A method for computing slip-line fields in the case of cohesionless backfills with stress discontinuity was proposed. The potential failure zone is divided into the Rankine zone and the transition zone, and the Rankine zone is rigorously determined using the theory of plastic mechanics. The potential failure zone and the Rankine zone are then further divided into a series of triangular slices. On the basis of the force and moment equilibrium conditions of a typical triangular slice, the recurrence equation of the lateral force is established. Furthermore, the relationship between the failure surface inclination angle and the interslice force inclination angle is established by satisfying the Mohr–Coulomb criterion. An iterative procedure for calculating the lateral force of the triangular slices by changing the failure surface inclination in the transition zone is performed until the interslice force satisfies the stress condition of the transition zone boundary, resulting in a stress discontinuity line if the Rankine zone and the transition zone intersect and the intersection line satisfies the stress characteristics of stress discontinuity. Example studies are performed to verify the present method, which shows that the soil–wall interface friction has the most significant effect on stress discontinuity, and the location of the stress discontinuity line gradually approaches the backfill surface with an increase in retaining wall inclination.
Based on the conclusion that the effect of normal pressure on temperature distribution and the effect of temperature on soil–concrete interface friction are negligible, the finite-element model was established to analyse the characteristics of a pile enduring cyclic temperatures, adopting the sequential thermal coupling method. The temperature-induced additional displacements and axial forces along the pile depth were analysed, and the influences of temperature on the additional axial force distribution of the energy pile were analysed with different pile head loads. The analysis results showed that cyclic heating and natural cooling will lead to additional axial pile forces and displacements along the pile depth. It was concluded that loads applied at the energy pile top should not be heavier than the value at which plastic deformation at the pile end soil would be initiated and at which non-linear pile top settlement occurred.
A position conflict exists between Harbin Urban Rail Transit Line No.1 and the branch tunnel of "7381" civil air defense tunnel. Intense tunnel interaction occurs when Line No.1 is perpendicularly tunneled across the branch tunnel. The investigation of the interaction is necessary. A 3D numerical simulation is established using FLAC 3D and the vault deformation around the tunnel intersection is analyzed. The vault settlement of Line No.1 increases by 1.4 times during crosswise tunneling, while the vault settlement of branch tunnel increases 21.0mm in addition. The affected region of the tunnel intersection is further revealed. The affected length of the vault of Line No.1 and branch tunnel is 7.5 times the diameter and 6 times the width respectively. In combination with monitoring data, the reinforcement effect is studied at last. Both the vault settlement and surface settlement are well controlled in the tunnel intersection.
This paper reports a new method of nano/micro surface-texturing and the results of systematic studies of adhesion/stiction and friction properties on the textured surfaces produced by this method. Nano/micro-textured surfaces with various roughnesses were produced by low temperature aluminum-induced crystallization of plasma enhanced chemical vapor deposited (PECVD) amorphous silicon. Adhesion/stiction experiments on these nano/microtextured and non-textured surfaces were performed using two diamond tips under predefined displacement profiles with different maximum indentation displacements. Friction experiments on the textured and non-textured surfaces were conducted using the same tips under various normal contact forces. The adhesion/stiction forces and coefficients of friction (COF) of the textured surfaces were found to be much smaller than those of non-textured surfaces.
Prefabricated vertical drains (PVDs) have been used in finegrained soils remediation system to provide a higher flow rate.However, the migration and accumulation of the fine particles inthe soil result in the filter cake adjacent to the geotextile and thepore clogging in the geotextile. An analytical solution for soilflushing through a clogged geotextile with a filter cake isdeveloped. The results obtained by the proposed analyticalsolution agree well with those obtained from the finite differencemethod. Results from an illustrative example indicate that theformation of a filter cake at the surface of a geotextile is far moredisadvantageous to soil flushing than pore clogging within ageotextile. The 5-hour base concentration at the depth of z = 50mm for the case just considering the pore clogging in thegeotextile is just 1.06 times more than that assuming no filtercake and no pore clogging in the geotextile. When the poreclogging combined with a filter cake are considered, the 5-hourbase concentration at the depth of z = 50 mm increases by afactor of approximately 4.94.
Based on the grinding target profile of the rail and the grinding capacity of a single grinding stone, a numerical calculation method for rail grinding patterns that includes grinding angle and grinding power of each grinding stone of the GMC96 rail grinding train was designed and established. By means of this numerical method, the grinding pattern of each grinding pass was optimized and the rail head profile after grinding was calculated. Furthermore, a method for the evaluation of the grinding quality is provided. The results indicate that in multipass rail grinding, a sequence of grinding passes – where the greatest grinding effort is applied on the earlier passes, with the last pass applying reducing levels of grinding effort – produces the highest conformance to the target grinding profile. For example, when rail grinding is planned for two passes, applying 60% of the total grinding effort on the first pass and 40% on the second pass decreases the final grinding error by 7.3%.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Control of cell-to-surface adhesion has significant impacts on various biological and biomedical applications. In this study, the adhesion of Escherichia coli (E. coli) cells on nano/micro-textured surfaces produced by a unique surface texturing technique, aluminum-induced crystallization (AIC) of amorphous silicon (a-Si), was studied in order to control E. coli cell adhesion on glass substrates in an E. coli-based whole-cell chemical sensor. It was found that textured surfaces significantly enhanced cell-to-surface adhesion. Among the textured surfaces, nano/micro-textured surfaces showed advantage over micro-textured surfaces on the cell-to-surface adhesion. Study of the cell-to-surface adhesion mechanism suggests that the cell adhesion efficiency was controlled by the particle density of the textured surfaces.
Based on the background of urbanization in China, we used the dynamic spatial panel Durbin model to study the driving mechanism of ozone pollution empirically. We also analyzed the spatial distribution of ozone driving factors using the GTWR. The results show that: i) The average annual increase of ozone concentration in ambient air in China from 2015 to 2019 was 1.68 μg/m 3 , and 8.39 μg/m 3 elevated the year 2019 compared with 2015. ii) The Moran’s I value of ozone in ambient air was 0.027 in 2015 and 0.209 in 2019, showing the spatial distribution characteristics of "east heavy and west light" and "south low and north high". iii) Per capita GDP industrial structure, population density, land expansion, and urbanization rate have significant spillover effects on ozone concentration, and the regional spillover effect is greater than the local effect. R&D intensity and education level have a significant negative impact on ozone concentration. iv) There is a decreasing trend in the inhibitory effect of educational attainment and R&D intensity on ozone concentration, and an increasing trend in the promotional effect of population urbanization rate, land expansion, and economic development on ozone concentration. Empirical results suggest a twofold policy meaning: i) to explore the causes behind the distribution of ozone from the new perspective of urbanization, and to further the atmospheric environmental protection system and ii) to eliminate the adverse impacts of ozone pollution on nature and harmonious social development.
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