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Keywords = static triaxial test

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22 pages, 8871 KiB  
Article
Performance of Monotonic Pile Penetration in Sand: Model Test and DEM Simulation
by Jianxue Feng, Ruiqi Luo, Xiaoyu Dong, Xiaoyong Zhang and Quan Shen
Buildings 2024, 14(10), 3327; https://doi.org/10.3390/buildings14103327 - 21 Oct 2024
Viewed by 678
Abstract
By integrating laboratory tests and three-dimensional discrete element methods, this research extensively explores the macroscopic and microscopic mechanisms of static pile penetration in standard sand. Initially, the mesoscopic parameters of standard sand were established via flexible triaxial compression tests, and a three-dimensional discrete [...] Read more.
By integrating laboratory tests and three-dimensional discrete element methods, this research extensively explores the macroscopic and microscopic mechanisms of static pile penetration in standard sand. Initially, the mesoscopic parameters of standard sand were established via flexible triaxial compression tests, and a three-dimensional discrete element model was created using the particle size magnification technique. The study results confirm the rationality of parameter selection and numerical modeling by comparing penetration resistance and displacement obtained from laboratory model tests and discrete element simulations. Initially, penetration resistance swiftly increases, then stabilizes progressively with increasing depth. The lateral friction resistance grows with penetration depth, especially peaking near the cone tip. Moreover, horizontal stress quickly rises during pile penetration, mainly caused by the pile foundation compressing the adjacent soil particles. Displacement of the foundation particles is primarily focused around the pile side and cone tip, affecting an area roughly twice the pile diameter. Soil particle displacement exhibits a pronounced vertical downward movement, primarily driven by lateral friction. The distribution of force chains among foundation particles indicates that the primary stressed areas are at the pile ends, highlighting stress concentration features. This research offers significant insights into the mechanical behaviors and soil responses during pile foundation penetration. Full article
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18 pages, 26928 KiB  
Article
Seismic Prediction Method of Shale Reservoir Brittleness Index Based on the BP Neural Network for Improving Shale Gas Extraction Efficiency
by Xuejuan Zhang, Haiyan She, Lei Zhang, Ruolin Li, Jiayang Feng, Ruhao Liu and Xinrui Wang
Energies 2024, 17(18), 4751; https://doi.org/10.3390/en17184751 - 23 Sep 2024
Viewed by 668
Abstract
The current seismic prediction methods of the shale brittleness index are all based on the pre-stack seismic inversion of elastic parameters, and the elastic parameters are transformed by Rickman and other simple linear mathematical relationship formulas. In order to address the low accuracy [...] Read more.
The current seismic prediction methods of the shale brittleness index are all based on the pre-stack seismic inversion of elastic parameters, and the elastic parameters are transformed by Rickman and other simple linear mathematical relationship formulas. In order to address the low accuracy of the seismic prediction results for the brittleness index, this study proposes a method for predicting the brittleness index of shale reservoirs based on an error backpropagation neural network (BP neural network). The continuous static rock elastic parameters were calculated by fitting the triaxial test data with well logging data, and the static elastic parameters with good correlation with the brittleness index of shale minerals were selected as the sample data of the BP neural network model. A dataset of 1970 data points, characterized by Young’s modulus, Poisson’s ratio, shear modulus, and the mineral brittleness index, was constructed. A total of 367 sets of data points from well Z4 were randomly retained as model validation data, and 1603 sets of data points from the other three wells were divided into model training data and test data at a ratio of 7:3. The calculation accuracy of the model with different numbers of nodes was analyzed and the key parameters of the BP neural network structure such as the number of input layers, the number of output layers, the number of hidden layers, and the number of neurons were determined. The gradient descent method was used to determine the weight and bias of the model parameters with the smallest error, the BP neural network model was trained, and the stability of the brittleness index prediction model of the BP neural network was verified by posterior data. After obtaining Young’s modulus, Poisson’s ratio, and shear modulus through pre-stack seismic inversion, the BP neural network model established in this study was used to predict the brittleness index distribution of the target layer in the study area. Compared with the conventional Rickman method, the prediction coincidence rate is 69.16%, and the prediction coincidence rate between the prediction results and the real value is 95.79%, which is 26.63% higher. The BP neural network method proposed in this paper provides a reliable new method for seismic prediction of the shale reservoir brittleness index, which has important practical significance for clarifying the shale gas development scheme and improving shale gas exploitation efficiency. Full article
(This article belongs to the Section H: Geo-Energy)
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12 pages, 2668 KiB  
Article
Experimental Study on Static and Dynamic Characteristics of Sand–Clay Mixtures with Different Mass Ratios
by Ye Cheng and Jinghu Yang
Sustainability 2024, 16(17), 7343; https://doi.org/10.3390/su16177343 - 26 Aug 2024
Viewed by 766
Abstract
The alteration of soil static and dynamic characteristics induced by clay content constitutes a crucial issue in the realm of disaster prevention and mitigation within geotechnical engineering. The static and dynamic characteristics of mixed soils with varying sand–clay contents were investigated through the [...] Read more.
The alteration of soil static and dynamic characteristics induced by clay content constitutes a crucial issue in the realm of disaster prevention and mitigation within geotechnical engineering. The static and dynamic characteristics of mixed soils with varying sand–clay contents were investigated through the design and implementation of static and dynamic triaxial tests. The relationship between clay content and soil resistance to liquefaction was investigated, with an analysis of the influence of clay content on soil strength and static liquefaction performance. Furthermore, the study examined the soil’s resistance to liquefaction under dynamic constitutive and cyclic loading conditions for soils with varying clay content. Results indicate that stress–strain curves for samples with varying clay content exhibit a consistent trend, with the lowest tangent modulus and peak strength observed in samples containing 30% clay. Increasing clay content diminishes soil’s resistance to liquefaction under static loading conditions. Higher confining pressures correspond to larger tangent moduli and peak deviating stresses in triaxial shear tests. Dynamic shear modulus decreases as clay content increases, whereas damping ratio decreases accordingly. Soil gradation significantly affects liquefaction-induced deformation, with the sample containing 30% clay experiencing the fastest increase in pore water pressure during testing failure, accompanied by fewer cyclic loading cycles until failure occurs. Improving soil gradation and adjusting the sand–clay ratio are beneficial for enhancing both soil strength and its resistance to liquefaction. Full article
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23 pages, 9521 KiB  
Article
Effect of Plastic Fine Content on the Static Liquefaction Potential of Sandy Soil
by Quang-Huy Dang, Philippe Reiffsteck, Minh-Ngoc Vu, Tuan Nguyen-Sy and Van-Hung Pham
Appl. Sci. 2024, 14(13), 5881; https://doi.org/10.3390/app14135881 - 5 Jul 2024
Viewed by 847
Abstract
This study aims to investigate the effect of plastic fine content on the undrained monotonic behavior of sandy soils (mixtures of host sand and various plastic fine content from 0 to 25%), and in particular, their static liquefaction resistance (undrained shear strength). Illite [...] Read more.
This study aims to investigate the effect of plastic fine content on the undrained monotonic behavior of sandy soils (mixtures of host sand and various plastic fine content from 0 to 25%), and in particular, their static liquefaction resistance (undrained shear strength). Illite Arvel is considered as a plastic fine to add to the host sand, the Fontainebleau sand. Binary mixture samples are reconstituted by using the moist tamping technique. A series of undrained triaxial tests were carried out to study the influence of different parameters, such as the fine content, the initial density index, the confining pressure, and the over-consolidation ratio (OCR) on the behavior of sandy soil mixture. Based on the results acquired from these tests, the liquefaction susceptibility of the sandy soil is discussed by using Chinese criteria. Full article
(This article belongs to the Section Civil Engineering)
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15 pages, 6840 KiB  
Article
Dynamic Binary-Medium Model for Jointed Rock Subjected to Cyclic Loading
by Mingxing Liu, Enlong Liu, Xingyan Liu and Qingsong Zheng
Mathematics 2024, 12(11), 1765; https://doi.org/10.3390/math12111765 - 6 Jun 2024
Viewed by 687
Abstract
Revealing the damage mechanism of jointed rocks under a cyclic loading and formulating the corresponding dynamic constitutive model to meet the requirements for the evaluation of anti-vibration safety for critical engineering construction and operation is an essential, urgent and basic subject. Based on [...] Read more.
Revealing the damage mechanism of jointed rocks under a cyclic loading and formulating the corresponding dynamic constitutive model to meet the requirements for the evaluation of anti-vibration safety for critical engineering construction and operation is an essential, urgent and basic subject. Based on the breakage mechanics for geological material, jointed rock is considered as a binary-medium material composed of the bonded elements and frictional elements. The bonded elements are regarded as elastic-brittle elements, and the frictional elements are regarded as elastic-plastic elements. Firstly, the static binary-medium model for jointed rock is established based on the homogenization method and by introducing the breakage ratio and the strain concentration coefficient. Then, the dynamic binary-medium model for jointed rock under cyclic loads is established considering the nonlinear damage effect resulting from cyclic loads. The breakage ratio formula is improved, and the Drucker–Prager criterion is introduced. During the unloading stage, it is supposed that the breakage ratios and strain concentration coefficients remain unchanged and the stress–strain ratios of both bonded elements and frictional elements are constant. The model is verified by static and dynamic triaxial tests of jointed rock samples with an interpenetrated joint. It is found that the model can describe the nonlinear stress–strain characteristics of a jointed rock subjected to cyclic loads relatively well and can reflect the effects of cyclic loading on the deformation and damage, including the lateral deformation characteristics. Meanwhile, the typical three-stage (varying from sparse to dense to sparse) evolution laws of the stress–strain curves are also reflected relatively well. Full article
(This article belongs to the Special Issue Numerical Modeling and Simulation in Geomechanics)
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22 pages, 6072 KiB  
Article
Triaxial Load Cell for Ergonomic Risk Assessment: A Study Case of Applied Force of Thumb
by Mario Acosta-Flores, Martha Roselia Contreras-Valenzuela, J. Guadalupe Velásquez-Aguilar, Francisco Cuenca-Jiménez and Marta Lilia Eraña-Díaz
Appl. Sci. 2024, 14(10), 3981; https://doi.org/10.3390/app14103981 - 8 May 2024
Viewed by 1033
Abstract
To assess the ergonomic risk level in work systems involving tasks performed with hands or fingers, it is necessary to know the exerted triaxial forces. To address this need, a prototype of a triaxial load cell based on principles of linear elasticity theory [...] Read more.
To assess the ergonomic risk level in work systems involving tasks performed with hands or fingers, it is necessary to know the exerted triaxial forces. To address this need, a prototype of a triaxial load cell based on principles of linear elasticity theory and mechanical problems of torsion, bending and axial load is presented. This work includes an analytical strain model for each instrumented point and its solution regarding the applied force to a triaxial load cell. The proposed load cell was calibrated and validated by performing different static experimental tests. As a case study, the applied force in three directions while the thumb activates a cigarette lighter was measured. Triaxial forces and resultant forces were obtained and compared with the parameter of 10 N established by the ergonomic standards as reference values for pressing down with the thumb, finding that the applied forces in eight tests were 23.73 N, 43.51 N, 12.69 N, 14.50 N 20.35 N, 21.67 N, 39.74 N and 46.02 N, exceeding the reference values and establishing a direct relationship with Quervain syndrome. In conclusion, the developed load cell is a valid and reliable alternative to measure many forces that cannot be obtained with commercial devices, allowing the level of ergonomic risk to be determined with great precision. Full article
(This article belongs to the Special Issue Advanced Sensing Technology for Structural Health Monitoring)
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14 pages, 5665 KiB  
Article
Investigations on the Johnson-Cook Constitutive and Damage-Fracture Model Parameters of a Q345C Steel
by Fengquan Hu, Xin Liu, Boshi Wang and Yong Xiang
Metals 2024, 14(5), 509; https://doi.org/10.3390/met14050509 - 26 Apr 2024
Cited by 3 | Viewed by 2324
Abstract
Due to the rapid development of high-speed trains, the service safety of vehicle body materials and structures has become a focal point in transport and impact engineering. Numerical simulations on the collision resistance of vehicle materials and structures are crucial for the safety [...] Read more.
Due to the rapid development of high-speed trains, the service safety of vehicle body materials and structures has become a focal point in transport and impact engineering. Numerical simulations on the collision resistance of vehicle materials and structures are crucial for the safety assessment and optimal structural design of high-speed trains but have not been fully investigated due to the lack of damage model parameters. This study focuses on the Johnson-Cook (J-C) constitutive and damage-fracture models of a typical vehicle material, Q345C steel. A series of mechanical tests are conducted on the Q345C steel, including the quasi-static and dynamic compression/tension tests, quasi-static tension tests at different temperatures, and fracture tests along different stress paths, using the material test system and the split Hopkinson pressure/tension bar. Then, the parameters of the Johnson-Cook constitutive and damage-fracture models are calibrated based on the experimental results. In terms of the damage parameters related to stress paths, a new method of combining experiments and simulations is proposed to obtain the real, local fracture strains of the Q345C steel samples. This method allows the measurements of equivalent plastic strain and stress triaxiality histories under nonlinear stress paths, which are hardly accessible from individual experiments, and facilitates the accurate calibration of stress-path-related damage parameters. In addition, a high-speed plate penetration test is used to validate the J-C parameters, which can be directly implemented in the commercial finite element software Abaqus. The projectile trajectories from the simulation and experiment agree well with each other, demonstrating the reliability of the model parameters for impact scenarios and the efficiency of the experimental procedures utilized for calibration. Full article
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20 pages, 11541 KiB  
Article
The Beneficial Effect of a TPMS-Based Fillet Shape on the Mechanical Strength of Metal Cubic Lattice Structures
by Christian Iandiorio, Gianmarco Mattei, Emanuele Marotta, Girolamo Costanza, Maria Elisa Tata and Pietro Salvini
Materials 2024, 17(7), 1553; https://doi.org/10.3390/ma17071553 - 28 Mar 2024
Cited by 5 | Viewed by 1233
Abstract
The goal of this paper is to improve the mechanical strength-to-weight ratios of metal cubic lattice structures using unit cells with fillet shapes inspired by triply periodic minimal surfaces (TPMS). The lattice structures here presented were fabricated from AA6082 aluminum alloy using lost-PLA [...] Read more.
The goal of this paper is to improve the mechanical strength-to-weight ratios of metal cubic lattice structures using unit cells with fillet shapes inspired by triply periodic minimal surfaces (TPMS). The lattice structures here presented were fabricated from AA6082 aluminum alloy using lost-PLA processing. Static and dynamic flat and wedge compression tests were conducted on samples with varying fillet shapes and fill factors. Finite element method simulations followed the static tests to compare numerical predictions with experimental outcomes, revealing a good agreement. The TPSM-type fillet shape induces a triaxial stress state that significantly improves the mechanical strength-to-weight ratio compared to fillet radius-free lattices, which was also confirmed by analytical considerations. Dynamic tests exhibited high resistance to flat impacts, while wedge impacts, involving a high concentrated-load, brought out an increased sensitivity to strain rates with a short plastic deformation followed by abrupt fragmentation, indicating a shift towards brittle behavior. Full article
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17 pages, 5713 KiB  
Article
A Sustainable Option to Reuse Scaly Clays as Geomaterial for Earthworks
by Marco Rosone and Clara Celauro
Geosciences 2024, 14(1), 17; https://doi.org/10.3390/geosciences14010017 - 5 Jan 2024
Cited by 1 | Viewed by 1911
Abstract
Scaly clays are structurally complex clay formations found throughout the world. Their typical fissured structure, the low shear strength and the high swelling potential often make them unsuitable for earthworks in road and railway infrastructure. This research has attempted to extend the possibilities [...] Read more.
Scaly clays are structurally complex clay formations found throughout the world. Their typical fissured structure, the low shear strength and the high swelling potential often make them unsuitable for earthworks in road and railway infrastructure. This research has attempted to extend the possibilities of using this geomaterial in this field after appropriate lime treatment. A laboratory test programme was carried out to evaluate the response of the treated geomaterial to typical loads acting on road infrastructures. Unconfined and confined compression tests as well as cyclic triaxial tests, in undrained conditions, were carried out to investigate the static and dynamic mechanical behaviour. The results show that lime treatment induces significant improvements in the geomechanical properties and limits the swelling behaviour upon saturation of the geomaterial. Dynamic tests showed that, after only 28 days of curing, the treated scaly clay became insensitive to the damaging cyclic loading caused by vehicular traffic. The collected results show that the scaly clay can be properly used as a subgrade and embankment layer in road and railway construction with limited economic and environmental costs, after accurate treatment with lime. These results are significant for researchers and practitioners to increase sustainability in the construction of linear infrastructures involving excavations in scaly clays and to avoid landfill, which in some cases represented the only option. Full article
(This article belongs to the Section Geomechanics)
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28 pages, 37795 KiB  
Article
Dynamic Evaluation of Sealing and Site Optimization for Underground Gas Storage in Depleted Gas Reserve: A Case Study
by Xianglong Zhuge, Jiajun Hong, Cong Wang, Jianping Wang and Huifen Xia
Appl. Sci. 2024, 14(1), 298; https://doi.org/10.3390/app14010298 - 29 Dec 2023
Cited by 1 | Viewed by 1315
Abstract
In the post-epidemic economic recovery background, under the influence of the international situation brought by the Russia-Ukraine conflict, the world is facing a significant rebound in total energy consumption. In order to seek a smooth transition for national energy low-carbon transformation, it is [...] Read more.
In the post-epidemic economic recovery background, under the influence of the international situation brought by the Russia-Ukraine conflict, the world is facing a significant rebound in total energy consumption. In order to seek a smooth transition for national energy low-carbon transformation, it is urgent that research be conducted on the trap dynamic sealing capacity evaluation and site optimization for underground storage in depleted gas reserves. Based on the geological data of Block S in Northeast China, combined with a dynamic acoustic test and a static triaxial test, a rock mechanical property model for wells is established, and the stress model of the underground storage in depleted gas reserves before construction is inverted. The sealing of the cap rock and faults in the underground gas storage is evaluated from both static and dynamic perspectives. The results show that the maximum horizontal principal stress of the cap rock and reservoir before construction is distributed between 48–76 MPa and 50–85 MPa, respectively. The reservoir of the Yingcheng Formation has strong stratigraphic mechanical strength and can be used as the main space for underground gas storage. The global cap rock shear safety factor is between 0.7–0.9, and the fault slip factor is only 0.1, indicating that this reservoir has strong dynamic closure sealing and is suitable for construction, thereby realizing the dynamic evaluation of sealing and site optimization for underground gas storage in a depleted gas reserve, providing a guarantee for the safe and stable operation of its subsequent expansion, multi-cycle injection, and production. Full article
(This article belongs to the Special Issue Underground Energy Storage in Mining and Tunneling Engineering)
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16 pages, 3447 KiB  
Article
Experimental Study of the Dynamic Characteristics of PVA-Amended Expansive Soils
by Xinshan Zhuang, Bowen Zhang, Xiaofei Li, Duan Yang and Wu Wen
Appl. Sci. 2024, 14(1), 292; https://doi.org/10.3390/app14010292 - 28 Dec 2023
Viewed by 929
Abstract
Expansive soils are distributed across a wide area in China, and land transport and surface construction will inevitably involve these soils. To mitigate the deficiencies of single-method expansive soil modification, it is highly important to adopt the use of polyvinyl alcohol (PVA) to [...] Read more.
Expansive soils are distributed across a wide area in China, and land transport and surface construction will inevitably involve these soils. To mitigate the deficiencies of single-method expansive soil modification, it is highly important to adopt the use of polyvinyl alcohol (PVA) to improve expansive soils and enhance the strength and toughness of modified soils. In addition, solidification technology can be utilized for the resource utilization of expansive soils. In this study, triaxial testing is employed to evaluate the mechanical properties of solidified soil. When the confining pressure is the same and with increasing PVA content, soil particles and PVA combine to form a cemented substance, which fills the internal pores of the soil samples, enhances the cohesion between soil particles, and improves the bearing capacity of the soil. The stress–strain curve for the modified soil first increases and then decreases. The shear strength peaks at a PVA content of 3%. Based on the improved soil with a 3% PVA content, GDS dynamic triaxial tests were carried out to investigate the effects of different confining pressures and frequencies on the dynamic stress–strain curves, dynamic modulus of elasticity, and variation rule for the damping ratio of the improved soil. The results show that the dynamic stress–strain curve for the improved soil increases with increasing confining pressure and frequency and that the dynamic stress–strain backbone curves exhibit significant nonlinearities at different frequencies and circumferential pressures. The dynamic elastic modulus increases with increasing confining pressure and frequency and decreases gradually with increasing dynamic strain. The initial dynamic modulus of elasticity increases with increasing envelope pressure and frequency but is less affected by frequency, and the damping ratio decreases with increasing confining pressure and frequency. Soil treatment can improve the pore distribution, inhibit the extension of soil cracks, and enhance soil compactness. Full article
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15 pages, 4318 KiB  
Article
Characterization and Simulation of Shear-Induced Damage in Selective-Laser-Sintered Polyamide 12
by Daniela Schob, Lukas Richter, Krzysztof Kotecki, Dariusz Kurpisz, Robert Roszak, Philipp Maasch and Matthias Ziegenhorn
Materials 2024, 17(1), 38; https://doi.org/10.3390/ma17010038 - 21 Dec 2023
Viewed by 1035
Abstract
This paper presents the characterisation of selective-laser-sintered (SLS) samples of polyamide 12 (PA12) under shear loading. PA12 is a semi-crystalline thermoplastic and is used in various industries. Its behaviour under shear stress, which is particularly important for product reliability, has not yet been [...] Read more.
This paper presents the characterisation of selective-laser-sintered (SLS) samples of polyamide 12 (PA12) under shear loading. PA12 is a semi-crystalline thermoplastic and is used in various industries. Its behaviour under shear stress, which is particularly important for product reliability, has not yet been sufficiently investigated. This research focuses on understanding the material and damage behaviour of PA12 under shear-induced stress conditions. The study included quasi-static experiments and numerical simulations. Samples were prepared via SLS and tested according to ASTM standards. Digital image correlation (DIC) was used for precise deformation measurements. The Chaboche material model was used for the viscoplastic behaviour in the numerical simulations. Due to existing material discontinuities in the form of voids, the material model was coupled with the Gurson–Tvergaard–Needleman (GTN) damage model. A modified approach of the GTN model was used to account for low stress triaxiality under shear loading. These models were implemented in MATLAB and integrated into Abaqus via a User Material (UMAT) subroutine. The results of the experiments and simulations showed a high degree of accuracy. An important finding was the significant influence of the shear factor kw on the damage behaviour, especially during failure. This factor proved to be essential for the accurate prediction of material behaviour under shear-induced stress conditions. The integration of the modified GTN model with the Chaboche material model in UMAT enables an accurate prediction of the material and damage behaviour and thus makes an important contribution to the understanding of the mechanical material behaviour of SLS PA12 specimens. Full article
(This article belongs to the Special Issue Computational Modeling and Simulation of Polymers and Biopolymers)
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19 pages, 8134 KiB  
Article
Strength Assessment of Water–Glass Sand Mixtures
by Toshiyuki Motohashi, Shigeo Sasahara and Shinya Inazumi
Gels 2023, 9(11), 850; https://doi.org/10.3390/gels9110850 - 27 Oct 2023
Cited by 1 | Viewed by 2288
Abstract
For years, the chemical injection process has aided construction works by increasing the strength and water-sealing efficiency of sandy soil. Despite its growing popularity in projects, such as seismic strengthening and liquefaction mitigation, a unified understanding of how chemically treated soil develops its [...] Read more.
For years, the chemical injection process has aided construction works by increasing the strength and water-sealing efficiency of sandy soil. Despite its growing popularity in projects, such as seismic strengthening and liquefaction mitigation, a unified understanding of how chemically treated soil develops its strength, especially under static conditions, remains elusive. Some studies have proposed that strength is derived from the tensile effects of dilatancy, where shearing of the sandy soil causes expansion, creating tension in the interstitial hydrogel and resulting in negative pressure that consolidates the soil particles. Other studies, however, attribute this strength development to the volumetric shrinkage of the hydrogel, which the authors argue confines and compresses the sandy soil particles. Challenges are encountered with this theory, particularly with respect to the consistency of the volumetric shrinkage measurements and the timing of these measurements in relation to changes in soil strength. The aim of the current research is to shed light on this mechanism by using consolidation drainage triaxial compression (CD) tests to measure the cohesive strength and internal friction angle of chemically enhanced soil. By eliminating the dilatancy-induced negative pressure effects and coupling this with an analysis of the molecular structure of the hydrogel, the present study provides an in-depth look at the strength development mechanism and its durability. This holistic approach not only fills in the existing gaps in the understanding of this mechanism, but also paves the way for optimized construction techniques. Full article
(This article belongs to the Section Gel Chemistry and Physics)
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15 pages, 3123 KiB  
Article
Research on the Accumulated Pore Pressure of Expansive Soil under Subway Loading
by Lin Qing, Lei Zhu, Ying Guo and Gan Cheng
Buildings 2023, 13(10), 2596; https://doi.org/10.3390/buildings13102596 - 14 Oct 2023
Viewed by 1029
Abstract
Taking the expansive soil near Hefei Xinqiao International Airport as the research subject, indoor dynamic triaxial tests were conducted to investigate the influence of different loading methods on the dynamic pore pressure of saturated remolded expansive soil on the basis of maximally simulating [...] Read more.
Taking the expansive soil near Hefei Xinqiao International Airport as the research subject, indoor dynamic triaxial tests were conducted to investigate the influence of different loading methods on the dynamic pore pressure of saturated remolded expansive soil on the basis of maximally simulating the real characteristics of subway loading. Furthermore, the action laws of three factors, namely intermittent loading ratio, static deviator stress, and cyclic stress ratio, on the accumulated pore pressure of saturated remolded expansive soil under intermittent subway cyclic loading were analyzed. The research results indicate that the loading method significantly affects the development trend of the accumulated pore pressure. Under similar conditions, a larger intermittent loading ratio leads to smaller accumulated pore pressure values and a slower initial development rate of pore pressure under the same cycle vibration. Increasing static deviatoric stress promotes the accumulation of pore pressure. The influence of the cyclic stress ratio is dependent on the intermittent loading ratio and does not follow a consistent pattern. Full article
(This article belongs to the Special Issue Problematic Soils in Building Construction)
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9 pages, 1775 KiB  
Communication
Active Reduction of Apparent Cable Capacitance
by Alexander Melin, Michael Roberts and Roger Kisner
Sensors 2023, 23(19), 8319; https://doi.org/10.3390/s23198319 - 8 Oct 2023
Viewed by 1693
Abstract
This paper presents a method for reducing apparent cable capacitance seen by sensors. The proposed method is designed for sensing in extreme environments including ultra-high temperatures, but can be applied in benign environments as well. By reducing the cable capacitance, high speed signals [...] Read more.
This paper presents a method for reducing apparent cable capacitance seen by sensors. The proposed method is designed for sensing in extreme environments including ultra-high temperatures, but can be applied in benign environments as well. By reducing the cable capacitance, high speed signals can be transmitted over longer distances, allowing the application of advanced control systems that require high bandwidth data for stable operation. A triaxial cable with an associated guard circuit is developed that actively reduces cable capacitance while also rejecting extraneous electric and magnetic interference on the signal. The active capacitance reduction method developed is tested experimentally and shown to reduce apparent cable capacitance to two percent of the static value. Full article
(This article belongs to the Section Industrial Sensors)
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