Sandy Layers Research Articles

Subsidence and measures in the polders of the Netherlan ds

AbstractThe Netherlands consists for 65% of polders. Impoldering activities started in the beginning of the 11th century with impoldering of coastal lowlands. In the 13th century, a start was made with reclaiming of lands gained on the sea and since early 16th century with draining of lakes. Up to several metres in depth, soils consist primarily of peat and or clay. Underneath is a thick sandy layer, with lenses of clay. Especially in peat polders, subsidence and oxidation have been significant, up to 5 m, and is still going on. In clay polders, most of the subsidence took place in the first decennia after reclamation. Maximum subsidence in these polders has been 1.25 m. Over centuries, various measures have been taken to cope with the subsidence problems. These measures consist first of all in water management measures related to management not only of the subsidence process, but also of special measures with respect to buildings, structures and infrastructure. The paper presents a review of the subsidence process in the different types of polders, as well as of measures that over the centuries have been taken to cope with the developments in the polders and to cope with subsidence problems.

Paleo-climatic control on recharge and fresh-salt groundwater distribution in the Red River delta plain, Vietnam

Paleo-climatic induced sedimentation controls present-day recharge and the fresh-salt groundwater distribution in Quaternary delta systems. During sea-level highstands, marine clays with saline pore water were deposited and are interbedded with aquifers of coarse-grained sandy fluvial and shallow marine deposits, laid down during lowstands. The low-permeable marine layers may inhibit recent recharge to deeper aquifers, and thereby limit sustainable use of these freshwater resources. This phenomenon has been investigated in the Red River delta plain, using geophysical borehole logging, transient electromagnetic soundings, groundwater chemistry, stable isotope analysis and 3H and 14C dating of groundwater. Results reveal that marine saline pore water is still present in the Holocene marine clays, implying that fresh water has not entered the clays since their deposition. Therefore, recharge within the delta plain is not occurring and the deeper aquifers are hydraulically disconnected from the upper sandy layers. Today, recharge only occurs from the hinterland. Recharge during the last glacial period has flushed saline pore water from Pleistocene marine clays, but these clays were again affected by saline water during the Holocene transgression. The use of the groundwater resources in the delta plain must be adjusted to the present recharge to be sustainable.

Seismic site characterization baseline data for microzonation and site response analysis of Otuasega Town, Bayelsa State, Niger Delta region of Nigeria

This study presents the findings of a comprehensive geotechnical and seismic site investigation conducted at Otuasega Town located in Bayelsa State within the Niger Delta region of Nigeria. Subsurface exploration involved advancing 10 boreholes to 30 m depth using hollow stem auger drilling. Continuous disturbed and undisturbed soil sampling was performed at 1.5 m intervals for detailed geotechnical testing. Laboratory tests on the recovered soil samples established the index properties, classification, densities and consistency limits of the stratified deposits. The subsurface profile comprised alternating layers of clay, silt and sand typical of deltaic sediments, with the clay fractions exhibiting medium to high plasticity. Shear wave velocity (Vs) profiling using Multichannel Analysis of Surface Waves (WASW) techniques categorised the site predominantly as Site Class C and D based on international standards. The Standard Penetration Test (SPT) N-values ranged from 5 to 10, indicating soft normally consolidated clay conditions typical of the Niger Delta region. Predictive empirical models developed from the field and lab data showed strong correlations for estimating key geotechnical parameters such as SPT blow count, Vs and liquefaction resistance. Ground response analyses using the Vs and SPT data indicated significant site amplification potential, with peak ground accelerations up to 1.5 times the bedrock motion. Liquefaction analysis based on the empirical SPT-based methods revealed a high potential for liquefaction in the sandy layers, especially under strong earthquake shaking. The study characterized the complex sedimentology and provided baseline information for seismic microzonation and site-specific ground response analyses to advance understanding of geohazards in this delta environment.

Desertic siliciclastic stromatolites in the Upper Jurassic Guará Formation from southwestern Gondwana: Trapping and binding in a non-marine setting

Siliciclastic stromatolites are rare in the geologic record, and their occurrence recorded in the literature is restricted to marine and coastal environments. The Upper Jurassic Guará Formation, from the Paraná Basin in southern Brazil, hosts unique non-marine siliciclastic stromatolites, providing a rare opportunity to study trapping and binding mechanisms by microbial mats in a continental setting. These microbialites occur interbedded with eolian and fluvial facies. The structural layering of the stromatolite domes is formed by the intercalation of sandy layers, resulting from trapping and binding of siliciclastic grains by microbial mats and in situ precipitation of amorphous to cryptocrystalline silica, which directly replaced the microbial colonies. The silica layers contain partially preserved spherical to ovoid bodies interpreted as colonies of coccoid microorganisms. These siliciclastic stromatolites were formed due to a specific balance of environmental factors, namely water chemistry and sediment supply, which enhanced the processes of trapping and binding and in situ precipitation. They record the presence of microbial life in a non-marine, silica-rich, fluvial-eolian environment in which there were no previous published occurrences of agglutinated stromatolites. These specimens record macroscopically identifiable evidence of microbial life in a continental environment that must be accounted for in the search for ancient life on Earth and Mars.

Scours effects on the lateral bearing capacity of monopile-friction wheel composite foundations in sand-overlaying-clay deposit

The monopile-friction wheel composite foundation is recognized as an innovative offshore wind turbines (OWTs) foundation type, distinguished by its superior lateral bearing capacity and resistance to local scouring. In order to investigate the influence of local scour in sand-overlaying-clay deposit on the lateral bearing capacity of this new type of composite foundations, a series of numerical simulations are conducted to explore the effects of potential parameters including different scour parameters, overlying sandy layer thickness and loading point height on the lateral bearing performance. The results indicate that the greatest reduction in lateral bearing capacity of the composite foundation due to scour depth can reach approximately 35%, while the scour extent and angle have relatively small effects. Moreover, the lateral bearing capacity of the composite foundation increases with the thickness of overlying sandy layer. Local scour and the sand layer thickness also affect the lateral deformation and the soil resistance along the pile shaft. Furthermore, as the loading point height increases, the lateral resistance of the composite foundation decreases rapidly. These findings offer valuable insights for the design of monopile-friction wheel composite foundations in sand-overlying-clay deposits.

Coastal flooding in Kołobrzeg (Kolberg) area, southern Baltic Sea, in the light of historical and geological data

The Baltic Sea is not a typical tsunami area, but there are reports of coastal flooding, with its traces preserved in deposits from Germany, Finland and Sweden, and more recently from Poland. In this study an attempt was made to verify historical and legendary accounts of the ‘Sea Bear’ (‘der Seebär’) phenomenon. In the descriptions of folk accounts, the phenomenon has the features such as suddenness, speed, short duration, independence from the atmospheric conditions on land and sea. The search for coastal flooding deposits was conducted around the town of Kołobrzeg (Kolberg), located on the southern coast of the Baltic Sea. For the study area in chronicle record exist information about two events (17 September 1497 and 1 March 1779). For both events no record has been found in geological profiles, probably due to strong anthropogenic transformation of the subsurface layers. However there is quite precise information from chronicle records on the extent of the event from 17 September 1497 and on the thickness of the sandy layer left by the flooding. Based on this information in the Kołobrzeg area the range of the sand layer was 1400 m from the seashore, and its thickness locally reached approximately 10 cm. The flood height estimated according to the above-presented assumptions was 4.9 m a.s.l. In the Baltic Sea area, coastal flooding is possibly due to atmospheric forcing which can be responsible for an external waves event and devastating long waves, which have the same spatial and temporal scale as typical tsunami waves.

Prediction of emergency-free operation of production wells with a horizontal termination under conditions of high removal of mechanical impurities on the example of the Severo-Komsomolskoe field

Relevance. As readily available oil reserves are developed and production technologies develop, oil and gas companies are gradually moving to the development of previously unprofitable assets. Over the past five years, several oil-and-gas condensate fields with oil rims have been put into operation in Western Siberia. Their development is further complicated by oil high viscosity and poor cementation of the reservoir rocks. Low values of critical drawdown do not allow oil to be produced without destruction of the productive formation, and mechanical impurities entering the well lead to spillage of perforation intervals and downhole equipment failures. The use of mathematical modeling in relation to the operation of wells in the conditions of the removal of mechanical impurities will make it possible to control production and select the optimal well operation mode. Aim. Forecasting the trouble-free operation of a production well under conditions of high removal of mechanical impurities. Objects. Producing oil wells; the subject of the study is the movement of solid particles in the wellbore of a production well, the relationship and dependence of formation of sand plugs on the operating parameters of the well. Methods. Theoretical research methods – analysis (analysis of models for calculating the critical flow velocity in a horizontal pipe (calculation of the critical velocity in a single-phase flow; calculation of the critical velocity in a multi-phase flow; calculation of the critical velocity based on the balance of forces)) and modeling (simulation of work wells with the removal of mechanical impurities). The totality and combination of these methods are adequate to the goals and objectives, the object and subject of the study of this work. Results. The problem of sand production is typical not only for fields that are in the late stages of development, but also for fields that have recently been put into operation. Sand shows up are a complicating factor in the operation of wells at the Severo-Komsomolskoe high-viscosity oil field located in Western Siberia. The main object of development of the studied field is a weakly cemented sandy layer. Oil production in such difficult areas requires a very careful approach to the choice of development system, to the selection of methods to deal with complications, including the choice of the right method to limit sanding. However, regardless of the approach taken to solve the problem of sand production, some rock will still flow into the well. To prevent the formation of sand plugs, it is necessary to understand the nature of the movement of solid particles along the wellbore. It is possible to assess whether a well is capable of carrying out solid particles from a horizontal section using modeling in specialized software products. Modeling of the well operation, taking into account the influence of mechanical impurities, made it possible to solve the following problems: 1) determine the fluid to carry rock particles out of the horizontal section; 2) identify the areas in which there is a risk of sand plugs; 3) present the dependence for calculating the critical speed for high-viscosity oil with different water cut; 4) assess how the water cut and gas factor affect well operation in conditions of high removal of mechanical impurities; 5) calculate the time of formation of sand plugs.

Sedimentary and hydraulic characterization to identify hydrofacies in Barreiras Formation, Rio de Janeiro state - Brazil

The use of analogous outcrops in characterizing hydrogeological heterogeneities is widespread worldwide. It is a powerful tool for sediment characterization and determination of hydraulic parameters in rural and urban areas lacking hydrogeological information. This study investigates and characterizes the depositional and post-depositional factors that control the quality of the porous aquifer of the Barreiras Formation, Campos Basin, Rio de Janeiro, Brazil. The integrated analysis between petrological and hydraulic parameters in two outcrops analogous to the Barreiras aquifer demonstrated the role of post-depositional processes, which altered the original deposition conditions. The two outcrops are predominantly composed of sandy and muddy facies, with hydraulic conductivity ranging between 10−4 to 10−5 cm/s and 10−5 to 10−8 cm/s, respectively. This allowed the definition of two hydrofacies, formed by sandy layers as reservoirs and by muddy layers acting as hydraulic barriers. In this context, the Barreiras Formation can be characterized as a poor aquifer, differing from the typical braided fluvial deposits. This evidence draws attention to the indiscriminate use of typical sedimentary models in environments with a high rate of chemical-biological weathering, not only in underground flow models but also in studies of underground resources protection and exploitation, such as the Barreiras aquifer, which consists of one of the main water sources for public, industrial and agricultural supply.

On the radiometric significance of glauconies in studies of provenance: An example of the quaternary marine sequences of the Rio Grande Cone (Pelotas basin, southern Brazil)

The sediments of the Pleistocene-Holocene marine sequences of the Rio Grande Cone (RGC) (offshore Pelotas Basin, southernmost Brazilian Margin) are dominantly composed by muddy facies with thin interspersed sandy layers containing abundant very fine-to coarse green grains, heavy minerals assemblage, shards and planktonic foraminifera. These components contribute for a better understanding of the RGC filling during the Pleistocene-Holocene. However, the aim of this work was focused in the radiometric dating of the green grains as tool for provenance studies in marine sedimentary sequences. Based on Electron Microprobe, Scanning Electron Microprobe, Transmission Electron Microprobe and optical analysis the green grains occur as: (01) yellowish-green grains with smooth surfaces, low K2O and moderate Fe2O3 contents, (02) pale green grains with surfaces slightly fractured with moderate K2O and Fe2O3 contents, and (03) dark green grains characterised by fractured (cracked) surfaces and high of K2O and Fe2O3 contents. These characteristics classified them as glauconitic minerals ranging from glauconitic smectite to glauconitic mica (glauconite) indicating the first (nascent) and intermediate (slightly-evolved and evolved) stages of the glauconitization process. K–Ar radiometric dating indicated ages from 33.2 ± 0.99 to 6.69 ± 0.54 Ma corresponding from Rupelian Stage (Oligocene) to Messinian Stage (Miocene) to these grains. Considering these glauconitic grains within a Quaternary sequence, an allochthonous (detrital) origin was attributed whose probable source areas were older sedimentary sequences exposed on the seafloor along fold-and-thrust belts related to the gravitational collapse of the RGC depocentre. After eroded the glauconitic minerals probably were distributed by countourite currents and deposited within the Quaternary deposits of the RGC.

Large-Scale Levee Breach Experiments With Foreshores

Coastal flood risk is expected to increase substantially in the near future. Main drivers are climate induced sea level rise, increased storm surge and land subsidence. Meanwhile, land subsidence compounds to increased extreme water levels as more land is susceptible to flooding. Without coastal defense or adaptation 50% more people are exposed to flooding than present day (Kireczi et al., 2020). Coastal regions are currently primarily protected by hard (grey) flood defenses such as storm surge barriers, seawall, dikes and dunes. Periodically, strengthening of these grey structures is necessary to comply with current or updated safety standards. For dikes, conventional strengthening methods are crest heightening or (base) widening. However, these methods have structural and financial limits. Instead, more sustainable methods are explored in which nature also plays a larger role. These solutions are known as Nature based Solutions (NbS). For flood protection, tidal marshes have gained great interest as a Nature based Solution in the past two decades. Tidal marshes provide a lot of ecosystem services (Barbier et al., 2011). One such service is flood protection, attributed to wave attenuation (Vuik et al, 2016). A secondary effect is flood impact reduction (Zhu et al., 2020) due to the high elevation of tidal marshes limiting the inflow to the breach. Secondly, the tidal marsh can act as a sill in front of the breach when water levels drop below the tidal marsh level. To quantify the effect of tidal marshes on flood impact the breaching process in combination with a tidal marsh (or foreshore in general) needs to be understood. In this study we performed a large-scale physical dike experiment where we breached a dike seven times. Three tests are done without a sediment layer in front of the dike (no foreshore), two with a sandy layer (sandy beach) and two with a clay layer (tidal marsh without vegetation). From the experiments we gain insight into differences in the dike breaching process with and without an erodible sediment layer in front of the dike

Sediment production process and hydraulic characteristics of ephemeral gully erosion in granite hilly area

Ephemeral gully (EG) erosion represents the early stage of large-scale gully (locally named as “Benggang”) development on Ultisols in the granite hilly area. However, the EG erosion process and the mechanism underlying sediment production have not been fully elucidated. In this study, a series of field scouring experiments were conducted under different flow discharge levels (10, 15, 20, 25, and 30 L·min−1), and the primary EGs in three typical soil layers with different weathering degrees (red soil layer (RL), transition layer (TL), and sandy layer (SL)) was dynamically monitored. The results indicated that the ratio of width to depth of the EGs rapidly decreased as the flow discharge increased. At 30 L·min−1, the average sediment yield and transport rate (Sr) of the SL were 4.85 and 5.39 times, greater than those of the RL, respectively. The sediment particles were concentrated within the 1–2 mm particle size range, accounting for over 35 %. In addition, the mean weight diameter of the sediment particles in the RL was the largest. The sediment distribution characteristics did not respond to flow changes but were affected by EG morphological changes. With increasing flow discharge, the flow shear stress and stream power increased. Further analysis revealed that the coupling effect of flow hydraulic characteristics and EG morphological evolution drove the EG erosion sediment production process, and the Sr of the SL was highly sensitive to flow discharge changes. The soil disintegration rate was an internal factor that directly affected soil loss in the EGs, with a path coefficient of 0.71. The bulk density, organic matter content, and sand content were all indirect influencing factors. The RL exhibited greater anti-erodibility than the other layers and could serve as an effective protective layerfor granite hilly areas. These findings provide a theoretical basis for improving soil loss management systems.

Effect of Soil Moisture Content on the Shear Strength of Dicranopteris Linearis-Rooted Soil in Different Soil Layers of Collapsing Wall

The occurrence and development of Benggang is closely related to the decreased shear strength of collapsing walls. Plant roots can improve the soil shear resistance, and their soil reinforcing effect is restricted by soil moisture content (SMC). However, the effect and mechanism of SMC on the shear properties of rooted soil with different soil properties remain unknown. Therefore, the dominant soil erosion-resistant plant Dicranopteris linearis was selected as the research object, and shear tests were conducted to determine the shear strength response of rooted soil to SMC in the lateritic layer (LL), sandy layer (SL) and detritus layer (DL) with SMCs from 15% to 30%. The results showed that, compared with 15% SMC, the average decrease in shear strength of 30% SMC in the LL, SL and DL rooted soil were 17.37%, 21.96% and 23.36%, respectively. The rooted soil cohesion changed with increasing SMC in a binomial function, and the optimal SMC in the LL was 22.78%, which was higher than that of the SL (19.67%) and DL (18.39%). The cohesion increment of rooted soil weakened with increasing SMC, and the decrease was greatest in the SL. When the SMC increased from 15% to 30%, the internal friction angle of the rooted soil decreased by 34%, 11% and 12% in the LL, SL and DL, respectively. The Wu and Waldron’s model (WWM) correction parameters k′¯ of the LL, SL and DL were 0.59, 0.14 and 0.05, respectively. With the modified WWM, a new prediction model for the shear strength of rooted soil based on SMC was established. In short, a high SMC weakened the mechanical effect of Dicranopteris linearis-rooted soil, especially in the SL and DL of the collapsing wall, and attention should be given to drainage facilities when treating Benggang erosion.

Geophysical investigation of aquifer flow unit characteristics in northern parts of Akwa Ibom State, Southern Nigeria

The heterogeneous nature of the aquifer system poses significant challenges to both aquifer delineation into hydraulic flow units (HFUs) and the assessment of groundwater flow efficiency. This heterogeneity leads to changes in aquifers’ hydraulic parameters, which include porosity, flow and storage capacities, permeability, flow Zone Indicator (FZI) and aquifer quality index (AQI). Thus, the key aim of this study is to examine aquifer flow unit characteristics in Ikot Ekpene and Obot Akara municipalities by categorizing the units into distinctive HFUs via the combined application of the electrical resistivity technology (ERT), Stratigraphic Modified Lorenz Plot (SMLP) and Flow Zone Indicator (FZI) techniques. The area is shown to comprise successions of three to four sandy layers with minor clay interbeddings at few locations from the ERT results. The aquifer units are found in layers two and three respectively at depths of between 1.6 and 30.2 m with 30.2–89.0 m thickness. The results of the FZI technique identify two distinct HFUs in the area with respective discrete rock typing (DRT) values of 14 and 15 whereas that of the SMLP method reveal 5 unique HFUs, each characterised by similar flow characteristics. The delineated flow units from the SMLP results are classified as conductors with a fair efficiency ranking. This ranking seems to correlate with the DRT results for the delineated unconsolidated sandy and gravelly sand aquifers, which are shown to be perfectly heterogeneous. These findings from this maiden study in the area are very promising and provide useful insights on groundwater flow characteristics in the area to assist groundwater resource regulating authorities and policy makers in making decisions on appropriate location of new water boreholes to satisfy the mushrooming water needs of the local population.

Secondary and micronutrient application effects on corn fertilized for different yield goals under highly weathered soil conditions

AbstractHighly weathered soils have low native fertility; thus, optimum nutrient management is critical, especially for a high‐input crop such as corn (Zea mays). Field studies were established in Plains and Tifton, GA, to assess secondary nutrient (SN; Mg, Ca, and S) and micronutrient (MN; B, Zn, Mn, Fe, Cu, and Mo) application effects on corn fertilized with primary nutrients (PN; N, P, and K) to achieve 12.5 Mg ha−1 (low) and 25.1 Mg ha−1 (high) yields. Both Plains and Tifton have Ultisol soil. However, the Tifton soil has a 30‐cm top sandy layer, and the Plains soil has no top sandy layer. Differences in corn nutrient concentrations were observed at the V5–V7 stage but not in biomass accumulation. The 12.5 Mg ha−1 target grain yield from applying the low PN was exceeded at both locations (by 19.0%–26.6% in Plains and 6.3%–19.7% in Tifton), irrespective of the SN or MN application. However, the 25.1 Mg ha−1 target grain yield from applying the high PN rate was not achieved, with yields of 16.9–17.7 Mg ha−1 in Plains and 15.7–17.1 Mg ha−1 in Tifton obtained. The SN and/or MN application increased corn yield (by 2.3%–13.6%) across all conditions, but the differences were statistically significant under just the low PN rate in Tifton. Overall, the results showed that SN and MN could be yield‐limiting factors of corn in the Ultisol soils tested in the study, and also 12.5 Mg ha−1 corn yield can be achieved with lower PN rates than currently recommended.

Comprehension of Seismic-Induced Groundwater Level Rise in Unsaturated Sandy Layer Based on Soil–Water–Air Coupled Finite Deformation Analysis

Immense liquefaction damage was observed in the 2011 off the Pacific coast of Tohoku Earthquake. It was reported that, in Chiba Prefecture, Japan, the main shock oozed muddy water from the sandy ground and the aftershock which occurred 29 min after the main shock intensified the water spouting; thus, the aftershock expanded the liquefaction damage in the sandy ground. For comprehending such a phenomenon, using a soil–water–air coupled elastoplastic finite deformation analysis code, a rise in groundwater level induced by main shock is demonstrated, which may increase the potential of liquefaction damage during the aftershock. The authors wish to emphasize that these results cannot be obtained without soil–water–air coupled elastoplastic finite deformation analysis. This is because the rise in groundwater level is caused by the negative dilatancy behavior (plastic volume compression) of the saturated soil layer which supplies water to the upper unsaturated soil layer, and it is necessary to precisely calculate the settlement of ground and the amount of water drainage/absorption to investigate the groundwater level rise. This study provides insight into the mechanism of ground liquefaction during a series of earthquakes.

Seismic behavior of highway embankment reinforced with remedial countermeasures on saturated loose sandy layer

A hybrid pile system is proposed to suppress excessive settlement and lateral spreading, which are regarded as main causes of highway embankment failure due to earthquakes. This system, combining two groups of vertical and inclined piles arranged on both sides of highway embankment slope, can be applied to existing highway embankments. In this research, a series of 1 g shaking table tests were performed together with modeling the performance of highway embankments incorporating three cases with different reinforcements subjected to two sinusoidal waves. Several aspects of acceleration time history, pile deformation, and embankment settlement under three configurations were revealed and discussed to confirm the effectiveness of the proposed countermeasures. The results indicate that (1) the hybrid pile system can still ensure sufficient functionality to maintain the highway embankment after two consecutive strong earthquakes; (2) this system can also enhance the integrity of loose sandy layer to reduce the settlement and lateral spreading of embankment; (3) the inclined piles effectively reduce pile head deformation by increasing the shear strength of the pile.

Thermal Effects on the Soil Water Retention Curves and Hydraulic Properties of Benggang Soil in Southern China

Soil hydraulic properties significantly affect the occurrence and development of collapsing gully walls. The effect of temperature on the hydraulic properties of soil in collapsing gully walls remains unclear. In this study, the hydraulic properties of the red soil layer, the sandy soil layer and the detritus layer in a collapsing gully wall were investigated using the filter paper method, and the soil water retention curves of the different soil layers at 25 and 40 °C were determined. The aim of this study was to investigate the impact of temperature on the soil hydraulic properties of different soil layers in collapsing gully walls. The study found that when the water content in the red soil layer and sandy soil layer exceeded 20% and in the detritus layer exceeded 10%, the soil’s matric suction significantly decreased as the temperature increased from 25 to 40 °C. Additionally, the parameters of θs, α, n and m all exhibited a decreasing trend, and the soil water content in the detritus layer was primarily influenced by the temperature change, which resulted in a decrease of 38.10%. The unsaturated hydraulic conductivity of the detritus layer exhibited higher values than that of the sandy layer and red soil layer under identical temperature conditions. Moreover, the unsaturated hydraulic conductivity of the red soil layer, sandy soil layer and detritus layer increased with increasing temperature. It was observed that the unsaturated hydraulic conductivity of the detritus layer increased by 0.18 cm h−1 at a soil water content of 44%. This increase in conductivity was more pronounced than the corresponding changes in the red soil layer and sandy soil layer. An elevated temperature caused the water-holding capacity of the different soil layers of the collapsing gully wall to decrease and the unsaturated hydraulic conductivity to increase. However, the influence of the clay particle content within the soil of the collapsing gully wall rendered the temperature effect more distinct. Therefore, the destabilizing deformation of the soil in the collapsing gully wall during the summer under high temperatures and precipitation may have played a key role in its collapse.

MINERALOGY AND GEOCHEMISTRY ASSESSMENT OF THE CRETACEOUS SEDIMENTS IN KANADI-1 WELLS, BORNU BASIN FORMATION, NORTH-EASTERN NIGERIA

Mineralogical and Geochemical prospect were used to evaluate the Cretaceous and Tertiary sediments in the Bornu Basin of northeastern Nigeria, particularly those found in Kanadi-1 Wells, seeks to gain insight into their origins and how they were deposited. The Bima Sandstone Formation, the sandy-shale Gongila Formation, and the clayeyshaley Fika Formation, are mainly composed of around 35-58% quartz and up to 50% kaolinitic clay. Notably, the quantity of quartz decreases steadily across the stratigraphic sequence. The base of the Bima Sandstone Formation is characterized by its abundance of arkosic characteristics, consisting of 25% albite feldspars. The sandy layers in the Bornu Basin formation (Bima and Fika) are particularly distinguished by containing 15-25% barite. The SiO2/Al2O3 ratios, ranging from 5 to 6, indicate that the sediments are mostly sandy, while the (NaO +K2O)/(MgO+CaO) ratios of 1 to 2 in the Bima and Gongila Formations show their calcareous nature. Significant increase of barite in both Bima, Gongila, and lower parts of the Fika Formations shows there is presence of 2-3% SO3. These sediments are believed to have originated in environments resembling shallow, tropical conditions. The mineralogical and geochemical features of Cretaceous and Tertiary sediments in the Bornu Basin suggest promising opportunities for exploration. Further research in hydrocarbon, mineral resources, and paleoenvironmental reconstruction can maximize their potential.

Soil plugging of open-ended steel piles during impact driving

During the driving process of an open-ended steel pile, soil is allowed to enter the pile’s core until partial or complete plugging occurs. Once this phenomenon is activated, soil resistance to driving (SRD) increases, which can prevent further soil introduction inside the pile, and in turn halt installation works under similar conditions. In this paper, we demonstrate the relationship between the plugging phenomenon, pile geometry, and driving acceleration by comparing literature with some conducted experiments (Paikowsky, 1990; Magroun, 2012), which show that the risk of plugging decreases mainly with an increase in both pile diameter and driving acceleration. A verification study of plugging occurrence in terms of depth is conducted on an open-ended driven pile at a Moroccan port terminal crossing predominantly sandy layers before anchoring in a lower marl layer. The pile’s bearing capacity is evaluated in both plugged and unplugged cases using the SRD method following the processes of Toolan & Fox (1977) and Alm & Hamre (2001), and based on cone penetration test (CPT) results. The pile is thus found unlikely to plug during driving. As a general rule, we found that the plugging phenomenon must be controlled to avoid any interruption in the pile driving process.

Sheet Pile Failure Caused by Scouring and Sand Mining at Padang River Bank

Ground movement occurred on the banks of the river in Padang which has been protected by steel sheetpile which borders the Factory property. Indications of ground movement are detected through visual observations. It was also reported that the day before the incident there had been continuous rain until the next day. Based on the results of the technical drilling, it appears that the soil density becomes lower after 10m depth. There is a layer of sandy silt with a soft to medium consistency at a depth of about 18m to 26m. With soil conditions that are dominated by sandy soil, the risk of scouring due to river flow is one of the things that needs to be considered. Landslides occur gradually because changes in river flow patterns gradually changed due to internal and external factors. Internal factors are caused by the flow and behavior of the river itself, while external factors are the activity of mining of sand material around the riverbanks. Along with the swift river flow, especially during flood water conditions, the layers of soil material move and are washed away by the flow of water so that there is a gap between the sheetpile and the original soil. These conditions cause the passive resistance of the sheet pile to gradually decrease and to experience deformation due to the pushing of the soil material that has experienced a movement. Important findings in the investigation is that the very soft clay layer underneath the sandy layers was not detected prior to the investigation.