Engineering properties of unsaturated soils (volume change and permeability)

2020 ◽  
pp. 353-356
Author(s):  
K. Premalatha
Keyword(s):  
Volume Change ◽  
Unsaturated Soils ◽  
Engineering Properties

A novel non-contacting laser displacement transducer technique for volume change measurements of unsaturated soils

2010 ◽  
pp. 751-756 ◽  
Author(s):  
X Zhang ◽  
M Mavroulidou ◽  
M Gunn ◽  
Z Cabarkapa ◽  
J Sutton
Keyword(s):  
Volume Change ◽  
Unsaturated Soils ◽  
Displacement Transducer

Soil-water characteristic curve and consolidation behavior for a compacted silt

2007 ◽  
Vol 44 (3) ◽  
pp. 266-275 ◽  
Author(s):  
Trinh Minh Thu ◽  
Harianto Rahardjo ◽  
Eng-Choon Leong
Keyword(s):  
Soil Water ◽  
Volume Change ◽  
Unsaturated Soils ◽  
Water Pressure ◽  
Characteristic Curve ◽  
Matric Suction ◽  
Confining Stress ◽  
Soil Water Characteristic Curve ◽  
Triaxial Cell ◽  
Isotropic Consolidation

Measurement of the soil-water characteristic curve (SWCC) in the laboratory is commonly conducted under zero confining pressure. However, in the field, the soil is under a confining stress. Therefore, it is important to study the effects of the confining stress on SWCC. In addition, the consolidation curve is normally generated under saturated conditions. However, the soil above the water table is usually unsaturated. Hence, it is also necessary to investigate the effects of matric suction on the characteristics of the consolidation curves. This paper presents the SWCCs under different net confining stresses and the isotropic consolidation curves under different matric suctions that describe the volume change characteristics of unsaturated soils with respect to stress state variables, net normal stress, and matric suction. A series of SWCCs was determined for statically compacted silt specimens in a triaxial cell apparatus under different net confining stresses. Isotropic consolidation tests under different matric suctions were also carried out. The results of the SWCC tests show that the air-entry value increased with increasing net confining stress. The yield points (i.e., yield suction, s0) obtained from the SWCC tests also increased with increasing net confining stress. The results of isotropic consolidation tests indicate the strong influence of matric suction on compressibility and stiffness of the compacted silt specimens.Key words: soil-water characteristic curve, isotropic consolidation, pore-water pressure, volume change, NTU mini suction probe, matric suction.

A Diffused Air Volume Indicator for Unsaturated Soils

1975 ◽  
Vol 12 (4) ◽  
pp. 533-539 ◽  
Author(s):  
D. G. Fredlund
Keyword(s):  
Correction Factor ◽  
Volume Change ◽  
Unsaturated Soils ◽  
Effective Means ◽  
Computational Procedure ◽  
Technical Note ◽  
Water Volume ◽  
Volume Weight ◽  
Air Volume ◽  
Change Characteristics

The diffusion of air through saturated high air entry discs presents a serious problem in the testing of unsaturated soils. When determining either the strength (drained) or volume change characteristics of unsaturated soils, a technique must be available to measure the amount of diffused air in order for the appropriate corrections to be applied to the volume–weight relationships.The described diffused air volume indicator is a simple but effective means of measuring the quantity of diffused air. This technical note explains its construction and procedure of operation. Also outlined is the computational procedure for the correction factor that must be applied to the water volume change measurements. Numerous tests on the indicator show a reliability in the order of ±0.2 cc over a period of 2.5 weeks.

A new simple system for measuring volume changes in unsaturated soils

2002 ◽  
Vol 39 (3) ◽  
pp. 757-764 ◽  
Author(s):  
C W.W Ng ◽  
L T Zhan ◽  
Y J Cui
Keyword(s):  
Volume Change ◽  
Unsaturated Soils ◽  
Volumetric Strain ◽  
Apparent Volume ◽  
Differential Pressure ◽  
Simple System ◽  
Measuring System ◽  
Volume Changes ◽  
Ambient Temperatures ◽  
Triaxial Apparatus

A new simple system for accurately measuring overall total volume changes in unsaturated soil specimens with a triaxial apparatus is introduced in this paper. The basic principle of the measuring system is to record changes in the differential pressure due to changes in the water level inside an open-ended, bottle-shaped inner cell caused by volume change in the specimen and inside a reference tube using an accurate differential pressure transducer. Several important steps were taken to improve the accuracy and sensitivity of the measuring system. Detailed calibrations were carried out to account for apparent volume changes as a result of changes in cell pressure, fluctuation in the ambient temperatures, creep in the inner cell wall, and relative movement between the loading ram and the inner cell. The calibration results demonstrate that the measuring system is reasonably linear, reversible, and repeatable. The estimated accuracy of the measuring system is in the order of 32 mm3 (or 0.04% volumetric strain for a triaxial specimen 38 mm in diameter and 76 mm in height) once the system is properly calibrated.Key words: unsaturated soils, volume-change measurement, open-ended, bottle-shaped, inner cell, differential pressure, calibration.

Settlement rate of foundations on unsaturated soils

1999 ◽  
Vol 36 (5) ◽  
pp. 940-946 ◽  
Author(s):  
Ernesto Ausilio ◽  
Enrico Conte
Keyword(s):  
Volume Change ◽  
Unsaturated Soil ◽  
Unsaturated Soils ◽  
Shallow Foundations ◽  
Settlement Rate ◽  
One Dimensional ◽  
Consolidation Rate ◽  
Degree Of Consolidation ◽  
The One ◽  
External Loads

This paper deals with the one-dimensional consolidation of unsaturated soils due to the application of external loads. A simple equation is derived that enables one to predict the rate of settlement of shallow foundations with time. This equation uses the constitutive relationships proposed by Fredlund and Morgenstern to define the volume change of unsaturated soils, and relates the settlement rate to the average degree of consolidation for both the water and air phases. A series of examples is shown to demonstrate the feasibility and usefulness of the derived equation. Key words: one-dimensional consolidation, unsaturated soil, degree of consolidation, rate of settlement.

scholarly journals Effect of Saturation Levels on Shear Strength and Bearing Capacity Properties of Soil Types

2019 ◽  
Vol 54 (6) ◽  
Author(s):  
Mahmood D. Ahmed ◽  
Alaa D. Almurshedi ◽  
Hayder H. Alwan
Keyword(s):  
Bearing Capacity ◽  
Unsaturated Soils ◽  
Soil Classification ◽  
Soil Samples ◽  
Engineering Properties ◽  
Test Results ◽  
Soil Layers ◽  
Angle Of Internal Friction ◽  
Noticeable Reduction ◽  
Properties Of Soil

This study presents a comprehensive set of laboratory works for the examined soil layers extracted from Baghdad city (specifically from Alkadhimya, Alaitaifiya, and Alhurriya) to illustrate their engineering properties. The researchers have adopted the unified soil classification system for soil classification purposes. Also, the direct shear test was performed for soil samples with various degrees of saturation (0%, 25%, 50%, 75%, and 100%). The test results have shown a significant reduction in cohesion property with higher moisture content within soil samples. Also, a noticeable reduction in angle of internal friction value has occurred with such changes. Furthermore, it has been found that the bearing capacity of unsaturated soils ranged between 2000 and 3000 KPa, and about 500-700 KPa for the soaked soil samples.

Sign in / Sign up

Export Citation Format

Share Document