The constant amplitude loading fatigue tests were carried out on the 6061/7075 aluminum alloy TIG fillet welded lap specimens in this study,and the weld seam cross-section hardness was measured.The experimental result...The constant amplitude loading fatigue tests were carried out on the 6061/7075 aluminum alloy TIG fillet welded lap specimens in this study,and the weld seam cross-section hardness was measured.The experimental results show that most specimens mainly failed at the 7075 side weld toes even though the base material tensile strength of 7075 is higher than that of 6061.The maximum stress-strain concentration in the two finite element models is located at the 7075 side weld toe,which is basically consistent with the actual fracture location.The weld zone on the 7075 side experiences severe material softening,with a large gradient.However,the Vickers hardness value on the 6061 side negligibly changes and fluctuates around 70 HV.No obvious defects are found on the fatigue fracture,but a large number of secondary cracks appear.Cracks germinate from the weld toe and propagate in the direction of the plate thickness.Weld reinforcement has a serious impact on fatigue life.Fatigue life will decrease exponentially as the weld reinforcement increases under low stress.It is found that the notch stress method can give a better fatigue life prediction for TIG weldments,and the errors of the predicted results are within the range of two factors,while the prediction accuracy decreases under low stress.The equivalent structural stress method can also be used for fatigue life prediction of TIG weldments,but the errors of prediction results are within the range of three factors,and the accuracy decreases under high stress.展开更多
Treatment of peat soil foundation in Yunnan surrounding Dianchi and Erhai Lakes poses complex problems for engineering projects.It is insufficient to rely on ordinary cement to reinforce peat soil.In order to make the...Treatment of peat soil foundation in Yunnan surrounding Dianchi and Erhai Lakes poses complex problems for engineering projects.It is insufficient to rely on ordinary cement to reinforce peat soil.In order to make the reinforcement reliable,this experiment mixed(ultrafine cement)UFC into ordinary cement to form a composite solidify agent.This study aimed to analyze the influence of UFC proportion on the strength of cement-soil in the peat soil environment.Unconfined compressive strength(UCS)and scanning electron microscope(SEM)tests were conducted on samples soaked for 28 and 90 days,respectively.The test results show that without considering the effects of Humic Acid(HA)and Fulvic Acid(FA),incorporating UFC can significantly improve the UCS of cement-soil.The rapid hydration of the fine particles generates a large number of cementitious products,improves the cohesion of the soil skeleton,and fills the pores.However,when the proportion of UFC increases,the aggregate structure formed by a larger quantity of fine particles reduces the hydration rate and degree of cement hydration,making the UCS growth rate of cement-soil insignificant.In the peat soil environment,HA significantly weakened the UCS of cement-soil in both physical and chemical aspects.However,UFC can mitigate the adverse effect of HA on cement-soil by its small particle size,high surface energy,and solid binding ability.In addition,FA has a positive effect on the UCS of cement-soil soaked for 28 days and 90 days.The UFC addition could promote the enhancement effect of FA on cement-soil UCS.SEM test results showed that cement hydration products increased significantly with the increase of UFC proportion,and cementation between hydration products and soil particles was enhanced.The size and connectivity of cement-soil pores were significantly reduced,thereby improving cement-soil structural integrity.展开更多
The present study investigates the engineering properties of submerged organic silt(orSi)stabilized with F-class fly ash(FA),with and without the addition of an activator(CaO).The utilization of F-class FA for soil im...The present study investigates the engineering properties of submerged organic silt(orSi)stabilized with F-class fly ash(FA),with and without the addition of an activator(CaO).The utilization of F-class FA for soil improvement is an important aspect of sustainable and environmentally-conscious geotechnical engineering when marginal usage of lime and concrete is of great interest to engineers and societies.Currently,discussion is predominantly focused on the positive aspects of using the F-class FA,with a paucity of emphasis on the negative aspects.To explore these features more thoroughly,a series of strength and compressibility tests was conducted.The sample preparation and curing methodology were chosen to replicate the in situ conditions where soil is surcharged and submerged in water.It was found that the incorporation of F-class FA without an activator reduces the undrained shear strength of submerged orSi by about 20%–25%and permanently prevents any thixotropic strength restoration.An increase in undrained shear strength is observed when lime(3%–6%)is added to the soil–FA mixture or when only lime(in the same amount of 3%–6%)is used.Consequently,F-class FA can be successfully used as a filler for slurries with minimum lime content in soil mixing methods.The F-class FA(with or without an activator)shifts the so-called“creep delay”in time,consequently reducing the total creep settlements.The shift of“creep delay”is more considerable for orSi stabilized with lime or with FA and lime as an activator,than for orSi stabilized with pure F-class FA.展开更多
Squeezing phenomena can lead to severe loads in deep tunnels,especially in the presence of a low ratio of surrounding rock strength to overburden pressure.For this reason,it is highly imperative to analyze and identif...Squeezing phenomena can lead to severe loads in deep tunnels,especially in the presence of a low ratio of surrounding rock strength to overburden pressure.For this reason,it is highly imperative to analyze and identify a suitable methodology to estimate the squeezing potential and select a proper support system of rock mass.This study aims to reveal the causes of failure of Tishreen tunnel in the west of Syria and develop remediation measures accordingly so as to bring the tunnel back into service.The tunnel in question was subjected to successive failures such as buckling and spalling of side walls,floor heave,and extremely large convergence reaching the failure state of the tunnel lining.In this study,an effective way was demonstrated to evaluate the squeezing potential of the tunnel lining and appropriate modeling of the long-term response of a tunnel excavated in weak rock.Specifically,the causes of failure of Tishreen tunnel were first evaluated by empirical approaches.Then,a numerical model was developed using a timedependent constitutive model to investigate the time-dependent response of the tunnel lining.On this basis,this study proposed an effective reinforcement schemes including steel ribs,grout injection,ground anchors,and new lining of reinforced concrete.The results show that the Burger viscoplastic model simulates effectively the resulting deformation and creep behavior of squeezing ground.It is also observed that using a combined heavy support system can provide efficient control over squeezing deformation and maintain the serviceability of the tunnel under study.展开更多
Fine debris is an important component of natural debris flows.Previous studies focused primarily on the clay minerals found in the fines,and non-clay minerals were often neglected.The effects of mineralogy of fines on...Fine debris is an important component of natural debris flows.Previous studies focused primarily on the clay minerals found in the fines,and non-clay minerals were often neglected.The effects of mineralogy of fines on debris-mass slurrying and flow behaviors of the resultant slurries are examined herein.The fines(≤0.04 mm)in the<5 mm fraction of the Dongyuege Creek debris-flow deposit is replaced with five other mineral powders with the same maximum particle size.Four types of separate and sequential experiments related to debris slurrying and slurry behaviors are carried out with the prepared clastic materials.The obtained slurrying index ranging from 0.08 to 0.18 shows that non-clay minerals also can function as the fine fractions of debris-flow materials,so long as the requirement of grain size distribution is met.Equidimensional,non-clay minerals making up fines of debris flows can increase the upper solid concentration limits of slurrying(with a maximum of 0.692)and peak values of relative excess water pressure(measured maximum mean peak value is 0.99),leading to higher momentum and higher competence,and thereby more destructive catastrophe.The sediments with platy non-clay mineral-dominated fines have potential for mobilizing into small-to medium-size debris flows with a relatively small competence.Clay minerals in the fines may indeed enhance the liquefaction potential of debris masses by expanding the difference between upper and lower solid concentration limits of slurrying(0.413 and 0.238,respectively,for pure kaolinite),but they significantly suppress the momentum,competence,and destructive power of potential debris flows by lowering upper solid concentration limit of slurrying of debris masses.Alpine catchments rich in non-clay minerals,notably those releasing dolomite into loose sediments,may be more prone to threatening and destructive debris flows.The basin producing clay minerals should be more susceptible to lowmagnitude/high-frequency debris flows with less devastating consequences.展开更多
The study presents the results of over 30,000 numerical analyses on the stability of lava tubes under lunar conditions.The research considered random irregularities in cave geometry and their impact on stability,with ...The study presents the results of over 30,000 numerical analyses on the stability of lava tubes under lunar conditions.The research considered random irregularities in cave geometry and their impact on stability,with a particular focus on the geometric characteristics of identified collapses.We propose a procedure for extracting the collapse areas and integrating it into the stability analysis results.The results were examined to assess the possibility of describing the geometry characteristics of collapses using commonly applied probability density distributions,such as normal or lognormal distribution.Our aim is to facilitate future risk assessment of lunar caves.Such an assessment will be essential prior to robotically exploring caves beneath the lunar surface and can be extended to be used for planetary caves beyond the Moon.Our findings indicate that several collapse characteristics can be represented by unimodal probability density distributions,which could significantly simplify the candidate selection process.Based on our results,we also highlight several key directions for future research and suggested implications related to their future exploration.展开更多
As prestressed concrete(PC)structures age,long-termeffects,e.g.,creep,shrinkage,and prestress losses,compromise their structural performance.Strengthening these aged PC beams has become a crucial matter.One effective ...As prestressed concrete(PC)structures age,long-termeffects,e.g.,creep,shrinkage,and prestress losses,compromise their structural performance.Strengthening these aged PC beams has become a crucial matter.One effective solution is to use externally bonded fiber-reinforced polymer(FRP)sheets;however,limited research has been done on aged PC beams using the FRP,especially for beams with unbonded prestressing strands(UPC beams).Therefore,this research investigates the flexural strengthening efficacy of external FRP sheets on aged UPC beams with unbonded tendons.Aging minimally affected the failure modes of UPC beams,with nonstrengthened beams showing flexural failure via rebar yielding and concrete crushing,and FRP-strengthened beams failing due to FRP debonding and tensile reinforcement yielding,though tendons in the aged beams did not yield due to prestress losses,unlike the new beams.The U-wrap anchor curbed widespread debonding,leading to tensile reinforcement yielding and FRP rupture.Aging hastened crack growth and stiffness loss,increasing deflections and reducing load resistance,but FRP reinforcement mitigated these effects,enhancing cracking resistance by 14%over the unstrengthened aged beams and 7%over the new beams while boosting ultimate resistance by 9%above the non-strengthened new beams.Compared to the new FRP-strengthened beams,the aged counterparts had lower cracking resistance,stiffness and capacity—showing 20%higher deflections,7–9%lower serviceability loads,7%–17%reduced ultimate strength and 17%less deformability—due to prestress losses and premature FRP debonding.展开更多
The effect of using 2%and 10%sodium hydroxide solution as surface treatment of rape straw on its water vapor adsorption properties is analyzed in the relative humidity(RH)range of 0%to 98%.Scanning electron microscopy...The effect of using 2%and 10%sodium hydroxide solution as surface treatment of rape straw on its water vapor adsorption properties is analyzed in the relative humidity(RH)range of 0%to 98%.Scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS),and Fourier-transform infrared spectroscopy(FTIR)are used to investigate the morphological,chemical and structural changes of the treated straw surface.The mineral particles formed on the surface after the treatment are analyzed using X-ray diffraction(XRD).The application of sodium hydroxide solution results in the disruption of the straw surface.As the concentration of sodium hydroxide increases,the disruption of the straw surface increases,and the ability of the straw to adsorb water vapor also increases over the entire RH range.In addition to the surface disruption and chemical changes caused by the alkaline treatment,the differences in the equilibrium moisture content of treated and untreated rape straw can also be attributed to the formation of minerals on the straw surface,namely calcite for the 2%sodium hydroxide solution,and gaylussite and thermonatrite for the 10%solution.展开更多
Exploring alternative aggregates or recycled aggregates to substitute traditional concrete aggregates,particularly sand aggregates,which are becoming more limited and must comply with environmental protection standard...Exploring alternative aggregates or recycled aggregates to substitute traditional concrete aggregates,particularly sand aggregates,which are becoming more limited and must comply with environmental protection standards,is essential.Research has explored various alternative materials to sand in concrete,including concrete from demolished buildings,and broken glass from projects,among others.Investigating the use of recycled broken glass to substitute sand aggregates and implementing this research in compression columns is crucial.This paper examines the compressive behavior of reinforced concrete columns that utilize recycled glass particles as a substitute for sand in concrete.The research findings establish the relationships:load and vertical displacement,load and deformation at the column head,mid-column,and column base;the formation and propagation of cracks in the column,while considering factors such as the percentage of recycled glass,the arrangement of stirrups,and the amount of load-bearing steel influencing the performance of square reinforced concrete columns under compression.The feasibility of using recycled glass as a substitute for sand in column structures subjected to compression has been demonstrated,with the ideal replacement content for sand aggregate in reinforced concrete columns in this study ranging from 0%to 10%.The column’s load-bearing ability dropped from 250 kN to 150 kN when 100%recycled glass was used instead of sand.This is a 40%drop,and cracks started to show up sooner.The research will support recycling broken glass instead of using sand in building,improving the environment and reducing natural sand use.展开更多
The quasi-rectangular tunnel represents a novel cross-section design,intended to supersede the traditional circular and rectangular tunnel formats.Due to the limited capacity of the tunnel vault to withstand vertical ...The quasi-rectangular tunnel represents a novel cross-section design,intended to supersede the traditional circular and rectangular tunnel formats.Due to the limited capacity of the tunnel vault to withstand vertical loads,an interior column is often installed at the center to enhance its load-bearing capacity.This study aims to develop a hyperstatic reaction method(HRM)for the analysis of deformation and structural integrity in this specific tunnel type.The computational model is validated through comparison with the corresponding finite element method(FEM)analysis.Following comprehensive validation,an ensemble machine learning(ML)model is proposed,using numerical benchmark data,to facilitate real-time design and optimization.Subsequently,three widely used ensemble models,i.e.random forest(RF),gradient boosting decision tree(GBDT),and extreme gradient boosting(XGBoost)are compared to identify the most efficient ML model for replacing the HRM model in the design optimization process.The performance metrics,such as the coefficient of determination R2 of about 0.999 and the mean absolute percentage error(MAPE)of about 1%,indicate that XGBoost outperforms the others,exhibiting excellent agreement with the HRM analysis.Additionally,the model demonstrates high computational efficiency,with prediction times measured in seconds.Finally,the HRM-XGBoost model is integrated with the well-known particle swarm optimization(PSO)for the real-time design optimization of quasi-rectangular tunnels,both with and without the interior column.A feature importance assessment is conducted to evaluate the sensitivity of design input features,enabling the selection of the most critical features for the optimization task.展开更多
In soil dynamics,cyclic tests on sands have been extensively studied over the past several decades.Among the natural materials most susceptible to strength loss due to earthquakes,sands are commonly tested under varyi...In soil dynamics,cyclic tests on sands have been extensively studied over the past several decades.Among the natural materials most susceptible to strength loss due to earthquakes,sands are commonly tested under varying loading,frequency,and drainage conditions.Traditionally,it has been assumed that pore pressure increases with constant strength loss once the threshold for pore pressure build-up is reached.However,recent studies have revealed that at small strains,the material initially hardens despite the generation of pore pressure.This paper presents the response and degradation of uniformly graded Drava River sand(DrOS018),similar to well-known sands such as Toyoura,Nevada or Ottawa sands,and the initial hardening phenomena that occur around threshold strains.Tests were conducted using a triaxial cyclic device at three relative densities and cell pressures(100 kPa,200 kPa,and 400 kPa)under undrained conditions.Strain-controlled tests were conducted at 0.1 Hz and 0.05 Hz using sinusoidal loading,with samples prepared by under-compaction.After crossing the threshold,the sand initially shows hardening(degradation index greater than 1)with up to a 35%increase in pore pressure,followed by strength degradation at higher strains.This study is critical for seismic design and safety,particularly for fully saturated sands in coastal and high water table areas.The findings enhance our understanding of liquefaction potential and site response,aiding more informed engineering practices by contributing to enhanced knowledge in soil dynamics and improved predictive models.The results support effective mitigation strategies and infrastructure resilience in earthquake-prone regions such as Croatia.展开更多
Bridge networks are essential components of civil infrastructure,supporting communities by delivering vital services and facilitating economic activities.However,bridges are vulnerable to natural disasters,particularl...Bridge networks are essential components of civil infrastructure,supporting communities by delivering vital services and facilitating economic activities.However,bridges are vulnerable to natural disasters,particularly earthquakes.To develop an effective disaster management strategy,it is critical to identify reliable,robust,and efficient indicators.In this regard,Life-Cycle Cost(LCC)and Resilience(R)serve as key indicators to assist decision-makers in selecting the most effective disaster risk reduction plans.This study proposes an innova-tive LCC-R optimization framework to identify the most optimal retrofit strategies for bridge networks facing hazardous events during their lifespan.The proposed framework employs both single-and multi-objective opti-mization techniques to identify retrofit strategies that maximize the R index while minimizing the LCC for the under-study bridge networks.The considered retrofit strategies include various options such as different mate-rials(steel,CFRP,and GFRP),thicknesses,arrangements,and timing of retrofitting actions.The first step in the proposed framework involves constructing fragility curves by performing a series of nonlinear time-history incre-mental dynamic analyses for each case.In the subsequent step,the seismic resilience surfaces are calculated using the obtained fragility curves and assuming a recovery function.Next,the LCC is evaluated according to the pro-posed formulation for multiple seismic occurrences,which incorporates the effects of complete and incomplete repair actions resulting from previous multiple seismic events.For optimization purposes,the Non-Dominated Sorting Genetic Algorithm II(NSGA-II)evolutionary algorithm efficiently identifies the Pareto front to represent the optimal set of solutions.The study presents the most effective retrofit strategies for an illustrative bridge network,providing a comprehensive discussion and insights into the resulting tactical approaches.The findings underscore that the methodologies employed lead to logical and actionable retrofit strategies,paving the way for enhanced resilience and cost-effectiveness in bridge network management against seismic hazards.展开更多
The paper describes the reasons for imminent failure state of high acoustic barriers,consisting due to slipping and falling of the panels out of the inclined part of the barrier.The reason of threat was the lack of th...The paper describes the reasons for imminent failure state of high acoustic barriers,consisting due to slipping and falling of the panels out of the inclined part of the barrier.The reason of threat was the lack of the overall stability of cantilever columns 8,5 m high and global stability of the structure with a total length of 920 m.Structure and its technical condition were described,conclusions of performed analysis were presented and a way to repair was given.展开更多
When the interface of a multilayered saturated soil is rough with noticeable gaps, heat flow lines converge towards the actual contact points, causing thermal flow contraction. Conversely, in the interface between two...When the interface of a multilayered saturated soil is rough with noticeable gaps, heat flow lines converge towards the actual contact points, causing thermal flow contraction. Conversely, in the interface between two layers of soil with different properties, pore water flows slowly along the pore channels, demonstrating laminar flow phenomenon. To predict the thermal contact resistance and flow contact resistance at the interface, this paper constructs general imperfect thermal contact model and general imperfect flow contact model, respectively. Utilizing a thermo-hydro- mechanical coupling model, the thermal consolidation behavior of multilayered saturated soil under two-dimensional conditions is investigated. Fourier and Laplace transformations are applied to decouple the governing equations, yielding expressions for the temperature increment, pore water pressure, and displacement in multilayered saturated soil. The inverse Fourier-Laplace transformation is then used to obtain numerical solutions, which are compared with degeneration solutions to validate the computational accuracy. The differences in the thermal consolidation process under various thermal contact and flow contact resistance models are discussed. Furthermore, the impact of parameters such as the thermal resistance coefficient, partition thermal contact coefficient, flow contact resistance coefficient, and partition flow contact coefficient on thermal consolidation are investigated. Results indicate that thermal contact resistance creates a relative thermal gradient at the interface, leading to increased pore water pressure and reduced displacement nearby. In contrast, flow contact resistance generates a relative pore pressure gradient at the interface, resulting in increased displacement within the saturated soil with minimal effect on temperature increment distribution.展开更多
The investigation of leachate-contaminated clay(LCC)is essential for landfill engineering assessment and achievement of sustainable development goals.Several static and dynamic laboratory tests,including unconfined co...The investigation of leachate-contaminated clay(LCC)is essential for landfill engineering assessment and achievement of sustainable development goals.Several static and dynamic laboratory tests,including unconfined compressive strength(UCS),California bearing ratio(CBR),and cyclic simple shear,are conducted.Cyclic simple shear experiments on LCCs were performed to evaluate the damping and shear modulus.The investigated factors are vertical load(VL),leachate content(LC),frequency(F),and shear strain(ShS)for LCC.Forensic-based investigation optimization(FBIO)and equilibrium optimizer algorithm(EOA)were utilized in addition to multiple types of ensemble models,including adaptive boosting(ADB),gradient boosting regression tree(GBRT),extreme gradient boosting(XGB) and random forest(RF).The comparison of the methods showed that GBRT-FBIO and XGB-EOA models outperformed other models for shear modulus and damping of LCC.The p-value less than 0.0001 shows the significance of the used models in the response surface methodology(RSM)method.展开更多
Machine learning(ML)models are widely used for predicting undrained shear strength(USS),but interpretability has been a limitation in various studies.Therefore,this study introduced shapley additive explanations(SHAP)...Machine learning(ML)models are widely used for predicting undrained shear strength(USS),but interpretability has been a limitation in various studies.Therefore,this study introduced shapley additive explanations(SHAP)to clarify the contribution of each input feature in USS prediction.Three ML models,artificial neural network(ANN),extreme gradient boosting(XGBoost),and random forest(RF),were employed,with accuracy evaluated using mean squared error,mean absolute error,and coefficient of determination(R^(2)).The RF achieved the highest performance with an R^(2) of 0.82.SHAP analysis identified pre-consolidation stress as a key contributor to USS prediction.SHAP dependence plots reveal that the ANN captures smoother,linear feature-output relationships,while the RF handles complex,non-linear interactions more effectively.This suggests a non-linear relationship between USS and input features,with RF outperforming ANN.These findings highlight SHAP’s role in enhancing interpretability and promoting transparency and reliability in ML predictions for geotechnical applications.展开更多
Ultrahigh-performance concrete(UHPC)is a groundbreaking kind of concrete that distinguishes itself from conventional concrete through its unique material properties.Understanding and managing the time-dependent charac...Ultrahigh-performance concrete(UHPC)is a groundbreaking kind of concrete that distinguishes itself from conventional concrete through its unique material properties.Understanding and managing the time-dependent characteristics of these materials is essential for their effective use in various construction applications.This study presents an experimental evaluation of the compressive and bending properties of the UHPC incorporating polypropylene,steel,and glass fibers.Based on ACI-211 guidelines,the UHPC mix was designed by using three types of aggregates:limestone,andesite,and quartzite,along with 5%fiber content(at varying percentages of 0,5%,10%,15%,and 20%)relative to the cementitious materials,and three different water-to-cement(w/c)ratios(0.24,0.3,and 0.4)were used.In this research,the compressive and flexural strength tests were conducted.The results show that increasing the values of the fibers significantly enhances the compressive strength of the studied samples.Furthermore,the utilization of fibers markedly improves the bending strength of the samples,demonstrating a strong correlation with the yield resistance of the material.Also,findings show that using steel fibers increases the compressive and bending strength of the tested samples more than polypropylene and glass fibers.For instance,in UHPC samples with 0.4 w/c,the average compressive strength values are 82.2 MPa,70.3 MPa,and 67.1 MPa for steel,polypropylene,and glass fibers,respectively.Also,in the flexural strength test,the modulus of rupture is obtained as an average of 6.24 MPa,5.24 MPa and 4.83 MPa for UHPC samples with steel,polypropylene and glass fibers,respectively.展开更多
Soil color changes with water content due to chemical and physical reactions,making it a potential indicator for moisture estimation.By analyzing soil surface images and comparing color variations against laboratory-m...Soil color changes with water content due to chemical and physical reactions,making it a potential indicator for moisture estimation.By analyzing soil surface images and comparing color variations against laboratory-measured water content,a rapid and cost-effective method for moisture determination can be developed.Traditional moisture measurement techniques are time-consuming,so an imaging-based approach would be highly beneficial for quick decision-making.Soil color is also influenced by factors such as particle coarseness,which creates shadows and alters perceived darkness.This research introduces a novel method to isolate true soil color by analyzing the maximum color response in image pixels,minimizing shadow effects.Several equations were derived to correlate color changes with moisture content and were validated against lab measurements to ensure accuracy and simplicity.The most effective equation can be further adapted for satellite imagery by accounting for atmospheric light scattering differences between ground and satellite sensors,enabling large-scale moisture monitoring.The derived equations can be programmed into a software tool,allowing moisture estimation from simple soil surface images.The study involved controlled experiments where soil samples at varying moisture levels were imaged to establish an empirical color-moisture relationship.This method provides a fast,economical,and practical alternative to conventional techniques.However,the approach requires further refinement to account for different soil types globally.Future work should focus on adjusting the model with variables that adapt the color-moisture relationship for diverse soils,ensuring broader applicability.Once optimized,this could significantly improve moisture assessment in agriculture,environmental monitoring,and land management.展开更多
The importance of organic geochemistry and basin modeling is widely recognized and used to understand the source rock potential and hydrocarbon generation history of the Mangahewa Formation,and thereby given the found...The importance of organic geochemistry and basin modeling is widely recognized and used to understand the source rock potential and hydrocarbon generation history of the Mangahewa Formation,and thereby given the foundational role in the petroleum exploration.This study utilized the total organic carbon(TOC)content and hydrogen index(HI)to investigate the dominant kerogen type and hydrogen richness for the significance of petroleum generative potential.The Mangahewa coals and carbonaceous shales exhibit an excellent source rocks,with high total organic content(TOC)of more than 22%.The coals and carbonaceous shales were also characterised by Type Ⅱ‒Ⅲ kerogen with Type Ⅲ kerogen,promising oiland gas-prones.The Mangahewa Formation reached the main oil generation,with vitrinite reflectances between 0.53%and 1.01%.Vitrinite reflectance was also used in developing themal models and reveal the transformation(TR)of 10‒50%kerogen to oil during the Late Miocene.The models also showed that the Mangahewa source rock has a significant oil generation and little expulsion competency,with a TR of up to 54%.These findings support the substantial oil-generating potential in the Taranaki Basin's southern graben and can be used as a guide when developing strategies for an oil exploration program.展开更多
In this paper,Isogeometric analysis(IGA)is effectively integrated with machine learning(ML)to investigate the bearing capacity of strip footings in layered soil profiles,with a focus on a sand-over-clay configuration....In this paper,Isogeometric analysis(IGA)is effectively integrated with machine learning(ML)to investigate the bearing capacity of strip footings in layered soil profiles,with a focus on a sand-over-clay configuration.The study begins with the generation of a comprehensive dataset of 10,000 samples from IGA upper bound(UB)limit analyses,facilitating an in-depth examination of various material and geometric conditions.A hybrid deep neural network,specifically the Whale Optimization Algorithm-Deep Neural Network(WOA-DNN),is then employed to utilize these 10,000 outputs for precise bearing capacity predictions.Notably,the WOA-DNN model outperforms conventional ML techniques,offering a robust and accurate prediction tool.This innovative approach explores a broad range of design parameters,including sand layer depth,load-to-soil unit weight ratio,internal friction angle,cohesion,and footing roughness.A detailed analysis of the dataset reveals the significant influence of these parameters on bearing capacity,providing valuable insights for practical foundation design.This research demonstrates the usefulness of data-driven techniques in optimizing the design of shallow foundations within layered soil profiles,marking a significant stride in geotechnical engineering advancements.展开更多
基金Partially funded by the National Natural Science Foundation of China(No.51065012)。
文摘The constant amplitude loading fatigue tests were carried out on the 6061/7075 aluminum alloy TIG fillet welded lap specimens in this study,and the weld seam cross-section hardness was measured.The experimental results show that most specimens mainly failed at the 7075 side weld toes even though the base material tensile strength of 7075 is higher than that of 6061.The maximum stress-strain concentration in the two finite element models is located at the 7075 side weld toe,which is basically consistent with the actual fracture location.The weld zone on the 7075 side experiences severe material softening,with a large gradient.However,the Vickers hardness value on the 6061 side negligibly changes and fluctuates around 70 HV.No obvious defects are found on the fatigue fracture,but a large number of secondary cracks appear.Cracks germinate from the weld toe and propagate in the direction of the plate thickness.Weld reinforcement has a serious impact on fatigue life.Fatigue life will decrease exponentially as the weld reinforcement increases under low stress.It is found that the notch stress method can give a better fatigue life prediction for TIG weldments,and the errors of the predicted results are within the range of two factors,while the prediction accuracy decreases under low stress.The equivalent structural stress method can also be used for fatigue life prediction of TIG weldments,but the errors of prediction results are within the range of three factors,and the accuracy decreases under high stress.
基金National Natural Science Foundation of China(No.41967035)。
文摘Treatment of peat soil foundation in Yunnan surrounding Dianchi and Erhai Lakes poses complex problems for engineering projects.It is insufficient to rely on ordinary cement to reinforce peat soil.In order to make the reinforcement reliable,this experiment mixed(ultrafine cement)UFC into ordinary cement to form a composite solidify agent.This study aimed to analyze the influence of UFC proportion on the strength of cement-soil in the peat soil environment.Unconfined compressive strength(UCS)and scanning electron microscope(SEM)tests were conducted on samples soaked for 28 and 90 days,respectively.The test results show that without considering the effects of Humic Acid(HA)and Fulvic Acid(FA),incorporating UFC can significantly improve the UCS of cement-soil.The rapid hydration of the fine particles generates a large number of cementitious products,improves the cohesion of the soil skeleton,and fills the pores.However,when the proportion of UFC increases,the aggregate structure formed by a larger quantity of fine particles reduces the hydration rate and degree of cement hydration,making the UCS growth rate of cement-soil insignificant.In the peat soil environment,HA significantly weakened the UCS of cement-soil in both physical and chemical aspects.However,UFC can mitigate the adverse effect of HA on cement-soil by its small particle size,high surface energy,and solid binding ability.In addition,FA has a positive effect on the UCS of cement-soil soaked for 28 days and 90 days.The UFC addition could promote the enhancement effect of FA on cement-soil UCS.SEM test results showed that cement hydration products increased significantly with the increase of UFC proportion,and cementation between hydration products and soil particles was enhanced.The size and connectivity of cement-soil pores were significantly reduced,thereby improving cement-soil structural integrity.
基金supported by the Polish National Science Center(Grant No.2022/06/X/ST10/00320)received by Witold Tisler.
文摘The present study investigates the engineering properties of submerged organic silt(orSi)stabilized with F-class fly ash(FA),with and without the addition of an activator(CaO).The utilization of F-class FA for soil improvement is an important aspect of sustainable and environmentally-conscious geotechnical engineering when marginal usage of lime and concrete is of great interest to engineers and societies.Currently,discussion is predominantly focused on the positive aspects of using the F-class FA,with a paucity of emphasis on the negative aspects.To explore these features more thoroughly,a series of strength and compressibility tests was conducted.The sample preparation and curing methodology were chosen to replicate the in situ conditions where soil is surcharged and submerged in water.It was found that the incorporation of F-class FA without an activator reduces the undrained shear strength of submerged orSi by about 20%–25%and permanently prevents any thixotropic strength restoration.An increase in undrained shear strength is observed when lime(3%–6%)is added to the soil–FA mixture or when only lime(in the same amount of 3%–6%)is used.Consequently,F-class FA can be successfully used as a filler for slurries with minimum lime content in soil mixing methods.The F-class FA(with or without an activator)shifts the so-called“creep delay”in time,consequently reducing the total creep settlements.The shift of“creep delay”is more considerable for orSi stabilized with lime or with FA and lime as an activator,than for orSi stabilized with pure F-class FA.
文摘Squeezing phenomena can lead to severe loads in deep tunnels,especially in the presence of a low ratio of surrounding rock strength to overburden pressure.For this reason,it is highly imperative to analyze and identify a suitable methodology to estimate the squeezing potential and select a proper support system of rock mass.This study aims to reveal the causes of failure of Tishreen tunnel in the west of Syria and develop remediation measures accordingly so as to bring the tunnel back into service.The tunnel in question was subjected to successive failures such as buckling and spalling of side walls,floor heave,and extremely large convergence reaching the failure state of the tunnel lining.In this study,an effective way was demonstrated to evaluate the squeezing potential of the tunnel lining and appropriate modeling of the long-term response of a tunnel excavated in weak rock.Specifically,the causes of failure of Tishreen tunnel were first evaluated by empirical approaches.Then,a numerical model was developed using a timedependent constitutive model to investigate the time-dependent response of the tunnel lining.On this basis,this study proposed an effective reinforcement schemes including steel ribs,grout injection,ground anchors,and new lining of reinforced concrete.The results show that the Burger viscoplastic model simulates effectively the resulting deformation and creep behavior of squeezing ground.It is also observed that using a combined heavy support system can provide efficient control over squeezing deformation and maintain the serviceability of the tunnel under study.
基金supported by the National Natural Science Foundation of China(41931294)the National Natural Science Foundation of China-Yunnan Joint Fund(U1502232,U1033601)。
文摘Fine debris is an important component of natural debris flows.Previous studies focused primarily on the clay minerals found in the fines,and non-clay minerals were often neglected.The effects of mineralogy of fines on debris-mass slurrying and flow behaviors of the resultant slurries are examined herein.The fines(≤0.04 mm)in the<5 mm fraction of the Dongyuege Creek debris-flow deposit is replaced with five other mineral powders with the same maximum particle size.Four types of separate and sequential experiments related to debris slurrying and slurry behaviors are carried out with the prepared clastic materials.The obtained slurrying index ranging from 0.08 to 0.18 shows that non-clay minerals also can function as the fine fractions of debris-flow materials,so long as the requirement of grain size distribution is met.Equidimensional,non-clay minerals making up fines of debris flows can increase the upper solid concentration limits of slurrying(with a maximum of 0.692)and peak values of relative excess water pressure(measured maximum mean peak value is 0.99),leading to higher momentum and higher competence,and thereby more destructive catastrophe.The sediments with platy non-clay mineral-dominated fines have potential for mobilizing into small-to medium-size debris flows with a relatively small competence.Clay minerals in the fines may indeed enhance the liquefaction potential of debris masses by expanding the difference between upper and lower solid concentration limits of slurrying(0.413 and 0.238,respectively,for pure kaolinite),but they significantly suppress the momentum,competence,and destructive power of potential debris flows by lowering upper solid concentration limit of slurrying of debris masses.Alpine catchments rich in non-clay minerals,notably those releasing dolomite into loose sediments,may be more prone to threatening and destructive debris flows.The basin producing clay minerals should be more susceptible to lowmagnitude/high-frequency debris flows with less devastating consequences.
基金The work was performed based on the research project no.2023/51/D/ST10/01956,financed by the National Science Center,Poland.
文摘The study presents the results of over 30,000 numerical analyses on the stability of lava tubes under lunar conditions.The research considered random irregularities in cave geometry and their impact on stability,with a particular focus on the geometric characteristics of identified collapses.We propose a procedure for extracting the collapse areas and integrating it into the stability analysis results.The results were examined to assess the possibility of describing the geometry characteristics of collapses using commonly applied probability density distributions,such as normal or lognormal distribution.Our aim is to facilitate future risk assessment of lunar caves.Such an assessment will be essential prior to robotically exploring caves beneath the lunar surface and can be extended to be used for planetary caves beyond the Moon.Our findings indicate that several collapse characteristics can be represented by unimodal probability density distributions,which could significantly simplify the candidate selection process.Based on our results,we also highlight several key directions for future research and suggested implications related to their future exploration.
基金support by the Ministry of Education and Training of Vietnam for this research,under grant no.B2023-MBS-02.
文摘As prestressed concrete(PC)structures age,long-termeffects,e.g.,creep,shrinkage,and prestress losses,compromise their structural performance.Strengthening these aged PC beams has become a crucial matter.One effective solution is to use externally bonded fiber-reinforced polymer(FRP)sheets;however,limited research has been done on aged PC beams using the FRP,especially for beams with unbonded prestressing strands(UPC beams).Therefore,this research investigates the flexural strengthening efficacy of external FRP sheets on aged UPC beams with unbonded tendons.Aging minimally affected the failure modes of UPC beams,with nonstrengthened beams showing flexural failure via rebar yielding and concrete crushing,and FRP-strengthened beams failing due to FRP debonding and tensile reinforcement yielding,though tendons in the aged beams did not yield due to prestress losses,unlike the new beams.The U-wrap anchor curbed widespread debonding,leading to tensile reinforcement yielding and FRP rupture.Aging hastened crack growth and stiffness loss,increasing deflections and reducing load resistance,but FRP reinforcement mitigated these effects,enhancing cracking resistance by 14%over the unstrengthened aged beams and 7%over the new beams while boosting ultimate resistance by 9%above the non-strengthened new beams.Compared to the new FRP-strengthened beams,the aged counterparts had lower cracking resistance,stiffness and capacity—showing 20%higher deflections,7–9%lower serviceability loads,7%–17%reduced ultimate strength and 17%less deformability—due to prestress losses and premature FRP debonding.
基金supported by the Czech Science Foundation,under project No.20-12166S.
文摘The effect of using 2%and 10%sodium hydroxide solution as surface treatment of rape straw on its water vapor adsorption properties is analyzed in the relative humidity(RH)range of 0%to 98%.Scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS),and Fourier-transform infrared spectroscopy(FTIR)are used to investigate the morphological,chemical and structural changes of the treated straw surface.The mineral particles formed on the surface after the treatment are analyzed using X-ray diffraction(XRD).The application of sodium hydroxide solution results in the disruption of the straw surface.As the concentration of sodium hydroxide increases,the disruption of the straw surface increases,and the ability of the straw to adsorb water vapor also increases over the entire RH range.In addition to the surface disruption and chemical changes caused by the alkaline treatment,the differences in the equilibrium moisture content of treated and untreated rape straw can also be attributed to the formation of minerals on the straw surface,namely calcite for the 2%sodium hydroxide solution,and gaylussite and thermonatrite for the 10%solution.
文摘Exploring alternative aggregates or recycled aggregates to substitute traditional concrete aggregates,particularly sand aggregates,which are becoming more limited and must comply with environmental protection standards,is essential.Research has explored various alternative materials to sand in concrete,including concrete from demolished buildings,and broken glass from projects,among others.Investigating the use of recycled broken glass to substitute sand aggregates and implementing this research in compression columns is crucial.This paper examines the compressive behavior of reinforced concrete columns that utilize recycled glass particles as a substitute for sand in concrete.The research findings establish the relationships:load and vertical displacement,load and deformation at the column head,mid-column,and column base;the formation and propagation of cracks in the column,while considering factors such as the percentage of recycled glass,the arrangement of stirrups,and the amount of load-bearing steel influencing the performance of square reinforced concrete columns under compression.The feasibility of using recycled glass as a substitute for sand in column structures subjected to compression has been demonstrated,with the ideal replacement content for sand aggregate in reinforced concrete columns in this study ranging from 0%to 10%.The column’s load-bearing ability dropped from 250 kN to 150 kN when 100%recycled glass was used instead of sand.This is a 40%drop,and cracks started to show up sooner.The research will support recycling broken glass instead of using sand in building,improving the environment and reducing natural sand use.
基金funded by the Hanoi University of Mining and Geology(Grant No.T23-44)The research is also funded by the German Research Foundation(DFG e Project number 518862444)in collaboration with the Vietnam National Foundation for Science and Technology Development(NAFOSTED)under grant number DFG.105e2022.03The third author was funded by the Postdoctoral Scholarship Program of the Vingroup Innovation Foundation(VINIF)(VINIF.2023.STS.15).
文摘The quasi-rectangular tunnel represents a novel cross-section design,intended to supersede the traditional circular and rectangular tunnel formats.Due to the limited capacity of the tunnel vault to withstand vertical loads,an interior column is often installed at the center to enhance its load-bearing capacity.This study aims to develop a hyperstatic reaction method(HRM)for the analysis of deformation and structural integrity in this specific tunnel type.The computational model is validated through comparison with the corresponding finite element method(FEM)analysis.Following comprehensive validation,an ensemble machine learning(ML)model is proposed,using numerical benchmark data,to facilitate real-time design and optimization.Subsequently,three widely used ensemble models,i.e.random forest(RF),gradient boosting decision tree(GBDT),and extreme gradient boosting(XGBoost)are compared to identify the most efficient ML model for replacing the HRM model in the design optimization process.The performance metrics,such as the coefficient of determination R2 of about 0.999 and the mean absolute percentage error(MAPE)of about 1%,indicate that XGBoost outperforms the others,exhibiting excellent agreement with the HRM analysis.Additionally,the model demonstrates high computational efficiency,with prediction times measured in seconds.Finally,the HRM-XGBoost model is integrated with the well-known particle swarm optimization(PSO)for the real-time design optimization of quasi-rectangular tunnels,both with and without the interior column.A feature importance assessment is conducted to evaluate the sensitivity of design input features,enabling the selection of the most critical features for the optimization task.
基金Project Research Infrastructure for Campus-based Laboratories at the University of Rijeka(RC.2.2.06-0001)funded by the Ministry of Science,EducationSports of the Republic of Croatia.This project has been co-funded by the European Fund for Regional Development(ERDF)The support is gratefully acknowledged.This research was partially supported by the project“Laboratory Research of Static and Cyclic Behavior at Landslide Activation”(uniri-tehnic-18-113)funded by the University of Rijeka,Croatia.
文摘In soil dynamics,cyclic tests on sands have been extensively studied over the past several decades.Among the natural materials most susceptible to strength loss due to earthquakes,sands are commonly tested under varying loading,frequency,and drainage conditions.Traditionally,it has been assumed that pore pressure increases with constant strength loss once the threshold for pore pressure build-up is reached.However,recent studies have revealed that at small strains,the material initially hardens despite the generation of pore pressure.This paper presents the response and degradation of uniformly graded Drava River sand(DrOS018),similar to well-known sands such as Toyoura,Nevada or Ottawa sands,and the initial hardening phenomena that occur around threshold strains.Tests were conducted using a triaxial cyclic device at three relative densities and cell pressures(100 kPa,200 kPa,and 400 kPa)under undrained conditions.Strain-controlled tests were conducted at 0.1 Hz and 0.05 Hz using sinusoidal loading,with samples prepared by under-compaction.After crossing the threshold,the sand initially shows hardening(degradation index greater than 1)with up to a 35%increase in pore pressure,followed by strength degradation at higher strains.This study is critical for seismic design and safety,particularly for fully saturated sands in coastal and high water table areas.The findings enhance our understanding of liquefaction potential and site response,aiding more informed engineering practices by contributing to enhanced knowledge in soil dynamics and improved predictive models.The results support effective mitigation strategies and infrastructure resilience in earthquake-prone regions such as Croatia.
文摘Bridge networks are essential components of civil infrastructure,supporting communities by delivering vital services and facilitating economic activities.However,bridges are vulnerable to natural disasters,particularly earthquakes.To develop an effective disaster management strategy,it is critical to identify reliable,robust,and efficient indicators.In this regard,Life-Cycle Cost(LCC)and Resilience(R)serve as key indicators to assist decision-makers in selecting the most effective disaster risk reduction plans.This study proposes an innova-tive LCC-R optimization framework to identify the most optimal retrofit strategies for bridge networks facing hazardous events during their lifespan.The proposed framework employs both single-and multi-objective opti-mization techniques to identify retrofit strategies that maximize the R index while minimizing the LCC for the under-study bridge networks.The considered retrofit strategies include various options such as different mate-rials(steel,CFRP,and GFRP),thicknesses,arrangements,and timing of retrofitting actions.The first step in the proposed framework involves constructing fragility curves by performing a series of nonlinear time-history incre-mental dynamic analyses for each case.In the subsequent step,the seismic resilience surfaces are calculated using the obtained fragility curves and assuming a recovery function.Next,the LCC is evaluated according to the pro-posed formulation for multiple seismic occurrences,which incorporates the effects of complete and incomplete repair actions resulting from previous multiple seismic events.For optimization purposes,the Non-Dominated Sorting Genetic Algorithm II(NSGA-II)evolutionary algorithm efficiently identifies the Pareto front to represent the optimal set of solutions.The study presents the most effective retrofit strategies for an illustrative bridge network,providing a comprehensive discussion and insights into the resulting tactical approaches.The findings underscore that the methodologies employed lead to logical and actionable retrofit strategies,paving the way for enhanced resilience and cost-effectiveness in bridge network management against seismic hazards.
文摘The paper describes the reasons for imminent failure state of high acoustic barriers,consisting due to slipping and falling of the panels out of the inclined part of the barrier.The reason of threat was the lack of the overall stability of cantilever columns 8,5 m high and global stability of the structure with a total length of 920 m.Structure and its technical condition were described,conclusions of performed analysis were presented and a way to repair was given.
基金Projects(52108347, 52179112, 52178371) supported by the National Natural Science Foundation of ChinaProjects(2020C01147, 2023C01165) supported by the Primary Research and Development Plan of Zhejiang Province,ChinaProject(LQ22E080010) supported by the Outstanding Youth Project of Natural Science Foundation of Zhejiang Province,China。
文摘When the interface of a multilayered saturated soil is rough with noticeable gaps, heat flow lines converge towards the actual contact points, causing thermal flow contraction. Conversely, in the interface between two layers of soil with different properties, pore water flows slowly along the pore channels, demonstrating laminar flow phenomenon. To predict the thermal contact resistance and flow contact resistance at the interface, this paper constructs general imperfect thermal contact model and general imperfect flow contact model, respectively. Utilizing a thermo-hydro- mechanical coupling model, the thermal consolidation behavior of multilayered saturated soil under two-dimensional conditions is investigated. Fourier and Laplace transformations are applied to decouple the governing equations, yielding expressions for the temperature increment, pore water pressure, and displacement in multilayered saturated soil. The inverse Fourier-Laplace transformation is then used to obtain numerical solutions, which are compared with degeneration solutions to validate the computational accuracy. The differences in the thermal consolidation process under various thermal contact and flow contact resistance models are discussed. Furthermore, the impact of parameters such as the thermal resistance coefficient, partition thermal contact coefficient, flow contact resistance coefficient, and partition flow contact coefficient on thermal consolidation are investigated. Results indicate that thermal contact resistance creates a relative thermal gradient at the interface, leading to increased pore water pressure and reduced displacement nearby. In contrast, flow contact resistance generates a relative pore pressure gradient at the interface, resulting in increased displacement within the saturated soil with minimal effect on temperature increment distribution.
文摘The investigation of leachate-contaminated clay(LCC)is essential for landfill engineering assessment and achievement of sustainable development goals.Several static and dynamic laboratory tests,including unconfined compressive strength(UCS),California bearing ratio(CBR),and cyclic simple shear,are conducted.Cyclic simple shear experiments on LCCs were performed to evaluate the damping and shear modulus.The investigated factors are vertical load(VL),leachate content(LC),frequency(F),and shear strain(ShS)for LCC.Forensic-based investigation optimization(FBIO)and equilibrium optimizer algorithm(EOA)were utilized in addition to multiple types of ensemble models,including adaptive boosting(ADB),gradient boosting regression tree(GBRT),extreme gradient boosting(XGB) and random forest(RF).The comparison of the methods showed that GBRT-FBIO and XGB-EOA models outperformed other models for shear modulus and damping of LCC.The p-value less than 0.0001 shows the significance of the used models in the response surface methodology(RSM)method.
基金Ho Chi Minh City University of Technology (HCMUT), VNU-HCM for supporting this study
文摘Machine learning(ML)models are widely used for predicting undrained shear strength(USS),but interpretability has been a limitation in various studies.Therefore,this study introduced shapley additive explanations(SHAP)to clarify the contribution of each input feature in USS prediction.Three ML models,artificial neural network(ANN),extreme gradient boosting(XGBoost),and random forest(RF),were employed,with accuracy evaluated using mean squared error,mean absolute error,and coefficient of determination(R^(2)).The RF achieved the highest performance with an R^(2) of 0.82.SHAP analysis identified pre-consolidation stress as a key contributor to USS prediction.SHAP dependence plots reveal that the ANN captures smoother,linear feature-output relationships,while the RF handles complex,non-linear interactions more effectively.This suggests a non-linear relationship between USS and input features,with RF outperforming ANN.These findings highlight SHAP’s role in enhancing interpretability and promoting transparency and reliability in ML predictions for geotechnical applications.
文摘Ultrahigh-performance concrete(UHPC)is a groundbreaking kind of concrete that distinguishes itself from conventional concrete through its unique material properties.Understanding and managing the time-dependent characteristics of these materials is essential for their effective use in various construction applications.This study presents an experimental evaluation of the compressive and bending properties of the UHPC incorporating polypropylene,steel,and glass fibers.Based on ACI-211 guidelines,the UHPC mix was designed by using three types of aggregates:limestone,andesite,and quartzite,along with 5%fiber content(at varying percentages of 0,5%,10%,15%,and 20%)relative to the cementitious materials,and three different water-to-cement(w/c)ratios(0.24,0.3,and 0.4)were used.In this research,the compressive and flexural strength tests were conducted.The results show that increasing the values of the fibers significantly enhances the compressive strength of the studied samples.Furthermore,the utilization of fibers markedly improves the bending strength of the samples,demonstrating a strong correlation with the yield resistance of the material.Also,findings show that using steel fibers increases the compressive and bending strength of the tested samples more than polypropylene and glass fibers.For instance,in UHPC samples with 0.4 w/c,the average compressive strength values are 82.2 MPa,70.3 MPa,and 67.1 MPa for steel,polypropylene,and glass fibers,respectively.Also,in the flexural strength test,the modulus of rupture is obtained as an average of 6.24 MPa,5.24 MPa and 4.83 MPa for UHPC samples with steel,polypropylene and glass fibers,respectively.
文摘Soil color changes with water content due to chemical and physical reactions,making it a potential indicator for moisture estimation.By analyzing soil surface images and comparing color variations against laboratory-measured water content,a rapid and cost-effective method for moisture determination can be developed.Traditional moisture measurement techniques are time-consuming,so an imaging-based approach would be highly beneficial for quick decision-making.Soil color is also influenced by factors such as particle coarseness,which creates shadows and alters perceived darkness.This research introduces a novel method to isolate true soil color by analyzing the maximum color response in image pixels,minimizing shadow effects.Several equations were derived to correlate color changes with moisture content and were validated against lab measurements to ensure accuracy and simplicity.The most effective equation can be further adapted for satellite imagery by accounting for atmospheric light scattering differences between ground and satellite sensors,enabling large-scale moisture monitoring.The derived equations can be programmed into a software tool,allowing moisture estimation from simple soil surface images.The study involved controlled experiments where soil samples at varying moisture levels were imaged to establish an empirical color-moisture relationship.This method provides a fast,economical,and practical alternative to conventional techniques.However,the approach requires further refinement to account for different soil types globally.Future work should focus on adjusting the model with variables that adapt the color-moisture relationship for diverse soils,ensuring broader applicability.Once optimized,this could significantly improve moisture assessment in agriculture,environmental monitoring,and land management.
基金Supporting Project number(RSP2025R92)at King Saud University,Riyadh,Saudi Arabia,for their support.
文摘The importance of organic geochemistry and basin modeling is widely recognized and used to understand the source rock potential and hydrocarbon generation history of the Mangahewa Formation,and thereby given the foundational role in the petroleum exploration.This study utilized the total organic carbon(TOC)content and hydrogen index(HI)to investigate the dominant kerogen type and hydrogen richness for the significance of petroleum generative potential.The Mangahewa coals and carbonaceous shales exhibit an excellent source rocks,with high total organic content(TOC)of more than 22%.The coals and carbonaceous shales were also characterised by Type Ⅱ‒Ⅲ kerogen with Type Ⅲ kerogen,promising oiland gas-prones.The Mangahewa Formation reached the main oil generation,with vitrinite reflectances between 0.53%and 1.01%.Vitrinite reflectance was also used in developing themal models and reveal the transformation(TR)of 10‒50%kerogen to oil during the Late Miocene.The models also showed that the Mangahewa source rock has a significant oil generation and little expulsion competency,with a TR of up to 54%.These findings support the substantial oil-generating potential in the Taranaki Basin's southern graben and can be used as a guide when developing strategies for an oil exploration program.
文摘In this paper,Isogeometric analysis(IGA)is effectively integrated with machine learning(ML)to investigate the bearing capacity of strip footings in layered soil profiles,with a focus on a sand-over-clay configuration.The study begins with the generation of a comprehensive dataset of 10,000 samples from IGA upper bound(UB)limit analyses,facilitating an in-depth examination of various material and geometric conditions.A hybrid deep neural network,specifically the Whale Optimization Algorithm-Deep Neural Network(WOA-DNN),is then employed to utilize these 10,000 outputs for precise bearing capacity predictions.Notably,the WOA-DNN model outperforms conventional ML techniques,offering a robust and accurate prediction tool.This innovative approach explores a broad range of design parameters,including sand layer depth,load-to-soil unit weight ratio,internal friction angle,cohesion,and footing roughness.A detailed analysis of the dataset reveals the significant influence of these parameters on bearing capacity,providing valuable insights for practical foundation design.This research demonstrates the usefulness of data-driven techniques in optimizing the design of shallow foundations within layered soil profiles,marking a significant stride in geotechnical engineering advancements.
