Projekt ”Förbifart Stockholm” startade år 2009 och är en av tidernas största projekt i Sverige. Examensarbetet tar upp den geotekniska, hydrologiska och geologiska aspekten kring projektet ”Förbifart Stockholm”. Mer exakt så studerades sättningar på grund av grundvattensänkningar, men också så kallade pågående sättningar. Sättningar undersöktes och beräknades i ett utvalt område i Sätra. Beräkningarna gjordes med olika djup på grundvattensänkningar för att undersöka sättningarnas storlek. Därefter beräknades det hur lång tid det tog för att uppnå slutsättningen.  En noggrann analys av det utvalda området gav en bättre förståelse till varför det pågår sättningar i dagsläget utan att det skett något arbete än. När ett område med pågående sättningar utsätts för en grundvattensänkning så kan det leda till stora markrörelser. Ur resultatet av beräkningarna undersöks det om sättningarna är så pass stora att intilliggande byggnader kan skadas. Om så är fallet måste man minska grundvattensänkningen. Resultatet visade att sättningarna blev så stora att det fanns en risk för skador. Därför har det bestämts att en infiltrationsanläggning ska användas. Med hjälp av den kan en större grundvattensänkning förhindras och på så sätt förebygga skadliga sättningar. Skadliga sättningar kan vara väldigt kostsamma och det vill man undvika vid ett projekt som beräknas kosta ca 28 miljarder kronor. / The project “Förbifart Stockholm” started year 2009 and is one of the biggest projects in Swedish history. The Bachelor takes on the geotechnical, hydrological and geological aspect in project “Förbifart Stockholm”. More exactly it is a study of subsidence due to groundwater lowering, but also so called ongoing subsidence. Subsidence’s were examined and calculated in a chosen area in Sätra. The calculations were done with different groundwater lowering to examine how big the subsidence was. Thereafter new calculations were made to see how long time it took to reach the final subsidence. A thorough analysis of the area in Sätra gave a better understanding to why there are ongoing subsidences when the tunnel digging has not begun yet. When an area with ongoing subsidence undergoes a groundwater lowering it could result in a big ground movement. From the result of the calculations there is an investigation to see if the subsidence is so big it could cause damage to nearby buildings. If that was the case then a method to reduce groundwater lowering must be found. The result indicates that the subsidence could become so big that there is a chance of damaging buildings. Therefore it has been decided to install an infiltration device. The infiltration device helps preventing deeper groundwater lowering and avoiding harmful subsidence. Harmful subsidence can become very costly and needs to be avoided in a project that costs 28 billion Swedish crones.

archives@tulane.edu / Salt basins are complex structural systems, showing genetic relationships between salt structures, faults, and variable sediment depositional patterns. The dynamics of salt-fault interaction, the role of shale deformation, and the influence of salt evacuation on surface features have been poorly understood. A link between all these processes is the throw history of faults adjacent to and within a salt basin. In this dissertation, I interpret industry well logs and 3D seismic data from the Terrebonne Salt Withdrawal Basin (TSWB) of southeastern Louisiana, to understand these processes. The methodology includes the use of fault throw maps, throw variations along strike and with depth, and sediment expansion indices to understand fault kinematics adjacent to sediment loads and mobile material, i.e., salt or shale. I address the histories of three faults along the northern margin of the TSWB: the Lake Boudreaux, Montegut, and Isle de Jean Charles faults. Each shows Miocene and Quaternary active phases correlated with sediment loading, separated by relative inactivity during the Pliocene. The pattern of Quaternary activity and the surface projections of these faults are consistent with a fault-controlled pattern of wetland loss, suggesting that faults in southeastern Louisiana are active. Isle de Jean Charles fault and the Lake Boudreaux fault interact with the Bully Camp and Lake Barre Salt stocks, respectively. Each stock is interpreted to have grown by a different diapiric mechanism, consistent with different spatial patterns of throw variation on the two faults, despite similar temporal histories. Throw on the Isle de Jean Charles fault increases towards the Bully Camp stock, suggesting deformation inside and outside the stock. In contrast, a decrease in the throw on the Lake Boudreaux fault and an increase in diameter of the Lake Barre stock indicate that deformation exists only within the stock. Additionally, this dissertation considers throw patterns along the southern margin of the TSWB, showing that faults linking the Dog Lake and Caillou Island salt stocks are affected by shale deformation adjacent to salt. These results show that studies of fault-related subsidence and wetland loss in coastal Louisiana need to include observations from nearby salt structures. / 1 / Akinbobola Akintomide

Southeast Louisiana is susceptible to the impact of subsidence due to natural and anthropogenic processes including sediment compaction and loading, fluid withdrawal, and faulting. Subsidence rates in Southeast Louisiana are higher than anywhere else in the United States, and the impact of subsidence rates on industrial complexes has not been studied. Spatial interpolation methods were analyzed to determine the best fit for subsidence rates and to create a predictive surface for the lower Mississippi River Industrial corridor (LMRIC). Empirical Bayesian kriging, ordinary kriging, universal kriging, and inverse distance weighted interpolation methods were applied to the 2004 National Oceanic and Atmospheric Administration (NOAA) published Technical Report #50 dataset and cross-validation methods were utilized to determine the accuracy of each method. The mean error and root mean square error were calculated for each interpolation method, then used to detect bias and compare the predicted value with the actual observation value. Cross-validation estimates are comparable for each method statistically and visually; however, the results indicate the empirical Bayesian kriging interpolation method is the most accurate of the methods using the lowest mean error and root mean square error scores. Digital elevation models for the years 2025, 2050, and 2075 were developed based on the predictive surface of subsidence rates using the results from the empirical Bayesian kriging interpolation method. Results indicate that by 2025, 31.4% of landmass in the LMRIC will be below 0 m NAVD88, with 40.4% below 0 m NAVD88 by 2050, and 51.8% by 2075. Subsidence rates in the LMRIC range from approximately 16 mm to less than one mm per year. Nine of the 122 industrial complexes located in the LMRIC are estimated to be below 0 m NAVD88 by the year 2075. Limited economic impacts can be inferred based on the number of facilities impacted; however, service disruptions due to subsidence impacting infrastructure surrounding these industrial complexes would have catastrophic economic impacts on a regional, state, and national level.

Permafrost deformation is expected to increase due to climatic perturbations such as amplified air and soil temperatures, resulting in permafrost thawing and subsequent subsidence. Palsas and peat plateaus are uplifted ice-rich peat mounds that experience permafrost subsidence. This is due to the uppermost layer of permafrost, known as the Active Layer (AL), that seasonally thaws and freezes. Interferometric Synthetic Aperture Radar (InSAR) is an interferometric stacking technique successfully applied over permafrost regions when monitoring ground subsidence. The Small Baseline Subset (SBAS) technique is based on interferograms produced by stacking Synthetic Aperture Radar (SAR) acquisitions with small normal baselines. In this study, seasonal Sentinel-1 SAR C-band data obtained during June, July, August and September (JJAS) was used to generate seasonal Line of Sight (LoS) deformation time series of palsas and peat plateaus in Tavvavuoma (Sweden) by using the SBAS technique. Chersky (Russia) has documented permafrost subsidence and was used as a reference site. Findings include that seasonal stacks with short normal baselines generated more robust results than inter-annual stacks with longer normal baselines and temporal data gaps. No instances of pronounced subsidence were reported during JJAS. Nevertheless, minor subsidence during the early season and negative development trends were identified in the Tavvavuoma 2020 andChersky 2020-2021 stacks, respectively. Increased subsidence during the mid-and late thaw season was detected. The SBAS technique performed better and resulted in less temporal and seasonal decorrelation in areas above the tree line (Tavvavuoma) compared to the lowlands in the forest-tundra (Chersky). The challenge lies in whether surface subsidence of palsas and peat plateaus in sporadic permafrost regions experience irreversible long-term changes or seasonally cyclic changes in the permafrost ground regime. Future studies are recommended to implement annual intervals, including winter images over Tavvavuoma.

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<p>The modern coastline provides few clues as to the ancient harbour configuration since Kalamianos has been partially submerged by > 6 m of relative sea-level rise since the Early Helladic. In 2009, a detailed marine geophysical survey and underwater diver search was conducted in the inshore waters to identify potential anchorage sites and to examine evidence for coastal subsidence. Single-beam bathymetry and magnetic gradiometer data were acquired and integrated within a detailed digital bathymetric model (DBM).</p> <p>The DBM revealed two submerged beachrock platforms (BR-1, BR-2) paralleling the modern shoreline and a submerged isthmus connecting the mainland with small island 200 m offshore. The BR-1 platform (3.5-3.7 m depth) contained abundant Late Helladic (LH; 1300-1190 BC) pottery sherds (30-50%) and wood charcoal fragments.¹⁴C dating of the extracted charcoal yielded an AMS ¹⁴C uncalibrated age of 3250±40 BP, consistent with the LH ceramics. The BR-2 platform (5.8-5.9 m depth) contained less pottery (<20%) and included well-preserved fragments of Early Helladic (EH) jars.</p> <p>The beachrock elevations and ¹⁴C and pottery ages were used to reconstruct a sea level curve and a series of paleogeographic maps of the EH to LH shorelines. The presence of abundant pottery and wood charcoal in the BR-1 beachrock indicates that shipping activity during the LH was focused at the south end of the site in a western harbour basin. This is supported by magnetic gradiometer results, which identified several magnetic anomalies in the western harbour basin. These were investigated by diver search and found to be concentrations of ship ballast stones (mainly andesite) and clay pottery.</p> / Master of Science (MSc)

A mathematical model is developed for quantification of aquifer deformation due to ground-water withdrawal and, with some modifications, is potentially applicable to petroleum reservoirs. A porous medium saturated with water is conceptually treated in the model as a nonlinearly viscous fluid continuum. The model employs a new three-dimensional extension, made in this thesis, of Helm's poroviscosity as a constitutive law governing the stress-strain relation of material deformation and Gersevanov's generalization of Darcy's law for fluid flow in porous media. Relative to the classical linear poroelasticity, the proposed model provides a more realistic tool, yet with greater simplicity, in modeling and prediction of aquifer movement. Based on laboratory consolidation tests conducted on clastic sedimentary materials, three phases of skeletal compaction are recognized. They are referred to as "instantaneous compression", "primary consolidation" and "secondary compression" according to Terzaghi and Biot's theory of poroelasticity. Among the three modes of consolidation, material behavior during the secondary compression phase has a nonlinear stress-strain relationship and is strongly time-dependent, exhibiting a phenomenon often known as "creep". In poroelasticity, the primary and secondary compressions have been conceptually considered as two separate physical processes that require two sets of material parameters to be evaluated. In contrast, the proposed poroviscosity model is a unified theory of time-dependent skeletal compression that realistically describes the physical phenomena of sediment compression as one single transient process. As a general model, two sets of governing equations are formulated for Cartesian and cylindrical coordinates, respectively, and allow for mechanical anisotropy and the assumption of principal hydraulic directions. Further simplifications of the governing equations are formulated by assuming mechanical isotropy, irrotational deformation and mechanical axisymmetry, which are more suitable for field applications. Incremental forms of the governing equations are also provided. / Ph. D.

The use of delayed drainage in land subsidence modeling greatly complicates model calibration, particularly when the thickness of the fine-grained interbeds varies throughout the modeled region. This thesis documents two separate projects (chapters) related to the use of delayed drainage in groundwater flow and subsidence modeling with parameter estimation. The overall goal of these projects was to better understand how delayed drainage affects accurate parameter estimation and how it is currently affecting the subsidence processes occurring in Las Vegas Valley. Chapter 1 describes an investigation on the value of subsidence data for groundwater model calibration considering delayed drainage. The calibration results of 13 hydraulic parameters of a synthetic conceptual model evaluated for 24 test cases indicate that (1) the inverse of the square of the observation values is a reasonable method to weight the observations, (2) spatially abundant subsidence data typically produce superior parameter estimates even with observation error under constant and cyclical pumping, (3) when subsidence data are limited and combined with drawdown data, outstanding results are obtained for constant pumping conditions. However, for cyclical pumping with observation errors, the best parameter estimates are achieved when multiple years of seasonal subsidence data are provided. The results provide useful suggestions for real-world calibration problems. Chapter 2 outlines the development of an updated flow and subsidence model for Las Vegas Valley covering the entire period of development of the basin. The new model includes a subsidence package that takes into account delayed drainage of fine-grained interbeds. Previous models used subsidence packages that assumed instantaneous equilibration of heads across all hydrogeologic units. The new model resulted in an agreement with measured water-level and improved the simulation of land subsidence. The analysis shows that the typical residual subsidence in Las Vegas Valley can be accurately simulated by incorporating delayed drainage in a long-term model. The study also indicates the need for more sophisticated modeling practices that use delayed drainage with parameter estimation processes to accurately calibrate flow and subsidence models. / Master of Science