How to calculate the uplift pressure on the bottom of stilling b

1. When there is a flood in the upstream, it is necessary to open the sluice to discharge the flood. In order to ensure the safety of flood discharge, when the water level difference between the upstream and downstream is small (such as 0.0.3m), it is still necessary to safely discharge a certain amount of flow, so the total net width of the corresponding sluice hole is needed, During the period of impoundment, the water level difference between the upstream and downstream is often very large. However, when the sluice is opened (from the form of discharge, it is the transition from orifice flow to weir flow), the downstream water level will rise slowly, that is, the water level difference between the upstream and downstream has a process of narrowing. In this process, the energy dissipation situation is constantly changing. In the initial discharge, the downstream water level is generally low, At this time, the problem of energy dissipation is relatively prominent; With the rise of the downstream water level, the submergence degree of the hydraulic jump will increase, and the energy dissipation conditions will be improved, Then, the flow corresponding to the most unfavorable situation is selected as the design flow for determining the depth of stilling basin. The design flow for determining the length of stilling basin is not necessarily the same as that for determining the depth, and it needs to be determined by corresponding combination. In principle, the downstream water depth should be determined according to the relationship curve between water level and flow (which can be calculated according to the measured data or the open discharge uniform flow), However, in practical engineering design, the situation is often not simple, especially for small sluices. The upstream water level is relatively easy to determine, because there will be a normal water level in the design, in addition, there may be a maximum water level, limited water level, etc., so the key depends on the selection of downstream water level, but there is no completely universal method, According to the current situation of the river and the actual application requirements, several characteristic water levels can be selected (generally unsafe, sometimes it is assumed that there is no water in the downstream), and then combined with the characteristic water level in the upstream to calculate the parameters of the energy dissipator

2. The height of the wing wall on the side of the stilling basin can be set as the maximum water depth after the downstream jump when discharging, and then the superelevation can be added.
the filling on the top of the wing wall is treated with masonry revetment instead of setting the top elevation of the wing wall directly to the elevation of the check flood level
the following calculation method is for reference only< (1) determination of stilling basin depth: S = SHC - h t - d z
through calculation, the stilling basin depth is XXM, and the design is XXM

(2) calculation of stilling basin length:
LK = BL J
LJ = XX (fr1-1) (FR1 < XX)
where LK is stilling basin length (m)
b - hydraulic jump length correction coefficient, x ~ x can be used
LJ - hydraulic jump length (m)
through calculation, the length of stilling basin is XXM, and the design is XXM

(3) the calculation of the height of the side wall of the stilling basin: the downstream maximum conjugate water depth HC = XX & quot; According to the engineering design standard, the super height of the side wall of the stilling basin is taken as XXM, so the height of the side wall of the stilling basin calculated from the bottom plate of the stilling basin is (XX + XX) M

X represents the value you want to calculate, or the existing data value!

3. First of all, it is understood that uplift pressure is composed of buoyancy and osmotic pressure. Buoyancy refers to the buoyancy caused by the upstream and downstream water level of the Sluice at the same water level. It can be understood that the sluice is placed in the water of a certain depth, and of course it will be subject to upward buoyancy, which is a rectangular part in the force diagram; The seepage pressure is caused by the water level difference between upstream and downstream, so the stress diagram is a triangular part
sometimes to calculate the uplift pressure is to multiply the uplift pressure coefficient. I've read the book you said before, but I can't remember how to calculate it in my colleagues, but there must be only one method ··
I've just turned it over. In that example, the uplift pressure is given as a condition, and the uplift pressure can't be calculated only by the condition given by him, Because the calculation of seepage pressure involves a series of seepage calculation of upstream blanket and sluice bottom plate, the stability calculation of sluice can only be carried out after the seepage calculation results are obtained.

4. Uplift pressure
calculate uplift pressure including osmotic pressure and buoyancy under normal water retaining level and other water retaining levels respectively. The uplift pressure distribution of dam foundation is calculated according to the linear proportion method, and the resultant force of uplift pressure acting on the bottom plate is obtained
1. Uplift pressure distribution
uplift pressure PU= Υ OhU= Υ O (Zi -)
buoyancy pu1= Υ OhU1= Υ O (Zi - △ h)
osmotic pressure PU2= Υ OhU2= Υ O (△ H -)
where:
△ H - upstream head
Zi - water level difference from calculation point to upstream
Li - seepage length of calculation point

Hu. Hu1 hu2 - uplift pressure of calculation point, buoyancy force and seepage pressure head, uplift pressure resultant force respectively
according to the floor bottom as the uplift pressure level of each point (I), make its distribution map, and then calculate the uplift pressure resultant force according to the distribution map. In order to facilitate the calculation of resultant force acting point, it can be divided into blocks.

5. For structures with seepage field such as earth rock dams, the guiding ideology should be upper plugging and lower drainage. The seepage path is cut off from the upstream and the seepage water is discharged from the downstream to rece the seepage force and uplift pressure. So what you said to do drainage should be done in the downstream side of the drainage, and in the upstream side of the joint to do water stop, so that you can achieve up plugging and down drainage.

6. Remove the water under the bottom plate and rece the uplift pressure

7. Seepage theory is widely used in water conservancy, civil engineering, water supply and drainage, environmental protection, geology, petroleum, chemical instry and many other fields. In water conservancy projects, the most commonly used seepage problems are: the seepage and stability of hydraulic structures on Soil and permeable foundation, the design and calculation of water collecting structures such as wells and water collecting corridors, the lateral seepage of reservoirs and river banks, etc.

8. Pressure in physics refers to the force acting on the contact surface of two objects, or the vertical force of gas on the surface of solid and liquid, or the vertical force of liquid on the surface of solid. Traditionally, in mechanics and most engineering disciplines, the word "pressure" is synonymous with pressure in physics.