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The transportation infrastructure built in cold regions is mostly above frozen soil, whose stability is of concern, and which has been studied as a subgrade for highways and railways. Based on cryogenic cyclic dynamic triaxial tests, the subgrade frozen silt from the Qinghai-Tibet Plateau is taken as a research object. The dynamical characteristics of frozen silt are analyzed under different freezing temperatures, initial moisture contents, compaction degrees, and confining pressures. The results show that a hyperbolic constitutive model can well express the dynamic stress-strain response relationship of frozen silt under external dynamic loading. The dynamic shear modulus increased with decreasing freezing temperature, increasing moisture content, compaction degree, and confining pressure; the damping ratio had exactly the opposite relationship; and frozen silt energy consumption was gradually weakened. However, when the moisture content exceeded a certain threshold (11.4%), the damping ratio tended to increase instead. The unfrozen moisture content of frozen silt under different water contents was measured, which proved that the dynamic shear modulus increased due to the increase of ice crystals. In addition, variance analysis was introduced to analyze the significant influences of mechanical parameters. Four experimental conditions were compared for the influence volatility of the maximum dynamic shear modulus, final shear strain amplitude, and maximum damping ratio. Obviously, the dynamic properties of frozen silt were influenced by the freezing temperature and moisture content, followed by the compaction degree and confining pressure. Finally, the empirical formulas of the dynamic shear modulus and damping ratio were established by verifying the reliability and analyzing the experimental results.

As the main way of road transportation, highway plays an important role in the development of national economy. The optimum design mathematical model of expressway toll station is established based on the queueing theory. And this paper analyzed the performance of toll plaza, calculated the shape of toll plaza and lane confluence mode. Finally, we use LINGO software to solve the influence of the automatic driving vehicle on the design model

There is no common understanding on the influences of loess anisotropy on dynamic modulus and damping ratio. A series of laboratory tests were carried out on Xining intact loess using the GDS bidirectional dynamic triaxial test system. This study aimed to investigate the dynamic shear modulus and damping ratio of the Xining intact loess at different angles associated with the index plane. In addition, the difference between loess in Xining and other regions was also discussed. The following conclusions could be drawn based on the test results. Firstly, the anisotropy of the loess had a significant influence on the development of dynamic shear deformation and the dynamic shear modulus, indicating that it is necessary to keep the deposition direction of intact soil unchanged during sampling. Secondly, the increase of consolidation pressure reduced the effect of the anisotropy of loess. Higher confining pressure and a closer sampling angle to the natural deposition direction of soil resulted in higher dynamic shear modulus and slower rate of the development of soil dynamic shear deformation. In other words, the ability of soil to resist dynamic shear deformation became stronger. Finally, the damping ratio of Xining loess increased with the increase of dynamic shear strain. The increase rate of damping ratio of Xining loess was much quickly than that in other western regions, which could provide reference for the research on seismic zoning.

The reflections of high frequency (HF) radio waves between ionosphere and earth’s surface make long-distance information transmission possible. In this paper, the propagation process of radio signals was analyzed and the ionosphere was simplified. Considering the strength loss of signals that occurs in the travelling process and at the reflection points, two pairs of differential equations and integral equations were established to simulate the strength variations of HF radio waves and noises. A different equation of SNR was also developed, which utilized the failure threshold of signal-noise-ratio (SNR) as a criterion to evaluate the effectiveness of signals. Meanwhile, the pace of SNR attenuation was simulated when reflections happens on calm ocean, turbulent ocean, smooth terrain and rugged terrain.

In order to better explain the influence of induced anisotropy on the strength and deformation characteristics of loess, a complex stress path experiment of induced anisotropy of the remolded loess was carried out by using a hollow cylinder apparatus. Under the same condition of the intermediate principal stress coefficient b, the test carried out directional shear tests in the case of drainage. The effects and regularities of induced anisotropy on the strength and deformation properties of remolded loess were revealed. The results show that the remolded loess has obvious induced anisotropy, which cannot neglect the stress-strain relationship, strength and deformation of soil. The maximum difference in fail strength is 25% under different principal stress direction. Induced anisotropy has great influence on the stress-strain relationship of soil, which is the essence of soil properties. In some engineering practices, the result of stress-strain analysis of soil has great influence. Approximately isotropic remolded loess substantially eliminates inherent anisotropy. Therefore, this experiment will provide a good reference for the further study of soil anisotropy under complicated stress paths such as principal stress axis rotation.

In order to research the effect of different moisture content of intact loess in Qinghai on its strength and deformation characteristics, undrained triaxial compression are performed using the British GDS Standard Stress Path Test System. The results show that under the same moisture content, the failure strength of samples increases with the increase of cell pressure. Under the same cell pressure, the failure strength decreases with the increase of moisture content. The cohesive decreases with the increase of moisture content, but the change of internal friction angle is very small. By fitting the cohesion and internal friction angle with the change of moisture content curve, the formula of Coulomb shear strength cooperating moisture content is obtained. The formula has certain reference value for the design of foundations and ground treatment to practical projects in the Qinghai area.

To investigate the micro-mechanism for the anisotropy in the strength of intact loess in Xining, China, a series of consolidated-undrained shear tests were carried out, with a triaxial apparatus, on intact loess at different shear angles and depths. In this study, a scanning electron microscope (SEM) was used to examine sheared samples and generate their scanned images, which were used to analyze the morphology and the connection mode of soil particles qualitatively. Also, a particles and cracks analysis system (PCAS) was used to estimate the porosity, the probability entropy, and the porosity fractal dimension quantitatively. Test results reveal that the morphology of soil particles was mainly circular or oval at the direction parallel to the natural sedimentary surface. Soil particles were mainly in direct contact. The porosity of the soil was relatively lower when the pores were arranged in a regular pattern. With an increase of the shear angle, the morphology of soil particles gradually became schistose and the connection between soil particles turned into indirect point contacts. The porosity of the soil was gradually enlarged when the pores were not arranged in a regular pattern. The normalized pore size firstly decreased and then increased with the increase of the shear angle. Based on the analysis of the micro-mechanism for the anisotropy in the strength, the relationship between the macro-mechanism and the micro-mechanism for the anisotropy in the strength of intact loess was established and proved.

Duncan-Chang model describes the soil stress-strain relationship more accurately when the soil will be loaded. However, it will be inaccurate when the soil is in the unloading process, such as the pit excavation. In order to dispose of properly the Duncan-Chang constitutive model describing accurately the stress-strain relationship of the silty clay under the unloading condition so as to achieve the purpose of engineering application. This paper developed a further modified Duncan-Chang model, which consider intermediate principal stress, lateral unloading process, the parameter λ was introduced to the model; The result by taking the true triaxial test data of a typical silty clay shows that when λ=0.45, a new modified unload Duncan-Chang model for silty clay is effective in solving the problem of descripting unload stress-strain relationship test curves of the silty clay. And for the results further showed it is not suitable for using the sum of the intermediate principal stress σ2 and third principal stress σ3 is equal to 0.5 instead of the intermediate principal stress σ2 through the finite element calculation to the silty clay pit excavation.

A series of consolidated-undrained tests was carried out on compacted loess with a hollow cylinder torsional shear apparatus to investigate the stress-strain characteristics and the strength behavior of the compacted loess under different stress paths. Two kinds of stress paths were considered in these tests, including directional shear tests with fixed principal stress axes and shear tests under pure principal stress axis rotation. Test results reveal that the stress-strain curves of the compacted loess under these two kinds of stress paths followed a similar trend, in which two shear stages were observed. In the first shear stage, with the increase of the generalized shear stress, the generalized shear strain developed relatively slowly and the specimen of the compacted loess showed a rigid response. With the further increase of the shear stress, an obvious turning point appeared and the second shear stage started. In the second stage, the generalized shear strain began to develop rapidly and the specimen showed a ductile response. The results also reveal that when the directional shear was applied to the specimens of compacted loess under different principal stress directions, there was a large difference in the generalized shear stress - strain curves and the specimens showed significant anisotropic behavior. A compared with the specimens not subjected to the principal stress axis rotation, the specimens subjected to the principal stress axes rotation had remarkably higher strength. In addition, the specimens of the compacted loess had different levels of strength when they were tested at different shear rates. The decrease of the shear rate had a slight influence on the increase of the shear strength of the compacted loess.

According to the confined compression test in Xining area, the variation law of pressure on the collapsible deformation and compress deformation of loess is analyzed. The qualitative and quantitative analysis of the microstructure of loess samples before and after collapsing is carried out by electron microscopy. The relationship between the microstructure of the loess sample and the collapsible deformation is analyzed. The results show that:(1)with the increase of pressure, the deformation and compression of loess collapsing gradually become smaller, the soil is compacted, the strength is increased, the compressibility is weakened, the collapsibility is weakened or no collapsibility; (2) with the increase of pressure, the microscopic image observation of the sample before immersion, the structure of the undisturbed soil sample is relatively loose, the pores and particles are clearly distinguished, and the particle contour is relatively clear. After the sample is immersed in water, the arrangement of the skeleton particles becomes very tight, and the pore shape changes from large become small. As the pressure continues to increase, the microstructure of the sample gradually becomes dense; (3) the pressure increases with the increase of pressure before and after immersion in water. The arrangement gradually became stable, the particle distribution gradually concentrated and the degree of agglomeration became higher, and the proportion of pore area gradually decreased. The macroscopic collapse deformation and compression deformation of the loess before and after water immersion were consistent.

In order to investigate the effects of anisotropy of undisturbed loess on failure strength, dynamic shear modulus and damping ratio under cyclic loading, the dynamic characteristics of undisturbed loess in HaiDong area of Qinghai Province were studied by using the British GDS two-way dynamic triaxial test system. The results show that under the action of equal strain control cyclic load, as the number of cycles increases, the deformation of the sample gradually accumulates, the amplitude of dynamic strain decreases gradually, and the dynamic shear stress decreases. With the increase of dynamic shearing, the strain increases slowly and the strain hardening phenomenon appears. Different sampling angles have an important influence on the failure strength and dynamic shear modulus of undisturbed loess.

With the increase in global temperature, the frozen soil in the Qinghai-Tibet Plateau has been degraded to varying degrees, resulting in frequent road disease in the cold area, causing the bearing capacity of the frozen soil subgrade to be attenuated. In order to study the effects of the elevated temperature on the deviatoric stress and strain of the subgrade soil, the loading rate, dynamic stress amplitude, and frequency were introduced to simulate the working conditions of the highway, which ensure the negative effect of loading rate, dynamic stress amplitude, and frequency on the deviatoric stress. Then, using the orthogonal test method, for the 9 samples make the GDS dynamic triaxial test. The test results showed that the vibration frequency is the major effect factor on the deviatoric stress, deviatoric stress increased with the vibration frequency increased; the strain increased with the loading rate increased.

The variation of strength of fly ash geopolymer under different alkali activator modulus is studied. In this paper, three samples with modulus of alkali initiator 1.0, 2.0, 3.0 were prepared by laboratory test, and the unconfined compressive strength, SEM scanning and XRD analysis were conducted. Results show that the strength of the fly ash geopolymer negative correlation with alkali excitation agent module, with higher modulus alkali excitation agent, the strength of the polymer decreased obviously. From the micro perspective, the lower modulus of the sample of the microstructure appear more dense, gelling material produce more obvious at the same time. From the part of XRD, different modulus of the sample composition are same basically.

Aimed at researching intact loess mechanical properties in Qinghai area, this paper analyses these parameters through consolidated and undrained triaxial tests and SEM tests, and tests results are fitted linearly. The results show the maximum deviatoric stress increases with the increase of confining pressure when loess moisture contents are same. SEM images of loess clearly illustrate the close relative between moisture content and the pore distribution. The relationship between water content and shear strength index c and φ and ratio of pore area is nearly linear. Through using moisture content parameters, loess strength and pore ratio can be deduced by fitting linearly formulation, which has certain reference significance to the local engineering construction.

The collapsible loess in Xining area was tested by confined compression test to analyze collapsible and compression deformation of the loess. The researchers used electron microscopy to qualitatively analyze the microstructure of the loess samples before and after collapse. A comprehensive analysis of the relationship between the microstructure of the loess sample and the collapse deformation. The results show that: (1)with the increase of depth, the amount of collapse deformation and compression under the same pressure gradually become smaller, the soil is compacted, the strength is increased, and the compressibility and collapsibility are weakened; (2) due to the influence of loess stress history on its structure and collapsibility, with the increase of depth, the 6m loess exhibits less collapsible deformation and compressive deformation than the 3m loess; (3)with the increase of depth before and after immersion, the arrangement of pores tends to be stable, the particle distribution is gradually concentrated, the degree of agglomeration becomes higher, and the proportion of pore area gradually decreases. The collapsible deformation and compression deformation of loess before and after water immersion are consistent with the microstructure changes.

In this paper, the survival status of the sumatran rhinoceros was studied, the ecological game of the sumatran rhinoceros was put forward according to the critically endangered status, the differential dynamical system model of the sumatran rhinoceros and food was established, and the relationship between the parameters in the model and the land and environmental conditions was discussed. According to the value range of the four indicators, the ecological environment was divided into three conditions of food abundance, food shortage and critical state, so as to obtain the impact and requirements of the sumatran rhinoceros on the ecological environment. The results show that the sumatran rhinoceros lives in cycles under different land area conditions. Analysis from the perspective of the evolution of the ecological environment, the sumatran rhinoceros and food together form an ecological system, the abundant of food can cause sumatran rhinoceros populations, the number of the sumatran rhinoceros too much then can reduce the quantity of food, after reducing the number of the sumatran rhinoceros and will cause the increase in the number of food, this phenomenon is called ecological cycle, namely three environmental situation circulation phenomenon over time. Finally, according to the differential equation, migration is one of the ways that the sumatran rhino can continue to survive when the ecological environment changes.

The subgrade saline soil in a certain area of western Qinghai province was studied, based on the British GDS dynamic triaxial test system, the dynamic triaxial test under laboratory test was carried out to study variation dynamic stress-strain and dynamic shear modulus under the different temperature, frequency and confining pressure. The test results show that the dynamic stress-strain relationship is significantly affected by temperature change under cyclic dynamic load, followed by frequency and confining pressure. Under the same strain amplitude, the lower the temperature, the larger the dynamic shear modulus. When frequency and confining pressure increase, dynamic shear modulus also increases. Whereas, the influence of confining pressure on the dynamic shear modulus is more obvious, and the backbone curve development trend is steeper. Both maximum dynamic shear modulus and final shear stress amplitude increase with the frequency increases when temperature and confining pressure remain unchanged. Meantime, the maximum dynamic shear modulus curve is a convex shape, and the final shear stress amplitude curve is a convex shape at positive temperature,while which a concave shape at negative temperature. At constant frequency and confining pressure, the maximum dynamic shear modulus and final shear stress amplitude increase with the decrease of temperature. Curves of change trend are slower above 0°C, and steeper below 0°C.

In view of the high cost of the existing grouting materials, and at the same time the industrial production of a large number of fly ash, slag and other industrial waste can’t be effectively used. In this paper, the properties of fly ash slag cement with different ratios were studied through laboratory tests. Results show that the cement content in given conditions, with the increase of dosage of fly ash, initial setting and final setting time of cement paste with slow growth, the fluidity is growing, but the stone rate has obvious drop, on the compressive strength, the higher the slag content, is the early compressive strength, the greater the and the higher the dosage of fly ash, the late strength of cement paste were higher. This kind of grouting material has good working performance, can guarantee the project construction needs at the same time save cost, protect the environment.

Under the confined conditions, the influence of water content on the deformation characteristics of loess collapsing was studied by the indoor collapsibility test. The microscopic images were analyzed microstructural changes of the soil before and after the collapsing. The result shows that: (1) the higher the moisture content, the smaller vertical deformation of the sample after immersion in water under the same immersion pressure, and the smaller collapsibility. On the contrary, when the moisture water content is small, the main form of deformation is water immersion. After the collapse deformation, the amount of compression will decrease; (2) with the increase of water content, under the joint action of pressure and water, the soil structure tends to be dense, the particle filling area becomes larger, and the pore filling area decreases, and the pores are filled with clay and fine particles, and the connectivity between pores is reduced; (3) the average pore diameter, average pore area and average pore circumference of different soil samples after immersion are gradually reduced compared with the soil sample before immersion. The area is evenly distributed in each angular region and is related to macroscopic collapse deformation.

The reversible methanolysis of an azomethine C[double bond, length as m-dash]N in a series of copper(ii) Schiff base complexes has been investigated through combined spectroscopic, structural, and kinetic studies. Pentadentate copper(ii) complexes [L

In this paper, Tafel polarization technique is used to study the corrosion behavior of A3 steel basic magnesium sulfate, and then analyzing the ratio of raw materials cement, nitrites rust inhibitor and wet-dry cycle of basic magnesium sulfate corrosion of reinforced influence, and the steel corrosion behavior of basic magnesium sulfate compared with magnesium oxychloride cement and Portland cement. The results show that: the higher MgO/MgSO4 mole ratio will reduce the corrosion rate of steel; Too high and too low H2O/MgSO4 mole ratio may speed up the reinforcement corrosion effect; Adding a small amount of nitrite rust and corrosion inhibitor, not only can obviously reduce the alkali type magnesium sulfate in the early hydration of cement steel bar corrosion rate, but also can significantly reduce dry-wet circulation under the action of alkali type magnesium sulfate cement corrosion of reinforcement effect. Basic magnesium sulfate cement has excellent ability to protect reinforced, its long-term corrosion of reinforcement effect and was equal to that of Portland cement. Basic magnesium sulfate corrosion of reinforced is far below the level in the MOC in the case.

Water resistance of basic magnesium sulfate (BMS) cement has been studied in this paper. The solubility of main hydration of 5Mg(OH) 2 ·MgSO 4 ·7H 2 O in BMS cement has been analyzed by analyzing ions changes in 5Mg(OH) 2 ·MgSO 4 ·7H 2 O solution. Compressive strength and softening coefficient changes of BMS cement after immersing in water have been tested to evaluate water resistance of BMS cement. And crystal compositions and microstructure of BMS cement before and after immersing in water has been analyzed by XRD and SEM to study the mechanism. These results show that 5Mg(OH) 2 ·MgSO 4 ·7H 2 O possesses a low solubility at room temperature. Basic magnesium sulfate cement displayed an excellent water resistance based on additives in basic magnesium sulfate cement can inhibit the hydration of hard burnt MgO to sheet-like Mg(OH) 2 and reduce crystallization stress in BMS cement.

The influence of pH of the gelatin solution on the cycle performance of the sulfur cathode for lithium-sulfur batteries was studied. Scanning electron microscopy measurements revealed that the cathode prepared with pH 10.0 gelatin solution as a binder showed a uniform distribution. The charge/discharge experiments of the lithium-sulfur batteries showed that an initial capacity of 1137 mAh g -1 and a reversible capacity of 642 mAh g -1 after 30 cycles were achieved, which were higher than those of the cathodes prepared at pH 5.0 and 8.0. To understand the effect of the pH value of the gelatin solution on the cycle performance of sulfur cathodes, electrochemical impedance spectroscopy and X-ray diffractometry were carried out.