Experimental study on temperature stress calculation and temperature control optimization of concrete based on early age parameters

Temperature control curve is the key to achieving temperature control and crack prevention of high concrete dam during construction,and its rationality depends on the accurate measurement of temperature stress.With the simulation testing machine for the temperature stress,in the present study,we carried out the deformation process tests of concrete under three temperature curves：convex,straight and concave.Besides,we not only measured the early-age elastic modulus,creep parameters and stress process,but also proposed the preferred type.The results show that at early age,higher temperature always leads to greater elastic modulus and smaller creep.However,the traditional indoor experiments have underestimated the elastic modulus and creep development at early age,which makes the calculated value of temperature stress too small,thus increasing the cracking risk.In this study,the stress values of the three curves calculated based on the strain and early-age parameters are in good agreement with the temperature stress measured by the temperature stress testing machine,which verifies the method accuracy.When the temperature changes along the concave curve,the law of stress development is in consistent with that of strength.Under this condition,the stress fluctuation is small and the crack prevention safety of the concave type is higher,so the concave type is better.The test results provide a reliable basis and support for temperature control curve design and optimization of concrete dams.     

杨房沟水电站建设质量智慧管理系统的研发及应用

为提高工程管理效率、控制工程质量、减少人为因素对工程质量的影响,利用信息化、数字化、自动控制等技术对施工过程中的信息、混凝土温度、混凝土振捣、灌浆等环节进行智能监控和管理。为此,杨房沟水电站依托设计施工BIM管理系统的质量管理功能模块,以及由BIM系统集成的智能温控、智能振捣、智能灌浆、全过程影像采集系统,研发形成了大坝智能建造环境下的质量智慧管理系统。通过实现施工质量信息“实时采集-实时分析-决策反馈”的动态质量管理,解决了EPC建设模式以及传统大坝质量管理存在的施工质量控制、信息收集、分析、决策等方面的问题,提高了管理效率和管理质量,取得了较好的管理成效。     

沥青混凝土心墙土石坝水力劈裂计算分析

分析了土石坝水力劈裂原理,针对新疆吐鲁番二塘沟沥青混凝土心墙土石坝,选取河床部位最大断面为典型断面,采用有限元法对其进行水力劈裂计算分析,得出:该土石坝心墙任一高程处的中主应力都小于竖向应力,且中主应力和竖向应力都大于水压力。因此,该坝的心墙不会发生水力劈裂。     

Sediment storage and shallow groundwater response to beaver dam analogues in the Colorado Front Range,USA

Enthusiasm for using beaver dam analogues (BDAs) to restore incised channels and riparian corridors has been increasing. BDAs are expected to create a similar channel response to natural beaver dams by causing channel bed aggradation and overbank flow, which subsequently raise water tables and support vegetation growth. However, lack of funding for monitoring projects post‐restoration has limited research on whether BDAs actually cause expected channel change in the Front Range and elsewhere. Geomorphic and hydrologic response to BDAs was monitored in two watersheds 1 year post‐restoration. BDAs were studied at Fish Creek, a steep mountainous catchment, and Campbell Creek, a lower gradient piedmont catchment from May to October 2018. At each restoration site, the upstream‐ and downstream‐most BDAs were chosen for intensive study in comparison with unrestored reference reaches. Monitoring focused on quantifying sediment volumes in BDA ponds and recording changes to stream stage and riparian groundwater. Despite differences in physical basin characteristics, BDA pools at both sites stored similar volumes of sediment and stored more sediment than reference pools. Sediment storage is positively correlated to BDA height and pool surface area. However, BDAs did not have a significant influence on shallow groundwater. The lack of groundwater response proximal to BDAs could indicate that local watershed factors have a stronger influence on groundwater response than restoration design 1 year post‐restoration. Systematic, long‐term studies of channel and floodplain response to BDAs are needed to better understand how BDAs will influence geomorphology and hydrology.     

基于应力-渗流-损伤耦合模型的重力坝三维水力劈裂数值模拟

裂缝的高压水力劈裂是混凝土高坝安全评估的重要部分。目前,重力坝水力劈裂的数值模拟绝大多数是二维的,对于坝体上游面经常出现的竖直裂缝的三维水力劈裂的数值研究几乎为零。本文提出一种应力-渗流-损伤耦合模型,用于混凝土重力坝三维水力劈裂的模拟。采用该耦合模型,模拟了一个内置裂缝的圆柱体试件的水力劈裂,数值结果与试验结果吻合很好,验证了所提耦合模型的合理性。在此基础上,采用该耦合模型,进行了国内某混凝土重力坝三维水力劈裂的模拟,数值模拟得到的损伤区域与设计院根据安全监测实测结果得到的范围基本吻合。研究结果表明:本文耦合模型可以方便、有效地进行重力坝三维水力劈裂的模拟,评估表面裂缝的危险程度。     

江垭水电站碾压混凝土重力坝的温度应力分析

为研究温度荷载对江垭水电站碾压混凝土重力坝的影响,以其非溢流坝段为研究对象,建立有限元模型,根据江垭水电站的水温、气温、坝体温度、地基温度等监测资料,计算分析了大坝运行期的温度场,研究了大坝在温度场影响下的应力变化规律.研究结果表明:温度荷载对大坝运行有较大影响,但是大坝仍满足规范设计要求;夏季持续高温时,应避免大坝在高水位下运行;冬季持续低温时,应避免大坝在低水位下运行.     

小湾拱坝应力监测资料分析

小湾水电站以发电为主,兼顾防洪、灌溉和库区水运等.坝址处河谷基本对称,河谷深切呈"V"字型.为深入研究小湾拱坝坝体的动、静工作性态,对小湾拱坝坝体进行应力监测;根据应力监测资料进行徐变应力计算,得到实际应力,然后利用作图、特征值统计等定性时空分析方法推断出大坝应力无明显异常;通过分析统计结果以及压应力变量分离模型得到了应力的统计模型.     

Methodology for estimating probability of dynamical system’s failure for concrete gravity dam简

Methodology for the reliability analysis of hydraulic gravity dam is the key technology in current hydropower construction.Reliability analysis for the dynamical dam safety should be divided into two phases：failure mode identification and the calculation of the failure probability.Both of them are studied based on the mathematical statistics and structure reliability theory considering two kinds of uncertainty characters（earthquake variability and material randomness）.Firstly,failure mode identification method is established based on the dynamical limit state system and verified through example of Koyna Dam so that the statistical law of progressive failure process in dam body are revealed; Secondly,for the calculation of the failure probability,mathematical model and formula are established according to the characteristics of gravity dam,which include three levels,that is element failure,path failure and system failure.A case study is presented to show the practical application of theoretical method and results of these methods.     

贵州省白马山水库混凝土砌石拱坝优化设计

贵州省白马山水库大坝是一座混凝土砌毛石重力单曲拱坝,最大坝高48 m,采用ADAO拱坝分析与优化软件,对坝体结构、应力变形、坝肩稳定性等进行了分析。调整了设计方案,使坝体设计方案满足SL25-2006和SL282-2003等技术规范要求。     

300MW火电厂灰场坝体变形观测设计方案

文章通过对某发电厂贮灰场坝体变形观测,介绍了变形观测基准网和监测网的布网、施测细则、质量保证措施、工艺流程和方案设计情况.