Local soil conditions influence the characteristics of earthquake ground shaking and these effects must be taken into account when specifying ground shaking levels for seismic design. These effects are quantified via site response analysis, which involves the propagation of earthquake motions from the base rock through the overlying soil layers to the ground surface. Site response analysis provides surface acceleration-time series, surface acceleration response spectra, and/or spectral amplification factors based on the dynamic response of the local soil conditions. This dissertation investigates and compares the results from different site response methods. Specifically, equivalent-linear time series analysis, equivalent-linear random vibration theory analysis, and nonlinear time series analysis are considered. In the first portion of this study, hypothetical sites and events are used to compare the various site response methods. The use of hypothetical events at hypothetical sites allowed for the seismic evaluation process used in engineering practice to be mimicked. The hypothetical sites were modeled after sites with characteristics that are representative of sites in the Eastern and Western United States. The input motions selected to represent the hypothetical events were developed using the following methods: stochastically-simulated time series, linearly-scaled recorded time series, and spectrally-matched time series. The random vibration theory input motions were defined using: seismological source theory, averaging of the Fourier amplitude spectra computed from scaled time series, and a response spectrum compatible motion. All of the different input motions were then scaled to varying intensity levels and propagated through the sites to evaluate the relative differences between the methods and explain the differences. Data recorded from borehole arrays, which consist of instrumentation at surface and at depth within the soil deposit, are used to evaluate the absolute bias of the site response methods in the second portion of this study. Borehole array data is extremely useful as it captures both the input motion and the surface motion, and can be used to study solely the wave propagation process within the soil deposit. However, comparisons using the borehole data are complicated by the assumed wavefield at the base of the array. In this study, sites are selected based on site conditions and the availability of high intensity input motions. The site characteristics are then developed based on site specific information and data from laboratory soil testing. Comparisons between the observed and computed response are used to first assess the wavefield at the base of the array, and then to evaluate the accuracy of the site response methods. / text

Žemės šilumos siurblių sistemos surenka žemės šilumą, dažniausiai vertikaliu U formos gręžinio šilumokaičiu. U formos gręžinio šilumokaičio našumas priklauso nuo šiluminių žemės savybių, taip pat nuo gręžinyje naudojamo skiedinio ar užpildo. Siekiant, kad Žemės šilumos siurblių sistemos pasiteisintų, projektuojant reikia atsižvelgti į geologinių struktūrų šiluminį laidumą ir gręžinio šilumokaičio šiluminę varžą. Šio darbo tikslas buvo nustatyti šilumos siurblio, naudojančio grunto šilumą, pritaikymo individualioje sodyboje siurblio techninis ir ekonominis įvertinimas. Nustatyta, kad investicijos projektui įgyvendinti, kai gyvenamajam pastatui šildyti ir buitiniam karštam vandeniui ruošti šildymo sezono metu šilumą gamina šilumos siurblys, naudojantis grunto šilumą, palyginti su tiesioginiu elektros naudojimu pastatui šildyti ir buitiniam karštam vandeniui ruošti, atsiperka per 6,3 metus. Šiluminės reakcijos testas padeda nustatyti šiluminį žemės laidumą (λ) gręžinio šilumokaičio įrengimo vietoje, bei efektyvią gręžinio šilumokaičio šiluminę varžą (Rb). Pagrindinis tikslas buvo suderinti gręžinio šilumokaitį su žemės sąlygomis, taip pat nustatyti gręžinio gylio poveikį (60 m: VB2; 90 m: VB3). / Ground source heat pump systems exchange heat with the ground, often through a vertical, U-tube, borehole heat exchanger. The performance of this U-tube borehole heat exchanger depends on the thermal properties of the ground formation, as well as grout or backfill in the borehole. The design and economic probability of ground source heat pump systems need the thermal conductivity of geological structure and thermal resistance of borehole heat exchanger. An economic and technical evaluation of the heat pump, which is using ground heat, in individual homestead. It was found that the investment for this project, when heat pump using ground heat is used to heat residential building and domestic hot water in heating season, compared with the use of direct electric heating of buildings and domestic hot water payback within 6.3 years. Thermal response test method allows the in-situ determination of the thermal conductivity (l) of the ground formation in the vicinity of a borehole heat exchanger, as well as the effective thermal resistance (Rb) of this latter. The main goal has been to determine same in-situ ground type of borehole heat exchanger, including the effect of borehole’s depths (60 m: VB2; 90 m: VB3).

No description available.

The objective of this study was to examine three well designs: drilled wells (20-30 m deep), closed dug wells (>5 m deep), and hand-dug open wells (<5 m deep), to determine the water quality for improving access to safe and clean water in rural communities. Heterotrophic plate count (HPC), total coliforms (TC), Escherichia coli (E. coli) and turbidity, were used to assess the water quality of 97 wells. Additionally, the study looked at the microflora diversity of the water, focusing on potential pathogens using outgrowth, PCR, and genome sequencing for 10 wells. Concentrations of TC for the open dug wells (4 x 10(4) CFU/100 mL) were higher than the drilled (2 x 10(3) CFU/100 mL) and closed dug wells (3 x 10(3) CFU/100 mL). E. coli concentration for drilled and closed dug wells was <22 MPN (most probable number)/100 mL, but higher for open wells (>154 MPN/100 mL). The drilled well turbidity (11 NTU) was within the standard deviation of the closed well (28 NTU) compared to open dug wells (49 NTU). Drilled and closed wells had similar microbial diversity. There were no significant differences between drilled and closed dug wells. The covering and lining of hand-dug wells should be considered as an alternative to improve access to safe and clean water in rural communities.

The Ground Source Heat Pump systems (GSHP) are an emerging technology used to exchange heat with the ground through the use of some buried heat exchangers. The thermal response of a borehole field can be characterized by its g-function. It is a non-dimensional temperature response factor, which can be calculated using either numerical or analytical solutions. Eskilson developed the first study made for the calculation of these g-functionts. Lamarche and Beauchamp proposed another analytical approach based on the Finite Line Source (FLS). Generally, both solutions present similar results with some small differences. They could be attributed to the boundary condition performed in both researches: the FLS solution considers uniform heat flux along the borehole wall in all the heat exchangers, while Eskilson’s model defines as a condition, uniform temperature at the borehole wall within all the pipes in the field. In this Master of Science Thesis, the temperature response factors (g-functions) of a 6x6 borehole field with 36 heat exchangers (BHE) arranged in a squared configuration are obtained from new numerical models, mainly based on the use of a highly conductive material composing the BHE. For this purpose, a commercial software called Comsol Multyphisics© is employed. The aim of this thesis is to get larger knowledge in generating the g-function in relation to the boundary condition performed in the model trying to reach better approximations to the reality. Some strategies with respect to the geometry, size of the model and mesh are performed to reduce the computing time. The influence of the geothermal heat flux and the influence of the highly conductive material (HCM) composing the BHEs are also studied in our model. Going further, the thermal behavior of the ground is also studied by imposing variable heating and cooling loads during seasonal periods over a time of 25 years. Finally, the g-functions obtained from our numerical models are compared to the one generated with the commercial software, Earth Energy Design (EED), which represents the numerical solution proposed by Eskilson, and the one generated with FLS approach. The results may explain in a closer approximation to the reality the thermal response for large borehole fields.

Nowadays Ground Source Heat Pumps (GSHP) are widely used to provide heating and/or cooling as well as domestic hot water in commercial and residential buildings. The Swedish GSHPs market is the first one in the European Union with more than 378,000 units installed until 2010 according to the Swedish Heat Pump Association (SVEP). This thesis focuses on the improvement of a Thermal Response Test (TRT) apparatus available at KTH Royal Institute of Technology – Energy Technology Department. This equipment aims at improving Borehole Heat Exchanger (BHE) design in terms of size. Its key purpose is to evaluate two main BHE properties: the ground thermal conductivity and the borehole thermal resistance. A new command software is developed in order to control the TRT equipment and run TRT measurements. This new software is developed using Python as programming language and replaces an older program which needed LabVIEW to run. The TRT command software designed in this thesis provides the user with a simple and user-friendly interface to control each device of the equipment. Measurements are exported and saved to files which can be open with both Microsoft Excel and the analysis tool also developed in this thesis. The stand-alone evaluation tool can be used to analyse TRT and/or DTRT measurements. This analysis tool helps the user to compute large amount of data with few data manipulation and low computation time. Model parameters and TRT/DTRT measurement can be imported from files into it and different fitting settings are available to run the optimization, i.e. account for baseline variations (early activities in the borehole, different optimization periods, analysis during thermal recovery of the ground, single/multi-sectional analysis along the depth, among others). This report covers a theoretical description of TRT experiments and its models, the objectives of such a project and the development of the control and evaluation tools.

This thesis analyzes the potential systematic errorin the characterization of the rock mass quality in borehole and tunnel mapping. The difference when assessing the rock mass quality refers to the fact that the characterization performed on drilled rock cores are commonly done on-meter length, while the tunnel section can be up to 20-25 m wide. At the same time, previous studies indicate that the engineering geologist tends to characterize the rock mass quality during tunnel excavation with a conservative estimation of the parameters defining the rock mass quality to ensure a sufficient rock support. In order to estimate this possible systematic error produced by the size difference when assessing the rock mass quality, a simulation was performed within a geological domain, representative of Stockholm city. In the simulation, each meter of the tunnel section was given a separate value of the rock mass quality, randomly chosen from a normal distribution representative for the studied geological domain. The minimum value was set to represent the characterized rock mass quality for that tunnel section. The results from the simulation produced a systematic error due to the difference between the geological domain, reproducing the borehole mapping, and the simulated values, representing the tunnel mapping. The results showed a systematic error in the RMR basic index around 15 points in average, which compared to the difference of 5-7 points obtained in Norrström and the Norrmalm tunnels in the Stockholm Citylink project recently constructed, are found to be excessive. However, in the simulation, it was assumed that (1) the results obtained were the same in the bore hole mapping and in the tunnel mapping, (2) with the only difference of the engineer geologist assigning to the tunnel section the lowest RMR basic value, and (3) that there was no spatial correlation between the quality RMR basic index. After analyzing the three assumptions the simulation was based upon, the absence of spatial correlation was found to be the most significative, which indicate that spatial correlation in rock mass quality needs to be included if a more correct value should be obtained.

A ground source heat pump (GSHP) system utilizes a borehole heat exchanger to extract energy from the ground during the heating season and to deposit energy during the cooling season. This requires the drilling of an extended borehole, typically ranging from 100 to 200 meters in length, with a diameter of approximately 6 to 8 inches. Inside the borehole, a U-shaped tube is placed and surrounded by a grout that aids heat transfer between the tube and the surrounding soil. A heat transfer fluid, often a mixture of water and glycol, circulates through the tube to exchange heat with the ground. During the winter, the system draws energy from the ground for household space heating, while in the summer, when air conditioning is used, it expels energy from the house into the ground. In regions with heating-dominated climates, such as Canada, more energy is withdrawn from the ground during the winter than can be naturally restored during the summer. Consequently, the soil progressively cools over time, leading to reduced heat pump coefficient of performance and a decline in the overall system efficiency. This study explores a solution to this issue by integrating solar domestic hot water systems which employ solar thermal collectors to heat water for domestic purposes. These systems are relatively straightforward, consisting of solar thermal collectors, piping, pumps, a hot water tank, and controllers. The collector area is designed to deliver high solar fractions during the summer, but it typically exhibits lower efficiency in the winter. In Toronto, annual solar fraction, defined as the proportion of energy supplied by the solar thermal system to the total energy required by the load, typically range between 50-70%. This research aims to leverage solar thermal collectors for recharging the ground during the summer months. This approach enables the installation of larger collector areas, improving system performance in the winter, while simultaneously depositing excess energy into the ground during the summer. Notably, this study focuses on a single household located in Toronto, Canada, where the recommended solar thermal collector area is 10 square meters, and the borehole heat exchanger length is 150 meters. Also, it is assumed that four people are living in this house and required energy for heating and cooling of the house are 28000 and 7000 kWh per year, respectively. This approach offers a promising solution to balance seasonal heat transfer to the ground, mitigating the long-term decline in GSHP performance. The study demonstrates that by coupling the solar thermal system with the GSHP, the targeted outcomes are achievable. / Thesis / Master of Applied Science (MASc)

<p>In 2009, the Regional Municipality of Halton and McMaster University initiated a 2-year collaborative study (Georgetown Aquifer Characterization Study-GACS) of the groundwater resource potential of Quaternary sediments near Georgetown, Ontario. As part of that study, this thesis investigated the Quaternary infill stratigraphy of the Middle Sixteen Mile Creek (MSMC) and Cedarvale (CV) buried valley systems using newly acquired core and borehole geophysical data. Multi-parameter geophysical log suites (natural gamma, EM conductivity, resistivity, magnetic susceptibility, full-waveform sonic, caliper) were acquired in 16 new boreholes (16 m to 55 m depth), pre-existing monitoring wells and from archival data. Characteristic log responses (electrofacies) were identified and correlated with core to produce a detailed subsurface model of a 20-km² area to the southwest of Georgetown. Nine distinctive lithostratgraphic units were identified and their geometry mapped across the study area as structure contour and isochore thickness maps. The subsurface model shows that the CV valley truncates the Late Wisconsin MSMC stratigraphy along a channelized erosional unconformity and is a younger (post-glacial?) sediment-hosted valley system. Model results demonstrate the high level of stratigraphic heterogeneity and complexity that is inherent in bedrock valley systems and provides a geological framework for understanding groundwater resource availability.</p> <p>Principal component analysis (PCA) was applied to selected log suites to evaluate the potential for objective lithologic classification using log data. Gamma, resistivity and conductivity logs were most useful for lithologic typing, while p-wave velocity and resistivity logs were more diagnostic of compact diamict units. Cross plots of the first and second principal components of log parameters discriminated silts and clays/shales from sand/gravel and diamict lithofacies. The results show that PCA is a viable method for predicting subsurface lithology in un-cored boreholes and can assist in the identification of hydrostratigraphic units.</p> / Master of Science (MSc)

<p>The sales of Ground Source Heat Pumps in Sweden and many other countries are having a rapid growth in the last decade. Today, there are approximately 360 000 systems installed in Sweden, with a growing rate of about 30 000 installations per year. The most common way to exchange heat with the bedrock in ground source heat pump applications is circulating a secondary fluid through a Borehole Heat Exchanger (BHE), a closed loop in a vertical borehole. The fluid transports the heat from the ground to a certain heating and/or cooling application. A fluid with one degree higher or lower temperature coming out from the borehole may represent a 2-3% change in the COP of a heat pump system. It is therefore of great relevance to design cost effective and easy to install borehole heat exchangers. U-pipe BHEs consisting of two equal cylindrical pipes connected together at the borehole bottom have dominated the market for several years in spite of their relatively poor thermal performance and, still, there exist many uncertainties about how to optimize them. Although more efficient BHEs have been discussed for many years, the introduction of new designs has been practically lacking. However, the interest for innovation within this field is increasing nowadays and more effective methods for injecting or extracting heat into/from the ground (better BHEs) with smaller temperature differences between the heat secondary fluid and the surrounding bedrock must be suggested for introduction into the market.</p><p>This report presents the analysis of several groundwater filled borehole heat exchangers, including standard and alternative U-pipe configurations (e.g. with spacers, grooves), as well as two coaxial designs. The study embraces measurements of borehole deviation, ground water flow, undisturbed ground temperature profile, secondary fluid and groundwater temperature variations in time, theoretical analyses with a FEM software, Distributed Thermal Response Test (DTRT), and pressure drop. Significant attention is devoted to distributed temperature measurements using optic fiber cables along the BHEs during heat extraction and heat injection from and to the ground.</p> / QC 20100517 / EFFSYS2 / Efficient Use of Energy Wells for Heat Pumps