冬季输水梯形渠道冻胀时水力因素对刚性衬砌层内力影响研究

对于冬季输水渠道,在其基土冻胀作用时边坡混凝土板力学模型得到实践工程检验的基础之上,又以实际工程渠道为参数,理论分析了在特定冻胀力作用类型及计算方法的条件下,其渠道坡角、水深和边坡混凝土板厚度的变化对边坡混凝土板内力的影响规律。结果表明:冬季输水渠道边坡板在冬季渠基土冻胀的过程中有沿坡面整体上移的趋势;在渠基土边坡整体稳定的前提条件下,增大渠道坡角、减小渠底宽、提高渠内水位可大大减少渠道冻胀作用时边坡板的内力,降低渠道冻胀破坏的机率;通过增加边坡板的厚度来提高渠道抗冻胀破坏能力是不可取的。该成果为季节冻土区冬季无冰盖输水渠道的抗冻胀破坏设计指出了设计新思路。根据设计流量,设计并调整渠道水力参数,尽可能使渠内水深提高,不仅降低渠道冻胀破坏的机率,还可以减少渠道用地面积和土方工程量。     

衬砌渠道抗冻胀分析

通过对衬砌渠道进行实例计算,阐述了抗冻胀计算的规定、控制点的确定、需计算的内容,并对计算结果进行了分类和判断。     

长距离明渠输水渠道变形分析

由于长距离明渠输水工程存在工程条件多样化、质量标准要求高等工程特点,因而解决渠道变形问题是维持输水工程正常运转的关键问题。为了发挥输水工程的各方面效益,对长距离明渠输水工程中渠道变形问题进行深入分析,并提出相应的处理建议。     

梯形渠道混凝土衬砌冻胀破坏的力学模型探讨

通过对梯形渠道混凝土衬砌冻胀破坏特征的分析及总结前人的相关研究成果,提出合理的简化和假设,并在此基础上建立了一种梯形渠道混凝土衬砌冻胀破坏的力学模型。通过该模型可计算渠道坡板和底板的各控制内力及应力,并估计可能发生胀裂的位置,提出了对渠坡衬砌板所受法向冻结力的计算方法。     

砂卵石换填对渠道衬砌抗冻胀效果影响的试验研究

渠道抗冻胀破坏设计具有重要的理论意义和工程应用价值.此次研究通过某灌区支渠现场试验,探讨了砂卵石换填对渠道衬砌抗冻胀效果的影响.结果显示,砂卵石基土换填可以对冻胀量产生明显的控制作用,且砂卵石的粒径在6～8 cm时的效果最佳,建议在工程设计时选用.     

大U形混凝土衬砌渠道冻胀破坏的力学模型探讨

通过对U形混凝土衬砌渠道冻胀破坏机理的分析,提出了U形混凝土衬砌渠道冻胀破坏的力学模型,并解出了渠坡直线段和圆弧段控制内力及最大拉应力,结合混凝土板抗裂条件给出了冻胀力、胀裂部位、冻胀抗裂衬砌板厚度及抗冻胀破坏验算的一系列计算方法.     

西北地区衬砌渠道抗冻胀设计讨论

针对西北地区衬砌渠道冻胀破坏的原因,分析了典型破坏的几种形式,从设计角度出发,提出了防止冻胀的设计应对措施,对西北地区衬砌渠道的设计具有一定借鉴意义。     

张掖大满干渠衬砌冻胀破坏原因分析及改造设计

1概况张掖大满干渠属东西走向，于1967年建成，经过20多年运行。渠道衬砌因冻胀破坏的占40％，此外因工程自然老化和其它原因破坏的占20％，因而影响了渠道正常输水运行。另一方面，依据已审批的黑河干流“规划”，大满干渠控制的灌溉面积有所增加，渠道设计流量由16．7m3／s，增大为18m3／s（加大流量21m3／s），为此渠道需进行改建。2自然条件及地质条件2．1气候大满干渠地处黑河中游，气候寒冷，多年平均气温在7℃左右，最高气温38℃，最低气温-28℃，日温差最高达31℃。11月中旬开始封冻至次年3月解冻，冻结期约4个月、冻士深度109～123…     

灌区小型U形渠冻胀破坏研究与优化

水利灌渠工程一般规模巨大,其结构受到温度、洪水、地震等因素影响并出现不同程度的损坏。灌渠防渗漏衬砌是有效阻止水分流失的方法,从大量防渗漏工程来看,U形混凝土衬砌性能最佳。其具有水力条件好、占地面积少、抗冻能力强等优点。但是西北地区冬季温度较低,U形混凝土衬砌还是会发生冻胀破坏,严重影响灌渠的使用性能。从国内外研究现状出发,指出渠道冻胀破坏研究存在的问题,并以整体式U形渠道混凝土衬砌结构为研究对象,研究了其冻胀破坏力学模型,并对力学模型进行求解分析。希望为今后整体式形混凝土衬砌渠道在西北地区的推广奠定基础。     

渠道冻胀处理方式的选择

近年来,通过对喀什地区渠道设计、实施、运行效果的调查,经分析研究得知,渠道的冻胀破坏是由土壤中的水、土体颗粒物理性质和负温所致,大多发生在灌区的中下部。渠道防冻胀处理可通过改变渠道结构形式、改变渠基土体的基本结构、使用新型建筑材料等方法来实现。对渠道防冻胀处理方式的选择,关系到渠道的造价和施工的难易,在今后的渠道设计与施工中应不断地总结经验,进一步完善新型材料的防冻理论和实际运用经验,为新型防冻材料的推广应用及渠道冻胀处理方式的选择提供参考。     

浅谈水库设计洪水复核应注意的几个问题

水库洪水复核应遵循“多种方法、多种途径、综合分析、合理选用”的 1 6字方针 ,同时还应注意并重视集雨面积、库容曲线、历史洪水、设计暴雨、计算方法选择等问题的正确性 ,为此以东敢水库设计洪水复核的例子 ,说明要注意以上几个问题的必要性和可行性。     

Swimming behavior of crucian carp in an open channel with sudden expansion

The sudden‐expansion effect created by natural and man‐made structures such as unsubmerged boulders, spur dikes, and culvert structures is common in open channels. Migratory fishes may use the heterogeneous flow generated by sudden expansion to their benefit, to select habitats for balancing energy expenditure or for maximizing predation opportunities. This study explores the swimming behavior of three size classes of crucian carp in response to hydrodynamic characteristics in an experimental open channel with sudden expansion. The flow field was characterized using particle image velocimetry (PIV) measurements and featured a recirculation zone in the vicinity of the expansion. Based on the classification of the swimming trajectory, four specific swimming behaviours (SSBs) were utilized by crucian carp during migration. With increasing flow velocity, fish spent more time in the recirculation zone. Residence time in the recirculation zone was inversely correlated with fish body length. Due to the advantage in providing shelter from challenging heterogeneous hydraulic conditions, the recirculation zone was preferred by crucian carp, especially the smaller ones, indicating the importance of energy conservation in habitat occupation. These findings confirm that the recirculation zone generated by sudden expansion may be beneficial to the upstream passage of fish and in habitat restoration.     

新疆灌区明渠量测水现状与对策初探

针对目前新疆灌区明渠水量监测现状进行了调查分析，结果表明:新疆灌区现行的水量 检测方法和现有设备存在受人为因素影响大、仪器安装位置不合理且参数设置不正确等问题，故 监测任务繁重，计算精度有限。为此建议:应引进适合本地区的先进量测水监测技术与设备、对 相关专业人员进行培训、定期校核水位一流量关系、及时维护监测段渠道等，从而保证监测数据 的准确性和可靠性。     

乡镇供水工程设计中应注意的若干问题

乡镇供水作为水利开发建设中的一个新领域，设计工作是龙头，有许多技术问题需要研究和探索，阐述了乡镇供水工程设计应注意的若干问题，并对设计中存在的一些具体问题进行了分析和探讨。     

水电站大口径亚刚体不锈钢波纹管伸缩节的现场制作

介绍了新疆某水电站DN6200mm亚刚体不锈钢波纹管伸缩节厚壁件的卷制、厚壁件现场制作的拼装工艺和焊接工艺，制订了现场拼焊的质量控制要点和检测标准。     

Self-aeration of open channel flow

It is suggested that the cause of self-aeration in open-channel flow occurs when the turbulent normal stress exceeds the gravimetric pressure. A criterion for the start of self-aeration is established on this basis. A computational four-layer model of an aerated flow is proposed. It is also proposed that the equation of turbulent diffusion be used to calculate the distribution of air concentration along the normal to the bottom. Results are compared with experimental distributions of concentrations, and a satisfactory relationship is obtained.     

三峡工程导流明渠截流工程实施

三峡工程导流明渠截流已于2002年11月6日顺利合龙，截流前的施工准备工作非常充分，包括备料，水陆交通、设备等，为加快截流进度，减少抛填料流失，龙口段均提前设置了加糙拦石坎，并进行平抛垫底；在截流时间决定提前后，又新增了一些必须措施，如赶制钢筋石笼，特重混凝土四面体等，龙口段进占施工过程中，上下游戗堤统一协调按科学调度组织进占，十分有效地降低了综合难度，真正实现了科学化，信息化截流。     

River bed evolution due to channel expansion: general behaviour and application to a case study (Kugart River,Kyrgyz Republic)

We study the effect of spatial variations of river width on bed aggradation and degradation processes, making use of a one‐dimensional numerical model of channel morphodynamics. We refer to a peculiar case, the downstream reach of the Kugart River (Kyrgyzstan). The river has been partly channelized in the recent past with the aim of reducing the flooding risk for the surrounding villages; the consequent reduction of channel width in some reaches was also expected to improve channel conveyance with respect to the high sediment load produced in the upper river basin. The resulting longitudinal sequence of relatively sharp channel expansions and contractions has, however, triggered rapid siltation rates, especially in the narrowest reaches. This motivated the application of a 1‐D numerical model of river morphodynamics. Abrupt channel expansions are found to be the main driving forces for aggrading processes, which may extend for long distances from where they are generated. In order to obtain a thorough understanding of the morphodynamics of channel expansions, we first apply the model to simple test cases. This allows us to characterize the basic features of the problem and the dependence of bed evolution on the upstream Froude number Fr and on the expansion ratio r_b, which are the most relevant controlling parameters. We invariably find that deposition occurs in expansion regions with bed aggradation observed both upstream and downstream. The deposition prism progressively increases its height and lengthens both in the upstream and downstream directions. The deposition process is particularly intense, in terms of deposition prism height, in super‐critical conditions. Moreover, it is found that higher values of Fr strongly reduce the time scale of morphological processes and faster deposition rates are further facilitated by abrupt expansions. The present outcomes are relevant for assessing the expected altimetric response of river bed to the implementation of localized channelization works and to local river widening, a practise which is increasingly being employed within river restoration projects, with the aim of enhancing habitat diversity. Copyright © 2008 John Wiley & Sons, Ltd.