Average Width of the Sewer Trench

[kiwi]

Just like the title says I'm trying to find the average width of the sewer trench. I'm wondering if anyone would be so kind as to help me as how I would go about this. Thank you very much.

 

[Deleted member 4993]

Just like the title says I'm trying to find the average width of the sewer trench. I'm wondering if anyone would be so kind as to help me as how I would go about this. Thank you very much.

I am confused about - what you are calling average width of the trnch.

The cross-section of the trench is a symmetric trapezoid.

Average width of a trapezoid (the parallel sides) would be 1/2 * (max. width + min.width)

But I have feeling that - you are NOT asking about that!

Please elaborate - we here do not know anything about requirements of trenches!!

 

[stapel]

I'm trying to find the average width of the sewer trench. I'm wondering if anyone would be so kind as to help me as how I would go about this.

"How one would go about this" will depend upon the exact text of the exercise and its instructions, along with whatever topics you have recently studied in class (so we know what sorts of tools you have available to you).

Note: In "real life", one suspects that the vertically-walled trenches (minimizing damage to the overlying pavement, yard, whatever, would be the norm, and then "average" would probably depend upon whether one was referring to a trunk line (like the one down the street in front of your house) or the feeder line (from your house to the street), as well as the relevant local, state, and Federal codes, as applicable.

When you reply, please include a clear listing of your thoughts and efforts so far. Thank you!

 

[Ishuda]

Just like the title says I'm trying to find the average width of the sewer trench. I'm wondering if anyone would be so kind as to help me as how I would go about this. Thank you very much.

Taking things at (what I consider) face value, you have a trench 500mm in width at the bottom rising to an unknown width at the top of the trench [at the rough grade] of unknown height. However you do know the slope of the sides of the trench which gives
x = 2 [ 250 + (2/3) y ] = 2 * half width
where x is the width of the trench and y is the vertical distance from the bottom of the trench. So, if you knew the height h of the trench then
x_min = 500
x_max =500 + (4/3) h
and the average width, ala Subhotosh Khan, is
x_avg = 0.5 (x_max + x_min) = 500 + (2/3) h

 

[kiwi]

and the average width, ala Subhotosh Khan, is
x_avg = 0.5 (x_max + x_min) = 500 + (2/3) h

I'm very bad at math which is why I joined this forum. Can you please explain why 500 + (2/3)h; would give us the height? Basically what you have written is MINx + (slopex/slopey)h
is that a formula?