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The coefficient of consolidation (Cv) of soft soil is a parameter that reflects the consolidation characteristics of soil under load, but it usually costs a lot in time and money to test. In this paper, an artificial neural network (ANN) and a support vector machine (SVM) are used to establish the Cv prediction model, and the soft soil data of Guigang Beihai Expressway in Guangxi are used to train and test the model. Eleven physical and mechanical parameters of soft soil are statistically analyzed by correlation matrix. Four parameters are determined as input parameters of the calculation model to train and test the calculation model, and the performance and robustness of the prediction model are checked. The results show that the ANN model and SVM model both accurately calculate the Cv, with coefficient of correlation R2 > 0.91, root mean square error RMSE < 0.2079 cm2/1000s, and variance ratio VAF > 90%. The prediction accuracy of the ANN model is better than that of the SVM model, and the Monte Carlo simulation results show that the SVM model is most robust. Therefore, the consolidation coefficient is connected with other physical and mechanical parameters, and the ANN model and SVM model are used to predict the Cv, which provides a new idea for fast calculation of the Cv. [ABSTRACT FROM AUTHOR]

Soil thermal conductivity (λ) is an important parameter in thermal calculation and temperature-field analysis in geotechnical engineering. To accurately predict it, this paper uses individual and ensemble machine learning methods to establish predictive models. The λ measurements were obtained (n = 337) and saturation, dry density, quartz content, sand content and clay content were selected as input parameters for the predictive models. The performance of the prediction model is evaluated by Inspection parameters. The predictive model was k-fold cross-validated and compared with traditional empirical models. The results show that individual and ensemble machine learning models accurately predict λ. The random forest model had the best predictive accuracy, with a correlation coefficient R2 = 0.979, root mean square error (RMSE) = 0.097 Wm−1 K−1 and mean absolute error (MAE) = 0.07 Wm−1 K−1. The MLR model had the worst predictive accuracy. The accuracy of ensemble machine learning models was obviously better than those of individual machine learning models. The accuracy of the proposed predictive model was significantly higher than that of the traditional empirical model. According to the results of performance tests and k-fold cross-validation, the RF and decision tree + bagging models are recommended for predicting λ. [ABSTRACT FROM AUTHOR]

The site investigation is a key part of the design of tunnel construction projects, as it provides accurate geotechnical parameters. A systematic site investigation, which consists of mainly in situ tests and laboratory sample tests, was conducted for the Haimen-Taicang river-crossing tunnel project on Yangtze River. This paper aims to analyze and compare the piezocone penetration testing (CPTU) and dilatometer test (DMT) results of both onshore and under-river subsoils to provide insights into the interpretation of the in-situ tests. The accuracy of well-documented interpretation methods based on CPTU and DMT was discussed. Current empirical correlations between in-situ test results and unit weight, undrained shear strength and constrained modulus of the subsoils were checked, and their site adaptability was discussed in detail. A series of site-specific correlations were derived based on the analysis of the in-situ tests and the comparison between the in situ tests interpretation and the laboratory results. In order to reduce the errors between testing locations caused by soil variability and get the consistent understanding of soil behaviors, CPTU–DMT correlations were reviewed and improved based on local testing results. [ABSTRACT FROM AUTHOR]

To enhance the adsorption performance of municipal sludge biochar on Cd(II), modified sludge biochar was prepared by sodium hydroxide/magnesium chloride (NaOH/MgCl2) graded activation, and the Cd(II) adsorption performance on sludge biochar (BC), NaOH-activated sludge biochar (NBC) and NaOH/MgCl2 activated sludge biochar (NBC-Mg) was investigated. The results showed that NaOH/MgCl2 graded activation upgraded the surface structure and enhanced the graphitization of sludge biochar. The adsorption experiments indicated that the adsorption kinetic and adsorption isotherm for Cd(II) were in accordance with the pseudo second-order kinetic and Langmuir model. The adsorption capacity of NBC-Mg (143.49 mg/g) for Cd(II) was higher than that of BC (50.40 mg/g) and NBC (85.20 mg/g). The mechanism of Cd(II) adsorption included ion exchange, complexation, cation-π interaction, and mineral precipitation. After five regeneration, the removal efficiency of Cd(II) by NBC-Mg remained above 90%. This work indicated that sludge biochar prepared by multistage activation could be an effective material for Cd-containing wastewater treatment. [ABSTRACT FROM AUTHOR]

In recent decades, research on real-time monitoring and early warning of subgrades under the action of dynamic stress fields in geotechnical engineering has been gaining increasing attention. However, current internal deformation monitoring of subgrades is based primarily on point monitoring, which lacks distributed measurement capabilities. In this regard, in this study, a sensor-enabled piezoelectric geocable (SPGC) based on the piezoelectric effect and impedance–strain effect is used to conduct cyclic shear tests at the SPGC–sand interface. The monitoring effect is evaluated by obtaining the stress–strain–voltage–impedance information during the test. The test results show that the strain measurement range of SPGC can reach more than 9%. In most instances, with an increase in the normal stress σn, displacement amplitude Aw, and shear frequency f, the normalized impedance kZ drop of the SPGC increases, as well as the peak voltage URMS and effective voltage Upeak. The shape of the stress hysteresis loop under cyclic shearing can be accurately determined using normalized impedance and voltage. The normalized impedance and voltage responses of the SPGC under different dynamic stress conditions exhibit high sensitivity and discrimination. This indicates that the SPGC has the potential to be applied as a distributed accelerometer or geophone, which plays an important role in acquiring geoacoustic information while monitoring the internal shear deformation of the subgrade. Finally, a long-term data processing method for the normalized impedance and voltage of the SPGC is proposed. The research results help realize the disaster location and precursor identification of the subgrade. [ABSTRACT FROM AUTHOR]

The residual friction angle ( ∅ r ′ ) is an important indicator used to evaluate the stability of soil slopes, and most of its correlation studies are based on one or more parameters such as the plasticity index, clay fraction, and normal stress. Existing methods for residual friction angle prediction involving plastic limit measurements have the drawbacks of complicated procedures and excessive errors. In this paper, the flow index is used instead of the plasticity index, the plasticity index of fine-grained soil based on the flow index (FI) is proposed, and the correlation of the residual friction angle is studied. The results indicate that (1) both the flow index and plasticity index can reflect the plasticity capacity of fine-grained soil, but the flow index is simple to obtain and more accurate. (2) Flow index, flow clay factor, flow plasticity angle, and the vertical distance of A-Line (Δ FI) can characterize the residual shear properties of fine-grained soils, which generally show that the residual friction angle gradually decreases with increasing plasticity. (3) To address the problem of scattered or excessive data in the existing calculation models, an improved model for calculating the residual friction angle is proposed based on the clay fraction and flow index, and its fitting results are significantly better than those of the existing calculation models. (4) The correlation between residual friction angle and flow index is suitable for predicting the accuracy of residual shear test results, but has limitations when used to predict the residual friction angle. [ABSTRACT FROM AUTHOR]

Site amplification models were developed as part of the Next Generation Attenuation (NGA) project to evaluate potential seismic risks in areas of North America. However, these models have low validity in seismic risk prediction in deep soft soil deposits (DSSDs) due to the lack of sufficient seismic recordings collected from DSSDs and site-specific dynamic parameters of local soils. Soil profiles from Suzhou City, China were used to validate the NGA nonlinear site amplification model (referred to as WSA08) and establish a simpler one based on 1-D site response results with high-frequency dominated (HFD) input motions. Fully nonlinear (NL) method which can capture the nonlinear behavior of soft soils was used to establish the simple functional form of nonlinear amplification model. Compared with WSA08, an accommodation coefficient A was added to adjust the ordinate of the Amps, while the linear amplification component was removed due to the epistemic uncertainty of linear amplification in DSSDs. The practicality of the simple model was validated using another three HFD input motions at different periods. [ABSTRACT FROM AUTHOR]

Scrap tire rubber is light mass and has heat-insulation properties. It can be mixed with building materials to form a new type of sustainable composite. Thermal conductivity is an important parameter affecting the thermal properties of building materials. Herein, the thermal conductivity of scrap rubber–sand mixtures was measured using a thermal probe; the effects of rubber content, moisture content, and dry density on the thermal conductivity of the mixture were studied, and a theoretical calculation model for the thermal conductivity of scrap rubber–sand mixtures was established. The results show that the thermal conductivity of scrap rubber–sand mixtures decreases with increases in the rubber content and reductions in the dry density. The thermal conductivity of the mixture increases with increases in moisture content. The established theoretical calculation model can accurately calculate the thermal conductivity of scrap rubber–sand mixtures, with R2 = 0.88, MAE = 0.044 (Wm−1 K−1), and RMSE = 0.071 (Wm−1 K−1). The prediction accuracy of the theoretical model is obviously superior to that of the traditional empirical model. It provides an accurate method for predicting the thermal conductivity of scrap rubber–sand mixtures. [ABSTRACT FROM AUTHOR]

Microstructure, texture and mechanical property of Fe-27Mn-3Si-4Al TWIP steels during asymmetric warm rolling were studied. It was found that asymmetric warm rolling strongly refined the microstructures and affected texture evolution of steels because of an additional shear strain in contrast to the symmetric warm rolling. The complete recrystallization occurred on the upper and central layer of sheet, and Goss and Brass textures was developed into γ-fiber and R-Copper {112} <110> textures when the velocity ratio increased to 1.2. The combination of applied asymmetry rolling at elevated reduction resulted in a high yield strength (706 MPa) due to the enhanced shear deformation on the one hand and a reasonably high elongation (26.3%) on the other hand which was attributable to the grain fragmentation at higher velocity ratio, while the significant enhancement of ductility (30.9%) was achieved by the higher dislocation activation due to the decrease of rolling reduction. [ABSTRACT FROM AUTHOR]

Urban sludge is an extensive volume with a prominent environmental impact. The research explored an application technology for converting urban sludge into a usable improved soil resource by using industrial waste, providing a new reference for the reuse of industrial waste. In this study, three industrial wastes, namely ground granulated blast slag, calcium carbide residue, and desulfurized gypsum, were used as curing agents to solidify the urban sludge. Based on the unconfined compressive strength (UCS) test and chamber analysis, the effects of curing agent dosing and maintenance age of sludge-cured soil on the UCS and stress- strain were studied. The results showed that with the increase of curing agent, the UCS of cured soil first increased and then decreased, and the breaking strain showed a decreasing trend. The optimum ratio of materials was sludge: calcium carbide residue: ground granulated blast slag: desulfurization gypsum = 100:15:15:5, record this material ratio as C15G15D5. Moreover, trials showed that C15G15D5 cured the sludge soil better than the cement alone, which achieved the purpose of reusing the three industrial wastes and urban sludge. It was analyzed that the hydrated calcium silicate (C-S-H), calcium aluminate (C-A-H) and ettringite (AFt) in the hydration products were produced to make the soil skeleton stronger and enhance the strength of the sludge-cured soil. [ABSTRACT FROM AUTHOR]

Shear wave velocity (Vs) offers engineers a promising alternative means to evaluate liquefaction resistance of sandy soils. However, the Vs-based probabilistic evaluation of soil liquefaction using machine learning method or Bayesian network method is limited. To this end, an attractive probability framework incorporating grey wolf optimization optimized kernel extreme learning machine (GWO–KLEM), and Bayesian theorem was developed for Vs-based probabilistic liquefaction model. The framework mainly includes two components: (1) an GWO–KLEM-based metamodel is developed to approximate the limit state function and identify the uncertain location of the boundary between the liquefaction and the non-liquefaction points; (2) the Bayesian theorem along with total probability theorem is used to integrate the prior knowledge with the site-specific Vs data for the updated distributions of input parameters. Then, a large number of equivalent samples from the above integrated knowledge can be generated based on the Markov chain Monte Carlo simulation; thus the probability of liquefaction can be calculated. Based on searching technique, perspective under simplified framework is also developed. The results show that limit state function searched by GWO–KELM is reliable and the proposed Vs-based probabilistic liquefaction model has a very good performance. Details on the development of the proposed system are presented, along with comparisons of the results obtained by this system with existing methods. Overall, the proposed method is advantageous and reliable for probabilistic assessment of liquefaction potential. [ABSTRACT FROM AUTHOR]

The high water content and viscosity make construction mud extremely difficult to manage, causing land occupation and environmental pollution problems. This research aims to investigate the durability of ground granulated blast furnace slag (S) and calcium carbide residue (CCR), two industrial by-products, solidified waste mud under wetting–drying cycles, and assess its serviceability as subgrade material. The tests of unconfined compressive strength (UCS), mass loss, and scanning electron microscope (SEM) were carried out to analyze mechanical and microstructural characterization of solidified mud. The optimal binder content and S:CCR ratio in terms of UCS values were found at 25% and 8:2, respectively. The maximum compressive strength at 7 days reached 3.73 MPa. There was a logarithm function between the development of compressive strength and curing time. The hydration reaction still occurred during the wetting–drying cycles; thus, UCS value first fluctuated and then gradually decreased with the progression of wetting–drying cycles. SEM images showed that the effect of the wetting–drying cycles on the solidified mud was manifested by the increase of pore and the decrease of hydration products. It was found that S-CCR is an environmentally friendly binder for bored pile mud solidification, which facilitates the reduction of a large number of waste by-products and waste mud from landfills. [ABSTRACT FROM AUTHOR]

Piles are often installed before tunnel excavation to support the tunnel structure. However, excavation inevitably causes disturbance to the soil below the excavation surface, significantly changing the soil mechanical behavior. Hence, it is necessary to evaluate the excavation effects on pile load-settlement behavior. This study proposes a semi-analytical approach for estimating the load-settlement behavior of a pile beneath the excavation surface, that considers the excavation effects. Piezocone tests are performed in the Taihu tunnel region to evaluate the excavation effects on the soil mechanical properties. The results show that after excavation, the undrained shear strength of the soil decreases, while the soil effective friction angle remains unchanged. Thus, this study proposes using the soil effective friction angle before excavation to predict the pile load-settlement behavior after excavation. Then, the load-transfer method is employed to simulate the pile settlement behavior. Hyperbolic functions are used to describe the nonlinear loading and unloading pile-soil interface behavior. The proposed semi-analytical approach also considers the shear-induced elastic deformation of the surrounding soil. The predictions of the load-settlement behavior are compared to the results of pile load tests in the Taihu tunnel region, centrifuge model tests, and numerical investigations to validate this approach. The excellent agreement indicates that the proposed approach can reasonably predict the pile load-settlement behavior after excavation. As a case study, it is predicted that the ultimate capacity of a pile in the Taihu tunnel region is 4388 kN, reflecting a 10% loss of pile capacity due to excavation. [ABSTRACT FROM AUTHOR]

The solidification/stabilization effect of heavy metal contaminated soils in frozen soil regions may be weakened. A novel binder comprising calcium carbide residue, metakaolin, and desulfurization gypsum was used to solidify and stabilize copper-contaminated soil subjected to freeze-thaw (F-T) cycles. The unconfined compressive strength (UCS), F-T cycles, scanning electron microscope (SEM), X-ray diffraction (XRD), and pH tests were conducted to investigate the characteristics of UCS, deformation, pH value, and microscopic mechanism of contaminated soils. The results demonstrated that the UCS of contaminated soils decreased with the increasing F-T cycles and Cu2+ concentration; the strength loss rate increased first and then decreased as the F-T cycles increased. The failure strain rose first and then reduced with the increase of F-T cycles, and increased with the rise of Cu2+ concentration. There was a considerable correlation between UCS, failure strain, and deformation modulus E50. The pH value decreased with the increasing F-T cycles and Cu2+ concentration. The microscopic characteristics indicated that the formation of hydrated calcium silicate and ettringite was the fundamental reason for the enhanced UCS. Besides, heavy metals could be solidified and stabilized by chemical precipitation, physical encapsulation, and ion exchange. The effect of F-T cycles could significantly damage the internal structure of contaminated soils, and the frost heaving force could loosen the soil skeleton structure, leading to the deterioration of the mechanical properties. [ABSTRACT FROM AUTHOR]

Soft clay generally cannot be directly used as subgrade material due to its poor engineering characteristics. The application of rice husk ash (RHA) for the solidification of problematic soil contributes to the recycling of waste and reduces carbon emissions. A series of mechanical, chemical, and microscopic tests were conducted to assess the early effectiveness of RHA in stabilizing soft clay. The pH and conductivity Ec also were measured to evaluate the effect of active ions. The results show that the use of RHA alone can only improve the compressive strength qu of soft clay to a certain extent. However, it cannot improve the soaked strength of the solidified soil. Carbide slag (CS) and metakaolin (MK) as activators were used to modify RHA, which significantly improved the compressive strength, shear properties, and soaked strength of soft clay. During initial curing, the compressive strength qu and cohesion c showed a marked correlation with pH and Ec. This is closely related to the dissolution and consumption behaviors of more abundant active ions contributed by the active oxides in the modified RHA. Finally, combined with XRD, SEM, EDS, and MIP tests indicated that the mechanical properties and microstructure improvement of soft clay can be attributed to the early physical reinforcement and meshing effect due to the porous granular structure of RHA. Subsequently generated CaCO3 crystals and C–S–H/C–A–S–H cementitious hydrates played a crucial role through carbonization and pozzolanic reactions supported by more abundant active ions. [ABSTRACT FROM AUTHOR]

We have already carried out the research on the pyrolysis kinetics and pyrolysis process mechanism of waste circuit board resin powder. In this study, we focused on the physical and chemical properties of solid–gas–liquid phase products from the pyrolysis of resin powder. The pyrolysis process of WPCB at different heating rates was analyzed by thermogravimetric analyzer (TG), and the parameters were statistically analyzed. Scanning electron microscopy was employed to observe the micro-morphology of the pyrolytic solid products under the high-resolution demonstration conditions of 5 μm and 1 μm, mainly the combination morphology of pyrolytic carbon and glass fiber, and the combination energy spectrum analysis was used to detect the elements C, Si, Al and Ca as the main chemical components of the solid substances. In order to further understand the composition and distribution of functional groups in the pyrolysis residues, the absorption vibration peaks of pyrolysis carbon were determined by Fourier transform infrared spectroscopy (FTIR), and the attribution of different vibration peaks was interpreted. It was found that the key chemical substances were the substitutes of phenol, isopropyl phenol and bisphenol A. The chemical structure types and yield of liquid pyrolysis tar at pyrolysis temperature of 673.15 K were tested by gas chromatography–mass spectrometry (GC–MS). The major constituent of liquid-phase product was phenolic compounds, the total content of which is 74.63%. The composition of non-condensable gasses produced by WPCB under vacuum pyrolysis conditions was observed by GC–MS, mainly containing H2, CO2, CO and CH4. In addition, TG-FTIR was used to further observe the pyrolysis process of WPCB and to track the components of gasses escaping from the pyrolysis process, namely CO2, phenol and substituted phenol. However, TG-FTIR detected bromine in the gas, suggesting that HBr gas may exist. Therefore, when the pyrolysis gas is recycled as fuel gas, it is recommended to first perform the de-bromination treatment of the pyrolysis gas to avoid HBr escape. [ABSTRACT FROM AUTHOR]

Carbonate sands (CS) have the potential to be utilized as construction materials, and their porous particles may bring unique thermal properties, which is critical for the thermal design of geosystems; however, this area of research is highly understudied. The present work provides a new contribution in this field by investigating the thermal conductivity (λ) of five uniform fractions of CS from the South China Sea, with emphasis on the influence of particle size and relative density of the sand. The impact of the size of particles on the index void ratios and thermal conductivity of the samples was profoundly different from that of silica sands. Contrary to silica sands, the extreme void ratio (emax, emin), which is critical for calculation of relative density, of the CS increased as the mean grain size increased. The maximum thermal conductivity of each fraction was negatively correlated with the particle size, and the thermal conductivity of the finer fractions exhibited higher sensitivity to the packing density. Literature models were found to be ineffective in predicting the thermal conductivity of the CS given the unique thermal energy transferring mechanisms of the porous particles. Two thermal conductivity models, stemming from semi-analytical and empirical approaches, were proposed in the light of providing useful guidance for the thermal designs that include CS. [ABSTRACT FROM AUTHOR]

Thermal conductivity is a basic characteristic of the heat conduction properties of subsoil. Previous research shows that soil thermal conductivity has complex correlations with many soil physical parameters, such as dry density, water content, mineral composition and particle-size distribution. In this paper, several artificial intelligence calculation methods are used to study the soil heat conduction mechanism and establish predictive models of thermal conductivity: an artificial neural network (ANN), adaptive neural network-based fuzzy inference system (ANFIS) and support vector machine (SVM). Their modelling performance was evaluated by several metrics: correlation coefficient (R2), root mean square error (RMSE), mean absolute error (MAE) and variance account for (VAF). Monte Carlo simulation was used to verify the robustness of the models, and the results of traditional empirical relationship models are used for comparison. The ANN, ANFIS and SVM models can accurately predict soil thermal conductivity, with R2 > 0.89, RMSE < 0.22 (Wm−1 K−1), MAE < 0.14 (Wm−1 K−1) and VAF > 88%. The ANN model had the best predictive accuracy, with R2 = 0.9535, RMSE = 0.1338 (Wm−1 K−1), MAE = 0.0952 (Wm−1 K−1) and VAF = 95.25%. The SVM model had similar accuracy, while that of the ANFIS model was lower. Monte Carlo simulations show that the SVM model provided the most robust predictions and that all three models were significantly better than the traditional empirical models. The SVM model is suggested as the best model for predicting soil thermal conductivity. [ABSTRACT FROM AUTHOR]

Increase in seismic events around the world has necessitated the evaluation of soil liquefaction potential since it adversely influences the stability of adjacent structures and poses a threat to lives and property. The first step in evaluating the liquefaction potential involves the estimation of the in situ state of sand and the state parameter as an index to characterize the behavior of sand. Due to the difficulty in obtaining high-quality undisturbed sandy samples for laboratory testing and evaluation, simplified equations based on the cone penetration test (CPT) are used for reasonable estimation of field behavior. In the present study, an optimized group method of data handling (GMDH)-type neural network was proposed to estimate the state parameter from CPT data obtained from the historical liquefaction database. A comparison was made between the measured and the predicted values of the state parameter to evaluate the performance of the proposed GMDH neural network method. A sensitivity analysis of the proposed model was also carried out to study the effect of input variables on the output variable of the proposed model. Additionally, the evaluation of in situ state and liquefaction potential of sand based on the state parameter was also presented and compared with the existing methods. Overall, the use of the GMDH model in evaluating the in situ state of sand and subsequent liquefaction potential assessment has shown promising results. [ABSTRACT FROM AUTHOR]

The settlement of highway embankments can directly affect the structural safety of road pavement. Comprehensive assessment of the long-term settlement characteristics of highway embankments is important in highway safety management. The present study conducted long-term settlement monitoring in an embankment of the Xi'an-Xianyang Highway in Shaanxi Province, China, that was constructed with recycled construction and demolition waste. Variations in sectional settlement, cumulative settlement, differential settlement, and settlement rates were made in a barricade section and an arc-shaped protective slope section. The maximum settlement observed in the barricade section was 51.75 mm, with the embankment exhibiting "basin-shaped" settlement. The maximum settlement in the arc-shaped protective slope section was 42.22 mm, and the embankment exhibited "W-shaped" settlement. Furthermore, there were two stages of great increase in the settlement rate. Based on the results, control standards for the sectional settlement of embankments constructed with recycled construction and demolition waste are proposed. Finally, a model for predicting the long-term settlement in road embankments constructed with recycled construction and demolition waste is established based on a Weibull distribution probability density function. [ABSTRACT FROM AUTHOR]

Background: Passiflora edulis is a tropical fruit with high nutrient and medicinal values that is widely planted in southern China. However, the molecular biology of P. edulis has not been well studied. There are few reports regarding the choice of reference genes for gene expression studies of passion fruit. Methods and results: By using three algorithms, implemented in geNorm, NormFinder and BestKeeper, we have selected ten candidate reference genes to explore their transcriptional expression stability in various tissues and under cold stress conditions. EF1 and HIS were stably expressed in five tissues. Ts and OTU were stably in vegetative organs. 50 S and Liom were stably in reproductive organs. The transcriptional abundance of EF1 and UBQ was stable in cold-treated and recovery treated leaf samples of P. edulis. In all samples, EF1 and Ts exhibited the highest expression stability. Evaluation of selected genes using simple statistical methods (ANOVA and post hoc analysis). Overall, EF1 emerged as the optimum reference gene for qRT-PCR normalize in P. edulis. In addition, the qRT-PCR analysis revealed that expression of ICE1 increases with the duration of cold treatment. Conclusions: In this study, we successfully screened stable reference genes from 10 candidates in P. edulis and verified the results by analyzing the expression level of ICE1. The results provide reliable and effective reference genes for future research on gene expression analysis in P. edulis, and lay a foundation for follow-up research on functional genes in P. edulis. [ABSTRACT FROM AUTHOR]

Cutoff wall has been widely used as a barrier to prevent the migration of contaminants in aquifers. Hydraulic impermeability and homogeneity should be ensured before operation. The difficulties in the rapid evaluation of newly constructed cutoff wall lie in high-quality sampling and time-consuming laboratory testing. In this study, piezocone penetration test is used to evaluate the barrier performance of a newly built cutoff wall. A Bayesian approach combined with genetic algorithm is adopted. The weak layers of cutoff wall are identified using excess pore water pressure data. The causes of impermeability defect are quantitatively characterized through optimized model parameters. Then, through comparison with the results of traditional soil behavior type based classification method, it points out the inapplicability of traditional method to evaluate the goodness of cutoff wall. Finally, the continuous horizontal hydraulic permeability profile is assessed by combining pore water pressure dissipation tests with adopted Bayesian approach. Results show that adopted Bayesian approach using excess pore water pressure can properly identify the weak layers of the newly built cutoff wall and reflect the causes. The analysis results can be used as guiding information for making remediation plans. [ABSTRACT FROM AUTHOR]

Delineation of contaminated soils is important for their remediation; however, reliable and efficient methods remain lacking. In this study, a contaminated site around an abandoned refuelling station in Southeastern China was investigated using resistivity piezocone penetration (RCPTU) and membrane interface probe (MIP) tests to evaluate the spatial distribution of organic contaminants. Various influences on the MIP results were analyzed, such as contaminant concentrations, the soil–groundwater interface and soil properties. Based on RCPTU and sampling results, MIP data were quantitatively evaluated in terms of relative percentage differences. Results from a photoionization detector (PID) and flame ionization detector (FID) were found to overestimate and underestimate the total petroleum hydrocarbon concentrations, respectively. In general, the PID was slightly more accurate than FID. Maps of regional contaminant concentrations were derived from geostatistical analysis of MIP data and were compared with contaminant concentrations measured in soil samples in the laboratory. This paper provides a method for interpreting MIP data with consideration of the influence of soil properties. It demonstrates the effectiveness of using MIP to determine contaminant distributions and increase the efficiency of site remediation programs. [ABSTRACT FROM AUTHOR]

The coefficient of consolidation (ch) of clay interpreted based on piezocone penetration test (CPTU) usually deviates from the actual values. This can be due to the inherent variability of ch, model uncertainty in the CPTU-based interpretation model, and test errors. Considering the importance of ch in designing the structures over clays, Bayesian inference approach combined with total probability theorem was proposed in this study to integrate the prior knowledge of ch with the project-specific test data to obtain the site-specific distributions of ch. Subsequently, a large number of equivalent samples were generated from the updated distributions of ch by Markov Chain Monte Carlo simulation. Then, Bayesian model comparison approach was developed to quantitatively compare the model proposed by Torstensson (model M1) with the model proposed by Teh and Houlsby (model M2). Finally, a sensitivity analysis was performed to study the effect of model uncertainty and data quantity on the updated distributions of ch. The results showed that model M2 was significantly better than model M1 after considering the rigidity index (Ir). The updated distributions of ch approximately exhibited the log-normal distribution, especially for model M2, which was less affected by the model uncertainty and data quantity than model M1. The proposed Bayesian approach in this study gives the updated distributions of ch from a limited number of test data and recommends model M2 for calculating ch. [ABSTRACT FROM AUTHOR]

Weakly expansive soil slopes are known sites of shallow landslides. In this study, soil samples of a natural slope in Zhenjiang, China, were tested by direct shear test during wet-dry cycles, and shear strength characteristics of weakly expansive soil under different wet-dry cycles were studied. The shallow stability analysis method of weakly expansive soil slopes was proposed for this analysis, which takes into consideration the influence of fissures. More than 60 two-dimensional weakly expansive soil slope stability analyses were performed using the strength reduction limit analysis method. The effects of fissure depths and slope angles on lower and upper limit safety factors and failure surfaces were discussed in detail. The results showed that the lower and upper limit safety factors decreased under different fissure depths and slope angles with the increase in wet-dry cycles. The sliding surfaces of weakly expansive soil slopes were all located at the layer with fully developed fissures. [ABSTRACT FROM AUTHOR]

In order to analyze the stability of soil-rock slopes with softening contact zones more accurately, a stochastic approach considering the proportions of rock blocks and their dimensional variability was proposed by this paper. Based on the proportions and gradation of rock blocks, the soil-rock slope models were generated with the rock block proportions form 0% (homogeneous soil slope) to 60%. Ten configurations of soil-rock slope models were analyzed for each VRBP considered to improve the statistical validity. More than 120 soil-rock slope stability analyses were performed using strength reduction limit analysis method, and the calculated results were compared with those obtained by without considering softening contact zones. The effects of rock block proportions and softening contact zones on lower and upper limit safety factors and failure surfaces were discussed in detail. The results show that the existence of softening contact zones weaken the effects of rock block proportions and rock block spatial variability on the soil-rock slope stability. The results show that the soil-rock slopes in practical engineering should be treated as heterogeneous materials, and a stochastic approach is very useful to provide reliable results than a deterministic approach in such heterogeneous slopes. [ABSTRACT FROM AUTHOR]

A comprehensive understanding of deformation characteristics and control measures for large-scale foundation pits in soft soil regions is of increasing importance to their risk assessment, design, and construction. In this study, the influences of the thickness of soft soil on the deformation of foundation pits are discussed based on statistical data from 24 foundation pits in floodplain areas of Nanjing, China. The mean maximum ground surface settlement around the pit in floodplain areas of Nanjing was 0.38%H, and the maximum ground surface settlement was observed at 0.48H. The maximum influence scope of ground surface settlement was about 3.5H, and the average maximum horizontal displacement of supporting structures was 0.23%H. On this basis, a model of ground surface settlement around the pit according to excavation depth for foundation pits in floodplain areas is derived. In addition, the influence scope around the pit and relevant control measures are proposed for the protection of surrounding underground structures and roads. [ABSTRACT FROM AUTHOR]

In the recent times, many studies have been devoted toward rectangular excavations but only a few studies have considered the "corner effect" in the optimized design of soil nail wall-retaining pile-anchor cable supporting systems, especially in large-scale deep foundation pit environments excavated by the central-island technique. Corner effect not only increases the construction costs but also may pose a risk to the safety and stability of such pits. In this paper, changes in the lateral displacement of retaining pile, soil at 1 m away from the foundation pit, crown beam, and the settlement of ground surface and surrounding buildings were extensively investigated based on the field measurements and numerical simulations of a large-scale deep foundation pit in Gaoxin zone, Xi'an, China. In addition, the supporting structure was optimized by considering the lateral influence zone of the corner effect. The optimization scheme proposed in this study not only satisfies the safety requirements of foundation pit supports, but also reduces the construction costs. [ABSTRACT FROM AUTHOR]

Buffer/backfill material is an important engineering barrier in a deep geological repository of high-level radioactive waste (HLW). Its thermo-hydro-mechanical (THM) performance is very important for the safe and stable operation of the HLW repository system. Natural graphite powder mixed with sodium bentonite forms a buffer/backfill material that can dissipate heat quickly and provide strong isolation. In this paper, the THM characteristics of bentonite–sand–graphite–polypropylene fiber (BSGF) mixtures, used as a buffer/backfill material, were studied through a series of laboratory tests. The influence of graphite and polypropylene fiber contents on thermal conductivity, swelling pressure, hydraulic conductivity, and strength properties of BSGF mixtures with different sand contents was analyzed. Experimental results indicated that the graphite content, the maximum graphite mesh number, and the initial dry density of bentonite–graphite mixtures influenced the thermal conductivity of bentonite–graphite mixtures. The addition of polypropylene fiber was found to enhance the shear strength and inhibit cracking without significantly affecting the expansivity, permeability, and thermal conductivity of the BSGF mixtures. This study provides a new buffer/backfill material that can improve the stability, functionality, and thermal efficiency of the HLW repository. [ABSTRACT FROM AUTHOR]

Water-air interactions caused by water level changes over a karst cavity can lead to sinkhole collapse. Declining water levels in a two-layered cover (clayey upper layer and sandy lower layer) above a karst cavity will lead to changes in the air pressure inside both the cover layers and the cavity. The change in air pressure can cause changes in the rate of water level decline and induce subsidence and collapse. In this study, a mathematical formula was derived and used to better understand the water-air interaction mechanism. Air velocity, vacuum variation in the cover, cumulative air intake, and elapsed time in the water level decline process are considered. A physical model was used to conduct laboratory simulations of the water-air interaction process and to determine the relationship between collapse and the water-air interaction. The main findings of this work are as follows: (1) Water level declines cause changes in air pressure both inside the cover and the cavity, and, conversely, the velocity of the water level decline was influenced by the variable air pressure; water-air interaction is obviously occurring. (2) With a low permeability cover layer, the declining water level mainly generates vacuum suction, but also erosion of the underlying high permeability sandy layer; vacuum suction and erosion can lead to subsidence or collapse of the cover. (3) Physical model simulations are useful for representing the phenomena of water-air interactions in karst cavities, and provide a practical way to understand the mechanism of collapse in karst terrain. [ABSTRACT FROM AUTHOR]

The hot deformation behavior of soft-magnetic Fe-6.9Si-0.03Y alloy was investigated by means of compression tests at temperatures between 480 and 660 °C to study the effects of deformation temperature on microstructural evolution, dislocation glide and mechanical properties. The dynamic recrystallization and the lower ordering degree were the main reasons for strain softening, eliminating the behavior of work hardening. The dynamic recrystallization decreased the density and configuration of dislocations and became obvious with increasing deformation temperatures. Meanwhile, increasing the deformation temperature promoted an increase on B2-APD size and the reduction in APB energy, and the content of DO3 ordered phases with high-brittle-hardness characteristic gradually reduced. The DO3→B2 transition decreased the ordering degree of alloy and enhanced the mobility and rearrangement of dislocations, leading to an improvement of plastic deformation. [ABSTRACT FROM AUTHOR]

Under the combination of heavy loading and high moisture content, the metastable structure of natural loess can easily lead to uneven settlement and damage the overlying infrastructure. Using traditional binder such as cement has harmful impact on the environment, especially due to resource consumption and carbon emission. This research has identified the feasibility of using red mud waste as a partial replacement of cement for loess subgrade treatment in terms of dynamic properties and environmental impact. The performance of loess treated with a combination of waste red mud (RM) and small amount of cement additive (C) is evaluated by considering the complex engineering geological conditions. The results show that dynamic stress (σd) and moisture content (w) have a more significant influence on the dynamic properties of RMC-treated loess compared with confining pressure (σ3) and loading frequency (f). Higher w shows a remarkable reduction in the dynamic load resistance of treated loess, yet the addition of RMC still can improve the microstructure and water sensitivity of loess. Specifically, the failure dynamic stress (σdf) and the maximum dynamic elastic modulus (Edmax) of the treated loess at higher w are found to be 100% and 400% higher than those of untreated loess respectively. RMC treatment also improved the dynamic cohesive (cd) value from 23.2 to 173.6 kPa compared with untreated loess. In addition, the leaching toxicity and radiation of RMC-treated loess indicate that it does not pose any risk to the groundwater. Finally, revised Monismith model has been developed based on the proposed formula for predicting power index b, which can be capable of describing the long-term deformation stability under cyclic loading. [ABSTRACT FROM AUTHOR]

Pressuremeter test (PMT) is conducted to obtain effective soil parameters such as limit pressure (PL) and pressuremeter modulus (Ep) that are frequently used in calculating foundation bearing capacity, settlement, and foundation behavior. However, the application of PMT in China was limited due to higher cost and time. There is a need for identifying a suitable method and establish models to predict reliable PL and Ep for interpreting or cross-checking soil parameters. Piezocone test (CPTU) offers an ideal test method to develop correlation models since it is widely adopted for geotechnical investigations in China. In this study, artificial neural networks (ANN) have been used to develop CPTU-PMT correlations. A total of 92 sets of sandy soil and 65 sets of clayey soil data from four testing sites were collected using CPTU and PMT. ANN was employed to develop 4 models, half of them considering effective overburden stress ( σ v 0 ' ), for predicting PL and Ep from CPTU data. The obtained ANN models were validated using the measured values of PL and Ep from pressuremeter tests and also the predicted values based on previous correlations. The comparison results show that PL and Ep values predicted by ANN models proposed in this study are more consistent with the measured values at testing sites. Additionally, foundation settlements were measured from a load test and compared with predictive settlements obtained using PL and Ep estimated by the proposed ANN correlation models. The results have shown that the CPTU results can be used to accurately predict PMT parameters and derive settlements. [ABSTRACT FROM AUTHOR]

Frequent landslides have generated huge security threats and economic losses all over the world. As an important anti-slip retaining structure, anti-slide piles can maintain the slope stability. The distribution of soil resistance acting on piles is the critical factor influencing the design of anti-slide piles, and the method of calculating the internal force is directly related to the landslide treatment and construction cost. However, limitations in the method of calculating the internal force of anti-slide piles still exist. In this paper, the influence of the internal force of anti-slide piles both considering and ignoring the soil resistance acting on the piles was verified using ABAQUS software, revealing that the soil resistance indeed had a significant effect on the anti-slide piles, especially when the gradient of the soil before piles was less than 40°. Therefore, the formula for calculating the internal force of anti-slide piles was proposed considering the soil resistance. Based on this formula, the optimum quantity of steel reinforcement and the safety factor were compared in practical slope engineering. This proposed formula considering actual distribution of soil resistance can be used for approximate calculation for anti-slide piles, which can reduce the construction cost, especially in large and neutral landslide engineering. [ABSTRACT FROM AUTHOR]

The identification of contaminated soils has gained increasing interest over the decades in the geoenvironmental issues. In this study, a probabilistic method based on the geostatistics and the reliability-based analysis is performed on the resistivity piezocone penetration testing data to evaluate the spatial distribution of the contaminants including the heavy metal ions and chlorobenzene over a site located in Shanghai, China. A sensitivity study revealed that the soil resistivity is a useful indicator of the presence of contaminants. Using the probabilistic method, a regional three-dimensional (3D) map of the probability that the soil is contaminated by the heavy metal ions or chlorobenzene is obtained based on the interpretation of resistivity data. Three selected sections of the resistivity-based 3D map are compared with those derived from the contaminant concentration data measured in the laboratory to demonstrate the effectiveness of the former. It is shown that the resistivity-based map is in accordance with concentration-based maps in a qualitative sense and provides useful information for the distribution of contaminants over the site. However, the resistivity-based probability shall always be judged with the results from the laboratory tests to draw a quantitative conclusion on the contamination status. Besides, it is also observed that the heavy metals may transfer over a narrower area than the chlorobenzene in the clay. The horizontal migration of contaminants is much more significant than that in the vertical direction, and it may be facilitated due to the presence of local geologic conditions. [ABSTRACT FROM AUTHOR]

Fe-6.9 wt.%Si steel sheets with different Ce doping were prepared by warm rolling and annealing. Fe-6.9 wt.%Si alloys' poor plasticity was mainly caused by the large amount of highly brittle DO3-ordered structure, and the significant improvement in their plastic deformation ability was found after adding rare earth Ce. The results reveal that the solid drag effect of Ce on the enhancement of dislocation slip reduces the difference of energy between antiphase boundaries and matrix and affects diffusion of Fe and Si atoms in DO3-ordered structure, hindering the nucleation and growth of DO3-ordered phases. λ-fiber textures are transformed into stable γ-fiber textures related to more frequency of ∑CSL boundaries because of an increment on Ce addition. The transgranular and intragranular cracks form in non-Ce-doped alloy with coarse DO3-ordered phases, and the ductile fracture zone characterized with some dimples occurs on the surface of 0.024 wt.% Ce-doped alloy, which indicates that the plastic deformation ability of Fe-6.9 wt.%Si alloy is significantly improved by rare earth Ce doping. [ABSTRACT FROM AUTHOR]

In this study, the effects of Ce addition on grain boundary character distribution, corrosion behavior and impact toughness of AISI 204Cu stainless steel were investigated. The results revealed that rare earth Ce affected the characteristics and size of inclusions, and the change in the austenite grain size was attributable to Ce multi-phase inclusions as the core of heterogeneous nucleation in stainless steel. The high adjacent probability of γ-fiber textures comprising {111} 〈110〉 and {111} 〈112〉 components was available for more ∑3n boundaries with increasing Ce contents, which was believed to have a contribution to the enhancement of corrosion resistance. Meanwhile, the austenite grain refinement and ∑3n boundaries increment were beneficial for the impact toughness improvement of Ce-added steel by increasing the difficulty of crack initiation and propagation. Adding excessive Ce caused a decline in the corrosion behavior and impact toughness of 204Cu stainless steel. [ABSTRACT FROM AUTHOR]

The shear wave velocity (Vs) is an important factor reflecting the dynamic characteristics of soil. Measured Vs values are always used in combination with laboratory parameters (e.g., effective confining pressure, σm′, and void ratio, e) and in situ penetration parameters from the standard penetration test (SPT) and piezocone penetration testing (CPTU). This study aims not only to estimate Vs based on correlations with other parameters in the absence of site-specific data, but also to outline relationships for estimation of soil properties. A database of seismic CPTU (SCPTU) and soil properties information for Jiangsu clays in East China was used to develop correlations between Vs and geotechnical parameters (vertical effective stress, unit weight, preconsolidation stress, site-specific parameters, undrained shear strength, and CPTU net cone resistance). Laboratory tests were carried out on thin-walled tube samples and high-quality block samples to measure soil properties. The results showed that the predicted values of Vs were in good accordance with measured values from field tests, especially the Vs values predicted from the CPTU net cone resistance. The relationship between Vs and the undrained shear strength showed better performance than the others. The good relationships between Vs and geotechnical parameters could be used to interpret engineering properties of Jiangsu clays for site investigation. [ABSTRACT FROM AUTHOR]

Difficulties in obtaining high-quality undisturbed soil samples have necessitated the increased use of cone penetration test (CPT) or piezocone penetration test (CPTU) to determine soil properties at geotechnical engineering sites. Undrained shear strength (a key parameter for most clay investigations) traditionally is evaluated by cone tip resistance or effective cone tip resistance. In this paper a method of using the clay's excess pore pressure was used to estimate the undrained shear strength. A correlation of pore pressure ratio and cone factor was discovered and compared with results from the published literature and with those from field vane tests. [ABSTRACT FROM AUTHOR]

Late Mesozoic granites are extensively distributed in the Luanchuan district of eastern Qinling and can be divided into two types: Late Jurassic to Early Cretaceous granites (ore-related plutons) and Late Cretaceous granites (Laojunshan batholith). This study presents new geochemical and zircon U-Pb-Hf isotopic data from the Shibaogou and Yuku plutons to provide robust constraints on the petrogenesis and tectonic significance of the late Mesozoic granites in the Luanchuan district. Zircon U-Pb dating results yielded weighted mean 206Pb/238U ages of 149.1 ± 0.8 Ma and 150.5 ± 0.8 Ma, which were interpreted as the crystallization ages of the Shibaogou and Yuku plutons, respectively. We propose that the late Mesozoic granites contain high concentrations of SiO2 and alkali elements (Na2O + K2O) and feature metaluminous to weakly peraluminous characteristics. Enrichment in light rare earth elements and large ion lithophile elements and depletion in high field strength elements are observed. Mineralogical and geochemical evidence reveal that the late Mesozoic granites are highly fractionated I-type granites with fractional crystallization of feldspar, plagioclase and accessory minerals (e.g., apatite and titanite or magnetite). Based on the Hf composition, we suggest that the parental magmas of the ore-related plutons were derived from remelting of the Taihua and Xiong’er groups with minor contributions of mantle-derived materials and that the Laojunshan batholith was generated by the hybridization of ancient crust- (Kuanping group) and mantle-derived components. Collectively, the above arguments indicates a tectonic transition from compression to post-collisional extension during the late Mesozoic, that was likely triggered by the continental collision of the North China Block and the Yangtze Block, which generated numerous contemporaneous granites and Mo-W-Pb-Zn-Ag-Au poly-metallic deposits. [ABSTRACT FROM AUTHOR]

The combined effect of B2 phase transfer and grain boundary character on mechanical properties of the Fe–6.5 wt% Si alloy was investigated. The microstructures and textures of the Fe–6.5 wt% Si alloy under four cooling modes were characterized by X-ray diffraction, transmission electron microscope, and electron backscattered diffraction. The results reveal that the maximum nano-hardness value (8.9 GPa) results from the two-step air-cooling sample, while for the two-step water-cooling sample, the minimum value (5.3 GPa) is achieved. The transformation of the B2 phase affected by the water-cooling process is a critical factor in obtaining the lower APB energy and eliminating the brittlenes. A large fraction of the coincidence site lattice boundaries that formed on the sheet experienced the two-step water-cooling process due to a uniform and sharp γ-fiber recrystallization texture comprising the {111} 〈110〉 and {111} 〈112〉 components, which enhances resistance to intercrystalline effect and improves mechanical properties in comparison with the two-step air-cooling process. [ABSTRACT FROM AUTHOR]

The disposal of scrap rubber tires has induced critical environmental issue worldwide due to the rapid increase in the number of vehicles. Recycled scrap tires as a construction material in civil engineering have significant environmental benefits from a waste management perspective. A systematic study that deals with strength and microstructure characteristics of the rubber-sand mixtures is initiated, and mechanical response of the mixtures is discussed in this investigation. Experiments were conducted to evaluate the effects of rubber fraction on the basic properties including mass density (ρ), stress-strain characteristics, shear strength, and unconfined compression strength (qu) of the rubber-sand mixtures. Additionally, scanning electron microscopy (SEM) was carried out to reveal the microstructure characteristics of the mixtures with various rubber fractions. A discussion on the micromechanics of the mixtures also was conducted. This study demonstrates that the ρ, friction angle, and qu decrease linearly with an increase in rubber fraction, whereas shear strain at peak increases. The stress-strain characteristics of the rubber-sand mixtures shift from brittle to ductile as the rubber fraction increase. These changes are attributed to remarkably lower stiffness and higher compressibility of the rubber particle compared with those of the conventional mineral aggregates. With an increase in the rubber fraction, the mechanical response of rubber-sand mixtures exhibits two types: sand-like material and rubber-like material. Rubber particle possesses the capacity to prevent the contacted sand particles from sliding at lower rubber fraction, whereas it transmits the applied loadings as the rubber fraction increased. This outcome reinforces the practicability of using recycled rubber tire-sand mixtures as a lightweight backfill in subbase/base applications. [ABSTRACT FROM AUTHOR]

In the present work, the evolution of microstructure and mechanical properties of high-strength low-alloy D6AC steel containing the Ce element was synthetically investigated by means of electron backscatter diffraction, scanning electron microscope, Transmission electron microscope, and tensile and impact tests. The experimental results show that adding a certain amount of Ce into HSLA-D6AC steel can refine grains and martensite laths, as well as increase the fine VC precipitates, which not only enhance the strength of the steel but also improve the toughness and plasticity. Meanwhile, the morphology of martensite in HSLA-D6AC steel changes from twin martensite to dislocation martensite. It is found that after adding Ce, HSLA-D6AC steel exhibits a distinct necking stage in the tensile test, and the impact toughness value increases from 83 to 136 J. With the appearance of some more and deeper homogeneous dimples, the quasi-cleavage fracture transforms into a ductile fracture characterized by microvoid coalescence, demonstrating that HSLA-D6AC steel with the Ce element achieves excellent comprehensive mechanical properties. [ABSTRACT FROM AUTHOR]

Under the process of urbanization in China, more and more attention has been paid to the reuse of heavy metal-contaminated sites. The shear characteristics of heavy metal-contaminated soils are investigated by electrical detection in this paper. Three metal ions (Zn, Cd, and Pb) were used, the metal concentrations of which are 50, 166.67, 500, 1666.67, and 5000 mg/kg, respectively. Direct shear tests were used to investigate the influence of heavy metal ions on the shear characters of soil samples. It is found that with the addition of heavy metal ions, the shear strength, cohesion, and friction angle of contaminated soils are higher than the control samples. The higher concentration of heavy metal ions penetrated in soils, the higher these engineering characteristics of contaminated soils observed. In addition, an electrical resistivity detection machine is used to evaluate the shear characteristics of contaminated soils. The electrical resistivity test results show that there is a decreasing tendency of resistivity with the increase of heavy metal ion concentrations in soils. Compared with the electrical resistivity and the shear characteristics of metal-contaminated soils, it is found that, under fixed compactness and saturation, shear strength of metal-contaminated soils decreased with the increase of resistivity. A basic linear relationship between C/log( N + 10) and resistivity can be observed, and there is a basic linear relationship between φ/log( N + 10) and resistivity. Besides, a comparison of the measured and predicted shear characteristics shows a high accuracy, indicating that the resistivity can be used to evaluate the shear characteristics of heavy metal contaminated soils. [ABSTRACT FROM AUTHOR]

The soil behavior type index ( I ) obtained from piezocone penetration tests (CPTU) has been widely applied in a series of geotechnical issues including the identification of soil stratum, estimation of soil properties and liquefaction analysis. To provide spatial statistics of I for the probabilistic analysis of these geotechnical applications, this paper investigated the inherent vertical variability of the I data using Gaussian random field theory. To achieve the analysis, 134 CPTU soundings were performed at the sites of four typical geologic formations. These formations included marine, Yangtze River Delta, long river floodplain and abandoned Yellow River floodplain deposits in the Jiangsu Province, China. Statistically homogeneous soil units (HSUs) were firstly identified based on a screening procedure. Then the probability density distribution of the I data in each HSU was studied using a formal normality test and the quantile plot method. Afterwards, the method of moment was used to estimate the three random field model parameters of I , including the mean value ( μ ), coefficient of variation (COV), and vertical scale of fluctuation ( δ ). It was shown that the normality hypothesis may be suitable for both raw I and the fluctuation components of I data in a qualified sense, whereas, in a strict sense, the feasibility of this assumption is complicated with about 50 % data passing the formal normality test. The COV of I data of the Jiangsu soils varies from 1.9 to 14 %. The δ of I profile ranges from 0.1 to 1.17 m. The impacts of the geologic formation and soil behavior type on the probability density distribution and random field characteristics of I data were observed as the normality, COV and scale of fluctuation values of I tend to be similar, provided that the soils are of the same geologic formation. Finally, suggestions for future selections of the normality hypothesis, coefficient of variation and vertical scale of fluctuation of I data are proposed. [ABSTRACT FROM AUTHOR]

Vibro-compaction is a ground improvement technique in which the weak or loose soil deposits are compacted by the vibrating probe or vibroflot penetration. The Piezocone Penetration Test (CPTU) has been found to be one of the best methods to assess the effect of ground improvement due to its continuous, reliable and repeatable data collected. The spatial variability of a liquefactionsusceptible site improved by vibro-compaction was assessed using random field theory. The CPTU soundings were conducted to characterize the variation of random field model parameters. Given the relatively high data frequency of the cone tip resistance in vertical direction, the vertical random field parameters are determined with the modified Bartlett random field estimation procedure. Due to the lack of data in horizontal direction, the horizontal random field parameters are evaluated using a less rigorous way of the autocorrelation. It is shown that the normalized cone resistance is a well estimator of spatial variability. The statistical results suggest that both Scale of Fluctuation (SOF) and the Coefficient of Variation (COV) varied in different way after vibro-compaction. [ABSTRACT FROM AUTHOR]

This paper presents details of a study that deals with determination of engineering properties and microstructural characteristics of a foundation soil (silt) sedimented in Jiangsu Province of China when it is stabilized by lignin-based industrial by-product. A series of laboratory tests were carried out with respect to evaluate the effect of lignin content and curing time on the overall soil properties including Atterberg limits, pH, unconfined compressive strength, stress-strain characteristics, secant modulus, and California bearing ratio. In addition, scanning electron microscopy, X-ray diffraction, and mercury intrusion porosimetry studies were conducted to understand the microstructural characteristics and stabilization mechanism of the stabilized silt. The results reveal that lignin has a great potential to improve engineering properties of silt and shows a promising prospect as a new environmentally friendly soil stabilizer. Curing time and lignin content have significant influence on the basic engineering properties and microstructural characteristics of the lignin stabilized silt. The optimum content of lignin for foundation silt in Jiangsu Province of China is approximately 12%. The precipitated cementing material is formed after stabilization of lignin with a period of curing. The stabilized silt switches over its response from a brittle to ductile material in the presence of lignin. Peak analysis results of the pore-size distribution curves demonstrates that the lignin stabilized silt exhibits bimodal behavior when the lignin content less than 8%, whereas it displays unimodal type when the lignin content is more than or equal to 8%. These observations provide enhanced understanding of lignin-based industrial by-product as a soil stabilizer at the foundation construction. [ABSTRACT FROM AUTHOR]

Ordered phases and ductility of Fe–6.5 wt% Si magnetic material were investigated under different rolling temperatures, and the constitutive equation of the warm deformation was established. The results show that at high rolling temperature, accompanying with the appearance of some shallow dimples, the intergranular fracture can be transformed into the quasicleavage fracture, which makes the ductility of warm-rolled sheets greatly improved. In the 450–650 °C rolling temperature range, the antiphase domains (APDs) of warm-rolled sheets are cut, the superdislocation density increases greatly with decreasing warm rolling temperatures, resulting in a decrease in APD sizes during warm deformation. Meanwhile, more B2 and DO3 ordered phases occurring in the matrix improve the long range order parameters, thereby significantly reducing ductility of the alloy. The work softening of Fe–6.5 wt% Si alloy is attributed to a contribution combining the sizes of APDs with ordered phases. [ABSTRACT FROM AUTHOR]

The use of the Seismic Piezocone Test (SCPTU) in geotechnical site investigation offers field assessment on stratigraphy and soil behavior. Compared with some traditional investigation methods such as drilling, sampling and field inspecting method or laboratory test procedures, SCPTU can greatly accelerate the field work and hereby reduce corresponding operation cost. The results of a site investigation on the soft, normally to slightly overconsolidated, Lixia River lagoonal clay deposit underlying several expressway lines, including a seismic piezocone penetration test, undisturbed sampling from an adjacent borehole, and laboratory testing, are reported. The determination of soil profile and the main geotechnical properties is facilitated by the use of seismic piezocone penetration test that can provide up to four independent reading with depth from a single sounding. The coupled use of normalized cone resistance and pore pressure parameter provides a simple and quick soil classification for highly interbedding of Lixia River lagoon ground. Comparison of the results reveals the validity of SCPTU tests to interpret the engineering properties of Lixia River lagoonal clay. These data will also be particularly useful for future local construction work. [ABSTRACT FROM AUTHOR]

As the core materials with excellent soft magnetic properties, Fe–6.5 wt% Si steel was fabricated by using the warm rolling process due to its extremely limited ductility and formability at room temperature. In this work, the effects of warm rolling reduction varying from 50% to 85% on the microstructure, texture, and magnetic properties of sheets were explored. The microstructure and texture evolution at the various processing steps were investigated in detail using optical microscopy, electron backscatter diffraction, and transmission electron microscopy. The results demonstrate that the finer recrystallization grains are accompanied with an increasing warm rolling reduction, and the final annealed sheets are characterized by strong α-fiber and γ-fiber textures. Accordingly, on the whole, as the increase of warm rolling reductions, the values of magnetic induction (B8, B50) in the final annealed sheets increase sharply up to a maximum value and then decrease to a certain value, and the values of iron loss (P15/50, P10/400) increase monotonically. [ABSTRACT FROM PUBLISHER]