Asymmetric debris flow drainage trough and design method and application thereof

An asymmetric debris-flow discharge channel comprising:

• a main drainage channel for discharging a debris flow according to a predetermined standard, wherein the main drainage channel comprises side walls;
• an auxiliary channel provided outside of the main drainage channel, wherein the auxiliary channel comprises side walls that are integrated with the side walls of the main drainage channel or provided outside of the side walls of the main drainage channel, wherein the auxiliary channel has a top width defined by the side walls of the auxiliary channel;
• and
• a break section integrated into a side wall of the auxiliary channel, wherein the break section has a top width,
• wherein the top width of the break section is equal to the top width of the auxiliary channel;
• and
• wherein the side walls of the auxiliary channel side wall and the break section are made of different building materials selected from a group consisting of masonry, gabions, and concrete.

A method of building an asymmetric debris-flow discharge channel, the method comprising:

• step 1:
• determining a debris-flow density γdebris flow in the unit of kN/m3 through on-site survey and measuring,
• determining a debris-flow peak discharge Qtotal in the unit of m3/s by using a small-watershed hydrologic calculation method,
• determining a peak flood discharge by using the small-watershed hydrologic calculation method, and
• determining a critical debris-flow peak discharge Qmain river in the unit of m3/s based on the determined peak flood discharge, wherein the critical debris-flow peak discharge is the volume of a debris flow that causes blockage of a river when the debris flow is discharged into the river from the drainage channel;
• step 2:
• determining a building material of a break section of the asymmetric debris-flow discharge channel through on-site survey and measuring,
• determining a density of the break section γbreak section in the unit of kN/m3 according to the determined building material, and
• determining a top width of the break section b0 in the unit of m and a height h2 of an auxiliary channel of the asymmetric debris-flow discharge channel in the unit of m through on-site survey and measuring;
• step 3:
• determining a debris-flow depth hdebris-flow depth in the unit of m in the auxiliary channel using a method of cross-section superposition for calculating the discharge in a compound channel;
• step 4:
• determining a length L0 of the break section by using the following equation:
• L
• 0
• =
• Q
• total
• -
• Q
• main
• 
• 
• river
• ϕ
• 
• 2
• 
• g
• 
• h
• debris
• 
• -
• 
• flow
• 
• 
• depth
• 3
• 
• /
• 
• 2
• wherein:
• L0=the length of the break section in the unit of m,
• Qtrial=the debris-flow peak discharge determined in step 1,
• Qmain river=the critical debris-flow peak discharge determined in step 1,
• φ=a comprehensive coefficient ranging from 0.2 to 0.5,
• g=acceleration due to gravity, and
• hdebris-flow =the debris-flow depth determined in step 3;
• and
• step 5:
• calculating a height h0 of the break section by using the following equation, under the condition that h0<h2:
• h
• debris
• 
• -
• 
• flow
• 
• 
• depth
• <
• h
• 0
• <
• γ
• debris
• 
• 
• flow
• ×
• h
• debris
• 
• -
• 
• flow
• 
• 
• depth
• 3
• 3
• 
• (
• γ
• break
• 
• 
• section
• ×
• b
• 0
• 2
• )
• wherein:
• h0=the height of the break section in the unit of m,
• hdebris-flow depth=the debris-flow depth determined in step 3,
• γbreak section=the density of the break section determined in step 2,
• γdebris flow=the debris-flow density determined in step 1, and
• b0=the top width of the break section determined in step 2.