Method of designing box-type energy-dissipating section of box-type energy-dissipating mudflow diversion flume, and application

A method for designing an energy dissipation structure section of a drainage channel,

• wherein the drainage channel comprises a smooth channel, sidewalk, and the energy dissipation structure section;
• wherein the energy dissipation structure section comprises a transverse ground sill and a precast reinforced concrete energy dissipation box;
• wherein the energy dissipation structure section has a top surface that is open and the remaining five sides of the energy dissipation structure section are closed with stones;
• and
• wherein the height of filled stones in the box is 0.5 to 0.8 times the height of the energy dissipation structure section,
• the method comprising:
• step 1:
• determine a channel slope J of the drainage channel through a field survey and topographic map measurements;
• determining a construction material through a field survey and obtain the roughness coefficient n0 of the smooth channel;
• and determining a predetermined velocity through a field investigation;
• step 2:
• setting a length and a width of the energy dissipation structure section and a mean diameter of the filled stones according to a designed debris flow discharge and the channel slope J determined in step 1;
• step 3:
• determining the roughness coefficient n of the energy dissipation structure section using the following formula:
• n
• =
• (
• 0.0136
• ·
• bL
• π
• ⁢
• ⁢
• D
• 2
• ·
• J
• 1
• ⁢
• /
• ⁢
• 2
• +
• 1.1921
• )
• ·
• n
• 0
• where
• n—roughness coefficient of the energy dissipation structure section;
• n0—roughness coefficient of the smooth channel determined in step 1;
• b—width of the energy dissipation structure section determined in step 2;
• L—length of the energy dissipation structure section determined in step 2;
• D—mean diameter of the filled stones determined in step 2;
• J—slope of drainage channel determined in step 1;
• and
• π—Pi;
• step 4:
• applying the parameters obtained in steps 1 through 3 into a Manning formula, wherein the debris flow velocity is obtained as follows:
• V
• =
• 1
• n
• ⁢
• R
• 2
• ⁢
• /
• ⁢
• 3
• ·
• J
• 1
• ⁢
• /
• ⁢
• 2
• where V is the debris flow velocity, n is for the roughness coefficient of the energy dissipation structure section determined in step 3, R is the hydraulic radius, and J is the channel slope determined in step 1;
• step 5:
• comparing the debris flow velocity calculated in step 4 with the predetermined velocity determined in step 1,
• wherein if the debris flow velocity obtained in step 4 is not equal to the predetermined velocity determined in step 1, reassigning the values of the parameters and repeat steps 2 to 5 until the debris flow velocity obtained in step 4 is equal to the predetermined velocity determined in step 1;
• and
• wherein if the debris flow velocity obtained in step 4 is equal to the predetermined velocity determined in step 1, setting the length and the width of the energy dissipation structure section and the mean diameter of the filled stones determined in step 2 as design parameters of the energy dissipation structure section.