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What is the influence of the rise and fall of groundwater level on the stress in soil? What problems should be fully considered in engineering practice?
When the groundwater level rises, the buoyancy will be increased, which will reduce the friction of the foundation and may cause sliding. When the groundwater level drops, it will change the foundation and may cause settlement. Attention should be paid to the impact on other buildings when dewatering
What is the effect of groundwater level fluctuation on stress distribution in soil
According to the principle of effective stress, u = u ′ + U, we know that: (1) when the groundwater level drops, u decreases and the effective self weight stress in soil increases, which increases the compression of foundation soil and causes the ground surface to sink; (2) when the groundwater level rises, u decreases and the effective self weight stress in soil increases
When the groundwater level rises, does the gravity of soil increase or decrease? What is the specific explanation?
Smaller! This is a common sense problem!
If the base pressure P remains unchanged and the depth of foundation D is increased, the additional stress in soil will decrease and the settlement of foundation will decrease
If the base pressure P remains unchanged, the additional stress in the soil will increase and the settlement of the foundation will decrease with the increase of the buried depth of the foundation. The reasons are as follows: when the buried depth of the foundation increases, the deformation modulus of the foundation soil increases with the increase of the depth, and the stress Z along the load symmetry axis increases
(1) Xiaoming's family has 180 white rabbits, three fifths of which are white rabbits and four fifths of which are grey rabbits?
(2) a tree planting activity was held in a school. 135 trees were planted in grade 4. The trees planted in grade 3 were one third of those planted in grade 4 and five eighteenth of those planted in Grade 5
(3) if the rope a, B and C is folded once, it is exactly three fifths of the rope B. if the rope C is folded three times, it is exactly two fifths of the rope B. It is known that the rope a is 90 meters long. Q: how long are the two ropes B and C?
(1) 180 * 3 / 5 divided by 4 / 5 = 135
(2) 135 * 1 / 3 divided by 5 / 18 = 162 trees
(3) B rope length 90 / 2 divided by 3 / 5 = 75 meters
C rope length 75 * 2 / 5 divided by 1 / 8 = 240m
Some practical problems about grade six of primary school
1. For a project, if team a works alone for 3 days to complete 1 / 5 of the project, and team B works alone for 2 days to complete 1 / 15 of the project, now the two teams cooperate, how many days can they complete the task? (my solution is below, I'll explain)
Solution:
(1) 1 / 5 = 3 / 15
(2) 3 / 15 △ 3 = 1 / 15 (calculate the work efficiency of team a in one day)
(3) 1 / 15 △ 2 = 1 / 30 (calculate the work efficiency of team B in one day)
(3) 1 / 15 + 1 / 30 = 10 days
2. Huayu fruit store brought in a batch of apples and pears, each accounting for 1 / 2 of the total. After 180 boxes were sold, the number of boxes of pears was 1.2 times that of apples. How many boxes of apples and pears did the fruit store send in? Let me tell you what I think.)
Idea:
First draw the line diagram, total number:——
Pear and apple
Since 180 boxes of apples are sold, and apples are pears, there should also be 180 boxes of pears. I think the first step is 180 × 2. Now there is only one 1.2 times, so it can be multiplied by 1.2, but the answer is 2160 boxes, solving the formula and explanation
3. Car a and car B leave from both places at the same time. After 9 hours of meeting, car a runs exactly 2 / 5 of the whole journey. After meeting, car B has to travel for several hours to complete the whole journey? (I don't know.)
Idea:
The corresponding score of 9 hours is 2 / 5, that is, 2 / 5 of the whole journey of a car in 9 hours. I think the first step is 1-2 / 5 = 3 / 5. The answer above is equal to 6 hours. Solve the formula and explain
The first question is right, and the last one is wrong. 1 / 15 + 1 / 30 = 1 / 10, so it's 10 days
Second, after 180 boxes of apples are sold, the number of boxes of pears is 1.2 times that of apples, which is 6:5
If the proportion of pear is half, the proportion of apple is 1 / 2 / 6 * 5 = 5 / 12
1 / 2-5 / 12 = 1 / 12
There are (21180) / 12
The first step is that the distance a takes is exactly the distance b is going to take. Therefore, B has to walk 2 / 5. Before, B took 9 hours to walk 1-2 / 5 = 3 / 5. Then, without 1 / 5 of the distance, B has to walk 3 hours, so (2 / 5) / 1 / 5 * 3 = 6
1. There are four children whose ages differ by one year in turn. The product of their ages is 7920. How old are these four children?
2. Fill in the brackets of 2 () 4 () so that the four digits can be divided by 3 and 5 at the same time. Please write down how many different ways to fill in
1. There are four children whose ages differ by one year from old to young. The product of their ages is 7920. What are the ages of the four? The decomposition factor of 7920 is 2 × 2 × 2 × 2 × 3 × 3 × 5 × 11 = 8 × 9 × 10 × 11, so they are 8 years old, 9 years old, 10 years old and 11 years old. 2
The simpler, the better. Don't be too simple
1 + 1 are all crawling away,
333X333+889X999=999000
99x58=5742
32x25x125=10000
(1) The price ratio of a and B phones is 7:3. If their prices rise by 70 yuan respectively, the price ratio is 7:4. What are the original prices of these two products?
(2) For a rope, cut 5 / 9 of its total length in the first time, and the ratio of the length cut in the second time is 9:20. As a result, there are still 7 meters left. How many meters is the original length of the rope?
(3) When a and B workers go to work, a takes 1 / 5 more distance than B, while B takes 1 / 11 less time than A. what is the speed ratio between a and B?
There's no need to answer the first question
1. Let a be x and B be y
X:Y=7:3 (X+70):(Y+70)=7:4
We get x = 210, y = 90
Application of percentages in Grade 6
A goes to buy two kinds of goods a and B, a is 15% lower than the original price, B is 12% lower than before, buying a and B share 69940 yuan, the average decline of the two kinds of goods is 13.2%
Don't use unknowns
The price ratio of article a and article B is: (13.2% - 12%): (15% - 13.2%) = 2:3
The sum of the original price of article a and article B is: 69940 / (1-13.2%) = 80576.03687 yuan
80576.03687 was divided into 5 parts, 2 for article a and 3 for article B
The original price of article a = 80576.03687 * 2 / 5 = 32230 and 90 / 217 (yuan) is about 32230.4 yuan
The original price of article B = 80576.03687 * 3 / 5 = 48345 and 135 / 217 (yuan) is about 48345.6 yuan
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