Many of the world's largest deltas are sinking due to multiple natural and anthropogenic causes. This is particularly evident for the modern Yellow River Delta (YRD) in China, which is one of the ...most dynamic coastal systems on Earth. The YRD has experienced complicated patterns of accretion and erosion as well as significant compaction settlements. However, spatiotemporal variability and the long-term settlement rates law in this complex delta system remain poorly understood. Evidently, the surface settlement is supposedly controlled by a long-term natural compaction process of sediments. We first combined the Small Baseline Subset (SBAS) Interferometric Synthetic Aperture Radar (InSAR) method with a geotechnical model and geological, geomorphological, hydrogeological, and geotechnical data to assess the delta-wide long-term spatiotemporal settlement triggered by the consolidation and compaction of river sediments. The combination of satellite and field observations allows us to gain insights into the primary processes controlling surface movement. A total of seventy-five SAR images acquired by ERS and Envisat from 1992 to 2010 are used to generate three independent interferometric subsets calibrated with leveling to unveil spatiotemporal settlement variability. The densely distributed spatiotemporal measurements enable us to acquire the characteristics of the spatiotemporal variations of land movements. Moreover, the annual average settlement rates are observed within a range of 0 to >30 mm. Results suggest that the relative inland stability of the delta contrasts with the decreasing coastal margin trend at an average annual rate of 15 mm. Moreover, the variability is significantly correlated with the delta evolution and variations in subsoil architecture. A comparative analysis has also been conducted between time series InSAR measurements and the theoretical estimates of settlement derived from the geotechnical model. The strong agreement between the InSAR measurements and the geotechnical modeled results indicates that long-term settlement (in a decade-to-century scale) is primarily driven by the compaction of river sediments. The more the delta sub-lobe was newly formed, the more significant the settlement. Decreasing trends in annual settlement rates from approximately 70 mm to 0 mm in the long-term deposit compaction process are also identified. These findings are useful to understand the YRD morphological evolution and may provide insights into the changes in other deltas worldwide.
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•First multidisciplinary integrated analysis of land deformation in the Yellow River Delta.•Stability of the inland delta contrasts with the sinking trend of the coastal margin.•Long-term deltaic settlement is primarily controlled by sediment compaction.•Variability of settlement rates correlates with estuary delta evolution.•Settlement rate tends to decrease with sediment compaction process.
The rapid development and wide application of the IoT (Internet of Things) has pushed toward the improvement of current practices in greenhouse technology and agriculture in general, through ...automation and informatization. The experimental and accurate determination of soil moisture is a matter of great importance in different scientific fields, such as agronomy, soil physics, geology, hydraulics, and soil mechanics. This paper focuses on the experimental characterization of a commercial low-cost “capacitive” coplanar soil moisture sensor that can be housed in distributed nodes for IoT applications. It is shown that at least for a well-defined type of soil with a constant solid matter to volume ratio, this type of capacitive sensor yields a reliable relationship between output voltage and gravimetric water content.
The use of crushed basic igneous rock and crushed concrete for enhanced rock weathering and to facilitate pedogenic carbonate precipitation provides a promising method of carbon sequestration. ...However, many of the controls on precipitation and subsequent effects on soil properties remain poorly understood. In this study, engineered soil plots, with different ratios of concrete or dolerite combined with sand, have been used to investigate relationships between sequestered inorganic carbon and geotechnical properties, over a two-year period. Cone penetration tests with porewater pressure measurements (CPTu) were conducted to determine changes in tip resistance and pore pressure. C and O isotope analysis was carried out to confirm the pedogenic origin of carbonate minerals. TIC analysis shows greater precipitation of pedogenic carbonate in plots containing concrete than those with dolerite, with the highest sequestration values of plots containing each material being equivalent to 33.7 t C ha−1 yr−1 and 17.5 t C ha−1 yr−1, respectively, calculated from extrapolation of results derived from the TIC analysis. TIC content showed reduction or remained unchanged for the top 0.1 m of soil; at a depth of 0.2 m however, for dolerite plots, a pattern of seasonal accumulation and loss of TIC emerged. CPTu tip resistance measurements showed that the presence of carbonates had no observable effect on penetration resistance, and in the case of porewater pressure measurements, carbonate precipitation does not change the permeability of the substrate, and so does not affect drainage. The results of this study indicate that both the addition of dolerite and concrete serve to enhance CO2 removal in soils, that soil temperature appears to be a control on TIC precipitation, and that mineral carbonation in constructed soils does not lead to reduced drainage or an increased risk of flooding.
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•This study presents results from the first large scale inorganic carbon capture experiment in the world.•Our research shows precipitation of 33.7 and 17.5 t C ha−1 yr−1 for plots containing concrete and dolerite, respectively.•At a depth of 0.2 m for dolerite plots, a pattern of seasonal accumulation and loss of carbonate is observed.•Geotechnical measurements shows that carbonation has no observable impact on penetration resistance.•Soil pore water analysis shows carbonation does not change permeability of the substrate, and hence does not affect drainage.
Subsoil investigations involving geoelectric depth sounding, boring and sampling with in situ and laboratory tests were carried out at an interchange location in a typical basement complex terrain of ...Ilora, Southwestern Nigeria with the objective of detailing the subsurface characteristics and appropriate foundation. The geotechnical investigations utilized 2 Numbers exploratory boreholes while geoelectric depth soundings were carried out at seven (7) points along the traverse using the Schlumberger array. An allowable bearing capacity of 800 kN/m2 was observed for the bedrock revealed at 4.00 and 6.95 m, respectively. The geoelectric depth sounding delineated the bedrock (of resistivity 3000 Ωm) occurring at varying depths of 4.00 to 12.00 m with structural features diagnostic of faulting (resistivity of 1082 / 1282 Ωm) and clayey saprolite of significant thickness (resistivity of 58 / 66 Ωm; thickness of 12 m) localized within about 45 m span. Integration of the data sets indicated that the drilling programme could not decipher the localized features which could be hazardous to the stability of the structure despite the good correlation observed at the points of investigation. This study underlines the need to complement traditional geotechnical testing with geophysical exploration methods for optimal results in subsoil investigation. Keywords: bedrock, foundation failures, geotechnical investigation, saprolite, standard penetration test
•Three different AI techniques was used to investigate maximum deviator stress and axial strain at failure of BF-reinforced silty soils.•The "expert opinion" effect on the membership functions in the ...rule based-FL model was reflected positively in the model performance.•The rule based-FL outperformed the SVM and ANN, with an R2 value of 0.938.
Because the experimental trials in civil engineering field are difficult and time-consuming, the application of artificial intelligence (AI) techniques is attracting considerable attention, with their use enabling successful results to be more easily obtained. In this study, we investigated the effect of fiber size, fiber amount, water content, and cell pressure on maximum deviator stress (MDS) and failure deformation (FD) of basalt fiber (BF)-reinforced, unsaturated silty soils using three AI techniques: the artificial neural network (ANN), support vector machine (SVM), and fuzzy logic (FL). The numerical analyses and experiments were conducted using varying amounts (1, 1.5, and 2%) and lengths (6, 12, and 24 mm) of BF, and a total of 180 samples were prepared for the detailed investigation. In order to compare model performances, R2 and MAPE goodness-of-fit metrics were used. The experimental results revealed that the addition of BF generally increased the MDS of the soils, which corresponds to the shearing resistance. According to AI models result, FL outperformed the SVM and ANN, with a R2 value of 0.938, especially in FD prediction. The sensitivity analysis was performed to ascertain the effect of the inputs on the MDS and FD response variables. Results revealed that fiber length and cell pressure have substantial influence in MDS estimations.
•Established a model for measuring in-situ stress in horizontal boreholes (HF).•Fracture initiation position is observed in the middle section of the wellbore.•Breakdown, reopening and shut-in ...pressures are presented successively in the test.•Formulas for conservative calculation in practical engineering.
Horizontal directional investigation is an alternative method different from traditional (vertical) geotechnical investigation, which can effectively reflect geological conditions along the axis and evaluate the engineering characteristics of tunnels in mountainous areas with super long distances and depths. However, the absence of effective methods to measure in-situ stress in horizontal boreholes hinders the promotion of horizontal directional investigation. This paper relies on the thorough horizontal directional drilling geotechnical investigation of the Tianshan Shengli tunnel in China, based on the method of hydraulic fracturing in-situ stress measurement, the relationship between the direction and magnitude of in-situ stresses and the parameters of the hydraulic fracturing was established in a horizontal borehole by enhancing the previous model of inclined boreholes. The interpretation principles of horizontal boreholes by hydraulic fracturing method are further explored through experimental and numerical study. The conclusion of this paper provides theoretical and empirical support for in-situ stress measurement in horizontal boreholes by hydraulic fracturing method.
Biopolymers are emerging as sustainable and eco-friendly soil stabilizers, but there is a lack of studies investigating their long-term effectiveness. Municipal Solid Waste Fines (MSWF), the portion ...of MSW that passes through a 4.75 mm sieve, were treated with two biopolymers, Xanthan Gum and Agar Gum, and cured at a constant moisture level and room temperature for 7–180 days. Triaxial tests were conducted to determine shear strength parameters at different curing periods and biopolymer concentrations. Results showed that the shear strength of the treated MSWF increased more than 2.5 times when treated with 1.5 % of Xanthan Gum and Agar Gum. The shear strength increased from 85.2 kPa to 307.1 kPa and 322.2 kPa for Xanthan Gum and Agar Gum, respectively. Both biopolymers also improved the angle of internal friction and cohesion of the MSWF with long-term curing. Xanthan Gum exhibited a slower rate of strength gain over a period of up to three months, while Agar Gum-treated MSWF gained the ultimate strength more quickly. Agar Gum showed better strength properties due to its better gel stiffness, and a microstructure study demonstrated that these biopolymers consistently tend to fill pores when used over an extended period. The long-term stability of biopolymer-treated MSWF reflects a green approach, emphasizing the potential for circularity, sustainability, and reduced emissions.
•Study on Xanthan & Agar Gum's impact on stabilizing MSWF.•Treated MSWF shows >2.5x shear strength with 1.5% biopolymer.•Internal friction & cohesion improve with long-term curing.•Biopolymer use promotes circularity, sustainability, & lower emissions.•Aids eco-friendly & cost-effective waste management practices.
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