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This study examined the behavior of silty soil during isotropic consolidation tests in both saturated and unsaturated conditions, as well as suction control of consolidated samples under constant loading. Using experimental data and a numerical method based on unsaturated soil mechanics and one-dimensional consolidation settlement computation, the impact of rising groundwater levels on the settling of a foundation under constant loads was determined. The results indicated that soil settlement is influenced by the soil’s initial compaction and consolidation characteristics, volume change characteristics in infiltration paths, foundation loading dimensions and intensity, initial groundwater depth, and its rising rate. It was found that soil wetting-induced settlement is more affected by the initial groundwater depth and its rising rate than by the foundation loading characteristics. Complete settlement occurs when matric suction equilibrates after soil wetting. In this study, for a square foundation of 10 to 20 m with uniform loading on silty soil, with an initial groundwater level at 25 m rising by 1 to 10 m, the settlement ranged from 5.5 to 49.5 mm.

Predicting surface settlement can identify potential risks associated in shield construction. However, in the construction of under-crossing existing structures, the surface settlement is minimal due to the high stiffness of the existing structure, making it unsuitable as a basis for risk assessment. Therefore, interlayer soil settlement was used as an evaluation index in this paper, which was predicted by the developed multi-parameter time series (MPTS) model. This model establishes new dataset, including time, effective stress ratio (ESR), mechanical fluctuation coefficient (MFC), and interlayer soil settlement, where ESR and MFC take into account the changing geological conditions. This study proposes a novel MPTS model, integrating grid search (GS), nonlinear particle swarm optimization (NPSO), and support vector regression (SVR) algorithms to predict interlayer soil settlement during under-crossing construction. It utilizes GS and NPSO to obtain the optimal hyperparameters for SVR. Sensitivity analysis based on MPTS model was used to identify important parameters and propose specific improvement measures. A real under-crossing tunnel project was adopted to verify the effectiveness of the MPTS. The results show that the new input parameters proposed in this paper reduce mean absolute error (MAE) by 20.3% and mean square error (MSE) by 46.7% of prediction results. Compared with the other three algorithms, GS-NPSO-SVR has better prediction performance. Through Sobol sensitivity analysis, previous settlement, ESR and MFC in fully weathered mudstone and moderately weathered mudstone are identified as the primary parameters affecting the interlayer soil settlement. The improvement measures based on analysis results reduce the accumulated settlement by 79.97%. The developed MPTS model can accurately predict the interlayer soil settlement and provide guidance for water stopping or reinforcement construction.

Aiming at studying the harm caused by sudden ground loadings on existing shield tunnels, a indoor scaled model test with a geometric similarity ratio of 1:15.5 was adopted. Considering the influencing factors such as ground loading, burial depth of the shield tunnel, loading position and soil properties, tunnel convergence deformation, tunnel settlement and deep settlement of soil caused by sudden ground loadings are studied. A three-dimensional finite element simulation is carried out using the Midas software, and deep settlement of soil is calculated by a theoretical method. The purpose of this model test is to further understand the influence of ground surcharges on shield tunnel deformation. The results show that the greater the ground surcharge, the greater the settlement and vertical convergence deformation of the shield tunnel; The further away from the ground surcharge, the smaller the settlement, vertical convergence deformation and lateral convergence deformation of the tunnel. When the pile load size is constant, the greater the burial depth of the tunnel, the smaller the vertical convergence deformation and settlement of the tunnel; the maximum value of deep settlement of the soil always remains at the closest point to the ground surcharge; compared with the use of dry sand, the vertical convergence deformation and settlement of the tunnel are significantly reduced when using wet sand. Both the theoretical calculation results and the numerical simulation results are in good agreement with the indoor model test results.

Shallow foundations are often the most economical option for building support, as they distribute structural weight to soil layers, require minimal earthwork, and do not necessitate specialized machinery. The most common type of soil in the city of Karbala is sandy soil. It is granular and loose by nature which has a relatively low bearing capacity. According to previous studies, the soil weakness is one of the problems with shallow foundation construction. Thus, the aim of this study is to improve the properties of the soil using geogrid reinforcement. Three critical parameters are examined, including depth, size, and number of geogrid layers in the soil reinforcement process to increase bearing capacity and decrease soil settling. The effect of geogrid depth ( ) was studied by considering four depth ratios ( = 0.5, 1.0, 1.5, and 2.0) in order to determine the ideal depth of the geogrid layer, where ( ) refers to the width of the footings. The results indicated that a decrease in depth ratio significantly increased the bearing capacity of footings built on reinforced soil layers compared to those built on natural soil, and the settlement reduction ratio (SRR) also increased. The size of the geogrid layer ( , width of the geogrid layer ( ) was evaluated by evaluating four size ratios ( = 1.5, 3.0, 4.5, and 6.0). With an increasing size ratio of the geogrid layer, the bearing capacity ratio (BRC) was significantly improved. Additionally, the study examined the optimal number of geogrid layers, focusing on single and multiple layers with = 1, 2, 3, and 4. The results showed a higher BRC for footings on reinforced soil layers, as well as a significant rise in SRR with an increase in the number of geogrid layers. Finally, it was concluded that the optimal depth ratio was = 0.5, the size ratio was = 4.5, and reinforced with three geogrid layers, which provided the highest bearing capacity and SRR. The experimental test results were verified by comparing them with those calculated using theoretically developed models. The variation between the experimental and theoretical results is reasonable, confirming that the experimental testing results exhibit a high degree of accuracy.

The construction of superstructures on soft soils demands the desired bearing capacity. This can be achieved through various approaches, including improving soil properties using chemical methods, or by employing techniques such as increasing footing dimensions or using micro piles which are uneconomical and time-consuming. To overcome this, enhancement of bearing capacity of soft soils was done by simple and economical technique i.e., cutting the existing soft soil and filling the Cohesive-frictional soil with a defined ratio of top layer thickness to width of the footing. To conduct this analysis, Plaxis 3D software was employed to investigate soil behaviour and simulate various scenarios, to identify the optimum thickness of the fill layer required to enhance the desired bearing capacity of the strata while ensuring a prescribed settlement and load imposed by the superstructure following the Indian Standards for constructing a multi-storied building. The investigation determined that the optimum top layer thickness to footing width is 2. The findings of this study will contribute valuable insights into geotechnical engineering practices, offering a practical and economical solution for enhancing the bearing capacity of soft soils in construction projects.

Construction issues of high-speed rail infrastructures have been increasingly concerned worldwide, of which the subgrade settlement in soft soil area becomes a particularly critical problem. Due to the high compressibility and low permeability of soft soil, the post-construction settlement of the subgrade is extremely difficult to control in these regions, which seriously threatens the operation safety of high-speed trains. In this work, the significant issues of high-speed railway subgrades in soft soil regions are discussed. The theoretical and experimental studies on foundation treatment methods for ballasted and ballastless tracks are reviewed. The settlement evolution and the settlement control effect of different treatment methods are highlighted. Control technologies of subgrade differential settlement are subsequently briefly presented. Settlement calculation algorithms of foundations reinforced by different treatment methods are discussed in detail. The defects of existing prediction methods and the challenges faced in their practical applications are analyzed. Furthermore, the guidance on future improvement in control theories and technologies of subgrade settlement for high-speed railway lines and the corresponding challenges are provided.

Amazonian Dark Earths (ADEs) are unusually fertile soils characterised by elevated concentrations of microscopic charcoal particles, which confer their distinctive colouration. Frequent occurrences of pre-Columbian artefacts at ADE sites led to their ubiquitous classification as Anthrosols (soils of anthropic origin). However, it remains unclear how indigenous peoples created areas of high fertility in one of the most nutrient-impoverished environments on Earth. Here, we report new data from a well-studied ADE site in the Brazilian Amazon, which compel us to reconsider its anthropic origin. The amounts of phosphorus and calcium—two of the least abundant macronutrients in the region—are orders of magnitude higher in ADE profiles than in the surrounding soil. The elevated levels of phosphorus and calcium, which are often interpreted as evidence of human activity at other sites, correlate spatially with trace elements that indicate exogenous mineral sources rather than in situ deposition. Stable isotope ratios of neodymium, strontium, and radiocarbon activity of microcharcoal particles also indicate exogenous inputs from alluvial deposition of carbon and mineral elements to ADE profiles,  beginning several thousands of years before the earliest evidence of soil management for plant cultivation in the region. Our data suggest that indigenous peoples harnessed natural processes of landscape formation, which led to the unique properties of ADEs, but were not responsible for their genesis. If corroborated elsewhere, this hypothesis would transform our understanding of human influence in Amazonia, opening new frontiers for the sustainable use of tropical landscapes going forward. Amazonian Dark Earth is soil that has had mysteriously high fertility since ancient times, despite the fact that surrounding soils have very low nutrients. Here the authors’ use of isotope reconstructions indicate that these soils predate human settlement and could have alluvial and burning origins.

Aims In West Africa, savannas are changing to either forest islands or arable lands arising from anthropogenic interference with the natural ecosystem. This study aimed at quantifying the trade-offs of this land use conversion on major soil quality indicators. Methods We evaluated soil organic matter (SOM) and other soil quality indicators such as macro- and micronutrients (including the absence of some hazardous trace metals) using standard methodologies across 11 settlements in Burkina Faso, Ghana, and Nigeria. The degree of soil quality improvement/degradation and soil quality were assessed using empirical models. Results The effects of savanna conversion were manifold and varied depending on the type of land use change, soil depth, and soil quality indicator. In savanna-forests, there was a substantial rise in SOM (37%—794%) and exchangeable cations (15% to 800%) and changes in SOM in the topsoil quadrupled that of the subsoil. A general loss in SOM (1% -74%) and soil macro-and micronutrients occurred under savanna-arable lands. Potassium, calcium and magnesium increased by ≥ 12%, ≥ 15% and 27% respectively while increases in Mn and Zn were 37% and ≥ 250% in the forests over the savannas. Trace quantities of Pb were detected which were below the contamination threshold. About 63% forest islands, 18% arable land, and 9% savannas had SQI % ≥ 50. Conclusion In marginal lands, land use conversion to forest islands presents great potential for improving soil fertility and overall ecosystem health as shown in the high organic matter and improved soil quality.

Nowadays, different methods are used to study historical masonry buildings. Among these, for the study of architectures with complex geometry, the effectiveness of an integrated approach, that is a method of analysis combining different disciplines, is increasingly evident.The aim of this paper is to show the importance of combining direct observation with structural analysis in order to understand the level of safety in buildings with composite geometries.This paper describes the analysis executed in the XX century parish church of San Bernardino in Sesto Calende (Va), which displays serious cracks and damage caused by soil settlements.The integrated approach starts with historical analysis, by consulting all available documents and drawings. To understand the geometry of the structure a new survey has been made and a three-dimensional digital representation was modeled, by which better deriving the weight of all the elements in the construction, and to find the correct actions and thrust on arches, columns, bases and foundation. All this data was used in the structural analysis based on the static method of limit analysis. For the material behavior the model proposed by J. Heyman (1966) is used, considering the “no tension” failure criterion. The static theorem of minimum reactions for settled states enunciated by M. Como (2010) is employed for the analysis of soil settlement effects on the building’s response.The work shows how direct survey of geometry and damage of a complex building has an effective importance in the structural analysis to ensure Cultural Heritage preservation and safety.

In regions where the soil conditions exhibit softness, engineering endeavours frequently encounter obstacles such as significant settlement and restricted load-bearing capability of shallow foundations. In order to address these challenges and to have the safety of infrastructure, it is vital to utilize techniques for improving the ground. The emergence of polymer materials has paved the way for the progression of technology for Geosynthetic Reinforced Soil (GRS) foundation treatment, which is extensively applied in the construction of highways, railways, and buildings. Geosynthetic reinforced soil (GRS) involves the incorporation of geosynthetic materials, often reinforced with polymers, into the soil to enhance its mechanical and engineering properties. This reinforcement serves to improve the distribution of loads, reduce settlement, and ultimately amplify the overall bearing capacity.