Investigation of the geotechnical properties and estimation of the relative density from the standard penetration test in sandy soils (Case study: north east of Iran)

In the present research, SPT results are adopted to establish relationships for estimation of the relative density in a sandy soil. SPTs are performed in 20 boreholes in Astaneh-ye Ashrafiyeh city in Iran. Laboratory tests including mineralogy, relative density, soil gradation, Atterberg limits, and unit weight were performed on the soil samples. The SPT numbers were then properly corrected. In particular, the correct procedure for correction of the SPT number against the existing overburden effective stress is discussed when the SPT is performed in the vadose zone where the soil may be unsaturated. The soil in the study area is dominantly classified as SP-SM. The relationship between the relative density as one of the most important parameters for dominantly granular soils, with the corrected SPT number (N 1(60) ) and fines content is then investigated and discussed using artificial neural network and statistical analysis. Results showed that for the soil of interest, the developed relationship performs better than those established in the literature, hence demonstrating the value of developing locally tuned relationships for important projects.

Utilizing Hyperspectral Remote Sensing for Soil Gradation

Soil gradation is an important characteristic for soil mechanics. Traditionally soil gradation is performed by sieve analysis using a sample from the field. In this research, we are interested in the application of hyperspectral remote sensing to characterize soil gradation. The specific objective of this work is to explore the application of hyperspectral remote sensing to be used as an alternative to traditional soil gradation estimation. The advantage of such an approach is that it would provide the soil gradation without having to obtain a field sample. This work will examine five different soil types from the Keweenaw Research Center within a laboratory-controlled environment for testing. Our study demonstrates a correlation between hyperspectral data, the percent gravel and sand composition of the soil. Using this correlation, one can predict the percent gravel and sand within a soil and, in turn, calculate the remaining percent of fine particles. This information can be vital to help identify the soil type, soil strength, permeability/hydraulic conductivity, and other properties that are correlated to the gradation of the soil.

Perbaikan Subgrade pada Jalan Kampung Keramat di Kota Pangkalpinang dengan Menggunakan Kapur Padam Sebagai Bahan Stabilisasi Tanah

Soil is the main support in a construction. Unstable soil conditions, especially in the subgrade can cause damage to the road. Based on the results of a direct survey in the field, it was found that the condition of the Jalan Kampung Keramat in Pangkalpinang City was damaged. This might be caused by the condition of the subgrade on the road which is unstable and the subgrade is categorised as clay soil type. This study aims to improve the subgrade on Jalan Kampung Keramat in Pangkalpinang City by using limestone as a soil stabilization material. This study used an experimental method in the laboratory by making mixture between clay soil and limestone with four different variations in the percentage of limestone, namely 0%, 3%, 5%, 7%. There are four parameters of the mixed characteristics that are tested and analysed, namely: the Atterberg limit, specific gravity, soil gradation and CBR value. The results show that the Atterberg limit values ​​(liquid limit-LL and plasticity index-IP) and specific gravity tend to decrease with increasing percentage of limestone extinguished. However, the plastic limit value (PL) shows the opposite tendency, i.e. it increases with the decreasing percentage of limestone. The specific gravity values ​​obtained based on the percentage of lime outages (0%, 3%, 5%, 7%) are 2.63, 2.61, 2.60, and 2.58, respectively. In addition, the addition of limestone causes changes in soil gradation, namely the addition of retained fraction # No.200 and the reduction of passed fraction # No.200. The Addition of limestone can increase the CBR value of the soil, where the addition of 7% of limestone produces the highest CBR value (21.3%) compared to 5% limestone (15.7%), 3% limestone (13.4%) and 0% limestone (11.2%). Therefore, using limestone can improve quality of subgrade, which can be seen from the value of CBR obtained.

Effect of Coarse Aggregate Columns on Angle of Friction in Fine Sandy Soil

the study adopted samples from Tigris river shoulders ,which has been subjected to such collapses and cracks. After testing and investigation it was found the soil is formed from river deposits , which can be classified as fine sand soil . It is known that many of the collapses that occurs in the sides of rivers are due to the influence of shear forces . A different of diameters coarse aggregates columns and aggregates sizes used in this study are tested by direct shear test. The main objective of this research to increase the coefficient of friction between the soil particles in the test specimen by adding the coarse aggregate columns to the fine sand soil, In this regard the least void ratio was found as a beneficial index that relates with critical state of friction angle independent on soil gradation. The relations between critical state or high friction angles of the mixture with lower void ratio were determined as a function of addition pressure. The relationships could be useful to determination the strength parameters of (sand gravel mixtures).

Monitoring Leachate Migration in Compacted Soil Using Digital Image Technique

As leachate has been a source of groundwater contamination worldwide, this paper examines the phenomenon of leachate migration on different gradations of compacted laterite soil used as sanitary landfill liners. Three different soil gradations (30%, 40% and 50% with respect to fines content) used in this study were compacted in circular acrylic columns to provide a clear visualization of leachate migration into the soils. Digital image technique was used in capturing photos at successive time intervals to monitor the leachate migration. The captured digital images were fed into Matlab and converted into hue-saturation-intensity (HSI) format. Surfer software then read the HSI and generated 2D contour plots. The results of the experiments showed that the leachate moves downward faster in the soil gradation with the least fines content. Hydraulic conductivity values decrease with increase in time duration and equally with increase in fines content. The hydraulic conductivities of the leachate for 30%, 40% and 50% fines were 3.64×10-9m/s, 2.40×10-9m/s, and 1.24×10-9m/s respectively. This reveals that for tropical laterite soils, gradation containing 50% fines content provides better hydraulic conductivity. The use of noninvasive digital image technique can enable designers/engineers to monitor and visualize the leachate migration in compacted soils in waste containment application systems.