Champlain Sea Clay (also known as Leda Clay) is a sensitive marine clay that was deposited within the limits of the Champlain Sea transgression during the final retreat of the Laurentide ice sheet. Upon isostatic rebound, the watersheds incised deep river valleys throughout the Ottawa region. These sensitive clay river banks have been shown to be highly susceptible to large retrogressive landslides. A cone penetration testing and hydrogeological program was developed in this thesis to characterize a retrogressive landslide along a creek valley consisting mainly of Champlain Sea Clay. As Champlain Sea Clay has been commonly shown to consist of banded layers, a 2 cm2 piezocone, and 5 cm2, 10 cm2 and 15 cm2 CPTu cones were used to demonstrate that the slightly larger 5 cm2 penetrometer was the most practical size for investigating landslides in Champlain Sea Clay. In doing so, the 5 cm2 cone was capable of high resolution stratigraphic profiling, locating remoulded layers for slip surface detection and characterizing the Champlain Sea Clay landslide near Ottawa. Due to the significant effects of the pore pressure distribution on slope stability and retrogressive behavior, a long term hydrogeological program was initiated which defined the ground water regime and real-time pore pressure data during a retrogressive landslide event. The seasonal change in the ground water regime from rapid snowmelt has shown to be a significant hydrogeological influence on triggering a retrogressive landslide along Mud Creek. With regular monitoring over multiple seasons, the seasonal pore pressure changes can be used to further understand the long term development of retrogressive landslides in Champlain Sea Clay. / Thesis (Master, Civil Engineering) -- Queen's University, 2013-09-27 14:13:40.196

The current approach for using cone penetration test data to estimate soil behavior during seismic loading involves the comparison of the seismic stresses imparted into a soil mass during an earthquake to the penetration resistance measured during an in-situ test. The approach involves an indirect empirical correlation of soil density and other soil related parameters to the behavior of the soil during the loading and does not involve a direct measurement of the dynamic behavior of the soil in-situ. The objective of this research was to develop an approach for evaluating the in-situ behavior of soil during dynamic loading directly through the use of a vibrating piezocone penetrometer. Cone penetration tests were performed in a large calibration chamber in saturated sand samples prepared at different densities and stress levels. A total of 118 tests were performed as part of the study. The piezocone penetrometer used in the investigation was subjected to a vibratory load during the penetration test. The vibratory units used in the investigations were mounted on top of a 1m section of drill rod that was attached at the lower end to the cone penetrometer. Pneumatic impact, rotary turbine, and counter rotating mass vibrators were used in the investigation. The vibration properties generated by the vibratory unit and imparted into the soil were measured during the penetration test by a series of load cells and accelerometers mounted below the vibrator and above the cone penetrometer, respectively. The tip resistance, sleeve friction and pore water pressure were also measured during the test by load cells and transducers in the cone itself. The vibration and cone data were compiled and compared to evaluate the effect of the vibration on the penetration resistance and pore water pressure in the soil mass. The results of the testing revealed that the influence of the vibration on the penetration resistance value decreased as the density and the mean effective stress in the soil increased, mainly because the pore water pressure was not significantly elevated throughout the entire zone of influence of the cone penetometer at the elevated stress and density conditions. An analysis of the soil response during the testing resulted in the generation of a family of curves that relates the soil response during the vibratory and static penetration to the vertical effective stress and density of the soil. The data used to generate the curves seem to agree with the proposed values estimated through the empirical relationship. An evaluation of the effects of the frequency of vibration was also performed as part of the study. The largest reduction in penetration resistance occurred when the input vibration approximated the natural frequency of the soil deposit, suggesting that resonance conditions existed between the input motion and the soil. An energy-based approach was developed to compare the energy imparted into the soil by the vibrator to the energy capacity of the soil. The input energy introduced into the soil mass prior to the reduction in penetration resistance agrees well with the energy capacity of the soil, especially in tests at the low effective stress level where a high excess pore water pressure was observed. / Ph. D.

Downhole seismic testing and seismic cone penetration testing (SCPT) have shown little change since the 1990’s, with essentially the same sensors, sources, test procedures and analytical methods being used. In these tests, the time differences of first-arrivals or other reference points early in the time-domain signals have been used to calculate shear and compression wave velocities in soil and rock layers. This time-domain method requires an operator to pick the first arrival or other reference point of each seismic wave in the time record. Picking these reference points correctly is critical in calculating wave velocities. However, picking these points in time records is time consuming and is not always easy because of low signal-to-noise ratios, especially in the case of shear waves which arrive later in the time record. To avoid picking reference points, a cross-correlation method is sometimes applied to determine travel times of the seismic waves, especially in traditional downhole testing. One benefit of the cross-correlation method is that it can be automated. The cross-correlation method is not, however, appropriate for evaluation other body wave characteristics such as wave dispersion and material damping. An alternate approach is to use frequency-domain analysis methods which are well suited for evaluating time changes between all types of waveforms measured at spatially different points. In addition, frequency-domain methods can be automated and attenuation measurements can also be performed. Examples of such testing procedures with Rayleigh-type surface waves in geotechnical earthquake engineering are the Spectral-Analysis-of-Surface-Waves (SASW) and Multi-Channel-Analysis-of-Surface-Waves (MASW) methods. In this research, an automated procedure for calculating body wave velocities that is based on frequency-domain analysis is presented. The basis for and an automated procedure to calculated body wave dispersion is also presented. Example results showing shear wave velocity and material damping measurements in the SCPT are presented. The objective of this study is to improve downhole seismic tests with boreholes, cone penetrometers or flat-plate dilatometers by developing a frequency-domain analysis method which overcomes many of the disadvantages of time-domain analyses. The frequency-domain method is called the Spectral-Analysis-of-Body-Waves (SABW) method. The SABW method does not require an operator to pick the first-arrival or other reference times. As a result, the shear wave velocities and wave dispersion can be calculated in real time using the interpretation method with an automatic calculation procedure, thus reducing human subjectivity. Also, the SABW method can be used to determine additional information from the dispersion curves such as the material damping ratio and an estimate of soil type based on the dispersion relationship. In this research, field SCPT measurements are presented as an example to illustrate the potential of the SABW method. Measurements with shear waves are highlighted because these measurements are most often required in geotechnical earthquake engineering studies. / text

An essential component for evaluating the performance of a mine site after its closure includes the tracking of water movement through mine waste such as tailings and overburden. A critical element of this evaluation is the measurement of the volume of water stored in the closure landform. The objective of this project was to design a time domain reflectometry (TDR) device that could be used to measure the volumetric water content of a soil profile to depths of 10 to 20 m. Upon completion of this project, the device will be integrated onto ConeTec’s cone penetration testing (CPT) shaft for initially monitoring Syncrude Canada Limited’s northeastern Alberta oil sands mine site. The objective of this project will be achieved through at least two phases of research and development; this thesis concentrates on the first phase. In this phase, research focused on prototype development through laboratory testing to determine appropriate TDR probe geometries and configurations that could be integrated onto a CPT shaft. Considerations also had to be made for protecting the integrity of the probe during field use and mitigating the effects of highly electrically conductive soils common in reclaimed mine sites. A number of different prototype designs were initially investigated in this research, leading to the development of a refined prototype for advanced testing. Testing for the project was carried out first in solutions of known dielectric constants and salinities, and then proceeded to soils with a range of known water contents and salinities. Good quality electrical connections were found to be crucial for generating waveforms that were easy to interpret; bad connections resulted in poor results in a number of cases. Decreased probe sensitivity was observed in response to increased rod embedment within the probe variants. A far greater decrease in sensitivity was seen in the results of the fully sheathed rods, although the sheathing was effective for extending the range of the probe in electrically conductive testing conditions. Despite poor results that were seen in some of the tests, overall the results were promising. In particular, results from the push-test showed that the probe was able to monitor changes in water content with depth.

This thesis evaluates the commonly used geotechnical probing method CPTu, on how different probe configurations impact the resulting evaluated undrained shear strength in soft clay deposits, in comparison to each other and laboratory methods. This is done by performing field investigations on Lindefältet, Södermanlands län, Sweden. Comparison is done on the two Swedish manufacturers of CPTu probes, by different calibration limits, filter types and whether overloading the probe over the calibration limit affects the evaluated undrained shear strength registered. The main conclusions are that one of the manufacturers’ probes registers deviating results in one configuration, that calibration limit has a noticable impact on the results, and that overloading on the probe and filter choice has negliable impact on the results. / I detta examensarbete utvärderas den vanligt förekommande geotekniska sonderingsmetoden CPTu, på hur olika konfigurationer av sonder påverkar den resulterande utvärderade odränerade skjuvhållfastheten i lösa leravlagringar, 9i jämförelse med varandra och med laboratoriemetoder. Detta är genomfört genom fältundersökningar på Lindefältet, Södermanlands län. Jämförelsen gjordes på de två svenska CPTu-tillverkarnas sonder. Detta är gjort med hänsyn till olika kalibreringar av konspetstryck, filtertyper, och huruvida sonden har varit överlastad påverkar den utvärderade skjuvhållfastheten som registreras. De huvudsakliga slutsatserna är att en av tillverkarnas sonder registerar udda värden i en konfiguration, att kalibreringar av konspetstryck har en märkbar påverkan på de resulterande värdena på utvärderade odränerade skjuvhållfastheten, samt att överlastning av sonder och val av filtertyp har liten till omärkbar påverkan på resultatet.

As a consequence of the 2010 – 2011 Canterbury earthquake sequence, Christchurch experienced widespread liquefaction, vertical settlement and lateral spreading. These geological processes caused extensive damage to both housing and infrastructure, and increased the need for geotechnical investigation substantially. Cone Penetration Testing (CPT) has become the most common method for liquefaction assessment in Christchurch, and issues have been identified with the soil behaviour type, liquefaction potential and vertical settlement estimates, particularly in the north-western suburbs of Christchurch where soils consist mostly of silts, clayey silts and silty clays. The CPT soil behaviour type often appears to over-estimate the fines content within a soil, while the liquefaction potential and vertical settlement are often calculated higher than those measured after the Canterbury earthquake sequence. To investigate these issues, laboratory work was carried out on three adjacent CPT/borehole pairs from the Groynes Park subdivision in northern Christchurch. Boreholes were logged according to NZGS standards, separated into stratigraphic layers, and laboratory tests were conducted on representative samples. Comparison of these results with the CPT soil behaviour types provided valuable information, where 62% of soils on average were specified by the CPT at the Groynes Park subdivision as finer than what was actually present, 20% of soils on average were specified as coarser than what was actually present, and only 18% of soils on average were correctly classified by the CPT. Hence the CPT soil behaviour type is not accurately describing the stratigraphic profile at the Groynes Park subdivision, and it is understood that this is also the case in much of northwest Christchurch where similar soils are found. The computer software CLiq, by GeoLogismiki, uses assessment parameter constants which are able to be adjusted with each CPT file, in an attempt to make each more accurate. These parameter changes can in some cases substantially alter the results for liquefaction analysis. The sensitivity of the overall assessment method, raising and lowering the water table, lowering the soil behaviour type index, Ic, liquefaction cutoff value, the layer detection option, and the weighting factor option, were analysed by comparison with a set of ‘base settings’. The investigation confirmed that liquefaction analysis results can be very sensitive to the parameters selected, and demonstrated the dependency of the soil behaviour type on the soil behaviour type index, as the tested assessment parameters made very little to no changes to the soil behaviour type plots. The soil behaviour type index, Ic, developed by Robertson and Wride (1998) has been used to define a soil’s behaviour type, which is defined according to a set of numerical boundaries. In addition to this, the liquefaction cutoff point is defined as Ic > 2.6, whereby it is assumed that any soils with an Ic value above this will not liquefy due to clay-like tendencies (Robertson and Wride, 1998). The method has been identified in this thesis as being potentially unsuitable for some areas of Christchurch as it was developed for mostly sandy soils. An alternative methodology involving adjustment of the Robertson and Wride (1998) soil behaviour type boundaries is proposed as follows:  Ic < 1.31 – Gravelly sand to dense sand  1.31 < Ic < 1.90 – Sands: clean sand to silty sand  1.90 < Ic < 2.50 – Sand mixtures: silty sand to sandy silt  2.50 < Ic < 3.20 – Silt mixtures: clayey silt to silty clay  3.20 < Ic < 3.60 – Clays: silty clay to clay  Ic > 3.60 – Organics soils: peats. When the soil behaviour type boundary changes were applied to 15 test sites throughout Christchurch, 67% showed an improved change of soil behaviour type, while the remaining 33% remained unchanged, because they consisted almost entirely of sand. Within these boundary changes, the liquefaction cutoff point was moved from Ic > 2.6 to Ic > 2.5 and altered the liquefaction potential and vertical settlement to more realistic ii values. This confirmed that the overall soil behaviour type boundary changes appear to solve both the soil behaviour type issues and reduce the overestimation of liquefaction potential and vertical settlement. This thesis acts as a starting point towards researching the issues discussed. In particular, future work which would be useful includes investigation of the CLiq assessment parameter adjustments, and those which would be most suitable for use in clay-rich soils such as those in Christchurch. In particular consideration of how the water table can be better assessed when perched layers of water exist, with the limitation that only one elevation can be entered into CLiq. Additionally, a useful investigation would be a comparison of the known liquefaction and settlements from the Canterbury earthquake sequence with the liquefaction and settlement potentials calculated in CLiq for equivalent shaking conditions. This would enable the difference between the two to be accurately defined, and a suitable adjustment applied. Finally, inconsistencies between the Laser-Sizer and Hydrometer should be investigated, as the Laser-Sizer under-estimated the fines content by up to one third of the Hydrometer values.