Rock Profiles Research Articles

Geophysical research on the interplays between soil–rock variability and hydrogeological structures: a case study

Understanding the spatial variations in soil–rock profiles is crucial for identifying weathered rock layers and mapping geological structures, particularly in the complex feldspar-rich granitic terrain of Penang Island, Malaysia. This study employs a combination of electrical resistivity and seismic refraction tomographic techniques, along with borehole lithological data, in three distinct areas on the island. Its goal is to provide insights into surficial and subsurface soil–rock characteristics and water-bearing structures within the North Penang Pluton (including a part of the Sungai Ara axis) for sustainable groundwater development, addressing the needs of the region's growing population. The research identifies three distinct geological units at the near-surface: residual soils, highly to moderately weathered/fractured granitic layers and fresh bedrock, each with its hydrogeological properties. Promisingly, the weathered layers offer significant groundwater development potential, with deep weathered and potentially fractured zones exceeding depths of 30 m in the study area. These findings have substantial implications for sustainable groundwater development, especially in tropical hard-rock terrains. In addition, the study underscores the limitations of small geophysical spacings when probing deeper groundwater resources. This knowledge is essential for informed decision-making in water resource management and infrastructure development, addressing the ongoing global challenge of ensuring access to clean water resources amid population growth.

The types, grades and distribution features of geoheritage in China: An inventory

Geoheritage represents typical geological phenomena formed through internal and external geological processes during the Earth's long evolution. It serves as a carrier of crucial information regarding the Earth's evolution, the origin of life, and changes in the geographic environment. Additionally, it is a valuable geological resource for human utilization. In order to provide essential information for the scientific protection and utilization of geoheritage resources, this paper summarizes and further categorizes the types, grades, and distribution characteristics of geoheritage in China based on extensive firsthand data obtained from recent investigations. The results can be summaried in four aspects: (1) As of the end of 2018, a total of 7,267 important geoheritage sites (including global, national, and provincial levels) have been discovered and surveyed in China. Among them, there are 3,154 geoheritage sites of basic geology, 3,935 geoheritage sites of geomorphic landscape, and 178 geoheritage sites of geological disaster. They can be further categorized into 13 classes and 46 sub-classes, such as stratigraphic sections, rock profiles, rock and soil landforms, and earthquake relics. (2) Through expert evaluations and comparative studies, there are 218 Grade I (global level) geoheritage sites, 1,919 Grade II (national level) geoheritage sites, 4,732 Grade III (provincial level) geoheritage sites, and 398 Grade IV (below provincial level) geoheritage sites in China. (3) Geoheritage in China are mainly distributed in five regions: Southwest China, East China, Central China, Northwest, and North China. The geoheritage sites of basic geology are mainly distributed in the Southwest China, Central China, East China, Northwest China, and North China, with the Southwest China having the highest number, accounting for approximately 27%. The geoheritage sites of geomorphic landscape are mainly distributed in the Southwest China, Northwest China, East China, Central China, and North China, with the Southwest China having the highest number, accounting for approximately 29%. The geoheritage sites of geological disaster are mainly distributed in the Southwest China, Northwest China, and Central China, with the Southwest China having the highest number, accounting for approximately 47%.

Uncertainty in Shear-Wave Velocity Profiles

This paper considers the uncertainty in the shear wave velocity (Vs) of soil and rock profiles for use in earthquake site response calculations. This uncertainty is an important contributor to uncertainty in site response, which in turn is an important contributor to uncertainty in earthquake ground motions and in seismic hazard. The paper begins with a discussion of the different types of uncertainty and how they are characterized in probabilistic seismic hazard analysis, and how this differentiation is particularly ambiguous in the case of soil properties. This is followed by a description of the probabilistic models of Vs that are most commonly used in engineering practice, for both generic and site-specific applications. In site-specific applications, the uncertainty in Vs (which is measured by the logarithmic standard deviation or by the coefficient of variation of Vs) is lower than in generic applications, but other elements of the profile model are also different. Next, the paper discusses the issues that arise in characterizing the uncertainty in Vs in site-specific applications using non-invasive surface wave methods and summarizes the insights obtained by comparing the results from multiple blind studies in which the same surface-wave data (and no other site-specific data) were provided to multiple teams of analysts. Finally, the paper provides recommendations on how to characterize uncertainty in Vs for both generic and site-specific applications.

Discontinuity Controlled Deformation Estimation in small Diameter Tunnels

In tunnel construction, tunnel projects are carried out by evaluating the soil and rock profiles obtained from the exploration drillings along the route, groundwater status, and structural elements. In practice, there may sometimes be differences between the geological sections foreseen according to the exploration drillings and the structural elements encountered during tunnel construction. In this study were modeled for the T35-GT1 tunnel by Phases 2D program. For the Ankara-Istanbul High-Speed Train Project, the deformation amounts predicted by numerical analysis and encountered during the T35-GT1 tunnel manufacturing, opened by the conventional method were compared. At the end of the study, it was concluded that when the discontinuity properties are included in the calculation, the deformations realized and the deformations obtained in numerical analysis give values very close to each other.

Soil-Structure Interaction for Building Structures

Abstract: In the analysis of structures subjected to earthquake forces, it is usually assumed that the structure is fixed at the base to simplify the mathematical problem. This assumption leads to gross error in assessment of overall response under dynamic loads. The interaction phenomenon is principally affected by the mechanism of energy exchanged between the soil and the structure during an earthquake. In the present investigation, a multi-storied building which is located in Amaravati is chosen as the study area which consists of different types of soil / rock profiles at different locations. Many high rise structures are expected in future in the new city. Earthquake analysis is carried out when similar structure rests on different types of soils and the results of fundamental time periods, base shears and displacements are compared with the results obtained from fixed base condition.

When AI Meets DIGGS

Drilling and sampling to obtain borehole logs, together with various in-situ testing, are usually performed to determine subsurface soil and rock profiles and their associated engineering propertie...

Petrophysics Analysis for Reservoir Characterization of Cretaceous Clastic Rocks: A Case Study of the Arafura Basin

This study presents petrophysics analysis results from two wells located in the Arafura Basin. The analysis carried out to evaluate the reservoir characterization and its relationship to the stratigraphic sequence based on log data from the Koba-1 and Barakan-1 Wells. The stratigraphy correlation section of two wells depicts that in the Cretaceous series a transgression-regression cycle. The petrophysical parameters to be calculated are the shale volume and porosity. The analysis shows that there is a relationship between stratigraphic sequences and petrophysical properties. In the study area, shale volumes used to make complete rock profiles in wells assisted by biostratigraphic data, cutting descriptions, and core descriptions. At the same time, porosity shows a conformity pattern with the transgression-regression cycle.Keywords: petrophysics, reservoir characterization, Cretaceous, transgressive-regressive cycle

Delineation of Near-Surface Structural Features Suitable for Groundwater Accommodation Using 1-D and 2-D Resistivity Methods in Igarra, Akoko-Edo, Southwestern Nigeria

Electrical resistivity methods using dipole-dipole and Schlumberger configurations of Vertical Electrical Sounding (VES) were carried out to evaluate the near-surface structural and lithological features suitable for groundwater development in parts of Igarra, Southwestern Nigeria. Two profiles with lengths of greater than 350m were carried out. A total of fifteen sounding locations along the profile lines were occupied. Dipole-dipole data were interpreted using DiprofWin software while interpretation of the VES data followed two stages of qualitative and quantitative data interpretation using Resist software. Dipole-dipole interpretation results indicate the occurrence of local fractures while VES interpretation results reveal the typical basement rock profile ranging from topsoil, lateritic sand, weathered front, fractured to fresh basement. The significant variations in terms of persistence and thicknesses of these basement vertical rock profiles were revealed by the geoelectrical correlation panels, which indicate typical basement inhomogeneities over short distances. The local structural domains, the weathered front (where thick) and the fractured basement are demonstrably potential sources of groundwater, at least for domestic and small scale enterprises in this part of Igarra. 
 Keywords: 2-D Pseudosection, Dipole-dipole, Fracture Basement, Vertical Electrical Sounding

Optimizing site-specific geostatistics to improve geotechnical spatial information in Seoul, South Korea

Subsurface soil and rock profiles are commonly interpreted from borehole log datasets. These datasets include three-dimensional spatial coordinate information, layer information, and standard penetration test results. More reliable spatial distribution of target physical properties can be obtained from additional testing at locations characterized by outlier observations and geotechnical uncertainties. At a given site, irregular measurements typically differ significantly from bulk measurements or proximal observations. In this study, a process for optimizing site-specific geostatistics, which uses geotechnical spatial information and applies optimum outlier thresholds with a multi-clustering method, is proposed to incorporate site-specific geo-layer uncertainties and identify their geotechnical value. Optimized geostatistical characteristic information for geological strata boundaries was derived and verified based on a sequential procedure applied to representative test areas in Seoul, South Korea.

Ghost-rock karstification of Devonian limestone flooring the Athabasca Oil Sands in western Canada

This study interprets a new style of ghost-rock karstification at a site in northeast Alberta, western Canada. The karstic area of the Upper Devonian paleotopography was localized at the western end of the Bitumount Trough, a 50 km-long collapse structure that resulted from removal of a 120 m thick interval of salt beds of the Middle Devonian Prairie Evaporite only 200 m below. Ghost-rock karstification developed in massive light grey limestone beds that alternate with chlorite-rich argillaceous intervals, of the Moberly Member, Devonian Waterways Formation. These weathered rock profiles expanded latterly and were deepened by slowly moving hydraulic gradient-driven phreatic groundwater descending along clusters of closely spaced 2–10 cm-wide joints that cross-cut the fracture-shattered limestone beds. The uppermost beds of greyish green chlorite-rich argillaceous limestone were decalcified as the flows along the joint clusters carried insoluble residues consisting of quartz silt mixed with illite-chlorite clays into the substrate. These chlorite-rich insoluble residues accumulated as replacement fabrics within decalcified porous zones of the altered limestone in the substrate. As the joint opening plugged with insoluble residues within the deepened decalcification weathered rock intervals, the alterite zones expanded laterally to form vertical pod-shaped structures. These 5–20 m in diameter and 10–20 m-deep pseudo-sinkhole zones consisting of alterite retained ghost-rock traces of the original limestone strata. This area was subsequently covered by the Lower Cretaceous Athabasca Oil Sands.

Using rodogram function to characterize hurst coefficient in rock profiles

Using rodogram function to characterize hurst coefficient in rock profiles

Characteristics and engineering properties of residual soil of volcanic deposits

Residual soil knowledge of volcanic-sedimentary rock products provides important information on the soil bearing capacity and its engineering properties. The residual soil is the result of weathering commonly found in unsaturated conditions, having varied geotechnical characteristics at each level of weathering. This paper summarizes the results of the research from the basic engineering properties of residual soil of volcanic-sedimentary rocks from several different locations. The main engineering properties of residual soil such as specific gravity, porosity, grain size, clay content (X-Ray test) and soil shear strength are performed on volcanic rock deposits. The results show that the variation of the index and engineering properties and the microstructure properties of residual soil have the correlation between the depths of weathering levels. Pore volume and pore size distribution on weathered rock profiles can be used as an indication of weathering levels in the tropics.

Anisotropy of Rock Profile JRC Values and Its Empirical Formula: A Case Study on Yellow Rust Granite

In this paper, the splitting testing for the Yellow Rust Granite were performed to obtained 14 rock profiles. Based on the Barton’s method, the JRC values of the rock profiles with four different directions were calculated, it is interesting to find that the JRC values of rock profiles are different when tilt directions are different, suggesting that the JRC values presents the characteristics of anisotropy. The traditional empirical formula for estimating the JRC values mainly focused on the two dimensional rock profile and the anisotropy of JRC values are ignored in most studies. For considering the anisotropy of the rock surfaces, this paper presents an empirical formula to evaluate the JRC values, the empirical formula is $$JRC = 1.319(1 + 2.862\tan \beta )D_{f}$$ .

3D point cloud analysis for surface roughness measurement: application of UAV photogrammetry

This paper describes the application of close-range digital photogrammetry through Unmanned Aerial Vehicle (UAV) for rock discontinuity roughness determination. This was possible thanks to the creation of a georeferenced point cloud characterised by 3D information useful for rock mass study. In particular, UAV systems allows producing dense point clouds (with high spatial resolution), suitable to describe the rock surfaces and allowing the surveying of inaccessible outcrops. In fact, the occlusion phenomenon was minimized by means of different acquisition angles. In this context, the computation of the Joint Roughness Coefficient (JRC) was carried out picking several points within the cloud and obtaining rock profiles of the maximum asperity amplitude. Furthermore, we present in the manuscript a rapid and preliminary estimation of the whole rock slope roughness using the freeware CloudCompare code. A 3D roughness model was generated. The JRC results, both manually measured and automatically computed by the code, are comparable. The reliability of the values was confirmed by direct engineering-geological surveys where the surface roughness was calculated using the traditional method of visual comparison to Barton's reference roughness profiles. The paper aims to demonstrate how data derived from UAV processing are, nowadays, so dense and accurate to be able to provide adequate measurements of discontinuity roughness even transcending the problem of the JRC scale effect.

Numerical investigation of spatial aspects of soil structure interaction for secant pile wall circular shafts

Implementation of fast and cost-effective shoring systems has become very necessary to overcome the technical challenges such as variable soil and rock profiles, high groundwater tables and limitations imposed by the built environment. Secant pile wall shoring systems allow the construction of overlapped piles in almost all subsurface conditions. They are constructed in a circular plan layout to form a vertical shaft which provides unique advantages such as compression ring behavior. This paper presents a numerical study to investigate various aspects of the behavior of circular shafts constructed using secant pile walls. The studied aspects include the identification of earth pressure distributions exerted on circular shafts, the impact of excavation of single and multiple holes on the shaft stresses, and the stresses in the shaft in the case of sloping bedrock. A three-dimensional finite element model is developed to conduct the present analyses taking into consideration the actual behavior of soils surrounding the walls. The stress concentrations calculated for circular shafts were seen to vary from the results of the infinite plate with hole solution. The sloping bedrock was also seen to result in significant deviations from the compression ring behavior. A large increase in the maximum compressive stresses and emergence of some significant tensile stress zones were observed for bedrock inclinations larger than 20°. The results presented in this study address some practical design concerns and were considered to be of interest to those involved in design and construction of vertical shafts.

Interface shear behaviour of tunnel backfill materials in a deep-rock nuclear waste repository in Finland

The need for environmental protection and safety in facilities dedicated for the final safe disposal of spent nuclear fuel is paramount. Highly engineered multi-barriers are widely used in such waste containment facilities in order to provide a tight seal for the waste they contain. In Finland, several research studies have been conducted to investigate the feasibility of the final safe disposal of spent nuclear fuel in crystalline bedrock by incorporating the KBS-3V multi-barrier repository concept. As the saturation of the tunnels in a repository progresses, the pre-compressed bentonite buffer may swell and generate very high swelling pressure in the range of 7–15MPa. Such high swelling pressure can cause the upheaval and the compression of the tunnel backfill that would eventually decrease the density of the buffer. For various reasons, the current KBS-3V design suggests that the saturated density of the buffer should be maintained within a narrow range of 1950–2050kg/m3 at all times. As the swelling of the buffer directly influences the saturated density of the buffer, it must be controlled by designing a tunnel backfill that possesses an adequate amount of interface shear strength to sustain any additional pressure that is exerted by the swelling of the buffer. This study presents the findings of a series of direct shear box tests conducted on various tunnel backfill interfaces. Additionally, different types of rock profiles were also tested with the selected backfill materials. Based on the results, it was observed that the interface shear behaviour of different backfill-rock interfaces varied significantly with the surface roughness of the rock, while clay blocks resulted in similar shear behaviour with all the backfill materials.

Seismic behavior of NPP structures subjected to realistic 3D, inclined seismic motions, in variable layered soil/rock, on surface or embedded foundations

Presented here is an investigation of the seismic response of a massive NPP structures due to full 3D, inclined, un-correlated input motions for different soil and rock profiles. Of particular interest are the effects of soil and rock layering on the response and the changes of input motions (frequency characteristics) due to such layering. In addition to rock/soil layering effects, investigated are also effects of foundation embedment on dynamic response. Significant differences were observed in dynamic response of containment and internal structure founded on surface and on embedded foundations. These differences were observed for both rock and soil profiles. Select results are used to present most interesting findings.

The weathering of municipal solid waste incineration bottom ash evaluated by some weathering indices for natural rock

The weathering of municipal solid waste incineration (MSWI) residues consists of complicated phenomena. This makes it difficult to describe leaching behaviors of major and trace elements in fresh/weathered MSWI bottom ash, which was relevant interactively to pH neutralization and formation of secondary minerals. In this study, mineralogical weathering indices for natural rock profiles were applied to fresh/landfilled MSWI bottom ash to investigate the relation of these weathering indices to landfill time and leaching concentrations of component elements. Tested mineralogical weathering indices were Weathering Potential Index (WPI), Ruxton ratio (R), Weathering Index of Parker (WIP), Vogt’s Residual Index (V), Chemical Index of Alternation (CIA), Chemical Index of Weathering (CIW), Plagioclase Index of Alternation (PIA), Silica–Titania Index (STI), Weathering Index of Miura (Wm), and Weatherability index of Hodder (Ks). Welch’s t-test accepted at 0.2% of significance level that all weathering indices could distinguish fresh and landfilled MSWI bottom ash. However, R and STI showed contrasted results for landfilled bottom ash to theoretical expectation. WPI, WIP, Wm, and Ks had good linearity with reclamation time of landfilled MSWI bottom ash. Therefore, these four indices might be applicable as an indicator to indentify fresh/weathered MSWI bottom ash and to estimate weathering time. Although WPI had weak correlation with leachate pH, other weathering indices had no significant correlation. In addition, all weathering indices could not explain leaching concentration of Al, Ca, Cu, and Zn quantitatively. Large difficulty to modify weathering indices correctly suggests that geochemical simulation including surface sorption, complexation with DOM, and other mechanisms seems to be the only way to describe leaching behaviors of major and trace elements in fresh/weathered MSWI bottom ash.

The influence of crystal settling on the compositional zoning of a thin lamprophyre sill: A multi-method approach

We have studied a visibly zoned, thin (< 0.5 m) lamprophyre sill that crops out in the Catalonian Coastal Ranges (NE Spain). The sill is a camptonite composed of large abundant crystals, mainly of clinopyroxene and amphibole, set in a fine-grained groundmass. The mineral chemistry of the different crystal populations indicates that the large crystals are inherited antecrysts incorporated into the magma before emplacement. The major and trace element whole rock profiles are S-shaped, with the development of a marginal reversal in the lower chilled margin. These profiles cannot be explained by normal fractionation of the magma inwards. Instead, the whole rock zoning is controlled by the presence of antecrysts. This is proven: 1) quantitatively, through a trace element model which evaluates the contribution of the antecrysts to the overall composition of the rock, and 2) statistically, through a principal component analysis on the complete trace element data set. The mineral and groundmass compositions show rectilinear compositional profiles, indicating that the magma was emplaced in a single pulse. The accumulation of the antecrysts towards the bottom of the sill, together with the calculation of settling velocities for clinopyroxene and amphibole and cooling velocities for the magma, indicate that the settling of antecrysts during cooling is responsible for the varying proportions of antecrysts and therefore for the whole rock compositional zoning. This study proves that crystal settling is a significant process in triggering compositional zoning of igneous intrusions even at the cm-scale, provided that the magma carries large crystals upon emplacement.

B3 Field mapping

Reconnaissance surveys are usually carried out to establish the main topographical, geological and engineering criteria that will influence the selection and design of a new alignment (e.g. Brunsden et al. 1975) or the key issues that need to be addressed in the case of a road improvement project (environmental and social impact reviews also form critical elements of these surveys). Reconnaissance surveys also allow validation of the desk study interpretations, and provide field information that can then be used to calibrate the desk study outputs. The use of reference conditions to assist in classifying ground conditions originated as an aid to the management of construction contracts in complex/unknown ground conditions (CIRIA 1978). The technique can be used to define the expected engineering parameters and extent of each difficult ground condition, which can then be built into the contract documents. If the ground conditions encountered during construction are different at any particular location to those anticipated, a price adjustment can be made based on the rates provided in the contract for the reference condition actually found. More recently, the technique has been used to assist in the classification of anticipated ground conditions for project feasibility study and design purposes (Baynes et al. 2005; Fookes & Baynes 2008), and is a logical follow-on from terrain modelling and classification (Sections B2.4 & B2.5). By grouping together geological or combined geological-terrain units with approximately similar ground conditions, the technique can be used in the prediction of soil and rock profiles for earthworks schedules and preliminary estimates of quantities. The ground conditions exposed in excavations during construction can be highly variable and sometimes confusing in mountain terrain, and reference condition mapping developed from terrain modelling and classification can help to explain and clarify these variations. The technique can therefore also provide a rationale for …