 600 × 130 mm (length × width × thickness) and induced with corrosion via an impressed current method. Varied extents of corrosion were applied for 120, 240, 360, and 480 h, resulting in mass loss percentages of 6.67%, 8.41%, 10.76%, and 18.13% of reinforcement in different panels. The flexural testing along with acoustic emission (AE) monitoring were performed for evaluation of EPS panels. Results obtained defend the correlation of AE energy with the load energy in the EPS panels. The AE parameters of rise angle and average frequency assist in distinguishing between tensile and shear crack types. The energy released during tensile crack formation in EPS panels is minimal compared to that during shear crack formation. These findings are a basis for further AE investigations into EPS panels and developing AE sensor-based methods for identifying corrosion-induced degradation in EPS panels within structures.

Shear Performance of Prefabricated Steel Ultra-High-Performance Concrete (UHPC) Composite Beams under Combined Tensile and Shear Loads: Single Embedded Nut Bolts vs. Studs

Ultra-high-performance concrete (UHPC) is widely used in precast concrete-steel composite beams because of its beneficial properties, including reduced structural weight, higher flexural rigidity, and reduced tensile crack formation. In comparison to conventional steel-concrete composite beams, steel-UHPC composite beams exhibit superior characteristics, including reduced structural deadweight, enhanced flexural stiffness, and the capacity to withstand tensile cracking. One successful attempt at meeting the current demands for expedited girder engineering is the development of steel-UHPC composite beams with full-depth precast slabs as key components affecting the overall structural performance using dismountable single embedded nut bolts (SENBs) and widely used studs as competitive alternatives. In contrast, shear connectors are exposed to a combined tensile and shear stress in service life rather than shear only. The corresponding scientific problem is the problem of combined effects under stress in practical applications, but there is currently no relevant research. The shear performance of SENBs in precast steel-UHPC composite beams under tension and shear loads remains unclear. For this purpose, ten push-out specimens and theoretical analyses were performed in this paper, considering the influence of the connector’s type and tensile-to-shear ratio. However, ten specimens were conducted to investigate the tensile-to-shear ratio, and the connector’s type on shear performance is limited. In the future, an increasing number of specimens and test parameters should be considered to investigate the shear performance of precast steel-UHPC composite beams. An increase in the tension-to-shear ratio resulted in a substantial reduction in the ultimate shear capacity, initial shear stiffness, and ductility of the studs. The increase in the tensile-shear ratio from 0 to 0.47 resulted in a 16.9% decline in the ultimate shear capacity, a 30.4% reduction in the initial shear stiffness, and a 21.7% decrease in the ductility of the Series I samples. However, an increase in the tensile-to-shear ratio of the Series II samples from 0 to 0.47 resulted in a 31.3% decline in ultimate shear strength, a 33.2% decline in initial shear stiffness, and a 41.9% decline in ductility. The SENBs demonstrated minimal deviations in ultimate shear capacity compared to their stud counterparts, despite exhibiting notable differences in shear stiffness, and ductility. A lower tensile-to-shear ratio was recommended in practical engineering, which might achieve a larger ultimate shear capacity, stiffness, and ductility. The design-oriented models with enhanced applicability were developed to predict the tension-shear relationship and the load-slip curve of SENBs in prefabricated steel-UHPC composite beams subjected to combined tensile and shear loads. For a tensile-shear relationship model, the point error range was 0 to 0.08, with an average error of 0.03. The square coefficient (R2) was 0.99 for a load-slip curve model. The study findings could offer a credible reference for the shear mechanism of such economical and environmentally friendly precast steel-UHPC composite beams in accelerated bridge construction.

Mechanical properties and damage evolution features in uniaxial compression with non-coincident interlayer contact in double-block ballastless track

As interlayer cracking has become as a significant issue in ballastless tracks, investigating the mechanical properties and damage characteristics during uniaxial compression with non-coincident contact is vital for enhancing the operational performance of ballastless tracks. This study conducted experiments on interlayer non-coincident contact damage in double-block ballastless tracks with nominal normal pressures of 0.666 MPa, 1.244 MPa, 2.489 MPa, and 3.733 MPa. The research explored the relationship between normal load and normal deformation stiffness, analyzed the interlayer contact damage mechanism of concrete, and investigated the damage evolution mechanism under non-coincident contact conditions based on Acoustic Emission (AE) signals. The findings indicate that: I) When the nominal pressure is respectively less than and greater than 1.333 MPa, the normal deformation stiffness and normal load satisfy linear and power function relationships, respectively. II) The interaction of interlayer protrusions under non-coincident contact, combined with the outward expansion resulting from interlayer mutual compression deformation, are two significant factors contributing to the formation of tensile cracks, while the presence of significant shear stresses directly beneath the interlayer contact points is the primary cause of shear cracks. III) After loading, The ballastless track slab matrix remains undamaged, while the supporting layer matrix may experience comprehensive cracking when the nominal pressure exceeds 1.333 MPa. IV) During the stage of only interlayer interface damage, both tensile and shear cracks are the primary causes of concrete damage. In the stage where damage occurs to both the interlayer interface and matrix, tensile cracks play a dominant role. However, when comprehensive matrix cracking occurs, shear cracks take on a dominant role. The outcomes of this study contribute to a deeper understanding of the damage mechanisms of ballastless tracks under train loads following interlayer cracking. Particularly focusing on the evolution characteristics of damage under high interlayer pressure.

Understanding the static rate dependence of early fracture behavior of cemented paste backfill using digital image correlation and acoustic emission techniques

In mining engineering practice, cemented paste backfill (CPB) are subjected to loads at different static rates, so it is crucial to clarify the mechanical evolution mechanism of CPBs at different static rates. This work aims to understand the early fracture evolution mechanism of the CPB at static rates. First, the CPB with different static rates were monitored in real-time using acoustic emission (AE) and digital image correlation (DIC) techniques, and the effects of static rates on the CPB compressive strength as well as failure characteristics were analyzed; then, the intrinsic relationship between AE rise time/amplitude (RA) and average frequency (AF) was used to classify the crack types, and AE b-values and RA fractal dimensions were discussed for the crack evolution of the scale; finally, the strain field, displacement field, and dilation characteristics of the CPB were investigated. The results show that the increase in static rate increases the compressive strength of the CPB increase first and then decreases, and there is a critical loading rate effect. The final failure form of the specimen is transformed from tensile failure to tensile-shear composite failure with the increase of static rate. In addition, the growth of the loading rate will inhibit the formation of tensile cracks and promote the development and expansion of shear cracks. The trend of the AE b-value and the RA fractal dimension have a synergistic feature, which can be used as a sudden drop before and after the peak intensity as the failure precursor information of the CPB. The increased static rate will make the CPB reach the dilatancy state in advance, and the changing pattern of dilatancy stress synergizes with the peak strength. The study results provide a theoretical basis for evaluating the structural safety of the CPB.

Rapid fragmentation of Thwaites Eastern Ice Shelf

Abstract. Ice shelves play a key role in the dynamics of marine ice sheets by buttressing grounded ice and limiting rates of ice flux to the oceans. In response to recent climatic and oceanic change, ice shelves fringing the West Antarctic Ice Sheet (WAIS) have begun to fragment and retreat, with major implications for ice-sheet stability. Here, we focus on the Thwaites Eastern Ice Shelf (TEIS), the remaining pinned floating extension of Thwaites Glacier. We show that TEIS has undergone a process of fragmentation in the last 5 years, including brittle failure along a major shear zone, formation of tensile cracks on the main body of the shelf, and a release of tabular bergs on both the eastern and western flanks. Simulations with the Helsinki Discrete Element Model (HiDEM) show that this pattern of failure is associated with high backstress from a submarine pinning point at the distal edge of the shelf. We show that a significant zone of shear, upstream of the main pinning point, developed in response to the rapid acceleration of the shelf between 2002 and 2006, seeding damage on the shelf. Subsequently, basal melting and positive feedback between damage and strain rates weakened TEIS, allowing damage to accumulate. Thus, although backstress on TEIS has likely diminished over time as the pinning point shrunk, accumulation of damage has ensured that the ice in the shear zone remained the weakest link in the system. Experiments with the BISICLES ice-sheet model indicate that additional damage to or unpinning of TEIS is unlikely to trigger significantly increased ice loss from WAIS, but the calving response to the loss of TEIS remains highly uncertain. It is widely recognised that ice-shelf fragmentation and collapse can be triggered by hydrofracturing and/or unpinning from ice-shelf margins or grounding points. Our results indicate a third mechanism, backstress triggered failure, that can occur if and when an ice shelf is no longer able to withstand stress imposed by pinning points. In most circumstances, pinning points are essential for ice-shelf stability, but as ice shelves thin and weaken, the concentration of backstress in damaged ice upstream of a pinning point may provide the seeds of their demise.

Dynamic Response and Failure Process of a Counter-Bedding Rock Slope under Strong Earthquake Conditions

There are massive landslides and potential landslides along the Three Rivers Basin in the Qinghai–Tibet Plateau, which pose a serious threat to the Sichuan–Tibet Railway. A normal shaking table model test was conducted to study the dynamic characteristics and dynamic response of a symmetrical counter-bedding rock slope based on the Zongrong Village landslide. The influences of the dynamic parameters, seismic wave type, and a weak intercalated layer on the slope’s dynamic response were considered. The results showed symmetry between the growth trend of the acceleration amplification factor and other research results. When the input wave amplitude was constant, the acceleration amplification factor increased at first and then decreased as the frequency increased. When the input frequency was near the slope’s natural frequency, the acceleration amplification factor increased at first and then decreased with an increase in the input amplitude and reached the maximum value at 0.3 g. The acceleration amplification factor increased linearly with height in the vertical direction inside the slope but increased slowly at first and then sharply along the slope surface, reaching the maximum value at the slope’s top and exhibiting an obvious “elevation effect”. When sinusoidal waves, Wolong waves, and Maoxian waves with the same amplitude were input, the slope’s amplification effect on the bedrock wave was more obvious. The weak intercalated layer showed the phenomenon of “thin layer amplification” and “thick layer attenuation” in response to the input seismic wave. The slope’s failure process can be roughly divided into three stages: (1) the formation of tensile cracks at the top and shear cracks at the toe; (2) the extension of cracks and the sliding of the slope-surface block; (3) the formation of the main sliding surface.

A meso-mechanical approach to time-dependent deformation and fracturing of partially saturated sandstone

In the present paper, we investigate how water acts to weaken rock in two complementary ways: mechanically through the generalized effective stress principle, and chemically through time-dependent rock-fluid reactions that allow subcritical crack growth. These processes, together with capillary suction and stress corrosion , were incorporated into a three-dimensional discrete element grain-based model to investigate both the time-independent and the time-dependent mechanical behavior of partially saturated sandstone at the mesoscale . The capillary parameters related to capillary suction and subcritical parameters related to stress corrosion in the model were calibrated to match the deformation behavior of partially saturated sandstone observed in laboratory. Following this calibration, numerical simulations of partially saturated sandstone with different levels of saturation were performed in uniaxial compression. The simulations show that both the peak strength and elastic modulus of the sandstone decrease as a function of increasing saturation and that the relationships between these properties can be expressed by negative exponential functions. The simulations are in good agreement with the experimental results. Second, the long-term brittle deformation of partially saturated sandstone with different levels of saturation under a constant stress level was modeled. The results show that time-to-failure during brittle creep decreases, and the initial strain and the minimum creep strain rate increases, as a function of increasing saturation, as also observed in laboratory. The simulations also highlight the formation of tensile cracks as the main deformation mechanism during brittle creep. Finally, brittle creep in partially saturated sandstone samples with different levels of saturation was studied under different stress levels. These simulations show that the minimum creep strain rate and the time-to-failure as a function of stress can be well described by exponential relations. We conclude that the proposed model permits a deeper understanding of time-independent and time-dependent deformation and failure of partially saturated sandstone at the mesoscale.

Propagation of stress wave and fragmentation characteristics of gangue-containing coal subjected to water jets

Water jet technology has been broadly applied to extract coalbed methane (CBM) from low permeability reservoirs. However, the existing studies on the failure and damage characteristics of coal subjected to water jets have neglected the influence of gangue. To study the propagation of stress waves and the fragmentation characteristics of gangue-containing coal impacted by a water jet, a numerical model was developed for gangue- and defect-containing coal based on the smooth particle hydrodynamics (SPH) method, and was verified by using laboratory experiments. The research results indicated that gangue had a significant influence on the propagation of stress waves and the fragmentation characteristics of coal. When the stress wave propagated from coal to gangue, the total reflective and transmissive regions of the stress wave existed at the interface. The interaction process of stress waves reflected and transmitted at the interface led to the formation of shear cracks near the liquid–solid contact region and the formation of tensile cracks in the other regions, which eventually formed the obvious local fragmentation characteristics. Finally, the blocking coefficient M was defined to quantify the resistance of the gangue against the stress-wave propagation. The resistance of the gangue against the stress-wave propagation was uneven, and the maximum and minimum blocking coefficients were 0.48 and 0.15, respectively. This study could lay a foundation for understanding the breaking mechanism of coal by water jets.

Numerical investigation of the cyclic performance of reinforced concrete frames equipped with a combination of a rubber core and a U-shaped metallic damper

This paper proposes a seismic resisting technique for reinforced concrete frame buildings that uses a combination of a rubber core and a U-shaped friction damping system. The U-shaped elements are made from steel and aluminum while the core is made of rubber. The elastoplastic model is used to define steel and aluminum; the hyper-elastic, Ogden model is used to define the rubber material. The system under consideration is a hybrid damper that works through a steel wall. To evaluate the effectiveness of the proposed damper system, a full-scale cyclic analysis on a reinforced concrete frame (RC was performed. The RC frame showed pinched behavior, whereas the hysteresis curves of the strengthened frames were more stable. This was because the activation of the friction damper which formed a larger loop area. The results showed that the pattern of tensile crack formation in the model with and without the damper system was not changed significantly, but the maximum shear strength, stiffness, and energy dissipation capacities were significantly improved.

Tensile response and fracturing process in moderate- and high-plasticity clays

Sinkholes in clay soils can be considered as the collapse of a soil layer previously bridging a void. Here, flexural deformation in the clay drives the formation of tensile cracks from the lowest surface of the layer and the consequent soil collapse is from crack propagation. Considering a simplified model of the sinkhole geometry, this paper aims to describe the tensile and fracture behaviour of clay soils with different plasticity indices. Speswhite kaolin, London, and Durham clays were tested using direct tensile and bending tests. Moderate- and high-plasticity clays showed a nonlinear fracture response with increasing moisture content, while low-plasticity clays demonstrated a linear response. Bending tests confirmed the importance of the moisture content while the plasticity index confirmed the difference in ductile or fragile collapse for fracture propagation. To assess the results, elasto-plastic fracture mechanics (EPFM) theory was applied to clays with appropriate modifications. The analysis demonstrated that EPFM theory provides a good baseline for predicting tensile fracture behaviour in clay soils, which can be extended in future research.

Thermal cycling induced stress–assisted sigma phase formation in super duplex stainless steel

Thermal cycling induced the phase transformation originated from the physical simulation of power plant on/off operation. The effect of thermal cycling on duplex stainless steel was studied to understand its phase transformation comprehensively. Cyclic thermal processing is a nonisothermal heat treatment method known to accelerate the kinetics of phase transformation. In this study, when the number of thermal cycles increased, the ferrite grains gradually contracted from the grain boundaries and finally disappeared due to the eutectoid reaction. However, the austenite phase demonstrated a parabolic increase and the intermetallic sigma (σ) phase, formed at the grain boundaries, exhibited a similar trend. The KAM maps reveal the highest degree of misorientation (up to 2°) may have either been at the γ′ or σ phase at 40 and 80cycles. In DSS, the misorientations (>15°) among grains also affect σ formation. A high crystallographic misorientation between the austenite and ferrite phases favored σ precipitation. The calculated thermal stress of 422MPa assisted the σ formation by reducing the activation energy and accelerating the alloying element diffusion. The σ phase formation caused by thermal cycling increased the yield strength and ultimate strength but degraded ductility. The formation of tensile cracks was related to the σ phase at the interface or the σ matrix.

THE USE OF NONLOCAL CRITERIA IN FORECASTING FRACTURE OF QUASI-BRITTLE MATERIAL WITH A HOLE UNDER COMPRESSION

The study is aimed at the development of the new failure criteria for quasi-brittle materials in conditions of stress concentration. The possibility of using non-local failure criteria for description of the brittle, quasi-brittle and ductile fracture of the materials with notches is analyzed. The general feature of these criteria consists in the introduction of the internal dimension characterizing the structure of the material, which provides the possibility of describing a large-scale effect in conditions of the stress concentration and thereby expand the area of their application compared to traditional criteria though it is limited to the cases of brittle or quasi-brittle fracture with a small pre-ffacture zone. To broaden the scope of their application to quasi-brittle fracture with a developed pre-fracture zone we propose to abandon the hypothesis about the size of the pre-fracture zone as a constant related only to the structure of the material. A number of the new nonlocal criteria, which are the development of the criteria of the mean stress and fictitious crack, are developed, substantiated from the physical standpoint, and proved experimentally. These criteria contain a complex parameter characterizing the size of the pre-fracture zone and taking into account not only the structure, but also the ductile properties of the material, specimen geometry and loading conditions. The expressions for the critical pressure in the problem of tensile crack formation upon compression of the samples of geomaterials with a circular hole are derived. The results of calculations match rather well the experimental data on the destruction of drilled gypsum slabs.

Effect of thermal treatments in high purity Ar on the oxidation and tribological behavior of arc-PVD c-Al0.66Ti0.33N coatings

The effect of temperature in high purity Ar (low oxygen partial pressure) on the oxidation and crystal phase evolution of c-Al0.66Ti0.33N arc-PVD coatings was investigated. High temperature tribology in Ar jet and adhesion behavior of the oxidized coating were addressed. The use of Ar protects the coating from the oxidation reactions and allowed to shed light into the details and paths of the nitride oxidation process. The c-Al0.66Ti0.33N nitrides were slightly oxidized in Ar even at high temperature (700 to 900 °C). The surface chemistry evaluation shows very thin Al- and Ti-based oxide layers formation after treatment at 700 °C in Ar. However, the onset formation of the rutile TiO2 oxide was detected only after treatment at 900 °C and was clearly found by low-angle XRD diffraction after 1000 °C. The XPS surface analysis of the oxidized samples at 800 °C indicated the formation of extremely thin layers mainly composed of mixed oxides (α-Al2O3 γ-Al2O3 and rutile TiO2). The gradual changes in the chemical composition of the oxidized coatings observed at 900 °C clearly demonstrate the formation of gradient boundaries between Al-rich and Ti-rich oxy-nitride layers. After exposure at 1000 °C at least four oxides and oxi-nitrides layers and interlayers were found. Additionally, it is suspected that the transition oxide phases such as c-TiO, c-Al0.54Ti2.46O0.28N4.58, α-Al2TiO5 and TiOxNy might be precursors leading to the formation of thermodynamically stable rutile and alumina phases. Surface inspection after high temperature tribology in Ar jet showed formation of tensile cracks in the wear tracks and wear processes due to high size particle adhesion-abrasion and low size particle micro-ploughing of hard nitrides, oxi-nitrides and brittle oxide particles. Adhesion tests performed after high temperature tribology in Ar showed critical load decrease related to cohesive and adhesive damages at the contact point of the scratch track.

Ductile-Brittle Transition in Geomaterials, Caused by Tensile Stress Concentration

The possibility of using known nonlocal and stress gradient fracture criteria to describe brittle, quasi-brittle, and ductile fracture of materials with openings is analyzed. A common property of these criteria is the introduction of intrinsic material length characterizing its structure, which allows one to describe the size effect in conditions of stress concentration. At the same time, the scope of application of nonlocal criteria is limited to cases of brittle or quasi-brittle fracture with a small fracture process zone. To expand the scope of application, new fracture criteria are proposed, which are the development of the average stress criterion, and the stress gradient criterion, and which contain a complex parameter that characterizes the size of the fracture process zone and accounts not only for the material structure, but also plastic properties of the material, geometry of the sample, and its loading conditions. Expressions are obtained for the critical pressure in the problem of the formation of tensile cracks under compression in the samples of geomaterials with a circular hole. The calculation results are in good agreement with the experimental data on the fracture of drilled gypsum plates.

Nonlocal Criteria for Brittle and Quasi-Brittle Fracture of Geomaterials and Rocks

Nonlocal criteria are used for prediction materials and rock mass failure near stress concentrations (pores, faults, openings, excavations). A common property of nonlocal fracture criteria is the introduction of the intrinsic material length characterizing its microstructure, which allows one to describe the size effect in conditions of stress concentration. At the same time the scope of their application is limited to cases of brittle or quasi-brittle fracture with a small fracture process zone. To expand the scope of the criteria for cases of fracture with a developed fracture process zone, it is proposed to abandon the hypothesis of the size of this zone as a material constant, associated only with the material structure. New fracture criteria are proposed, which are the development of the average stress criterion, and point stress criterion, and which contain a complex parameter that characterizes the size of the fracture process zone and accounts not only for the material structure, but also plastic properties of the material, geometry of the sample, and its loading conditions. Expressions are obtained for the critical pressure in the problem of the formation of tensile cracks under compression in the samples of geomaterials with a circular hole. The calculation results are in good agreement with the experimental data on the fracture of drilled gypsum plates.

Long-Term Oxidation Testing and Lifetime Modeling of Cast and ODS FeCrAl Alloys

Long-term cyclic oxidation testing was conducted on oxide dispersion strengthened (ODS) and cast FeCrAlY alloys at 1100 and 1200 °C with 1 or 100 h hold time in air, O2, and humid atmospheres. These data were used to optimize four different cyclic oxidation models and calculate the Al consumption rate due to oxidation. The pkp and COSIM-GSA models were able to reproduce accurately the experimental oxidation curves, and lifetime predictions based on these models were in good agreement with experiments. Microstructure characterization revealed that the degradation of the ODS FeCrAlY cyclic oxidation performance was mainly due to the incorporation of Ti carbonitrides in the alumina scale and the formation of tensile cracks. Controlling the levels of C, N, and S in one ODS alloy resulted in oxidation performance only moderately lower than the performance of cast FeCrAlY alloys. A few, very deep, tensile cracks formed at the cast alloy surface upon thermal cycling. Finally, the effect of specimen mechanical strength and the presence of H2O on ODS FeCrAl durability are discussed.

Effects of Iron-Rich Intermetallics on Tensile Deformation of Al-Cu 206 Cast Alloys

An investigation has been carried out of the influence of iron on the tensile properties and fracture behavior of a series of Al-Cu 206 cast alloys. Iron contents are explored from 0.15 to 0.5 wt pct, and at two levels of silicon and manganese. The types, morphologies and quantities of the various iron-rich intermetallics are characterized metallographically, and their effects on the tensile properties and the nucleation and growth of cracks during tensile deformation are studied. In addition, oxide films are shown to play an important role in both the nucleation of the iron-rich intermetallics and the formation of tensile cracks.

Computational and experimental study of the fracture of a brittle material with an elliptical notch under compression

This paper presents a theoretical and experimental study of the formation of tensile cracks in a brittle geomaterial with an elliptical notch under compression with variation in the angle of inclination of the notch to the loading axis. Calculation results are compared with the experimental data obtained.

Evaluation of Tensile Strength-Strain Characteristics of Fiber-Reinforced Soil through Laboratory Tests

AbstractTension cracking is a very important phenomenon in the case of compacted fine grained soils, which are commonly used in earth dams, embankments, and waste containment systems. The strength and permeability of earthen structures can be seriously affected by the formation of tensile cracks. The purpose of this paper is to evaluate the effect of discrete and randomly distributed fibers (DRDF) in improving the tensile strength-strain characteristics of bentonite amended natural silty soil. The authors conducted a series of direct tensile tests on unreinforced and fiber-reinforced soil by using a specially developed tensile test set up in the laboratory. They conducted tests by varying the fiber content and fiber length and studying their effect on tensile strength-strain characteristics and crack formation. The present paper indicates that the blending of fibers improved the tensile strength-strain characteristics and ductility of the soil. The authors carried out a digital image cross-correlation (DI...