Dangerous situation of Yellow River dike for reference of Yellow River Committee.

1. What are the nine dangers of dikes?

Answer: overflow, leakage, piping, leakage, landslide, collapse, collapse, cracks, wind and waves.

2. What is overflow?

A: The flood overflowed from the top of the dike and suddenly washed the dike body from top to bottom, causing the dike to burst.

3. What are the causes of dike overflow?

Answer: (1) An over-standard flood occurred in the upper reaches, and the flood level exceeded the top of the dike;

(2) There are water blocking obstacles in the river, and the water level is higher than the top of the dike;

(3) Due to river siltation, the water level rises above the crest;

(4) Wind waves or mainstream bends cause the water level to rise above the top of the dike;

(5) Embankment construction is not dense, and the foundation sinks, resulting in insufficient embankment height.

4. What is the principle of emergency protection in case of overflow danger?

A: Strive to complete the dam construction before the flood comes.

5. What are the methods to protect the overflow danger?

Answer: Pure land, earth bags, willow piles and willow pillows.

6. What should I pay attention to when repairing my child?

Answer: (1) Ensure the quality of emergency repair; (2) The emergency repair sub-tunnel should be constructed synchronously along the whole line; (3) The repaired sub-year should be closely inspected and the defense should be strengthened. Find problems and protect the next year in time.

7. What is water seepage?

A: Under the action of high water level and long-term seepage pressure, the soil is wet or soft, and there is water seepage near the toe of backwater dike.

8. What is the cause of seepage in the dike?

Answer: (1) The water level exceeds the dike design standard; (2) insufficient lifting section; (3) The embankment is sandy soil with strong water permeability; (4) Improper compaction of embankment; (5) There are hidden dangers in the dam and foundation.

9. What is the principle of water seepage and grab protection for dikes?

Answer: Seepage is intercepted when facing water, and seepage is conducted when facing back water.

10. What is the emergency protection method for dike leakage?

Answer: Seepage-guiding trench method, reverse filter layer method, water seepage method and water interception method.

1 1. What should I pay attention to in case of water seepage?

Answer: (1) Try to avoid trampling in the seepage area; (2) When there is a pit near the toe of the seepage-proof embankment, stones or soil bags should be thrown at the toe of the embankment to consolidate the foundation while protecting the seepage-proof danger; (3) Sand and gravel permeability should be strictly layered to minimize trampling; (4) Geotextiles should be exposed as far as possible.

What is a pipeline?

Answer: The soil near the toe of the backwater slope of the dike (dam) is in danger of seepage deformation and water and sand collapse due to the seepage pressure of seepage water.

13. What is the cause of pipeline danger?

Answer: The embankment foundation is strongly permeable, or the surface of the permeable foundation is covered with cohesive soil, but it is destroyed. When the water level rises, the seepage gradient becomes steeper and the seepage velocity and pressure increase. When the permeability gradient is greater than the allowable permeability gradient of embankment foundation soil, seepage failure will occur and piping will form. Or under the viscous cover with back water, it bears great seepage pressure, breaks through the soil layer at the weak place, and the seepage takes away the fine sand particles in the lower layer, resulting in piping.

14. What is the principle of pipeline emergency protection?

Answer: Filter conductive seepage to prevent seepage damage and prevent water gushing from carrying sand. Koshimizu pipeline, can strengthen the observation, temporarily no matter. Muddy water piping, big or small, must be washed and protected quickly.

15. Is there any way to protect the piping?

Answer: filtration method, decompression method, filtration method and penetration method.

16. How to protect underwater pipelines?

Answer: (1) If the manpower, time and borrowing conditions can complete the task quickly, the pond filling method can be used. Cut off the water potential with stones and bricks first, and then fill the pit with sand or coarse sand.

(2) When the pit and pond are too large and the filling will delay the time, the underwater filter layer method can be used. First, plug the serious piping, cut off the water potential, and then directly inject sand filter material from the water according to the requirements of stratification to form a reverse filter pile to control the development of dangerous situations.

(3) Use pipes to introduce water into the pond, so as to raise the water level in the pond and prevent sand piping.

17. What should I do? Cowhide bag? ?

A: appear? Cowhide bag? Spread a layer of grass, wheat straw or straw with a thickness of 10~20cm, and then spread a layer of reed, straw or willow branches with a thickness of 20~30cm. When the thickness is more than 30cm, it can be laid in two layers. After laying, puncture the surface of the drum bag with an awl to discharge the moisture and air inside, and then press a stone or soil bag for treatment.

18. What should I pay attention to when trying to protect piping?

Answer: (1) When piping in backwater treatment, it is forbidden to forcibly fill hard plugs with impermeable materials; (2) Avoid using cohesive soil to build infiltration platform; (3) The dam around the unfiltered well should have sufficient height and strength.

19. What is a vulnerability?

Answer: In flood season or high water level, there are water holes passing through the dike body or foundation near the back slope and toe of the dike.

20. What is the reason for the loophole?

Answer: (1) The quality of embankment and foundation is poor; (2) There are hidden dangers in the dike body, and there are old gates in the dike foundation; (3) Where the leakage is seriously concentrated, the soil in the dike is taken away, and the effluent changes from clear to turbid, and the holes change from small to large, forming loopholes.

2 1. What is the principle of protecting loopholes and dangers?

A:? Front gear and rear guide? It is necessary to grasp early and small at one go.

22. What are the detection methods of leakage air inlet?

Answer: (1) chaff spreading method; (2) Bamboo hanging ball method; (3) bamboo pole detection method; (4) several people grope side by side; (5) diving exploration; (6) Check the holes in curtains, woven fabrics and mats; (7) Floating depth leak detector.

23. What are the ways to protect vulnerability and danger?

Answer: (1) He Lin interception: ① plugging method, ② sealing method, ③ breakwater method; (2) Back water protection: ① filtration method, ② decompression method, ③ filtration method, ④ platform penetration method.

24. What should we pay attention to when robbing loopholes and dangers?

Answer: (1) Strengthen leadership, unify command, take appropriate measures and act quickly; (2) Pay attention to the safety and personal safety of the project; (3) Use enough cohesive soil to block the breath, strengthen it, and guard it by special personnel; (4) Don't throw blocky substances at the water inlet, and don't pile up at the water outlet or plug it with impervious materials; (5) When the capping method is adopted, after the hole is covered, it should be immediately closed around, and the air should be quickly sealed by pressing the soil.

25. What is a landslide?

Answer: the danger caused by the instability and sliding of embankment slope.

26. What is the cause of landslide danger?

Answer: (1) The high water level caused the landslide on the back slope; (2) The sudden drop of water level leads to landslide near the water slope; (3) The embankment foundation is defective.

27. What is the principle of landslide emergency protection?

Answer: The principle of grabbing and protecting the landslide on the back water slope is to return the slope with seepage and restore the integrity of the dike slope. The principles of grabbing and protecting the landslide near the water slope are: protecting the foot, cutting the slope and reducing the load.

28. What are the emergency protection methods for landslides?

Answer: Soil and water conservation adopts filtration, post-filtration, filtration and slope return, pre-filtration and seepage interception, toe protection and anti-sliding.

29. What should I pay attention to when grabbing the landslide danger?

Answer: (1) Once found, deal with it immediately. (2) When the seepage ditch is carried out on the landslide, it should be dug as far as possible to the sliding surface, otherwise it will not work; (3) On the landslide with serious water seepage, it is necessary to avoid trampling as much as possible to avoid the danger from expanding; (4) In backwater landslide, when the bearing capacity of soil is insufficient, it is not advisable to load soil too quickly or excessively.

30. What is a nest drop?

A: It's also called a pit. Before and after the general rainstorm, the local dike suddenly collapsed, which is a dangerous situation.

3 1. What is the cause of falling danger?

Answer: (1) There are hidden dangers in the dike; (2) The dike quality is poor; (3) accompanied by water seepage, piping or stratum leakage.

32. What's the principle of emergency protection in case of falling nest?

A: Pay close attention to repair and protection to prevent the danger from expanding.

33. Is there any way to save the nest?

Answer: (1) Dumping tamping method; (2) plugging method; (3) Filling filter material method.

34. What should I pay attention to when catching the nest?

Answer: (1) Find out the reason, choose different methods according to different situations, and rush to protect quickly; (2) When digging, the slope should be reserved according to the soil quality or supported by wood to avoid collapse and expansion.

35. What is a crash?

Answer: Because of the change of river regime, the bank slope is washed by the big river, or the high water level suddenly drops, and the bank slope is unstable, resulting in bank collapse or landslide.

36. What is the cause of the collapse danger?

Answer: When water washes away the dam, the internal friction and cohesion of the soil can't resist its own weight and other external forces, and the soil loses its balance and collapses.

37. What is the principle of grabbing the collapse danger?

Answer: It is mainly based on solid foundation, foot protection and erosion prevention to prevent further collapse.

38. What are the methods to protect the collapse danger?

Answer: ① foot protection and erosion prevention method; (2) sinking willow to protect feet; ③ Pile-firewood slope protection (scattered box) method; ④ Liu's soft embrace method; ⑤ Liu's box holding method.

39. What should I pay attention to when robbing a landslide?

Answer: (1) You can't just pay attention to dangerous work and ignore flat work; (2) Special attention should be paid to the danger of slipping and embankment collapse; (3) Pay attention to falling into the water.

40. How to classify the crack risk?

Answer: According to parts: surface cracks and internal cracks; According to strike: transverse crack, longitudinal crack and turtle crack; According to the causes: subsidence cracks, shrinkage cracks, freezing cracks, vibration cracks.

4 1. What is the reason for the danger of cracks?

Answer: (1) The bearing capacity of embankment soil is quite different, causing uneven settlement; (2) large water content during construction, resulting in shrinkage or cracking; (3) Silty soil, frozen soil and hard clods are placed on the embankment when the embankment is repaired, and the compaction is not solid; (4) Under the action of high water seepage, the backwater dike slope slides; (5) The toe of the waterfront dike was washed away, and the water level plummeted and the dike slope slipped; (6) There are hidden dangers in the dike body; (7) it is not well combined with the building.

42. What should I do first to grab the crack insurance?

A: Determine the reason first.

43. What is the method of crack emergency protection?

Answer: ① joint filling should be strict; (2) excavation and backfilling; (3) Mold partition wall.

44. What should we pay attention to when grasping the crack risk?

Answer: (1) When cracks are accompanied by collapse and landslide, they should be protected first, and then they should be protected according to cracks after they are out of danger and tend to be stable; (2) Open or blocked cracks should be observed; (3) Whether it is necessary to pre-filter and reverse-filter the transverse wall partition; Whether there is only pre-filtration or reverse filtration and permeability without partition wall depends on the specific situation.

45. What is the most dangerous crack in the dike?

A: Transverse cracks.

46. What are the dangers of wind and waves?

A: After the flood season, the water depth in front of the dike increases, and the dike slope is in danger of being destroyed under the continuous impact of wind and waves.

47. What is the cause of the storm?

A: On the one hand, there are problems in the dike itself, such as insufficient height, thin section, poor soil quality, poor compaction, poor foundation and poor anti-scouring ability. On the other hand, it is related to the wind and waves, such as the blowing distance in front of the dike, the water depth, the high wind speed, and the consistency of wind direction and blowing distance.

48. What is the principle of emergency protection under storm conditions?

Answer: According to the reduction of wind and wave impulse, the erosion resistance of dike slope is strengthened.

49. What is the method of emergency protection under storm conditions?

Answer: ① Hang willows to prevent waves, ② Hang pillows to prevent waves, ③ Use earth bags to prevent waves, ④ Use willow foil to prevent waves, ⑤ Use wooden rafts to prevent waves, ⑦ Use lake grass to prevent waves, ⑦ Use piled willows to prevent waves, and ⑧ Use geomembrane to prevent waves.

50. What should I pay attention to when trying to protect the wind and waves?

Answer: (1) Try not to pile on the embankment slope. When piling is required, the pile spacing should be sparse; (2) What is the need for storm protection? Prevention first, prevention is more important than robbery? ; (3) Take temporary wave prevention measures in flood season, which requires a lot of materials, has poor effect and is prone to problems.