Boreholes

Radiation originates from anthropogenic, primordial, and cosmogenic sources.
The impact of radiation through anthropogenic and cosmogenic sources is negligible
to the environment while the primordial radioactivity is widely distributed in the earth
and its environs. This radioactive material and its Byproducts are found mainly in
diverse geological formations around us. Inadequate access to public water supply in
Abuja has forced more than 80 percent of the population of about 5 million to drill
private boreholes. Nigerian drillers are unaware of high concentrations of
radioactivity present in granitic rocks which vary with depth. The radioactivity of
226Ra as well as 232Th decay chains for the lithological rock samples could be at
equilibrium considering the age as well as the isotopic mass proportion which is
assumed to be equal to its natural isotope. Neutron Activation Analysis (NAA) is
adopted for this study with the aim of minimizing sample size as well as less counting
rate in order to estimate the radioactivity concentration in rock samples. Two
boreholes are drilled in Abuja in order to randomly collect the rock samples from
three different layers of each site. All the samples were duplicated for each
radionuclide examination, resulting to twelve samples in all. The results showed that
the activity concentrations of 226Ra, 232Th and 40K in the two sites were in the order
232Th > 226Ra > 40K. 226Ra and 232Th possess activity concentration greater

Radiation originates from anthropogenic, primordial, and cosmogenic sources.
The impact of radiation through anthropogenic and cosmogenic sources is negligible
to the environment while the primordial radioactivity is widely distributed in the earth
and its environs. This radioactive material and its Byproducts are found mainly in
diverse geological formations around us. Inadequate access to public water supply in
Abuja has forced more than 80 percent of the population of about 5 million to drill
private boreholes. Nigerian drillers are unaware of high concentrations of
radioactivity present in granitic rocks which vary with depth. The radioactivity of
226Ra as well as 232Th decay chains for the lithological rock samples could be at
equilibrium considering the age as well as the isotopic mass proportion which is
assumed to be equal to its natural isotope. Neutron Activation Analysis (NAA) is
adopted for this study with the aim of minimizing sample size as well as less counting
rate in order to estimate the radioactivity concentration in rock samples. Two
boreholes are drilled in Abuja in order to randomly collect the rock samples from
three different layers of each site. All the samples were duplicated for each
radionuclide examination, resulting to twelve samples in all. The results showed that
the activity concentrations of 226Ra, 232Th and 40K in the two sites were in the order
232Th > 226Ra > 40K. 226Ra and 232Th possess activity concentration greater

This project was aimed at evaluating and developing design methods for laterally loaded drilled shafts socketed in rock. Five lateral load tests on rock socketed drilled shafts with full range of instrumentation were conducted in Ohio. Detailed instrumentation included the use of vibrating wire strain gages, inclinometers, dial gages, and load cells. P-y curves representing site-specific lateral shaft-rock interaction were deduced from strain data. Field testing included the use of a borehole pressuremeter/dilatometer to obtain measurements that were correlated with rock mass strength and deformation parameters as well as with p-y curves. A comparison was made between the baseline p-y curves deduced from strain data of lateral load tests, the p-y curves predicted by using Reese’s interim criterion, and the p-y curves from the pressuremeter tests in rock. A new hyperbolic p-y criterion for rock is proposed based on the field test data and extensive theoretical work. Validation of the...

This paper describes the implementation and successful validation of a new staggered-grid, finite-difference algorithm for the numerical simulation of frequency-domain electromagnetic borehole measurements. The algorithm is based on a coupled scalar-vector potential formulation for arbitrary 3D inhomogeneous electrically anisotropic media. We approximate the second-order partial differential equations for the coupled scalar-vector potentials with central finite differences on both Yee’s staggered and standard grids. The discretization of the partial differential equations and the enforcement of the appropriate boundary conditions yields a complex linear system of equations that we solve iteratively using the biconjugate gradient method with preconditioning. The accuracy and efficiency of the algorithm is assessed with examples of multicomponent-borehole electromagnetic-induction measurements acquired in homogeneous, 1D anisotropic, 2D isotropic, and 3D anisotropic rock formations. T...

The cone penetration test (CPT) has been widely used in Louisiana in the last two decades as an in situ tool to characterize engineering properties of soils. In addition, conventional drilling and sample retrieval using Shelby tube followed by laboratory testing is still the acceptable practice in identifying soils engineering properties. The main objective of this project is to update the correlations that are currently used by Louisiana Department of Transportation and Development (LADOTD) to interpret CPT data for engineering design purposes and to assess the reliability of using CPT data to predict soil shear strength in both the magnitude and spatial variations in the field with respect to the Load and Resistance Factor Design (LRFD) methodology. The results of laboratory soil testing were retrieved from borehole logs and were used as reference measurements in this study. The research team collected project data files in paper printout format from LADOTD and soil testing engine...