Subjects: Mechanics >> Applied Mechanics submitted time 2023-03-20 Cooperative journals: 《应用力学学报》
Abstract： Based on the field investigation of dam break cases and flume model test , the numerical model ofovertopping break of concrete-face sand-gravel dam (CFSGD) is established to simulate the interaction a-mong water flow characteristics , sand-gravel materials , and concrete face slab. The model is mainly com-posed of three parts : ① Considering the erosion characteristics between the vortex water flow and sand-gravel materials , the RNG k-e turbulence model is introduced to simulate the reverse erosion of the vortexwater flow.2 Through the sediment transport formula and fluid volume method (VOF) traces the inter-face between sand and water erosion , and considers the pore characteristics of sand-gravel materials.3Based on the moment equilibrium method, the failure process of the concrete face slab under its self-weightand water loads is calculated.The numerical model is verified by the flume model test. 'The results showthat the numerical model established in this paper can accurately simulate the reverse erosion of the vortexwater flow on the dam during the failure process and the detailed evolution process of the face slab breach.The relative error between the measured data and the calculated peak breach flow , the development of thebreach of the rockfill body , the duration of the break and the length of the face slabs are all less than15% , which verifies the rationality of the numerical model.Compared with the parametric model , the nu-merical model of dam breach proposed in this paper provides more detailed results.
Subjects: Biology >> Ecology submitted time 2022-02-11 Cooperative journals: 《干旱区地理》
Abstract：基于野外人工模拟降雨试验和黑麦草全植被结构、根系结构及裸坡结构，通过设置不同雨 强（30 mmh-1、60 mmh-1和90 mmh-1）和不同下垫面坡度（1、3和5），对坡面产流产沙特征、水力参数分布变化及坡面侵蚀特征和水力特征关系进行了分析，揭示了不同草被结构类型下坡面产流产沙特征与水力特性。结果表明：随着雨强和坡度的变化，全植被坡面具有最小的产流产沙率，根系坡面次之，产流产沙率最大的则是裸坡坡面。黑麦草冠层的减流贡献率优于根系，冠层与根系的平均减流贡献率分别可达到62%和38%，减沙贡献率则是根系优于冠层，冠层与根系的平均减沙贡献率分别可达到37%和65%，以上产流产沙特征均揭示了草本植被冠层和根系在抑制侵蚀当中的有效性。水力参数中，雷诺数和水流功率是适用的2个水力指标，与产流产沙速率显著相关 （P）。本次研究可为不同草被结构下的水土保持效益提升以及水力特性的分析提供理论依据和试验参考。
Subjects: Environmental Sciences, Resource Sciences >> Basic Disciplines of Environmental Science and Technology submitted time 2020-06-21 Cooperative journals: 《干旱区研究》
Abstract：为了研究冻融期土壤水分与温度的变化及其关系，通过监测野外不同土地利用径流小区土壤水分与温度数据，分析了不同深度土层土壤水分和温度的时空变化规律，阐明了研究区土壤水分与温度的相关关系。结果表明：冻融期，坡耕地20cm土层含水率变幅最大，草地和林地均为40cm土层含水率变幅最大；坡耕地20cm土层含水率变异程度最大，而草地和林地的最强活跃层分别为：30cm和10cm ；草地最先进入冻结期和融解期，且冻结和融解时间逐层滞后；3种地类(坡耕地、林地、草地）土壤含水率与温度均呈二次函数关系。林地土壤水分与温度的相关性最强，更有利于黄土区土壤水-热保持，该结果可为黄土区土壤水分对植被恢复影响研究以及环境建设保护提供科学依据。
Subjects: Environmental Sciences, Resource Sciences >> Basic Disciplines of Environmental Science and Technology submitted time 2020-06-19 Cooperative journals: 《干旱区研究》
Abstract： 为了研究冻融期土壤水分与温度的变化及其关系，通过监测野外不同土地利用径流小区土壤水分与温度数据，分析了不同深度土层土壤水分和温度的时空变化规律，阐明了研究区土壤水分与温度的相关关系。结果表明：冻融期，坡耕地20cm土层含水率变幅最大，草地和林地均为40cm土层含水率变幅最大；坡耕地20cm土层含水率变异程度最大，而草地和林地的最强活跃层分别为：30cm和10cm ；草地最先进入冻结期和融解期，且冻结和融解时间逐层滞后；3种地类(坡耕地、林地、草地）土壤含水率与温度均呈二次函数关系。林地土壤水分与温度的相关性最强，更有利于黄土区土壤水-热保持，该结果可为黄土区土壤水分对植被恢复影响研究以及环境建设保护提供科学依据。
Hits
YES
Hits
Downloads
Comment