CN117456689A - Overflow water level early warning method for moraine lake burst and application thereof - Google Patents
Overflow water level early warning method for moraine lake burst and application thereof Download PDFInfo
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Abstract
The invention discloses an overflow water level early warning method for ice lake burst, which belongs to the technical field of hydraulic engineering and is characterized by comprising the following steps: a. survey and measure overflow channel of tillite lake, measure average medium diameter particle diameter D of coarse granule armor layer of overflow channel, measure gentle slope section slope alpha and abrupt slope section slope beta of overflow channel, measure the surface difference of height h of existing water level of tillite lake at overflow mouth entrance section and coarse granule armor layer 0 The method comprises the steps of carrying out a first treatment on the surface of the b. Determining a failure mode of the overflow channel in which the coarse-grain armor layer is started, and determining the burst critical water level H of the moraine lake C The method comprises the steps of carrying out a first treatment on the surface of the c. Building water level monitoring points around the overflow port, measuring the existing water level of the tillite lake as a basic water level, and carrying out monitoring and early warning according to the existing water level of the tillite lake; d. and (5) dividing the early warning grade. The invention comprehensively considers the influence factors of the moraine lake burst critical overflow water depth, and the calculated result is more in line with the actual situation, thereby greatly improving the early warningAccuracy and better applicability.
Description
Technical Field
The invention relates to the technical field of hydraulic engineering, in particular to an overflow water level early warning method for moraine lake burst and application thereof.
Background
Moraine lake break is a natural phenomenon that occurs in the distribution area of mountain glaciers. The main causative type of the moraine lake burst is the overflow burst caused by ice landslide or ice collapse into the lake. When the water level of the ice slides or is in the lake to rise to form overflow in the overflow channel on the tillite dike, and the overflow water level is higher, the water flow carries coarse stone which erodes the overflow channel, and then erode the mixed sediment deposited under the rough stone, so that the overflow channel is eroded and undercut, and then expands to two sides, and finally the overflow channel is completely eroded, so that the moraine lake is broken. In addition, landslide or collapse causes a large amount of sediment to enter the tillite lake, heavy rain or ice and snow melt, and the upstream ice lake breaks, and the water level of the tillite lake rises to finally cause the tillite lake to break. Therefore, the research on the critical water level condition of the overflow burst of the tillite lake is the basis for predicting and forecasting the burst disaster of the tillite lake. The calculation and research of critical overflow water depth for the moraine lake burst at home and abroad is mainly based on the assumption that the rising water depth is equal to the burst water depth, namely, the original moraine lake water level is zero, which obviously does not accord with the reality. Or the water depth of the moraine lake is adopted to replace overflow water depth when calculating the burst flood (the two water depths are different by about 1 order of magnitude), and the calculation result has larger error. (Jiang Zhongxin, cui Peng, jiang Liangwei, tillite lake overflow type break critical hydrologic conditions, journal of railway engineering, 2004, 84 (4): 21-26.). The ice is produced by the ice-breaking, the induction factor of the break of the lake is that the temperature rises, the ice-breaking occurs in the glacier at the rear edge of the moraine lake, the bulk ice enters the moraine lake, the water level rises suddenly, the overflow water level rises greatly to erode the sediment at the overflow port of the morchel, and the ice-levee breaks. The abrupt rise of the water level is a direct influence condition, so that the sudden change of the water level can be monitored to early warn the burst of the tillus lake. Factors affecting the water level in the tillite lake are numerous and can be generally categorized as: ice, dyke top thickness, ice, rock-box back Shui Po gradient, rock-box lake area etc. (institute of mountain disaster and environment, institute of traffic science and technology, university of tibetan, 1999, 79-89.) but after the water level suddenly rises, the water flow overflowing outwards at the overflow port of the ice dyke can cause rising water level to fall back, if the fall back is faster, the rock-box top thickness of the ice dyke is not completely eroded yet, and when the water level falls back to the water level which can not erode sediment, the rock-box lake will not break. Therefore, the critical water level of the moraine lake burst is related to factors such as ice, dam top thickness, ice border wall overflow width, sediment particle size of the border wall overflow, moraine lake area, moraine lake surface morphology (average width and aspect ratio), moraine lake shore slope average gradient, and the like, which must be considered to obtain reliable moraine lake burst conditions.
The Chinese patent literature with publication number CN107749144A and publication date 2018, 03 and 02 discloses an overflow water level early warning method for ice lake burst, which comprises the following steps: a. investigation and measurement of ice front dam top thickness T, break opening width b and average ice lake width w 0 The length-width ratio c of the ice lake, the average slope beta of the bank slope of the ice lake before burst and the characteristic particle diameter d of starting sediment; b. calculating to obtain critical overflow depth H of ice lake burst; c. the water level of the ice lake above the overflow port suddenly rises for more than 30s, and when H Cr Less than 0.6H, and the burst occurrence probability of the ice lake is very small; when H is more than or equal to 0.6H Cr Less than 0.8H, and the burst occurrence probability of the ice lake is small; when H is more than or equal to 0.8H Cr < H, the burst occurrence probability of the ice lake is moderate; when H is Cr And the probability of occurrence of burst of the ice lake is high.
According to the overflow water level early warning method for the burst of the ice chest disclosed in the patent document, a pre-warning and forecasting model for the burst of the ice chest is established by researching the critical water depth condition of the burst of the ice chest; the method comprehensively considers the width of the breaking opening of the tillite lake, the average width and the length-width ratio of the tillite lake, the starting particle size on the tillite dike and other topography and characteristic parameters, forecast the breaking of the tillite lake in a quantitative mode, and has strong applicability. However, the method mainly considers the characteristic parameters of the moraine dike, such as the characteristic particle diameter of the coarse particles on the surface of the moraine dike as sediment starting, the average width, the length-width ratio and other parameters of the moraine lake, and also considers the width and other parameters of an overflow port, thereby being an ice lake burst early warning method comprehensively considering the factors such as the continuous erosion time after the water level rises. However, the key to the burst of the tillite lake is not the tillite dike, but the overflow channel on the tillite dike, and the coarse particle armor layer of the overflow channel, i.e. the coarse stone block on the surface, has two conditions of starting and breaking: firstly, coarse particles are started by water flow at the gradient turning points of the overflow channel, namely the turning points of the gentle slope and the steep slope, so that the coarse particle armor layer of the overflow channel can generate chain reaction, and peripheral coarse particles are gradually started; and secondly, under the condition of a large gradient, the steep slope armor layer of the overflow channel is started integrally or called slope instability. Both conditions can cause the armor layer to be damaged, the overflow port of the moraine lake protected by coarse particles of the armor layer is lost, the overflow port is further eroded by water flow, the overflow port is eroded downwards and around, and finally the moraine lake is broken. The duration of the water level rise in the moraine lake is therefore not critical, it being important that the higher water level be able to initiate coarse armor layer particles at a first time. The erosion start of coarse particles on the armor layer at the overflow port is a key factor for causing the burst of the tillite lake, and the overflow water level of the tillite lake at the overflow port is a key condition for stimulating the burst of the tillite lake, and the patent document does not consider the burst actual condition of the tillite lake and influences the early warning accuracy.
Disclosure of Invention
In order to overcome the defects of the prior art, the overflow water level early warning method for the burst of the tillus and the application thereof are provided, the influence factors of the critical overflow water depth of the burst of the tillus are comprehensively considered, the calculated result is more in line with the actual situation, the early warning accuracy is greatly improved, and the method has better applicability.
The invention is realized by the following technical scheme:
an overflow water level early warning method for ice lake burst is characterized by comprising the following steps:
a. survey and measure overflow channel of tillite lake, measure average medium diameter particle diameter D of coarse granule armor layer of overflow channel, measure gentle slope section slope alpha and abrupt slope section slope beta of overflow channel, measure the surface difference of height h of existing water level of tillite lake at overflow mouth entrance section and coarse granule armor layer 0 If the existing water level of the tillite lake is lower than the surface of the coarse-grain armor layer, h 0 If the existing water level of the tillite lake is higher than the surface of the coarse-grain armor layer, h 0 Negative;
b. according to the steepness of the overflow channelDetermining the damage mode of the coarse-grain armor layer of the overflow channel when the coarse-grain armor layer is started, and determining the burst critical water level H of the fringed lake C ；
c. Building water level monitoring points around the overflow port, measuring the existing water level of the tillite lake, and carrying out monitoring and early warning according to the existing water level of the tillite lake as a basic water level;
d. dividing early warning grades, and when the monitoring water level H of the tillite lake is less than 0.75H C The occurrence probability of the moraine lake burst is very small, and a green safety signal is sent out; when the water level H of the tillite lake is more than or equal to H C The duration is less than 30s, the occurrence probability of the moraine lake burst is small, and a yellow early warning signal is sent; when the water level H monitored by the tillite lake is more than or equal to 0.75H C The duration is longer than 30s, and an orange early warning signal is sent out in the occurrence probability of the moraine lake burst; when the water level H of the tillite lake is more than or equal to H C And the duration is longer than 30s, the occurrence probability of the moraine lake burst is high, and a red early warning signal is sent out.
In the step b, when the gradient beta of the abrupt slope section is more than or equal to 25 degrees, the damage mode of the started coarse-grain armor layer is the integral starting, and the critical water level H is determined by the moraine lake C Calculated by formula 1;
H C ＝h 0 +0.75D+1
When the gradient beta of the abrupt slope section is less than 25 DEG, the damage mode of the coarse-grain armor layer started is single starting, and the critical water level H is determined by the moraine lake C Calculated by formula 2;
H C ＝h 0 ++ (2.45-0.1K) D2;
wherein H is C Determining critical water level for tillite lake; d is the average medium diameter particle diameter of the coarse-grain armor layer of the overflow channel; beta is the gradient of the steep slope section, K is the gradient difference between the gradient of the steep slope section and the gradient of the gentle slope section of the overflow channel, K is less than or equal to 20, and when K is more than 20, K is 20; h is a 0 The existing water level of the tillite lake is the surface height difference between the inlet section of the overflow port and the coarse-grain armor layer.
In the step d, the monitoring water level H of the tillite lake refers to comparing the water level after the water level is measured at the moment.
The method is suitable for early warning of the burst of the tillite lake caused by the rising of the water level of the tillite lake.
The invention is suitable for the pre-warning of the burst of the water level of the tillus lake caused by the fact that the glacier is subjected to ice collapse, landslide or collapse and enters the tillus lake.
Furthermore, the invention is suitable for the early warning of the burst of the tillite lake caused by rising of the water level of the tillite lake due to rainfall or ice and snow melting.
Furthermore, the invention is suitable for the early warning of the burst of the moraine lake, which is caused by the burst of the upper stream moraine to cause the rise of the water level of the moraine lake.
The basic principle of the invention is as follows:
the overflow channel is arranged on the moraine dike of the moraine lake, and generally in rainy season or summer, the water flow of the ice and snow melting enters the moraine lake, and then enters the overflow channel through the overflow port to flow to the downstream. The overflow channel is covered on the surface by coarse stone, and coarse-grain armor layers are formed to protect mixed grains below the overflow channel. When the overflow water level is not high, the water flow cannot erode coarse particles for carrying the overflow channel, the overflow channel is protected by coarse particle armor layers, erosion cannot occur, the moraine dyke cannot be broken, and the moraine lake is in a stable state. When the water level of the tillite lake rises, the overflow water level at the overflow port also rises, and the water level of the water flow in the overflow channel also rises, two situations can happen at the moment:
firstly, under the conditions of large gradient, 25 degrees and above, the high water level causes the whole instability of the coarse-grain armor layer, and the coarse-grain armor layer moves downstream together;
when the gradient of the steep slope section of the overflow channel is below 25 ℃, the coarse grain armor layer cannot be integrally unstable, but at the turning point of the steep slope section and the gentle slope section, coarse grains are exposed most at the turning point due to abrupt change of gradient, and under the condition of higher water level, individual coarse grains are started by water flow because the grain size is relatively smaller or are excessively exposed, and at the moment, the balance of the coarse grains around the grains is broken, and coarse grains at the upstream and downstream and at two sides of the coarse grains are started to move to the downstream along with the break; the overflow channel protected by the coarse-grain armor layer is lost, so that the overflow channel is rapidly eroded, and is eroded to two sides downwards, thereby causing the collapse of the iceland lake.
The basic principle of the invention is that the water level of the water level rise of the tillite lake exceeds the critical water level of the overflow port, and a higher water level is formed in the overflow channel, so that the tillite lake is broken. Based on the mechanism research, the early warning method and the judgment standard are provided through a large number of researches and accurate deductions and calculation.
The beneficial effects of the invention are mainly shown in the following aspects:
1. according to the method, the influence factors of the critical overflow depth of the moraine lake are comprehensively considered, the calculated result is more in line with the actual situation, the early warning accuracy is greatly improved, and the method has better applicability.
2. The direct cause of the burst of the moraine lake is that the water level of the moraine lake exceeds the critical water level for starting the erosion overflow channel, and the indirect cause is that the temperature rises to melt snow or rainfall; ice collapse occurs in a relatively large volume; the larger ice disintegration body enters the tillite lake to cause more water level rising; the landslide or collapse with larger volume enters the ice lake to cause more water level rise; the ice lake upstream of the tillite lake breaks up, so that a large amount of water enters the tillite lake, and the water level rises; according to the method, the factor of the rising water level of the tillus lake, which directly causes the collapse of the tillus lake, is more directly considered as the early warning index, and the uncertainty of other indirect influencing factors is avoided, so that the early warning accuracy is higher, and the adaptability is stronger.
3. According to the invention, the different mechanisms of rising and starting the coarse-grain armor layer which erodes the overflow channel on the water level of the tillite lake are considered, and the mechanism of starting the whole grains of the coarse-grain armor layer is utilized, so that the proper water level breaking condition is given under the condition of large gradient of the steep slope section of the overflow channel, and the applicability is very strong.
4. According to the invention, different mechanisms of rising and starting to erode the coarse-grain armor layer of the overflow channel on the water level of the moraine lake are considered, and the mechanism of starting single grains of the coarse-grain armor layer is utilized, so that starting can be formed below 25 degrees of the abrupt slope section and the gentle slope section of the overflow channel at the turning point of the abrupt slope section, proper water level breaking conditions are provided, and the applicability is enhanced.
5. The breaking mechanism is that the water level of the starting erosion position of the coarse particle armor layer of the overflow channel rises, specifically, the water level of the turning point of the steep slope section or the steep slope section and the gentle slope section rises, but the water level monitoring is very difficult to set up at the position, the monitored water level fluctuates greatly due to the influence of the boulder, the correct monitored water level is difficult to be given, the inlet water level of the overflow channel is adopted during monitoring, and the monitoring and early warning can be carried out in combination with the water level of the current ice-tills and lakes, so that the breaking of the ice-tills and lakes can be well early warned, and the method has high applicability.
6. The method is suitable for early warning of the burst of the tillite lake caused by the rising of the water level of the tillite lake; the method is suitable for early warning of the collapse of the tillite lake caused by the water level rising of the tillite lake due to the fact that the glacier is subjected to ice collapse, landslide or collapse into the tillite lake; the method is suitable for early warning of the burst of the tillite lake caused by rising of the water level of the tillite lake due to rainfall or ice and snow melting; the method is suitable for early warning of the burst of the moraine lake caused by the burst of the upstream moraine lake, and has wide applicability.
Drawings
The invention will be further described in detail with reference to the drawings and detailed description, wherein:
fig. 1 is a graph showing the relationship between the average median diameter D of coarse-grain armor layers of overflow channels and the monitoring water level H of the moraine lake.
Detailed Description
Example 1
An overflow water level early warning method for ice lake burst comprises the following steps:
a. survey and measure overflow channel of tillite lake, measure average medium diameter particle diameter D of coarse granule armor layer of overflow channel, measure gentle slope section slope alpha and abrupt slope section slope beta of overflow channel, measure the surface difference of height h of existing water level of tillite lake at overflow mouth entrance section and coarse granule armor layer 0 If the existing water level of the tillite lake is lower than the surface of the coarse-grain armor layer, h 0 If the existing water level of the tillite lake is higher than the surface of the coarse-grain armor layer, h 0 Negative;
b. according to the gradient beta of the steep slope section of the overflow channel, determining the damage mode of the started coarse-grain armor layer of the overflow channel, and determining the critical water level H of the burst of the ice, the lake C ；
c. Building water level monitoring points around the overflow port, measuring the existing water level of the tillite lake, and carrying out monitoring and early warning according to the existing water level of the tillite lake as a basic water level;
d. dividing early warning grades, and when the monitoring water level H of the tillite lake is less than 0.75H C The occurrence probability of the moraine lake burst is very small, and a green safety signal is sent out; when the water level H of the tillite lake is more than or equal to H C The duration is less than 30s, the occurrence probability of the moraine lake burst is small, and a yellow early warning signal is sent; when the water level H monitored by the tillite lake is more than or equal to 0.75H C The duration is longer than 30s, and an orange early warning signal is sent out in the occurrence probability of the moraine lake burst; when the water level H of the tillite lake is more than or equal to H C And the duration is longer than 30s, the occurrence probability of the moraine lake burst is high, and a red early warning signal is sent out.
The embodiment is the most basic implementation mode, the influence factors of the critical overflow water depth of the moraine lake are comprehensively considered, the calculated result is more in line with the actual situation, the early warning accuracy is greatly improved, and the method has better applicability.
Example 2
An overflow water level early warning method for ice lake burst comprises the following steps:
a. survey and measure overflow channel of tillite lake, measure average medium diameter particle diameter D of coarse granule armor layer of overflow channel, measure gentle slope section slope alpha and abrupt slope section slope beta of overflow channel, measure the surface difference of height h of existing water level of tillite lake at overflow mouth entrance section and coarse granule armor layer 0 If the existing water level of the tillite lake is lower than the surface of the coarse-grain armor layer, h 0 If the existing water level of the tillite lake is higher than the surface of the coarse-grain armor layer, h 0 Negative;
b. according to the gradient beta of the steep slope section of the overflow channel, determining the damage mode of the started coarse-grain armor layer of the overflow channel, and determining the critical water level H of the burst of the ice, the lake C ；
c. Building water level monitoring points around the overflow port, measuring the existing water level of the tillite lake, and carrying out monitoring and early warning according to the existing water level of the tillite lake as a basic water level;
d. dividing early warning grades, and when the monitoring water level H of the tillite lake is less than 0.75H C Tillite (tillite)The occurrence probability of the lake burst is very small, and a green safety signal is sent out; when the water level H of the tillite lake is more than or equal to H C The duration is less than 30s, the occurrence probability of the moraine lake burst is small, and a yellow early warning signal is sent; when the water level H monitored by the tillite lake is more than or equal to 0.75H C The duration is longer than 30s, and an orange early warning signal is sent out in the occurrence probability of the moraine lake burst; when the water level H of the tillite lake is more than or equal to H C And the duration is longer than 30s, the occurrence probability of the moraine lake burst is high, and a red early warning signal is sent out.
In the step b, when the gradient beta of the abrupt slope section is more than or equal to 25 degrees, the damage mode of the started coarse-grain armor layer is the integral starting, and the critical water level H is determined by the moraine lake C Calculated by formula 1;
H C ＝h 0 +0.75D+1
When the gradient beta of the abrupt slope section is less than 25 DEG, the damage mode of the coarse-grain armor layer started is single starting, and the critical water level H is determined by the moraine lake C Calculated by formula 2;
H C ＝h 0 ++ (2.45-0.1K) D2;
wherein H is C Determining critical water level for tillite lake; d is the average medium diameter particle diameter of the coarse-grain armor layer of the overflow channel; beta is the gradient of the steep slope section, K is the gradient difference between the gradient of the steep slope section and the gradient of the gentle slope section of the overflow channel, K is less than or equal to 20, and when K is more than 20, K is 20; h is a 0 The existing water level of the tillite lake is the surface height difference between the inlet section of the overflow port and the coarse-grain armor layer.
In the preferred embodiment, the direct cause of the burst of the moraine lake is that the water level of the moraine lake exceeds the critical water level for starting the erosion overflow channel, and the indirect cause is that the temperature rises to melt snow or rainfall; ice collapse occurs in a relatively large volume; the larger ice disintegration body enters the tillite lake to cause more water level rising; the landslide or collapse with larger volume enters the ice lake to cause more water level rise; the ice lake upstream of the tillite lake breaks up, so that a large amount of water enters the tillite lake, and the water level rises; according to the method, the factor of the rising water level of the tillus lake, which directly causes the collapse of the tillus lake, is more directly considered as the early warning index, and the uncertainty of other indirect influencing factors is avoided, so that the early warning accuracy is higher, and the adaptability is stronger.
Example 3
An overflow water level early warning method for ice lake burst comprises the following steps:
a. survey and measure overflow channel of tillite lake, measure average medium diameter particle diameter D of coarse granule armor layer of overflow channel, measure gentle slope section slope alpha and abrupt slope section slope beta of overflow channel, measure the surface difference of height h of existing water level of tillite lake at overflow mouth entrance section and coarse granule armor layer 0 If the existing water level of the tillite lake is lower than the surface of the coarse-grain armor layer, h 0 If the existing water level of the tillite lake is higher than the surface of the coarse-grain armor layer, h 0 Negative;
b. according to the gradient beta of the steep slope section of the overflow channel, determining the damage mode of the started coarse-grain armor layer of the overflow channel, and determining the critical water level H of the burst of the ice, the lake C ；
c. Building water level monitoring points around the overflow port, measuring the existing water level of the tillite lake, and carrying out monitoring and early warning according to the existing water level of the tillite lake as a basic water level;
d. dividing early warning grades, and when the monitoring water level H of the tillite lake is less than 0.75H C The occurrence probability of the moraine lake burst is very small, and a green safety signal is sent out; when the water level H of the tillite lake is more than or equal to H C The duration is less than 30s, the occurrence probability of the moraine lake burst is small, and a yellow early warning signal is sent; when the water level H monitored by the tillite lake is more than or equal to 0.75H C The duration is longer than 30s, and an orange early warning signal is sent out in the occurrence probability of the moraine lake burst; when the water level H of the tillite lake is more than or equal to H C And the duration is longer than 30s, the occurrence probability of the moraine lake burst is high, and a red early warning signal is sent out.
In the step b, when the gradient beta of the abrupt slope section is more than or equal to 25 degrees, the damage mode of the started coarse-grain armor layer is the integral starting, and the critical water level H is determined by the moraine lake C Calculated by formula 1;
H C ＝h 0 +0.75D+1
When the gradient beta of the abrupt slope section is less than 25 DEG, the damage mode of the coarse-grain armor layer started is single starting, and the critical water level H is determined by the moraine lake C Calculated by formula 2;
H C ＝h 0 ++ (2.45-0.1K) D2;
wherein H is C Determining critical water level for tillite lake; d is the average medium diameter particle diameter of the coarse-grain armor layer of the overflow channel; beta is the gradient of the steep slope section, K is the gradient difference between the gradient of the steep slope section and the gradient of the gentle slope section of the overflow channel, K is less than or equal to 20, and when K is more than 20, K is 20; h is a 0 The existing water level of the tillite lake is the surface height difference between the inlet section of the overflow port and the coarse-grain armor layer.
In the step d, the monitoring water level H of the tillite lake refers to comparing the water level after the water level is measured at the moment.
In the embodiment, the coarse-grain armor layer is used for starting the whole grain of the coarse-grain armor layer in consideration of different mechanisms of rising and eroding the overflow channel on the water level of the moraine lake, and the proper water level breaking condition is given under the condition of large gradient of the steep slope section of the overflow channel, so that the applicability is strong.
Considering different mechanisms of rising and starting up the coarse-grain armor layer which erodes the overflow channel on the water level of the moraine lake, the mechanism of starting up the single grain of the coarse-grain armor layer is utilized, the starting up can be formed below 25 degrees of the abrupt slope section and the gentle slope section of the overflow channel at the turning point of the abrupt slope section, the proper water level breaking condition is given, and the applicability is enhanced.
Example 4
An overflow water level early warning method for ice lake burst comprises the following steps:
a. survey and measure overflow channel of tillite lake, measure average medium diameter particle diameter D of coarse granule armor layer of overflow channel, measure gentle slope section slope alpha and abrupt slope section slope beta of overflow channel, measure the surface difference of height h of existing water level of tillite lake at overflow mouth entrance section and coarse granule armor layer 0 If the existing water level of the tillite lake is lower than the surface of the coarse-grain armor layer, h 0 If the existing water level of the tillite lake is higher than the surface of the coarse-grain armor layer, h 0 Negative;
b. according to the gradient beta of the steep slope section of the overflow channel, determining the damage mode of the started coarse-grain armor layer of the overflow channel, and determining the burst of the ice, the lakeCritical water level H C ；
c. Building water level monitoring points around the overflow port, measuring the existing water level of the tillite lake, and carrying out monitoring and early warning according to the existing water level of the tillite lake as a basic water level;
d. dividing early warning grades, and when the monitoring water level H of the tillite lake is less than 0.75H C The occurrence probability of the moraine lake burst is very small, and a green safety signal is sent out; when the water level H of the tillite lake is more than or equal to H C The duration is less than 30s, the occurrence probability of the moraine lake burst is small, and a yellow early warning signal is sent; when the water level H monitored by the tillite lake is more than or equal to 0.75H C The duration is longer than 30s, and an orange early warning signal is sent out in the occurrence probability of the moraine lake burst; when the water level H of the tillite lake is more than or equal to H C And the duration is longer than 30s, the occurrence probability of the moraine lake burst is high, and a red early warning signal is sent out.
In the step b, when the gradient beta of the abrupt slope section is more than or equal to 25 degrees, the damage mode of the started coarse-grain armor layer is the integral starting, and the critical water level H is determined by the moraine lake C Calculated by formula 1;
H C ＝h 0 +0.75D+1
When the gradient beta of the abrupt slope section is less than 25 DEG, the damage mode of the coarse-grain armor layer started is single starting, and the critical water level H is determined by the moraine lake C Calculated by formula 2;
H C ＝h 0 ++ (2.45-0.1K) D2;
wherein H is C Determining critical water level for tillite lake; d is the average medium diameter particle diameter of the coarse-grain armor layer of the overflow channel; beta is the gradient of the steep slope section, K is the gradient difference between the gradient of the steep slope section and the gradient of the gentle slope section of the overflow channel, K is less than or equal to 20, and when K is more than 20, K is 20; h is a 0 The existing water level of the tillite lake is the surface height difference between the inlet section of the overflow port and the coarse-grain armor layer.
In the step d, the monitoring water level H of the tillite lake refers to comparing the water level after the water level is measured at the moment.
The method is suitable for early warning of the burst of the tillite lake caused by the rising of the water level of the tillite lake.
The invention is suitable for the pre-warning of the burst of the water level of the tillus lake caused by the fact that the glacier is subjected to ice collapse, landslide or collapse and enters the tillus lake.
Furthermore, the invention is suitable for the early warning of the burst of the tillite lake caused by rising of the water level of the tillite lake due to rainfall or ice and snow melting.
Furthermore, the invention is suitable for the early warning of the burst of the moraine lake, which is caused by the burst of the upper stream moraine to cause the rise of the water level of the moraine lake.
In this embodiment, as the best mode, the breaking mechanism is that the water level of the erosion position of the coarse particle armor layer of the overflow channel is raised, specifically, the water level of the turning point of the steep slope section or the steep slope section and the gentle slope section is raised, but the water level monitoring is very difficult to set up at the position, the monitored water level fluctuates greatly due to the influence of the boulder, the correct monitored water level is difficult to be given, and the inlet water level of the overflow channel is adopted during monitoring, and the monitoring and early warning are carried out in combination with the current water level of the moraine lake, so that the break of the moraine lake can be well early warned, and the method has strong applicability.
The method is suitable for early warning of the burst of the tillite lake caused by the rising of the water level of the tillite lake; the method is suitable for early warning of the collapse of the tillite lake caused by the water level rising of the tillite lake due to the fact that the glacier is subjected to ice collapse, landslide or collapse into the tillite lake; the method is suitable for early warning of the burst of the tillite lake caused by rising of the water level of the tillite lake due to rainfall or ice and snow melting; the method is suitable for early warning of the burst of the moraine lake caused by the burst of the upstream moraine lake, and has wide applicability.
The invention is adopted to respectively carry out burst judgment on the water level rising events of six burst tillus lakes and two burst tillus lakes:
the burst and burst tillite lakes are predominantly distributed in the Tibet, with only one located in the Combretas province of Douglas, canada (Queen Bees). Some of the rising water level of the tillite lake is calculated according to the volume of the ice disintegration body and the area of the tillite lake, and other water levels are directly derived from literature. Since the slopes of the steep and gentle slope sections upstream and downstream of the overflow channel turning points of these breaking tillite lakes are not detailed, we use a lower water level for evaluation, i.e. the lowest water level is chosen, and K takes the maximum value, for safety reasons: k=20, and the single start-up critical level at this time is lower than the entire start-up critical level of a large gradient, and thus the critical level is adopted as the early warning critical level.
In addition, let h 0 =0.5D, i.e., the water level before an emergency, typically in summer or rainy season, ice collapse, landslide or collapse, or sudden heavy rain or high temperature snow melting, or the water level before the burst of an upstream sudden iced lake, then expression 1 and expression 2 can be combined as:
H C =0.5d+0.45d=0.95D 3
As can be seen from the formula 3 and the early warning level, h=0.95d is a red early warning line; h=0.75×0.95d=0.71D is an orange warning line. According to literature data, armor layer particle diameters between 0.5 and 2m are assumed. The name of the moraine lake, the time to burst and burst, the reason for burst, and the water level H monitored for the moraine lake for these events are given in table 1. FIG. 1 is a graph of the average median diameter D of the coarse-grain armor layer of the overflow channel versus the water level H monitored in the tillus lake for these events, which data demonstrates the accuracy of the present invention in predicting these ice collapse/landslide events, except: 1) When d=0.5m, two points which are not collapsed are in an orange early warning range; 2) At d=2m, the pre-warning of light error is lower than the orange pre-warning.
TABLE 1
| Name of tillite lake | Time of burst and burst | Cause of ulcer | Monitoring Water level H (m) of tillite lake |
| Minor kernel-marc error | 1981-07-11 | Ice collapse/piping | 12.8 |
| Ji Lai error | 1964-09-21 | Ice-disintegrating | 7 |
| Daphla cough with stuffy feeling | 1964-09-26 | Ice-disintegrating | 23.8 |
| Parvos of parvos | 1972-07-23 | Ice-disintegrating | 10.3 |
| Light Xie Cuo | 1988-07-15 | Ice collapse/piping | 1.19 |
| Queen Bees | 1997-08-12 | Ice-disintegrating | 2.96 |
| Light Xie Cuo | 1990-7-8 months | Ice collapse/non-collapse | 0.45 |
| Ji Wengcuo | 2020-06-21 | Landslide/non-break | 0.39 |
In the case of the misbroken cases of lights Xie Cuo and Ji Weng, the exception occurred only when the coarse size of the armor layer was about 0.5m, apparently due to the assumption that the sizes of the armor layers of the two ice lakes were too small, because the coarse size of the armor layer of the field ice lake was mostly above 1 m. In the case of the optical Xie Cuo burst, the burst is caused by the occurrence of the ice burst, and another cause is caused by the burst: piping also occurs at the time, which makes the burst easier to occur, so that the early warning of the light error is calculated to be successful.
In conclusion, the early warning success rate of the burst of the tillus and lake is very high, and early warning can be effectively provided for the burst of the tillus and lake caused by overflow of the tillus and lake.
Claims (7)
1. An overflow water level early warning method for ice lake burst is characterized by comprising the following steps:
a. survey and measure overflow channel of tillite lake, measure average medium diameter particle diameter D of coarse granule armor layer of overflow channel, measure gentle slope section slope alpha and abrupt slope section slope beta of overflow channel, measure the surface difference of height h of existing water level of tillite lake at overflow mouth entrance section and coarse granule armor layer 0 If the existing water level of the tillite lake is lower than the surface of the coarse-grain armor layer, h 0 If the existing water level of the tillite lake is higher than the surface of the coarse-grain armor layer, h 0 Negative;
b. according to the gradient beta of the steep slope section of the overflow channel, determining the damage mode of the started coarse-grain armor layer of the overflow channel, and determining the critical water level H of the burst of the ice, the lake C ；
c. Building water level monitoring points around the overflow port, measuring the existing water level of the tillite lake, and carrying out monitoring and early warning according to the existing water level of the tillite lake as a basic water level;
d. dividing early warning grades, and when the monitoring water level H of the tillite lake is less than 0.75H C The occurrence probability of the moraine lake burst is very small, and a green safety signal is sent out; when the water level H of the tillite lake is more than or equal to H C But the duration is less than 30s, the moraine lake is brokenThe occurrence probability is small, and a yellow early warning signal is sent out; when the water level H monitored by the tillite lake is more than or equal to 0.75H C The duration is longer than 30s, and an orange early warning signal is sent out in the occurrence probability of the moraine lake burst; when the water level H of the tillite lake is more than or equal to H C And the duration is longer than 30s, the occurrence probability of the moraine lake burst is high, and a red early warning signal is sent out.
2. The overflow water level early warning method for ice lake burst according to claim 1, wherein the method comprises the following steps: in the step b, when the gradient beta of the abrupt slope section is more than or equal to 25 degrees, the damage mode of the started coarse-grain armor layer is the integral starting, and the critical water level H is determined by the moraine lake C Calculated by formula 1;
H C ＝h 0 +0.75D+1
When the gradient beta of the abrupt slope section is less than 25 DEG, the damage mode of the coarse-grain armor layer started is single starting, and the critical water level H is determined by the moraine lake C Calculated by formula 2;
H C ＝h 0 ++ (2.45-0.1K) D2;
wherein H is C Determining critical water level for tillite lake; d is the average medium diameter particle diameter of the coarse-grain armor layer of the overflow channel; beta is the gradient of the steep slope section, K is the gradient difference between the gradient of the steep slope section and the gradient of the gentle slope section of the overflow channel, K is less than or equal to 20, and when K is more than 20, K is 20; h is a 0 The existing water level of the tillite lake is the surface height difference between the inlet section of the overflow port and the coarse-grain armor layer.
3. The overflow water level early warning method for ice lake burst according to claim 1, wherein the method comprises the following steps: in the step d, the monitoring water level H of the tillite lake refers to comparing the water level after the water level is measured at the moment.
4. The application of the overflow water level early warning method for ice lake burst according to claim 1, which is characterized in that: the method is suitable for early warning of the burst of the tillite lake caused by the rising of the water level of the tillite lake.
5. The application of the overflow water level early warning method for ice lake burst according to claim 1, which is characterized in that: the method is suitable for early warning of the collapse of the tillite lake caused by the water level rising of the tillite lake due to the fact that the glacier is subjected to ice collapse, landslide or collapse into the tillite lake.
6. The application of the overflow water level early warning method for ice lake burst according to claim 1, which is characterized in that: the method is suitable for early warning of the burst of the moraine lake caused by rising of the water level of the moraine lake due to rainfall or ice and snow melting.
7. The application of the overflow water level early warning method for ice lake burst according to claim 1, which is characterized in that: the method is suitable for early warning of the burst of the moraine lake caused by the burst of the upstream moraine lake.
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