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Method for deducing flow velocity distribution under ice sheet

A technology of flow velocity distribution and ice cover, which is applied in the field of calculation of important parameters, can solve problems such as unmeasurable conditions, complex ice conditions, and high labor intensity of scientific researchers, and achieve the effect of solving complex measurement operations and reducing work intensity

Active Publication Date: 2020-01-17
CHINA INST OF WATER RESOURCES & HYDROPOWER RES
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  • Application Information

AI Technical Summary

Problems solved by technology

Because this kind of measurement is usually carried out in the severe winter season, since it is necessary to dig a hole and perform many measurements, the labor intensity of the researchers is extremely high. On the other hand, in the case of drift ice or ice plugging, the ice surface is complicated. sometimes not measurable at all

Method used

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  • Method for deducing flow velocity distribution under ice sheet
  • Method for deducing flow velocity distribution under ice sheet
  • Method for deducing flow velocity distribution under ice sheet

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0036] 本实施例是一种冰盖下流速分布的推演方法,流程如 figure 1 shown.

[0037] 所述方法的具体步骤如下:

[0038] 步骤1,选择典型河道的测量断面:选择主流河道设置测量断面;对于自然河道则选择在水文站附近,河床形状相对规则,比降适中,水流相对平稳的位置。对于引水渠道则选择在控制闸门和分水口一定距离的位置。测量断面选定后记录测量断面的河床状态,包括:是否为砂石河床、有植被河床、混凝土衬砌河床。根据已有水文资料,将测量断面的水位分为低水位、中水位和高水位。

[0039] 本实施例所述的典型河道是指在水文站附近,即能够经常性的进测量的河河段,或者历史上经常发生冰塞、冰坝的河段。测量断面应当选择在冬季能够形成冰盖1的自然河道,其河床2的横截面形状为中间较深,两侧坡面相对比较对称,且冰盖下流速近似双幂指数分布曲线形状,如 figure 2 shown. 对于引水渠道则由于是人工开挖因此,其河段断面形状比较规则,并且沿途有控制闸门等有人管理设置,测量一般不成问题,因此主要选择在远离闸门和分水口的位置,以避免影响测量。

[0040] 步骤2,将冰期全过程分为流冰期、封冻期和开河期,将封冻期过程分为初封期、稳封期和开河前期:将测量断面的封冻30%、50%、60%、80%作为河道未完全封冻的测量时段;测量断面的初封期测量时间间隔不大于2天,稳封期的测量时间间隔不大于7天,开河前期的测量时间间隔不大于2天;根据冰面具体变化情况或适当的河道断面间距设置,调整封冻期的测量频率。

[0041] 测量时间点选择,当然是选择在冬季水面开始出现流凌直至第二年春天冰面完全融化的整个期间。选择时段除了用年月日时的分段方式外,还要根据冰冻的状态进行分段。本实施例将河道开始出现冰花到河面出现冰盖之前阶段称为流冰期;将河道出现固定冰盖,敞露水面面积小于河道面积20%阶段称为封冻期;将冰盖破裂,冰块开始移动到冰块完全消失阶段称为开河期。将封河期分为3各阶段,冰盖厚度快速增长期为初封期;当冰盖增长一定厚度,冰盖增长缓慢,或者保持不变阶段称为稳定封冻期;随着气温升高,冰盖厚度减小到开河前阶段称为开河前期。对于称为封冻期的完全封冻状态,在实际测量过程中按时日进行测量外,还要根据气候的条件增加测量时段,如在气温骤降等条件下。

[004...

Embodiment 2

[0098]本实施例是实施例一的改进,是实施例一关于率定参数的方式的细化。本实施例所述的率定参数的方式为:遗传法、BP神经网络法、贝叶斯网络法中的一种。

[0099] 遗传法、BP神经网络法、贝叶斯网络法是现代十分常用的概率计算方法,由于现代计算机技术的发展,可以同时使用几种方式同时进行计算,以哪个效果最佳作为取舍。

Embodiment 3

[0101] 本实施例是上述实施例的改进,是上述实施例关于参数率定步骤的细化。本实施例所述的率定参数的步骤中,在率定参数后,根据测量断面建立缩小的实体模型,对各个参数进行试验验证。

[0102] 参数率定后,可以根据被测河段的具体形状建立缩小的实体模型,近似的模拟河道进行参数的实验验证。

[0103] 如建立一个长20m模拟天然河道的宽浅型复式断面可变底坡明渠的模拟河道的试验平台,复式断面河道采用有机玻璃材质加工,以便于观察流态和流速。采用ADV(AcousticDoppler Velocimetr,声学多普勒流速仪)和PIV(Particle Image Velocimetry,粒子图像测速法测量仪)测量流速。

[0104] 冰下流速分布主要取决于流量、冰盖和河床糙率等因素的变化,实验中冰盖糙率取值为3种:0.009、0.017和0.025,实验中模型冰冰盖分别采用有机玻璃板、有机玻璃板上粘贴纱网和聚乙烯泡沫板模拟,分别代表不同封冻期的冰盖糙率。

[0105] 在模拟河道上设置多个测量断面,每个测量断面沿水深方向每隔0.5cm布置一个测点,采用聚乙烯泡沫板模拟冰盖,对水深8cm时的各测点进行流速测量。

[0106] 通过公式(2)数据进行曲线拟合,得到:

[0107] α=0.80,m i =6.3,m b =4.9。

[0108] 已知α、m i 、m b ,采用公式(6)计算得到流量Q=0.056m 3 / s,实测流量为0.055m 3 / s,误差为3.6%。

[0109] 对各个模型测量断面的数值分析,并与实际河流测量断面的参数进行对比两者十分接近,说明本发明所述的流速分别推演方法精确度较高,能够达到准确推演冰盖下流速和流量的 Effect.

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Abstract

The invention relates to a method for deducing the flow velocity distribution under an ice sheet. The method for deducing the flow velocity distribution under the ice sheet comprises the following steps: selecting a measurement section of a typical river channel; selecting time points for recording the measurement section; recording a measurement section status; obtaining flow velocity distribution data; calibrating parameters: taking the flow velocity of each measurement period into the formula; deducing the flow velocity and flow distribution; and accumulating data constantly. According to the method for deducing the flow velocity distribution under the ice sheet, a comprehensive measurement is performed by combining climatic conditions, ice sheet characteristics, and ice freezing stateon a typical river channel, and a number of parameters required for calculations related to the conditions are calibrated through a flow velocity expression. In the freezing period of each subsequentyear, only the climatic conditions, the ice sheet characteristics and the ice freezing state need to be compared to find the corresponding calculation parameters, so that the same flow velocity expression can be used for obtaining the velocity distribution under the ice sheet, and the digging of the ice surface is not required; therefore, the situation that the flow velocity is not consistent withactual flow conditions caused by artificially dividing the sub-ice flow velocity into the ice sheet area and the river bed area is solved.

Description

technical field [0001] 本发明涉及一种冰盖下流速分布的推演方法,是一种防灾减灾水工调控的计算方法,是一种河渠水流控制和调节的重要参数的计算方法。 Background technique [0002] 冬天封冻季节来临时,河道或者调水明渠中会形成冰盖。冰盖的存在明显影响水流流动特性,导致河道阻力增加,过流能力下降,流速分布规律发生变化。对于天然河道无法准确的知道流速和流量将导致无法准确的预计可能出现的冰情灾害,影响防灾减灾的效果。对于调水渠道,不了解水渠中冰盖下的水流流速就无法准确进行冬季结冰条件下调水渠道的安全运行调度,对调水渠道的运行产生不利影响。 [0003] 现有的方式是,在冰封季节,人工在冰面上开凿孔洞,使用流速测量仪器对冰盖下的水流进行直接测量。由于这种测量通常在严冬季节进行,由于需要开凿过个孔洞,并进行许多次的测量,科研人员的劳动强度极大,另一方面在流冰或冰塞的情况下,冰面情况复杂,有时根本无法测量。 Contents of the invention [0004] 为了克服现有技术的问题,本发明提出了一种冰盖下流速分布的推演方法。所的方法通过对冰封期的冰面的观察和测量,率定若干组数据,在之后的冬季用这些数据进行对比,精确推演冰面下的流速,减少了开凿冰面的劳动强度,提高了工作效率。 [0005] 本发明的目的是这样实现的:一种冰盖下流速分布的推演方法,所述方法的步骤如下: [0006] 步骤1,选择典型河道的测量断面:选择主流河道设置测量断面;对于自然河道则选择在水文站附近,河床形状相对规则,比降适中,水流相对平稳的位置;对于引水渠道则选择在控制闸门和分水口一定距离的位置;测量断面选定后记录测量断面的河床状态,包括:是否为砂石河床、有植被河床、混凝土衬砌河床;根据已有水文资料,将测量断面的水位分为低水位、中水位和高水位; [0007] 步骤2,选择记录测量断面的时间点: [0008] 将冰期全过程分为流冰期、封冻期和开河期,将封冻期过程分为初封期、稳封期和开河前期:将测量断面的封冻30%、50%、60%、80%作为河道未完全封冻的测量时段;测量断面的初封期测量时间间隔不大于2天,稳封期的测量时间间隔不大于7天,开河前期的测量时间间隔不大于2天;根据冰面具体变化情况或适当...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01C13/00G01M10/00E02B1/00
CPCE02B1/00G01C13/002G01M10/00
Inventor 王涛郭新蕾付辉路锦枝郭永鑫李甲振纪平邹德昊曾利余弘婧胡志鹏
Owner CHINA INST OF WATER RESOURCES & HYDROPOWER RES