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30 September 2022, Volume 32 Issue 3 Previous Issue    Next Issue
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Column on Water Conservancy Engineering and Water Conservancy Informatization
Geotechnical Engineering Column
Civil Engineering Column
Romote Sensing and Ecological Environment Column
Mechanical Engineering Column


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Column on Water Conservancy Engineering and Water Conservancy Informatization

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Evaluation of Reservoir Dam Assets by Project Function State Method——Congratulations on the 70th anniversary of the founding of our alma mater WU Bo-qing 2022, 32(3): 1-6.  DOI: 10.16046/j.cnki.issn2096-5680.2022.03.001 Abstract ( )   PDF (268KB) ( )   China is a large reservoir country, with more than 98,000 reservoirs, which has created huge wealth for the society and is also a huge social asset so that the assets of reservoir dams should be evaluated. However, there is no professional evaluation method for water conservancy assets in China. If the conventional method suitable for ordinary assets is used to evaluate the assets of reservoir dams, the results often cannot reflect the reality. Based on the accumulated work experience of 25 water conservancy asset evaluation projects participated intermittently, this paper proposes to use the project function state method to evaluate the reservoir dam assets in order to explore the problem-solving. References | Related Articles | Metrics

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Study on the Evolution of Underground Reservoir Seepage in Coal Mine HUANG Hui, WANG En-zhi, LIU Xiao-li, LI Xiao-long, HU Xiao-long 2022, 32(3): 7-13.  DOI: 10.16046/j.cnki.issn2096-5680.2022.03.002 Abstract ( )   PDF (521KB) ( )   Mining underground causes the deformation and damage of overburden strata, and changes the original runoff of groundwater. Construction of underground reservoir in the goaf can not only protect the loss of groundwater resources, but also reduce the pollution of high salinity mine water to the ecological environment. In this paper, the self-developed simulation software is used to simulate the change of ground water in the mining process, and explore the evolution of seepage field in coal mine underground reservoir. Moreover, the safety of underground reservoir under different working conditions is revealed. The results can predict the flow characteristics of groundwater and provide theoretical support and technical guidance for groundwater protection. It is an important way to realize water conservation mining and efficient utilization of unconventional water resources in ecologically fragile coal mining areas. References | Related Articles | Metrics

Geotechnical Engineering Column

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Dynamic Response Analysis of Soil-Rock Mixed Subgrade under Moving Vehicle Load ZHAO Ya-jun, CAO Hao, SONG Yang, WANG Lei, ZHANG Zhi-bin 2022, 32(3): 14-20.  DOI: 10.16046/j.cnki.issn2096-5680.2022.03.003 Abstract ( )   PDF (503KB) ( )   In order to study the dynamic response of soil-rock mixed roadbed under vehicle load, a three-dimensional numerical model of asphalt pavement system was established by using finite element software ABAQUS.The moving uniform distribution load was used to simulate the vehicle load, and the response law of dynamic stress and deformation of soil-rock mixed roadbed under different driving speeds and vehicle loads was analyzed, and the depth of roadbed working area was determined.The results show that in the cross section of the roadbed, the vertical stress is the largest at the wheel action position, and the stress decreases when it is far away from the action point. The dynamic stress and deformation decay fastest in the depth of 1m. The influence degree of vehicle load on roadbed is greater than that of vehicle speed. With the increase of vehicle overloading rate, the dynamic stress response of subgrade increases, and the depth of subgrade work area is between 2.33m and 4.15m. References | Related Articles | Metrics

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Practice of Deep Foundation Pit Supporting and Monitoring Scheme for Zhangjiakou Mountain Broadcast Center Project of 2022 Winter Olympics WANG Shi-jun 2022, 32(3): 21-27.  DOI: 10.16046/j.cnki.issn2096-5680.2022.03.004 Abstract ( )   PDF (705KB) ( )   In view of the characteristics of pebbles in the deep foundation pit area of Zhangjiakou mountain relay center project of Beijing 2022 Winter Olympics, it is difficult to drive steel sheet piles into the supporting structure, and the use of reinforced concrete protective piles has long construction period, high cost and no environmental protection. Through scheme comparison, the support scheme of large-diameter steel pipe piles combined with small-diameter rotary jet grouting piles for water stop is finally determined, which can be recycled and reused so as to save the costs. In addition, considering the greater resistance of strongly weathered rock strata, the embedded depth of steel pipe piles is set at 1.4m, and a two-layer anchor cable system is designed. The calculation results show that the stress and deformation of the steel pipe pile meet the requirements, and the calculated horizontal displacement of the steel pipe pile is 5.16mm, which is very consistent with the measured value of 4.6mm, which indicates that the calculation of the supporting structure can reflect the actual stress state. As the rotary-jet pile is used as the stop-water curtain, there is no water at the bottom of the pit, which indicates that the water stop-water effect of the supporting structure is good during the rainy season construction. In addition, the construction monitoring scheme ensures the safety of the whole construction process and verifies the calculation results. References | Related Articles | Metrics

Civil Engineering Column

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Numerical Simulation of Air Flow and Heat Transfer in Electric Heating Drying Room Model LI Shu-qian, ZHOU Qing-qing, WANG Chen, WANG Hao-ran, YUE Liang-cheng 2022, 32(3): 28-36.  DOI: 10.16046/j.cnki.issn2096-5680.2022.03.005 Abstract ( )   PDF (856KB) ( )   In this paper, the instantaneous flow field and temperature field in the drying room model are analyzed by using the method of numerical simulation. The PTC drying room model experimental device is built, and the temperature data at typical locations are obtained. Based on the obtained temperature data, the reliability of Airpak numerical simulation results is verified. On this basis, by changing the placement position of PTC, it is found that the temperature of PTC substrate in staggered placement, longitudinal parallel placement and transverse parallel placement models reaches 199℃, 206℃ and 208℃ respectively, and the temperature at the grid is 57℃, 53℃ and 60℃ respectively. Through the comparison of temperature field and velocity field, it is determined that the best arrangement of PTC is horizontal parallel arrangement. References | Related Articles | Metrics

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Study of Prestress Loss on Cracking of Large Cantilever Concrete Covered Beam XUE Jiang, LIU Jin-cheng, LI Zi-lin 2022, 32(3): 37-43.  DOI: 10.16046/j.cnki.issn2096-5680.2022.03.006 Abstract ( )   PDF (531KB) ( )   With the increase of the service years of large cantilever prestressed concrete bridges, it is found in the process of operation inspection that there are many vertical or oblique and network cracks in the transverse side of some bridges. Taking a bridge in Shijiazhuang as an example, the factors affecting the prestress loss of large cantilever prestressed concrete bent cap are studied by using finite element software, and the influence of four factors such as local deviation of prestressed pipeline, environmental relative humidity, ultra early strength concrete and prestress tensioning age on the cracking of bent cap is analyzed. The results show that all factors have little influence on the tensile stress of concrete in the early stage. In the middle and late period, the influence of super early-strength concrete on the bearing capacity of prestressed girder is the greatest, followed by the relative humidity of the environment, then the tensile age of prestress, and finally the local deviation of the pipeline. Through the comparison of the above factors, the influence degree of the tensile stress of the cover beam in 10 years is determined so as to guide the construction, reduce the influence of construction factors on the tensile stress of the cover beam and improve the service life of the cover beam. References | Related Articles | Metrics

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Finite Element Parameter Analysis of Seismic Performance of Precast Reinforced Concrete Beam-Concrete-filled Steel Tubular Column Assembly Joints XIE Yong-ping, SUN Gang, YANG Xiao-hong, ZHANG LI 2022, 32(3): 44-51+69.  DOI: 10.16046/j.cnki.issn2096-5680.2022.03.007 Abstract ( )   PDF (778KB) ( )   In order to study the seismic performance of the new precast reinforced concrete beam-concrete-filled steel tubular column assembly joints,finite element simulation was carried out on the above joints, and the influence of the concrete strength grade, different steel pipe strength, different reinforcement ratio and stirrup reinforcement ratio on the joints was further analyzed.The results show that the joint has good seismic performance. With the increase of concrete strength grade, the bearing capacity, ductility and energy consumption capacity of the joint increase, and the increase range is less than 3%.Considering the cost performance, it is suggested to adopt C30 concrete strength of the joint. With the increase of longitudinal reinforcement ratio, the bearing capacity, ductility and energy dissipation capacity of the joints are improved, but the stiffness degradation is slowed down. The effect of steel pipe strength grade above Q420 on seismic performance is obvious. As the stirrup diameter increases, the joint energy consumption and specimen ductility weaken. Therefore, it is recommended that the diameter of stirrup be 8mm. References | Related Articles | Metrics

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Improvement of the Construction Process of Three-glass Two-cavity Curved Glass SUN Xiao-qiang 2022, 32(3): 52-57.  DOI: 10.16046/j.cnki.issn2096-5680.2022.03.008 Abstract ( )   PDF (436KB) ( )   During the construction of the three-glass two-cavity curved glass curtain wall, the secondary keel usually adopts mechanical bending arc, and the main keel and the T-shaped submerged plate are usually connected by channel steel. These two types of construction will lead to excessive installation errors and low pass rates for one installation. In order to improve the pass rate of one installation, the curved mold is used to bend the secondary keel in this paper, and the angle steel with two round holes in different directions is used to connect the main keel and the T-type submerged plate, and the results show that the pass rate of the first installation is increased from 85.6% to 96.2%, and the construction cost is greatly saved. This improved construction method has the advantages of good construction quality, short construction cycle and high economic benefits, which provides reference and reference for the subsequent construction of curved glass curtain wall. References | Related Articles | Metrics

Romote Sensing and Ecological Environment Column

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Landscape Pattern and Ecological Risk Prediction of Songhuajiang River Basin (Harbin Section) LIU Dan-dan 2022, 32(3): 58-62.  DOI: 10.16046/j.cnki.issn2096-5680.2022.03.009 Abstract ( )   PDF (324KB) ( )   In this paper, the Songhuajiang River Basin (Harbin section) was taken as the research area, and the landscape pattern prediction in 2025 was completed by Ca-Markov model; the landscape pattern metrics were extracted to analyze the landscape pattern in 2025; the landscape distribution in 2025 was divided into 6000 meter grids. The grid index of landscape ecological risk(LER) was constructed by the index of landscape vulnerability and the proportion of landscape type area combined with the weight assignment method of AHP. The spatial autocorrelation and spatial distribution of landscape ecological risk in 2025 were studied by using spatial variation function method. The results show that: ①from 2015 to 2025, the area of forest land, grassland and water area increased, while the area of construction land, cultivated land and unused land decreased; ②In 2025, the overall landscape ecological risk of the study area is relatively low, including 34.92%, 28.75%, 31.53%, 3.02% and 1.91% of the areas with lowest risk, lower risk, medium risk, higher risk and highest risk level, respectively; ③the overall Moran's I of the landscape ecological risk is 0.8242, showing a strong positive spatial correlation; the distribution of “low-low” value areas of landscape ecological risk is relatively concentrated. The range is distributed in the woodland landscape at the junction of Mulan county and Tonghe County, and the “high-high” value area is also concentrated, which is widely distributed in the construction land landscape of the main urban area.The results are helpful to improve the landscape ecological pattern of the study area,and provide scientific basis for rational use of land. References | Related Articles | Metrics

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Land Use Function Transformation and Associated Eco-environment Effects Based on Production-living-ecological (PLE)Spaces in the Miyun Reservoir Upstream Basin ZHANG Wei, CHEN Chen, LI Ze-yun, WANG Han-xu 2022, 32(3): 63-69.  DOI: 10.16046/j.cnki.issn2096-5680.2022.03.010 Abstract ( )   PDF (462KB) ( )   This dissertation is based on the territoria development model of “production space, living space and ecological space”. From the perspective that the transformation of land use function drives the change of regional ecological structure and service function, and with the help of “3S” technology, this paper uses the methods of land use transfer matrix, ecological environment quality index and ecological contribution rate of land use transformation to quantitatively analyze the 2000-2019 changes in land use, transfer characteristics and ecological environment effects in Zhangcheng area, northwestern Hebei province, in the upper reaches of Miyun Reservoir.The results show that: (1) From 2000 to 2019, the overall land use in the study area was characterized by a decrease in the area of agricultural production land, and a continuous increase in forest-grass ecological land and urban/rural living land. (2) The overall ecological environment index showed a steady and slightly increasing trend from 0.7227 in 2000 to 0.7261 in 2019. It can be seen that the ecological environment index is relatively high, which mainly benefits from the unique woodland and grassland resources in the study area. (3) There are two phenomena of improvement and deterioration of the ecological environment quality index in the process of land use transformation. Ultimately, the two offset each other into a growth trend. During the study period, the dominant factor affecting the change of ecological environment was the mutual conversion among grassland ecological land, agricultural ecological land and woodland ecological land. From 2000 to 2010, the main contribution to the growth of the ecological environment index came from the conversion of grassland ecological land and agricultural ecological land to forest ecological land, with a contribution rate of 91.65%. From 2010 to 2019, the increase in the ecological environment quality index was nearly four times that of the previous decade. In addition to the dominant factors, it also benefited from the conversion of a large amount of agricultural production land to grassland ecological land during the period, with a contribution rate of 31.97%. References | Related Articles | Metrics

Mechanical Engineering Column

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Solving Machining Path Planning Problem by Ant Colony Algorithm ZHANG Peng-cheng, WANG Wen-cheng, GONG Xiang, JIA Xin-li 2022, 32(3): 70-75.  DOI: 10.16046/j.cnki.issn2096-5680.2022.03.011 Abstract ( )   PDF (484KB) ( )   Aiming at the problem of tool path planning for hole group machining in mechanical processing, ant colony algorithm is used. Through multi-objective search and parallel computing, a shortest path is quickly found from many feasible machining routes as the trajectory of tool motion. The path can save the empty travel time in the machining process and improve the overall machining efficiency. By using the control variable method and orthogonal test method, combined with an example, the influence of five important parameters that need to be optimized in the process of algorithm implementation on the quality of the optimal solution is analyzed and studied, and the rule of action is explored, which provides a reference for further improving the algorithm optimization results and improving the algorithm. References | Related Articles | Metrics

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Design of Broken Belt Protector Based on the Technology Evolution-Resource Analysis ZHANG Wan-ming, GONG Xiang, LI Wen-bin, LI Hai, CUI Zhi-hao 2022, 32(3): 76-80.  DOI: 10.16046/j.cnki.issn2096-5680.2022.03.012 Abstract ( )   PDF (344KB) ( )   Aiming at the problems of untimely protection and failure of existing belt breaking protection devices for belt conveyors, this paper proposes a product innovation design strategy model based on technological evolution resource analysis. Based on TRIZ's technology evolution theory, the model makes a preliminary prediction of the technology development direction of the research product, then concretizes the technology prediction direction combined with the resource analysis method, puts forward the specific technology prediction scheme, and finally determines the scheme for further improvement of the product system. This strategy is applied to the innovative design of belt breaking protection device, which makes the overall structure of the product more compact, the performance more perfect, and can protect the conveyor belt more efficiently and reliably, which plays a guiding role for its future technical development trend. References | Related Articles | Metrics