Boltzmann Function Research Articles

Research on the Non-Uniform Temperature Field Distribution of Q355B Steel for Grain Storage under Fire Conditions

To reveal the distribution characteristics of the non-uniform temperature field of structural steel under fire conditions, Q355B steel for grain storage was taken as the research object. A multi-channel temperature detection instrument was used to monitor the temperature distribution of Q355B test plate in real time under gas fire, and the distribution characteristics of the non-uniform temperature field of the steel were studied under different heat inputs. The results showed that the temperature changes within 600 mm from the flame point were significant, while the temperature changes beyond 600 mm were not sensitive. The peak temperature Tmax and the heating rate vr at the fire source points of each test plate increased linearly with the increase of heat input Q at the fire source. With the increase of distance d, the variation trend of the time tmax for each test plate to reach the peak temperature in the rolling direction, was the same. As d increased, tmax gradually increased and tended to stabilize. The average cooling rates vd1 and vd2 of each test plate decreased with the increase of d. The temperature distribution patterns of each test plate were the same. The Tmax-d curve of each test plate followed the Boltzmann function distribution, the Q-∆T followed a linear relationship, and the Q-d0 followed an exponential function relationship. By combining the three, a non-uniform distribution model of Tmax-Q temperature field under gas fire was obtained.

Simulating a Temperature, Stress And Strain FBG Sensor for Troposphere Layer

In this study, a simulation and design for a temperature (T) sensor are investigated by using the fiber Bragg gratings (FBG). The study investigated and characterized the FBG regarding maximum reflectivity, bandwidth, and the influence of applied strain on the shift in Bragg wavelength (λB). This is via measuring sensitivity of wavelength shift under strain in an optical sensing system. The response of FBG sensors was also investigated and optimized. Uniform FBG spectra and theoretical comparisons were conducted considering the influence of several selected external strain/stress (S) values: 101.325, 89.874, 79.495, 70.108, 61.640, 54.019, 47.181, 41.060, 35.599, 30.742, 26.436. The Optisystem 16 software is analyzing these two types of effects. The measured parameters, such as sensitivity, were determined by using a white light source. The light source operating wavelength was 1550 nm. This is to design the sensor especially for troposphere that have high sensitivity (1279.7472 pm/oC. The sensitivity obtained exhibited varying values between 1279.7472 and 1239.7551 for strain. The peak sensitivity observed is associated with 550 nm of wavelength. Result for measured sensitivity against S by the FBG sensor was 15.5087 pm/oC with sensor length 20 mm. While it was found equals 15.5131 pm/oC with sensor length 10 mm. T sensing is simulated for selected values (15, 8.5, 2, -4.5, -11, -17.5, -24, -30.5, -37, -43.5, -50 oC). Resulted sensitivity was found to fluctuate fitting sine, Long Normal, and Boltzmann functions, indicating large sensitivity for the simulated sensor responses.

Mutual replacement mechanism of inert gas with oxygen in coal and its effect on the low-temperature oxidation process of metamorphosed coal

The ability of inert gas to inhibit the low-temperature oxidation of coal is crucial for preventing spontaneous combustion of coal. In this paper, the replacement process of inert gas and O2 in coal and the low-temperature oxidation process of inert metamorphosed coal samples were studied. The results show that when significant O2 is displaced by the inert gas, the displacement process is inhibited and some of the O2 is reabsorbed into the coal, resulting in a decrease in O2 displacement. This decrease in the amount of O2 displacement is called the amount of O2 reverse displacement (Vi). One-time and continuous replacement experiments were designed to elucidate the mutual replacement process between inert gas and O2 in coal. The Vi can be calculated as the difference between the continuous replacement amount (VC) and the one-time replacement amount (VO). In the continuous displacement process, when CO2 is used for replacement, O2 is replaced in large quantities over a short period, and the amount of O2 is replaced following the ExpDec2 function. When N2 is used for replacement, O2 is consistently replaced over a long period. This trend follows the Boltzmann function. In the one-time replacement process for 40–100 mesh coal samples, the replacement amount of O2 reaches its maximum at 90 min. When replaced by N2, the reverse replacement process of O2 is obvious, and the maximum Vi reaches 60.53 %, while 17.69 % by CO2. When replaced by mixed gas, VO increases with the increasing CO2 content in the mixed gas. After inserting, the amount of indicator gases such as CO, C2H4, and C2H6 produced during the low-temperature oxidation of coal decreases significantly, and the activation energy increases significantly. As the inerting time increases from 0 to 150 min, the inhibition first increases and then decreases, but is always present. At 90 min, the indicator gas production reached the lowest value, and the activation energy reached the peak (E1 of the metamorphic coal after N2 and CO2 insertion increased by 54.67 % and 218.78 %, respectively, in contrast to the raw coal). The activation energy of the CO2-inerted metamorphic coal sample was 202.23 % of that of the N2-inerted metamorphic coal sample.

Spatiotemporal spreading characteristics of dust aerosols by coal mining machine cutting and "partition/multi-level composite field" atomization dust purification technology

To locally atomize the spatial confinement of primary dust generated by the shearer cut-off, the CFD-DPM mathematical model was used to simulate and analyze the wind-borne dust transport law, which resulted in the heavily polluted area of primary dust. A multi-level and multi-dimensional coal machine spray system was developed for the polluted area, its atomization effect was verified by using the TAB breakup model. The results show that the heavily polluted area of primary dust is mainly concentrated in the position of fully mechanized mining face Z=24–39 m area of shearer, and the average concentration is 738.2 mg/m³. The average concentration of droplets generated by the multi-level and multi-dimensional shearer spray system at the shearer drum is 0.66 kg/m³, with a percentage of droplets with particle size between 40 and 160 μm exceeding 85 %. The coverage rate of the shearer drum is 95 %. The relationship between droplet concentration and time is consistent with the Boltzmann function fitting model. Following the implementation of the multi-level and multi-dimensional coal machine spray system in the field, it was observed that the average reduction in dust levels was 90.9 % for total dust and 85.7 % for exhaled dust in the synthesized mining face.

MEDOC: A fast, scalable and mathematically exact algorithm for the site-specific prediction of the protonation degree in large disordered proteins.

Intrinsically disordered regions are found in most eukaryotic proteins and are enriched in positively and negatively charged residues. While it is often convenient to assume these residues follow their model-compound pK a values, recent work has shown that local charge effects (charge regulation) can upshift or downshift sidechain pK a values with major consequences for molecular function. Despite this, charge regulation is rarely considered when investigating disordered regions. The number of potential charge microstates that can be populated through acid/base regulation of a given number of ionizable residues in a sequence, N , scales as ∼2 N . This exponential scaling makes the assessment of the full charge landscape of most proteins computationally intractable. To address this problem, we developed MEDOC (Multisite Extent of Deprotonation Originating from Context) to determine the degree of protonation of a protein based on the local sequence context of each ionizable residue. We show that we can drastically reduce the number of parameters necessary to determine the full, analytic, Boltzmann partition function of the charge landscape at both global and site-specific levels. Our algorithm applies the structure of the q -canonical ensemble, combined with novel strategies to rapidly obtain the minimal set of parameters, thereby circumventing the combinatorial explosion of the number of charge microstates even for proteins containing a large number of ionizable amino acids. We apply MEDOC to several sequences, including a global analysis of the distribution of pK a values across the entire DisProt database. Our results show differences in the distribution of predicted pK a values for different amino acids, in agreement with NMR-measured distributions in proteins.

Influence of Early Hydration Process on the Hydrostatic Pressure Change of Cement Pastes at Different Temperatures.

In cementing operations, a rapid decrease in the hydrostatic pressure of cement paste is one of the main causes of early gas channeling. In response to this issue, tests were conducted on the variation in the hydrostatic pressure of cement paste over time at different temperatures (30 °C-180 °C), and it was found that the curve of its rapid decrease time point with temperature change conforms to the Boltzmann function. The relationship between the early hydration process and the microstructure of paste at 90 and 150 °C, as well as the changes in hydrostatic pressure, was studied using X-ray powder diffraction, thermogravimetry, and scanning electron microscopy. The results show that the hydrostatic pressure curve of the paste shows a trend of first stabilization and then rapidly decreasing at medium and low temperatures (30 and 90 °C). At high temperatures (150 °C), the pressure curve initially increases until stabilization, enters a stable period, and finally rapidly decreases. In the early stage of hydration induction, there is a large amount of free water between hydration products, and the hydrostatic pressure of the paste remains stable. In the process of hydrostatic pressure reduction, the microstructure of the paste develops from the particle hydration products to a "gel framework", which isolates the pressure transfer of part of the free water. During the acceleration period of hydration, the hydration products enhance the "framework" and reduce the porosity of the paste, completely cutting off the transmission of water pressure, resulting in a rapid decrease in the hydrostatic pressure of the paste. A method for predicting the rapid decrease in hydrostatic pressure of the paste was proposed using the hydration reaction process.

A new kinetic model on hydrolysis of sulfur mustard non-dissolved and dissolved in aqueous solution

This paper aims to establish a hydrolysis extent equation and rate dependence of initial and boundary conditions for sulfur mustard (HD) non-dissolved and dissolved in water by the following work. Firstly, non-homogeneous hydrolysis extent was found to be accurately described by a product of logistic with exponential convex growth function because of slow collision-complex formation between activated H2O and HD molecule to non-linearly couple with transition state decay, while the homogeneous has grown up only in an exponential convex function because of fast collision-complex formation to make its initial extent ratio extremely quickly close to unity. Secondly, initial non-temperature effects from (ethanol, acid, base) additives, HD concentration and droplet size, and rotation speed on hydrolysis rate could be summarized into a Boltzmann function of rate constant with initial molar free energy because of a thermal equilibrium distribution of internal quantum state at a given energy for bi-molecular structures before and after complexing. The results from 5 mL solution under vortex was nearly similar to the stirring 100 mL solution and would helpfully clarify the detoxification kinetics to establish a standard method for evaluating reactivity of aqueous decontaminants against chemical warfare agents at necessarily specified conditions.

Experimental Investigation on Bituminite Dust Suppression Characteristics of a Bonding-Wetting Composite Dust Suppressant.

In order to reduce the occupational health hazard of coal dust to miners, surface tension and viscosity tests and bituminous coal powder sedimentation experiments were conducted. A composite dust suppressant with bonding-wetting effects was developed. Meanwhile, based on the FTIR test and peak-differentiating curve fitting, the changes of peak areas of coal samples before and after dust suppressant treatment were investigated, with quantitative analysis on hydrophilic and hydrophobic groups. Gravity drop weight tests and Malvern particle size analyses were carried out. The particle size distribution was studied based on the Boltzmann function model. The characteristic particle size theory was adopted to analyze dust reduction performance and time's effect on the performance. Results show that the surface tension of the composite dust suppressant is 31.02 ± 0.09 mN/m with the viscosity being 84.60 mPa·s for the mixture of 0.1% SDS solution and 0.4% CMC-Na solution being 1:5. The ratio of the hydrophilic group of bituminous coal reaches 97.37% affected by the dust suppressant with a good wetting and cohesiveness effect. The characteristic particle size D 10 of dust increases by 11.77 and 46.67%, D 50 rises by 7.56 and 36.89%, and D 90 grows by 10.56 and 32.96%, respectively. The compressive strengths of the Shenmu coal sample and Lucun coal sample increase by 82.86 and 66.72% compared with that of raw coal after 48 h of dust suppressant treatment. The breakage degree at the end face of treated coal is smaller than that of raw coal. The composite dust suppressant makes the particles in coal more cohesive and effectively weakens the dust-producing property. Research results are of practical significance for improving the effect of water injection on dust reduction.

Extraction of vegetation disturbance range using aboveground biomass estimated from Sentinel-2 imagery in coal mining areas with high groundwater table.

Coal mining in regions characterized by high groundwater table markedly predisposes to surface subsidence and water accumulation, thereby engendering substantial harm to surface vegetation, soil, and hydrological resources. Developing effective methods to extract surface disturbance information aids in quantitatively assessing the comprehensive impacts of coal mining on land, ecology, and society. Due to the shortcomings of traditional indicators in reflecting mining disturbance, vegetation aboveground biomass (AGB) is introduced as the primary indicator for extracting the mining disturbance range. Taking the Huaibei Coal Base as an example, Sentinel-2 MSI imagery is firstly used to calculate spectral factors and vegetation indices. Multiple machine learning algorithms are coupled to perform remote sensing estimation and spatial inversion of vegetation AGB based on measured samples of vegetation AGB. Secondly, an Orientation Distance-AGB (OD-AGB) curve is constructed outward from the center of subsidence water areas (SWA), with the Boltzmann function used for curve fitting. According to the location of the inflection point of the curve, the boundary points of vegetation disturbance are identified, and then the disturbance range is divided. The results show that (1) the TV-SVM model, utilizing total variables and support vector machine, achieves the highest estimation accuracy, with σMAE and σRMSE values of 208.47g/m2 and 290.19g/m2, respectively, for the validation set. (2) Thirty-six effective disturbance areas, totaling 29.89 km2, are identified; the Boltzmann function provides a good fit for the OD-AGB curve, with an R2 exceeding 0.8 for typical disturbance areas. (3) Analysis of general statistical laws indicates that disturbance distance conforms to the general characteristics of normal distribution, exhibiting boundedness and directional heterogeneity. The research is expected to provide scientific guidance for hierarchical zoning management, land reclamation, and ecological restoration in coal mining areas with high groundwater table.

Sodium doping and control during the preparation of α-hemihydrate gypsum in NaCl solution

Transformation of phosphogypsum (PG) into α-hemihydrate gypsum (α-HH) in sodium salt solution is disturbed by the doping of Na+, which causes the frost of Na+ doped α-HH. In this study, the content evolution of Na+ impurities into α-HH was clarified during the hydrothermal process at 95 ℃, the frost phenomenon of hardened gypsum containing Na+ impurities was observed and controlled. The results show that increasing the initial NaCl concentration from 5 % to 25 % can promote the phase conversion of PG into α-HH within 30 min, but this will increase the Na2O content in the product from 0.08 % to 4.37 %, which is due to the formation of the undesirable phase Na2SO4·5CaSO4·3H2O. The content of Na+ impurities entering α-HH presents a non-linear increase with the NaCl solution concentration and reaction time, which can be well described by Boltzmann function. An obvious frost phenomenon of the hardened plaster of Na+ doped α-HH can be observed after curing 3 d, and the frost is identified as Na2SO4. This work further demonstrates the feasibility that the addition of CaCl2 in NaCl solution is an effective approach to control the doping of Na+ into α-HH, the Na2O content decreases to 0.97 % in the mixed solution of 17.5 % NaCl and 10 % CaCl2, this helps to eliminate the frost phenomenon and improve the mechanical strength of α-HH.

Study on Variation Law of Hazardous Areas in Goaf Based on Coal Oxidation Kinetics Theory

ABSTRACT Regarding various problems on safety production in coal mines, residual coal in goaf’s spontaneous combustion is extensive, determining its hazardous areas is critical to extinguish or prevent fires in goaf. Taking production practices at the 010803-working face of Wang Wa Coal Mine as background, a combined approach involving on-site experiments, laboratory tests, and numerical simulations is adopted to investigate “three-zone” spontaneous combustion as well as the distribution patterns of temperature fields in shallowly buried coal seams. The mathematical and physical models of spontaneous combustion in goaf are constructed. Upon oxidation of coal at low temperatures, experimental data about the intensity of release of heat and the rate of consumption of oxygen inform the construction of a kinetic model for coal oxidation in goaf. Utilizing field-measured data on air leakage, a distribution model for permeability within the working face’s goaf is constructed. To study combustion “three-zone” and temperature field distribution patterns in goaf under various air supply volumes, as well as to quantitatively analyze the relationship between the width and area of oxidation zones, the area of high-temperature areas, and the distribution of high-temperature sites in the goaf, with relation to the working face’s supply volumes of air. The results show that the maximum simulated air leakage in the goaf of the working face is 148.03 m3/min, with a relative error of just 1.4% compared to the measured value. Furthermore, validation confirms that the simulated oxygen concentration variation pattern closely aligns with the measured oxygen concentration. As the airflow rate at the working face increases, the oxidation zone width at the intake side gradually grows. While on the return side, it gradually decreases, resulting in a maximum width difference of 22.6 m. The goaf area’s concentration of oxygen exhibits an “S” shape distribution pattern. The overall temperature change range within the high-temperature zone of the goaf is 4.5 K, gradually migrating toward the deeper areas. As the air supply rate rises, oxidation zone area gradually decreases, exhibiting an overall sinusoidal distribution. Concurrently, the high-temperature zone area progressively expands, conforming to a Boltzmann function distribution. When the Air supply rate is 800 m3/min to 1120 m3/min, the areas of the two are linearly correlated with the air supply volumes. Under varying air supply volumes, the position of the high-temperature point within the goaf changes in both strike and dip directions, and the relative distance with the intake air corner follows an exponential function in both strike and dip directions. Through comprehensive analysis, it is concluded that the actual air supply volume on-site should ideally range between 800 m3/min and 1120 m3/min. This range effectively prevents and controls the hazardous area of spontaneous combustion in the goaf and optimizes the ventilation scheme.

Prediction Model of Spontaneous Combustion of Lignite in Zhalainuoer Mining Area.

A programmed temperature-increase experiment was conducted on coal samples from four coal mines in the Zhalainuoer mining area to improve the accuracy of predicting and forecasting lignite spontaneous combustion. The gases produced during the coal tests were analyzed, and logistic, exponential, Boltzmann, and fourth-degree polynomial functions were selected to develop predictive models for the gas data. Additionally, the Boltzmann function was used to predict the occurrence of fire. The results revealed that the initial appearance temperature of CO was approximately 50 °C, and it exhibited an exponential growth trend with increasing temperature. The initial appearance temperature of C2H4 was approximately 140 °C, which could serve as an indicator of coal entering the accelerated oxidation stage. Applying the selection principle to gas indicators, CO and C2H4 were identified as single gas indicators for lignite spontaneous combustion in the Zhalainuoer mining area, whereas CO/CO2 and C2H4/C2H6 were identified as composite gas indicators. Among the four functions, the Boltzmann function model exhibited the best fitting effect for CO and CO/CO2 within the temperature range of 0-200 °C. The values of the four parameters (A 1, A 2, dx, and x 0) were determined based on their statistical characteristics, and a functional equation describing the relationship between gas concentration and coal temperature was derived. This indicates that the Boltzmann function model can be effectively used to predict the spontaneous combustion of lignite in the Zhalainuoer mining area.

Research on Calculation of Porosity of Rammed Soil in Pingyao City wall (China) Based on Scanning Electron Microscope Images

ABSTRACT Porosity is an important parameter that affects the deformation, mechanical properties, and constitutive relationships of soil structures. It can be used as an important basis for deterioration research and safety assessment in the field of earth site protection. By collecting scanning electron microscope images (SEM) of the rammed earth of the ancient city wall of Pingyao, a world cultural heritage, and using software such as ImageJ and MATLAB to analyze the characteristics of the images from two-dimensional and three-dimensional perspectives, the relationship between threshold and porosity was studied and summarized. It was found that using the Boltzmann function eigenvalue as the control threshold can well characterize the two-dimensional porosity of soil. Using the idea of integration, the binary slice images with different thresholds are simplified and accumulated to construct a three-dimensional image porosity calculation model. Write a three-dimensional pore characteristic parameter program to extract the statistical image grayscale information and perform normal fitting. Based on the probability interval of the image grayscale distribution, calculate the threshold interval that can effectively reflect the three-dimensional pore characteristics of the soil. This research has important theoretical and practical significance for the protection research of earthen sites.

Crosswise heat flux and temperature profiles over downstream surface of gas-fueled pool fires in relatively strong wind

This paper reveals the crosswise profiles of heat flux and temperature over the downstream surface (ground) of a pool fire in relative strong wind, which was not well addressed in the past. Two square gaseous burners (25 cm, 30 cm) are used with propane as the fuel producing different heat release rates to simulate pool fires. The wind speed ranges from 1.5 m/s to 4 m/s (with 0.5 m/s intervals for various cases), concerning relatively strong wind conditions (Fr > 0.87). The crosswise heat flux profile first shows to be nearly stable (fluctuation less than 20 %) in the continuous flame region, then a sharp decrease in the intermittent flame region and finally goes to near zero. The temperature profile shows a similar trend as heat flux. For the near stable region, the flame boundary layer goes into the counter-rotating streamwise vortex pairs to form the streak like flames. And the counter-rotating pair (CVP) on the flame makes the streaks on the sides of the burner to be even larger, as verified by the CFD simulation. The heat flux is different under the streaks and troughs of the flame (higher under trough than in streaks), which interprets the fluctuation in the nearly stable region. Then the sharp decrease happens in the intermittent flame region. The flame half-width is obtained, which sits at about the middle of the sharp decrease region. And finally, for the position further away in the crosswise direction, the profile turns to be nearly zero. The crosswise profiles can be well represented by a Boltzmann function. The obtained experimental results and the proposed functions on the crosswise profiles of heat flux and temperature provide an essential base to estimate the heat feedback to the downstream surface of a wind-driven fire.

Impact Toughness Dependent on Annealing Temperatures in 0.16C-6.5Mn Forged Steel for Flywheel Rotors

For the application of forged medium-Mn steels on flywheel rotors, the effect of annealing temperatures from 300 °C to 650 °C on the impact toughness of 0.16C-6.5Mn forged steel was investigated to demonstrate the microstructural characteristics and austenite reverse transformation determining the impact toughness. The results obtained through standard Charpy V-notch impact tests at ambient temperature show that the impact absorbed energy holds at lower than 10 J almost constantly at annealing temperatures of 300 °C to 500 °C, and a representative intergranular fracture is presented. At an annealing temperature of 600 °C, the impact absorbed energy increases to 147 J, with the ductile fracture characteristics showing plenty of fine dimples, and the high impact toughness is attributed to the high volume fraction above 30% and the moderate stability of reverted austenite. Subsequently, the annealing temperature rises higher than 600 °C, the impact absorbed energy decreases, and the fracture morphology shows brittleness characterized by more flat facets of intergranular fractures and small quasi-cleavage facets, presumably corresponding to the insufficient transformation and twinning-induced plasticity effect due to weakening the Mn partitioning from quenched martensite to reverted austenite, which results in lower austenitic stability. Furthermore, the ductile-to-brittle transition temperature (DBTT) of the 0.16C-6.5Mn forged steel annealed at 600 °C, which holds the highest impact absorbed energy, and is explored for the possibility of flywheel rotor application in a service environment. The DBTT reaches −21 °C, obtained through the Boltzmann function, and the impact absorbed energy is approximately 72 J.

On development of lattice-Boltzmann method based multi phase flow solver

A numerical methodology based on lattice Boltzmann and level set function is presented to simulate the two-phase flows with stringent density and viscosity ratio. Two different strategies - single grid (SGLBLS) and dual grid (DGLBLS) are used. For accurate computation of interfacial forces in DGLBLS, the level set equations are solved on a uniform grid which is twice that for lattice-Boltzmann equations. The code validation and performance of SGLBLS and DGLBLS is carried on three different problems: Young’s Laplace law, 2D rising bubble and Rayleigh–Taylor instability. The results show that the representation of the interface is more accurate in DGLBLS with significantly less mass error - establishing it as an accurate method to handle stringent density and viscosity ratio. The comparison between DGLBLS and SGLBLS shows that the DGLBLS leads to a large improvement in the accuracy of the results with only slight increase in the computational cost.

The Effect of Magnetic Anisotropy on the Computed Specific Total Loss in Electrical Steel

Grain-oriented (GO) electrical steel (ES) laminates are still very important in industrial applications due to their remarkable crystallographic properties. Cores of large electrical machines and transformers are built from ES. The performances of these devices are significantly influenced by the properties of ES. The improvement of ES properties has been the subject of considerable research for many years. The phenomenon of magnetic anisotropy is highly non-linear, and it should be taken into account by the designers of magnetic circuits. The article proposes a modified model for calculating the angular properties of specific total loss of ES. The modeling takes into account the isotropic component (from classic eddy currents) and the anisotropic component, which is the sum of hysteresis and excess losses. For the directional loss modeling, the Boltzmann function was used. An analysis of the dependency of model coefficients on the frequency is presented.

Spatiotemporal heterogeneity of suprapermafrost groundwater dynamic processes in the permafrost region of the Qinghai-Tibet Plateau

Suprapermafrost groundwater fulfils an important role in the hydrological cycle of the permafrost region. Under the influence of the soil freeze–thaw process in the active layer, the dynamic process of suprapermafrost groundwater is too complex to be fully quantified, which has limited our understanding of the features of groundwater dynamic processes in permafrost regions. To bridge this gap, the dynamic characteristics of the suprapermafrost groundwater level were systematically observed, and pumping tests were performed under different topographic conditions (e.g., altitude, slope orientation, and distance from the river). The results showed that the differences in the heat distribution and recharge source of groundwater at the different altitudes and slope orientations determined the phase and threshold of the variation in the suprapermafrost groundwater movement state. There was a significant Boltzmann function relationship between the groundwater level and soil temperature. The groundwater level in the downslope during melting increased earlier and that during freezing declined later than that in the upslope part during the initial thawing cycle and the initial freezing cycle, respectively. The groundwater level on the shady slope decreased twice as fast as that on the sunny slope at the initial freezing stage. There was a favourable exponential relationship between the hydraulic conductivity (K) and soil temperature in the study area. On the sunny slope, K was higher than that on the shady slope, and K was higher in the area near the river than in the area far from the river. When the melting depth of the active layer reached 2/3 of the maximum depth, K reached its maximum value. The study results also revealed that when the soil temperature was reduced to 1–0 °C, a strong linear relationship occurred between K and soil temperature.

The analysis of seismic induced progressive instability and failure mechanisms: A case study

The 2008 Wenchuan Ms8.0 earthquake triggered a catastrophic landslide, i.e., the Daguangbao (DGB) landslide (1.2 ✕ 109 m3). Its shear failure occurred within a deep-seated (average depth of 400 m) saturated carbonate bedding fault in the Paleozoic Formation. The frequent seismic events in the tectonic belt make the landslide initiation mechanism more complex. Shake table tests were conducted on the DGB landslide to understand the coupling effect of multiple earthquakes, geology and hydrology. The results showed that the multiple earthquakes weakened the friction coefficient as the Boltzmann function on the sliding surface of the landslide. The friction law of the basal surface related to seismic energy was established and incorporated into the Newmark analysis. And the seismic energy consumed in the steep scarp surface release of landslide during an earthquake is also considered. It found that the traditional Newmark model overestimates the time for earthquake-induced landslides due to ignoring the steep scarp surface release stage. It proposed that evaluating pre-earthquake induced slope damage, and critical seismic energy for triggering co-seismic landslides are important for predicting post-seismic landslides.

The influence of palm fiber reinforcement on the cement content of vegetated concrete substrate under the condition of equal strength.

Vegetated concrete substrate (VCS) is a kind of ecological cemented soil, which has very wide application prospect in high and steep rock slope eco-protection. Cement is an important component of VCS, but it has high energy consumption and environmental pollution. Fiber reinforcement plays an positive role in improving the mechanical properties of soil, and its use as a substitute for cement content in VCS under the condition of equal strength is rarely investigated. In this study, the unconsolidated-undrained (UU) triaxial compression test of unreinforced substrate as blank control samples (BCS) and reinforced substrate as fiber reinforced samples (FRS) were carried out. The test results showed that the stress-strain curve of VCS can be divided into compaction stage, elastic stage, plastic stage and strain hardening stage. The average peak strength increased by 34.3kPa, 53.6kPa, 218kPa and 81.8kPa as cement content of VCS was 0%,4%, 6% and 8%, respectively. The relationship between the peak strength and cement content of VCS could be better fit by Boltzmann function. The mathematical model of fiber instead of cement in VCS under the condition of equal strength was established. It is found that there is a critical point of cement content according to the mathematical model. The cement of VCS can be completely replaced by plam fiber as the cement content is less than the critical point. While the cement content is higher than the critical point, the cement of VCS can be partially replaced by plam fiber. The decrease of average cement content was 17.23%, 19.00%, 24.27% and 25.34% with 0.2%, 0.4%, 0.6% and 0.8% fiber content in reinforced substrate, respectively. The theoretical method and interpolation method for fiber substitute cement content of VCS under equal strength condition were proposed, which can provide technical guidance for ecological slope protection engineering practice of vegetated concrete.