i'm not very technical, but i do think that there is a section of your paragraph that could be improved in terms of grammatical structure.
"It is assumed that water pressure acts to the flood gate is resisted by reinforced concrete wall at its ends. These walls are expected to subject a large overturning moment. Therefore, piles are designed to distribute at 1.5m spacing at these position which has a closer distance than an uniform 3.0m spacing"
you could improve these sentences by making it as follows:
"It is assumed that the water pressure, acting to the flood gate, is resisted by reinforced concrete wall at its ends. These walls are likely to be subjected toa large overturning moment (momentum?). As a solution to the issue, (you can elaborate more on the issue here) piles are designed to be distributed at 1.5m spacing at these positions which ,in this case, is more appropriate than the typical uniform 3.0m spacing.