Field and laboratory study of an unsaturated expansive soil associated with rain-induced slope instability

2003 ◽  
Author(s):  
Liangtong Zhan
Keyword(s):  
Laboratory Study ◽  
Expansive Soil ◽  
Slope Instability ◽  
Unsaturated Expansive Soil

Field study of rainfall infiltration into a grassed unsaturated expansive soil slope

2007 ◽  
Vol 44 (4) ◽  
pp. 392-408 ◽  
Author(s):  
Tony LT Zhan ◽  
Charles WW Ng ◽  
Del G Fredlund
Keyword(s):  
Field Study ◽  
Water Content ◽  
Pore Water ◽  
Surface Runoff ◽  
Expansive Soil ◽  
Rainfall Infiltration ◽  
Slope Instability ◽  
Simulated Rainfall ◽  
Soil Slope ◽  
Unsaturated Expansive Soil

A full-scale field study was conducted to investigate the effects of rainfall infiltration on a natural grassed expansive soil slope in China. A 16 m wide × 28 m long area was selected for instrumentation. The instrumentation included jet-filled tensiometers, moisture probes, a tipping bucket rain gauge, and a vee-notch flow meter. One artificial rainfall event amounting to about 370 mm rain depth in total was applied to the slope. The monitored results suggested that there was about a 3 day delay in the response of surface runoff, pore-water pressure, and water content to the commencement of the simulated rainfall. The depth of influence of the rainfall, depending on the elevation along the slope, ranged from 2.8 to 3.5 m. Positive pore-water pressures were measured within the influence depth, and there existed significant subsurface downslope flow at the end of the simulated rainfall, particularly near the lower part of the slope. A comparison of infiltration rates between the grassed area and a bare area nearby indicated that the presence of grass significantly increased the infiltration rate and reduced surface runoff. The cracks and fissures developed in the unsaturated expansive soil played an important role in the hydrological process.Key words: expansive soil, slope instability, infiltration, vegetation cover, grass, soil suction, water content, unsaturated soil.

Analyses of Anti-Seepage Measure for Expansive Soil Subgrade in Hefei

2014 ◽  
Vol 580-583 ◽  
pp. 552-555
Author(s):  
Yuan Wei ◽  
Wei Zhong Xing ◽  
Yan Shao
Keyword(s):  
Numerical Calculation ◽  
Moisture Content ◽  
Water Content ◽  
Engineering Design ◽  
Control Measure ◽  
Expansive Soil ◽  
Large Change ◽  
Time Range ◽  
Seepage Control ◽  
Unsaturated Expansive Soil

Deformation of expansive soil subgrade depends on moisture content. Anti-seepage measure of unsaturated expansive soil was carried out using ABAQUS as for the influence of atmosphere. The results show that there is large change in water content using anti-seepage measure measure. After using anti-seepage measure, range of water content decreases. At the same time, range of water content value obviously decreases with the increase of the depth of seepage control. Therefore, damage of pavement caused the deformation can decrease by seepage control measure. The results could be used for engineering design and numerical calculation.

Assessing on the Geotechnical Problems Which Causes for the Road Failure from Gilgel Beles to Bahir Dar Road Segment

2020 ◽  
Vol 11 (10) ◽  
pp. 714-734
Author(s):  
Habtamu Washe Mite ◽  
Maschal Tilahun Zenebe
Keyword(s):  
Expansive Soil ◽  
Organic Soil ◽  
Slope Instability ◽  
Road Segment ◽  
Bahir Dar ◽  
Engineering Structures ◽  
North West ◽  
The North ◽  
Geotechnical Problems ◽  
Road Segments

Geotechnical problems such as problematic soils (expansive soil, organic soil, natural collapsible soils, etc.), problematic rock (shale, weathered limestone), soil slope instability and rock slope instability or rock fall (landslide) which damaged civil engineering structures, such as roads, buildings, dams, railway, and other related structures in Ethiopia. The research was conducted by identifying the geotechnical problems and its effects on road segments in the north west part of Ethiopia, specifically along Gilgel Belles – Bahir Dar road segments. Gilgel Beles – Bahirdar road segment which passes on the hilly and mountainous terrain are characterized by variable topographical, geological, hydrological and land-use condition.

Instrumentation of an Unsaturated Expansive Soil Slope

2007 ◽  
Vol 30 (2) ◽  
pp. 12704 ◽  
Author(s):  
LD Suits ◽  
TC Sheahan ◽  
TLT Zhan ◽  
CWW Ng ◽  
DG Fredlund
Keyword(s):  
Expansive Soil ◽  
Soil Slope ◽  
Unsaturated Expansive Soil

scholarly journals Performance estimation of a shallow foundation on an unsaturated expansive soil slope subjected to rainfall infiltration

2021 ◽  
Vol 337 ◽  
pp. 03009
Author(s):  
Mengxi Tan ◽  
Sai K. Vanapalli
Keyword(s):  
Slope Stability ◽  
Limit Equilibrium ◽  
Expansive Soil ◽  
Rainfall Infiltration ◽  
Performance Estimation ◽  
Shallow Foundation ◽  
Water Infiltration ◽  
Rational Approach ◽  
Soil Slope ◽  
Unsaturated Expansive Soil

In the last two decades, there has been a significant increase in infrastructure development on slopes of hilly regions of the world, due to population growth. There are many infrastructures on unsaturated expansive slopes, especially in semi-arid and arid regions. Rainfall infiltration is one of the major factors that contributes to the slope and infrastructure foundations failures on hilly slopes with unsaturated expansive soils. In the current study, a rational approach is proposed considering the combined influence of the foundation-slope behavior based on the principles of unsaturated soil mechanics. This is achieved by a novel numerical modelling approach using the commercial software Geo-studio to investigate the performance of strip foundation located on the top of the unsaturated expansive soil slope subjected to various rainfall infiltration conditions. Hydro-mechanical coupling analysis is conducted to evaluate the rainfall water infiltration influence combined with slope stability analysis using limit equilibrium method. Comparisons are made between both the foundation bearing capacity, slope stability before and after rainfall water infiltration. Different failure mechanisms of the foundation and slope system are presented with and without foundation loading for various rainfall scenarios. Results summarized in this paper are helpful for the geotechnical engineers for understanding the performance of shallow foundations on unsaturated expansive soil slopes considering the influence of rainfall infiltration conditions.

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