Farm vehicles approaching weights of sauropods exceed safe mechanical limits for soil functioning

Mechanization has greatly contributed to the success of modern agriculture, with vastly expanded food production capabilities achieved by the higher capacity of farm machinery. However, the increase in capacity has been accompanied by higher vehicle weights that increase risks of subsoil compaction. We show here that while surface contact stresses remained nearly constant over the course of modern mechanization, subsoil stresses have propagated into deeper soil layers and now exceed safe mechanical limits for soil ecological functioning. We developed a global map for delineating subsoil compaction susceptibility based on estimates of mechanization level, mean tractor size, soil texture, and climatic conditions. The alarming trend of chronic subsoil compaction risk over 20% of arable land, with potential loss of productivity, calls for a more stringent design of farm machinery that considers intrinsic subsoil mechanical limits. As the total weight of modern harvesters is now approaching that of the largest animals that walked Earth, the sauropods, a paradox emerges of potential prehistoric subsoil compaction. We hypothesize that unconstrained roaming of sauropods would have had similar adverse effects on land productivity as modern farm vehicles, suggesting that ecological strategies for reducing subsoil compaction, including fixed foraging trails, must have guided these prehistoric giants

A Deep Learning Approach for Predicting Two-dimensional Soil Consolidation Using Physics-Informed Neural Networks (PINN)

Soil consolidation is closely related to seepage, stability, and settlement of geotechnical buildings and foundations, and directly affects the use and safety of superstructures. Nowadays, the unidirectional consolidation theory of soils is widely used in certain conditions and approximate calculations. The multi-directional theory of soil consolidation is more reasonable than the unidirectional theory in practical applications, but it is much more complicated in terms of index determination and solution. To address the above problem, in this paper, we propose a deep learning method using physics-informed neural networks (PINN) to predict the excess pore water pressure of two-dimensional soil consolidation. In the proposed method, (1) a fully connected neural network is constructed, (2) the computational domain, partial differential equation (PDE), and constraints are defined to generate data for model training, and (3) the PDE of two-dimensional soil consolidation and the model of the neural network is connected to reduce the loss of the model. The effectiveness of the proposed method is verified by comparison with the numerical solution of PDE for two-dimensional consolidation. Using this method, the excess pore water pressure could be predicted simply and efficiently. In addition, the method was applied to predict the soil excess pore water pressure in the foundation in a real case at Tianjin port, China. The proposed deep learning approach can be used to investigate the large and complex multi-directional soil consolidation.Comment: 23 page

Effectiveness of Ground Improvement Around Piled-Raft for Tall Wind Turbines in Weak Soil: Analytical and Finite Element Analyses

The generation of sustainable energy from wind has received global recognition in recent years. Large-scale wind farms with tall towers are required to meet the renewable energy demands. Taller towers produce higher power due to steady wind with higher speeds at higher altitudes. The site for building a wind farm is primarily selected based on wind conditions, accessibility to the site, and subsurface conditions. In cases where available land consists of soil with poor geotechnical properties, the construction of foundation can become expensive primarily when the foundation must sustain a substantial horizontal and moment loads induced by a tall wind turbine. In such a circumstance, the soil near the ground surface may be improved to enhance the strength and deformation properties of the soil to achieve substantial economic benefit. The study conducted shows the analytical design, 3D finite element analysis, and cost analysis for a piled-raft foundation for a tall wind turbine on in-situ and improved clays. Initially, the analytical design of the piled-raft foundation for 80 m tall wind turbine on the in-situ soil was completed using the contemporary geotechnical design methods. The final design of the piled-raft foundation in the unimproved ground for design mean wind speed of 80 mph, consisted of 24 auger cast piles each 48.4 m long and 0.457 m in diameter. The raft was designed to be a circular raft, 8 m in diameter and 1 m in thickness. Then, five depths of ground improvement using cement soil mixing (CSM) around the piled-raft foundation were considered, and analytical design was performed for each case. The five successive depths of ground improvement correspond to 0.25, 0.3, 0.35, 0.4, and 0.45 times the diameter of the raft. Two design approaches were used: the first one was to determine the effectiveness of the ground improvement and the second to evaluate the performance. For the first design approach, the length of the piles was adjusted while keeping the number of piles, the diameter of the raft, and the cross-section of pile constant to meet the safety and serviceability requirements. The length of the pile decreased by 79.64 % for the highest depth of ground improvement in comparison with the unimproved case. On the other hand, the differential settlement increased by 73.91 %, and lateral deflection increased by 57.57 % due to the shortening of piles, but these deformations were within the design requirements. For the second approach, the length of the pile was kept constant at 48.4 m, and the deformation behavior of the piled-raft was studied. The differential settlement decreased by 12.9 %, and lateral deflection decreased by 33.05 %. The factor of safety against axial load increased by 104.9 %, and the factor of safety against the moment increased by 126.4 %. To gain further insights into the performance of the piled-raft foundation, three-dimensional finite element models for the piled-raft foundations and supporting soil were created and analyzed using ABAQUS. The FE model created adopting the design outcome from the first approach from analytical design (length of pile varies with ground improvement) lead to a 16.37 % increase in horizontal deflection and 56.67 % increase in differential settlement for the highest level of ground improvement. The FE model created adopting the design outcome from the second approach from analytical design (length of the pile remains constant with ground improvement) leads to a 29.38 % decrease in horizontal deflection and a 1.1 % decrease in the differential settlement. A parametric study was performed by varying the undrained shear strength of soil by ±1standard deviation (σ). The length of the pile increased by 24.38 % with positive variation in undrained shear strength and decreased by 17.36 % with negative variation in undrained shear strength soil. Cost analysis performed by adopting the length of the pile for various cases of ground improvement led to the conclusion that ground improvement reduced the total cost of the foundation

Penetration Forces for Subsurface Regolith Probes

Investigating planetary bodies using penetrometers can provide detailed information about its history and evolution. An estimation of subsurface density and porosity can be made from the shape of the penetration curve. Using penetrometers mounted on planetary platforms could be challenging due to the uncertainty of the subsurface composition and since the maximum allowed force for penetration is the weight of the lander or rover on the surface. Estimation of penetration forces can provide a reliable constraint on the maximum reachable depth without endangering the whole mission. Therefore, knowledge of the required penetration force to specific depths can be helpful in designing the length and shape of the probe. Test probes covering the anticipated diameter (2.5, 1.9, 1.2 and 0.9 cm diameter) and tip angle (30°, 60°, 90°and 120°) were inserted mechanically into regolith analogs. The results showed that tip angle does not have a major effect, while probe diameter and density of the regolith are the most important parameters. Increasing probe diameter from 0.9 to 1.9 cm (i.e. a factor of 2) leads to an increase in penetration force from 200 to 1000 N (i.e. a factor of 5) at 20 cm depth. An increase in bulk density from 1550 to 1700 kg/m3 leads to an increase in penetration force from 10 to 200 N at 20 cm depth. Square probes required less force than circular ones which can allow for easier design of lateral windows

In Situ Soil Property Estimation for Autonomous Earthmoving Using Physics-Infused Neural Networks

A novel, learning-based method for in situ estimation of soil properties using a physics-infused neural network (PINN) is presented. The network is trained to produce estimates of soil cohesion, angle of internal friction, soil-tool friction, soil failure angle, and residual depth of cut which are then passed through an earthmoving model based on the fundamental equation of earthmoving (FEE) to produce an estimated force. The network ingests a short history of kinematic observations along with past control commands and predicts interaction forces accurately with average error of less than 2kN, 13% of the measured force. To validate the approach, an earthmoving simulation of a bladed vehicle is developed using Vortex Studio, enabling comparison of the estimated parameters to pseudo-ground-truth values which is challenging in real-world experiments. The proposed approach is shown to enable accurate estimation of interaction forces and produces meaningful parameter estimates even when the model and the environmental physics deviate substantially.Comment: 10 pages, 6 figures, to be published in proceedings of 16th European-African Regional Conference of the International Society for Terrain-Vehicle Systems (ISTVS

A novel methodological approach for land subsidence prediction through data assimilation techniques

AbstractAnthropogenic land subsidence can be evaluated and predicted by numerical models, which are often built over deterministic analyses. However, uncertainties and approximations are present, as in any other modeling activity of real-world phenomena. This study aims at combining data assimilation techniques with a physically-based numerical model of anthropogenic land subsidence in a novel and comprehensive workflow, to overcome the main limitations concerning the way traditional deterministic analyses use the available measurements. The proposed methodology allows to reduce uncertainties affecting the model, identify the most appropriate rock constitutive behavior and characterize the most significant governing geomechanical parameters. The proposed methodological approach has been applied in a synthetic test case representative of the Upper Adriatic basin, Italy. The integration of data assimilation techniques into geomechanical modeling appears to be a useful and effective tool for a more reliable study of anthropogenic land subsidence

5th Annual Jackson School Research Symposium

Geological Science

Optimization calculation of stope structure parameters based on Mathews stabilization graph method

Mathews stability graphic method, based on the rock classification system, measures the stability of the ore roof area of a relatively simple calculation method and provides a theoretical basis for mine rational design stope structure size parameters. In this study, we used a large-scale tungsten mine in Jiangxi Province as the engineering background and performed on-site engineering geological surveys and indoor ore rock mechanics tests in the middle section of mine 417 to obtain multiple engineering quality indicators for the mines and surrounding rocks. The Mathews stability map method and Barton limit span theory were used. The reasonable size range of the exposed face of the stope was calculated by performing theoretical analysis on the ultimate span. Then, FLAC3D calculation and analysis software were used for the simulation of the stope structure, and the most reasonable design of the exposed surface dimension was selected and used as reference for ensuring the safe production of the mine

Rhizosphere development under alternate wetting and drying in puddled paddy rice

We thank all people who contributed to this work. In particular, Annette Raffan, Luke Harrold, Faraj Elsakloul, Utibe Utin and Yehia Hazzazi for their vivid discussion during and after setting experiment. We would also like to thank Dr. Stewart J Chalmers and Jaime Buckingham for providing technical support. We especially thank Dr. Craig Sturrock, Hounsfield Facility, University of Nottingham for supporting X-ray CT image analysis.Peer reviewe