Analysis of Rainfall-induced Landslide Using the Extended DDA by Incorporating Matric Suction

2021 ◽  
Vol 135 ◽  
pp. 104145
Author(s):  
Longxiao Guo ◽  
Guangqi Chen ◽  
Shilin Gong ◽  
Hao Sun ◽  
Krisadawat Chantat
Keyword(s):  
Matric Suction

scholarly journals The Influence of Drying-Wetting Cycles on the Suction Stress of Compacted Loess and the Associated Microscopic Mechanism

Water ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 1809
Author(s):  
Yongpeng Nie ◽  
Wankui Ni ◽  
Xiangning Li ◽  
Haiman Wang ◽  
Kangze Yuan ◽  
...  
Keyword(s):  
Filter Paper ◽  
Pore Diameter ◽  
Matric Suction ◽  
Microscopic Mechanism ◽  
Suction Stress ◽  
Dominant Soil ◽  
Before And After ◽  
Soil Pores ◽  
Paper Method ◽  
Compacted Loess

To better understand and analyze the unsaturated stability of loess filling body, it is necessary to study the changes in suction stress before and after the drying-wetting cycles. In this study, the SWCC of compacted loess before and after drying-wetting cycles was tested using the filter paper method. Then, the suction stress was calculated and the microstructure of the loess sample was determined by the SEM and NMR. The results showed that the drying-wetting cycles had an important influence on the SSCC and microstructure of compacted loess. The change in suction stress before and after the drying-wetting cycles can be well explained by the loess microstructure. The drying-wetting cycles did not significantly change the basic trend of the compacted loess’s SSCC, but it increased the porosity and the dominant pore diameter of loess, and reduced the suction stress under the same matric suction. The main significant change in suction stress with matric suction occurred within the range of the dominant soil pores. The larger the dominant pore diameter, the smaller the suction stress under the same matric suction. In addition, this study proposes a new method for calculating suction stress based on the PSD parameters.

EFFECT TO TEMPERATURE AND TRAPPED AIR ON MATRIC SUCTION

Soil Science ◽  
1965 ◽  
Vol 100 (4) ◽  
pp. 262-266 ◽  
Author(s):  
R. S. CHAHAL
Keyword(s):  
Matric Suction ◽  
Trapped Air

Bearing Capacity Characteristic of Unsaturated Granular Soils

2011 ◽  
Vol 261-263 ◽  
pp. 989-993 ◽  
Author(s):  
Anuchit Uchaipichat ◽  
Ekachai Man Koksung
Keyword(s):  
Bearing Capacity ◽  
Matric Suction ◽  
Ultimate Bearing Capacity ◽  
Experimental Program ◽  
Granular Soils ◽  
Test Results ◽  
High Level ◽  
Unsaturated Granular Soils ◽  
Capacity Characteristic

An experimental program of laboratory bearing tests was performed to characterize the bearing capacity of foundation on unsaturated granular soils. All tests were performed by pushing a circular rod on the surface of compacted sand specimens with different values of matric suction until failure. The test results show an increase in ultimate bearing capacity with increasing matric suction at low suction value but a decrease in that at high level of suction. The comparisons between the test results and simulations using the expressions proposed in this paper are presented and discussed. Good agreements are achieved for all testing values of suction.

Shear strength and dilative characteristics of an unsaturated compacted completely decomposed granite soil

2010 ◽  
Vol 47 (10) ◽  
pp. 1112-1126 ◽  
Author(s):  
Md. Akhtar Hossain ◽  
Jian-Hua Yin
Keyword(s):  
Shear Strength ◽  
Normal Stress ◽  
Matric Suction ◽  
Water Retention Curve ◽  
Direct Shear ◽  
Normal Stresses ◽  
Soil Water Retention Curve ◽  
Strength Data ◽  
Decomposed Granite ◽  
Completely Decomposed Granite

Shear strength and dilative characteristics of a re-compacted completely decomposed granite (CDG) soil are studied by performing a series of single-stage consolidated drained direct shear tests under different matric suctions and net normal stresses. The axis-translation technique is applied to control the pore-water and pore-air pressures. A soil-water retention curve (SWRC) is obtained for the CDG soil from the equilibrium water content corresponding to each applied matric suction value for zero net normal stress using a modified direct shear apparatus. Shear strength increases with matric suction and net normal stress, and the failure envelope is observed to be linear. The apparent angle of internal friction and cohesion intercept increase with matric suction. A greater dilation angle is found at higher suctions with lower net normal stresses, while lower or zero dilation angles are observed under higher net normal stresses with lower suctions, also at a saturated condition. Experimental shear strength data are compared with the analytical shear strength results obtained from a previously modified model considering the SWRC, effective shear strength parameters, and analytical dilation angles. The experimental shear strength data are slightly higher than the analytical results under higher net normal stresses in a higher suction range.

LABORATORY FOOTING TEST ON PARTIALLY SATURATED SANDY SOIL

2016 ◽  
Vol 78 (5-5) ◽  
Author(s):  
J. D. Nyuin ◽  
M. J. Md Noor ◽  
Y. Ashaari ◽  
C. Petrus ◽  
A. Albar
Keyword(s):  
Sandy Soil ◽  
Ground Surface ◽  
Matric Suction ◽  
Shallow Foundation ◽  
Analysis And Design ◽  
Test Tank ◽  
Partially Saturated ◽  
Saturated Condition ◽  
Conventional Analysis ◽  
The Relationship

Conventional analysis and design of shallow foundation are based on the assumption that the soil is under fully saturated condition. However, shallow foundations are typically constructed near the ground surface where the soil is under partially saturated condition. Therefore, more research to investigate the behaviour of shallow foundation in unsaturated soil is very essential in order to aid engineers in making good analysis and design. This paper presents a series of laboratory footing tests conducted on unsaturated sandy soil. A specially designed test tank was fabricated for the test. Square footings of two different sizes (100 mm x 100 mm and 150 mm x150 mm) were used and loaded on Rawang sand which has residual suction value of 10 kPa. The measured values of matric suction of the soil in the test tank were in the range of 0 to 30 kPa. Based on the results, it was observed that bearing capacities of shallow foundation under fully saturated condition were the lowest compared to soil under unsaturated conditions. The highest values were measured at matric suction equals to residual suction (i.e 10 kPa). Furthermore, the relationship between the bearing capacities of shallow foundation with the matric suction was observed to be non-linear.    

ANALYSIS OF SUCTION DISTRIBUTION RESPONSE TO RAINFALL EVENT AND TREE CANOPY

2016 ◽  
Vol 78 (8-5) ◽  
Author(s):  
Mohd FakhrurazziIshak ◽  
Nazri Ali ◽  
Azman Kassim
Keyword(s):  
Matric Suction ◽  
Field Monitoring ◽  
Rainfall Event ◽  
Tree Canopy ◽  
Dominant Factor ◽  
Residual Soil ◽  
Initial Condition ◽  
Canopy Interception ◽  
Rainfall Events ◽  
Sloping Surface

This study provides an exploration of matric suction influenced by tree canopy interception on a single rainfall event. A field monitoring was carried out to measure matric suction at slope with two conditions; at toe of slope without tree and with a tree at toe of slope on a tropical residual soil. The variation in matric suction values and matric suction profiles response to the rainfall events on slope with and without a tree at toe were analysed to reveal the effect of the tree canopy. At initial condition, the matric suction was significantly higher at vicinity of tree compared to that of area without tree at toe of slope. However, a typical short and intense tropical rainfall has caused the matric suction to drop dramatically to a minimum value on slope without tree. This condition did not occur on slope with tree. Although, both slopes (with and without tree at toe) received the same amount of precipitation rainfall but the different responses in matric suction valueswere clearly shown at slope with tree at the slope toe. The short and intense rainfalls appeared to be the dominant factor to the suction variation at slope without tree, but not at slope with the tree. The tree canopy can be a factor to influence the suction variation at slope with tree as canopy interception reduced the amount of precipitation to the ground/sloping surface

Pile Capacity in Homogeneous Unsaturated Sand Layer

2011 ◽  
Vol 110-116 ◽  
pp. 13-17
Author(s):  
Anuchit Uchaipichat ◽  
Ekachai Man Koksung
Keyword(s):  
Pile Foundation ◽  
Factor Of Safety ◽  
Matric Suction ◽  
Earth Surface ◽  
Sand Layer ◽  
Pile Capacity ◽  
Natural Soils ◽  
Unsaturated Sand ◽  
The Earth ◽  
Dry Conditions

Generally, pile foundation is typically chosen to support heavy structures. However, the developments of expressions to determine the pile capacity is usually based on fully saturated and completely dry conditions. In fact, almost 40 percent of natural soils on the earth surface are in an unsaturated state. Thus, in this paper, an expression for pile capacity in homogeneous unsaturated sand layer is developed. The simulations using developed expression are performed and discussed. Typical results show that the pile capacity and the factor of safety are affected by matric suction. However, the influence of matric suction may be ignored for a long pile.

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