scholarly journals Contribution of root tensile of Pennisetum polystachion on shear strength of sandy soil in slope bio-engineering technique

2021 ◽  
Vol 42 (3(SI)) ◽  
pp. 857-864
Author(s):  
Z.A. Rahman ◽  
◽  
A.E. Ettbeb ◽  
W.M.R. Idris ◽  
S.N.A. Tarmidzi ◽  
...  
Keyword(s):  
Shear Strength ◽  
Sandy Soil ◽  
Slope Failure ◽  
Tensile Force ◽  
Root Diameter ◽  
Slope Instability ◽  
Strength Parameter ◽  
Experimental Program ◽  
Soil Shear Strength ◽  
Bio Engineering

Aim: In soil bio-engineering, plant has been widely adopted as important material in promoting sustainable ecological function in slope instability measures. Plant canopy provides shelter and at subsurface level, root networking attributes toward stability of soil against erosion and slope failure. To investigate the potential of selected P. polystachion as biological material in soil bio-engineering for improving the soil shear strength of sandy soil planted with P. polystachion. Methodology: The selected species was initially planted using hyroseeding technique on studied plots which facilated with and without fiber netting (made of paddy straw). A control plot was also prepared for reference of this study. The plots were routinely watered twice a day for six months before experimental program was scheduled for determining of root tensile and soil shear strength tests. Results: The root tensile strength of P. polystachion exhibited a positive significant relationship between root tensile force and root diameter. The shear strength of soil was affected by the presence of root if compared to that of soil without root (control). Biomass analysist also agree with the soil water content, ws. High biomass contributed to the increase in the values of soil shear strength parameter of cohesive, c and angle of friction, q for root-permeated soil with P. polystachion. Interpretation: This study has suggested that the potential application of this selected species for slope vegetation in improving the erosion control and slope stability in soil-bioengineering scheme.

scholarly journals Root Tensile Resistance of Selected Pennisetum Species and Shear Strength of Root-Permeated Soil

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Afaff Emhemed Ettbeb ◽  
Zulfahmi Ali Rahman ◽  
Wan Mohd Razi Idris ◽  
Jumaat Adam ◽  
S. Abd. Rahim ◽  
...  
Keyword(s):  
Shear Stress ◽  
Shear Strength ◽  
Tensile Force ◽  
Mineral Fertilizer ◽  
Tensile Tests ◽  
Root Diameter ◽  
Slope Instability ◽  
Root Reinforcement ◽  
Significant Relationships ◽  
Peak Shear Stress

It is widely recognized that vegetation plays a significant role in contrasting slope instability through the root reinforcement. The main objectives of this paper are to evaluate the root tensile of selected Pennisetum species, namely, P. pedicellatum (PPd) and P. polystachion (PPl), and to determine the soil shear strength of root-permeated soil from these species. The selected species were initially planted in the polybags using the hydroseeding technique. A mineral fertilizer of NPK ratio 10 : 8 : 10 was adopted in the hydroseeding mixture. Routine watering program was applied twice a day throughout growth observation for six months. Four replications were prepared for each species including a set of control polybags, which contained only soil for reference and comparison. The results of root tensile tests revealed the significant relationships between root diameter and tensile force. In comparison, the PPl was still indicated by higher values of root tensile force than PPd. The presence of roots clearly has contributed to the shear stress of root-permeated soils. The root density based on root biomass measurement attributed to the higher value of peak shear stress as achieved by PPl than PPd. The combined effects of root tensile and the soil shear strengths of this selected species can be used as biological materials in slope protection against erosion.

scholarly journals A Determination Method of Rainfall Type Based on Rainfall-Induced Slope Instability

2021 ◽  
Author(s):  
Yafen ZHANG ◽  
Yulong ZHU ◽  
Xiaoyu YAN ◽  
Shu LI ◽  
Qijing YU ◽  
...  
Keyword(s):  
Shear Strength ◽  
Slope Failure ◽  
Slope Instability ◽  
Determination Method ◽  
Shear Strength Parameters ◽  
Strength Parameters ◽  
Failure Initiation ◽  
Soil Shear Strength ◽  
Rainfall Type

Abstract This work presents a determination method of rainfall types based on rainfall-induced slope instability to eliminate the current dilemma of the inconsistent classification of rainfall types. Firstly, 5,808 scenarios of slope instability are simulated with 11 kinds of soil properties under 528 designed intensity-duration (I−D) conditions. Then through analysis of the I−D conditions when slope failure occurred, rainfall is classified into two types: short-duration − high-intensity (SH) type, and long-duration − low-intensity (LL) type. According to the analysis results, it indicates that rainfall types affect the initiation of slope failure, i.e., different I−D conditions will affect the slope failure initiation under LL type rainfall, while the slope failure initiation will not be affected by the change of I−D conditions under SH type rainfall. In addition, the results show that the classification of rainfall types does not depend on the soil shear strength parameters (cohesion and internal friction angle), although the change of soil shear strength parameters will cause the shift of threshold curve of slope failure in the I−D conditions two-dimensional (2D) plane. The findings in this study benefit to understanding the effect of rainfall type on the mechanism of slope failure initiation, which will promote the development of an early warning system of slope failure in the future by considering the identification of rainfall types.

scholarly journals SOIL SHEAR STRENGTH PARAMETER ANALYSIS BASED ON BEHAVIOR ANALYSIS OF LANDSLIDE CASE

UKaRsT ◽  
2020 ◽  
Vol 4 (2) ◽  
pp. 163
Author(s):  
Dyah Wahyu Apriani ◽  
Umar Mustofa ◽  
Rachmad Hidayat
Keyword(s):  
Shear Strength ◽  
Internal Friction ◽  
Slope Failure ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Unit Weight ◽  
Strength Parameter ◽  
Soil Parameters ◽  
Soil Shear Strength ◽  
Reverse Analysis

Slope failure is a complex event. It can provide useful information about the condition of soil parameters on the failed slope in the same way it can provide an opportunity to evaluate the stability of other slopes. To evaluate the occurence of slope failure, unit weight data and shear strength properties of soil are needed, as well as methods of analysis including failure mechanisms. One of the methods used to evaluate landslide events is reverse analysis. In this study, reverse analysis was carried out on landslides that occurred on the slopes of D-D 'and F-F' at the Integrated Campus Building of the Institut Teknologi Kalimantan. The finite element method is used to analyze the safety number of the slopes under review. From the results of the reverse analysis, it was obtained that the soil parameters at the time of collapse in the top layer resulted in the value of unit weight (γ) = 20 kN / m2, Cohesion (c) = 2 kPa and Internal friction angle (φ) = 27 ° . Slope failure occured due to an increase in soil volume weight value, as well as a decrease in soil shear strength parameters, namely cohesion and internal friction angle.

scholarly journals Spatio-Temporal Dynamic Architecture of Living Brush Mattress: Root System and Soil Shear Strength in Riverbanks

Forests ◽  
2018 ◽  
Vol 9 (8) ◽  
pp. 493 ◽  
Author(s):  
Dong Zhang ◽  
Jinhua Cheng ◽  
Ying Liu ◽  
Hongjiang Zhang ◽  
Lan Ma ◽  
...  
Keyword(s):  
Shear Strength ◽  
Root Morphology ◽  
Spatial Scales ◽  
Root Diameter ◽  
Slope Position ◽  
Protective Effects ◽  
Salix Alba ◽  
Ecological Protection ◽  
Soil Shear Strength ◽  
Spatio Temporal

As a basal measure of soil bioengineering, the living brush mattress has been widely applied in riparian ecological protection forest construction. The living brush mattress shows favorable protective effects on riverbanks. However, there are few reports on the root structure and the soil strengthening benefit of the living brush mattress. The present work reports a series of experiments on root morphology and soil shear strength enhancement at the temporal and spatial scales. The object of the study is 24 living brush mattress trees constructed with Salix alba L. ‘Tristis’ (LBS hereafter). Traditional root morphology and mechanical measurement methods were used to collect the parameters. The results showed that the root systems of LBS had the characteristics of symmetry and upslope growth. The roots were mainly distributed in a cylindrical region of the soil (radius × thickness: 0.4 m × 0.5 m) and their biomass increased with different growth rates for the periods from 1 to 5 and from 5 to 7 years. Both age and slope position were factors that influence root growth. The root diameter falls within 0–5 mm, has a significant effect on the soil shear strength and provides a conical-shape potentiation zone to ensure the efficient protection of a riverbank. The results of this study demonstrate that LBS is an efficient and feasible engineering measure in the field of riverbank protection.

scholarly journals Numerical Analysis of Soil Slope Stabilization by Soil Nailing Technique

2019 ◽  
Vol 9 (4) ◽  
pp. 4469-4473
Author(s):  
D. A. Mangnejo ◽  
S. J. Oad ◽  
S. A. Kalhoro ◽  
S. Ahmed ◽  
F. H. Laghari ◽  
...  
Keyword(s):  
Factor Of Safety ◽  
Slope Failure ◽  
Limit Equilibrium ◽  
Slope Instability ◽  
Soil Nailing ◽  
Soil Slope ◽  
Prevention Measures ◽  
Soil Nail ◽  
Soil Shear Strength ◽  
Nail Diameter

Slope instability may be a result of change in stress conditions, rise in groundwater table and rainfall. Similarly, many slopes that have been stable for several years can abruptly fail due to changes in geometry, weak soil shear strength or as the effect of an external force. Debris flows (i.e. slope failures) take place without any warning and can have devastating results. So, it is vital to understand the slope failure mechanism and adopt safety prevention measures. Soil nailing is one of the widely used stabilization techniques for soil slopes. In this study, soil nail technique is proposed to upgrade the existing slope in clay. A parametric study was conducted to understand the effects of different nail diameter (i.e. 25mm and 40mm) and nail inclination (i.e. 200, 250, 300, 350 and 400) on slope stability. Morgenstern-Price (i.e. limit equilibrium) method was used to determine the factor of safety of the slope. It was found that the factor of safety of the existing slope improved significantly with three rows of 40mm diameter nail at an inclination of 400.

Rate of strength increase of unsaturated lateritic soil

2008 ◽  
Vol 45 (9) ◽  
pp. 1335-1343 ◽  
Author(s):  
Meen-Wah Gui ◽  
Chun-Ming Yu
Keyword(s):  
Shear Strength ◽  
Failure Criterion ◽  
Matric Suction ◽  
Slope Instability ◽  
Lateritic Soil ◽  
Strength Increase ◽  
Residual Soil ◽  
Strength Tests ◽  
Soil Shear Strength ◽  
Intact Soil

Lateritic soil is a kind of residual soil that is widely distributed in Asia. The water table of the soil is normally very deep so the upper part of the soil is often unsaturated. The largest lateritic soil area in Taiwan is the Linkou terrace. Because the soil here is loosely cohered and consolidated, the problem of slope instability and landslides has always been a major concern. To evaluate the triggering mechanism of landslides, it is necessary to obtain the failure criterion that represents both the saturated and unsaturated conditions of the soil before any analysis is carried out. The parameter required to define such a failure criterion is the rate of shear strength increase, tan φb, which can be obtained via a series of laboratory strength tests in a modified triaxial system under various matric suction levels. Both the intact and remolded lateritic soils taken from Linkou terrace have been tested for this purpose. The results confirm that matric suction in the lateritic soil contributes significantly to the soil shear strength and that intact soil has a higher strength than remolded soil.

scholarly journals Analisis Pengaruh Fluktuasi Muka Air Waduk terhadap Stabilitas Lereng Waduk Dengan Menggunakan Program Plaxis 2D

2019 ◽  
Vol 24 (2) ◽  
pp. 113
Author(s):  
Paravita Sri Wulandari ◽  
Daniel Tjandra
Keyword(s):  
Shear Strength ◽  
Water Content ◽  
Water Level ◽  
Laboratory Tests ◽  
Slope Failure ◽  
Soil Characteristics ◽  
Soil Samples ◽  
Initial Condition ◽  
Soil Shear Strength ◽  
Influence Of Water

Reservoir is needed as a source of water supply to the surrounding populations. The design of a reservoir needs to consider several aspects of soil embankment such as variations in water content and changes in shear soil shear strength and also the influence of water level in reservoir. The purpose of this research is to analyze these three aspects in the design of a reservoir. This research was begun by taking soil samples for embankment and conducting soil tests to obtain soil characteristics at the initial condition. The further laboratory tests were conducted to determine the effect of changes in water content on the shear strength of the soil. The variation of soil embankment characteristic was then modeled by Plaxis 2D program to obtain the effect of changes in soil embankment characteristic and fluctuation of the water level in the reservoir. The results showed that the increase in water content significantly decrease the shear strength of the soil. The changes of soil shear strength affect the pattern of slope failure and safety factor. In addition, the pattern and direction of the slope failure were also influenced by the water level of the reservoir.

scholarly journals Mechanical Behaviour of Reinforced Sand with Natural Curauá Fibers through Full Scale Direct Shear Tests

2019 ◽  
Vol 92 ◽  
pp. 12003
Author(s):  
Leila Maria Coelho de Carvalho ◽  
Michelé Dal Toé Casagrande
Keyword(s):  
Shear Strength ◽  
Sandy Soil ◽  
Soil Reinforcement ◽  
Direct Shear ◽  
Shear Strength Parameters ◽  
Shear Tests ◽  
Strength Parameters ◽  
Direct Shear Tests ◽  
Soil Shear Strength ◽  
Curaua Fibers

Inclusion of natural fibers (sisal, curauá, coco fiber and others) for soil improvement has been the study object in diverse geotechnical areas and it is a topic of growing interest, within the research area of new geotechnical materials. The state of the art in this subject highlights excellent results as soil strength parameters improve and post-cracking strength (toughness) increase. Soil reinforcement technique with fibers is established in the technology of composite materials, this being a combination of two or more materials presenting properties that the component materials do not possess on their own. The aim of this paper is to study the mechanical behaviour of sand-fiber composite by inserting natural curauá fibers into a sandy matrix, with different fiber contents. The fibers were randomly distributed in the soil mass. The experimental program included physical and mechanical characterization of the composites, using full-scale direct shear tests, with samples measuring 30 x 30 cm and 15 cm high. Direct shear tests were carried out using fibers with 25 mm length and 0.5 and 0.75% fiber content (relative to the soil dry weight). The specimens also presented a relative density of 50% and moisture content of 10%. It was sought to establish a pattern behaviour so that the addition of curauá fiber influence can be explained, thus, comparing with the sandy soil shear strength parameters. Inclusion of natural curauá fibers as soil reinforcement presented satisfactory results, as an increase in the soil shear strength parameters was observed when compared with sandy soil results.

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