Visualization and early warning analysis of damage degree of surrounding rock mass in underground powerhouse

Based on the underground powerhouse of Shuangjiangkou hydropower station,Octree theory is adopted to define the indices of the microseismic(MS)spatial aggregation degree and the deviation values of MS count and energy.The relationship between the MS multiple parameters and surrounding rock mass instability is established from three aspects:time,space,and strength.Supplemented by the center frequency of the signal evolution characteristics,A fuzzy comprehensive evaluation model and the evolution trend of the MS event center frequency are constructed to quantitatively describe the early warning state of the surrounding rock mass instability.The results show that the multilevel tree structure and voxels generated based on the Octree theory fit relatively well with the set of MS points in threedimensional space.The fuzzy comprehensive evaluation model based on MS spatial aggregation and MS count and energy deviation values enables three-dimensional visualization of the potential damage area and damage extent of the surrounding rock mass.The warning time and potential damage zone quantified are highly consistent with the characteristics of MS precursors,with wide recognition and field investigation results,which fully validate the rationality and applicability of the proposed method.These findings can provide references for the early warning of surrounding rock mass instability in similar underground engineering.

Key rock mechanical problems of underground powerhouse in Shuibuya hydropower station

The complicated rock structures and the stability of surrounding rocks of the underground powerhouse were the key rock mechanical problems in Shuibuya hydropower station.In order to overcome the related rock mechanical problems encountered during its construction,a comprehensive research was carried out for the underground powerhouse in Shuibuya hydropower station based on a detailed geological survey.It covers the investigations on the initial in-situ stress distribution features,rock mechanical properties,engineering rock mass classifications by different methods,numerical modeling for stability and support analysis,proper measures for rock excavation and support.The results show that the rock excavations of the underground powerhouse under the given geological conditions can be controlled effectively.Some measures,suggested by the designers,are proved to be rational and effective.These measures mainly consist of:(1) the soft rock replacements by concrete in local area below the crane beam,(2) the shotcrete and reinforcement by rock bolts and anchor cables in surrounding rocks,and (3) 2 m concrete placement on the rock bench between adjacent tailrace tubes.The engineering practice shows that the treated surrounding rocks have a good overall stability.The deformation behaviors observed by safety equipments are within the designing limits.The research conclusions on the related rock mechanical problems,prior to the underground powerhouse excavations,are reliable.

Engineering rock mechanics practices in the underground powerhouse at JinpingⅠhydropower station

Based on the analyses of data obtained from the underground powerhouse at Jinping I hydropower station, a comprehensive review of engineering rock mechanics practice in the underground powerhouse is first conducted. The distribution of strata, lithology, and initial geo-stress, the excavation process and corresponding rock mass support measures, the deformation and failure characteristics of the surrounding rock mass, the stress characteristics of anchorage structures in the cavern complex, and numerical simulations of surrounding rock mass stability and anchor support performance are presented. The results indicate that the underground powerhouse of Jinping I hydropower station is characterized by high to extremely high geo-stresses during rock excavation. Excessive surrounding rock mass deformation and high stress of anchorage structures, surrounding rock mass unloading damage, and local cracking failure of surrounding rock masses, etc., are mainly caused by rock mass excavation. Deformations of surrounding rock masses and stresses in anchorage structures here are larger than those found elsewhere： 20% of extensometers in the main powerhouse record more than 50 mm with the maximum at around 250 mm observed in the downstream sidewall of the transformer hall. There are about 25% of the anchor bolts having recorded stresses of more than 200 MPa. Jinping I hydropower plant is the first to have an underground powerhouse construction conducted in host rocks under extremely high geo-stress conditions, with the ratio of rock mass strength to geo-stress of less than 2.0. The results can provide a reference to underground powerhouse construction in similar geological conditions.

Stability analysis of surrounding rock mass in underground powerhouse considering damage effect of microfractures

A high-precision microseismic(MS)monitoring system was built to monitor surrounding rock microfractures in the underground powerhouse on the left bank of Shuangjiangkou Hydropower Station.The surrounding rock damage area with spatiotemporal clustering of MS activities was studied for qualitative analysis of the damage mechanism of surrounding rock microfractures,based on the source parameters of MS events.The surrounding rock microfracture scale characterized by the source radius of MS events was considered to establish the constitutive relation.MS information was imported into the model for numerical analysis using fast Lagrangian analysis of continuain 3 dimensions(FLAC^(3D)).The results indicated that the numerical simulation results considering MS damage can better reflect the actual situation of the field.The surrounding rock microfractures mainly showed mixed failure characteristics.Shear failures appeared in localized areas while the fracture scale of sections from K0e33 m to K0e15 m on the vault was large.The deformation increment caused by microfracture damage in the shallow surrounding rock of the top arch accounted for 10%e13%,and the stress decrement in the surrounding rock caused by microfracture damage accounted for about 10%.

Comparative analysis of deformation and failure mechanisms of underground powerhouses on the left and right banks of Baihetan hydropower station

The stability of the surrounding rocks of large underground powerhouses is always emphasized during the construction process,especially in large-scale underground projects under construction,such as the Baihetan hydropower station in China.According to field investigations,numerical simulations and monitoring data analysis,we present a comparative analysis of the deformation and failure characteristics of the surrounding rocks of underground powerhouses on the left and right banks of the Baihetan hydropower station.The failure characteristics and deformation magnitude of the underground powerhouses on the left and right banks are quite different.Under the disadvantageous condition where the maximum principal stress intersects the axis of the powerhouse at a large angle,the left bank underground powerhouse shows prominent stress-controlled failure characteristics such as spalling,slack collapse and concrete cracking.Although the maximum principal stress is in the favorable condition which intersects the right bank powerhouse at a small angle,the relatively high intermediate principal stress with an angle subvertical to the right bank powerhouse plays an essential role in its deformation and failure,indicating that the influence of high intermediate principal stress cannot be ignored.In addition,structural plane-controlled failure and large deformation are also more evident on the right bank due to the extensive distribution of weak structural planes and complex surrounding rock properties.

Effect of Concrete Cracks on Dynamic Characteristics of Powerhouse for Giant-Scale Hydrostation

With the increase of capacity and size of the hydro-generator unit, the spiral case becomes a more super-giant hydraulic structure with very high HD value, where H and D denote water head and maximum intake diameter of spiral case, respectively. Due to the induced lower stiffness by the more giant size and adverse operation conditions, dynamic performances of the powerhouse and the supporting structure for the giant units have become more important and attracted much attention. If the manner of steel spiral case embedded directly in concrete is adopted, on some locations of the concrete surrounding the spiral case, distributed and concentrated cracks will emerge due to high tensile stress. Although the concrete is reinforced well to control the maximum crack width, definitely these cracks will reduce the local and entire stiffness of the powerhouse. Under dynamic loads such as hydraulic forces including water pressure pulsation in flow passage acting on the structure, effect of the cracks on the dynamic characteristics of the local members and entire structure needs to be evaluated. However, research on this subject is few in hydroelectric engineering. In this paper, Three-Gorge Project was taken as an example to evaluate effect of such cracks on natural frequencies and the vibration responses of the powerhouse under hydraulic and earthquake forces in detail. Results show that cracks only reduce the local structural stiffness greatly but have little effect on the entire powerhouse especially the superstructure; vibrations of powerhouse with cracks in concrete surrounding the spiral case are still under the design limits. Results in this paper have been verified by practice of Three-Gorge Project.

Effect of Modeling Range on Structural Analysis for Powerhouse of Hydroelectric Power Plant by FEM

In this paper,three different modeling ranges were selected in the structural analysis for a hydropower house.The analysis was carried out using ABAQUS 6.6.The modeling range has a remarkable effect on finite element method(FEM) calculation result at the middle position of typical cross-sections where the concrete is relatively thin,and at the region close to turbine floor.If the ventilation barrel,floor slabs and columns above turbine floor are excluded from FEM model,the maximum rise difference of pedestal structure increases by about 24% compared with that of the whole model.It is indicated that different modeling ranges indeed affect FEM calculation result,and the structure above turbine floor in the FEM model should be included.

应用系统开发工具PowerHouse

PowerHouse是加拿大Cognos公司的软件产品,提供了一体化的应用系统设计开发工具和运行环境。在中、小型计算机的应用系统开发中,该软件获得了广泛的应用。目前在全世界已有40,000个以上的用户正在使用。特别是该软件的核心产品,第四代语言PowerHouse 4GL,在世界上排名位于前五百名的大公司中就有一百多家公司采用来开发公司内部的应用系统。在众多的应用系统开发工具和第四代语言产品中,PowerHouse之所以具有明显的优势,关键在于该软件的开放性,以及对于应用系统开发中普遍面临的一系列迫切需要解决的问题给出了答案。

Intelligent Layout Method of the Powerhouse for Tank & Armored Vehicles Based on 3-Dimensional Rectangular Packing Theory

Probes into a new and effective method in arranging the powerhouses of tank & armored vehicles. Theory and method of 3-dimensional rectangular packing are adapted to arrange effectively almost all the systems and components in the powerhouse of the vehicle, thus the study can be regarded as an attempt for the theory's engineering applications in the field of tank & armored vehicle design. It is proved that most parts of the solutions attained are reasonable, and some of the solutions are innovative.

Dust Diffusion Simulation in the Third Layer Construction of Underground Powerhouse

Under forced ventilation,the dust diffusion of underground powerhouse construction is investigated using a 3D high Reynolds number k-ε model.The interfacial momentum transfers and the wall roughness in the wall function are considered.Ventilation in the third layer of underground powerhouse of Xiangjiaba hydropower station is used as a case.The geometric structure has a decisive effect on the airflow distribution.It is concluded that the dust concentration decreases gradually with the increase of the ventilation time.However,iso-concentration curves have the same tendency after 1 800 s.The dust concentration meets the ventilation and dust-prevention health standard after 2 300 s.The prediction by the present model is confirmed by the experimental measurement by Nakayama.

The goal: Striving to be a textile powerhouse

This year, 70 years after the founding of New China, the Chinese nation has made a historic leap from standing up to becoming rich and strong. In this great change, the textile industry has achieved all-round and deep-seated development, playing an increasingly important role in serv- ing the overall strategic situation of the country.

新质生产力引领农业强国建设的若干思考

本文从理论逻辑、时代逻辑和现实逻辑三个维度论述了新质生产力引领我国农业强国建设的必要性和必然性。强化农业前沿科技的研究与运用、拓展涉农新业态和培养农业新质人才是发展农业新质生产力的三个核心着力点。传统农业生产领域科技水平的突破、先进要素的引入和集成、农业功能的跨界突破是新质生产力引领农业强国建设的主要实现途径。与此同时,在新质生产力引领我国农业强国建设的进程中,还需要注意处理好发展与底线的关系、提升效率和促进共同富裕的关系、新质生产力和常规生产力的关系,注意避免把新质生产力简单等同于现有生产力的提升、在传统农业业态范畴思考农业新质生产力、“一窝蜂”式的盲目跟风等三个认识和行动上的误区。

加快建设金融强国:政策逻辑、内涵要求与中国改革路径优化

建设金融强国是新时代新阶段中共中央在金融领域的重大创举。从金融大国到金融强国的变迁,是中国经济崛起和金融业高质量发展的必然产物,更是中国特色社会主义事业的积极探索和创新成果。梳理加快建设金融强国的演变逻辑和现实动因发现,加快建设金融强国能够满足中国式现代化进程中的金融政策供给,有效防范和化解金融风险,在全球金融治理体系中建立起更加完善的中国特色金融体系。从中共中央对金融工作的集中统一领导的角度,论证加快建设金融强国的根本遵循,并从“人民性、市场化、国际化、科技化、普惠性、安全性”六大维度,阐释加快建设金融强国的内涵要求。为更好赋能中国式现代化建设,需要深度推动金融业高质量发展并增强保持金融稳定性的能力,应当从打造现代金融市场体系出发,营造良好货币金融环境,全面强化金融监管的前瞻性,防范化解金融风险。

金融强国视域下中国版“监管沙盒”的构建与完善——基于金融科技创新监管试点的应用研究

“监管沙盒”是适应金融科技创新发展的新监管模式。在建设金融强国视域下,系统研究中国版“监管沙盒”的构建与完善,对于深化金融科技创新监管试点,坚定不移走中国特色金融发展之路具有重要意义。中国版“监管沙盒”在借鉴国际经验的基础上,贯彻适应我国金融市场特点、坚持金融服务实体经济等原则,构建了中央与地方配合的顶层设计,探索运用信息公开、产品公示、行业自律等监管机制,并落实了从“入盒”到“出盒”的完整测试流程。中国版“监管沙盒”在金融科技创新监管试点项目中的落地实施,呈现出参与主体多元、监管工具丰富、风险普遍较低等新特征,推动了数字技术与金融场景的深度融合,提升了金融科技服务实体经济能力,但在项目准入、权益保护、持续监管等方面仍有待提升,为此需要完善项目分类遴选与“入盒”标准,打造全流程多元监督闭环,优化“出盒”后的持续监管机制,全面保障金融消费者合法权益,促进金融科技守正创新,助力金融强国建设。

中国金融稳定保障基金最优规模度量和配置研究--基于宏观经济部门非预期损失的分析

金融稳定保障基金是建设金融强国战略背景下维护和实现金融稳定的重要工具。通过编制2008—2020年中国31个省(区、市)金融部门、政府部门、非金融企业部门和家庭部门宏观或有权益资产负债表,运用宏观在险价值方法度量各地区、各部门资产和负债市场价值的非预期损失,估算能充分覆盖重大风险敞口的金融稳定保障基金最优规模和配置比例。研究发现,中国金融稳定保障基金的最优相对规模从大到小依次是:政府部门、非金融企业部门、家庭部门和金融部门。其中,非金融企业部门和家庭部门地区间规模差异显著,东部地区相对规模水平较低,西部地区较高。政府部门作为公共部门具有对其他经济主体的隐性担保责任,最终承担其他部门产生但未抵补的金融风险,是金融稳定的“最后一道防线”。为了更好地防范和化解金融风险,维护金融稳定,金融稳定保障基金应当确定风险适配的目标规模,并实现多层级分部门的有效配置,最终形成全方位、多层次的金融稳定保障基金配置体系。

高水平推进金融强国建设:理论蕴意、现实问题及实现机制——做好金融五篇大文章的视角

高水平推进金融强国建设是当前乃至未来一段时期内我国金融领域工作的重中之重。本文深入阐述做好五篇大文章的重要理论蕴意,客观剖析当前发展面临的主要现实问题,并基于五篇大文章之间的内在逻辑关系分析,提出奋力做好五篇大文章助力高水平金融强国建设的实现机制。研究认为,科技金融是支撑科技强国建设的最有力保障、绿色金融是支撑美丽中国建设的最靓丽底色,普惠金融是支撑共富中国建设的最生动实践,养老金融是支撑和美中国建设的最真实写照,数字金融是支撑数字中国建设的最强大动能。基于此,本文围绕科技强国、美丽中国、共富中国、和美中国、数字中国建设目标,从做深做透科技金融大文章、做精做特绿色金融大文章、做实做细普惠金融大文章、做好做优养老金融大文章,以及做大做强数字金融大文章五个层面提出高水平推进金融强国建设的具体实施机制。

从能源大国到能源强国:国际经验与中国路径

能源是强国之基、推动经济社会高质量和可持续发展的关键支撑。本文梳理了世界主要能源强国或大国的能源建设经验,归纳出能源供应稳定多元、能源消费低碳高效、能源科技创新引领、能源市场开放有序、能源治理体系完备等世界能源强国的普遍特征;在辨识我国能源强国建设的优势与短板的基础上,提出了建设能源强国的中国路径,包括阶段性目标、重点任务和关键举措。研究建议:加大煤炭资源的清洁利用力度,增强煤炭在能源安全中的兜底保障作用;加大油气资源勘探开发和增储上产力度,推进陆相页岩油革命,努力提高油气自给保障能力;推动可再生能源规模化,积极布局氢能等清洁能源,通过多能源协同提高能源安全供应能力、兼顾落实减碳目标。相关举措将有力支撑我国从能源大国到能源强国的顺利转变。

建设农业强国:中国要求、现实挑战与推进路径

强国必先强农,强国建设需以强农建设为基础。立足于粮食安全国际风险、资源禀赋约束、“大国小农”内源困境、农业增值空间小、对外开放水平不高等基本国情农情,中国建设农业强国必须达到供给保障强、科技装备强、经营体系强、产业韧性强、竞争能力强五大要求。通过这些要求的国际比较,中国建设农业强国应提升粮食和重要农产品自给能力,确保多元化食物体系稳产保供;加强农业核心科技研发,提高农业科技成果转化能力;培育新型农业经营主体,促进小农户衔接农业强国建设;拓展涉农产业链,增强产业链与供应链韧性;提高产出效率与国际话语权,培养中国农产品国际竞争力。

乡村振兴战略下中国式畜牧强国建设的路径探析

畜牧业是农业农村发展的支柱产业之一,对保障食品安全有重要影响。乡村振兴战略的推进下,中国式畜牧强国建设已取得一定成效,我国畜牧业转型升级步伐加快,产能持续提升,质量效益和竞争能力持续提高;畜牧产业规模的不断壮大极大地带动了农村发展和农民增收;科技支撑加强,绿色发展进程全面推进,中国式畜牧强国建设取得明显成就。因此,中国式畜牧强国建设需践行绿色发展理念,适应高质量发展要求的具体体现,推进共同富裕的关键路径与核心任务。畜牧业发展需补齐行业短板,全面提升发展质量,坚持扩大内需,有效带动农业农村经济加速增长。应深化科技改革,为畜牧行业绿色转型升级赋能,为驱动中国式畜牧强国建设提供有益参考。