Assessment of suction for local expensive soils

Various types of porous blocks have been used for the indirect measurement of soil suction by various researchers, the usual experience being the importance of appropriate calibration, relatively low accuracy, and slow response. Two types of commercially available porous blocks were used. They were

Project Title

Assessment of suction for local expensive soils

Project Area of Specialization

Cloud Infrastructure

Project Summary

Various types of porous blocks have been used for the indirect measurement of soil suction by various researchers, the usual experience being the importance of appropriate calibration, relatively low accuracy, and slow response. Two types of commercially available porous blocks were used. They were placed in samples undergoing either drying or inundation. Porous blocks were placed always with a tensiometer so that at the range of suctions measured by the tensiometer a comparison could be made between the response of the tensiometer and the porous block. The tests performed involved both slow drying in atmospheric conditions and fast inundation due to wetting. The experience gained from the tests performed is that in the three cases examined and contrary to common experience reported in the , the response of the porous blocks used was comparable to that of conventional tensiometers if not in fact faster

Two types of commercially available, off-the-shelf, porous blocks were used in three different tests (two in the laboratory and one in the field). All sensors used were carefully fully saturated prior to their installation. All the tests also involved relatively coarse-grained soils (coarse sand and even more coarse-grained than that). Both types of sensors responded at least as fast as the tensiometers installed with them for comparison; the MPS-2 yielding values of suction fairly close to those of the tensiometer; the gypsum block not so when using the manufacturer’s universal calibration curve, although was much better when using a sensor-specific calibration curve. 

Project Objectives

The main objective of the project is to assess the effect of the moisture content using different levels of compaction in the SWCC. The curves were obtained using an equipment known as Richard´s pressure chamber (suction chamber): the samples were subjected to upward pressure stages allowing for simulation of a dry process in which the value of the suction matrix increases gradually.  The relationship between optimum compaction moisture content and compaction energy was evaluated in a range between 90 to 100% relative to the maximum dry density. A SWCC model was developed in order to assess with accuracy the local data obtained. 

the main objectives is that we perform basic geotecnical testing on expensive soil and then we use different types of instruments we use just like fredlund apparatus and G block sensor we collected expensive soil  from different area and perform the experiment after that performing that and collecting data from the freedlund apparatus and g blocks sensors and compare both data and noted that how different area of expensive soil behave and we draw soil water carachteristic curve that how the soil sucks when load different load are applied 

Project Implementation Method

 Expansive soils, which are considered as problematic soils, have worldwide distribution and hence, their proper identi?cation and characterisation becomes an absolute necessity in the perspective of the present day geotechnical engineering practice. This project will  intends to gives relative merits of various methods available to a ?eld geotechnical engineer to achieve this important goal.
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Benefits of the Project

Any soil whose volume changes are moisture sensitive is normally considered as an expansive soil. Expansive soils are regarded as problematic soils as they affect the stability of structures founded on them. Hence, it becomes very essential for a practicing geotechnical engineer to appropriately identify and characterise such soils. This in turn will help in material, time, ?nancial and human resource managements, which are the essential components of any project management. 

Technical Details of Final Deliverable

The SWCC is very important in the research of partially saturated soils. However, high variability and numerous sources of error associated to the measured values can lead to difficulties in obtaining a unique SWCC for a given soil.  More tests are needed to grasp the general features of the SWCC, especially to provide information about soil structure, microstructure and macrostructure. However, it is not practical to test samples under every condition. For this reason a minimum series of test for each type of soil should be performed to establish the effects and influence of different factors on the SWCC of the soil.  It was shown that the initial density has a significant impact on the SWCC due to the reduction of the amount of voids in the soil, therefore a decrease on the amount of voids allows a gain on the degree of saturation (S). Additionally, the saturated water content (?s) increases due to the density and the residual volumetric water content (????????) has little variation at high suctions values (higher than 1000 kPa) for all the evaluated densities.  An adequate model for the SWCC is essential to further perform constitutive modeling. In this regard, an updated model is proposed to predict the SWCC curve for a Costa Rican soil. Comparisons between measured and modeled SWCCs proved the model's capability and accuracy. Further studies are required to analyze the relationship between the SWCC and other geotechnical and soil parameters such as void ratio, initial water content, stress state, grain size, and plasticity among other variables.

Final Deliverable of the Project

HW/SW integrated system

Core Industry

Transportation

Other Industries

Education , Manufacturing

Core Technology

Augmented & Virtual Reality

Other Technologies

Others

Sustainable Development Goals

Industry, Innovation and Infrastructure

Required Resources

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