Strength Behavior of Fine Grained Soil Reinforced with Randomly Distributed Polypropylene Fibers

Current research main aim is to study the effect of adding polypropylene fiber (PPF) on the behavior of expansive soil to reduce the swelling as percentage (0.5, 1 and 2%) of the weight of dry soil. Expansive soil used in this research was prepared artificially by mixing Ca-based bentonite from geological survey and mining company with sandy soil brought from Karbala city as percentage 80% bentonite to 20% sand of dry weight. Multiple laboratory tests have been carried are (Unconfined Compression Test, One-Dimensional Consolidation Test, Swelling Test, Sieve Analysis and Cycle Swell Shrink Test). A conventional odometer cell was modified to allow the study of swell- shrink cycle test to be carried out under controlled temperatures and surcharge pressure. The results showed that the increase in percentage of (PPF) led to decrease the swelling and to increase the unconfined compression strength. The wetting and drying results of (PPF) showed that with continuous cycles the effect of (PPF) keeps on reducing the swelling and the 2% of (PPF) produces less ratio of swell - shrink, which has obtained higher than 57 % in the improvement factor of swell and shrink.

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“…The shear failure occurred after a long time from the appearance of the crack. These results similar to the results obtained by the [15,27,28].…”

Section: Results Of Unconfined Compression Testsupporting

confidence: 91%

Stabilization of Expansive Soils Using Polypropylene Fiber

Hussein

Ali

2019

Civ Eng J

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“…A number of workers have added fibres to pre-moisture conditioned soils, using hand mixing to ensure sufficient mixing in terms of both distribution and orientation (AlWahab and Al-Qurna, 1995;Li, 2005;Freitag, 1986;Zaimoglu and Yetimoglu, 2011). In all cases the individual fibres clumped and matted to form fibrous balls that had to subsequently be prised apart and redispersed in the soil mass.…”

Section: 2mentioning

confidence: 99%

“…A search of the literature showed that testing has typically been done utilising fibre contents of 0·05-1·25%, with a small number of tests having been conducted using higher contents of around 3-5%, although with difficulty (Al-Wahab and Al-Qurna, 1995;Al-Wahab and Heckel, 1995;Amir-Faryar and Aggour, 2012;Anagnostopoulos et al, 2014;Cai et al, 2006;Chegenizadeh and Nikraz, 2011;Estabragh et al, 2012;Fowmes et al, 2006;Freitag, 1986;Zaimoglu and Yetimoglu, 2011). In the initial compaction tests done in this study, fibre contents of 0·25% and 0·75% were used in order to obtain values at the lower and higher ends of the range.…”

Section: Laboratory Testingmentioning

confidence: 99%

Mixing and compaction of fibre- and lime-modified cohesive soil

Gelder

Fowmes

2016

Proceedings of the Institution of Civil Engineers - Ground Impr

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Citation: GELDER, C. and FOWMES, G.J., 2015. Mixing and compaction of fibre-and lime-modified cohesive soil.Proceedings of the ICE -Ground Improvement, 169 (2), pp. 98-108.Additional Information:• Fibre reinforcement is a versatile method of increasing the shear strength of soils for earthwork applications. However, research to date has encountered a number of problems when utilising cohesive host soils. The aim of this study was to develop a suitable site-applicable method of mixing fibre into cohesive host soils. Intermediate plasticity clay reinforced with monofilament polypropylene fibres was used in the laboratory investigations. In order to mix the fibres successfully, the initial moisture content of the host soil was increased prior to the introduction of fibres. By introducing quicklime, excess moisture was removed through the hydration process, and a portion of free water was effectively held within aggregations of flocculated clay particles, thereby having little influence on the dynamic boundaries. Fibrous inclusions within the clay clods resisted compactive effort, forming an interlocked structure. As a result, the optimum moisture content increased and the maximum dry density decreased. This trend was heavily dependent on the interfacial shear resistance along the fibre boundary, which consequently decreased as the water content increased or the compactive effort was increased. Results from strength tests confirmed that both peak and post-peak shear strength increased, creating a more ductile material capable of maintaining shear strength at high levels of strain.

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“…Continuum approaches involve laboratory tests of or numerical simulations of representative elements of rooted soil, with the strength being represented as a Mohr-Coulomb failure envelope or yield surface, as conventionally used for non-vegetated soil, like fibre-reinforced sands (e.g. Michalowski and Čermák 2003;Zaimoglu and Yetimoglu 2012;Wood et al 2016). This approach is convenient where the dimensions and spacing of the reinforcement are small and behaviour can be homogenised statistically; otherwise, tests are difficult to perform, time consuming and expensive.…”

Section: Introductionmentioning

confidence: 99%

A critical evaluation of predictive models for rooted soil strength with application to predicting the seismic deformation of rooted slopes

et al. 2019

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This paper presents a comparative study of three different classes of model for estimating the reinforcing effect of plant roots in soil, namely (i) fibre pull-out model, (ii) fibre break models (including Wu and Waldron's Model (WWM) and the Fibre Bundle Model (FBM)) and (iii) beam bending or p-y models (specifically Beam on a Non-linear Winkler-Foundation (BNWF) models). Firstly, the prediction model of root reinforcement based on pull-out being the dominant mechanism for different potential slip plane depths was proposed. The resulting root reinforcement calculated were then compared with those derived from the other two types of models. The estimated rooted soil strength distributions were then incorporated within a fully dynamic, plane-strain continuum finite element model to assess the consequences of the selection of rooted soil strength model on the global seismic stability of a vegetated slope (assessed via accumulated slip during earthquake shaking). For the particular case considered in this paper (no roots were observed to have broken after shearing), root cohesion predicted by the pull-out model is much closer to that the BNWF model, but is largely over-predicted by the family of fibre break models. In terms of the effects on the stability of vegetated slopes, there exists a threshold value beyond which the position of the critical slip plane would bypass the rooted zones, rather than passing through them. Further increase of root cohesion beyond this value has minimal effect on the global slope behaviour. This implies that significantly over-predicted root cohesion from fibre break models when used to model roots with non-negligible bending stiffness may still provide a reasonable prediction of overall behaviour, so long as the critical failure mechanism is already bypassing the root-reinforced zones.

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Strength Behavior of Fine Grained Soil Reinforced with Randomly Distributed Polypropylene Fibers

Cited by 68 publications

References 16 publications

Stabilization of Expansive Soils Using Polypropylene Fiber

Stabilization of Expansive Soils Using Polypropylene Fiber

Mixing and compaction of fibre- and lime-modified cohesive soil

A critical evaluation of predictive models for rooted soil strength with application to predicting the seismic deformation of rooted slopes

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