scholarly journals Slope instability in relation to timber harvesting in the Chilliwack Provincial Forest

1975 ◽  
Vol 51 (2) ◽  
pp. 59-63 ◽  
Author(s):  
T. M. Ballard ◽  
R. P. Willington
Keyword(s):  
Shear Strength ◽  
Sedimentary Rock ◽  
Road Construction ◽  
Timber Harvesting ◽  
Slope Instability ◽  
Site Conditions ◽  
Slope Failures ◽  
Stability Problems ◽  
Soil Shear Strength ◽  
Specific Factors

Slope instability problems in the Chilliwack Forest are particularly prominent in areas of sedimentary rock and where very steep glaciated slopes persist. Increased frequency of slope failures often appears related to recent logging and road construction. Specific factors contributing to instability can be analyzed by interpreting site conditions in relation to soil shear strength and stress equations. Such analysis can be applied in planning roads and harvesting to minimize stability problems.

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 Kuat Geser Tanah Lempung menggunakan Kapur dan Petrasoil

2020 ◽  
Vol 8 (1) ◽  
pp. 64-68
Author(s):  
Indrayani Indrayani .
Keyword(s):  
Shear Strength ◽  
Soil Compaction ◽  
Road Construction ◽  
Clay Soils ◽  
Strength Testing ◽  
Test Results ◽  
Index Properties ◽  
Lime Water ◽  
Soil Shear Strength ◽  
Construction Works

Several studies have added lime, fly ash, or gypsum to clay soils to increase the shear strength of relatively low clay soils. The addition of lime and petrasoil as solvents in water was carried out in this study, where petrsoil is often used in Indonesian road construction works. This study aims to obtain the effect of adding lime and petrasoil to the shear strength of clay. The tests consists of the index properties, seive analysis, atterberg limits, soil compaction, and shear strength testing, based on SNI and ASTM. Mixed variations consist of 6, namely: (i) soil + petrasoil; (ii) soil + 10% lime + petrasoil; (iii) soil + 15% lime + petrasoil; (iv) soil + 20% lime + petrasoil; (v) soil + 10% lime + water; (vi) soil + water; all variations without ripening. The test results showed an increase in the value of soil cohesion in the addition of petrasoil and lime variations of 20%, amounting to 50.94. While the angle of shear of the soil increased with the addition of lime at a variation of 10% both with water and with petrasoil, which amounted to 35.10. This shows an increase in soil shear strength with the addition of petrasoil and lime to the soil.

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 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.

Finite Element Modeling of a Mechanically Stabilized Earth Trial Wall

2021 ◽  
pp. 036119812110164
Author(s):  
Andrew Lees ◽  
Michael Dobie
Keyword(s):  
Finite Element ◽  
Shear Strength ◽  
Retaining Wall ◽  
Back Analysis ◽  
Soil Parameters ◽  
Failure Behavior ◽  
Valuable Insight ◽  
Deformation And Failure ◽  
First Case ◽  
Soil Shear Strength

Polymer geogrid reinforced soil retaining walls have become commonplace, with routine design generally carried out by limiting equilibrium methods. Finite element analysis (FEA) is becoming more widely used to assess the likely deformation behavior of these structures, although in many cases such analyses over-predict deformation compared with monitored structures. Back-analysis of unit tests and instrumented walls improves the techniques and models used in FEA to represent the soil fill, reinforcement and composite behavior caused by the stabilization effect of the geogrid apertures on the soil particles. This composite behavior is most representatively modeled as enhanced soil shear strength. The back-analysis of two test cases provides valuable insight into the benefits of this approach. In the first case, a unit cell was set up such that one side could yield thereby reaching the active earth pressure state. Using FEA a test without geogrid was modeled to help establish appropriate soil parameters. These parameters were then used to back-analyze a test with geogrid present. Simply using the tensile properties of the geogrid over-predicted the yield pressure but using an enhanced soil shear strength gave a satisfactory comparison with the measured result. In the second case a trial retaining wall was back-analyzed to investigate both deformation and failure, the failure induced by cutting the geogrid after construction using heated wires. The closest fit to the actual deformation and failure behavior was provided by using enhanced fill shear strength.

Shear Strength Monitoring System Based on Measurement of Shear Wave Velocity and Moisture Content

2014 ◽  
Vol 635-637 ◽  
pp. 750-754
Author(s):  
Peng Hu ◽  
Qing Li ◽  
Yi Wei Xu ◽  
Nan Ying Shentu ◽  
Quan Yuan Peng
Keyword(s):  
Shear Strength ◽  
Moisture Content ◽  
Shear Wave ◽  
Monitoring System ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Bender Elements ◽  
Strength Measurement ◽  
Soil Shear Strength ◽  
The Relationship

Expound the importance of soil shear strength measurement at mudslide hidden point to release the loss caused by the disaster, explain the relationship between shear wave velocity, moisture content and shear strength, design the shear strength monitoring system combining the shear wave velocity measured by Piezoelectric bender elements and moisture content.

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.

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