最新刊期
卷 53 ， 期 3 ， 2021
- “在川藏铁路建设领域，专家提出了沟谷灾害链风险评估及防控对策，为灾害链全过程数值模拟评估方法提供新思路。”摘要：The valley disaster chain has recently attracted the attention of academics, which is also a huge challenge in the construction and operation of the Sichuan-Tibet railway transportation corridor. This research gives the definition and components of the valley disaster chains. By review valley disaster chain events that have occurred, the characteristics of the valley disaster chain were summarized, and their evolution models were summarized. The key factors that affecting the valley disaster chain were also discussed. Then, the risk assessment system, prevention, and control countermeasures of the valley disaster chain were proposed. The conclusions were obtained as follows: 1) The valley disaster chain is composed of potential disasters, primary disasters, secondary disasters (or series), and disaster-bearing bodies. Their typical characteristics were summarized as time continuity, spatial continuity, causality, and chain evolution. Based on the primary disasters, the valley disaster chain can be divided into 3 categories and 11 sub-categories, including the landslide disaster chains, the debris flow disaster chains, and the glacial lake disaster chains, which can be formed by a combination of three key processes (collapse/landslide-clastic flow/debris flow, landslide/debris flow blocking the river, and dammed/glacial lake outburst). 2) The formation of the valley disaster chain includes two modes. One is that the physical and mechanical properties of the primary disaster mass changed during movement to form secondary disasters, the other is that the primary disaster body changes the boundary of the secondary disaster body that induces secondary disasters. 3) The risk assessment of the valley disaster chain should pay attention to both the initiation mechanism of the primary disaster and the chain generation mechanism of the secondary disasters. It is suggested to strengthen the identification accuracy of the source of the potential disaster, develop the scientific understanding of the disaster transformation process, and quantify the disaster transformation mechanisms and critical conditions, establish a numerical simulation and evaluation method for the valley disaster chain, and carry out the evolution process and risk assessment of the valley disaster chain under future scenarios; 4) The prevention and control of the valley disaster chain is still in its infancy and should be improved based on the scientific understanding of the disaster chain. A comprehensive system for early identification, monitoring and early warning, simulation evaluation, emergency response, engineering governance, emergency avoidance, and risk management of the valley disaster chain is needed in the future.关键词：valley disaster chain;evolution models;disaster chain risk;dammed lake;outburst floods;Sichuan—Tibet traffic corridors2627|1189|25更新时间：2024-01-10
- “新发现的八宿巨型滑坡及其残留堆积体特征，初步分析了成因机制与演变过程，估算了滑坡方量。八宿滑坡是国内已经确认的方量最大的滑坡，为青藏高原地质环境认知和川藏铁路等工程建设提供了重要指导。”摘要：Giant rock avalanche is uncommon globally, but quite devastative, so its recognition is important both for deepening our understanding of regional tectonic background, and for disaster reduction and engineering safety. Based on remote sensing, UAV surveying and filed reconnaissance, a newly recognized Basu giant rock avalanche is reported, with its deposition features characterized, formation and evolution briefly analyzed and volume calculated. Major conclusions are summarized as follow. 1) Basu rock avalanche is developed within the Xiali—Basu rift valley of Bangong—Nujiang suture zone. Bedrocks are mainly marble set of the Paleozoic Jiayuqiao Group and metamorphosed sandstone and mudstone of Jurassic Mali Group. Most of its upper slope is composed of hard rocks dipping down the slope at a steep angle, while the lower slope is mainly of soft rocks dipping steeply into the slope. 2) The avalanche is about 7 200 m long, 4 800 m wide, covering both sides of the Lengqu River, and having an area of 22.5×106 m2 and an estimated volume of 3.5×109 m3. Its reserved volume can still reach about 1.4×109 m3, the largest one ever recognized and documented in China. 3) The avalanche is most likely triggered by a historical earthquake, as its debris is highly fractured and can climb up the right bank as high as over 600 m. That is, its sliding speed is quite high. The slide dammed the Lengqu River and the height of its landslide dam is about 185 m. The slide experienced a series of geomorphological process, as dam breaching, secondary Dora Kamiyama sliding, debris accumulation and erosion, and runoff-induced surface erosion, but its geomorphological features are still well reserved. Both the slide and the debris led to the route change of the Lengqu River. 4) Based on the evolution of both the slide and the Lengqu River, it is inferred that the slide occurred during Late Pleistocene, i.e. it is an ancient slide. 5) The recognition of Basu giant avalanche implies that our knowledge on the geological environment of Qinghai–Tibetan plateau is quite limited. For the construction of projects as Sichuan—Tibetan Railway, it is quite necessary to strengthen the investigation of both basic geology and engineering geology, and the evaluation of geo-hazard risk, so as to secure their safety during the construction and operation phases.关键词：Basu giant rock avalanche;deposition features;formation and evolution;volume estimation;implication for disaster reduction1905|1248|5更新时间：2024-01-10
- “在川藏铁路沿线滑坡灾害研究领域，专家通过1∶10的振动台试验，系统研究了含软弱夹层堆积体高陡边坡的失稳破坏现象和动力响应规律，为滑坡灾害防治提供了重要参考。”摘要：Aiming at the typical potential landslide disaster points along the Sichuan—Tibet Railway, a shaking table test of a high-steep deposit slope with weak interlayer was design and completed with a geometric similarity ratio of 1∶10. Systematic research has been carried out from the aspects of instability failure phenomenon and dynamic response of deposit slope. The conclusions are as follows: The landslide is a balanced and gradual process. At the beginning of the earthquake, under the influence of gravity and seismic force, the soil on the surface of slope began to peel off; as the ground motion continued, the top of the sliding body cracked, and the cracks on the surface of the sliding body increased and developed at the front edge locking section; finally, the locking section was damaged, the sliding surface was penetrated, and the sliding body slid out from the cutting outlet of the leading edge to form a landslide. Based on the PGA of the foot of slope, under the action of Wenchuan—Wolong seismic waves of different intensities, the PGA along the elevation of high-steep deposit slope had different degrees of magnification in the direction of the free surface and the vertical direction, the acceleration amplification effect on the free surface direction of slope was bigger than that on the vertical direction. Regardless of whether it was in the surface direction or the vertical direction of the slope, with the increase of the input ground motion peak value, the acceleration amplification factor gradually increased with elevation, and reached the peak value when the PGA was 0.4g. The inconsistency of the movement between the sliding bed and the sliding body was one of the main controlling factors that induced landslides. Before the accumulation body collapses, the acceleration peak value and the Fourier amplitude of the surface of the deposit slope were greater than that of the sliding bed, and the excellent frequency bands of the two were basically the same. When the accumulation body begins to collapse, the acceleration peak value and the Fourier amplitude of the accumulation body surface were smaller than that of the sliding bed, and the superior frequency band gradually shifted to low frequency, while the main frequency and amplitude of the Fourier spectrum of acceleration in the sliding bed were basically unchanged.关键词：shaking table;deposit slope;seismic response;weak interlayer1708|985|5更新时间：2024-01-10
- “在地震学领域，专家通过新榆林断陷塘探槽组开挖，揭示了鲜水河断裂带古地震破裂特征与复发行为，为川藏铁路施工及运营中的大震监测预警提供重要参考。”摘要：Rupture behaviors of (paleo) earthquakes are the basic data for seismic risk assessment and seismic design of major engineering constructions. Xianshuihe fault is the most active left-lateral strike-slip fault of the southeastern margin of the Tibetan Plateau. An earthquake of magnitude 7 or higher occurred every 30 years on average. Kangding Downtown area where the proposed Sichuan—Tibet Railway passing through is a relatively weak segment of Xianshuihe fault in paleo-seismic research. In order to obtain more detailed rupture characteristics and recurrence behaviors, we selected a depression pond at the Xinyulin site on the south side of Kangding new town to excavate the trench group. Two trenches arranged perpendicular to the fault pond were designed and studied, each trench with a total length of 18 meters, 3 meters deep, and 3 meters wide. Five meters wide rupture zone, seven sets (three categories) of sedimentary strata with clear boundaries and a series of paleoearthquake remains such as structural wedges were revealed in the trenches. According to the division of stratus and the relationship between faults and stratus, a total of 6 rupture events were summarized in the trenches, Combining the twenty 14C AMS dating results and historical seismic records, the events were limited in order: before 8714BC, 8304—6316BC, 6135—734BC, 118BC—27AD, 810—1230AD, and Kangding South M7¾ earthquake event in 1786. The modeled date shows that Near Xinyulin Village, the early recurrence interval of rupture events is relatively long (about 3000 years), and the activity has intensified since around AD, the recurrence interval has been shortened to about 700～1000 years, which is basically the same as the large earthquake recurrence habits in the North segment of Xianshuihe fault Belt. Comparison and synthesis with the previous research results, most of the events from Xinyulin to Ertaizi south of Kangding, Xianshuihe fault ruptured at the same time, but there may be some events that only ruptured near Ertaizi. Since 1893, Xianshuihe fault has entered a significant active period again. Destructive earthquakes have occurred in the northern segment of the Xianshuihe fault zone, while the southern segment of Kangding has been calming since the Moxi earthquake in 1786, and there is a possibility of strong earthquake with surface rupture in the future. Along the construction and operation of Sichuan—Tibet Railway, the monitoring and early warning of major earthquakes should be strengthened.关键词：Xianshuihe fault;paleoearthquake;Moxi segment;Kangding;seismic risk1719|918|2更新时间：2024-01-10
Sichuan—Tibet Railway Engineering and Environment
- “在建筑结构领域，专家利用ANSYS软件研究钢管混凝土桁架焊接管节点的应力分布，发现摩擦系数对热点应力集中系数影响有限。”摘要：In order to investigate the local stress distribution and hot spot stress concentration factors (HSCF) of welded tubular joints of concrete-filled steel tube (CFST) truss under different contact characteristics of steel-concrete interfaces, the Y-shaped welded tubular joints of CFST truss (the angle between the chord and the branch was 60°) were set as the research object. Utilizing the finite element software ANSYS, a finite element model of the tubular joint was established by using Solid45, Mass21, Targe170 and Conta173 elements. Considering nonlinear surface-surface contact relationship between the steel tubular wall and the filled concrete, internal squeezing or detachment caused by local deformation were simulated. Local contact deformation and stress state such as the contact gap, penetration depth, normal contact stress and tangential friction stress between the steel tubular and the filled concrete were obtained. The HSCF distributions of the chord and branch under three friction coefficients (0, 0.35, 0.60) were analyzed. The research results showed that the HSCF at the weld toe of the chord had a minimum value at the crown heel and a maximum value at the midpoint between the saddle point and the crown toe. Compared with the chord, the HSCF of the branch was generally smaller and the minimum value appeared at the crown heel. The maximum appeared between the saddle point and the crown toe. Under the action of the axial tension of the branch, the steel and concrete near the welding seam of the Y-shaped tubular joint were separated from each other, and the void area near the crown point was larger than that near the saddle point. The periphery of the void area of the saddle point was the most violent contact and compression area between the steel tubular and the concrete. The pressure was the greatest, and the concrete showed the most obvious supporting effect on steel tube. The friction coefficient had little effect on the distribution trend of the HSCF of tubular joint, and had a certain effect on the maximum value of HSCF.关键词：CFST truss;tube joint;local stress;HSCF;finite element analysis1708|818|0更新时间：2024-01-10
- “在泥石流减灾领域取得新突破，专家提出“阶梯+消力墩”排导槽，通过水槽试验验证其调控效果，为解决大坡降沟道泥石流灾害治理难题提供新方案。”摘要：The drainage channel plays a key role in the mitigation of debris flow. However, the traditional drainage channels are difficult to consider the problem of debris flow management in a large slope gully occurred in recent years. Therefore, a type of “step + baffle” drainage channel was proposed to deal with this question. Three geometric shapes of baffles (square, triangle, and trapezoid) were designed to test their performances for regulating the flow patterns, flow density and depth, grain size, velocity, and impact pressure based on the flume experiments. The results showed that the debris flow was lifted into the air by the baffles, and a wavy flow pattern generated in the drainage channel. Although the amplification effect on the flow depth was produced by the baffles, it can significantly reduce the debris flow velocity. The amplification effect of the square baffles was the most obvious, and the trapezoidal baffles had the weakest amplification effect. After the regulation of “step + baffle” systems, the density of debris flow and the particle size of solid phase at the exit decreased, and the trapezoidal baffle showed the strongest ability of blocking coarse and discharging fine. The impact pressure on the trapezoidal baffles was larger than that on triangular baffles. The first baffle of square baffle drainage channel endured the largest impact pressure of debris flow. The impact pressures on the second and third baffles in trapezoidal baffle drainage channel were both the largest among the three types of drainage channels.关键词：drainage channel;debris flow;flume test;regulation effectiveness1634|849|1更新时间：2024-01-10
- “在地震工程领域，专家基于耐震时程分析法，研究了配筋措施对高拱坝抗震性能的影响，为高拱坝抗震设计提供了科学依据。”摘要：In order to evaluate the effect of reinforcement measures on the seismic performance enhancement of concrete arch dams under different earthquake intensities, based on the endurance time analysis (ETA) method, the influences of whether the high-arch dam adopted seismic reinforcement measures on the damage and deformation indexes of the dam body under different earthquake intensities were studied. First, the ETA method, dam material constitutive model, transverse joint model and ground motion input method were introduced. Then the numerical models of arch dams with reinforced and non-reinforced seismic measures for high arch dams were established respectively, and the seismic durations of different earthquake strengths were generated based on ETA method. The damage distribution, joint opening and deformation response of high arch dams with reinforced seismic measures under different earthquake intensities were analyzed. The damage and deformation indexes of the high arch dam, such as the damage volume ratio, the average joint opening, and the crown cantilever deformation, were proposed. By comparing the dynamic response indexes of high arch dams with or without reinforcement, the influence of reinforcement measures on the response, damage and deformation index trend, correlation and dispersion of high arch dams was investigated. The calculation results showed that under different ground motion strength conditions, the reinforcement measures were effective to reduce the overall damage of the high arch dam, and had limited impact on the opening of transverse joints and displacement. The reinforcement measures could reduce the dispersion of damage and deformation indexes caused by earthquake randomness. At the same time, the normalized damage and deformation index revealed that the damage and deformation index had a certain correlation.关键词：ETA;high-arch dam;seismic reinforcement measures;damage deformation index;correlation1724|778|4更新时间：2024-01-10
- “在黄河泥沙改良领域，研究团队利用微生物诱导碳酸盐沉积技术，成功提升了黄河泥沙颗粒级配，为黄河泥沙应用提供了新思路。”摘要：A large amount of the Yellow River silt deposits in the middle and lower reaches of the Yellow River. The Yellow River silt has properties of small fineness modulus, poor particle gradation, and high mud content, which limit the use of the Yellow River silt in engineering. In order to improve the quality of the Yellow River silt and reduce the engineering defects caused by the use of the Yellow River silt, based on the characteristics of silt and microbial induced carbonate precipitation (MICP) technology, the Yellow River silt was quantitatively solidified and analyzed by using SEM and range analysis methods to study the effect of MICP technology on the improvement of Yellow River silt particle size distribution. The results showed that the specific gravity of the particles in the size range of 1 mm to 5 mm after MICP treatment was 45% higher than that of the first solidified sample, 70% higher than that of the initial sand sample in the same interval, and the contact number of particles in unit volume becomes larger, showing a multi particle cluster shape. Through the immersion test, the dispersion degree of coarse particles and aggregates in the sample was only 5%～10%. The optimum condition was that the particle size distribution of the sample was 5%～10%. The improved scheme includes 1∶1 bacterial to gum ratio, 1.5 mol/L cement concentration, 2∶1 urea to calcium source ratio, and CaCl2 as calcium source, in which the cement concentration was the main factor to improve the particle size distribution. Most of the CaCO3 crystals generated by mineralization were calcite crystal phase, and a large number of CaCO3 crystals were superimposed to form a bedding structure, and CaCO3 bridge was formed between sand particles, and fine particles were absorbed by cementation, thus increasing the size of silty sand and improving the Yellow River silt’s engineering property. This research provides a new idea for improving the Yellow River silt.关键词：the Yellow River silt;MICP;particle gradation;fineness module1730|772|0更新时间：2024-01-10
- “在水资源领域，专家构建了融合信息演化的水资源承载力评价模型，为区域水资源系统可持续发展提供解决方案。”摘要：The evaluation of water resources carrying capacity is an important part of sustainable development strategy of regional water resources system. However, the current evaluation methods often rely on static data to construct the correlation function between the research object and the level standard, and the information evolution is not adequately considered. To solve this problem, in this paper, the set pair analysis potential evaluation method and the partial connection number method were used to explore the dynamic balance between different levels, and a new water resources carrying capacity evaluation model was constructed. Firstly, the evaluation index system of water resources carrying capacity and the grade standard were obtained, and the ternary evaluation connection numbers of each research object were calculated. Secondly, based on the first-order partial connection number method, the support degree of the connection number to each level was represented by the sum of each component and the first-order evolution values of adjacent component to this component. Then, the preliminary evaluation of the research object can be realized by judging the grade of research object, mining the depth transfer between the identical and contrary components, and using the second-order partial connection number to expand the model. Finally, the water resources carrying capacity was evaluated and analyzed based on the above results. The results of applying the model to the evaluation of water resources carrying capacity of Hefei city from 2009 to 2018 showed that the water resources carrying capacity of Hefei city was in a critical state, but on the whole, it showed a steady and rising trend. The consistency with the previous studies verifies the rationality and effectiveness of the model and the comparison with the confidence threshold method show that the proposed model overcomes some subjectivity and has good expansibility.关键词：set pair analysis;connection number;set pair potential eigenvalue;partial connection number;water resources carrying capacity1539|838|9更新时间：2024-01-10
- “在地下水工程领域，专家通过分析非线性固结模型，成功获得弱透水层非线性固结的近似解析解，为实际工程沉降分析提供可靠方案。”摘要：The dropping of groundwater table by pumping may cause consolidation settlement of aquitard underlying aquifer, and the nonlinear compressibility and permeability of soils have evident influences on the consolidation deformation. Therefore, the nonlinear compressibility and permeability of soils have to be considered in the nonlinear consolidation model of aquitard caused by groundwater pumping, while difficulties exist in solving this consolidation model. Based on the analysis of the existing nonlinear consolidation models, an approximate analytical solution for the nonlinear consolidation of aquitard was derived, in which by adopting the classical nonlinear relationships and assuming a constant initial effective stress at different depths, an approximate analytical solution for one-dimensional nonlinear consolidation of soils caused by large area pumping of phreatic water layer were obtained using the method of separation of variables when the ratio of compressibility index Cc to permeability index Ck was not equal to 1. When Cc/Ck→1, the solution can be reduced to the existing one-dimensional nonlinear consolidation solution for the case of Cc/Ck =1. The solution was applied to the settlement analysis of engineering case, and the comparisons between theoretical and actual measurement results further showed that the solution is reliable for actual problems. Finally, taking the single-stage and constant-rate dropping of groundwater table as an example, the consolidation settlement curves of aquitard under different factors were calculated by using the above solution and the non-linear consolidation behaviors were analyzed. The results showed that when the value of Ck is constant, the larger Cc is (resulting in larger Cc/Ck), the slower the consolidation rate is, but the greater both the settlement at the same time and the final settlement are. When the value of Cc remains constant, the smaller Ck is (resulting in larger Cc/Ck), the slower the consolidation rate is, and the smaller the settlement at the same time during the consolidation process is, however it does not affect the final settlement of aquitard. The faster the dropping rate of groundwater table is, the faster the consolidation rate of aquitard is, while the final settlements under different dropping rate are same. The settlement rate grows with the increase in the final value of groundwater table (hc), whereas the influence of Cc/Ck on the consolidation rate becomes more evident. The larger the specific weight of soils (γ) is, the larger the settlement at the same time factor is, and the slower the dissipation rate of the excess pore pressure is, which indicates that γ has no influence on the final value of the excess pore pressure.关键词：dropping of groundwater table;nonlinear consolidation;variation of consolidation coefficient;analytical solution1467|775|2更新时间：2024-01-10
- “在冻土工程领域，专家建立了考虑温度变化和冻融循环作用的基桩p-y曲线模型，推导了水平荷载作用下基桩桩身内力与位移计算的有限差分解答，并通过试验验证了模型的可行性。研究发现，冻结温度和冻融循环次数对基桩受力与变形性状有显著影响，为冻土基桩设计提供了重要参考。”摘要：The influence of temperature and freezing-thawing cycles on the horizontal bearing mechanism of frozen soil foundation pile has not been clarified, and the calculation method of horizontal bearing force and deformation of foundation pile still needs to be further studied. Based on the existing experimental researches, a p–y curve model of pile foundation considering temperature and freeze-thaw cycles was established, and a finite difference solution for calculating the internal force and displacement of pile under horizontal load was derived. It was found that the p–y curve considering temperature and freeze-thaw cycle could reflect the horizontal bearing characteristics of piles in frozen ground. The lower the freezing temperature, the smaller the horizontal displacement and bending moment of the pile. When the freezing temperature T >–5 ℃, the internal force and displacement of the pile were greatly affected by the freezing temperature. However, when the freezing temperature T ≤–5 ℃, the influence of freezing temperature on the internal force and displacement of piles was very small. When the number of freeze-thaw cycle was less than 7, the horizontal displacement and bending moment of piles increased nonlinearly. After the soil around the pile underwent 7 freeze-thaw cycles, the horizontal displacement and the maximum bending moment of the pile increased by 51.7% and 16.1% respectively. When the number of freeze-thaw cycle was greater than 7, the horizontal displacement and bending moment of piles were not significantly affected by the number of freeze-thaw cycles.关键词：pile foundation;frozen soil;freeze-thaw cycle;horizontal load;p–y curve1610|962|2更新时间：2024-01-10
- “在钢管混凝土组合柱构件受剪承载力研究领域，专家通过试验与修正桁架–斜压场理论分析，验证了该理论的适用性，并与国际规范进行对比，为准确预估构件承载力提供了解决方案。”摘要：At present, the experimental studies, theoretical models, and calculation methods on the shear bearing capacity of concrete-encased concrete-filled steel tube (CFST) composite columns are insufficient. Therefore, the shear behavior tests were conducted to figure out whether the truss-arch field theory can be used to calculate the shear capacity of concrete-encased CFST composite columns. The results were compared with that of the Chinese standard T/CECS 188, the American standard AISC and the European standard EC4. Based on the different restraint conditions of the outer and core concretes, the modified truss-arch model used a steel tube as the boundary to divide the cross-sectional area of the members. which can consider the effect of steel tube restraint on concrete shear strength under axial compression. The results showed that the calculated values of the proposed calculation methods were in good agreement with 36 groups of the test data, which reflected the shear mechanism of the concrete-encased CFST columns, and the model calculation sensitivity was not greatly affected by the different design parameters. The ratio of the calculated value to the test value of most specimen was between 0.85 and 1.15. The calculated values using Chinese standard T/CECS 188 were generally lower than the test values, which cannot be accurately estimated to the actual bearing capacity of the columns. The dispersion of the calculated values using the American standard AISC or the European standard EC4 was large.关键词：CFST;composite column;shear bearing capacity;modified truss–arch model1561|1030|0更新时间：2024-01-10
- “在建筑抗震领域，研究人员通过低周反复加载试验，验证了新型钢板–纤维增强混凝土组合双连梁的优越抗震性能，为提高建筑结构的安全性和经济性提供了理论依据。”摘要：In order to improve the seismic behavior of the reinforced concrete coupling beam with small span-to-depth ratio, the influences of matrix material and steel plate were considered. A new type of plate–fiber reinforced concrete composite double (PFRCCD) coupling beam was proposed. The failure process, failure mode, bearing capacity, deformation capacity and energy dissipation of the ordinary concrete double (OCD) coupling beam specimen, plate-reinforced composite double (PRCD) coupling beam specimen and PFRCCD coupling beam specimen were studied. The results showed that, the shear failure occurred in the OCD coupling beam specimen, the bending shear failure occurred in the PRCD coupling beam specimen, and the good ductility and bending failure occurred in the PFRCCD coupling beam specimen. After adding steel plate, the bearing capacity of the PRCD coupling beam specimen at the peak point was nearly 1.56 times higher than that of the OCD coupling beam specimen. The bearing capacity of the PRCD coupling beam specimen differed little from that of the PFRCCD coupling beam specimen at peak point. The existing of steel plate decreased the internal force damage caused by the opening of the double beam, and the addition of fiber had little influence on the increase of the bearing capacity of the composite double coupling beam. At the failure point, the cumulative energy dissipation of the PFRCCD coupling beam specimen were 5.26 and 2.20 times that of the OCD coupling beam specimen and the PRCD coupling beam specimen, respectively. Compared with the other two specimens, the PFRCCD coupling beam specimen exhibited better bearing capacity, deformation capacity and energy dissipation capacity. Until the final failure of specimen, the concrete of the PFRCCD coupling beam specimen remained intact, so as to reduce or even avoid concrete cracking damage and reduce post-earthquake repair costs. It provided a theoretical basis for the practical application of composite double coupling beam.关键词：plate-reinforced composite double coupling beam;fiber reinforced concrete;seismic behavior;energy dissipation capacity;carrying capacity1528|727|1更新时间：2024-01-10
- “在水光互补系统领域，专家建立了光伏出力特性指标体系，提出了日内协调优化运行策略，为提升梯级水库群库容利用率提供解决方案。”摘要：In order to solve the problem that operation strategy of hydro-photovoltaic (PV) hybrid system is difficult to operate due to the uncontrollability and strong randomness of PV output, an intra-day optimal operation strategy with the index of fluctuating power ratio was proposed on the basis of influence analysis of PV output’s fluctuation characteristics on hydropower’s operation mode. First, an index system to describe both local and global characteristics of PV output was established, based on which the PV output scenarios were created by cluster analysis method. Then, considering both electric energy production and output fluctuation of the hybrid system, a new index named fluctuating power ratio was proposed, with which an optimized model was established. Third, combined with PV output characteristics, a particle swarm optimization (PSO) algorithm based on sigmoid function was proposed to solve the model. Finally, a case study was carried out for a series of small-scale hydropower stations developed in series and in parallel in a river basin in Sichuan Province. The results showed that the fluctuating power ratios in sunny, cloudy, and rainy days were within 0.05% after the complementary operation; compared with the optimization of hydropower alone, the access of PV improved the utilization rate of cascade reservoirs; and the proposed algorithm and model were proved to be feasible and scientific. It was demonstrated that the intra-day optimal operation strategy of hydropower in the hydro-PV hybrid system was as follows: The reservoirs discharged water to generate electricity while the PV output was small, then gradually stored water with the increased of the PV output, and started to discharge around the non-power generation period of PV until reaching the water stage at the end of the day.关键词：hydropower;photovoltaic power generation;complementary;strategy;cluster analysis;PSO algorithm1602|911|13更新时间：2024-01-10
HYDRAULIC & CIVIL ENGINEERING
- “在航天领域，研究人员开发了一种新型舱段对接系统，通过激光跟踪仪和并联机构实现自动对接，并通过模拟试验验证了其有效性，为空间站建设提供了技术支撑。”摘要：Aiming at overcoming the shortcomings in the current series docking technology and realizing automatic cabin docking, a cabin docking system was developed and a pose measurement and conversion method was put forward to provide reliable motion parameters for the parallel mechanism to achieve the docking task. Firstly, the coordinate system relation between the movable cabin and the laser tracker was matched through measuring relevant features. The coordinate system of the movable cabin was taken as the intermediate coordinate system, and equations of the relative pose relation between the movable cabin and the mobile platform as well as that between the movable cabin and the fixed cabin were constructed respectively. Because the analytical solutions of the relative pose equations which contain measurement errors, were difficult to obtain, the relative pose equations were constructed into custom scalar functions. Thus the problem of relative pose calculation was transformed into the optimization of each scalar function and the simplex method was used to solve each scalar function to gain the relative pose parameters. The position transfer conversion method was used to calculate the target pose of mobile platform. Finally, a simulation platform for cabin docking test was built, and the docking was successfully realized by using the above pose calculation results. In order to evaluate the docking effect, three groups of feature points on the end faces of the two cabins were measured after docking. The mean absolute deviation of the coordinate of the feature points set in the x-direction was 2.673 mm, which was consistent with the result of the chamfering of pins being slightly inserted into the pin holes. Meanwhile, the mean absolute deviation of the coordinates of the feature points set in the y and z directions were 0.120, 0.163 mm respectively, which is consistent with the result that the end faces of two cabins are facing directly and the holes are basically aligned with the pins, and to some extent, showed the validity of the proposed pose measurement method and the correctness of the calculated results.关键词：parallel mechanism;assembly of cabins;relative pose;pose measurement method1688|1060|0更新时间：2024-01-10
- “在精密测量领域，专家提出了一种激光跟踪仪检测三坐标测量机几何误差的新方法，有效提高了检测效率和精度，为精密测量技术发展提供了新方向。”摘要：Geometric error is an important error source of coordinate measuring machine (CMM). The geometric error measurement methods currently used have the problems of low efficiency and low accuracy, which seriously deteriorate the further improvement of the performance of CMM. Hence, a novel geometric error measurement and direct separation method of CMM using laser tracer was proposed. Firstly, the geometric error model was established based on the multi-body system theorem and homogeneous coordinate transformations. Furthermore, the mathematical model of geometric error measurement using laser tracer was formulated. And the geometric errors were directly separated based on the constraints of geometric error characteristics combining with the Levenberg–Marquardt method. Finally, the experiment of geometric error measurement of a CMM using a laser tracer and comparison experiments of single axis positioning error and volumetric positioning error were carried out. The results showed that the positioning errors ofX, Y and Z axis are –27.06, 43.75 and 36.76 μm, respectively, and the squareness error between X and Y axis was –82.89 μrad, which were the main error sources. The maximum volumetric error predicted of CMM was 74.64 μm, which was located in the limit area of the measurement volume. The identification results of geometric errors compared with the results measured by laser interferometer showed that, the maximum difference of three-axis positioning errors was 7.43 μm and the maximum difference of body diagonal positioning errors predicted was 10.51 μm. Compared with other laser tracking geometric error measurement method, X and Y axis volumetric positioning errors measured by this proposed method were the closest to the results measured by laser interferometer with the maximum difference of 5.3 μm which verified the effectiveness of this method. In addition, the 17 geometric errors of CMM could be measured within 2 hours by the method, which is of high speed and accuracy, and has a large application in the field of accuracy measurement of CMM and CNC machine tool.关键词：geometric error;laser tracer;constraints;volumetric positioning error1692|1360|3更新时间：2024-01-10
- “最新研究揭示了高强板材在矫直过程中残余应力的变化规律，采用数值计算和实验相结合的方法，验证了辊式矫直工艺能有效降低板材残余应力，为提高产品质量提供了重要参考。”摘要：In order to reduce the large residual stresses, which is generated in the production of high-strength plates during the quenching process and results in plate defects and product quality degradation. Numerical calculations of residual stresses, experiments and thermodynamic coupling simulations were carried out to study the changes of residual stresses during the whole process of straightening of Q960E high-strength steel. After quenching and heat treatment, a compressive stress of about 276.3 MPa was formed on the surface of the high-strength plate, and a tensile stress was formed in the opposite direction. The results showed that the roll straightening process could effectively reduce the residual stress of the sheet, and had a greater effect on the surface residual stress and a smaller effect on the core residual stress. This result also verifies the correctness of the calculation model for calculating the residual stress, which provides an effective calculation method for the straightening process to reduce the residual stress of the sheet.关键词：roller straightening;residual stress;numerical calculation1861|831|2更新时间：2024-01-10
- “在煤矿无轨辅助运输领域，专家提出了基于门限的转矩分配策略，通过限制门限分配转矩，提高车辆侧向操纵稳定性和能耗经济性，为解决FRID铰接车辆驱动转矩分配问题提供有效方案。”摘要：FRID (front and rear axle independent drive) can solve the problems of difficult arrangement and lack of power of heavy vehicles in trackless auxiliary transport of coal mine, but the driving and braking performance of this structure is constrained by the torque distribution strategy, How to realize dual motor torque coordinated control is the key and difficult point of this kind of problem. In order to improve the energy consumption economy of FRID drive type electric vehicle, a distributing control strategy for the driving torque based on the threshold was put forward. The lateral steering stability of the vehicle was taken as the constraint condition, and the threshold distributed torque was restricted to improve the lateral stiffness and lateral dynamic performance of the tire. In order to ensure the best driving force on the low adhesion road surface, the driving torque of the front and rear axle motor was controlled independently with the tire slip rate as the control target. In the MATLAB/SIMULINK environment, the torque distribution controller model and vehicle dynamics model of articulated vehicles driven by twin motors and twin shafts were established respectively, and the control effect under different road conditions was simulated and analyzed. Based on dSPACE platform, the hardware in-loop simulation test system was built to verify the real-time control performance of torque distribution controller. The results showed that the hardware in the loop test results and the software simulation results have good consistency, the threshold torque distribution strategy is a simple and effective economic torque distribution strategy, and the cycle energy consumption under given conditions can be reduced by 3%～5% compared with the dynamic distribution; When the lateral control stability was used as the constraint condition to limit the threshold distributed torque, the maximum slip rate of the inner wheel was controlled around 0.2 to improve the lateral cornering stiffness of the tire, thereby reducing the vehicle’s insufficient steering capacity and improving the vehicle’s steering ability.关键词：front and rear independent drive;torque distribution;energy consumption economy;handling stability;slip ratio1587|998|1更新时间：2024-01-10
MECHANICAL ENGINEERING
- “在卫星通信安全领域，专家提出了针对多窃听场景的波束成形方案，通过优化问题求解，有效增强了系统的安全性，为通信安全研究提供了新方向。”摘要：In order to enhance the security of multi-beam satellite communication system with multiple eavesdroppers, under the condition of available statistical channel state information, two beamforming (BF) schemes respectively for minimizing the total transmit power and maximizing the secrecy rate were proposed. Firstly, an optimization problem was formulated to minimize the satellite total transmit power while satisfying the secrecy rate requirement, and the analytical expression of optimal BF weight vector was obtained by adopting the Lagrange multiplier method. Then, two optimization problems were established to maximize secrecy rate with the constraint of total transmit power and per-antenna power budget, respectively. For the total transmit power constraint, the analytic expression of optimal BF weight vector was obtained by using generalized Rayleigh quotient method. For the per-antenna power constraint, the non-convex problem was converted into a convex one by introducing auxiliary variable, and further an iterative golden section-based algorithm was proposed to obtain the optimal BF weight vectors. Finally, the simulation results confirmed the effectiveness and validity of the proposed BF schemes. Meanwhile, the effect of the system parameters on the security performance was also analyzed. Compared to the traditional BF schemes, the proposed three BF schemes can obtain better secrecy performance.关键词：multi-beam satellite systems;physical layer security;beamforming;statistical channel state information1694|903|1更新时间：2024-01-10
INFORMATION ENGINEERING
- “在机械密封领域，专家建立了摩擦热-力耦合模型，为机械密封设计提供新思路。”摘要：The contact characteristics of end-face in the carbon graphite and tungsten carbide matched mechanical seal under dry operating condition were investigated. Taking account of the effects of the material properties of the seal ring and the mating ring, interaction between the end faces of contact asperities, direction of friction motion and frictional heat-flow, a three-dimensional thermo-mechanical coupling model of rotational friction between a rough entity and a smooth rigid entity was established. The instantaneous dry friction processes were numerically simulated by the ABAQUS finite element analysis software. The results showed that the true contact area of the rough face increased approximately linearly with the increase of the external load. Moreover, with the increase of external load and sliding velocity, the maximum contact pressure of the rough face was maintained in the range of 415～432 MPa, which is “self-limiting”. The temperature distribution on the sealing end face was uneven, the increase of external load and velocity will lead to the increase of the overall temperature of the end face. The position of the maximum temperature on the rough surface was affected by the local contact pressure, the local sliding velocity and the local heat transfer. It is necessary for the containment seal in API682 that the medium pressure should be less than or equal to 0.07 MPa, which could prevent the temperature rise of the sealing ring from being too high during dry friction. The studies provides a reference for exploring the thermal damage, friction and wear problems of the end faces of a mechanical seal, and may help the design of the mechanical seal under dry operating condition.关键词：mechanical seal;dry friction;contact characteristics;real contact area;contact pressure;fractal;rotation model1598|900|5更新时间：2024-01-10
- “最新研究发现，通过声波能量促进颗粒运动和气泡破碎，可改善气固流化床的流化状态和传热传质效果。实验结果表明，声波对气泡行为和床层流体力学特性的影响与流化气速密切相关。”摘要：Bubble behavior plays a decisive role in hydrodynamic properties and bed characteristics such as heat transfer, mass transfer in gas–solid fluidized bed. The dynamic characteristics of bubbles are important parameters for the simulation and design of a gas–solid bubbling fluidized bed reactor. Acoustic energy has the effect of promoting the particle movement and bubble breaking, which changes the dynamic behavior of bubbles, thus improving the fluidization state as well as the heat and mass transfer characteristics of gas–solid fluidized bed. Therefore, studying the influence of sound waves on the dynamic characteristics of bubbles is helpful to comprehend the acoustic fluidized bed. The glass beads with an average diameter of 55 μm were employed as raw materials in a half-cylindrical fluidized bed with a diameter of 120 mm. A gas–solid two-phase flow bubble measurement system with dual optical fiber probe was developed for measuring the bubble movement in the gas–solid fluidized bed. Four parameters of bubble fraction, bubble frequency, the average chord length and the mean rising velocity of bubbles at different fluidizing gas velocities were tested. Besides, the bubbling characteristics of an acoustic fluidized bed was further analyzed using the dual optical fiber probe. It was observed that the effect of sound wave on the behaviors of bubbles and the fluid dynamics properties of bubbles were related to the fluidizing gas velocity. Given a fixed sound frequency, the bubble fraction, frequency, the average chord length and the mean rising velocity of bubbles decreased with the increase of sound pressure level at low fluidizing gas velocity. While at high fluidizing gas velocity, the bubble fraction and frequency increased with the increase of sound pressure level, the average chord length and the mean rising velocity of bubbles decreased with an increase of sound pressure level. Given a fixed sound pressure level, the bubble fraction, frequency, the average chord length and the mean rising velocity of bubbles decreased first and then increased with the increase of sound frequency at low fluidizing gas velocity, reached the minimum value at about 80 Hz. While at high fluidizing gas velocity, the bubble fraction and frequency increased first and then decreased with the increase of sound frequency, reached the maximum value at about 80 Hz. The average chord length and the mean rising velocity of bubbles decreased first and then increased with the increase of sound frequency, reached the minimum value at about 80 Hz.关键词：sound-assisted fluidization;gas–solid two-phase flow;fiber optic probe;bubbles1569|772|1更新时间：2024-01-10
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Chaos Characteristics Analysis of Friction Vibration Signal in Running-in Process of Dry Gas Seal AI导读
“最新研究揭示了干气密封环磨合过程中的摩擦振动信号混沌特性，为监测和识别密封环端面磨合状态提供了新方法。”摘要：Running-in can prevent the end face of dry gas seal ring from occluding and prolong the service life of seal ring. The ensemble empirical mode decomposition method (EEMD) was used to extract the friction vibration signal between the end faces. The phase trajectories and chaotic parameters of friction vibration signals were obtained by phase space reconstruction. Principal component analysis (PCA) and maximum Lyapunov exponent discrimination method were used to verify the chaotic characteristics of friction vibration signal time series. The evolution trajectory of attractor structure and the change rule of correlation dimension of its characteristic parameters were explored. The results showed that when the rotational speed was 500 r/min, the load was 150 N and 450 N, the maximum Lyapunov indexes of each friction vibration signal time series were all greater than zero, and the principal component spectrum was basically a straight line with negative slope. So, it could be concluded that the friction vibration signal had chaotic characteristics. When the wear state between the sealing rings changed from run-off stage to stable stage, the corresponding change trend of friction vibration attractor was “convergence-stability”. The value of correlation dimension D of chaotic characteristic parameters changed from small to large with the running-in process. And when the friction was carried out to the normal wear stage, the value of D was kept floating in a small range to achieve stability. As a result, both chaotic attractor and correlation dimension D can reflect the running-in process between the ends of the seal ring, and can be used to monitor and identify the running-in state between the ends of the dry gas seal ring.关键词：dry gas seal;friction vibration;chaos1428|798|3更新时间：2024-01-10
CHEMICAL ENGINEERING & MATERIAL ENGINEERING
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