ﻤﺠﻠﺔ ﺠﺎﻤﻌﺔ ﺍﻟﻤﻠﻙ ﻋﺒﺩ ﺍﻟﻌﺯﻴﺯ :ﺍﻟﻌﻠﻭﻡ ﺍﻟﻬﻨﺩﺴﻴﺔ ،ﻡ ، 14ﻉ ، 2ﺹ ﺹ 1423) 80 -29ﻫـ 2002 /ﻡ(
ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺍﻟﻤﻤﻠﻜﺔ ﺍﻟﻌﺭﺒﻴﺔ ﺍﻟﺴﻌﻭﺩﻴﺔ :ﺨﻭﺍﺼﻬﺎ ﻭﻁﺭﻕ ﻤﻌﺎﻟﺠﺘﻬﺎ ﺩ .ﻋﺒﺩﺍﷲ ﺒﻥ ﺇﺒﺭﺍﻫﻴﻡ ﺍﻟﻤﻬﻴﺩﺏ
ﻗﺴﻡ ﺍﻟﻬﻨﺩﺴﺔ ﺍﻟﻤﺩﻨﻴﺔ ـ ﻜﻠﻴﺔ ﺍﻟﻬﻨﺩﺴﺔ ـ ﺠﺎﻤﻌﺔ ﺍﻟﻤﻠﻙ ﺴﻌﻭﺩ ﺍﻟﻤﺴﺘﺨﻠﺹ .ﺘﻨﺘﺸﺭ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺍﻟﻤﻤﻠﻜﺔ ﺍﻟﻌﺭﺒﻴﺔ ﺍﻟﺴﻌﻭﺩﻴﺔ ﺤﻭل ﺍﻟﺸﻭﺍﻁﺊ ﺍﻟﻤﻁﻠﺔ ﻋﻠﻰ ﺍﻟﺨﻠﻴﺞ ﺍﻟﻌﺭﺒﻲ ﻭﺍﻟﺒﺤﺭ ﺍﻷﺤﻤﺭ ،ﻜﻤﺎ ﺘﻭﺠﺩ ﻓﻲ ﻤﻨﺎﻁﻕ ﺼﻐﻴﺭﺓ ﺩﺍﺨل ﺍﻟﻤﻤﻠﻜﺔ .ﺤﻴﺙ ﺘﻭﺠﺩ ﻫﺫﻩ ﺍﻟﺘﺭﺒﺔ ﻓﻲ ﻤﻨﺎﻁﻕ ﻋﺩﻴﺩﺓ ﻤﻥ ﺍﻟﻤﻨﻁﻘﺔ ﺍﻟﺸﺭﻗﻴﺔ ﻋﻠﻰ ﺴﺎﺤل ﺍﻟﺨﻠﻴﺞ ﺍﻟﻌﺭﺒﻲ ،ﻭﻓﻲ ﺠﺩﺓ ﻭﺠﻴﺯﺍﻥ ﻭﺃﺒﺤﺭ ﻭﺍﻟﻠﻴﺙ ﻋﻠﻰ ﺴﺎﺤل ﺍﻟﺒﺤﺭ ﺍﻷﺤﻤﺭ .ﻜﻤﺎ ﺘﻭﺠﺩ ﻓﻲ ﻭﺍﺩﻱ ﺍﻟﺴﺭﺤﺎﻥ ﻓﻲ ﺍﻟﻤﻨﻁﻘﺔ ﺍﻟﺸﻤﺎﻟﻴﺔ ﻤﻥ ﺍﻟﻤﻤﻠﻜﺔ ﻭﻓﻲ ﺃﺠﺯﺍﺀ ﻗﻠﻴﻠﺔ ﻤﻥ ﻤﻨﻁﻘﺔ ﺍﻟﻘﺼﻴﻡ ﻭﺍﻟﺭﺒﻊ ﺍﻟﺨﺎﻟﻲ .ﻭﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﺘﺘﻤﻴﺯ ﺒﻤﻠﻭﺤﺔ ﻤﻴﺎﻫﻬﺎ ﺍﻟﻘﺭﻴﺒﺔ ﻤﻥ ﺍﻟﺴﻁﺢ ،ﻭﺘﻐﻴﺭ ﺍﻟﻜﺜﻴﺭ ﻤﻥ ﺨﻭﺍﺼﻬﺎ ﺍﻟﻔﻴﺯﻴﺎﺌﻴﺔ ﻭﺍﻟﻜﻴﻤﻴﺎﺌﻴﺔ ﺒﻴﻥ ﻤﺴﺎﻓﺎﺕ ﻗﺼﻴﺭﺓ ﻓﻲ ﺍﻻﺘﺠﺎﻫﻴﻥ ﺍﻷﻓﻘﻲ ﻭﺍﻟﺭﺃﺴﻲ ﻨﺘﻴﺠﺔ ﻟﻌﺩﻡ ﺘﺠﺎﻨﺴﻬﺎ ﻤﻤﺎ ﻴﺅﺩﻱ ﺇﻟﻰ ﺤﺩﻭﺙ ﺍﻟﻌﺩﻴﺩ ﻤﻥ ﺍﻟﻤﺸﺎﻜل ﺍﻟﻬﻨﺩﺴﻴﺔ ﻟﻤﺎ ﻴﻘﺎﻡ ﻋﻠﻴﻬﺎ ﻤﻥ ﻤﻨﺸﺂﺕ ﻭﻁﺭﻕ .ﺇﻥ ﻤﻥ ﺍﻟﻤﻤﻜﻥ ﺘﻘﺴﻴﻡ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﺒﺸﻜل ﻋﺎﻡ ﺇﻟﻰ ﻨﻭﻋﻴﻥ ﺭﺌﻴﺴﻴﻥ ﻫﻤﺎ :ﺍﻟﺴﺒﺨﺔ ﺍﻟﺴﺎﺤﻠﻴﺔ ﺍﻟﺘﻲ ﺘﻭﺠﺩ ﻋﻠﻰ ﺍﻟﺸﻭﺍﻁﺊ ﺤﻴﺙ ﺘﻜﻭﻥ ﻤﺤﺩﻭﺩﺓ ﻋﺎﺩﺓ ﺒﺨﻠﻴﺞ ﺃﻭ ﺒﺤﺭ ،ﻭﻫﺫﺍ ﺍﻟﻨﻭﻉ ﻴﻭﺠﺩ ﻓﻲ ﺍﻟﻤﻨﻁﻘﺔ ﺍﻟﺸﺭﻗﻴﺔ ﺤﻭل ﺍﻟﺨﻠﻴﺞ ﺍﻟﻌﺭﺒﻲ ﻭﻓﻲ ﺍﻟﻤﻨﻁﻘﺔ ﺍﻟﻐﺭﺒﻴﺔ ﺤﻭل ﺍﻟﺒﺤﺭ ﺍﻷﺤﻤﺭ؛ ﻭﺍﻟﺴﺒﺨﺔ ﺍﻟﻘﺎﺭﻴﺔ )ﺍﻟﺩﺍﺨﻠﻴﺔ( ﺍﻟﺘﻲ ﺘﻐﻁﻲ ﻤﻨﺨﻔﻀﺎﺕ ﻗﺎﺭﻴﺔ ﻤﺴﻁﺤﺔ ﺩﺍﺨل ﺍﻟﻴﺎﺒﺴﺔ ﺒﻌﻴﺩﹰﺍ ﻋﻥ ﺍﻟﺸﻭﺍﻁﺊ ﺍﻟﺒﺤﺭﻴﺔ ﻭﺘﻭﺠﺩ ﻓﻲ
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ﻋﺒﺩﺍﷲ ﺒﻥ ﺇﺒﺭﺍﻫﻴﻡ ﺍﻟﻤﻬﻴﺩﺏ
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ﻭﺍﺩﻱ ﺍﻟﺴﺭﺤﺎﻥ ﻓﻲ ﺍﻟﻤﻨﻁﻘﺔ ﺍﻟﺸﻤﺎﻟﻴﺔ ﻤﻥ ﺍﻟﻤﻤﻠﻜﺔ ،ﻭﻓﻲ ﻤﻨﻁﻘﺔ ﺍﻟﻘﺼﻴﻡ ﻭﺍﻟﺭﺒﻊ ﺍﻟﺨﺎﻟﻲ .ﻫﺫﺍ ﺍﻟﺒﺤﺙ ﻴﻌﻁﻲ ﻨﺒﺫﺓ ﻋﻥ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻭﺘﻭﺯﻴﻌﻬﺎ ﻓﻲ ﺍﻟﻌﺎﻟﻡ ﻭﺃﻨﻭﺍﻋﻬﺎ ،ﻭﺃﻫﻡ ﺍﻟﻌﻭﺍﻤل ﺍﻟﻤﺅﺜﺭﺓ ﻓﻲ ﺘﻜﻭﻴﻨﻬﺎ .ﻜﻤﺎ ﻴﺒﻴﻥ ﺃﻤﺎﻜﻥ ﻭﺠﻭﺩ ﻫﺫﻩ ﺍﻟﺘﺭﺒﺔ ﻓﻲ ﺍﻟﻤﻤﻠﻜﺔ ﺍﻟﻌﺭﺒﻴﺔ ﺍﻟﺴﻌﻭﺩﻴﺔ ،ﻭﺨﻭﺍﺼﻬﺎ ﺍﻟﺠﻴﻭﺘﻜﻨﻴﻜﻴﺔ ﻭﺍﻟﻜﻴﻤﻴﺎﺌﻴﺔ ﻓﻲ ﻜل ﻤﻥ ﺍﻟﻤﻨﻁﻘﺔ ﺍﻟﺸﺭﻗﻴﺔ ،ﻭﺠﻴﺯﺍﻥ ﻭﺠﺩﺓ ﻭﺃﺒﺤﺭ ﻭﺍﻟﻠﻴﺙ ﻓﻲ ﺍﻟﻤﻨﻁﻘﺔ ﺍﻟﻐﺭﺒﻴﺔ .ﻭﻓﻲ ﺍﻟﺨﺘﺎﻡ ﻴﺴﺘﻌﺭﺽ ﻫﺫﺍ ﺍﻟﺒﺤﺙ ﺃﻫﻡ ﻁﺭﻕ ﻤﻌﺎﻟﺠﺔ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻭﻨﺘﺎﺌﺞ ﺘﻁﺒﻴﻕ ﺒﻌﺽ ﻫﺫﻩ ﺍﻟﻁﺭﻕ ﻋﻠﻰ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺒﻌﺽ ﻤﻨﺎﻁﻕ ﻭﺠﻭﺩﻫﺎ.
-1ﻤﻘﺩﻤﺔ ل ل ﻋﺎ ٍ ﻴﻁﻠﻕ ﻟﻔﻅ )ﺴﺒﺨﺔ( ﻋﻠﻰ ﺍﻷﺭﺍﻀﻲ ﺍﻟﻤﻨﺨﻔﻀﺔ ﻭﺍﻟﻤﺴﺘﻭﻴﺔ ﺍﻟﻤﺘﻌﺭﻀﺔ ﻟﻤﻌﺩ ٍ ﻤﻥ ﺘﺒﺨﺭ ﺍﻟﻤﻴﺎﻩ] .[1ﻭﺘﻌﺭﻑ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﺒﺄﻨﻬﺎ ﺍﻟﺘﺭﺒﺔ ﺍﻟﻐﻨﻴﺔ ﺒﺎﻷﻤﻼﺡ ﻨﺘﻴﺠﺔ ﺘﺒﺨﺭ ﻤﺤﺘﻭﺍﻫﺎ ﺍﻟﻤﺎﺌﻲ ﻤﺨﻠﻔﹰﺎ ﻭﺭﺍﺀﻩ ﺍﻷﻤﻼﺡ ﺍﻟﻤﺨﺘﻠﻔﺔ ﺒﺘﺭﺍﻜﻴﺒﻬﺎ ﺍﻟﻜﻴﻤﻴﺎﺌﻴﺔ ﺍﻟﺘﻲ ﺘﺸﻜل ﻓﻲ ﺍﻟﻨﻬﺎﻴﺔ ﻁﺒﻘﺔ ﻤﻠﺤﻴﺔ ﺘﺸﻜل ﺍﻟﻘﺸﺭﺓ ﺍﻟﺼﻠﺒﺔ ﻟﻠﺴﺒﺨﺔ .ﻭﻴﺘﻔﺎﻭﺕ ﺴﻤﻙ ﻁﺒﻘﺔ ﺍﻷﻤﻼﺡ ﺤﺴﺏ ﺍﻟﻅﺭﻭﻑ ﺍﻟﺩﺍﺨﻠﻴﺔ ﻭﺍﻟﺨﺎﺭﺠﻴﺔ ﺍﻟﻤﺅﺜﺭﺓ ﻓﻲ ﺘﻜﻭﻴﻥ ﺍﻟﺴﺒﺨﺔ ﻭﺍﻟﺘﻲ ﻤﻥ ﺃﻫﻤﻬﺎ ﺍﺨﺘﻼﻑ ﺩﺭﺠﺔ ﺍﻟﺤﺭﺍﺭﺓ ،ﻭﺍﻟﺭﻁﻭﺒﺔ ،ﻭﻤﻌﺩل ﺴﻘﻭﻁ ﺍﻷﻤﻁﺎﺭ ،ﻭﺩﺭﺠﺔ ﻤﻠﻭﺤﺔ ﺍﻟﺴﺒﺨﺔ ،ﻭﻋﻤﻕ ﻤﺴﺘﻭﻯ ﻤﻨﺴﻭﺏ ﺍﻟﻤﻴﺎﻩ ﺍﻟﺠﻭﻓﻴﺔ .ﻭﺘﻭﺠﺩ ﻁﺒﻘﺔ ﺍﻷﻤﻼﺡ ﺍﻟﺼﻠﺒﺔ ﻋﺎﺩﺓ ﻓﻭﻕ ﻁﺒﻘﺎﺕ ﻤﻥ ﺍﻟﺭﻤﺎل ﺃﻭ ﻤﻥ ﺍﻟﻁﻤﻲ ﺃﻭ ﻤﻨﻬﻤﺎ ﻤﻌﹰﺎ .ﻭﺘﺘﻜﻭﻥ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻋﺎﺩﺓ ﻤﻥ ﻁﺒﻘﺔ ﺃﻭ ﻋﺩﺓ ﻁﺒﻘﺎﺕ ﻤﻥ ﺭﺴﻭﺒﻴﺎﺕ ﻏﻴﺭ ﻤﺘﺠﺎﻨﺴﺔ ﻭﻏﻴﺭ ﻤﻨﻀﻐﻁﺔ ،ﺘﻜﻭﻥ ﻏﺎﻟﺒﹰﺎ ﻤﻥ ﺍﻟﺭﻤﺎل ﺍﻟﻐﻴﺭ ﻤﺘﻤﺎﺴﻜﺔ ﺫﺍﺕ ﺍﻟﻤﺴﺎﻤﻴﺔ ﻭﺍﻟﻨﻔﺎﺫﻴﺔ ﺍﻟﻌﺎﻟﻴﺘﻴﻥ ﺍﻟﻠﺘﻴﻥ ﺘﺴﻤﺤﺎﻥ ﺒﻤﺭﻭﺭ ﺍﻟﻤﻴﺎﻩ ﺍﻟﺠﻭﻓﻴﺔ ﺇﻟﻰ ﺴﻁﺢ ﺍﻟﺴﺒﺨﺔ ﻤﻤﺎ ﻴﺅﺩﻱ ﺇﻟﻰ ﺯﻴﺎﺩﺓ ﻤﻠﻭﺤﺔ ﺘﻠﻙ ﺍﻟﻤﻴﺎﻩ ﻭﺒﺎﻟﺘﺎﻟﻲ ﺘﺒﻠﻭﺭ ﺍﻟﻤﻌﺎﺩﻥ ﺍﻟﺘﺒﺨﺭﻴﺔ ﻤﻜﻭﻨﺔ ﺍﻟﺴﻁﺢ ﺍﻟﺨﺎﺭﺠﻲ ﻟﻠﺴﺒﺨﺔ ﺍﻟﻤﺘﻤﺎﺴﻙ ﻨﺴﺒﻴﹰﺎ ﻭﺍﻟﺫﻱ ﻴﻔﻘﺩ ﺘﻤﺎﺴﻜﻪ ﻭﻗﻭﺘﻪ ﻋﻨﺩ ﻭﺼﻭل ﺍﻟﻤﺎﺀ ﺇﻟﻴﻪ].[1 ﻭﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﺘﻭﺠﺩ ﻓﻲ ﺃﻤﺎﻜﻥ ﻋﺩﻴﺩﺓ ﻤﻥ ﺩﻭل ﺍﻟﻌﺎﻟﻡ ،ﻭﺨﺎﺼﺔ ﻓﻲ ﺍﻟﻤﻨﺎﻁﻕ ﺍﻟﺤﺎﺭﺓ ﻭﺍﻟﺠﺎﻓﺔ ﺫﺍﺕ ﺍﻟﻤﻨﺎﺥ ﺍﻟﻤﺩﺍﺭﻱ ،ﺤﻴﺙ ﺘﻨﺘﺸﺭ ﻓﻲ ﺍﻟﻭﻁﻥ ﺍﻟﻌﺭﺒﻲ ﻜﺩﻭل ﺍﻟﺨﻠﻴﺞ ﺍﻟﻌﺭﺒﻲ ] ، [4،3،2ﻭﺩﻭل ﺸﻤﺎل ﺃﻓﺭﻴﻘﻴﺎ ] ، [6،5ﻭﺍﻟﺴﻭﺩﺍﻥ ] ،[1ﻭﻜﺫﻟﻙ ﻓﻲ
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ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺍﻟﻤﻤﻠﻜﺔ ﺍﻟﻌﺭﺒﻴﺔ ﺍﻟﺴﻌﻭﺩﻴﺔ ....
ﺍﻟﻤﻜﺴﻴﻙ] ،[1ﻭﺃﺴﺘﺭﺍﻟﻴﺎ] ، [7ﻭﺍﻟﻭﻻﻴﺎﺕ ﺍﻟﻤﺘﺤﺩﺓ ﺍﻷﻤﺭﻴﻜﻴﺔ ] .[9،8ﻜﻤﺎ ﺘﻨﺘﺸﺭ ﻫﺫﻩ ﺍﻟﺘﺭﺒﺔ ﻓﻲ ﺍﻟﻤﻨﺎﻁﻕ ﺍﻟﺠﺎﻓﺔ ﻭﺸﺒﻪ ﺍﻟﺠﺎﻓﺔ ،ﻭﺘﻐﻁﻲ ﻤﺎ ﻴﻘﺎﺭﺏ ﻤﻥ %30ﻤﻥ ﻤﺴﺎﺤﺔ ﺍﻟﻴﺎﺒﺴﺔ ﻋﻠﻰ ﺍﻟﻜﺭﺓ ﺍﻷﺭﻀﻴﺔ ] .[1ﺍﻟﺸﻜل ) (1ﻴﻭﻀﺢ ﺘﻭﺯﻴﻊ ﻤﻨﺎﻁﻕ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺍﻟﻌﺎﻟﻡ. ﺇﻥ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﺘﺘﻤﻴﺯ ﺒﻌﺩﺓ ﺼﻔﺎﺕ ﻤﻥ ﺃﻫﻤﻬﺎ (1) :ﻤﻠﻭﺤﺔ ﻤﻴﺎﻫﻬﺎ ﺍﻟﺠﻭﻓﻴﺔ ﺍﻟﻘﺭﻴﺒﺔ ﻤﻥ ﺴﻁﺢ ﺍﻷﺭﺽ ) (2ﺍﻟﻁﺒﻘﺎﺕ ﺍﻟﻤﺘﻌﺎﻗﺒﺔ ﻤﻥ ﺍﻟﺘﺭﺒﺔ ﻭﺍﻟﻤﻠﺢ ﺫﺍﺕ ﺴﻤﺎﻜﺎﺕ ﻤﺨﺘﻠﻔﺔ ) (3ﻋﺩﻡ ﺘﺠﺎﻨﺴﻬﺎ ﻭﺘﻐﻴﺭ ﺨﻭﺍﺼﻬﺎ ﺍﻟﻔﻴﺯﻴﺎﺌﻴﺔ ﻭﺍﻟﻜﻴﻤﻴﺎﺌﻴﺔ ﻀﻤﻥ ﻤﺴﺎﻓﺎﺕ ﻗﺼﻴﺭﺓ ﺭﺍﺴﻴﺎ ﻭﺃﻓﻘﻴﺎ ) (4ﻗﻠﺔ ﻜﺜﺎﻓﺘﻬﺎ ﻭﻀﻌﻑ ﻗﺩﺭﺘﻬﺎ ﺍﻟﺘﺤﻤﻴﻠﻴﺔ ﻓﻲ ﺤﺎﻟﺘﻬﺎ ﺍﻟﻁﺒﻴﻌﻴﺔ ،ﺤﻴﺙ ﺘﻌﺘﻤﺩ ﻗﻭﺓ ﺘﺤﻤل ﺴﻁﺢ ﺍﻟﺴﺒﺨﺔ ﻋﻠﻰ ﺩﺭﺠﺔ ﺘﺒﻠﻠﻬﺎ ﺒﺎﻟﻤﺎﺀ ،ﻓﺎﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﺍﻟﺠﺎﻓﺔ ﻗﺩ ﺘﺘﺤﻤل ﻭﺯﻥ ﺴﻴﺎﺭﺓ ﻤﺘﻭﺴﻁﺔ ﺍﻟﺤﺠﻡ ﻤﺜﻼﹰ ،ﻭﻟﻜﻨﻬﺎ ﺘﻔﻘﺩ ﻗﺩﺭﺘﻬﺎ ﺍﻟﺘﺤﻤﻴﻠﻴﺔ ـ ﺒﺤﻴﺙ ﻻ ﺘﺴﺘﻁﻴﻊ ﺘﺤﻤل ﻭﺯﻥ ﺇﻨﺴﺎﻥ ـ ﺒﻤﺠﺭﺩ ﺘﺒﻠﻠﻬﺎ ﻭﻭﺼﻭل ﺍﻟﻤﺎﺀ
ﻋﺒﺩﺍﷲ ﺒﻥ ﺇﺒﺭﺍﻫﻴﻡ ﺍﻟﻤﻬﻴﺩﺏ
32
ﺇﻟﻴﻬﺎ ،ﺤﻴﺙ ﻴﻌﻤل ﺍﻟﻤﺎﺀ ﻋﻠﻰ ﺇﺫﺍﺒﺔ ﺍﻟﻤﻭﺍﺩ ﺍﻟﻤﻠﺤﻴﺔ ﺍﻟﺘﻲ ﺘﺭﺒﻁ ﺒﻴﻥ ﺤﺒﻴﺒﺎﺘﻬﺎ .ﻭﻗﺩ ﺘﺴﺒﺒﺕ ﻫﺫﻩ ﺍﻟﺼﻔﺎﺕ ﻓﻲ ﺤﺩﻭﺙ ﻤﺸﺎﻜل ﻫﻨﺩﺴﻴﺔ ﻋﺩﻴﺩﺓ ﻟﻠﻤﻨﺸﺂﺕ ﻭﺍﻟﻁﺭﻕ ﺍﻟﻤﻘﺎﻤﺔ ﻋﻠﻴﻬﺎ ،ﻟﻘﺩ ﺘﻡ ﺒﺎﻟﻔﻌل ﺤﺩﻭﺙ ﻋﺩﺩ ﻤﻥ ﺍﻟﻤﺸﺎﻜل ﺍﻟﺘﻲ ﺘﺸﻤل ﺍﻟﺘﺸﻘﻕ ﻭﺍﻟﺘﺨﺩﻴﺩ ﻭﺘﺸﻜﻴل ﺍﻟﺤﻔﺭ ﻓﻲ ﺍﻟﻁﺭﻕ ﺍﻟﻌﺎﻤﺔ ﻓﻲ ﺍﻟﻤﻨﻁﻘﺔ ﺍﻟﺸﺭﻗﻴﺔ ﺍﻟﻤﻨﺸﺄﺓ ﻓﻭﻕ ﻁﺒﻘﺎﺕ ﻤﻥ
ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ] .[10ﻜﻤﺎ ﺘﻡ ﺭﺼﺩ ﺍﻟﻜﺜﻴﺭ ﻤﻥ ﺍﻷﺒﻨﻴﺔ ﺍﻟﺨﺭﺴﺎﻨﻴﺔ ﺍﻟﺘﻲ ﻅﻬﺭﺕ ﻓﻴﻬﺎ ﺘﺼﺩﻋﺎﺕ ﻭﺘﺸﻘﻘﺎﺕ ﻓﻲ ﻜل ﻤﻥ ﺠﻴﺯﺍﻥ
][11
ﻭﺍﻟﻤﻨﻁﻘﺔ ﺍﻟﺸﺭﻗﻴﺔ].[2
2ـ ﺃﻨﻭﺍﻉ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻟﻠﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﺃﺴﻤﺎﺀ ﻤﺤﻠﻴﺔ ﻋﺩﻴﺩﺓ ﻓﻲ ﻤﻨﺎﻁﻕ ﺘﻜﻭﻨﻬﺎ ﻓﻲ ﺍﻟﻌﺎﻟﻡ ﻨﺘﻴﺠﺔ ﻻﺨﺘﻼﻑ ﻤﻌﺩل ﺘﺒﺨﺭ ﺍﻟﻤﻴﺎﻩ ﺍﻟﻤﺎﻟﺤﺔ ﻤﻥ ﺍﻟﺘﺭﺒﺔ ،ﻭﻗﺩ ﺘﻡ ﺤﺼﺭ ﻤﻌﻅﻤﻬﺎ ﻓﻲ ﻤﺭﺠﻊ ] . [12ﻫﺫﻩ ﺍﻷﺴﻤﺎﺀ ﻤﺘﻌﺩﺩﺓ ﻭﻏﻴﺭ ﻤﺘﻔﻕ ﻋﻠﻴﻬﺎ ﺤﻴﺙ ﺘﺨﺘﻠﻑ ﻤﻥ ﺒﻠﺩ ﺇﻟﻰ ﺁﺨﺭ ﻤﻤﺎ ﻴﺴﺒﺏ ﻋـﺩﻡ ﻭﻀﻭﺡ ﻭﺍﺨﺘﻼﻑ ﻓﻲ ﻭﺼﻔﻬﺎ .ﻭﻟﻘﺩ ﺘﻡ ﺘﺒﺴﻴﻁ ﻫﺫﻩ ﺍﻷﺴﻤﺎﺀ ﻭﺍﺨﺘﺼﺎﺭﻫﺎ ﻤﻥ ﺃﺠل ﺍﻻﺴﺘﺨﺩﺍﻤﺎﺕ ﺍﻟﻬﻨﺩﺴﻴﺔ ﺇﻟﻰ ﺃﺭﺒﻌﺔ ﺃﻨﻭﺍﻉ] [13ﻫﻲ -1 :ﺴـﺒﺨﺔ -2 Sabkhaﻗـﺎﻉ -3 Playaﻗﺎﻉ ﻤﻠﺤﻴﺔ -4 Salt Playaﻤﻼﺤﺔ Salinaﻜﻤﺎ ﻫﻭ ﻤﻭﻀﺢ ﻓﻲ ﺸﻜل ) .(2ﻭﺘﺤﺘﻭﻱ ﻤﻴﺎﻩ ﺍﻟﺒﺤﻴﺭﺓ ﺍﻟﻤﺅﻗﺘﺔ ﻓﻲ ﺍﻟﻘﺎﻉ ﺍﻟﻤﻠﺤﻴﺔ ﻋﻠﻰ ﺍﻷﻤﻼﺡ ﻭﺒﺎﻟﺘﺎﻟﻲ ﺘﺘﻜﻭﻥ ﺍﻟﻘﺸﺭﺓ ﺍﻟﻤﻠﺤﻴﺔ ﺒﻌﺩ ﺘﺒﺨﺭ ﻫﺫﻩ ﺍﻟﻤﻴﺎﻩ .ﺃﻤﺎ ﺒﺎﻟﻨﺴﺒﺔ ﻟﻠﻘﺎﻉ ﻓﺈﻥ ﻤﻴﺎﻩ ﺍﻟﺒﺤﻴﺭﺓ ﺍﻟﻤﺅﻗﺘـﺔ ﻓﻲ ﺍﻟﻐﺎﻟﺏ ﻻ ﺘﺤﺘﻭﻱ ﻋﻠﻰ ﺃﻤﻼﺡ ﻭﺒﺎﻟﺘﺎﻟﻲ ﺘﺘﻜﻭﻥ ﻗﺸﺭﺓ ﻁﻴﻨﻴﺔ ﺃﻭ ﻁﻤﻴﻴﺔ ﺠﺎﻓﺔ ﺒﻌﺩ ﺘﺒﺨﺭ ﺍﻟﻤﻴﺎﻩ )ﺍﻨﻅﺭ ﺸﻜل .(2 ﻭﻴﻤﻜﻥ ﺘﺼﻨﻴﻑ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﺒﺸﻜل ﻋﺎﻡ ﺇﻟﻰ ﻨﻭﻋﻴﻥ ﺭﺌﻴﺴﻴﻥ ﻫﻤـﺎ :ﺍﻟﺴـﺒﺨﺔ ﺍﻟﺴﺎﺤﻠﻴﺔ ﻭﺍﻟﺴﺒﺨﺔ ﺍﻟﻘﺎﺭﻴﺔ. 2ـ 1ﺍﻟﺴﺒﺨﺔ ﺍﻟﺴﺎﺤﻠﻴﺔ ): (Coastal Sabkha ﺘﻨﺘﺞ ﺍﻟﺴﺒﺨﺔ ﺍﻟﺴﺎﺤﻠﻴﺔ ﻤﻥ ﺘﺭﺴﺒﺎﺕ ﺒﺤﺭﻴﺔ ﻭﻗﺎﺭﻴﺔ ﻭﺫﻟﻙ ﺃﺜﻨﺎﺀ ﺘﺭﺍﺠﻊ
33
ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺍﻟﻤﻤﻠﻜﺔ ﺍﻟﻌﺭﺒﻴﺔ ﺍﻟﺴﻌﻭﺩﻴﺔ ....
ﺍﻟﺒﺤﺎﺭ ﻭﺍﻨﺤﺴﺎﺭﻫﺎ ﻋﻥ ﺍﻟﻴﺎﺒﺴﺔ ﺒﺴﺒﺏ ﻅﺎﻫﺭﺓ ﺍﻟﻤﺩ ﻭﺍﻟﺠﺯﺭ .ﻭﺘﺘﻜﻭﻥ ﻫﺫﻩ ﺍﻟﺘﺭﺴﺒﺎﺕ ﻋﺎﺩﺓ ﻤﻥ ﺤﺒﻴﺒﺎﺕ ﺭﻤل ﻨﺎﻋﻤﺔ ﻭﺨﺸﻨﺔ ﻤﻊ ﻨﺴﺒﺔ ﺼﻐﻴﺭﺓ ﻤﻥ ﺍﻟﻁﻤﻲ .ﻭﻋﺎﺩﺓ ﻤﺎ ﺘﺤﺎﻁ ﺍﻟﺴﺒﺨﺔ ﺍﻟﺴﺎﺤﻠﻴﺔ ﺒﺒﺤﻴﺭﺓ ﻤﻨﻔﺼﻠﺔ ﻤﻥ ﺠﻬﺔ ﺍﻟﺒﺤﺭ ﻭ ﺒﺼﺤﺭﺍﺀ ﻤﻥ ﺍﻟﺠﻬﺔ ﺍﻷﺨﺭﻯ ،ﻭﺍﻟﺴﺒﺨﺔ ﺍﻟﺴﺎﺤﻠﻴﺔ ﻤﺴﻁﺤـﺔ ﺘﻘﺭﻴﺒًﺎ ﻭﻴﻨﺤـﺩﺭ ﺴﻁﺤﻬـﺎ ﺍﻨﺤﺩﺍﺭًﺍ ﺒﺴﻴﻁﹰﺎ
ﻋﺒﺩﺍﷲ ﺒﻥ ﺇﺒﺭﺍﻫﻴﻡ ﺍﻟﻤﻬﻴﺩﺏ
34
ﺒﺎﺘﺠﺎﻩ ﺍﻟﺒﺤﺭ .ﻭﺘﺘﻜﻭﻥ ﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﺍﻟﺴﺎﺤﻠﻴﺔ ﻤﻥ ﻋﺩﺓ ﻤﻌﺎﺩﻥ ﺃﻫﻤﻬﺎ ﺍﻷﺭﺍﺠﻭﻨﺎﻴﺕ CaCO3ﻭﺍﻟﻜﺎﻟﺴﺎﻴﺕ CaCO3ﻭﺍﻟﺠﺒﺱ CaSO4.2H2Oﻭﺍﻟﺩﻭﻟﻭﻤﺎﻴﺕ . Ca Mg (CO3)2 ﻭﻴﻭﻀﺢ ﺸﻜل ) (3ﻤﻘﻁﻌﺎ ﻋﺭﻀﻴﺎ ﻟﻠﺴﺒﺨﺔ ﺍﻟﺴﺎﺤﻠﻴﺔ ﻭﺘﺭﻜﻴﺒﻬﺎ ﺍﻟﺩﺍﺨﻠﻲ ،ﺃﻤﺎ ﺸﻜل ) (4ﻓﻴﻭﻀﺢ ﻤﻘﻁﻊ ﻋﺭﻀﻲ ﻓﻲ ﺴﺒﺨﺔ ﺭﻤل ﺍﻟﻜﻭﺍﺭﺘﺯ ،ﺤﻴﺙ ﻴﺒﻴﻥ ﻫﺫﺍ ﺍﻟﺸﻜل ﻜﻴﻔﻴﺔ ﺘﻜﻭﻥ ﺴﺒﺨﺔ ﺍﻟﻜﻭﺍﺭﺘﺯ ﻭﺫﻟﻙ ﻤﻥ ﺨﻼل ﻨﺯﻭﺡ ﺍﻟﺭﻤﺎل ﺍﻟﻤﺤﻤﻭﻟﺔ ﺒﻭﺍﺴﻁﺔ ﺍﻟﺭﻴﺎﺡ ﺒﺎﺘﺠﺎﻩ ﺍﻟﺒﺤﺭ ﻭﺘﻐﻁﻴﺘﻬﺎ ﻟﺘﺭﺴﺒﺎﺕ ﻜﺭﺒﻭﻨﻴﺔ ﺒﺸﻜل ﺘﺩﺭﻴﺠﻲ ﻟﺘﺸﻜل ﻓﻲ ][1
35
ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺍﻟﻤﻤﻠﻜﺔ ﺍﻟﻌﺭﺒﻴﺔ ﺍﻟﺴﻌﻭﺩﻴﺔ ....
ﺍﻟﻨﻬﺎﻴﺔ ﺴﺒﺨﺔ ﺭﻤل ﺍﻟﻜﻭﺍﺭﺘﺯ] .[14ﺇﻥ ﻫﺫﺍﻥ ﺍﻟﺸﻜﻼﻥ ﻴﺒﻴﻨﺎﻥ ﺒﻌﺽ ﺼﻔﺎﺕ ﺍﻟﺴﺒﺨﺔ ﺍﻟﺴﺎﺤﻠﻴﺔ ﻭﺍﻟﺘﻲ ﻤﻥ ﺃﻫﻤﻬﺎ -1 :ﻭﺠﻭﺩ ﺍﻟﺤﺎﺠﺯ ﺍﻟﻤﻜﻭﻥ ﻤﻥ ﺍﻟﻜﺜﺒﺎﻥ ﺍﻟﺭﻤﻠﻴﺔ ﻤﻥ ﺠﻬﺘﻲ ﺍﻟﺒﺤﺭ ﻭﺍﻟﻴﺎﺒﺴﺔ؛ -2ﺃﻥ ﺍﻟﺴﺒﺨﺔ ﺍﻟﺴﺎﺤﻠﻴﺔ ﺘﻜﻭﻥ ﻤﺴﻁﺤﺔ ﺘﻘﺭﻴﺒﺎ ﻭﻴﻨﺤﺩﺭ ﺴﻁﺤﻬﺎ ﺍﻨﺤﺩﺍﺭﺍ ﺒﺴﻴﻁﺎ ﺒﺎﺘﺠﺎﻩ ﺍﻟﺒﺤﺭ؛ -3ﻗﺭﺏ ﻤﻨﺴﻭﺏ ﺍﻟﻤﻴﺎﻩ ﺍﻟﺠﻭﻓﻴﺔ ﻤﻥ ﺴﻁﺢ ﺍﻟﺴﺒﺨﺔ ﺤﻴﺙ ﻻ ﻴﺘﻌﺩﻯ ﻋﻤﻘﻪ 1.5ﻤﺘﺭﹰﺍ ﻓﻲ ﺍﻟﻐﺎﻟﺏ ].[2
ﻋﺒﺩﺍﷲ ﺒﻥ ﺇﺒﺭﺍﻫﻴﻡ ﺍﻟﻤﻬﻴﺩﺏ
36
2ـ 2ﺍﻟﺴﺒﺨﺔ ﺍﻟﻘﺎﺭﻴﺔ ﺃﻭ ﺍﻟﺩﺍﺨﻠﻴﺔ ): (Continental or Inland Sabkha ﺘﺘﻜﻭﻥ ﺍﻟﺴﺒﺨﺔ ﺍﻟﻘﺎﺭﻴﺔ ﺩﺍﺨل ﺍﻟﻴﺎﺒﺴﺔ ﺒﻌﻴﺩﺍ ﻋﻥ ﺍﻟﺸﻭﺍﻁﺊ ﺍﻟﺒﺤﺭﻴﺔ ﻭﻤﻥ ﺜﻡ ﻓﻼ ﻋﻼﻗﺔ ﻟﻠﺘﺭﺴﺒﺎﺕ ﺍﻟﺒﺤﺭﻴﺔ ﻓﻲ ﺘﻜﻭﻴﻨﻬﺎ ،ﻭﻴﻁﻠﻕ ﺒﻌﺽ ﺍﻟﺒﺎﺤﺜﻴﻥ ] [15ﺍﺴﻡ ﺍﻟﺴﺒﺨﺔ ﻋﻠﻰ ﺍﻟﺴﺒﺨﺔ ﺍﻟﻘﺎﺭﻴﺔ ﻭﺤﺩﻫﺎ ﻭﻴﻁﻠﻕ ﺍﺴﻡ ﺍﻟﻘﺎﻉ ) (playaﻋﻠﻰ ﺍﻟﺴﺒﺨﺔ ﺍﻟﺴﺎﺤﻠﻴﺔ. ﻭﺍﻟﺴﺒﺨﺎﺕ ﺍﻟﻘﺎﺭﻴﺔ ﻋﺒﺎﺭﺓ ﻋﻥ ﺃﺴﻁﺢ ﻤﻨﺨﻔﻀﺔ ﻤﻭﺍﺯﻴﺔ ﻟﺴﻁﺢ ﺍﻟﻤﻴﺎﻩ ﺍﻟﺠﻭﻓﻴﺔ ﺘﻌﻤل ﺍﻟﺭﻴﺎﺡ ﻋﻠﻰ ﺇﺯﺍﻟﺔ ﺍﻟﺤﺒﻴﺒﺎﺕ ﺍﻟﺠﺎﻓﺔ ﺍﻟﺼﻐﻴﺭﺓ ﻤﻨﻬﺎ ﺒﺎﺴﺘﻤﺭﺍﺭ ﺤﺘﻰ ﻴﺼل ﻤﻨﺴﻭﺏ ﻫﺫﻩ ﺍﻷﺴﻁﺢ ﺒﺎﻟﻘﺭﺏ ﻤﻥ ﻤﻨﺴﻭﺏ ﺍﻟﻤﻴﺎﻩ ﺍﻟﺠﻭﻓﻴﺔ] .[1ﻭﺘﺘﺤﺭﻙ ﺍﻟﻤﻴﺎﻩ ﺍﻟﺠﻭﻓﻴﺔ ﺇﻟﻰ ﺃﻋﻠﻰ ﺒﻔﻌل ﺍﻟﺨﺎﺼﻴﺔ ﺍﻟﺸﻌﺭﻴﺔ ﺘﺤﺕ ﺘﺄﺜﻴﺭ ﺍﻟﺘﺒﺨﺭ ﺍﻟﻤﺴﺘﻤﺭ ﻤﻥ ﺍﻟﻘﺎﻉ ،ﻭﺘﺯﺩﺍﺩ ﺩﺭﺠﺔ ﻤﻠﻭﺤﺔ ﺍﻟﻤﻴﺎﻩ ﻓﻲ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﺇﻟﻰ ﺍﻟﺤﺩ ﺍﻟﺫﻱ ﻴﺴﻤﺢ ﺒﺘﺭﺴﻴﺏ ﺍﻷﻤﻼﺡ ﻨﺘﻴﺠﺔ ﻟﺘﺒﺨﺭ ﺍﻟﻤﻴﺎﻩ ﻋﺒﺭ ﺍﻟﺴﻁﺢ ﺍﻟﻌﻠﻭﻱ ﻟﻠﺴﺒﺨﺔ ،ﻭﻟﺫﻟﻙ ﻓﺎﻥ ﺍﻟﻤﻴﺎﻩ ﺍﻟﺠﻭﻓﻴﺔ ﺘﻠﻌﺏ ﺩﻭﺭﺍ ﺃﺴﺎﺴﻴﺎ ﻓﻲ ﺘﻜﻭﻴﻥ ﺍﻟﺴﺒﺨﺔ ﺍﻟﻘﺎﺭﻴﺔ ] .[1ﺇﻥ ﻤﺴﺎﺤﺔ ﺍﻟﺴﺒﺨﺔ ﺍﻟﻘﺎﺭﻴﺔ ﺘﻜﻭﻥ
37
ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺍﻟﻤﻤﻠﻜﺔ ﺍﻟﻌﺭﺒﻴﺔ ﺍﻟﺴﻌﻭﺩﻴﺔ ....
ﻋﺎﺩﺓ ﺃﻗل ﻤﻥ ﻤﺴﺎﺤﺔ ﺍﻟﺴﺒﺨﺔ ﺍﻟﺴﺎﺤﻠﻴﺔ ﻜﻤﺎ ﺃﻥ ﻤﻌﺩل ﺍﻟﺘﺒﺨﺭ ﻓﻲ ﺍﻟﺴﺒﺨﺔ ﺍﻟﻘﺎﺭﻴﺔ ﺃﻋﻠﻰ ﻤﻨﻪ ﻓﻲ ﺍﻟﺴﺒﺨﺔ ﺍﻟﺴﺎﺤﻠﻴﺔ ﻭﺫﻟﻙ ﺒﺴﺒﺏ ﺍﻟﻅﺭﻭﻑ ﺍﻟﻤﻨﺎﺨﻴﺔ .ﻜﻤﺎ ﺃﻥ ﺍﻟﺭﻭﺍﺴﺏ ﺍﻟﺤﺼﻭﻴﺔ ) (gravel sedimentsﺘﻜﻭﻥ ﺃﻜﺜﺭ ﺘﻭﺍﺠﺩﹰﺍ ﻓﻲ ﺍﻟﺴﺒﺨﺔ ﺍﻟﻘﺎﺭﻴﺔ ﻤﻨﻬﺎ ﻓﻲ ﺍﻟﺴﺒﺨﺔ ﺍﻟﺴﺎﺤﻠﻴﺔ .ﻭﻴﻐﻠﺏ ﻋﻠﻰ ﺘﺭﻜﻴﺏ ﺍﻟﺴﺒﺨﺔ ﺍﻟﻘﺎﺭﻴﺔ ﻤﻌﺎﺩﻥ ﺍﻟﺠﺒﺱ ﺍﻟﻤﺎﺌﻴﺔ ،CaSO4.2H2Oﻭﺍﻟﻤﺭﻭ ،SiO2ﻭﺍﻟﻜﺎﻟﺴﺎﻴﺕ ،CaCO3ﻭﻤﻠﺢ ﺍﻟﻁﻌﺎﻡ NaClﺍﻟﺫﻱ ﻴﺘﻜﻭﻥ ﻓﻲ ﺍﻟﻁﺒﻘﺔ ﺍﻟﻌﻠﻭﻴﺔ ﺍﻟﺼﻠﺒﺔ ﻟﻠﺴﺒﺨﺔ].[1
3ـ ﺍﻟﻌﻭﺍﻤل ﺍﻟﻤﺅﺜﺭﺓ ﻓﻲ ﺘﻜﻭﻴﻥ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻴﻭﺠﺩ ﺍﻟﻌﺩﻴﺩ ﻤﻥ ﺍﻟﻌﻭﺍﻤل ﺍﻟﺘﻲ ﺘﺅﺜﺭ ﻓﻲ ﺘﺭﻜﻴﺏ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻭﺨﻭﺍﺼﻬﺎ ﺍﻟﻔﻴﺯﻴﺎﺌﻴﺔ ﻭﺍﻟﻜﻴﻤﻴﺎﺌﻴﺔ ،ﻭﻴﺨﺘﻠﻑ ﺘﺄﺜﻴﺭ ﻫﺫﻩ ﺍﻟﻌﻭﺍﻤل ﺒﺎﺨﺘﻼﻑ ﺍﻟﻅﺭﻭﻑ ﺍﻟﻌﺎﻤﺔ ﻟﻠﺴﺒﺨﺔ .ﻭﻴﻤﻜﻥ ﺘﺼﻨﻴﻑ ﻫﺫﻩ ﺍﻟﻌﻭﺍﻤل ﺇﻟﻰ ﺨﻤﺴﺔ ﻋﻭﺍﻤل ﺭﺌﻴﺴﻴﺔ ﻫﻲ]:[2 3ـ 1ﺍﻟﻌﻭﺍﻤل ﺍﻟﻤﻨﺎﺨﻴﺔ ): (Climatic Factors ﺘﺸﻤل ﺍﻟﻌﻭﺍﻤل ﺍﻟﻤﻨﺎﺨﻴﺔ ﻤﻴﺎﻩ ﺍﻷﻤﻁﺎﺭ ،ﻭﺩﺭﺠﺎﺕ ﺍﻟﺤﺭﺍﺭﺓ ،ﻭﻨﺴﺒﺔ ﺍﻟﺭﻁﻭﺒﺔ، ﻭﺍﻟﺭﻴﺎﺡ ﺍﻟﺴﺎﺌﺩﺓ .ﻭﻤﻥ ﺃﻫﻡ ﺍﻟﻌﻭﺍﻤل ﺍﻟﻤﺅﺜﺭﺓ ﻓﻲ ﺘﻜﻭﻴﻥ ﺍﻟﺴﺒﺨﺔ ﺍﻟﻔﺭﻕ ﺒﻴﻥ ﻜﻤﻴﺔ ﺍﻟﻤﻴﺎﻩ ﺍﻟﻤﺭﺘﻔﻌﺔ ﺇﻟﻰ ﺴﻁﺤﻬﺎ ﺒﻔﻌل ﺍﻟﺨﺎﺼﻴﺔ ﺍﻟﺸﻌﺭﻴﺔ ﻭ ﺒﻴﻥ ﻜﻤﻴﺔ ﺍﻟﻤﻴﺎﻩ ﺍﻟﻤﺘﺒﺨﺭﺓ ﻤﻥ ﻫﺫﺍ ﺍﻟﺴﻁﺢ ﺤﻴﺙ ﻴﻌﺘﻤﺩ ﺫﻟﻙ ﻋﻠﻰ ﺍﻟﻅﺭﻭﻑ ﺍﻟﻤﻨﺎﺨﻴﺔ ﻟﻤﻨﻁﻘﺔ ﺍﻟﺴﺒﺨﺔ .ﻭﺘﻌﺘﺒﺭ ﻤﻴﺎﻩ ﺍﻷﻤﻁﺎﺭ ﺃﺤﺩ ﺍﻟﻤﺼﺎﺩﺭ ﺍﻟﺭﺌﻴﺴﻴﺔ ﺍﻟﺜﻼﺜﺔ ﺍﻟﺘﻲ ﺘﻤﺩ ﺍﻟﺴﺒﺨﺔ ﺒﺎﻟﻤﻴﺎﻩ ﺇﻟﻰ ﺠﺎﻨﺏ ﺍﻟﻤﻴﺎﻩ ﺍﻟﺠﻭﻓﻴﺔ ﻭﻤﻴﺎﻩ ﺍﻟﺒﺤﺎﺭ ﺍﻟﻤﺘﺤﺭﻜﺔ ﺇﻟﻰ ﻤﻨﺎﻁﻕ ﺍﻟﺴﺒﺨﺔ ﺍﻟﺴﺎﺤﻠﻴﺔ .ﻭﺘﺅﺜﺭ ﻤﻴﺎﻩ ﺍﻷﻤﻁﺎﺭ ﻋﻠﻰ ﺍﻟﺴﺒﺨﺔ ﻋﻥ ﻁﺭﻴﻕ ﺇﺫﺍﺒﺔ ﺒﻌﺽ ﺍﻷﻤﻼﺡ ﺍﻟﻤﺘﺭﺴﺒﺔ ﻋﻠﻰ ﺍﻟﺴﻁﺢ ﺒﻔﻌل ﺍﻟﺘﺒﺨﺭ ،ﻜﻤﺎ ﺘﻌﻤل ﻋﻠﻰ ﺘﺨﻔﻴﺽ ﺘﺭﻜﻴﺯ ﻤﻠﻭﺤﺔ ﻤﻴﺎﻩ ﺍﻟﺴﺒﺨﺔ ﺍﻟﻤﺭﻜﺯﺓ ،ﺒﺎﻹﻀﺎﻓﺔ ﺇﻟﻰ ﺭﻓﻌﻬﺎ ﻟﻤﺴﺘﻭﻯ ﺍﻟﻤﻴﺎﻩ ﺍﻟﺠﻭﻓﻴﺔ .ﻭﺘﻠﻌﺏ ﺩﺭﺠﺔ ﺍﻟﺤﺭﺍﺭﺓ ﺩﻭﺭﹰﺍ ﻤﻬﻤﹰﺎ ﻓﻲ ﻋﻤﻠﻴﺔ ﺘﺒﺨﺭ ﺍﻟﻤﻴﺎﻩ ﻤﻥ ﺍﻟﺴﺒﺨﺔ ﻭﺘﺭﺴﻴﺏ ﻤﺨﺘﻠﻑ ﺃﻨﻭﺍﻉ ﺍﻷﻤﻼﺡ ﺍﻟﻤﻭﺠﻭﺩﺓ ﺒﻬﺎ .ﻜﻤﺎ ﺃﻥ ﻨﺴﺒﺔ ﺍﻟﺭﻁﻭﺒﺔ ﺘﺘﺤﻜﻡ ﻓﻲ ﻋﻤﻠﻴﺔ ﺘﺭﺴﻴﺏ ﺍﻟﻤﻌﺎﺩﻥ ﻓﻲ ﻤﻴﺎﻩ ﺍﻟﺴﺒﺨﺔ ﺍﻟﻌﺎﻟﻴﺔ ﺍﻟﻤﻠﻭﺤﺔ،
ﻋﺒﺩﺍﷲ ﺒﻥ ﺇﺒﺭﺍﻫﻴﻡ ﺍﻟﻤﻬﻴﺩﺏ
38
ﺤﻴﺙ ﺘﻜﻭﻥ ﺃﻤﻼﺡ ﺍﻟﻜﺒﺭﻴﺘﺎﺕ ﺍﻟﺭﺍﺴﺏ ﺍﻟﺭﺌﻴﺴﻲ ﻋﻨﺩ ﻨﺴﺒﺔ ﺭﻁﻭﺒﺔ ﻋﺎﻟﻴﺔ %76 ، %95ﺒﻴﻨﻤﺎ ﺘﺘﺭﺴﺏ ﺃﻤﻼﺡ ﺍﻟﺼﻭﺩﻴﻭﻡ ﻭﺍﻟﻜﻠﻭﺭﻴﺩ ﻋﻨﺩ ﻨﺴﺒﺔ ﺭﻁﻭﺒﺔ - %67 .%76ﻭﻴﺘﺭﺴﺏ ﺍﻟﺒﻭﺘﺎﺴﻴﻭﻡ ﻋﻨﺩﻤﺎ ﺘﻘل ﻨﺴﺒﺔ ﺍﻟﺭﻁﻭﺒﺔ ﻋﻥ .[8] %67ﻭﺘﻠﻌﺏ ﺍﻟﺭﻴﺎﺡ ﺍﻟﺴﺎﺌﺩﺓ ﺩﻭﺭﺍ ﻤﻬﻤﹰﺎ ﻓﻲ ﺘﻜﻭﻴﻥ ﺍﻟﺴﺒﺨﺔ ﺍﻟﺭﻤﻠﻴﺔ ﻭﻓﻲ ﺘﺠﻤﻴﻊ ﺍﻟﻜﺜﺒﺎﻥ ﺍﻟﺭﻤﻠﻴﺔ ﻓﻭﻕ ﺴﻁﺢ ﺍﻟﺴﺒﺨﺔ. 3ـ 2ﺍﻟﺘﺭﻜﻴﺏ ﺍﻟﻜﻴﻤﻴﺎﺌﻲ ): (Chemical Composition ﻼ ﺃﺴﺎﺴﻴﹰﺎ ﻓﻲ ﻴﻌﺩ ﺍﻟﺘﺭﻜﻴﺏ ﺍﻟﻜﻴﻤﻴﺎﺌﻲ ﻟﻤﻴﺎﻩ ﺍﻟﺴﺒﺨﺔ ﺍﻟﻌﺎﻟﻴﺔ ﺍﻟﻤﻠﻭﺤﺔ ﻋﺎﻤ ﹰ ﺘﻜﻭﻴﻥ ﺍﻟﺴﺒﺨﺔ .ﻓﻨﺴﺒﺔ ﻤﻠﻭﺤﺔ ﻤﻴﺎﻩ ﺍﻟﺨﻠﻴﺞ ﺍﻟﻌﺭﺒﻲ ﺘﺘﺭﺍﻭﺡ ﺒﻴﻥ %3ﻭ ،%4ﺒﻴﻨﻤﺎ ﺘﺘﺭﺍﻭﺡ ﻨﺴﺒﺔ ﺍﻷﻤﻼﺡ ﻓﻲ ﺍﻟﻤﻴﺎﻩ ﺍﻟﺴﺒﺨﺔ ﺍﻟﻤﻤﺘﺩﺓ ﻋﻠﻰ ﻁﻭل ﺴﺎﺤﻠﻪ ﺒﻴﻥ %37 ﻭ ،%60ﻋﻠﻤﹰﺎ ﺒﺄﻥ ﻤﻴﺎﻩ ﺍﻟﺨﻠﻴﺞ ﺘﻌﺘﺒﺭ ﺍﻟﻤﺼﺩﺭ ﺍﻷﺴﺎﺴﻲ ﻟﻤﻴﺎﻩ ﻫﺫﻩ ﺍﻟﺴﺒﺨﺔ] .[2ﻭﻟﻘﺩ ُﻭﺠﺩ ﺃﻥ ﺘﺭﻜﻴﺯ ﺃﻤﻼﺡ ﺍﻟﺼﻭﺩﻴﻭﻡ ﻭﺍﻟﻜﻠﻭﺭﻴﺩ ﻓﻲ ﻤﻴﺎﻩ ﺍﻟﺴﺒﺨﺔ ﺍﻟﺴﺎﺤﻠﻴﺔ ﻋﻠﻰ ﺸﺎﻁﺊ ﺍﻟﺨﻠﻴﺞ ﺍﻟﻌﺭﺒﻲ ﺤﻭﺍﻟﻲ ﺃﺭﺒﻌـﺔ ﺇﻟﻰ ﺨﻤﺴﺔ ﺃﻀﻌﺎﻑ ﺘﺭﻜﻴﺯﻫﺎ ﻓﻲ ﻤﻴﺎﻩ ﺍﻟﺨﻠﻴﺞ ﺍﻟﻌﺭﺒﻲ].[2 ﺇﻥ ﺍﻟﺘﺭﻜﻴﺏ ﺍﻟﻜﻴﻤﻴﺎﺌﻲ ﻟﻠﺘﺭﺒﺔ ﻨﻔﺴﻬﺎ ﻴﺘﺤﻜﻡ ﻓﻲ ﺨﺼﺎﺌﺹ ﻭﺼﻔﺎﺕ ﺍﻟﺴﺒﺨﺔ ﻋﻤﻭﻤﹰﺎ ،ﺤﻴﺙ ﺘﺘﻜﻭﻥ ﺍﻟﺴﺒﺨﺔ ﻤﻥ ﺍﻟﻁﻤﻲ ﺍﻟﻤﺘﺭﺴﺏ ﺒﻭﺍﺴﻁﺔ ﻋﻤﻠﻴﺎﺕ ﺍﻟﻤﺩ ﻭﺍﻟﺠﺯﺭ ﻭﻨﺸﺎﻁ ﺍﻟﺭﻴﺎﺡ ﺍﻟﺒﺤﺭﻴﺔ ،ﺃﻭ ﺘﺘﻜﻭﻥ ﺍﻟﺴﺒﺨﺔ ﻤﻥ ﺍﻟﺭﻤل ﺍﻟﺠﻴﺭﻱ ﺒﻔﻌل ﺍﻟﺭﻴﺎﺡ ][16 ﺍﻟﺼﺤﺭﺍﻭﻴﺔ ] .[1ﻭﻴﻤﻜﻥ ﺘﻘﺴﻴﻡ ﺍﻟﻤﻌﺎﺩﻥ ﺍﻟﻤﻜﻭﻨﺔ ﻟﻠﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﺇﻟﻰ ﻗﺴﻤﻴﻥ ﻫﻤﺎ : ) (1ﺍﻟﻤﻌﺎﺩﻥ ﺍﻟﻨﺎﺸﺌﺔ ﻤﻥ ﺍﻟﺘﺒﺨﺭ :ﻜﻤﻌﺩﻥ ﺍﻷﺭﺍﺠﻭﻨﺎﻴﺕ ) (CaCO3ﺍﻟﺫﻱ ﻴﺘﺭﺴﺏ ﻓﻲ ﺒﺩﺍﻴﺎﺕ ﺘﺭﻜﻴﺯ ﺍﻟﻤﻴﺎﻩ ﺍﻟﻤﺎﻟﺤﺔ ﻓﻲ ﺭﺴﻭﺒﻴﺎﺕ ﺍﻟﺴﺒﺨﺔ ﻭﻜﺫﻟﻙ ﻋﻠﻰ ﺴﻁﺤﻬﺎ؛ ﻭﻤﻌﺩﻥ ﺍﻟﺠﺒﺱ ) (CaSO4.2H2Oﺍﻟﺫﻱ ﻴﻌﺘﺒﺭ ﺃﻜﺜﺭ ﻤﻌﺎﺩﻥ ﺍﻟﺘﺒﺨﺭ ﺸﻴﻭﻋﹰﺎ ﻓﻲ ﺍﻟﺴﺒﺨﺔ ﻭﻴﺘﻜﻭﻥ ﻜﺒﻠﻭﺭﺍﺕ ﻤﺘﻐﻴﺭﺓ ﺍﻟﺤﺠﻡ ﻭﺍﻟﺸﻜل ﻓﻲ ﺭﺴﻭﺒﻴﺎﺕ ﺍﻟﺴﺒﺨﺔ ﻭﻨﺎﺩﺭﹰﺍ ﻤﺎ ﻴﺘﻜﻭﻥ ﻋﻠﻰ ﺍﻟﺴﻁﺢ؛ ﻭﻤﻌﺩﻥ ﺍﻹﻨﻬﻴﺩﺭﺍﻴﺕ ) (CaSO4ﺍﻟﺫﻱ ﻴﺘﺭﺴﺏ ﺘﺤﺕ ﺴﻁﺢ ﺍﻟﺴﺒﺨﺔ ﻜﺒﻠﻭﺭﺍﺕ ﻤﺨﺘﻠﻔﺔ ﺍﻟﺤﺠﻡ ﻭﺍﻟﺸﻜل؛ ﻭﻤﻌﺩﻥ ﺍﻟﻬﺎﻻﻴﺕ ) (NaClﺍﻟﺫﻱ ﻴﺘﺭﺴﺏ
39
ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺍﻟﻤﻤﻠﻜﺔ ﺍﻟﻌﺭﺒﻴﺔ ﺍﻟﺴﻌﻭﺩﻴﺔ ....
ﻋﻠﻰ ﺍﻟﺴﻁﺢ ﻭﺘﺒﻠﻎ ﺴﻤﺎﻜﺘﻪ ﻋﺩﺓ ﺴﻨﺘﻴﻤﺘﺭﺍﺕ؛ ﻭﻤﻌﺩﻥ ﺍﻟﺴﻠﺴﺘﺎﻴﺕ ) (SrSO4ﺍﻟﺫﻱ ﻴﻌﺘﺒﺭ ﻤﻌﺩﻨﹰﺎ ﺜﺎﻨﻭﻴﹰﺎ ﻴﺭﺘﺒﻁ ﺒﻤﻌﺩﻥ ﺍﻟﺠﺒﺱ ﻭﻜﺫﻟﻙ ﺒﻌﺽ ﺍﻟﻤﻌﺎﺩﻥ ﺍﻟﺜﺎﻨﻭﻴﺔ ﺍﻷﺨﺭﻯ. ) (2ﺍﻟﻤﻌﺎﺩﻥ ﺍﻟﻨﺎﺸﺌﺔ ﻤﻥ ﺍﻟﺘﻔﺎﻋل ﺒﻴﻥ ﻤﻴﺎﻩ ﺍﻟﺴﺒﺨﺔ ﻭﺍﻟﺭﺴﻭﺒﻴﺎﺕ : ﻜﻤﻌﺩﻥ ﺍﻟﺩﻭﻟﻭﻤﺎﻴﺕ ) (Ca Mg (CO3)2ﻭﺍﻟﺫﻱ ﻴﺘﻜﻭﻥ ﻓﻲ ﺍﻟﺭﺴﻭﺒﻴﺎﺕ ﺍﻟﺘﻲ ﺘﺤﺘﻭﻱ ﻋﻠﻰ ﺒﻠﻭﺭﺍﺕ ﻜﺜﻴﺭﺓ ﻤﻥ ﺍﻟﺠﺒﺱ ،ﻓﻌﻨﺩﻤﺎ ﺘﺘﺭﺴﺏ ﻤﻌﺎﺩﻥ ﺍﻟﺠﺒﺱ ﻭﺍﻷﺭﺍﺠﻭﻨﺎﻴﺕ ﻭﺍﻹﻨﻬﻴﺩﺭﺍﻴﺕ ﻓﺈﻥ ﻨﺴﺒﺔ ﺍﻟﻤﻐﻨﺴﻴﻭﻡ ﺇﻟﻰ ﺍﻟﻜﺎﻟﺴﻴﻭﻡ ﻓﻲ ﻤﻴﺎﻩ ﺍﻟﺴﺒﺨﺔ ﺘﺯﺩﺍﺩ ﻭﻋﻨﺩﻤﺎ ﺘﺼل ﻫﺫﻩ ﺍﻟﻨﺴﺒﺔ ﺇﻟﻰ 10ﻴﺘﻜﻭﻥ ﻤﻌﺩﻥ ﺍﻟﺩﻭﻟﻭﻤﺎﻴﺕ ﻤﻥ ﻤﻌﺩﻥ ﺍﻷﺭﺍﺠﻭﻨﺎﻴﺕ].[2 ﻭﻜﺫﻟﻙ ﻤﻌﺩﻥ ﺍﻟﻤﺠﻨﺴﺎﻴﺕ ) (MgCO3ﺍﻟﺫﻱ ﻴﺘﻜﻭﻥ ﻓﻲ ﺍﻟﺭﺴﻭﺒﻴﺎﺕ ﺍﻟﺘﻲ ﻴﻜﻭﻥ ﺘﺭﻜﻴﺯ ﺍﻟﻤﻐﻨﺴﻴﻭﻡ ﻓﻲ ﻤﻴﺎﻩ ﺍﻟﺴﺒﺨﺔ ﻋﺎﻟﻴﹰﺎ ﺤﻴﺙ ﻴﺘﻜﻭﻥ ﻤﻥ ﺘﻔﺎﻋل ﺍﻟﻤﻐﻨﺴﻴﻭﻡ ﻤﻊ ﺍﻟﺩﻭﻟﻭﻤﺎﻴﺕ ﻜﻤﺎ ﻴﻠﻲ: 2MgCO3 + Ca++
Mg++ + Ca Mg (CO3)2
3ـ 3ﺍﻟﻌﻭﺍﻤل ﺍﻟﺠﻴﻭﻤﻭﺭﻓﻭﻟﻭﺠﻴﺔ ):(Geomorphological Factors ﻭﺘﺸﻤل ﺍﻟﻌﻭﺍﻤل ﺍﻟﻤﺘﻌﻠﻘﺔ ﺒﺎﻟﺸﻜل ﺍﻟﻌﺎﻡ ﻟﻸﺭﺽ ﺍﻟﺘﻲ ﺘﻜﻭﻨﺕ ﻋﻠﻴﻬﺎ ﺍﻟﺴﺒﺨﺔ. ﺤﻴﺙ ﺘﺘﺤﻜﻡ ﺩﺭﺠﺔ ﺍﻨﺤﺩﺍﺭ ﺍﻟﺴﻁﺢ ﻓﻲ ﺸﻜل ﺍﻟﺴﺒﺨﺔ ﻭﻤﺴﺎﺤﺔ ﺍﻟﺘﺒﺨﺭ ﺍﻟﺴﻁﺤﻴﺔ، ﻓﻜﻠﻤﺎ ﻗﻠﺕ ﺩﺭﺠﺔ ﺍﻨﺤﺩﺍﺭ ﺍﻟﺴﻁﺢ )ﺃﻱ ﻜﻠﻤﺎ ﺯﺍﺩ ﺍﻟﺴﻁﺢ ﺃﻓﻘﻴﺔ( ،ﻜﻠﻤﺎ ﻜﺒﺭﺕ ﺍﻟﻤﺴﺎﺤﺔ ﺍﻟﺴﻁﺤﻴﺔ ﻟﻠﺘﺒﺨﺭ ﻭﺒﺎﻟﺘﺎﻟﻲ ﺯﺍﺩﺕ ﻤﻌﺩﻻﺕ ﺍﻟﺘﺒﺨﺭ .ﻭﻏﺎﻟﺒﹰﺎ ﻤﺎ ﻴﻜﻭﻥ ﺴﻁﺢ ﺍﻟﺴﺒﺨﺔ ﺍﻟﺴﺎﺤﻠﻴﺔ ﺃﻜﺜﺭ ﺍﻨﺤﺩﺍﺭﹰﺍ ﻤﻨﻪ ﻓﻲ ﺍﻟﺴﺒﺨﺔ ﺍﻟﻘﺎﺭﻴﺔ ،ﻭﻴﺴﺎﻋﺩ ﻗﺭﺏ ﻤﻨﺴﻭﺏ ﺍﻟﻤﻴﺎﻩ ﺍﻟﺠﻭﻓﻴﺔ ﻤﻥ ﺴﻁﺢ ﺍﻟﺴﺒﺨﺔ ﻋﻠﻰ ﺘﺭﺴﻴﺏ ﺍﻟﻤﺯﻴﺩ ﻤﻥ ﺍﻷﻤﻼﺡ ﺍﻟﻨﺎﺘﺠﺔ ﻤﻥ ﻋﻤﻠﻴﺔ ﺍﻟﺘﺒﺨﺭ .ﺇﻥ ﻗﺭﺏ ﺍﻟﺴﺒﺨﺔ ﻤﻥ ﺍﻟﺸﻭﺍﻁﺊ ﺃﻭ ﺒﻌﺩﻫﺎ ﻋﻨﻬﺎ ﻴﺅﺜﺭ ﻓﻲ ﺃﻨﻭﺍﻉ ﺍﻷﻤﻼﺡ ﺍﻟﻤﺘﺭﺴﺒﺔ ﺒﺎﻟﺘﺒﺨﺭ ﺤﻴﺙ ﺘﺤﺘﻭﻱ ﺍﻟﺴﺒﺨﺔ ﺍﻟﻤﺘﺎﺨﻤﺔ ﻟﻠﺴﻭﺍﺤل ﺍﻟﺒﺤﺭﻴﺔ ﻋﻠﻰ ﻤﻌﺩﻥ ﺍﻟﺩﻭﻟﻭﻤﺎﻴﺕ ،ﺒﻴﻨﻤﺎ ﻴﻜﻭﻥ ﺍﻟﺠﺒﺱ ﻭﻤﻠﺢ ﺍﻟﻁﻌﺎﻡ ﻤﻥ ﺍﻟﻤﻌﺎﺩﻥ ﺍﻟﻤﻜﻭﻨﺔ ﻟﻠﺴﺒﺨﺔ ﺍﻟﺘﻲ ﺘﻔﺼﻠﻬﺎ ﺍﻟﻜﺜﺒﺎﻥ ﺍﻟﺭﻤﻠﻴﺔ ﻋﻥ ﻤﻨﺎﻁﻕ ﺍﻟﻤﻴﺎﻩ ﺍﻟﺒﺤﺭﻴﺔ ].[17 3ـ 4ﺍﻟﻌﻭﺍﻤل ﺍﻟﻬﻴﺩﺭﻭﻟﻭﺠﻴﺔ ):(Hydrological Factors
ﻋﺒﺩﺍﷲ ﺒﻥ ﺇﺒﺭﺍﻫﻴﻡ ﺍﻟﻤﻬﻴﺩﺏ
40
ﺘﺘﻁﻠﺏ ﻫﺫﻩ ﺍﻟﻌﻭﺍﻤل ﺒﺫل ﺍﻟﺠﻬﻭﺩ ﻟﺩﺭﺍﺴﺘﻬﺎ ﻷﻨﻬﺎ ﺘﻌﺘﻤﺩ ﻋﻠﻰ ﺩﺭﺍﺴﺔ ﺸﺎﻤﻠﺔ ﻟﺨﺼﺎﺌﺹ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺍﻟﻤﻭﻗﻊ ﻓﻲ ﺍﻻﺘﺠﺎﻩ ﺍﻷﻓﻘﻲ ﺃﻭ ﺍﻻﺘﺠﺎﻩ ﺍﻟﺭﺃﺴﻲ ﺃﻭ ﻜﻠﻴﻬﻤﺎ ﻤﻌ ﹰﺎ .ﻭ‘ﻴﻘﺼﺩ ﺒﻬﺫﻩ ﺍﻟﻌﻭﺍﻤل ﻤﺎ ﻴﺘﻌﻠﻕ ﺒﺎﻟﻤﻴﺎﻩ ﺍﻟﻤﻤﺩﺓ ﻟﻠﺴﺒﺨﺔ ﻭﺼﻔﺎﺘﻬﺎ ﺍﻟﻔﻴﺯﻴﺎﺌﻴﺔ ﻤﺜل ﻤﻴﺎﻩ ﺍﻟﺒﺤﺎﺭ )ﺍﻟﻤﻴﺎﻩ ﺍﻟﺴﻁﺤﻴﺔ( ﺍﻟﺘﻲ ﺘﺨﺘﺹ ﺒﺎﻟﺴﺒﺨﺔ ﺍﻟﺴﺎﺤﻠﻴﺔ، ﻭﺍﻟﻤﻴﺎﻩ ﺍﻟﺠﻭﻓﻴﺔ ﺍﻟﺘﻲ ﻻ ﻴﺯﻴﺩ ﻋﻤﻘﻬﺎ ﻋﺎﺩﺓ ﻓﻲ ﺍﻟﺴﺒﺨـﺔ ﻋﻥ ﺍﻟﻤﺘﺭ ﻭﺍﻟﻨﺼﻑ، ﻭﻤﻌﺩل ﺍﻟﺘﺒﺨﺭ ﺍﻟﺼﺎﻓـﻲ ﺍﻟﺫﻱ ﻴﺒﻠـﻎ ﻤﺘﻭﺴﻁـﻪ 6ﺴﻡ/ﺍﻟﺴﻨﺔ ﻤﻥ ﺍﻟﻤﻴـﺎﻩ ﺍﻟﺠﻭﻓﻴﺔ ﻭ 124ﺴﻡ/ﺍﻟﺴﻨﺔ ﺒﺎﻟﻨﺴﺒﺔ ﻟﻤﻴﺎﻩ ﺍﻟﺨﻠﻴﺞ ﺍﻟﻌﺭﺒﻲ] ،[1ﻭﻨﻔﺎﺫﻴﺔ ﺍﻟﺴﺒﺨﺔ ﺍﻟﺘﻲ ﺘﻌﺘﻤﺩ ﻋﻠﻰ ﺤﺠﻡ ﺍﻟﺤﺒﻴﺒﺎﺕ ﺍﻟﻤﻜﻭﻨﺔ ﻟﻠﺴﺒﺨﺔ ﻭﺩﺭﺠﺔ ﺍﻟﺘﺤﺎﻤﻬﺎ ،ﻭﻋﺎﺩﺓ ﻻ ﺘﺘﻌﺩﻯ ﺴﺭﻋﺔ ﻤﺭﻭﺭ ﺍﻟﻤﻴﺎﻩ ﺍﻟﺠﻭﻓﻴﺔ ﻓﻲ ﺍﻟﺴﺒﺨﺔ ﻋﻥ 6-10x1ﻡ/ﺍﻟﺜﺎﻨﻴﺔ ] .[15ﺇﻥ ﻨﻔﺎﺫﻴﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺍﻟﺤﻘل ﺘﻘﺩﺭ ﺒﺤﻭﺍﻟﻲ 5-10x6ﻡ/ﺍﻟﺜﺎﻨﻴﺔ ﻭﺍﻟﺘﻲ ﺘﻤﺜل ﻏﺎﻟﺒﹰﺎ ﺍﻟﻨﻔﺎﺫﻴﺔ ﻓﻲ ﺍﻻﺘﺠﺎﻩ ﺍﻷﻓﻘﻲ ].[18 3ـ 5ﺍﻟﻌﻭﺍﻤل ﺍﻟﺤﻴﻭﻴﺔ ): ( Biological Factors ﻭﻫﻲ ﺍﻟﻤﻅﺎﻫـﺭ ﺍﻟﺤﻴﺎﺘﻴﺔ ﺍﻟﺘﻲ ﺘﺘﻭﺍﺠﺩ ﻓﻲ ﺍﻟﺴﺒﺨﺔ ﺭﻏﻡ ﻤﻠﻭﺤﺔ ﻤﻴﺎﻫﻬﺎ ﻭﺍﻟﺘﻲ ﻤﻥ ﺃﻫﻤﻬﺎ ﻨﻤﻭ ﺍﻟﻁﺤﺎﻟﺏ ﺍﻟﺘﻲ ﺘﻌﻤل ﻋﻠﻰ ﺘﺭﺍﺒﻁ ﻭﺘﻤﺎﺴﻙ ﺤﺒﻴﺒﺎﺕ ﺍﻟﺴﺒﺨـﺔ ﻭﺒﺎﻟﺘﺎﻟﻲ ﺘﻜﻭﻴﻥ ﺠﺴﻡ ﻤﺘﻤﺎﺴﻙ ﻴﻤﺜل ﺍﻟﻘﺎﻋـﺩﺓ ﺍﻟﺘﻲ ﺘﺘﻜﻭﻥ ﻋﻠﻴﻬـﺎ ﺍﻟﺴﺒﺨﺔ ﺍﻟﺴﺎﺤﻠﻴﺔ .ﻜﻤﺎ ﺘﻁﻠﻕ ﺍﻟﻁﺤﺎﻟﺏ ﻏﺎﺯ ﻜﺒﺭﻴﺘﻴﺩ ﺍﻟﻬﻴﺩﺭﻭﺠﻴﻥ ﻋﻨﺩ ﻤﻭﺘﻬﺎ ﻤﻤﺎ ﻴﺅﺩﻱ ﺇﻟﻰ ﺯﻴﺎﺩﺓ ﺍﻟﻤﺴﺎﻤﻴﺔ ﻭﺍﻟﻨﻔﺎﺫﻴﺔ ﻟﻠﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ .ﺇﻥ ﺘﻭﺍﺠﺩ ﺍﻟﺒﻜﺘﻴﺭﻴﺎ ﺍﻟﻤﻨﺘﺠﺔ ﻟﻠﻜﺒﺭﻴﺕ ﻭﻜﺒﺭﻴﺘﻴﺩ ﺍﻟﻬﻴﺩﺭﻭﺠﻴﻥ ﻴﺴﺎﻋﺩ ﻋﻠﻰ ﺘﺭﺴﻴﺏ ﺒﻌﺽ ﺍﻟﻤﻌﺎﺩﻥ ﺍﻟﻌﺎﻟﻘﺔ ﻓﻲ ﻤﻴﺎﻩ ﺍﻟﺴﺒﺨﺔ ] ،[2ﻭﺘﺄﺜﻴﺭ ﻫﺫﻩ ﺍﻟﻌﻭﺍﻤل ﻋﻠﻰ ﺘﻜﻭﻴﻥ ﺍﻟﺴﺒﺨﺔ ﻤﺤﺩﻭﺩ ﻨﺴﺒﻴﹰﺎ ﻤﻘﺎﺭﻨﺔ ﺒﺎﻟﻌﻭﺍﻤل ﺍﻷﺨﺭﻯ.
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ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺍﻟﻤﻤﻠﻜﺔ ﺍﻟﻌﺭﺒﻴﺔ ﺍﻟﺴﻌﻭﺩﻴﺔ ....
4ـ ﻤﻨﺎﻁﻕ ﻭﺠﻭﺩ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺍﻟﻤﻤﻠﻜﺔ ﺍﻟﻌﺭﺒﻴﺔ ﺍﻟﺴﻌﻭﺩﻴﺔ ﺘﻨﺘﺸﺭ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺍﻟﻤﻤﻠﻜﺔ ﺍﻟﻌﺭﺒﻴﺔ ﺍﻟﺴﻌﻭﺩﻴﺔ ﺤﻭل ﺍﻟﺸﻭﺍﻁﺊ ﺍﻟﻤﻁﻠﺔ ﻋﻠﻰ ﺍﻟﺨﻠﻴﺞ ﺍﻟﻌﺭﺒﻲ ﻭﺍﻟﺒﺤﺭ ﺍﻷﺤﻤﺭ ،ﻜﻤﺎ ﺘﻭﺠﺩ ﻓﻲ ﻤﻨﺎﻁﻕ ﺼﻐﻴﺭﺓ ﺩﺍﺨل ﺍﻟﻤﻤﻠﻜﺔ. ﺤﻴﺙ ﺘﻭﺠﺩ ﻫﺫﻩ ﺍﻟﺘﺭﺒﺔ ﻓﻲ ﻤﻨﺎﻁﻕ ﻤﺘﻌﺩﺩﺓ ﻤﻥ ﺍﻟﻤﻨﻁﻘﺔ ﺍﻟﺸﺭﻗﻴﺔ ﻋﻠﻰ ﺴﺎﺤل ﺍﻟﺨﻠﻴﺞ ﺍﻟﻌﺭﺒﻲ ،ﻭﻓﻲ ﺠﺩﺓ ﻭﺠﻴﺯﺍﻥ ﻭﺃﺒﺤﺭ ﻭﺍﻟﻠﻴﺙ ﻋﻠﻰ ﺴﺎﺤل ﺍﻟﺒﺤﺭ ﺍﻷﺤﻤﺭ، ﻭﺘﻭﺠﺩ ﺃﻴﻀﹰﺎ ﻓﻲ ﻤﻨﻁﻘﺔ ﻭﺍﺩﻱ ﺍﻟﺴﺭﺤﺎﻥ ﻓﻲ ﺍﻟﻤﻨﻁﻘﺔ ﺍﻟﺸﻤﺎﻟﻴﺔ ﻤﻥ ﺍﻟﻤﻤﻠﻜﺔ ﻭﻓﻲ ﻤﺴﺎﺤﺎﺕ ﻗﻠﻴﻠﺔ ﻤﻥ ﻤﻨﻁﻘﺔ ﺍﻟﻘﺼﻴﻡ ﻓﻲ ﻭﺴﻁ ﺍﻟﻤﻤﻠﻜﺔ .ﻭﻴﻭﻀﺢ ﺍﻟﺸﻜل ) (5ﺘﻭﺯﻴﻊ ﻤﻨﺎﻁﻕ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺍﻟﻤﻤﻠﻜﺔ ﺍﻟﻌﺭﺒﻴﺔ ﺍﻟﺴﻌﻭﺩﻴﺔ.
ﻋﺒﺩﺍﷲ ﺒﻥ ﺇﺒﺭﺍﻫﻴﻡ ﺍﻟﻤﻬﻴﺩﺏ
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ﻭﻟﻘﺩ ﺃﺩﻯ ﺍﻟﺘﺴﺎﺭﻉ ﺍﻟﻌﻤﺭﺍﻨﻲ ﻭﺍﻟﻨﺸﺎﻁ ﺍﻹﻨﺸﺎﺌﻲ ﻋﻠﻰ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺍﻟﻤﻤﻠﻜﺔ ﺍﻟﻌﺭﺒﻴﺔ ﺍﻟﺴﻌﻭﺩﻴﺔ ﺇﻟﻰ ﺇﺯﺩﻴﺎﺩ ﻨﺸﺎﻁ ﺍﻻﺴﺘﻜﺸﺎﻓﺎﺕ ﺍﻟﻤﻴﺩﺍﻨﻴﺔ ﻭﺍﻻﺨﺘﺒﺎﺭﺍﺕ ][10،11،14،18،26،2،1 ﺍﻟﻤﻌﻤﻠﻴﺔ ﻟﻬﺫﻩ ﺍﻟﺘﺭﺒﺔ ﺤﻴﺙ ﺘﻡ ﺇﺠﺭﺍﺀ ﺍﻟﻌﺩﻴﺩ ﻤﻥ ﺍﻟﺩﺭﺍﺴﺎﺕ ﻟﻠﺘﻌﺭﻑ ﻋﻠﻰ ﺨﺼﺎﺌﺼﻬﺎ ﻭﺘﻭﻗﻊ ﺴﻠﻭﻜﻬﺎ ﻋﻨﺩ ﺍﺴﺘﺨﺩﺍﻤﻬﺎ ﻜﺄﺴﺎﺱ ﻟﻠﻤﻨﺸﺂﺕ ﺍﻟﻬﻨﺩﺴﻴﺔ .ﻭﻓﻲ ﻫﺫﺍ ﺍﻟﺠﺯﺀ ﻤﻥ ﺍﻟﺒﺤﺙ ﺴﻴﺘﻡ ﺍﺴﺘﻌﺭﺍﺽ ﺃﻤﺎﻜﻥ ﻭﺠﻭﺩ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺍﻟﻤﻤﻠﻜﺔ ﺍﻟﻌﺭﺒﻴﺔ ﺍﻟﺴﻌﻭﺩﻴﺔ ﻭﺍﻟﺨﻭﺍﺹ ﺍﻟﺠﻴﻭﺘﻜﻨﻴﻜﻴﺔ ﻭﺍﻟﻜﻴﻤﻴﺎﺌﻴﺔ ﻟﻜل ﻤﻨﻁﻘﺔ ﻭﻜﺫﻟﻙ ﺃﻫﻡ ﻁﺭﻕ ﺍﻟﻤﻌﺎﻟﺠﺔ ﻟﺘﺭﺒﺔ ﻜل ﻤﻨﻁﻘﺔ ﻭﻓﻘﹰﺎ ﻟﻤﺎ ﻫﻭ ﻤﺘﻭﻓﺭ ﻤﻥ ﻤﻌﻠﻭﻤﺎﺕ ﻓﻲ ﺍﻟﻤﺭﺍﺠﻊ ﺍﻟﻤﺨﺘﻠﻔﺔ. 4ـ 1ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺍﻟﻤﻨﻁﻘﺔ ﺍﻟﺸﺭﻗﻴﺔ: ﺘﻐﻁﻲ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺍﻟﻤﻨﻁﻘﺔ ﺍﻟﺸﺭﻗﻴﺔ ﺤﻭﺍﻟﻲ %15ﻤﻥ ﺍﻟﺸﺭﻴﺤﺔ ﺍﻟﺴﺎﺤﻠﻴﺔ ﺍﻟﻤﻤﺘﺩﺓ ﺒﻌﺭﺽ 40ﻜﻠﻡ ﻭﻁﻭل 350ﻜﻠﻡ ﻤﻥ ﺍﻟﺴﻔﺎﻨﻴﺔ ﻓﻲ ﺍﻟﺸﻤﺎل ﺇﻟﻰ ﺴﻠﻭﻯ ﻓﻲ ﺍﻟﺠﻨﻭﺏ ] .[14ﻭﻴﻭﻀﺢ ﺸﻜل ) (6ﺘﻭﺯﻴﻊ ﻤﻨﺎﻁﻕ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻋﻠﻰ ﻁﻭل ﺍﻟﺴﺎﺤل ﺍﻟﺸﺭﻗﻲ ﻟﻠﻤﻤﻠﻜﺔ ﺍﻟﻌﺭﺒﻴﺔ ﺍﻟﺴﻌﻭﺩﻴﺔ. ﻭﻟﻘﺩ ﺒﻴﻨﺕ ﺍﻟﺩﺭﺍﺴﺎﺕ ﺃﻥ ﻤﺴﺘﻭﻯ ﺴﻁﺢ ﺍﻟﻤﺎﺀ ﻓﻲ ﺍﻟﺨﻠﻴﺞ ﺍﻟﻌﺭﺒﻲ ﻗﺩ ﺍﻨﺨﻔﺽ ﻓﻲ ﺍﻟﻔﺘﺭﺓ ﻤﻥ 4000ﻗﺒل ﺍﻟﻤﻴﻼﺩ ﺇﻟﻰ ﻭﻗﺘﻨﺎ ﺍﻟﺤﺎﻀﺭ ﺒﻤﻘﺩﺍﺭ 2.7ﺇﻟﻰ 2.9ﻤﺘﺭ ﺘﻘﺭﻴﺒﹰﺎ، ﻤﻤﺎ ﻴﻌﻨﻲ ﺃﻥ ﻤﻨﺎﻁﻕ ﺍﻟﺴﺒﺨﺔ ﺍﻟﺤﺎﻟﻴﺔ ﻓﻲ ﺍﻟﻤﻨﻁﻘﺔ ﺍﻟﺸﺭﻗﻴﺔ ﻜﺎﻨﺕ ﺘﻘﻊ ﺘﺤﺕ ﻤﺴﻁﺤﺎﺕ ﻤﺎﺌﻴﺔ ﻀﺤﻠﺔ ﺍﻤﺘﺩﺕ ﺇﻟﻰ ﻤﺎ ﻴﻘﺎﺭﺏ ﺍﻟﻜﻴﻠﻭﻤﺘﺭ ﻋﻠﻰ ﺍﻷﻗل ﻏﺭﺒﻲ ﺍﻟﺨﻁ ﺍﻟﺴﺎﺤﻠﻲ ﺍﻟﺤﺎﻟﻲ ].[1 ﻭﻜﻤﺎ ﺘﻤﺕ ﺍﻹﺸﺎﺭﺓ ﺇﻟﻴﻪ ﺴﺎﺒﻘﹰﺎ ﻓﺈﻥ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﺘﺘﻤﻴﺯ ﺒﺘﻐﻴﺭ ﺨﻭﺍﺼﻬﺎ ﺍﻟﻔﻴﺯﻴﺎﺌﻴﺔ ﻭﺍﻟﻜﻴﻤﻴﺎﺌﻴﺔ ﺒﻴﻥ ﻤﺴﺎﻓﺎﺕ ﻗﺼﻴﺭﺓ ﺭﺃﺴﻴﹰﺎ ﻭﺃﻓﻘﻴﹰﺎ ،ﻭﻴﺒﻴﻥ ﺠﺩﻭل ) (1ﺘﻐﻴﺭ ﺍﻟﺨﻭﺍﺹ ﺍﻟﺠﻴﻭﺘﻜﻨﻴﻜﻴﺔ )ﺍﻟﺤﺩ ﺍﻷﺩﻨﻰ ﻭﺍﻟﺤﺩ ﺍﻷﻋﻠﻰ( ﻟﻠﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺍﻟﻤﻨﻁﻘﺔ ﺍﻟﺸﺭﻗﻴﺔ ﺒﺎﻟﻘﺭﺏ ﻤﻥ ﻤﺩﻴﻨـﺔ ﺍﻟﺠﺒﻴل ﺍﻟﺼﻨﺎﻋﻴﺔ ﺤﻴﺙ ﺘﻡ ﺍﺨﺘﺒﺎﺭ ﺨﻤﺱ ﻭﺨﻤﺴﻭﻥ ﻋﻴﻨﺔ ] .[20ﻭﻴﺘﺒﻴﻥ ﻤﻥ ﻫﺫﺍ ﺍﻟﺠﺩﻭل ﺃﻥ ﻫﻨﺎﻙ ﺘﻔﺎﻭﺘﹰﺎ ﻜﺒﻴﺭﹰﺍ ﻓﻲ ﻨﺴﺒﺔ ﺍﻟﻤﻭﺍﺩ ﺍﻟﻤﺎﺭﺓ
43
ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺍﻟﻤﻤﻠﻜﺔ ﺍﻟﻌﺭﺒﻴﺔ ﺍﻟﺴﻌﻭﺩﻴﺔ ....
ﻤﻥ ﻤﻨﺨل ﺭﻗﻡ (%97 -%18) 200ﻤﻤﺎ ﻴﺩل ﻋﻠﻰ ﺃﻥ ﻨﺴﺒﺔ ﺍﻟﺤﺒﻴﺒﺎﺕ ﺍﻟﺩﻗﻴﻘﺔ )ﺍﻟﻁﻤﻲ ﻭﺍﻟﻁﻴﻥ( ﻤﺘﻔﺎﻭﺘﺔ ﻓﻲ ﻫﺫﻩ ﺍﻟﻌﻴﻨﺎﺕ ﻭﺒﺎﻟﺘﺎﻟﻲ ﻓﺈﻥ ﻗﻴﻡ ﻜل ﻤﻥ ﺤﺩ ﺍﻟﺴﻴﻭﻟﺔ ﻭﻤﻌﻴﺎﺭ ﺍﻟﻠﺩﻭﻨﺔ ﻤﺘﻔﺎﻭﺘﺔ ﻜﺫﻟﻙ .ﻜﻤﺎ ﺃﻥ ﺃﻋﻠﻰ ﻗﻴﻤﺔ ﻟﻌﺩﺩ ﺍﻟﻀﺭﺒﺎﺕ ﻤﻥ ﺍﺨﺘﺒﺎﺭ ﺍﻻﺨﺘﺭﺍﻕ ﺍﻟﻘﻴﺎﺴﻲ ) (SPTﻜﺎﻨﺕ 6ﺤﻴﺙ ﺘﺩل ﻫﺫﻩ ﺍﻟﻘﻴﻤﺔ ﻋﻠﻰ ﻀﻌﻑ ﺘﺤﻤل ﺍﻟﺘﺭﺒﺔ. ﻭﺘﺩل ﻗﻴﻡ ﺍﻟﺘﻤﺎﺴﻙ 0.54ﻜﻴﻠﻭﻨﻴﻭﺘﻥ/ﻡ 2ﻭﺯﺍﻭﻴﺔ ﺍﻻﺤﺘﻜﺎﻙ ﺍﻟﺩﺍﺨﻠﻲ 5 22ﻋﻠﻰ ﻀﻌﻑ ﻤﻘﺎﻭﻤﺔ ﺍﻟﺘﺭﺒﺔ ﻟﻘﻭﻯ ﺍﻟﻘﺹ.
ﻋﺒﺩﺍﷲ ﺒﻥ ﺇﺒﺭﺍﻫﻴﻡ ﺍﻟﻤﻬﻴﺩﺏ
44
ﺠﺩﻭل ) : (1ﺍﻟﺨﻭﺍﺹ ﺍﻟﺠﻴﻭﺘﻜﻨﻴﻜﻴﺔ ﻟﻠﺴﺒﺨﺔ ﻓﻲ ﺍﻟﻤﻨﻁﻘﺔ ﺍﻟﺸﺭﻗﻴﺔ ) 55ﻋﻴﻨﺔ( ﺍﻟﻭﺼﻑ
][20
ﺍﻟﺤﺩ ﺍﻷﻋﻠﻰ
ﺍﻟﺤﺩ ﺍﻷﺩﻨﻰ
97
18
84.6
10
ﺤﺩ ﺍﻟﺴﻴﻭﻟﺔ% ،
84
30
ﻤﻌﻴﺎﺭ ﺍﻟﻠﺩﻭﻨﺔ% ،
39
ﻏﻴﺭ ﻟﺩﻥ
1.89
1.34
2.82
2.51
6
0
0.54
0
22
0
ﻨﺴﺒﺔ ﺍﻟﻔﺭﺍﻏﺎﺕ ﺍﻷﻭﻟﻴﺔ
2.16
1.08
ﻤﻌﺎﻤل ﺍﻻﻨﻀﻐﺎﻁ )(Cc
0.95
0.39
ﺍﻟﻤﻭﺍﺩ ﺍﻟﻤﺎﺭﺓ ﻤﻥ ﻤﻨﺨل ﺭﻗﻡ % ، 200 ﺍﻟﻤﺤﺘﻭﻯ ﺍﻟﻤﺎﺌﻲ ﺍﻟﻁﺒﻴﻌﻲ% ،
ﺍﻟﻜﺜﺎﻓﺔ ﺍﻟﻜﻠﻴﺔ ،ﺠﻡ/ﺴﻡ
3
ﺍﻟﻭﺯﻥ ﺍﻟﻨﻭﻋﻲ ﺍﺨﺘﺒﺎﺭ ﺍﻻﺨﺘﺭﺍﻕ ﺍﻟﻘﻴﺎﺴﻲ ) ،(SPTﻋﺩﺩ ﺍﻟﻀﺭﺒﺎﺕ 300/ﻤﻡ ﺍﻟﺘﻤﺎﺴﻙ )C (kN/m2 ﺯﺍﻭﻴﺔ ﺍﻻﺤﺘﻜﺎﻙ ﺍﻟﺩﺍﺨﻠﻲ )φ (degrees
ﻜﻤﺎ ﺘﺘﻤﻴﺯ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﺃﻴﻀﹰﺎ ﺒﻤﻠﻭﺤﺔ ﻤﻴﺎﻫﻬﺎ ،ﺤﻴﺙ ﻴﺒﻴﻥ ﺠﺩﻭل )(2 ﺍﻟﺘﺭﻜﻴﺏ ﺍﻟﻜﻴﻤﻴﺎﺌﻲ ﻟﻤﻴﺎﻩ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺍﻟﻤﻨﻁﻘﺔ ﺍﻟﺸﺭﻗﻴﺔ ﻤﻘﺎﺭﻨﺔ ﺒﻤﻴﺎﻩ ﺍﻟﺨﻠﻴﺞ ﺍﻟﻌﺭﺒﻲ. ﻭﻴﺘﻀﺢ ﻤﻥ ﻫﺫﺍ ﺍﻟﺠﺩﻭل ﺃﻥ ﺘﺭﻜﻴﺯ ﺍﻷﻴﻭﻨﺎﺕ ﻓﻲ ﻤﻴﺎﻩ ﺍﻟﺴﺒﺨﺔ ﺃﻋﻠﻰ ﻤﻨﻪ ﻓﻲ ﻤﻴﺎﻩ ﺍﻟﺨﻠﻴﺞ ﺍﻟﻌﺭﺒﻲ ﺨﺎﺼﺔ ﺘﺭﻜﻴﺯ ﺍﻟﺼﻭﺩﻴﻭﻡ ﻭﺍﻟﻜﻠﻭﺭﻴﺩ ﻭﺍﻟﺫﻱ ﻴﺒﻠﻎ ﺃﺭﺒﻌﺔ ﺇﻟﻰ ﺨﻤﺴﺔ ﺃﻀﻌﺎﻑ ﺘﺭﻜﻴﺯﻫﺎ ﻓﻲ ﻤﻴﺎﻩ ﺍﻟﺨﻠﻴﺞ ﺍﻟﻌﺭﺒﻲ. ﻭﺴﻴﺘﻡ ﺍﺴﺘﻌﺭﺍﺽ ﺨﻭﺍﺹ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﻤﻨﺎﻁﻕ ﺍﻟﺭﻴﺎﺱ ،ﻭﺍﻟﻘﺭﻴﺔ، ﻭﺍﻟﻌﺯﻴﺯﻴﺔ ،ﻭﺭﺃﺱ ﺍﻟﻐﺎﺭ ﻓﻲ ﺍﻟﻤﻨﻁﻘﺔ ﺍﻟﺸﺭﻗﻴﺔ.
ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺍﻟﻤﻤﻠﻜﺔ ﺍﻟﻌﺭﺒﻴﺔ ﺍﻟﺴﻌﻭﺩﻴﺔ ....
45
ﺠﺩﻭل ) (2ﺍﻟﺘﺭﻜﻴﺏ ﺍﻟﻜﻴﻤﻴﺎﺌﻲ ﻟﻤﻴﺎﻩ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺍﻟﻤﻨﻁﻘﺔ ﺍﻟﺸﺭﻗﻴﺔ ﻤﻘﺎﺭﻨﺔ ﺒﻤﻴﺎﻩ ﺍﻟﺨﻠﻴﺞ ﺍﻟﻌﺭﺒﻲ ﺍﻷﻴﻭﻨﺎﺕ ﺍﻟﺼﻭﺩﻴﻭﻡ )(Na+
ﺍﻟﻤﻐﻨﺴﻴﻭﻡ )(Mg++ ﺍﻟﺒﻭﺘﺎﺴﻴﻭﻡ )(K+
ﺍﻟﻜﺎﻟﺴﻴﻭﻡ )(Ca++ ﺍﻟﺤﺩﻴﺩ )(Fe++
ﺍﻟﺴﺘﺭﻭﻨﺘﻴﻭﻡ )(Sr++
ﺍﻟﻜﻠﻭﺭ )(Cl-
ﺍﻟﺒﺭﻭﻤﻴﻥ )(Br-
ﺍﻟﻜﺒﺭﻴﺘﺎﺕ (So4)--
ﺍﻟﺒﻴﻜﺭﺒﻭﻨﺎﺕ (HCO3)-
ﺍﻟﺭﻗﻡ ﺍﻟﻬﻴﺩﺭﻭﺠﻴﻨﻲ )(pH
ﺍﻟﻤﻭﺼﻠﻴﺔ ) (Conductivityﻤﻴﻜﺭﻭﺴﻴﻤﻨﺯ
][21
ﻤﻴﺎﻩ ﺍﻟﺴﺒﺨﺔ ]ﺠﺯﺀ ﻤﻥ ﺍﻷﻟﻑ[ )ﻤﻐﻡ/ﻤﻠل(
ﻤﻴﺎﻩ ﺍﻟﺨﻠﻴﺞ ﺍﻟﻌﺭﺒﻲ ]ﺠﺯﺀ ﻤﻥ ﺍﻷﻟﻑ[ )ﻤﻐﻡ/ﻤﻠل(
78.8
20.7
10.32
2.30
3.06
0.73
1.45
0.76
ﻤﻘﺩﺍﺭ ﻀﺌﻴل
ﻤﻘﺩﺍﺭ ﻀﺌﻴل
0.029
0.013
157.2
36.9
0.49
0.121
5.45
5.12
0.078
0.128
6.9
8.3
208000
46200
4ـ 1ـ 1ﺴﺒﺨﺔ ﺍﻟﺭﻴﺎﺱ: ﺘﻌﺩ ﺴﺒﺨﺔ ﺍﻟﺭﻴﺎﺱ ﻤﻥ ﺃﻜﺒﺭ ﺍﻟﺴﺒﺨﺎﺕ ﻓﻲ ﺍﻟﻤﻨﻁﻘﺔ ﺍﻟﺸﺭﻗﻴﺔ ﺤﻴﺙ ﺘﺒﺩﺃ ﻋﻠﻰ ﺒﻌﺩ 30ﻜﻠﻡ ﺸﻤﺎل ﻏﺭﺒﻲ ﻤﺩﻴﻨﺔ ﺍﻟﻅﻬﺭﺍﻥ ،ﻭﺘﻤﺘﺩ ﺇﻟﻰ ﻤﺎ ﻴﻘﺎﺭﺏ 70ﻜﻠﻡ ﺒﺎﺘﺠﺎﻩ ﺍﻟﺸﻤﺎل ﺍﻟﻐﺭﺒﻲ ﺇﻟﻰ ﻤﺩﻴﻨﺔ ﺍﻟﺠﺒﻴل .ﻭﻴﺨﺘﻠﻑ ﻋﺭﺽ ﻫﺫﻩ ﺍﻟﺴﺒﺨﺔ ﻤﻥ ﺒﻀﻌﺔ ﻜﻴﻠﻭﻤﺘﺭﺍﺕ ﺇﻟﻰ 12ﻜﻠﻡ ] .[19ﻭﻴﻜﻭﻥ ﺴﻁﺤﻬﺎ ﻤﺴﺘﻭﻴﹰﺎ ﻓﻲ ﺍﻟﻐﺎﻟﺏ ،ﻜﻤﺎ ﺘﺘﻭﺍﺠﺩ ﺒﻌﺽ ﺍﻟﺘﻼل ﺍﻟﺼﻐﻴﺭﺓ ﺍﻟﺘﻲ ﺘﺭﺘﻔﻊ ﺤﻭﺍﻟﻲ ﺨﻤﺴﺔ ﺇﻟﻰ ﻋﺸﺭﺓ ﺃﻤﺘﺎﺭ ﻓﻭﻕ ﺴﻁﺢ
ﻋﺒﺩﺍﷲ ﺒﻥ ﺇﺒﺭﺍﻫﻴﻡ ﺍﻟﻤﻬﻴﺩﺏ
46
ﺍﻟﺴﺒﺨﺔ ﻭﺍﻟﺘﻲ ﺘﻐﻁﻰ ﻋﺎﺩﺓ ﺒﺎﻟﻜﺜﺒﺎﻥ ﺍﻟﺭﻤﻠﻴﺔ ] ،[19ﻜﻤﺎ ﺃﻥ ﻤﻨﺴﻭﺏ ﺍﻟﻤﻴﺎﻩ ﺍﻟﺠﻭﻓﻴﺔ ﻓﻲ ﺍﻟﻐﺎﻟﺏ ﻴﺘﺭﺍﻭﺡ ﺒﻴﻥ 30ﺴﻡ ﻭ 1.15ﻤﺘﺭ ﺤﻴﺙ ﻴﻌﺘﻤﺩ ﻋﻠﻰ ﻤﻌﺩل ﻫﻁﻭل ﺍﻷﻤﻁﺎﺭ ﻭﻤﻌﺩل ﺍﻟﺘﺒﺨﺭ].[2 ﻭﻴﻭﻀﺢ ﺸﻜل ) (7ﻤﻘﻁﻌﹰﺎ ﺠﺎﻨﺒﻴﹰﺎ ﻟﺴﺒﺨﺔ ﺍﻟﺭﻴﺎﺱ ﺤﻴﺙ ﺘﺘﻜﻭﻥ ﺍﻟﻁﺒﻘﺔ ﺍﻟﻌﻠﻴﺎ ﻤﻥ ﺍﻟﺭﻤل ﻭﺍﻟﻁﻤﻲ ،ﻭﺍﻟﻤﻠﺢ ﻭﺍﻻﻨﻬﺩﺭﺍﻴﺕ ﺍﻟﻐﻴﺭ ﻤﺘﺒﻠﻭﺭﻴﻥ ،ﻭﺘﻠﻴﻬﺎ ﻁﺒﻘﺔ ﻤﻥ ﺍﻟﻤﻠﺢ ﺍﻟﻤﺘﻤﺎﺴﻙ ﻭﺍﻟﻤﺘﺒﻠﻭﺭ ﻤﻊ ﺍﻟﺭﻤل ﻭﺍﻟﻁﻤﻲ ،ﺜﻡ ﺘﺘﺒﻌﻬﺎ ﻁﺒﻘﺔ ﻤﻥ ﺍﻟﻭﺤل ﺍﻟﻐﻴﺭ ﻋﻀﻭﻱ ﺍﻟﻌﺎﻟﻲ ﺍﻟﻠﺩﻭﻨﺔ ،ﺜﻡ ﻁﺒﻘﺔ ﻤﻥ ﺍﻟﺭﻤل ﺍﻟﻀﻌﻴﻑ ﺍﻟﺘﺩﺭﺝ ﺫﻱ ﺍﻟﻠﻭﻥ ﺍﻟﺭﻤﺎﺩﻱ ﺍﻟﻐﺎﻤﻕ، ﺜﻡ ﻁﺒﻘﺔ ﻤﻥ ﺍﻟﺭﻤﺎل ﺒﻨﻴﺔ ﺍﻟﻠﻭﻥ ﻤﻊ ﻭﺤل ﻋﺎﻟﻰ ﺍﻟﻠﺩﻭﻨﺔ ،ﺜﻡ ﻁﺒﻘﺔ ﻤﻥ ﺍﻟﺠﺒﺱ ﺍﻟﻤﺘﺒﻠﻭﺭ ﻤﻊ ﻭﺤل ﺃﺼﻔﺭ].[2
47
ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺍﻟﻤﻤﻠﻜﺔ ﺍﻟﻌﺭﺒﻴﺔ ﺍﻟﺴﻌﻭﺩﻴﺔ ....
ﻭﻴﺒﻴﻥ ﺠﺩﻭل ) (3ﺍﻟﺨﻭﺍﺹ ﺍﻟﺠﻴﻭﺘﻜﻨﻴﻜﻴﺔ ﻷﺭﺒﻊ ﻋﺸﺭ ﻋﻴﻨﺔ ﻤﻥ ﺴﺒﺨﺔ ﺍﻟﺭﻴﺎﺱ، ﺤﻴﺙ ﻴﺘﻀﺢ ﺃﻥ ﺍﻟﺘﺭﺒﺔ ﻓﻲ ﺍﺜﻨﻲ ﻋﺸﺭ ﻤﻭﻗﻌﹰﺎ ﻟﻴﺴﺕ ﻟﺩﻨﺔ .ﻭﻜﺎﻨﺕ ﻗﻴﻤﺘﺎ ﺤﺩ ﺍﻟﺴﻴﻭﻟﺔ ﻟﻌﻴﻨﺘﻴﻥ ﻫﻲ 24.8ﻭ ،34.5ﻭﻗﻴﻤﺘﺎ ﺤﺩ ﺍﻟﻠﺩﻭﻨﺔ ﻟﻬﻤﺎ ﻫﻲ 17.6ﻭ . 21.2ﻭﺘﻡ ﻻ ﻤﻥ ﺍﻟﻤﺎﺀ ﺍﻟﻤﻘﻁﺭ ،ﻷﻥ ﺍﺴﺘﺨﺩﺍﻡ ﺍﺴﺘﺨﺩﺍﻡ ﻤﻴﺎﻩ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺍﻟﺘﺠﺎﺭﺏ ﺍﻟﻤﻌﻤﻠﻴﺔ ﺒﺩ ﹰ ﺍﻟﻤﺎﺀ ﺍﻟﻤﻘﻁﺭ ﻴﻌﻤل ﻋﻠﻰ ﺘﻔﻜﻴﻙ ﺤﺒﻴﺒﺎﺕ ﺍﻟﺘﺭﺒﺔ ،ﻭﺒﺎﻟﺘﺎﻟﻲ ﻓﺈﻨﻪ ‘ﻴﻨﺼﺢ ﺒﺎﺴﺘﺨﺩﺍﻡ ﻤﻴﺎﻩ ﺍﻟﺴﺒﺨﺔ ﻋﻨﺩ ﺇﻴﺠﺎﺩ ﺨﻭﺍﺼﻬﺎ ﻓﻲ ﺍﻟﻤﻌﻤل ] .[2ﻭﻴﺒﻴﻥ ﺍﻟﺠﺩﻭل ﻜﺫﻟﻙ ﺃﻥ ﻗﻴﻡ ﻨﺴﺒﺔ ﺘﺤﻤل ﻜﺎﻟﻴﻔﻭﺭﻨﻴﺎ ﺍﻟﻌﻠﻴﺎ ﺘﺘﺭﺍﻭﺡ ﺒﻴﻥ 32ﻭ 108ﻭﻤﺘﻭﺴﻁ ﺍﻟﻘﻴﻡ ﻫﻭ 76ﻤﻤﺎ ﻴﺩل ﻋﻠﻰ ﺃﻥ ﻗﻭﺓ ﺘﺤﻤل ﺍﻟﺘﺭﺒﺔ ﻋﺎﻟﻴﺔ .ﻜﻤﺎ ﺃﻥ ﺘﺼﻨﻴﻑ ﺁﺸﺘﻭ ﻟﻠﺘﺭﺒﺔ ﻟﻤﻌﻅﻡ ﺍﻟﻌﻴﻨﺎﺕ ﻴﺒﻴﻥ ﺃﻥ ﺍﻟﺘﺭﺒﺔ ﺘﻌﺘﺒﺭ ﻤﺎﺩﺓ ﺠﻴﺩﺓ ﻟﻼﺴﺘﺨﺩﺍﻡ ﻜﻘﺎﻋﺩﺓ ﺘﺄﺴﻴﺱ ﺘﺭﺍﺒﻴﺔ ﻟﻠﻁﺭﻴﻕ. 4ـ 1ـ 2ﺴﺒﺨﺔ ﺍﻟﻘﺭﻴﺔ: ﺘﻘﻊ ﺴﺒﺨﺔ ﺍﻟﻘﺭﻴﺔ ﺸﺭﻕ ﻤﺩﻴﻨﺔ ﺍﺒﻘﻴﻕ ﺒﺠﻭﺍﺭ ﻤﺤﻁﺔ ﻜﻬﺭﺒﺎﺀ ﺍﻟﻘﺭﻴﺔ ﺤﻴﺙ ﻴﻭﺠﺩ ﻤﻨﺘﺠﻊ ﺸﺎﻁﺊ ﺸﺭﻜﺔ ﺃﺭﺍﻤﻜﻭ ﺍﻟﺴﻌﻭﺩﻴﺔ .ﻭﺘﺘﻤﻴﺯ ﻫﺫﻩ ﺍﻟﺴﺒﺨﺔ ﺒﻭﺠﻭﺩ ﻤﺎ ﻴﺴﻤﻰ ﺒﺒﺭﻙ ﻜﺒﻴﺭﺓ ﻤﻥ ﺍﻷﻤﻼﺡ ﺘﻐﻁﻲ ﻜﺎﻤل ﺴﻁﺢ ﺍﻟﺴﺒﺨﺔ ،ﻭﻴﻌﻭﺩ ﺴﺒﺏ ﺘﻭﺍﺠﺩ ﻫﺫﻩ ﺍﻷﻤﻼﺡ ﺒﻬﺫﻩ ﺍﻟﻜﻤﻴﺎﺕ ﺇﻟﻰ ﺘﺤﻠل ﺍﻷﻤﻼﺡ ﺍﻟﻤﺘﻭﺍﺠﺩﺓ ﻓﻲ ﺍﻟﻘﺸﺭﺓ ﺍﻟﺴﻁﺤﻴﺔ ﻟﻠﺴﺒﺨﺔ ﺒﻭﺍﺴﻁﺔ ﻤﻴﺎﻩ ﺍﻷﻤﻁﺎﺭ ﺍﻟﺘﻲ ﺘﺴﺒﺒﺕ ﺃﻴﻀﺎ ﻓﻲ ﺍﺭﺘﻔﺎﻉ ﻤﻨﺴﻭﺏ ﺍﻟﻤﻴﺎﻩ ﺍﻟﺠﻭﻓﻴﺔ ﻭﺒﺎﻟﺘﺎﻟﻲ ﺯﻴﺎﺩﺓ ﻤﻌﺩل ﺍﻟﺘﺒﺨﺭ ﻤﻥ ﺍﻟﺴﻁﺢ ﻤﻤﺎ ﻨﺘﺞ ﻋﻨﻪ ﻅﻬﻭﺭ ﻜﻤﻴﺎﺕ ﻜﺒﻴﺭﺓ ﻤﻥ ﺍﻷﻤﻼﺡ ﻋﻠﻰ ﺍﻟﺴﻁﺢ .ﻟﻘﺩ ﺒﻠﻎ ﺇﻨﺘﺎﺝ ﻫﺫﻩ ﺍﻟﺴﺒﺨﺔ ﻋﺸﺭﺍﺕ ﺍﻷﻁﻨﺎﻥ ﻤﻥ ﺍﻷﻤﻼﺡ ﻴﻭﻤﻴﹰﺎ ﺨﻼل ﺸﻬﺭ ﺃﺒﺭﻴل ﻤﻥ ﻋﺎﻡ 1995ﻡ ] .[2ﻭﺘﺘﻜﻭﻥ ﺍﻟﺭﺴﻭﺒﻴﺎﺕ ﻓﻲ ﻫﺫﻩ ﺍﻟﻤﻨﻁﻘﺔ ﻤﻥ ﺍﻟﻘﺸﺭﺓ ﺍﻟﺴﻁﺤﻴﺔ ﺍﻟﻤﺎﻟﺤﺔ ﻭﻨﻭﻋﻴﻥ ﻤﻥ ﺍﻟﻁﺒﻘﺎﺕ ﺍﻟﺭﻤﻠﻴﺔ ﻭﺍﻟﻠﺘﻴﻥ ﺘﺘﻜﻭﻨﺎﻥ ﻤﻥ ﺭﻤﺎل ﻨﺎﻋﻤﺔ ﻤﺤﺘﻭﻴﺔ ﻋﻠﻰ ﺒﻌﺽ ﺍﻟﻁﻤﻲ ﻭﺍﻟﺭﻤﺎل ﺍﻟﺨﺸﻨﺔ ،ﻭﻜﻠﺘﺎ ﺍﻟﻁﺒﻘﺘﻴﻥ ﺍﻟﺭﻤﻠﻴﺘﻴﻥ ﻤﻔﻜﻜﺘﺎﻥ .ﻭﺘﺘﻤﻴﺯ ﻫﺫﻩ ﺍﻟﺴﺒﺨﺔ ﺒﺎﺤﺘﻭﺍﺌﻬﺎ ﻋﻠﻰ ﺍﻟﺠﻴﺭ ﺇﻀﺎﻓﺔ ﺇﻟﻰ ﻜﺒﺭﻴﺘﺎﺕ ﺍﻟﻜﺎﻟﺴﻴﻭﻡ ﺍﻟﻤﺎﺌﻴﺔ )ﺍﻟﺠﺒﺱ( ﻭﺍﻟﻬﺎﻻﻴﺕ.
ﻋﺒﺩﺍﷲ ﺒﻥ ﺇﺒﺭﺍﻫﻴﻡ ﺍﻟﻤﻬﻴﺩﺏ
48
ﺠﺩﻭل ) : (3ﺨﻭﺍﺹ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﻤﻨﻁﻘﺔ ﺍﻟﺭﻴﺎﺱ ﻭﺘﺼﻨﻴﻔﻬﺎ ﺒﺎﺴﺘﺨﺩﺍﻡ ﻤﻴﺎﻩ ﺍﻟﺴﺒﺨﺔ
4
1.8
5
17.3
6
14.6
7
43
8
34
-
ﺍﻟﻌﻴﻨﺔ 3
21
)(%
max
Unified
2
34
-
ﻏﻴﺭ ﻟﺩﻥ
wopt
CBR
at CBR
ﺍﻟﻨﻅﺎﻡ ﺍﻟﻤﻭﺤﺩ
1
65
-
3
) (g/cm
ﻜﺎﻟﻴﻔﻭﺭﻨﻴﺎ
ﺘﺤﻤل
AASHTO
ﺤﺩ ﺍﻟﺴﻴﻭﻟﺔ
ﻤﻌﻴﺎﺭ ﺤﺩ ﺍﻟﻠﺩﻭﻨﺔ ﺍﻟﻠﺩﻭﻨﺔ
ﺃﻜﺒﺭ ﻜﺜﺎﻓﺔ ﺠﺎﻓﺔ γd max
ﺍﻟﺭﻁﻭﺒﺔ ﺍﻟﻤﺜﻠﻰ ﺍﻟﻤﺤﺘﻭﺍﻩ
ﻨﺴﺒﺔ
ﺍﻟﺭﻁﻭﺒﺔ ﺍﻟﻤﺜﻠﻰ ﺍﻟﻤﺤﺘﻭﺍﻩ wopt
ﺍﻟﺘﺼﻨﻴﻑ
ﻨﻅﺎﻡ ﺁﺸﺘﻭ
ﺍﻟﻤﺎﺭ ﻤﻥ ﻤﻨﺨل # 200
ﺘﺠﺎﺭﺏ ﺍﻟﺩﻤﻙ
][2
max
)(%
1.91
10.8
66
6
ML
A-4
2.03
7.7
84
6.4
SM
A-2-4
1.94
11.2
89
9.4
SM
A-2-4
1.85
10.5
32
8.6
SP
A-3
2.02
10.8
90
8.7
SM
A-2-4
2.02
8.3
73
6.2
SM
A-2-4
1.89
11.5
78
7.2
SM
A-4
ﻏﻴﺭ ﻟﺩﻥ
2.00
9.1
80
6.5
SM
A-2-4
9
76
34.5
21.1
13.4
1.73
16.5
56
14
CL
A-6
10
78
-
-
ﻏﻴﺭ ﻟﺩﻥ
1.75
17.4
65
11.3
ML
A-4
11
7.5
-
-
ﻏﻴﺭ ﻟﺩﻥ
1.84
11.9
93
9.8
12
9
-
-
ﻏﻴﺭ ﻟﺩﻥ
2.03
8
88
5.8
13
19
-
-
ﻏﻴﺭ ﻟﺩﻥ
1.97
11.8
108
9.8
14
81
24.8
17.6
7.2
1.76
16.2
70
9
-
-
ﻏﻴﺭ ﻟﺩﻥ ﻏﻴﺭ ﻟﺩﻥ ﻏﻴﺭ ﻟﺩﻥ ﻏﻴﺭ ﻟﺩﻥ ﻏﻴﺭ ﻟﺩﻥ ﻏﻴﺭ ﻟﺩﻥ
SPSM SPSM SM ML -CL
A-3
A-3 A-2-4 A-4
ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺍﻟﻤﻤﻠﻜﺔ ﺍﻟﻌﺭﺒﻴﺔ ﺍﻟﺴﻌﻭﺩﻴﺔ ....
49
ﻭﻴﺘﺭﺍﻭﺡ ﻤﻨﺴﻭﺏ ﺍﻟﻤﻴﺎﻩ ﺍﻟﺠﻭﻓﻴﺔ ﺒﻴﻥ 31ﺴﻡ ﻭ 48ﺴﻡ ﻤﻥ ﺴﻁﺢ ﺍﻷﺭﺽ، ﻜﻤﺎ ﺘﺒﻠﻎ ﺍﻟﻜﺜﺎﻓﺔ ﺍﻟﺠﺎﻓﺔ ﻓﻲ ﺍﻟﻤﻭﻗﻊ ﺤﻭﺍﻟﻲ 1.15ﺠﻡ/ﺴﻡ 3ﺇﻟﻰ 1.57ﺠﻡ/ﺴﻡ، 3 ﺒﻴﻨﻤﺎ ﺍﻟﻜﺜﺎﻓﺔ ﺍﻟﺭﻁﺒﺔ ﺤﻭﺍﻟﻲ 1.31ﺠﻡ/ﺴﻡ 3ﺇﻟﻰ 1.85ﺠﻡ/ﺴﻡ ، 3ﻭﺍﻟﻤﺤﺘﻭﻯ ﺍﻟﻤﺎﺌﻲ ﺤﻭﺍﻟﻲ % 13.8ﺇﻟﻰ .% 16.1ﻭﻴﺒﻴﻥ ﺠﺩﻭل ) (4ﺍﻟﺨﻭﺍﺹ ﺍﻟﺠﻴﻭﺘﻜﻨﻴﻜﻴﺔ ﻟﺜﻼﺙ ﻋﻴﻨﺎﺕ ﻤﻥ ﺴﺒﺨﺔ ﺍﻟﻘﺭﻴﺔ ،ﺤﻴﺙ ﻴﺘﻀﺢ ﺃﻥ ﺍﻟﺘﺭﺒﺔ ﻟﻴﺴﺕ ﻟﺩﻨﺔ .ﻭﻴﺘﺒﻴﻥ ﻤﻥ ﻫﺫﺍ ﺍﻟﺠﺩﻭل ﺃﻥ ﻗﻴﻡ ﻨﺴﺒﺔ ﺘﺤﻤل ﻜﺎﻟﻴﻔﻭﺭﻨﻴﺎ ﺍﻟﻌﻠﻴﺎ ﻟﻌﻴﻨﺘﻴﻥ ﺃﻜﺒﺭ ﻤﻥ 100ﺃﻤﺎ ﺍﻟﻌﻴﻨﺔ ﺍﻟﺜﺎﻟﺜﺔ ﻓﺈﻥ ﻗﻴﻤﺘﻬﺎ ﻫﻲ 52ﻤﻤﺎ ﻴﺩل ﻋﻠﻰ ﺃﻥ ﻗﻭﺓ ﺘﺤﻤل ﺍﻟﺘﺭﺒﺔ ﻋﺎﻟﻴﺔ ﺒﺸﻜل ﻋﺎﻡ. ﺠﺩﻭل ) : (4ﺨﻭﺍﺹ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﻤﻨﻁﻘﺔ ﺍﻟﻘﺭﻴﺔ ﻭﺘﺼﻨﻴﻔﻬﺎ ﺒﺎﺴﺘﺨﺩﺍﻡ ﻤﻴﺎﻩ ﺍﻟﺴﺒﺨﺔ ﺍﻟﻤﺎﺭ ﻤﻥ ﻤﻨﺨل 200 #
ﺤﺩ ﺍﻟﺴﻴﻭﻟﺔ
ﻤﻌﻴﺎﺭ ﺍﻟﻠﺩﻭﻨﺔ
3
wopt
) (g/cm
CBR
)(%
ﺍﻟﻤﺤﺘﻭﺍﻩ wopt at CBR
Unified
3
39
-
-
γd max
ﺍﻟﻤﺤﺘﻭﺍﻩ
ﻜﺎﻟﻴﻔﻭﺭﻨﻴﺎ
ﺍﻟﻤﺜﻠﻰ ﺍﻟﻨﻅﺎﻡ ﺍﻟﻤﻭﺤﺩ
2
55
-
-
ﺠﺎﻓﺔ
ﺍﻟﻤﺜﻠﻰ
ﺘﺤﻤل
ﺍﻟﺭﻁﻭﺒﺔ ﻨﻅﺎﻡ ﺁﺸﺘﻭ
1
28
-
ﻜﺜﺎﻓﺔ
ﺍﻟﺭﻁﻭﺒﺔ
ﻨﺴﺒﺔ
ﺍﻟﺘﺼﻨﻴﻑ
AASHTO
ﺤﺩ ﺍﻟﻠﺩﻭﻨﺔ
ﺃﻜﺒﺭ
-
ﺍﻟﻌﻴﻨﺔ
ﺘﺠﺎﺭﺏ ﺍﻟﺩﻤﻙ
][2
max
max )(%
ﻏﻴﺭ ﻟﺩﻥ ﻏﻴﺭ ﻟﺩﻥ ﻏﻴﺭ ﻟﺩﻥ
1.91
12.6
124
9.6
SM
A-2-4
1.85
15
52
10.8
ML
A-4
1.83
15.3
108
10.9
SM
A-4
ﻋﺒﺩﺍﷲ ﺒﻥ ﺇﺒﺭﺍﻫﻴﻡ ﺍﻟﻤﻬﻴﺩﺏ
50
4ـ 1ـ 3ﺴﺒﺨﺔ ﺍﻟﻌﺯﻴﺯﻴﺔ: ﻤﻨﻁﻘﺔ ﺍﻟﻌﺯﻴﺯﻴﺔ ﻫﻲ ﺃﺤﺩ ﺸﻭﺍﻁﺊ ﻤﺩﻴﻨﺔ ﺍﻟﺨﺒﺭ ،ﻭﻗﺩ ﺘﻡ ﺃﺨﺫ ﻋﻴﻨﺔ ﺍﻟﺴﺒﺨﺔ ﻤﻥ ﻤﻨﻁﻘﺔ ﺘﺒﻌﺩ ﺤﻭﺍﻟﻲ 2ﻜﻴﻠﻭﻤﺘﺭ ﻤﻥ ﺤﺩﻭﺩ ﻤﻁﺎﺭ ﺍﻟﻅﻬﺭﺍﻥ ﺍﻟﺩﻭﻟﻲ ﺍﻟﻘﺩﻴﻡ .ﻭﻴﺒﻠﻎ ﻤﺘﻭﺴﻁ ﺍﻟﻜﺜﺎﻓﺔ ﺍﻟﺠﺎﻓﺔ ﻓﻲ ﺍﻟﻤﻭﻗﻊ ﺤﻭﺍﻟﻲ 1.76ﺠﻡ/ﺴﻡ 3ﺒﻴﻨﻤﺎ ﺍﻟﻜﺜﺎﻓﺔ ﺍﻟﺭﻁﺒﺔ ﺤﻭﺍﻟﻲ 1.91ﺠﻡ/ﺴﻡ 3ﻭﺍﻟﻤﺤﺘﻭﻯ ﺍﻟﻤﺎﺌﻲ ﺤﻭﺍﻟﻲ .%8.4ﻭﻜﺎﻥ ﻤﻨﺴﻭﺏ ﺍﻟﻤﻴﺎﻩ ﺍﻟﺠﻭﻓﻴﺔ ﻋﻠﻰ ﺒﻌﺩ 72ﺴﻡ ﻤﻥ ﺴﻁﺢ ﺍﻷﺭﺽ ] .[2ﻭﺃﻭﻀﺤﺕ ﻨﺘﺎﺌﺞ ﺍﻟﺘﺠﺎﺭﺏ ﺍﻟﻤﻌﻤﻠﻴﺔ ﺒﺎﺴﺘﺨﺩﺍﻡ ﻤﻴـﺎﻩ ﺍﻟﺴﺒﺨـﺔ ﺃﻥ ﺤﻭﺍﻟﻲ %4.40ﻤﺭﺕ ﻤﻥ ﻤﻨﺨل ﺭﻗﻡ ،200ﻭﺃﻥ ﺍﻟﺘﺭﺒﺔ ﻟﻴﺴﺕ ﻟﺩﻨﺔ ،ﻜﻤﺎ ﺃﻥ ﺘﺼﻨﻴﻑ ﺍﻟﺘﺭﺒﺔ ﻫﻭ SPﻁﺒﻘ ﹰﺎ ﻟﻨﻅﺎﻡ ﺍﻟﺘﺼﻨﻴﻑ ﺍﻟﻤﻭﺤﺩ ،ﻭ A − 3ﻁﺒﻘ ﹰﺎ ﻟﻨﻅﺎﻡ ﺍﻵﺸﺘﻭ ] .[2ﻜﻤﺎ ﺒﻠﻐﺕ ﺃﻜﺒﺭ ﻜﺜﺎﻓﺔ ﺠﺎﻓﺔ 2.05ﺠﻡ/ﺴﻡ 3ﻋﻨﺩ %6.5ﻨﺴﺒﺔ ﺍﻟﺭﻁﻭﺒﺔ ﺍﻟﻤﺜﻠﻰ ﺍﻟﻤﺤﺘﻭﺍﻩ ،ﻭﻜﺎﻨﺕ ﺃﻜﺒﺭ ﻗﻴﻤﺔ ][2 ﺍﻟﺘﺤﻤل ﻟﻨﺴﺒﺔ ﻜﺎﻟﻴﻔﻭﺭﻨﻴﺎ ﻫﻲ 46ﻋﻨﺩ %6.5ﻨﺴﺒﺔ ﺍﻟﺭﻁﻭﺒﺔ ﺍﻟﻤﺜﻠﻰ ﺍﻟﻤﺤﺘﻭﺍﻩ ﺤﻴﺙ ﺘﻌﺘﺒﺭ ﻗﻭﺓ ﺘﺤﻤل ﺍﻟﺘﺭﺒﺔ ﻤﺘﻭﺴﻁﺔ. ﻭﻴﺒﻴﻥ ﺸﻜل ) (8ﻤﻘﻁ ًﻌﺎ ﺠﺎﻨﺒ ًﻴﺎ ﻟﻠﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﻤﻨﻁﻘﺔ ﺍﻟﻌﺯﻴﺯﻴﺔ ﺤﻴﺙ ﻴﺘﻀﺢ ﻤﻨﻪ ﺃﻥ ﻗﻴﻡ ﻋﺩﺩ ﺍﻟﻀﺭﺒﺎﺕ ﻻﺨﺘﺒﺎﺭ ﺍﻻﺨﺘﺭﺍﻕ ﺍﻟﻘﻴﺎﺴﻲ ) (SPTﺘﺘﺭﻭﺍﺡ ﺒﻴﻥ 6ﻭ14 ﺤﻴﺙ ﺘﻌﺘﺒﺭ ﻫﺫﻩ ﺍﻟﻘﻴﻡ ﻗﻠﻴﻠﺔ ﻨﺴﺒﻴﹰﺎ ﻤﻤﺎ ﻴﺩل ﻋﻠﻰ ﺃﻥ ﺍﻟﺘﺭﺒﺔ ﻤﻔﻜﻜﺔ ﻭﺃﻥ ﻗﻭﺓ ﺘﺤﻤﻠﻬﺎ ﻀﻌﻴﻔﺔ . 4ـ 1ـ 4ﺴﺒﺨﺔ ﺭﺃﺱ ﺍﻟﻐﺎﺭ: ﺘﻘﻊ ﺴﺒﺨﺔ ﺭﺃﺱ ﺍﻟﻐﺎﺭ ﻋﻠﻰ ﺒﻌﺩ 15ﻜﻴﻠﻭ ﻤﺘﺭ ﺠﻨﻭﺏ ﻤﺩﻴﻨﺔ ﺍﻟﺠﺒﻴل .ﻭﺘﺘﻜﻭﻥ ﺍﻟﺘﺭﺒﺔ ﻓﻲ ﺭﺃﺱ ﺍﻟﻐﺎﺭ ] [22ـ ﻜﻤﺎ ﻫﻭ ﻤﻭﻀﺢ ﻓﻲ ﺸﻜل ) (9ﻤﻥ ﻁﺒﻘﺔ ﻋﻠﻴﺎ ﺴﻤﻜﻬﺎ ﺤﻭﺍﻟﻲ 3.5ﻤﺘﺭﹰﺍ ﻤﻜﻭﻨﺔ ﻤﻥ ﺭﻤل ﺨﻔﻴﻑ ﺇﻟﻰ ﻤﺘﻭﺴﻁ ﺍﻟﻜﺜﺎﻓﺔ ﻟﻭﻨﻪ ﺒﻨﻲ ﻤﻊ ﻤﻠﺢ ﻤﺘﺒﻠﻭﺭ ،ﻭﺃﺴﻔل ﻫﺫﻩ ﺍﻟﻁﺒﻘﺔ ﻴﻭﺠﺩ ﻁﺒﻘﺔ ﻤﻜﻭﻨﺔ ﻤﻥ ﺍﻟﻤﻠﺢ ﺍﻟﺼﺨﺭﻱ )ﺍﻟﻬﺎﻻﻴﺕ( ﺴﻤﻜﻬﺎ ﺤﻭﺍﻟﻲ 1.5ﻤﺘﺭﹰﺍ ﺫﺍﺕ ﻗﻴﻡ ﻋﺎﻟﻴﺔ ﻟﻌﺩﺩ ﺍﻟﻀﺭﺒﺎﺕ ﻻﺨﺘﺒﺎﺭ ﺍﻻﺨﺘﺭﺍﻕ ﺍﻟﻘﻴﺎﺴﻲ .ﻭﺍﻟﻁﺒﻘـﺔ ﺍﻟﺴﻔﻠﻰ ﻤﻜﻭﻨﺔ ﻤﻥ ﺭﻤل ﺠﻴﺭﻱ ﻟﻭﻨﻪ ﺭﻤﺎﺩﻱ ﻓﺎﺘﺢ ﺴﻤﻜﻬﺎ
51
ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺍﻟﻤﻤﻠﻜﺔ ﺍﻟﻌﺭﺒﻴﺔ ﺍﻟﺴﻌﻭﺩﻴﺔ ....
ﺤﻭﺍﻟﻲ 10ﻤﺘﺭﹰﺍ .ﻭﻴﻭﺠﺩ ﻤﻨﺴﻭﺏ ﺍﻟﻤﻴﺎﻩ ﺍﻟﺠﻭﻓﻴﺔ ﻋﻠﻰ ﺒﻌﺩ 80ﺴﻡ ﻤﻥ ﺴﻁﺢ ﺍﻷﺭﺽ ].[22
ﻋﺒﺩﺍﷲ ﺒﻥ ﺇﺒﺭﺍﻫﻴﻡ ﺍﻟﻤﻬﻴﺩﺏ
52
ﻭﻴﺒﻴﻥ ﺠﺩﻭل ) (5ﺍﻟﺨﺼﺎﺌﺹ ﺍﻟﺠﻴﻭﺘﻜﻨﻴﻜﻴﺔ ﻟﻠﺘﺭﺒﺔ ﻓﻲ ﺍﻟﻁﺒﻘﺔ ﺍﻟﻌﻠﻴﺎ ﻓﻲ ﺭﺃﺱ ﺍﻟﻐﺎﺭ ﺤﻴﺙ ﺘﺘﻀﺢ ﺍﻟﺨﻭﺍﺹ ﺍﻟﻀﻌﻴﻔﺔ ﻟﻠﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻤﻥ ﻗﻴﻡ ﻨﺴﺒﺔ ﺘﺤﻤل ﻜﺎﻟﻴﻔﻭﺭﻨﻴﺎ ﻭﻤﻌﺎﻤل ﻁﺒﻘﺔ ﺍﻟﺘﺄﺴﻴﺱ .ﻭﻗﺩ ﺃﻭﻀﺤﺕ ﻨﺘﺎﺌﺞ ﺍﻟﺘﺤﻠﻴل ﺍﻟﻜﻴﻤﻴﺎﺌﻲ ﻟﻤﻴﺎﻩ ﺍﻟﺴﺒﺨﺔ ﻓـﻲ ﻫﺫﻩ ﺍﻟﻁﺒﻘﺔ ﺘﺭﻜﻴﺯ ﺍﻷﻤﻼﺡ ﺨﺎﺼﺔ ﺍﻟﺼﻭﺩﻴﻭﻡ ﻭﺍﻟﻜﻠﻭﺭﻴﺩ ﻓﻲ ﻤﻴﺎﻩ ﺍﻟﺴﺒﺨﺔ ﻤﻘﺎﺭﻨـﺔ ﺒﻤﻴﺎﻩ ﺍﻟﺒﺤﺭ ﺍﻟﻌﺎﺩﻴﺔ ].[22
53
ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺍﻟﻤﻤﻠﻜﺔ ﺍﻟﻌﺭﺒﻴﺔ ﺍﻟﺴﻌﻭﺩﻴﺔ ....
ﺠﺩﻭل ﺭﻗﻡ ) : (5ﺍﻟﺨﻭﺍﺹ ﺍﻟﺠﻴﻭﺘﻜﻨﻴﻜﻴﺔ ﻟﻠﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺭﺃﺱ ﺍﻟﻐﺎﺭ
ﺍﻟﺨﺎﺼﻴﺔ ﺍﻟﻤﻭﺍﺩ ﺍﻟﻤﺎﺭﺓ ﻤﻥ ﻤﻨﺨل ﺭﻗﻡ % ،200 ﺍﻟﻜﺜﺎﻓﺔ ﺍﻟﺠﺎﻓﺔ )ﻤﻴﻘﺎﺠﺭﺍﻡ/ﻡ(3 ﺍﻟﻤﺤﺘﻭﻯ ﺍﻟﻤﺎﺌﻲ )(% ﻨﺴﺒﺔ ﺍﻟﻜﻭﺍﺭﺘﺯ )(% ﻨﺴﺒﺔ ﺍﻟﻬﺎﻻﻴﺕ )(% ﻨﺴﺒﺔ ﺍﻟﻜﺎﻟﺴﺎﻴﺕ )(% ﻨﺴﺒﺔ ﺍﻟﺠﺒﺱ )(% ﻨﺴﺒﺔ ﺍﻟﻁﻴﻥ ﻭﺃﻜﺎﺴﻴﺩ ﺍﻟﺤﺩﻴﺩ )(% ﻤﻌﺎﻤل ﺍﻻﻨﻀﻐﺎﻁ )(Cc ﻤﻌﺎﻤل ﺍﻻﻨﺘﻔﺎﺥ )(Cs ﻨﺴﺒﺔ ﺘﺤﻤل ﻜﺎﻟﻴﻔﻭﺭﻨﻴﺎ )(CBR ﻤﻌﺎﻤل ﻁﺒﻘﺔ ﺍﻟﺘﺄﺴﻴﺱ )) ، (Subgrade Modulusﻤﻴﻘﺎﻨﻴﻭﺘﻥ/ﻡ(3 ﺍﻟﺘﺼﻨﻴﻑ )ﺍﻟﻨﻅﺎﻡ ﺍﻟﻤﻭﺤﺩ (Unified
][22
ﺍﻟﻘﻴﻤﺔ 13 1.60 17 49 23 21 6 1 0.2 0.018 4.2 18.3 SW-SP
4ـ 2ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﻤﻨﻁﻘﺔ ﺠﻴﺯﺍﻥ: ﺘﻘﻊ ﻤﺩﻴﻨﺔ ﺠﻴﺯﺍﻥ ﻋﻠﻰ ﺴﺎﺤل ﺍﻟﺒﺤﺭ ﺍﻷﺤﻤﺭﺍﻟﺠﻨﻭﺒﻲ ﺍﻟﻐﺭﺒﻲ ﻓﻲ ﺍﻟﻤﻤﻠﻜﺔ ﺍﻟﻌﺭﺒﻴﺔ ﺍﻟﺴﻌﻭﺩﻴﺔ ﻋﻠﻰ ﺃﺭﺽ ﻤﺭﺘﻔﻌﺔ ﻨﺴﺒﻴﹰﺎ ﻤﺭﺘﻜﺯﺓ ﻓﻭﻕ ﻤﺎ ﻴﺴﻤﻰ ﺒﺎﻟﻘﺒﺔ ﺍﻟﻤﻠﺤﻴﺔ ) ( Salt Domeﻭﺍﻟﺘﻲ ﺘﺒﻠﻎ ﻤﺴﺎﺤﺘﻬﺎ ﺤﻭﺍﻟﻲ ﺃﺭﺒﻌﺔ ﻜﻴﻠﻭﻤﺘﺭﺍﺕ ﻤﺭﺒﻌﺔ ﻋﻠﻰ ﺍﺭﺘﻔﺎﻉ ﺨﻤﺴﻴﻥ ﻤﺘﺭﹰﺍ ﻓﻭﻕ ﻤﺴﺘﻭﻯ ﺴﻁﺢ ﺍﻟﺒﺤﺭ .ﻭﺘﺤﻴﻁ ﺒﻬﺫﻩ ﺍﻟﻘﺒﺔ ﺍﻟﻤﻠﺤﻴﺔ ﻤﺴﺎﺤﺎﺕ ﻭﺍﺴﻌﺔ ﻤﻥ ﺍﻟﺴﺒﺨﺎﺕ ﻭﺍﻟﻜﺜﺒﺎﻥ ﺍﻟﺭﻤﻠﻴﺔ ﺍﻟﻤﺘﻜﻭﻨﺔ ﺒﻭﺍﺴﻁﺔ ﺍﻟﺭﻴﺎﺡ ﻭﺍﻟﺘﻲ ﺘﻤﺘﺩ ﺇﻟﻰ ﺤﻭﺍﻟﻲ 190ﻜﻴﻠﻭﻤﺘﺭﺍ ً ] .[11ﻭﻗﺩ ﺘﺴﺒﺒﺕ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺤﺩﻭﺙ ﺍﻟﺘﺼﺩﻋﺎﺕ ﻟﻠﻌﺩﻴﺩ ﻤﻥ ﺍﻟﻤﺒﺎﻨﻲ ﻓﻲ ﻤﺩﻴﻨﺔ ﺠﻴﺯﺍﻥ ﺤﻴﺙ ﺘﺭﺍﻭﺤﺕ ﻫﺫﻩ ﺍﻟﺘﺼﺩﻋﺎﺕ ﻤﻥ ﺨﻔﻴﻔﺔ ﺇﻟﻰ
ﻋﺒﺩﺍﷲ ﺒﻥ ﺇﺒﺭﺍﻫﻴﻡ ﺍﻟﻤﻬﻴﺩﺏ
54
ﻤﺘﻭﺴﻁﺔ ﺇﻟﻰ ﻜﺒﻴﺭﺓ ﻭﺫﻟﻙ ﺤﺴﺏ ﺨﺼﺎﺌﺹ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺍﻟﻤﻭﻗﻊ ،ﻭﻤﻘﺩﺍﺭ ﺍﻟﻬﺒﻭﻁ ، ﻭﺍﻟﻘﺩﺭﺓ ﺍﻟﺘﺤﻤﻠﻴﺔ ﻟﻠﺴﺒﺨﺔ].[11 ﻭﺘﺘﻤﻴﺯ ﻤﻨﻁﻘﺔ ﺠﻴﺯﺍﻥ ﻋﻤﻭﻤﹰﺎ ﺒﺘﻐﻴﺭ ﺠﻴﻭﻟﻭﺠﻴﺘﻬﺎ ﻤﻥ ﻤﻭﻗﻊ ﺇﻟﻰ ﺁﺨﺭ ﻤﻤﺎ ﻴﺘﺴﺒﺏ ﻓﻲ ﺤﺩﻭﺙ ﺍﻟﻜﺜﻴﺭ ﻤﻥ ﺍﻟﻤﺸﺎﻜل ﺍﻟﺠﻴﻭﺘﻜﻨﻴﻜﻴﺔ ﻓﻴﻬﺎ .ﺍﻟﺸﻜل ) (10ﻴﻭﻀﺢ ﺍﻟﺨﺭﻴﻁﺔ ﺍﻟﺠﻴﻭﻟﻭﺠﻴﺔ ﻟﺴﻁﺢ ﺍﻟﺠﺯﺀ ﺍﻟﺴﺎﺤﻠﻲ ﻟﻤﻨﻁﻘﺔ ﺠﻴﺯﺍﻥ .ﺘﺘﻜﻭﻥ ﺘﺭﺒﺔ ﺠﻴﺯﺍﻥ ﻤﻥ ﻨﻭﻋﻴﻥ ﺭﺌﻴﺴﻴﻥ ﻫﻤﺎ ﺘﺭﺒﺔ ﺍﻷﺭﺍﻀﻲ ﺍﻟﻤﺭﺘﻔﻌﺔ ﻭﺍﻟﺘﺭﺴﺒﺎﺕ ﺍﻟﺴﺒﺨﺔ .ﻟﻘﺩ ﺘﻜﻭﻨﺕ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻋﻨﺩﻤﺎ ﺘﺭﺴﺒﺕ ﺤﺒﻴﺒﺎﺕ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺼﻐﻴﺭﺓ ﺍﻟﺘﻲ ﻜﺎﻨﺕ ﻋﺎﻟﻘﺔ ﺒﻤﻴﺎﻩ ﺍﻟﺴﻭﺍﺤل ﻋﻨﺩ ﺍﻨﺨﻔﺎﺽ ﻁﺎﻗﺔ ﺍﻟﻤﺩ .ﻭﻴﺒﻴﻥ ﺸﻜل ) (11ﻤﻘﻁ ًﻌﺎ ﺠﺎﻨﺒ ًﻴﺎ ﻟﻠﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﺍﻟﺴﺎﺤﻠﻴﺔ ﻓﻲ ﻤﻨﻁﻘﺔ ﺠﻴﺯﺍﻥ. ﻭﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺠﻴﺯﺍﻥ ﻋﺒﺎﺭﺓ ﻋﻥ ﺜﻼﺙ ﻁﺒﻘﺎﺕ ﻫﻲ ﺍﻟﻁﺒﻘﺔ ﺍﻟﻌﻠﻭﻴﺔ ﻭﺍﻟﻤﻌﺭﻭﻓﺔ ﺒﺎﻟﻘﺸﺭﺓ ﺍﻟﺼﻠﺒﺔ ،ﺘﻠﻴﻬﺎ ﺍﻟﻁﺒﻘﺔ ﺍﻟﻭﺴﻁﻰ ﺍﻟﻘﺎﺒﻠﺔ ﻟﻺﻨﻀﻐﺎﻁ ،ﺜﻡ ﺍﻟﻁﺒﻘﺔ ﺍﻟﺴﻔﻠﻴﺔ ﺍﻟﺘﻲ ﺘﺸﻜل ﻗﺎﻋﺩﺓ ﺍﻟﺴﺒﺨﺔ .ﻭﺘﺘﻜﻭﻥ ﺍﻟﻘﺸﺭﺓ ﺍﻟﺼﻠﺒﺔ ﺍﻟﻤﻜﻭﻨﺔ ﻟﺴﻁﺢ ﺍﻟﺴﺒﺨﺔ ﻤﻥ ﺭﻤﺎل ﺠﺎﻓﺔ ﻤﺤﺘﻭﻴﺔ ﻋﻠﻰ ﺍﻟﻁﻤﻲ ،ﻭﻴﺒﻠﻎ ﺴﻤﻜﻬﺎ ﺤﻭﺍﻟﻲ ﻤﺘﺭﻴﻥ .ﺃﻤﺎ ﻤﻨﺴﻭﺏ ﺍﻟﻤﻴﺎﻩ ﺍﻟﺠﻭﻓﻴﺔ ﻓﻴﺘﺭﺍﻭﺡ ﺒﻴﻥ ﻤﺘﺭ ﺇﻟﻰ ﻤﺘﺭﻴﻥ ،ﻭﻨﺘﻴﺠﺔ ﻟﻌﻤﻠﻴﺎﺕ ﺍﻟﺘﺒﺨﺭ ﺍﻟﻤﺴﺘﻤﺭﺓ ﻓﺈﻥ ﺍﻟﻤﺤﺘﻭﻯ ﺍﻟﻤﻠﺤﻲ ﻟﻬﺫﻩ ﺍﻟﻁﺒﻘﺔ ﻜﺒﻴﺭ ﻤﻤﺎ ﻴﻜﺴﺏ ﻫﺫﻩ ﺍﻟﻁﺒﻘﺔ ﻁﺒﻴﻌﺔ ﺼﻠﺒﺔ ].[11 ﺃﻤﺎ ﺍﻟﻁﺒﻘﺔ ﺍﻟﻭﺴﻁﻰ ﺍﻟﻭﺍﻗﻌﺔ ﺘﺤﺕ ﺍﻟﻘﺸﺭﺓ ﺍﻟﺼﻠﺒﺔ ﻓﻬﻲ ﻋﺒﺎﺭﺓ ﻋﻥ ﻤﺎﺩﺓ ﻨﺎﻋﻤﺔ ﻭﻤﻔﻜﻜﺔ ﻋﻤﻭﻤﹰﺎ ،ﻭﺘﺘﻜﻭﻥ ﻤﻥ ﺭﻤﺎل ﻁﻤﻴﻴﺔ ﻟﺩﻨﺔ ،ﻭﻜﺫﻟﻙ ﻤﻥ ﺭﻤﺎل ﻁﻴﻨﻴﺔ ﻤﺤﺘﻭﻴﺔ ﻋﻠﻰ ﻤﻭﺍﺩ ﻋﻀﻭﻴﺔ .ﻭﻴﺒﻠﻎ ﺴﻤﻙ ﻫﺫﻩ ﺍﻟﻁﺒﻘﺔ ﺜﻤﺎﻨﻴﺔ ﺃﻤﺘـﺎﺭ ﺘﻘﺭﻴﺒ ﹰﺎ ﻭﺘﺘﻤﻴﺯ ﺒﻘﺎﺒﻠﻴﺘﻬﺎ ﺍﻟﻜﺒﻴﺭﺓ ﻟﻼﻨﻀﻐﺎﻁ ﺒﺎﻹﻀﺎﻓﺔ ﺇﻟﻰ ﻀﻌﻑ ﻗﺩﺭﺘﻬﺎ ﺍﻟﺘﺤﻤﻴﻠﻴﺔ .ﻭﻫﺫﻩ ﺍﻟﻁﺒﻘﺔ ﻫﻲ ﺍﻟﻁﺒﻘﺔ ﺍﻟﻤﺴﺅﻭﻟﺔ ﻋﻥ ﻤﺸﺎﻜل ﺍﻟﻬﺒﻭﻁ ﺍﻟﺫﻱ ﻴﺤﺩﺙ ﻋﻠﻰ ﺍﻟﻤﺩﻯ ﺍﻟﻁﻭﻴل ﺒﺴﺒﺏ ﻋﻤﻠﻴﺔ ﺍﻻﻨﻀﻐﺎﻁ ﺍﻟﺜﺎﻨﻭﻱ ) ( Secondary Compressionﺍﻟﻤﺭﺘﺒﻁ ﺒﺎﻟﻤﺤﺘﻭﻯ ﺍﻟﻌﻀﻭﻱ ﺍﻟﻜﺒﻴﺭ ﻨﺴﺒﻴﹰﺎ ﻟﻬﺫﻩ ﺍﻟﻁﺒﻘﺔ ﻭﺍﻟﺫﻱ ﺘﺘﺭﺍﻭﺡ ﻨﺴﺒﺘﻪ ﺒﻴﻥ %2ﺇﻟﻰ ، %8ﻭﺘﻘل ﻫﺫﻩ ﺍﻟﻨﺴﺒﺔ ﻜﻠﻤﺎ ﺍﺯﺩﺍﺩ ﺍﻟﻌﻤﻕ .ﻭﻴﻜﻭﻥ ﺍﻟﻤﺤﺘﻭﻯ ﺍﻟﻌﻀﻭﻱ ﻟﻠﺴﺒﺨﺔ ﺍﻟﺭﻤﻠﻴﺔ ﺃﻗل ﻤﻨﻪ ﻓﻲ ﺍﻟﺴﺒﺨﺔ ﺍﻟﻁﻤﻴﻴﺔ ﺍﻟﻁﻴﻨﻴﺔ ].[11
55
ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺍﻟﻤﻤﻠﻜﺔ ﺍﻟﻌﺭﺒﻴﺔ ﺍﻟﺴﻌﻭﺩﻴﺔ ....
ﻋﺒﺩﺍﷲ ﺒﻥ ﺇﺒﺭﺍﻫﻴﻡ ﺍﻟﻤﻬﻴﺩﺏ
56
ﻭﺘﻠﻲ ﺍﻟﻁﺒﻘﺔ ﺍﻟﻭﺴﻁﻰ ﺍﻟﻁﺒﻘﺔ ﺍﻟﺴﻔﻠﻴﺔ ﺍﻟﻤﻤﺜﻠﺔ ﻟﻘﺎﻋﺩﺓ ﺍﻟﺴﺒﺨﺔ ﻭﺍﻟﺘﻲ ﻟﻬﺎ ﻁﺒﻴﻌﺔ ﺼﻠﺒﺔ ،ﻭﺘﺘﻜﻭﻥ ﺒﺸﻜل ﺭﺌﻴﺴﻲ ﻤﻥ ﺭﻤﺎل ﻤﺘﻭﺴﻁﺔ ﺍﻟﻜﺜﺎﻓﺔ ﺇﻟﻰ ﻜﺜﻴﻔﺔ ،ﻭﻟﻬﺎ ﻗﺩﺭﺓ ﺘﺤﻤﻠﻴﺔ ﻋﺎﻟﻴﺔ ﻭﻗﺎﺒﻠﻴﺔ ﺇﻨﻀﻐﺎﻁ ﻤﻨﺨﻔﻀﺔ .ﻭﻴﻭﻀﺢ ﺸﻜل ) (12ﺨﺼﺎﺌﺹ ﺍﻟﻁﺒﻘﺎﺕ ﺍﻟﺜﻼﺙ ﺍﻟﺘﻲ ﺘﺘﻜﻭﻥ ﻤﻨﻬﺎ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﻤﻨﻁﻘﺔ ﺠﻴﺯﺍﻥ .ﻜﻤﺎ ﻴﺒﻴﻥ ﺠﺩﻭل )(6 ﻤﺘﻭﺴﻁ ﺍﻟﺨﺼﺎﺌﺹ ﺍﻟﺠﻴﻭﺘﻜﻨﻴﻜﻴﺔ ﻟﻠﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﻤﻨﻁﻘﺔ ﺠﻴﺯﺍﻥ ﻭﺫﻟﻙ ﻭﻓﻘ ﹰﺎ ﻟﻨﺘﺎﺌﺞ ﺍﻟﺘﺠﺎﺭﺏ ﺍﻟﻤﻌﻤﻠﻴﺔ ﻋﻠﻰ ﻋﺸﺭ ﻋﻴﻨﺎﺕ ﺤﺘﻰ ﻋﻤﻕ 15ﻡ ﺘﺤﺕ ﺴﻁﺢ ﺍﻷﺭﺽ ﻟﻜل ﻤﻥ ﺍﻟﺴﺒﺨﺔ ﺍﻟﺭﻤﻠﻴﺔ ﻭﺍﻟﺴﺒﺨﺔ ﺍﻟﻁﻤﻴﻴﺔ ﺍﻟﻁﻴﻨﻴﺔ].[11
ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺍﻟﻤﻤﻠﻜﺔ ﺍﻟﻌﺭﺒﻴﺔ ﺍﻟﺴﻌﻭﺩﻴﺔ ....
57
ﺠﺩﻭل ﺭﻗﻡ ) : (6ﺍﻟﺨﻭﺍﺹ ﺍﻟﺠﻴﻭﺘﻜﻨﻴﻜﻴﺔ ﻟﻠﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺠﻴﺯﺍﻥ
ﺍﻟﺨﺎﺼﻴﺔ ﺍﻟﻜﺜﺎﻓﺔ ﺍﻟﺠﺎﻓﺔ )ﻁﻥ/ﻡ(3 ﺍﻟﻤﺤﺘﻭﻯ ﺍﻟﻤﺎﺌﻲ )(%
ﺤﺩ ﺍﻟﺴﻴﻭﻟﺔ )% (LL
][11
ﺍﻟﺴﺒﺨﺔ ﺍﻟﺭﻤﻠﻴﺔ )ﻋﺸﺭ ﻋﻴﻨﺎﺕ ﺤﺘﻰ ﻋﻤﻕ 15ﻡ(
ﺍﻟﺴﺒﺨﺔ ﺍﻟﻁﻤﻴﻴﺔ ﺍﻟﻁﻴﻨﻴﺔ )ﻋﺸﺭ ﻋﻴﻨﺎﺕ ﺤﺘﻰ ﻋﻤﻕ 15ﻡ(
1.97
1.94-1.88
29.8-13.1 -
12 40-27
ﻋﺒﺩﺍﷲ ﺒﻥ ﺇﺒﺭﺍﻫﻴﻡ ﺍﻟﻤﻬﻴﺩﺏ
ﺤﺩ ﺍﻟﻠﺩﻭﻨﺔ )% (PL
ﻤﻌﻴﺎﺭ ﺍﻟﻠﺩﻭﻨﺔ )% (PI
-
58
36-21
ﻏﻴﺭ ﻟﺩﻨﺔ
6-4
ﻨﺴﺒﺔ ﺍﻟﻁﻤﻲ )(%
26-6
80-17
ﺍﻟﻭﺯﻥ ﺍﻟﻨﻭﻋﻲ )(Gs
2.81
2.84-2.72
20
35-25
35
33-24.7
ﻨﺴﺒﺔ ﺍﻟﺭﻤل )(% ﻨﺴﺒﺔ ﺍﻟﻁﻴﻥ )(%
ﺍﻟﺘﻤﺎﺴﻙ )C (kN/m2
ﺯﺍﻭﻴﺔ ﺍﻻﺤﺘﻜﺎﻙ ﺍﻟﺩﺍﺨﻠﻲ )φ (degrees
95-55 7-0
80-10 25-3
4ـ 3ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺍﻟﻤﻨﻁﻘﺔ ﺍﻟﻐﺭﺒﻴﺔ : ﺘﺘﻜﻭﻥ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻋﻠﻰ ﻁﻭل ﺍﻟﺴﺎﺤل ﺍﻟﻐﺭﺒﻲ ﻤﻥ ﺍﻟﻤﻤﻠﻜﺔ ﺍﻟﻌﺭﺒﻴﺔ ﺍﻟﺴﻌﻭﺩﻴﺔ ﻓﻲ ﻤﻌﻅﻤﻬﺎ ﻤﻥ ﺘﺭﺒﺔ ﺤﺒﻴﺒﻴﺔ ﻤﺘﻤﺎﺴﻜﺔ ﺃﻭ ﻤﺘﻔﻜﻜﺔ ،ﻭﺤﺒﻴﺒﺎﺘﻬﺎ ﻤﻜﻭﻨﺔ ﻤﻥ ﺨﻠﻴﻁ ﻤﻥ ﺍﻟﺭﻤل ﺃﻭ ﺍﻟﻁﻤﻲ ﻤﻊ ﺍﺨﺘﻼﻑ ﻓﻲ ﺍﻟﻜﺜﺎﻓﺔ ﻭﺍﻟﻤﺤﺘﻭﻴﺎﺕ ﻭﺩﺭﺠﺔ ﺍﻟﺘﻼﺤﻡ ﻤﻥ ﻤﻭﻗﻊ ﺇﻟﻰ ﺁﺨﺭ .ﻜﻤﺎ ﺃﻥ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺒﻌﺽ ﺍﻟﻤﻭﺍﻗﻊ ﺘﺘﻜﻭﻥ ﻤﻥ ﺨﻠﻴﻁ ﻤﻥ ﺍﻟﺭﻤل ﻭﺍﻟﻁﻤﻲ ﻭﺍﻟﺤﺼﻰ ﺒﻨﺴﺏ ﻤﺨﺘﻠﻔﺔ ،ﻭﻋﻤﻭﻤﺎ ﻓﺎﻥ ﺍﻟﺘﺭﺴﺒﺎﺕ ﺍﻟﺤﺼﻭﻴﺔ ﺃﻜﺜﺭ ﺘﻭﺍﺠﺩﹰﺍ ﻓﻲ ﺍﻟﺴﺒﺨﺔ ﺍﻟﻘﺎﺭﻴﺔ ﻤﻨﻬﺎ ﻓﻲ ﺍﻟﺴﺒﺨﺔ ﺍﻟﺴﺎﺤﻠﻴﺔ].[23 ﻭﻴُﻌﺘﻘﺩ ﺒﺄﻥ ﻋﻤﻠﻴﺔ ﺘﻜﻭﻥ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺍﻟﻤﻨﻁﻘﺔ ﺍﻟﻐﺭﺒﻴﺔ ﻗﺩ ﺒﺩﺃﺕ ﺒﺘﻜﻭﻥ ﻤﺎ ﻴُﺴﻤﻰ ﺒﺎﻟﺒﺤﻴﺭﺍﺕ ) (Lagoonsﺍﻟﻨﺎﺘﺠﺔ ﻤﻥ ﻏﻤﺭ ﻤﻴﺎﻩ ﺍﻟﺒﺤﺭ ﻟﻠﻴﺎﺒﺴﺔ ،ﻭﻁﻭﻗﺕ ﻫﺫﻩ ﺍﻟﺒﺤﻴﺭﺍﺕ ﺘﺩﺭﻴﺠﻴﺎ ﺒﺎﻟﺴﻼﺴل ﺍﻟﺼﺨﺭﻴﺔ ﺍﻟﺘﻲ ﺤﺠﺯﺕ ﻤﻴﺎﻫﻬﺎ .ﻭﺒﻌﺩ ﺫﻟﻙ ﺘﻭﻓﺭﺕ ﺍﻟﻅﺭﻭﻑ ﺍﻟﻤﻨﺎﺨﻴﺔ ﺍﻟﻤﻼﺌﻤﺔ ﻟﺘﺒﺨﻴﺭ ﻫﺫﻩ ﺍﻟﻤﻴﺎﻩ ﻭﺘﺭﺴﺏ ﺍﻟﺘﺭﺴﺒﺎﺕ ﺍﻟﺒﺤﺭﻴﺔ ﺍﻟﺘﻲ ﺍﺨﺘﻠﻁﺕ ﻤﻊ ﺘﺭﺒﺔ ﺍﻟﻴﺎﺒﺴﺔ ،ﻭﺒﺎﺴﺘﻤﺭﺍﺭ ﻋﻤﻠﻴﺔ ﺍﻟﺘﺒﺨﺭ ﻤﻊ ﺘﺭﺍﺠﻊ ﻤﻴﺎﻩ ﺍﻟﺒﺤﺭ، ﺘﺭﺴﺒﺕ ﺍﻟﻤﻭﺍﺩ ﺍﻟﻤﻜﻭﻨﺔ ﻟﻠﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﺍﻟﺘﻲ ﺘﻜﺘﺴﺏ ﺘﻤﺎﺴﻜﻬﺎ ﻤﻥ ﺍﻟﻤﻭﺍﺩ ﺍﻟﻼﺤﻤﺔ ﻭﻫﻲ ﺍﻷﻤﻼﺡ ﺍﻟﻤﺨﺘﻠﻔﺔ ﻜﺎﻟﻬﺎﻻﻴﺕ ﻭﺍﻟﺠﺒﺱ ﻭﺍﻟﻜﺎﻟﺴﺎﻴﺕ ] .[23ﻭﺴﻴﺘﻡ ﺍﻟﺤﺩﻴﺙ ﻋﻥ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﻜل ﻤﻥ ﺠﺩﺓ ﻭﺃﺒﺤﺭ ﻭﺍﻟﻠﻴﺙ ﻓﻲ ﺍﻟﻤﻨﻁﻘﺔ ﺍﻟﻐﺭﺒﻴﺔ.
59
ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺍﻟﻤﻤﻠﻜﺔ ﺍﻟﻌﺭﺒﻴﺔ ﺍﻟﺴﻌﻭﺩﻴﺔ ....
4ـ 3ـ 1ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺠﺩﺓ : ﺘﻭﺠﺩ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺍﻟﺠﺯﺀ ﺍﻟﺸﻤﺎﻟﻲ ﻤﻥ ﻤﺩﻴﻨﺔ ﺠﺩﺓ ﻓﻭﻕ ﺍﻟﺘﻜﻭﻴﻨﺎﺕ ﺍﻟﺼﺨﺭﻴﺔ ﻟﻠﺤﺠﺭ ﺍﻟﺠﻴﺭﻱ ،ﻜﻤﺎ ﺘﻭﺠﺩ ﻓﻲ ﺒﻌﺽ ﺍﻷﺠﺯﺍﺀ ﻓﻭﻕ ﻁﺒﻘﺎﺕ ﻁﻴﻨﻴﺔ ﺃﻭ ﺭﻤﻠﻴﺔ ﻁﻤﻴﻴﺔ .ﺃﻤﺎ ﻓﻲ ﺍﻟﺠﺯﺀ ﺍﻟﺠﻨﻭﺒﻲ ﻓﺎﻥ ﺍﻟﺘﺭﺴﺒﺎﺕ ﺍﻟﺴﺒﺨﻴﺔ ﻨﺘﺠﺕ ﻤﻥ ﺘﺂﻜل ﺍﻟﺼﺨﻭﺭ ﺍﻟﻜﺭﻴﺴﺘﺎﻟﻴﺔ ﻭﺍﻟﺠﻴﺭﻴﺔ ،ﻭﻤﻥ ﺍﻟﺘﺭﺴﺒﺎﺕ ﺍﻟﺒﺤﺭﻴﺔ ﺍﻟﻘﺭﻴﺒﺔ ﻤﻥ ﺍﻟﺸﺎﻁﺊ ﺍﻟﻤﺨﺘﻠﻁﺔ ﻤﻊ ﺍﻟﻁﻤﻲ ﻭﺍﻟﺭﻤل ﻭﺍﻟﺤﺼﻰ. ﻭﺘﺘﻜﻭﻥ ﺭﺴﻭﺒﻴﺎﺕ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺠﺩﺓ ﻤﻥ ﺜﻼﺙ ﻁﺒﻘﺎﺕ :ﺍﻟﻁﺒﻘﺔ ﺍﻟﻌﻠﻴﺎ )ﺍﻟﻘﺸﺭﺓ( ﻭﺍﻟﺘﻲ ﻴﺒﻠﻎ ﺴﻤﻜﻬﺎ ﻤﺘﺭﻴﻥ ،ﻭﺍﻟﻁﺒﻘﺔ ﺍﻟﻭﺴﻁﻰ ﺍﻟﻘﺎﺒﻠﺔ ﻟﻼﻨﻀﻐﺎﻁ ﻭﻴﺒﻠﻎ ﺴﻤﻜﻬﺎ ﺴﺘﺔ ﺃﻤﺘﺎﺭ ،ﺜﻡ ﺘﻠﻴﻬﺎ ﺍﻟﻁﺒﻘﺔ ﺍﻟﺴﻔﻠﻰ ﻭﺍﻟﺘﻲ ﺘﻤﺜل ﻗﺎﻋﺩﺓ ﺍﻟﺴﺒﺨﺔ ﻭﻴﺒﻠﻎ ﺴﻤﻜﻬﺎ ﻤﺘﺭﻴﻥ ﺘﻘﺭﻴﺒﹰﺎ. ﻭﺘﻭﺠﺩ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﻤﺩﻴﻨﺔ ﺠﺩﺓ ﻓﻲ ﻤﻨﺎﻁﻕ ﺍﻟﺨﺎﻟﺩﻴﺔ ﻭﺍﻟﺴﻼﻤﺔ ﻭﺍﻟﺤﻤﺭﺍﺀ ﻭﺍﻟﺭﻭﻴﺱ ﻭﺍﻟﻜﻭﺭﻨﻴﺵ ﻭﻤﻴﻨﺎﺀ ﺠﺩﺓ .ﻭﺘﺸﺘﺭﻙ ﻫﺫﻩ ﺍﻟﺴﺒﺨﺎﺕ ﺒﺄﻥ ﺍﻟﻁﺒﻘﺔ ﺍﻟﻤﻤﺘﺩﺓ ﻤﻥ ﺍﻟﺴﻁﺢ ﺇﻟﻰ ﻋﻤﻕ ﻤﺘﺭﻴﻥ ﺘﻘﺭﻴﺒﹰﺎ ﺘﺘﻜﻭﻥ ﻤﻥ ﺭﻤل ﻀﻌﻴﻑ ﺍﻟﺘﺩﺭﺝ ﺇﻟﻰ ﻤﺘﺩﺭﺝ ﺍﻟﺤﺒﻴﺒﺎﺕ ﻤﻊ ﺒﻌﺽ ﺍﻟﻁﻤﻲ ﻭﺘﺼﻨﻴﻑ ﺍﻟﺘﺭﺒﺔ ﻫﻭ SP ، SWﻭ SMﺤﺴﺏ ﺘﺼﻨﻴﻑ ﺍﻟﻨﻅﺎﻡ ﺍﻟﻤﻭﺤﺩ .ﻭﺒﺎﻟﻨﺴﺒﺔ ﻟﻤﻨﺴﻭﺏ ﺍﻟﻤﻴﺎﻩ ﺍﻟﺠﻭﻓﻴﺔ ﻓﺈﻨﻪ ﻴﺘﺭﺍﻭﺡ ﺒﻴﻥ 20ﺴﻡ ﻭ 1.5 ﻤﺘﺭ .ﻭﻓﻲ ﺴﺒﺨﺔ ﺍﻟﺴﻼﻤﺔ ﻭﺍﻟﺘﻲ ﺘﻌﺘﺒﺭ ﻭﺍﺩﻴﹰﺎ ،ﺘﻜﻭﻥ ﺍﻟﻤﻴﺎﻩ ﺍﻟﺠﻭﻓﻴﺔ ﻤﻼﻤﺴﺔ ﻟﻠﺴﻁﺢ ﺘﻘﺭﻴﺒﺎ ،ﻭﻴﺘﺯﺍﻴﺩ ﻋﻤﻕ ﻤﻨﺴﻭﺏ ﺍﻟﻤﻴﺎﻩ ﺍﻟﺠﻭﻓﻴﺔ ﺘﺩﺭﻴﺠﻴﹰﺎ ﻜﻠﻤﺎ ﺍﺘﺠﻬﻨﺎ ﺇﻟﻰ ﺍﻟﺩﺍﺨل ﺒﻌﻴﺩﹰﺍ ﻋﻥ ﺍﻟﺴﺎﺤل] .[23ﻭﺘﺒﻴﻥ ﺍﻷﺸﻜﺎل ) (13ﻭ) (14ﻭ) (15ﻤﻘﺎﻁﻊ ﺠﺎﻨﺒﻴﺔ ﻟﻠﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﻤﻨﺎﻁﻕ ﺍﻟﺨﺎﻟﺩﻴﺔ ﻭﺍﻟﺴﻼﻤﺔ ﻭﺍﻟﺤﻤﺭﺍﺀ ﻭﺍﻟﺭﻭﻴﺱ ﻭﺍﻟﻜﻭﺭﻨﻴﺵ ﻭﻤﻴﻨﺎﺀ ﺠﺩﺓ. ﻭﻴﻭﻀﺢ ﺠﺩﻭل ) (7ﻗﻴﻡ ﺍﻟﻤﺤﺘﻭﻯ ﺍﻟﻤﺎﺌﻲ ﻭﺍﻟﺴﻌﺔ ﺍﻟﺘﺤﻤﻠﻴﺔ ﻟﻜل ﺴﺒﺨﺔ ﻤﻥ
ﻋﺒﺩﺍﷲ ﺒﻥ ﺇﺒﺭﺍﻫﻴﻡ ﺍﻟﻤﻬﻴﺩﺏ
60
ﺴﺒﺨﺎﺕ ﻤﺩﻴﻨﺔ ﺠﺩﺓ ،ﺤﻴﺙ ﻴﺘﺭﺍﻭﺡ ﺍﻟﻤﺤﺘﻭﻯ ﺍﻟﻤﺎﺌﻲ ﻟﻬﺫﻩ ﺍﻟﺴﺒﺨﺎﺕ ﺒﺸﻜل ﻋﺎﻡ ﺒﻴﻥ %5ﻭ % 35ﺒﻤﺘﻭﺴﻁ ﻤﻘﺩﺍﺭﻩ .% 20ﻭﺘﺘﺭﺍﻭﺡ ﺍﻟﺴﻌﺔ ﺍﻟﺘﺤﻤﻠﻴﺔ ﺒﻴﻥ 0.10 ﻜﺠﻡ/ﺴﻡ 2ﻭ 0.70ﻜﺠﻡ/ﺴﻡ 2ﺒﻨﺎ ًﺀ ﻋﻠﻰ ﻤﺘﻭﺴﻁ ﻋﺩﺩ ﺍﻟﻀﺭﺒﺎﺕ ﻻﺨﺘﺒﺎﺭ ﺍﻻﺨﺘﺭﺍﻕ ﺍﻟﻘﻴﺎﺴﻲ) .[23] (SPTﻭﺘﺯﺩﺍﺩ ﺍﻟﺴﻌﺔ ﺍﻟﺘﺤﻤﻠﻴﺔ ﻜﻠﻤﺎ ﺍﺯﺩﺍﺩ ﺍﻟﻌﻤﻕ ﻤﻊ ﺘﻭﺍﺠﺩ ﺍﻟﺘﻜﻭﻴﻨﺎﺕ ﺍﻟﺼﺨﺭﻴﺔ ﺤﻴﺙ ﻗﺩ ﺘﺼل ﺇﻟﻰ 2.5ﻜﺠﻡ/ﺴﻡ ، 2ﻋﻠﻤﹰﺎ ﺒﺄﻥ ﺍﻟﻘﻴﻡ ﺍﻟﻤﺫﻜﻭﺭﺓ ﻓﻲ ﺍﻟﺠﺩﻭل ﻫﻲ ﻟﻠﻁﺒﻘﺔ ﺍﻟﻤﻤﺘﺩﺓ ﻤﻥ ﺍﻟﺴﻁﺢ ﺇﻟﻰ ﻋﻤﻕ 2ﻤﺘﺭ ﺘﻘﺭﻴﺒﹰﺎ ] .[23ﻭﺘﻌﺘﺒﺭ ﺍﻟﺴﻌﺔ ﺍﻟﺘﺤﻤﻴﻠﻴﺔ ﻟﻠﻁﺒﻘﺔ ﺍﻟﻌﻠﻴﺎ ) 2ﻤﺘﺭ( ﻀﻌﻴﻔﺔ ﻭﻟﻜﻥ ﻴﻤﻜﻥ ﺘﺤﺴﻴﻨﻬﺎ ﻋﻥ ﻁﺭﻴﻕ ﻤﻌﺎﻟﺠﺔ ﺍﻟﺘﺭﺒﺔ ﺒﻭﺍﺴﻁﺔ ﺍﻟﺩﻤﻙ ﻭﺒﺎﻟﺘﺎﻟﻲ ﻴﻤﻜﻥ ﺍﺴﺘﺨﺩﺍﻤﻬﺎ ﻜﻤﺎﺩﺓ ﺭﺩﻡ ﺃﻴﻀﹰﺎ. ﺠﺩﻭل) : (7ﺍﻟﺴﻌﺔ ﺍﻟﺘﺤﻤﻴﻠﻴﺔ ﻭﺍﻟﻤﺤﺘﻭﻯ ﺍﻟﻤﺎﺌﻲ ﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﻤﺩﻴﻨﺔ ﺠﺩﺓ ﺍﻟﺨﺎﺼﻴﺔ ﺍﻟﺴﻌﺔ ﺍﻟﺘﺤﻤﻴﻠﻴﺔ )(SPT
ﻜﺠﻡ/ﺴﻡ2 ﺍﻟﻤﺤﺘﻭﻯ
ﺍﻟﻤﺎﺌﻲ )(%
ﺍﻟﺨﺎﻟﺩﻴﺔ
ﺍﻟﺴﻼﻤﺔ
ﺍﻟﺤﻤﺭﺍﺀ
ﺍﻟﺭﻭﻴﺱ
ﺍﻟﻜﻭﺭﻨﻴﺵ
][23
ﻤﻴﻨﺎﺀ ﺠﺩﺓ
0.5 -0.18
0.67-0.6
0.6 -0.33
0.45 -0.3
0.7 -0.15
0.6 -0.1
32 - 15
25 - 9
32 - 8
32 - 8
28 - 5
35 - 10
61
ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺍﻟﻤﻤﻠﻜﺔ ﺍﻟﻌﺭﺒﻴﺔ ﺍﻟﺴﻌﻭﺩﻴﺔ ....
ﻋﺒﺩﺍﷲ ﺒﻥ ﺇﺒﺭﺍﻫﻴﻡ ﺍﻟﻤﻬﻴﺩﺏ
62
63
ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺍﻟﻤﻤﻠﻜﺔ ﺍﻟﻌﺭﺒﻴﺔ ﺍﻟﺴﻌﻭﺩﻴﺔ ....
ﻋﺒﺩﺍﷲ ﺒﻥ ﺇﺒﺭﺍﻫﻴﻡ ﺍﻟﻤﻬﻴﺩﺏ
64
ﻭﻴﻭﻀﺢ ﺠﺩﻭل ) (8ﻗﻴﻡ ﺍﻟﺭﻗﻡ ﺍﻟﻬﻴﺩﺭﻭﺠﻴﻨﻲ ﻭﺘﺭﻜﻴﺯ ﻜل ﻤﻥ ﺍﻟﻜﺒﺭﻴﺘﺎﺕ ﻭﺍﻟﻜﻠﻭﺭﻴﺩﺍﺕ ﻓﻲ ﻜل ﺴﺒﺨﺔ ﻤﻥ ﺴﺒﺨﺎﺕ ﺠﺩﺓ .ﻭﺘﺒﻴﻥ ﻗﻴﻡ ﺍﻟﺭﻗﻡ ﺍﻟﻬﻴﺩﺭﻭﺠﻴﻨﻲ ﻗﻠﻭﻴﺔ ﺍﻟﻤﺎﺀ ﻨﺴﺒﻴﹰﺎ ﻓﻲ ﻤﻌﻅﻡ ﺍﻟﺴﺒﺨﺎﺕ .ﻭﻗﺩ ﻜﺎﻥ ﻤﺎﺀ ﺍﻟﺒﺤﺭ ﺍﻟﺴﺒﺏ ﺍﻟﺭﺌﻴﺱ ﻓﻲ ﺘﺯﻭﻴﺩ ﻫﺫﻩ ﺍﻟﺴﺒﺨﺎﺕ ﺒﺄﻤﻼﺡ ﺍﻟﻜﺒﺭﻴﺘﺎﺕ ﻭﺍﻟﻜﻠﻭﺭﻴﺩﺍﺕ ﻭﺨﺎﺼﺔ ﺍﻟﻁﺒﻘﺎﺕ ﺍﻟﻌﻠﻴﺎ ﻤﻨﻬﺎ ﻭﺒﺎﻟﺘﺎﻟﻲ ﺍﻟﻌﻤل ﻋﻠﻰ ﺘﻘﻠﻴل ﺴﻌﺘﻬﺎ ﺍﻟﺘﺤﻤﻴﻠﻴﺔ ﺒﺴﺒﺏ ﻀﻌﻑ ﺍﻟﺭﻭﺍﺒﻁ ﺒﻴﻥ ﺤﺒﻴﺒﺎﺕ ﺍﻟﺘﺭﺒﺔ ﻟﻭﺠﻭﺩ ﻫﺫﻩ ﺍﻷﻤﻼﺡ. 4ـ 3ـ 2ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺃﺒﺤﺭ : ﺘﻘﻊ ﺃﺒﺤﺭ ﺸﻤﺎل ﻤﺩﻴﻨﺔ ﺠﺩﺓ ﻋﻠﻰ ﺍﻟﺒﺤﺭ ﺍﻷﺤﻤﺭ ،ﻭﺘﺼﻨﻑ ﺴﺒﺨﺘﻬﺎ ﺒﺄﻨﻬﺎ ﺴﺒﺨﺔ ﺴﺎﺤﻠﻴﺔ .ﻭﻗﺩ ﺘﻡ ﺘﻁﻭﻴﺭ ﺃﺠﺯﺍﺀ ﻜﺒﻴﺭﺓ ﻤﻥ ﻫﺫﻩ ﺍﻟﺴﺒﺨﺔ ﻭﺠﻌﻠﻬﺎ ﻤﻨﺎﻁﻕ ﺴﻜﻨﻴﺔ. ﻭﺘﺘﺤﺩﺩ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺃﺒﺤﺭ ﺒﻤﻨﻁﻘﺘﻴﻥ ﺭﺌﻴﺴﺘﻴﻥ ﻫﻤﺎ :ﻤﻨﻁﻘﺔ ﺍﻟﺴﺒﺨﺔ ﺍﻟﻁﻴﻨﻴﺔ، ﻭﻤﻨﻁﻘﺔ ﺍﻟﺴﺒﺨﺔ ﺍﻟﺭﻤﻠﻴﺔ .ﻭﻜﻠﺘﺎ ﺍﻟﻤﻨﻁﻘﺘﻴﻥ ﻤﻭﺍﺯﻴﺘﺎﻥ ﻟﺴﺎﺤل ﺍﻟﺒﺤﺭ ﺍﻷﺤﻤﺭ، ﻭﺍﻟﻤﻨﻁﻘﺔ ﺍﻷﻭﻟﻰ ﺃﻋﺭﺽ ﻤﻥ ﺍﻟﺜﺎﻨﻴﺔ )ﺸﻜل .(16ﻭﻫﻨﺎﻙ ﻤﻨﻁﻘﺔ ﺜﺎﻟﺜﺔ ﺜﺎﻨﻭﻴﺔ ﻋﺒﺎﺭﺓ ﻋﻥ ﻤﺴﺎﺤﺔ ﻁﻴﻨﻴﺔ ﺘﻐﻁﻲ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻭﺘﻌﺭﻑ ﺒﺘﻬﺎﻤﺔ .ﻭﺍﻟﺠﺯﺀ ﺍﻟﻐﺭﺒﻲ ﻤﻥ ﺴﺒﺨﺔ ﺃﺒﺤﺭ ﻤﺤﺎﻁ ﺒﺸﺭﻴﺤﺔ ﺴﺎﺤﻠﻴﺔ ﻴﺒﻠﻎ ﻋﺭﻀﻬﺎ 500ﻤﺘﺭﹰﺍ ﻭﺘﺘﻤﻴﺯ ﺒﺎﺤﺘﻭﺍﺌﻬﺎ ﻋﻠﻰ ﺍﻟﺤﺠﺭ ﺍﻟﺠﻴﺭﻱ ].[25 ﺠﺩﻭل) : (8ﺘﺭﻜﻴﺯ ﺍﻟﻜﺒﺭﻴﺘﺎﺕ ﻭﺍﻟﻜﻠﻭﺭﻴﺩﺍﺕ ﻓﻲ ﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﻤﻨﻁﻘﺔ ﺠﺩﺓ ﺍﻟﺨﺎﺼﻴﺔ ﺍﻟﺭﻗﻡ ﺍﻟﻬﻴﺩﺭﻭﺠﻴﻨﻲ ﺍﻟﻜﺒﺭﻴﺘﺎﺕ )ﺠﺯﺀ ﻓﻲ ﺍﻟﻤﻠﻴﻭﻥ( ﺍﻟﻜﻠﻭﺭﻴﺩﺍﺕ )ﺠﺯﺀ ﻓﻲ ﺍﻟﻤﻠﻴﻭﻥ(
* ﻟﻠﻤﺎﺀ
][23
ﺍﻟﺨﺎﻟﺩﻴﺔ
ﺍﻟﺴﻼﻤﺔ
ﺍﻟﺤﻤﺭﺍﺀ
ﺍﻟﺭﻭﻴﺱ
ﺍﻟﻜﻭﺭﻨﻴﺵ
ﻤﻴﻨﺎﺀ ﺠﺩﺓ
8 - 7.6
8.3
9 - 5.6
8.4
8.7 - 7.8
8.7 - 7.4
* 2880
* 2920
** 1400
** 3900
* 24400
* 30910
** 4800
** 9200
2800
-
* 2925 - 14750 * 24080
* 4939 * 8599
* 3108 ** 400 * 5673 ** %0.01
** ﻟﻠﺘﺭﺒﺔ
* 1848 * 2664
65
ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺍﻟﻤﻤﻠﻜﺔ ﺍﻟﻌﺭﺒﻴﺔ ﺍﻟﺴﻌﻭﺩﻴﺔ ....
ﻭﻴﻭﻀﺢ ﺸﻜل ) (17ﻭﺼﻑ ﻟﻁﺒﻘﺎﺕ ﺍﻟﺴﺒﺨﺔ ﺍﻟﻁﻤﻴﻴﺔ ﻭﺍﻟﺴﺒﺨﺔ ﺍﻟﺭﻤﻠﻴﺔ ﻓﻲ ﺃﺒﺤﺭ .ﺤﻴﺙ ﻴﺘﺭﺍﻭﺡ ﺴﻤﻙ ﺍﻟﻘﺸﺭﺓ ﻓﻲ ﻤﻨﻁﻘﺔ ﺍﻟﺴﺒﺨﺔ ﺍﻟﻁﻴﻨﻴﺔ ﺒﻴﻥ 0.6ﻭ 0.8ﻤﺘﺭﹰﺍ ،ﻭﺘﺭﺘﻜﺯ ﻫﺫﻩ ﺍﻟﻘﺸﺭﺓ ﻋﻠﻰ ﻁﺒﻘﺔ ﻟﻴﻨﺔ ﻤﺤﺘﻭﻴﺔ ﻋﻠﻰ ﻁﻴﻥ ﻁﻤﻴﻲ ﺭﻤﻠﻲ ﺭﻤﺎﺩﻱ ﺍﻟﻠﻭﻥ ،ﻭﻴﺒﻠﻎ ﺴﻤﻙ ﻫﺫﻩ ﺍﻟﻁﺒﻘﺔ ﻤﺘﺭﻴﻥ ﺘﻘﺭﻴﺒﹰﺎ .ﻭﺘﻠﻴﻬﺎ ﻁﺒﻘﺔ ﺼﻠﺒﺔ ﻨﻭﻋﹰﺎ ﻤﺎ ﻤﻜﻭﻨﺔ ﻤﻥ ﻁﻴﻥ ﻁﻤﻴﻲ ﺭﻤﻠﻲ ﺒﻨﻲ ﺍﻟﻠﻭﻥ ،ﻭﺘﺭﺘﻜﺯ ﻫﺫﻩ ﺍﻟﻁﺒﻘﺔ ﻋﻠﻰ ﻁﺒﻘﺔ ﺃﺨﺭﻯ ﻤﺘﻭﺴﻁﺔ ﺍﻟﻜﺜﺎﻓﺔ ﻤﻜﻭﻨﺔ ﻤﻥ ﺭﻤل ﻤﺤﺘ ٍﻭ ﻋﻠﻰ ﺍﻟﻜﺭﺒﻭﻨﺎﺕ ﻤﻊ ﺍﻟﺤﺼﻰ ،ﺃﻤﺎ ﻤﻨﺴﻭﺏ ﺍﻟﻤﻴﺎﻩ ﺍﻟﺠﻭﻓﻴﺔ ﻓﻴﺘﺭﺍﻭﺡ ﺒﻴﻥ 0.6ﻭ 1.2ﻤﺘﺭﹰﺍ. ﺃﻤﺎ ﻤﻨﻁﻘﺔ ﺍﻟﺴﺒﺨﺔ ﺍﻟﺭﻤﻠﻴﺔ ،ﻓﺈﻥ ﺍﻟﻁﺒﻘﺔ ﺍﻟﺴﻁﺤﻴﺔ ﻟﻬﺎ ﺘﺘﻤﻴﺯ ﺒﺄﻨﻬﺎ ﻁﺒﻘﺔ ﻤﻔﻜﻜﺔ ﺠﺩﹰﺍ ﻭﻫﻲ ﻋﺒﺎﺭﺓ ﻋﻥ ﺭﻤل ﻁﻤﻴﻲ ﻤﺤﺘ ٍﻭ ﻋﻠﻰ ﺍﻟﻜﺭﺒﻭﻨﺎﺕ ،ﻭﻴﺘﺭﺍﻭﺡ ﺴﻤﻜﻬﺎ ﺒﻴﻥ
ﻋﺒﺩﺍﷲ ﺒﻥ ﺇﺒﺭﺍﻫﻴﻡ ﺍﻟﻤﻬﻴﺩﺏ
66
0.6ﻭ 1.2ﻤﺘﺭﹰﺍ ﺘﻘﺭﻴﺒﹰﺎ .ﻭﺘﻠﻲ ﻫﺫﻩ ﺍﻟﻁﺒﻘﺔ ﻁﺒﻘﺔ ﻤﺘﻭﺴﻁﺔ ﺍﻟﻜﺜﺎﻓﺔ ﻋﺒﺎﺭﺓ ﻋﻥ ﺭﻤل ﻤﺤﺘ ٍﻭ ﻋﻠﻰ ﺍﻟﻜﺭﺒﻭﻨﺎﺕ ﻤﻊ ﺍﻟﺤﺼﻰ ،ﻭﺘﺭﺘﻜﺯ ﻋﻠﻰ ﺍﻟﺤﺠﺭ ﺍﻟﺠﻴﺭﻱ .ﺃﻤﺎ ﻤﻨﺴﻭﺏ ﺍﻟﻤﻴﺎﻩ ﺍﻟﺠﻭﻓﻴﺔ ﻓﻴﺼل ﺇﻟﻰ 1.2ﻤﺘﺭﹰﺍ ﻭﻗﺩ ﻴﺯﻴﺩ ﻋﻠﻰ ﺫﻟﻙ ].[25
ﺸﻜل ) : (17ﻭﺼﻑ ﻟﻁﺒﻘﺎﺕ ﺍﻟﺴﺒﺨﺔ ﺍﻟﻁﻴﻨﻴﺔ ﻭﺍﻟﺴﺒﺨﺔ ﺍﻟﺭﻤﻠﻴﺔ ﻓﻲ ﺃﺒﺤﺭ ]. [24
ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺍﻟﻤﻤﻠﻜﺔ ﺍﻟﻌﺭﺒﻴﺔ ﺍﻟﺴﻌﻭﺩﻴﺔ ....
67
ﻭﻴﻭﻀﺢ ﺠﺩﻭل ) (9ﺍﻟﺨﻭﺍﺹ ﺍﻟﺠﻴﻭﺘﻜﻨﻴﻜﻴﺔ ﻟﻠﺴﺒﺨﺔ ﺍﻟﻁﻴﻨﻴﺔ ﻓﻲ ﺃﺒﺤﺭ ﻓﻲ ﺍﻟﻁﺒﻘﺎﺕ ﺍﻟﺜﻼﺙ ﺍﻟﻌﻠﻴﺎ ﻭﻫﻲ ﺍﻟﻘﺸﺭﺓ ﻭﺍﻟﺘﻲ ﻴﺒﻠﻎ ﺴﻤﻜﻬﺎ 0.8 - 0.6ﻤﺘﺭﹰﺍ ،ﻭﻁﺒﻘﺔ ﺍﻟﻁﻴﻥ ﺍﻟﻠﻴﻥ ﻭﺍﻟﺘﻲ ﻴﺒﻠﻎ ﺴﻤﻜﻬﺎ ﺤﻭﺍﻟﻲ 1.5ﻤﺘﺭﹰﺍ ،ﻭﻁﺒﻘﺔ ﺍﻟﻁﻴﻥ ﺍﻟﻘﺎﺴﻲ ﻭﺍﻟﺘﻲ ﻴﺒﻠﻎ ﺴﻤﻜﻬﺎ ﺤﻭﺍﻟﻲ ﺜﻼﺜﺔ ﺃﻤﺘﺎﺭ )ﺸﻜل .(16ﻭﻴﺘﻀﺢ ﻤﻥ ﻫﺫﺍ ﺍﻟﺠﺩﻭل ﺃﻥ ﻗﻴﻤﺔ ﻗﻭﺓ ﺍﻟﻘﺹ ﺍﻟﻨﺎﺘﺠﺔ ﻤﻥ ﺘﺠﺭﺒﺔ ﺍﻟﻤﺭﻭﺤﺔ ﻓﻲ ﺍﻟﺤﻘل ﻟﻠﻘﺸﺭﺓ ﺍﻟﻌﻠﻴﺎ ﻭﻜﺫﻟﻙ ﻗﻴﻤﺔ ﻤﻘﺎﻭﻤﺔ ﺍﻟﻤﺨﺭﻭﻁ ﻟﻬﺎ ﺃﻋﻠﻰ ﻤﻥ ﻨﻅﻴﺭﺍﺘﻬﺎ ﻟﻁﺒﻘﺔ ﺍﻟﻁﻴﻥ ﺍﻟﻠﻴﻥ ﻭﻴﺭﺠﻊ ﺴﺒﺏ ﺫﻟﻙ ﻟﻌﻤﻠﻴﺔ ﺍﻟﺘﺠﻔﻴﻑ ﺍﻟﺘﻲ ﺘﺘﻌﺭﺽ ﻟﻬﺎ ﺍﻟﻘﺸﺭﺓ ﺤﻴﺙ ﺘﺩل ﻗﻴﻡ ﺤﺩ ﺍﻟﻠﺩﻭﻨﺔ ﺍﻟﻘﺭﻴﺒﺔ ﻤﻥ ﺍﻟﻤﺤﺘﻭﻯ ﺍﻟﻤﺎﺌﻲ ﻋﻠﻰ ﺤﺩﻭﺙ ﻋﻤﻠﻴﺔ ﺍﻟﺘﺠﻔﻴﻑ ﻟﻬﺎ .ﻜﻤﺎ ﻴﺘﻀﺢ ﻤﻥ ﺍﻟﺠﺩﻭل ﺃﻴﻀﹰﺎ ﺃﻥ ﻁﺒﻘﺔ ﺍﻟﻁﻴﻥ ﺍﻟﻠﻴﻥ ﻫﻲ ﺃﻜﺜﺭ ﻫﺫﻩ ﺍﻟﻁﺒﻘﺎﺕ ﺍﻨﻀﻐﺎﻁﹰﺎ ) ﻗﻴﻡ ﻤﻌﺎﻤل ﺍﻻﻨﻀﻐﺎﻁ ﻟﻬﺎ ﻋﺎﻟﻴﺔ (. ﺠﺩﻭل ﺭﻗﻡ ) : (9ﺍﻟﺨﻭﺍﺹ ﺍﻟﺠﻴﻭﺘﻜﻨﻴﻜﻴﺔ ﻟﻠﺴﺒﺨﺔ ﺍﻟﻁﻴﻨﻴﺔ ﻓﻲ ﺃﺒﺤﺭ ﺍﻟﺨﺎﺼﻴﺔ
][24
ﺍﻟﻁﻴﻥ ﺍﻟﻘﺎﺴﻲ
ﺍﻟﻘﺸﺭﺓ ﺍﻟﻌﻠﻴﺎ
ﺍﻟﻁﻴﻥ ﺍﻟﻠﻴﻥ
ﺍﻟﻤﺤﺘﻭﻯ ﺍﻟﻤﺎﺌﻲ )(%
40-15
78-40
31-25
ﺤﺩ ﺍﻟﺴﻴﻭﻟﺔ )% (LL
50-20
60-36
56-50
ﺤﺩ ﺍﻟﻠﺩﻭﻨﺔ )% (PL
40-16
30-18
33-25
ﻤﻌﻴﺎﺭ ﺍﻟﻠﺩﻭﻨﺔ )% (PI
20-5
32-20
30-24
2
1
24-9
60-20
45-12
< 50
12-7
5-3
60-15
0.42-0.37
0.88-0.40
0.31-0.17
ﺍﺨﺘﺒﺎﺭ ﺍﻻﺨﺘﺭﺍﻕ ﺍﻟﻘﻴﺎﺴـﻲ ) ،(SPTﻋـﺩﺩ ﺍﻟﻀﺭﺒﺎﺕ 300/ﻤﻡ ﻗﻭﺓ ﺍﻟﻘﺹ )ﺘﺠﺭﺒﺔ ﺍﻟﻤﺭﻭﺤﺔ ﻓـﻲ ﺍﻟﺤﻘـل( ﻜﻴﻠﻭﻨﻴﻭﺘﻥ/ﻡ
2
ﻤﻘﺎﻭﻤﺔ ﺍﻟﻤﺨﺭﻭﻁ )،(CPT ) (qcﻜﺠﻡ/ﺴﻡ
2
ﻤﻌﺎﻤل ﺍﻻﻨﻀﻐﺎﻁ )(Cc
ﺍﻟﺒﻨﻲ
ﻋﺒﺩﺍﷲ ﺒﻥ ﺇﺒﺭﺍﻫﻴﻡ ﺍﻟﻤﻬﻴﺩﺏ
68
ﻭﻟﺫﻟﻙ ﻴﻤﻜﻥ ﻤﻌﺎﻟﺠﺔ ﺘﺭﺒﺔ ﻫﺫﻩ ﺍﻟﻁﺒﻘﺔ ﺒﻭﺍﺴﻁﺔ ﻁﺭﻴﻘﺔ ﺍﻟﺘﺤﻤﻴل ﺍﻟﻤﺴﺒﻕ )ﺴﻭﻑ ﻴﺘﻡ ﺍﻟﺤﺩﻴﺙ ﻋﻨﻬﺎ ﻻﺤﻘ ﹰﺎ( ﺨﺎﺼﺔ ﺃﻥ ﺴﻤﻜﻬﺎ ﻗﻠﻴل .ﺃﻤﺎ ﻁﺒﻘﺔ ﺍﻟﻁﻴﻥ ﺍﻟﻘﺎﺴﻲ ﻓﺈﻥ ﻗﻴﻡ ﻗﻭﺓ ﺍﻟﻘﺹ ﻭﻜﺫﻟﻙ ﻤﻘﺎﻭﻤﺔ ﺍﻟﻤﺨﺭﻭﻁ ﻭﻋﺩﺩ ﺍﻟﻀﺭﺒﺎﺕ ﻻﺨﺘﺒﺎﺭ ﺍﻻﺨﺘﺭﺍﻕ ﺍﻟﻘﻴﺎﺴﻲ ﻋﺎﻟﻴﺔ ﻤﻤﺎ ﻴﺩل ﻋﻠﻰ ﻗﻭﺓ ﺘﺤﻤل ﺍﻟﺘﺭﺒﺔ ﻓﻲ ﻫﺫﻩ ﺍﻟﻁﺒﻘﺔ .ﻜﻤﺎ ﺘﺘﺼﻑ ﻫﺫﻩ ﺍﻟﻁﺒﻘﺔ ﺒﺎﻨﻀﻐﺎﻁﻴﺘﻬﺎ ﺍﻟﻤﻨﺨﻔﻀﺔ ﻭﻴﺘﻀﺢ ﺫﻟﻙ ﻤﻥ ﻗﻴﻡ ﻤﻌﺎﻤل ﺍﻻﻨﻀﻐﺎﻁ ﺍﻟﻤﻨﺨﻔﻀﺔ. ﻭﻴﺒﻴﻥ ﺠﺩﻭل ) (10ﺍﻟﻤﺤﺘﻭﻯ ﺍﻟﻜﻴﻤﻴﺎﺌﻲ ﻟﻤﻴﺎﻩ ﺍﻟﺴﺒﺨﺔ ﺍﻟﻁﻴﻨﻴﺔ ﺤﻴﺙ ﻴﺘﻀﺢ ﺘﺭﻜﻴﺯ ﺃﻤﻼﺡ ﺍﻟﻜﺒﺭﻴﺘﺎﺕ ﻭﺍﻟﻜﻠﻭﺭﻴﺩﺍﺕ ﺒﺸﻜل ﺨﺎﺹ ﻓﻲ ﻫﺫﻩ ﺍﻟﻤﻴﺎﻩ .ﻭﻟﺫﻟﻙ ﻓﺈﻨﻪ ﻴﺠﺏ ﺍﺴﺘﺨﺩﺍﻡ ﺍﻷﺴﻤﻨﺕ ﺍﻟﻤﻘﺎﻭﻡ ) (Type Vﻓﻲ ﺨﻠﻁﺎﺕ ﺨﺭﺴﺎﻨﺔ ﺍﻷﺴﺎﺴﺎﺕ،ﻭﻜﺫﻟﻙ ﻴﺠﺏ ﻁﻼﺀ ﺍﻷﺴﺎﺴﺎﺕ ﺒﻤﻭﺍﺩ ﻋﺎﺯﻟﺔ ﻤﺜل ﺍﻟﺒﻴﺘﻭﻤﻴﻥ ﻭﺫﻟﻙ ﻟﺤﻤﺎﻴﺔ ﺍﻟﺨﺭﺴﺎﻨﺔ ﻭﺍﻟﺤﺩﻴﺩ ﻤﻥ ﺍﻟﺘﺂﻜل. ﺠﺩﻭل ) : (10ﺍﻟﻤﺤﺘﻭﻯ ﺍﻟﻜﻴﻤﻴﺎﺌﻲ ﻟﻤﻴﺎﻩ ﺍﻟﺴﺒﺨﺔ ﺍﻟﻁﻴﻨﻴﺔ ﻓﻲ ﺃﺒﺤﺭ ﺍﻷﻴﻭﻨﺎﺕ
ﺍﻟﻘﻴﻤﺔ )ﺠﻡ/ﻟﺘﺭ(
ﺍﻟﺼﻭﺩﻴﻭﻡ )(Na+
95-20
ﺍﻟﻤﻐﻨﺴﻴﻭﻡ )(Mg++
3.33-1.83
ﺍﻟﺒﻭﺘﺎﺴﻴﻭﻡ )(K+
1.9-0.5
ﺍﻟﻜﺎﻟﺴﻴﻭﻡ )(Ca++
1.8-0.44
ﺍﻟﻜﻠﻭﺭﺍﻴﺩ )(Cl-
49.6-27.5
ﺍﻟﻜﺒﺭﻴﺘﺎﺕ (So4)--
4.35-3.21
ﺍﻟﺒﻴﻜﺭﺒﻭﻨﺎﺕ (HCO3)-
0.25-0.21
ﺍﻟﺭﻗﻡ ﺍﻟﻬﻴﺩﺭﻭﺠﻴﻨﻲ )(pH
7.6-7.05
ﺍﻟﻤﻠﻭﺤﺔ )(Salinity
155-50
][24
69
ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺍﻟﻤﻤﻠﻜﺔ ﺍﻟﻌﺭﺒﻴﺔ ﺍﻟﺴﻌﻭﺩﻴﺔ ....
4ـ 3ـ 3ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺍﻟﻠﻴﺙ : ﺘﻘﻊ ﻤﺩﻴﻨﺔ ﺍﻟﻠﻴﺙ ﻋﻠﻰ ﺒﻌﺩ 250ﻜﻠﻡ ﺠﻨﻭﺏ ﻤﺩﻴﻨﺔ ﺠﺩﺓ ،ﻭﻫﻲ ﺇﺤﺩﻯ ﺴﺒﺨﺎﺕ ﺍﻟﺴﺎﺤل ﺍﻟﻐﺭﺒﻲ ﻟﻠﻤﻤﻠﻜﺔ ﺍﻟﻌﺭﺒﻴﺔ ﺍﻟﺴﻌﻭﺩﻴﺔ .ﻭﺒﺩﺃﺕ ﻋﻤﻠﻴﺔ ﺘﻜﻭﻴﻥ ﻫﺫﻩ ﺍﻟﺴﺒﺨﺔ ﺒﻐﻤﺭ ﻤﻴﺎﻩ ﺍﻟﺒﺤﺭ ﺍﻷﺤﻤﺭ ﻟﻠﻤﻨﻁﻘﺔ ﺍﻟﺘﻲ ﻜﺎﻨﺕ ﻤﻜﻭﻨﺔ ﻤﻥ ﺍﻟﺭﻤﺎل ﺍﻟﻤﻨﻘﻭﻟﺔ ﺒﻭﺍﺴﻁﺔ ﺍﻟﺭﻴﺎﺡ ،ﻭﻨﺘﻴﺠﺔ ﻟﺫﻟﻙ ﻗﺎﻤﺕ ﻫﺫﻩ ﺍﻟﻤﻴﺎﻩ ﺒﺨﻠﻁ ﻫﺫﻩ ﺍﻟﺭﻤﺎل ﻤﻊ ﺍﻟﺘﺭﺴﺒﺎﺕ ﺍﻟﺒﺤﺭﻴﺔ ﻤﻤﺎ ﺃﺩﻯ ﺇﻟﻰ ﺘﻜﻭﻴﻥ ﺍﻟﻁﻤﻲ ﻭﺍﻟﻁﻴﻥ ،ﻭﻤﻥ ﺜﻡ ﺘﻜﻭﻨﺕ ﺴﻼﺴل ﺼﺨﺭﻴﺔ ﻤﻥ ﺍﻟﺤﺠﺭ ﺍﻟﺠﻴﺭﻱ ﻋﻤﻠﺕ ﻜﺤﺎﺠﺯ ﺒﻴﻥ ﻫﺫﻩ ﺍﻟﻤﻨﻁﻘﺔ ﻭﺒﻴﻥ ﻤﻴﺎﻩ ﺍﻟﺒﺤﺭ ﺍﻷﺤﻤﺭ .ﻭﻋﻨﺩ ﺍﻨﺤﺴﺎﺭ ﻭﺘﺭﺍﺠﻊ ﻤﻴﺎﻩ ﺍﻟﺒﺤﺭ ،ﺍﺯﺩﺍﺩﺕ ﻤﻌﺩﻻﺕ ﺍﻟﺘﺒﺨﺭ ﻤﻤﺎ ﺃﺩﻯ ﺇﻟﻰ ﺘﻜﻭﻴﻥ ﺘﺭﺴﺒﺎﺕ ﺍﻟﺴﺒﺨﺔ ﺍﻟﺤﺎﻟﻴﺔ ﺍﻟﻤﻜﻭﻨﺔ ﻟﺴﺒﺨﺔ ﺍﻟﻠﻴﺙ .ﻭﻴﻭﻀﺢ ﺸﻜل ) (18ﻤﻘﻁﻌﹰﺎ ﺠﺎﻨﺒﻴﹰﺎ ﻟﺴﺒﺨﺔ ﺍﻟﻠﻴﺙ ﻭﺫﻟﻙ ﺍﻤﺘﺩﺍﺩﺍ ﻤﻥ ﺍﻟﺒﺤﺭ ﺍﻷﺤﻤﺭ ﻭﺤﺘﻰ ﺍﻟﺩﺍﺨل].[26
ﻋﺒﺩﺍﷲ ﺒﻥ ﺇﺒﺭﺍﻫﻴﻡ ﺍﻟﻤﻬﻴﺩﺏ
70
ﻭﺘﺘﻜﻭﻥ ﺴﺒﺨﺔ ﺍﻟﻠﻴﺙ ﻤﻥ ﺜﻼﺜﺔ ﺃﻨﻭﺍﻉ ﻤﻥ ﺍﻟﺘﺭﺒﺔ ﻫﻲ :ﻁﻤﻲ ﻤﻨﺨﻔﺽ ﺍﻟﻠﺩﻭﻨﺔ، ﻭﻁﻤﻲ ﺭﻤﻠﻲ ،ﻭﻁﻴﻥ ﻤﻨﺨﻔﺽ ﺍﻟﻠﺩﻭﻨﺔ .ﻭﻴﻤﻜﻥ ﺘﺤﺩﻴﺩ ﻁﺒﻘﺎﺕ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺃﺭﺒﻊ ﻤﻨﺎﻁﻕ ﻋﻠﻰ ﺍﻟﻨﺤﻭ ﺍﻟﺘﺎﻟﻲ ]:[26 ﺍﻟﻤﻨﻁﻘﺔ ﺍﻷﻭﻟﻰ: ﻭﺘﻤﺘﺩ ﻫﺫﻩ ﺍﻟﻤﻨﻁﻘﺔ ﻤﻥ ﺍﻟﺴﻁﺢ ﺇﻟﻰ ﺃﺴﻔل ﻗﺎﻁﻌﺔ ﻤﻨﺴﻭﺏ ﺍﻟﻤﻴﺎﻩ ﺍﻟﺠﻭﻓﻴﺔ ﻭﻴﺘﺭﺍﻭﺡ ﺴﻤﻜﻬﺎ ﺒﻴﻥ 0.5ﻭ 2ﻤﺘﺭ .ﻭﺘﺸﻤل ﻫﺫﻩ ﺍﻟﻤﻨﻁﻘﺔ ﻗﺸﺭﺓ ﺍﻟﺴﺒﺨـﺔ ﻭﻁﺒﻘﺎﺕ ﺃﺨﺭﻯ ﻤﺘﺘﺎﻟﻴﺔ ﻤﻜﻭﻨﺔ ﻤﻥ ﺍﻟﻁﻤﻲ ﻭﺍﻟﻁﻴﻥ .ﻭﺍﻟﺘﺭﺒﺔ ﺍﻟﻤﻜﻭﻨﺔ ﻟﻬﺫﻩ ﺍﻟﻁﺒﻘﺎﺕ ﻤﺘﻤﺎﺴﻜﺔ ﺇﻟﻰ ﺸﺩﻴﺩﺓ ﺍﻟﺘﻤﺎﺴﻙ ﻋﻨﺩﻤﺎ ﺘﻜﻭﻥ ﺠﺎﻓﺔ ،ﻭﻟﻜﻨﻬﺎ ﺘﺼﺒﺢ ﻤﻔﻜﻜﺔ ﻋﻨﺩﻤﺎ ﻴﺘﺒﻠل ﺍﻟﺴﻁﺢ ﺒﻤﻴﺎﻩ ﺍﻷﻤﻁﺎﺭ ﺃﻭ ﺍﻟﻤﻴﺎﻩ ﺍﻟﺠﻭﻓﻴﺔ ﺍﻟﻤﺭﺘﻔﻌﺔ ﺍﻟﺘﻲ ﺘﺫﻴﺏ ﺍﻷﻤﻼﺡ ﺍﻟﺘﻲ ﺘﺭﺒﻁ ﺒﻴﻥ ﺤﺒﻴﺒﺎﺕ ﺍﻟﺘﺭﺒﺔ. ﺍﻟﻤﻨﻁﻘﺔ ﺍﻟﺜﺎﻨﻴﺔ: ﻭﺘﻤﺘﺩ ﻤﻥ ﻋﻤﻕ ﻤﺘﺭ ﺇﻟﻰ ﺃﺭﺒﻌﺔ ﺃﻤﺘﺎﺭ ﻭﺘﺤﻭﻱ ﻁﺒﻘﺎﺕ ﺭﻤﻠﻴﺔ ﻭﻁﺒﻘﺎﺕ ﻤﻜﻭﻨﺔ ﻤﻥ ﺍﻟﻁﻴﻥ ﻭﺍﻟﻁﻤﻲ ﻭﺒﻌﺽ ﺍﻟﺘﺭﺴﺒﺎﺕ ﺍﻟﺒﺤﺭﻴﺔ ،ﻭﻋﻤﻭﻤﹰﺎ ﺘﻜﻭﻥ ﺍﻟﺘﺭﺒﺔ ﻤﺘﻭﺴﻁﺔ ﺍﻟﺘﻤﺎﺴﻙ ﻓﻲ ﻫﺫﻩ ﺍﻟﻤﻨﻁﻘﺔ. ﺍﻟﻤﻨﻁﻘﺔ ﺍﻟﺜﺎﻟﺜﺔ: ﻭﺘﻤﺘﺩ ﻤﻥ ﻋﻤﻕ ﺜﻼﺜﺔ ﺇﻟﻰ ﺴﺘﺔ ﺃﻤﺘﺎﺭ ﻭﺘﺤﺘﻭﻱ ﻋﻠﻰ ﺍﻟﻁﻤﻲ ﺍﻟﻤﻨﺨﻔﺽ ﺍﻟﻠﺩﻭﻨﺔ ﻭﺍﻟﻁﻴﻥ ﺍﻟﻁﻤﻴﻲ .ﻭﺍﻟﺘﺭﺒﺔ ﻓﻲ ﻫﺫﻩ ﺍﻟﻤﻨﻁﻘﺔ ﺘﻜﻭﻥ ﻤﺘﻤﺎﺴﻜﺔ ﺇﻟﻰ ﺸﺩﻴﺩﺓ ﺍﻟﺘﻤﺎﺴﻙ. ﺍﻟﻤﻨﻁﻘﺔ ﺍﻟﺭﺍﺒﻌﺔ: ﻭﻫﻲ ﺍﻟﻤﻨﻁﻘﺔ ﺍﻟﺘﻲ ﺃﺴﻔل ﺍﻟﻤﻨﻁﻘﺔ ﺍﻟﺜﺎﻟﺜﺔ ﻭﺘﺘﻤﻴﺯ ﺒﻤﻘﺎﻭﻤﺘﻬﺎ ﺍﻟﻌﺎﻟﻴﺔ ﻟﻼﺨﺘﺭﺍﻕ. ﻭﺍﻟﺘﺭﺒﺔ ﺍﻟﻤﻜﻭﻨﺔ ﻟﻬﺫﻩ ﺍﻟﻁﺒﻘﺔ ﻋﺒﺎﺭﺓ ﻋﻥ ﻁﻴﻥ ﺸﺩﻴﺩ ﺍﻟﺘﻤﺎﺴﻙ ﺃﻭ ﺤﺠﺭ ﺠﻴﺭﻱ.
71
ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺍﻟﻤﻤﻠﻜﺔ ﺍﻟﻌﺭﺒﻴﺔ ﺍﻟﺴﻌﻭﺩﻴﺔ ....
ﻭﻴﻭﻀﺢ ﺠﺩﻭل ) (11ﺍﻟﺨﻭﺍﺹ ﺍﻟﺠﻴﻭﺘﻜﻨﻴﻜﻴﺔ ﻟﺴﺒﺨﺔ ﺍﻟﻠﻴﺙ ﺤﻴﺙ ﻴﺘﻀﺢ ﻤﻥ ﻗﻴﻡ ﻗﻭﺓ ﺍﻟﻘﺹ ﻭﺯﺍﻭﻴﺔ ﺍﻻﺤﺘﻜﺎﻙ ﻗﻭﺓ ﺘﺤﻤل ﺍﻟﺘﺭﺒﺔ ﻭﺃﻨﻬﺎ ﺫﺍﺕ ﺍﻨﻀﻐﺎﻁﻴﻪ ﻤﻨﺨﻔﻀﺔ ﻭﺫﻟﻙ ﻤﻥ ﻗﻴﻡ ﻤﻌﺎﻤل ﺍﻻﻨﻀﻐﺎﻁ ﺍﻟﻤﻨﺨﻔﻀﺔ ﻟﻜل ﻤﻥ ﺍﻟﻁﻴﻥ ﻭﺍﻟﻁﻤﻲ .ﻭﺒﻨﺎ ًﺀ ﻋﻠﻰ ﻫﺫﻩ ﺍﻟﺨﺼﺎﺌﺹ ﻓﺈﻨﻪ ﻴﻤﻜﻥ ﺍﻟﺒﻨﺎﺀ ﻓﻭﻕ ﻫﺫﻩ ﺍﻟﺘﺭﺒﺔ ﻤﺒﺎﺸﺭﺓ ﻭﺫﻟﻙ ﺒﺎﺴﺘﺨﺩﺍﻡ ﻗﻭﺍﻋﺩ ﻤﻨﻔﺼﻠﺔ ﻟﻠﻤﺒﺎﻨﻲ ﺫﺍﺕ ﺍﻷﺤﻤﺎل ﺍﻟﻌﺎﺩﻴﺔ.
5ـ ﺍﻟﻤﺸﺎﻜل ﺍﻟﻬﻨﺩﺴﻴﺔ ﺍﻟﻤﺼﺎﺤﺒﺔ ﻟﻭﺠﻭﺩ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﺇﻥ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﺘﺭﺒﺔ ﻏﻴﺭ ﻋﺎﺩﻴﺔ ،ﺫﺍﺕ ﺼﻔﺎﺕ ﻤﺘﻐﻴﺭﺓ ﻤﻥ ﺤﻴﺙ ﺃﺤﺠﺎﻡ ﻭﺃﺸﻜﺎل ﺤﺒﻴﺒﺎﺘﻬﺎ ،ﻭﻗﻭﺓ ﺍﻟﺘﺭﺍﺒﻁ ﻓﻴﻤﺎ ﺒﻴﻨﻬﺎ ،ﺤﻴﺙ ﻴﺅﺩﻱ ﺍﺨﺘﻼﻑ ﺍﻟﻤﻭﺍﺩ ﺍﻟﻤﻜﻭﻨﺔ ﻟﻠﺴﺒﺨﺔ ﻤﻥ ﻤﻜﺎﻥ ﺇﻟﻰ ﺁﺨﺭ ﺇﻟﻰ ﺍﺨﺘﻼﻑ ﺨﻭﺍﺼﻬﺎ ﺍﻟﺠﻴﻭﺘﻜﻨﻴﻜﻴﺔ ﻤﻤﺎ ﻴﻨﺘﺞ ﻋﻨﻪ ﻤﺸﺎﻜل ﻋﺩﻴﺩﺓ ﻟﻠﻤﺸﺎﺭﻴﻊ ﺍﻟﻬﻨﺩﺴﻴﺔ ﺍﻟﻤﻨﺸﺄﺓ ﻋﻠﻴﻬﺎ .ﻭﻤﻥ ﺃﻫﻡ ﻫﺫﻩ ﺍﻟﻤﺸﺎﻜل ﻤﺎ ﻴﻠﻲ ]: [1 ﺠﺩﻭل ) : (11ﺍﻟﺨﻭﺍﺹ ﺍﻟﺠﻴﻭﺘﻜﻨﻴﻜﻴﺔ ﻟﺴﺒﺨﺔ ﺍﻟﻠﻴﺙ
ﺍﻟﺨﺎﺼﻴﺔ ﺤﺩ ﺍﻟﺴﻴﻭﻟﺔ )% (LL ﺤﺩ ﺍﻟﻠﺩﻭﻨﺔ )% (PL ﻤﻌﻴﺎﺭ ﺍﻟﻠﺩﻭﻨﺔ )% (PI 2 ﺍﻟﺘﻤﺎﺴﻙ ،ﻜﺠﻡ/ﺴﻡ ﺯﺍﻭﻴﺔ ﺍﻻﺤﺘﻜﺎﻙ ﺍﻟﺩﺍﺨﻠﻲ φ ﻗﻭﺓ ﺍﻟﻘﺹ )ﻁﻥ/ﻡ(2 ﻤﻌﺎﻤل ﺍﻻﻨﻀﻐﺎﻁ )(Cc ﻤﻌﺎﻤل ﺍﻻﺭﺘﺩﺍﺩ )(Cs
][26
ﺍﻟﻁﻴﻥ ﺍﻟﻤﻨﺨﻔﺽ ﺍﻟﻠﺩﻭﻨﺔ ﺍﻟﻁﻤﻲ ﺍﻟﻤﻨﺨﻔﺽ ﺍﻟﻠﺩﻭﻨﺔ 48-15 40-22 35-0 16-15 13-0 24-7 0.05 0.41-0.052 40 33-22 12.8-2.20 22.8-2.20 0.14-0.038 0.186-0.05 0.063-0.016 0.065-0.016
ﻋﺒﺩﺍﷲ ﺒﻥ ﺇﺒﺭﺍﻫﻴﻡ ﺍﻟﻤﻬﻴﺩﺏ
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-1ﻴﺅﺩﻱ ﺘﺒﺎﻴﻥ ﻗﺎﺒﻠﻴﺔ ﺍﻨﻀﻐﺎﻁ ﻁﺒﻘﺎﺕ ﺍﻟﺴﺒﺨﺔ ﺨﺎﺼﺔ ﺍﻟﻐﻴﺭ ﻤﺘﻤﺎﺴﻜﺔ ﻤﻨﻬﺎ ﺇﻟﻰ ﺘﺒﺎﻴﻥ ﺇﻨﻀﻐﺎﻁ ﺍﻟﺘﺭﺒﺔ ﻷﻱ ﻤﻨﺸﺄ ﻫﻨﺩﺴﻲ ﻴﻘﺎﻡ ﻋﻠﻴﻬﺎ .ﻭﻴﺴﺒﺏ ﺍﻟﻬﺒﻭﻁ ﺍﻟﻤﺘﺒﺎﻴﻥ ﻟﻠﺘﺭﺒﺔ ﺍﻟﻌﺩﻴﺩ ﻤﻥ ﺍﻟﺘﺼﺩﻋﺎﺕ ﻭﺍﻟﺘﺸﻘﻘﺎﺕ ﻓﻲ ﺍﻟﻤﻨﺸﺂﺕ ،ﻭﻗﺩ ﺘﻡ ﺭﺼﺩ ﺍﻟﻌﺩﻴﺩ ﻤﻥ ][11 ﺍﻟﻤﻨﺸﺂﺕ ﺍﻟﺨﺭﺴﺎﻨﻴﺔ ﺍﻟﺘﻲ ﻅﻬﺭﺕ ﻓﻴﻬﺎ ﻫﺫﻩ ﺍﻟﺘﺼﺩﻋﺎﺕ ﻓﻲ ﻜل ﻤﻥ ﺠﻴﺯﺍﻥ ﻭﺍﻟﻤﻨﻁﻘﺔ ﺍﻟﺸﺭﻗﻴﺔ].[2 -2ﺇﻥ ﻗﻭﺓ ﺍﻟﻁﺒﻘﺔ ﺍﻟﻌﻠﻴﺎ )ﺍﻟﻘﺸﺭﺓ( ﻤﻥ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﺘﻨﻘﺹ ﻋﻨﺩ ﻤﻼﻤﺴﺘﻬﺎ ﻟﻠﻤﺎﺀ ﺃﻴﹰﺎ ﻜﺎﻥ ﻤﺼﺩﺭﻩ ﺴﻭﺍ ًﺀ ﺃﻜﺎﻥ ﻫﻁﻭل ﺍﻷﻤﻁﺎﺭ ،ﺃﻭ ﺍﻟﻤﺩ ﻭﺍﻟﺠﺯﺭ ﻭﻁﻭﻓﺎﻥ ﺍﻟﻤﻴﺎﻩ، ﺃﻭ ﺍﻤﺘﺼﺎﺹ ﺍﻟﺴﺒﺨﺔ ﻟﻠﺭﻁﻭﺒﺔ ﺍﻟﻌﺎﻟﻴﺔ ﺍﻟﻤﻭﺠﻭﺩﺓ ﻓﻲ ﺍﻟﺠﻭ .ﻭﻴﺅﺩﻱ ﻨﻘﺼﺎﻥ ﺍﻟﻘﻭﺓ ﺇﻟﻰ ﻋﺩﻡ ﺘﻤﻜﻥ ﺴﻁﺢ ﺍﻟﺴﺒﺨﺔ ﻤﻥ ﺤﻤل ﺃﻱ ﻭﺯﻥ ﻨﻅﺭﹰﺍ ﻻﻜﺘﺴﺎﺏ ﺍﻟﺴﺒﺨﺔ ﻗﻭﺓ ﺘﻤﺎﺴﻜﻬﺎ ﻤﻥ ﻭﺠﻭﺩ ﺍﻟﻤﻭﺍﺩ ﺍﻟﻜﻴﻤﻴﺎﺌﻴﺔ ﺍﻟﻼﺤﻤﺔ ﻤﺜل ﺃﻤﻼﺡ ﺍﻟﻜﺒﺭﻴﺘﺎﺕ، ﻭﺍﻟﻜﻠﻭﺭﻴﺩﺍﺕ ﻭﺍﻟﻜﺭﺒﻭﻨﺎﺕ ﺍﻟﺘﻲ ﺘﺫﻭﺏ ﺒﻭﺍﺴﻁﺔ ﺍﻟﻤﺎﺀ. -3ﺘﺅﺩﻱ ﻤﺤﺎﻭﻻﺕ ﻀﻐﻁ ﺍﻟﻁﺒﻘﺎﺕ ﺍﻟﻌﻠﻴﺎ ﻟﻠﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﺒﺎﻟﻁﺭﻕ ﺍﻻﻋﺘﻴﺎﺩﻴﺔ ـ ﻟﻐﺭﺽ ﺯﻴﺎﺩﺓ ﻗﻭﺓ ﺘﺤﻤﻠﻬﺎ ﻭﺘﻘﻠﻴل ﻗﺎﺒﻠﻴﺘﻬﺎ ﻟﻼﻨﻀﻐﺎﻁ ـ ﺇﻟﻰ ﺘﻜﺴﻴﺭ ﺍﻟﺭﻭﺍﺒﻁ ﺒﻴﻥ ﺠﺯﻴﺌﺎﺕ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺍﻟﻁﺒﻘﺎﺕ ﺍﻟﺴﻔﻠﻴﺔ ﻤﻤﺎ ﻴﻘﻠل ﻤﻥ ﻗﻭﺓ ﺘﺤﻤﻠﻬﺎ. -4ﻴﺅﺩﻱ ﺘﺒﺨﺭ ﺍﻟﻤﻴﺎﻩ ﻤﻥ ﺴﻁﺢ ﺍﻟﺴﺒﺨﺔ ﺇﻟﻰ ﺍﺭﺘﻔﺎﻉ ﻤﻨﺴﻭﺏ ﺍﻟﻤﻴﺎﻩ ﺍﻟﺠﻭﻓﻴﺔ ﻭﺒﺎﻟﺘﺎﻟﻲ ﺘﻜﻭّﻥ ﺍﻷﻤﻼﺡ ﻋﻠﻰ ﺴﻁﺢ ﺍﻟﺴﺒﺨﺔ ﺒﻌﺩ ﻋﻤﻠﻴﺔ ﺍﻟﺘﺒﺨﺭ ﻟﻠﻤﻴﺎﻩ .ﻭﻴﻤﻜﻥ ﺃﻥ ﻴﺘﺸﻘﻕ ﻫﺫﺍ ﺍﻟﺴﻁﺢ ﺍﻟﻤﺎﻟﺢ ﻋﻨﺩ ﺘﻌﺭﻀﻪ ﻟﺩﺭﺠﺎﺕ ﺤﺭﺍﺭﺓ ﻋﺎﻟﻴﺔ ﺨﺎﺼ ﹰﺔ ﻓﻲ ﻓﺼل ﺍﻟﺼﻴﻑ ،ﻭﺒﺎﻟﺘﺎﻟﻲ ﺤﺩﻭﺙ ﺍﻷﻀﺭﺍﺭ ﻟﻠﻤﻨﺸﺂﺕ ﺍﻟﻤﻘﺎﻤﺔ ﻋﻠﻴﻬﺎ ﺨﺎﺼﺔ ﺍﻟﻁﺭﻕ. -5ﻴﺅﺩﻱ ﺍﻟﺘﻐﻴﺭ ﺍﻟﺩﻭﺭﻱ ﻟﻤﺤﺘﻭﻯ ﺍﻟﺴﻭﺍﺌل ﻤﻥ ﺍﻷﻤﻼﺡ ﺍﻟﻤﺨﺘﻠﻔﺔ ﺍﻟﺘﺭﺍﻜﻴﺏ ﻨﺘﻴﺠﺔ ﻋﻤﻠﻴﺎﺕ ﺍﻟﺘﺭﺴﻴﺏ ﻭﺍﻟﺘﺒﺨﺭ ﺇﻟﻰ ﺤﺩﻭﺙ ﺍﻨﺘﻔﺎﺥ ﻭﺍﻨﻜﻤﺎﺵ ﻓﻲ ﻁﺒﻘﺎﺕ ﺍﻟﺘﺭﺒﺔ ،ﻤﻤﺎ ﻴﺅﺩﻱ ﺇﻟﻰ ﺯﻴﺎﺩﺓ ﺍﻟﻀﻐﻁ ﻋﻠﻰ ﺃﺴﺎﺴﺎﺕ ﺍﻟﻤﻨﺸﺂﺕ ﺍﻟﻤﻘﺎﻤﺔ ﻋﻠﻰ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﺘﺘﺸﻘﻕ ﻫﺫﻩ ﺍﻷﺴﺎﺴﺎﺕ ﻭﻗﺩ ﺘﻨﺘﻘل ﻫﺫﻩ ﺍﻟﺘﺸﻘﻘﺎﺕ ﺇﻟﻰ ﺍﻟﻤﻨﺸﺂﺕ ﻓﻭﻕ ﺴﻁﺢ ﺍﻟﺘﺭﺒﺔ. -6ﻴﺅﺜﺭ ﺍﻟﺘﺭﻜﻴﺯ ﺍﻟﻤﺭﺘﻔﻊ ﻷﻤﻼﺡ ﺍﻟﻜﻠﻭﺭﻴﺩﺍﺕ ﻓﻲ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ـ ﻭﺍﻟﺫﻱ ﻴﻤﺎﺜل ﺃﺭﺒﻌﺔ ﺇﻟﻰ ﺨﻤﺴﺔ ﺃﻀﻌﺎﻑ ﺃﻤﺜﺎﻟﻬﺎ ﻓﻲ ﻤﻴﺎﻩ ﺍﻟﺒﺤﺭ ـ ﻭﻜﺫﻟﻙ ﻭﺠﻭﺩ ﺍﻟﻜﺒﺭﻴﺘﺎﺕ
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ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺍﻟﻤﻤﻠﻜﺔ ﺍﻟﻌﺭﺒﻴﺔ ﺍﻟﺴﻌﻭﺩﻴﺔ ....
ﻓﻲ ﻤﻴﺎﻩ ﺍﻟﺴﺒﺨﺔ ﻋﻠﻰ ﻜل ﻤﻥ ﺍﻟﺨﺭﺴﺎﻨﺔ ﻭﺤﺩﻴﺩ ﺍﻟﺘﺴﻠﻴﺢ ﺤﻴﺙ ﺘﻌﻤل ﻋﻠﻰ ﺘﺂﻜل ﺃﺠﺯﺍﺀ ﺍﻟﺨﺭﺴﺎﻨﺔ ﻭﺤﺩﻴﺩ ﺍﻟﺘﺴﻠﻴﺢ.
6ـ ﻁﺭﻕ ﻤﻌﺎﻟﺠﺔ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﺇﻥ ﺤﺩﻭﺙ ﺍﻟﻤﺸﺎﻜل ﺍﻟﻤﺫﻜﻭﺭﺓ ﺁﻨﻔﹰﺎ ﻭﻏﻴﺭﻫﺎ ﻤﻥ ﺍﻷﻀﺭﺍﺭ ﻋﻨﺩ ﻭﺠﻭﺩ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﻤﻭﺍﻗﻊ ﺍﻟﻤﻨﺸﺂﺕ ﻴﺘﻁﻠﺏ ﺍﻟﻌﻤل ﻋﻠﻰ ﺇﻴﺠﺎﺩ ﺍﻟﺤﻠﻭل ﺍﻟﻤﻨﺎﺴﺒﺔ ﻟﺘﻔﺎﺩﻱ ﻫﺫﻩ ﺍﻟﻤﺸﺎﻜل ﺃﻭ ﺍﻟﺘﻘﻠﻴل ﻤﻥ ﺘﺄﺜﻴﺭﻫﺎ ﻋﻠﻰ ﺍﻟﻤﻨﺸﺂﺕ .ﻭﻤﻥ ﺃﻫﻡ ﻫﺫﻩ ﺍﻟﺤﻠﻭل ﻤﺎ ﻴﻠﻲ : -1ﺇﻤﻜﺎﻨﻴﺔ ﺍﺴﺘﺒﺩﺍل ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﺒﺘﺭﺒﺔ ﺠﻴﺩﺓ ،ﺨﺎﺼﺔ ﻋﻨﺩﻤﺎ ﺘﻜﻭﻥ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻗﺭﻴﺒﺔ ﻤﻥ ﺴﻁﺢ ﺍﻷﺭﺽ ﻭﺫﺍﺕ ﺴﻤﻙ ﻗﻠﻴل ﻨﺴﺒﻴﹰﺎ ﺤﻴﺙ ﻴﻤﻜﻥ ﺍﺴﺘﺒﺩﺍﻟﻬﺎ ﺒﺘﺭﺒﺔ ﺃﻓﻀل ﻤﻨﻬﺎ ﻭﻴﺘﻡ ﺩﻤﻙ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺠﺩﻴﺩﺓ ﺠﻴﺩﹰﺍ .ﻭﻫﺫﻩ ﺍﻟﻁﺭﻴﻘﺔ ﺘﻜﻭﻥ ﻤﻨﺎﺴﺒﺔ ﻟﻠﻤﺒﺎﻨﻲ ﺫﺍﺕ ﺍﻷﺤﻤﺎل ﺍﻟﺼﻐﻴﺭﺓ ﻭﺍﻟﻤﻜﻭﻨﺔ ﻤﻥ ﺩﻭﺭ ﻭﺍﺤﺩ ﺃﻭ ﺩﻭﺭﻴﻥ .ﻜﻤﺎ ﺘﺘﻁﻠﺏ ﻫﺫﻩ ﺍﻟﻁﺭﻴﻘﺔ ﻤﻨﻊ ﻭﺼﻭل ﺍﻟﻤﺎﺀ ﺇﻟﻰ ﺍﻟﺘﺭﺒﺔ ﻭﻜﺫﻟﻙ ﻋﺯل ﺍﻟﺨﺭﺴﺎﻨﺔ ﺍﻟﻤﺴﻠﺤﺔ ﻭﺍﻟﺘﺄﻜﺩ ﻤﻥ ﻋﺩﻡ ﻭﺼﻭل ﺍﻟﻤﻴﺎﻩ ﺍﻟﺠﻭﻓﻴﺔ ﺇﻟﻴﻬﺎ. -2ﻤﺤﺎﻭﻟﺔ ﺯﻴﺎﺩﺓ ﻗﻭﺓ ﺘﺤﻤل ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻭﺘﻘﻠﻴل ﻗﺎﺒﻠﻴﺘﻬﺎ ﻟﻼﻨﻀﻐﺎﻁ ﺒﻭﺍﺴﻁﺔ ﻀﻐﻁ ﺍﻟﻁﺒﻘﺎﺕ ﺍﻟﻌﻠﻴﺎ ﺒﺎﻟﻁﺭﻕ ﺍﻟﻤﻴﻜﺎﻨﻴﻜﻴﺔ ﻤﺜل ﺍﻟﺩﻤﻙ،ﻭﻫﺫﻩ ﺍﻟﻁﺭﻴﻘﺔ ﻓﻌﺎﻟﺔ ﻓﻲ ﺍﻟﺴﺒﺨﺔ ﺍﻟﺭﻤﻠﻴﺔ ﺇﻻ ﺃﻥ ﻤﺎ ﻴﻌﻭﻕ ﻫﺫﻩ ﺍﻟﻁﺭﻴﻘﺔ ﻫﻭ ﻗﺭﺏ ﻤﺴﺘﻭﻯ ﺍﻟﻤﻴﺎﻩ ﺍﻟﺠﻭﻓﻴﺔ ﻤﻥ ﺍﻟﺴﻁﺢ .ﻜﻤﺎ ﺃﻥ ﺍﻟﺩﻤﻙ ﻗﺩ ﻴﺅﺩﻱ ﺇﻟﻰ ﺘﻜﺴﻴﺭ ﺍﻟﺭﻭﺍﺒﻁ ﺒﻴﻥ ﺠﺯﻴﺌﺎﺕ ﺍﻟﺴﺒﺨﺔ ﺍﻟﻤﻭﺠﻭﺩﺓ ﻓﻭﻕ ﻤﺴﺘﻭﻯ ﺍﻟﻤﻴﺎﻩ ﺍﻟﺠﻭﻓﻴﺔ ﻤﻤﺎ ﻴﻘﻠل ﻤﻥ ﻗﻭﺓ ﺘﺤﻤﻠﻬﺎ. -3ﺍﻟﺘﺤﻤﻴل ﺍﻟﻤﺴﺒﻕ ) (Preloadingﻭﺫﻟﻙ ﺒﺘﺤﻤﻴل ﺍﻟﺘﺭﺒﺔ ﺒﺎﻟﺭﺩﻡ ﻭﺍﻟﺴﻤﺎﺡ ﻟﻬﺎ ﺒﺎﻟﻬﺒﻭﻁ ﻗﺒل ﺒﺩﺀ ﺍﻹﻨﺸﺎﺀ ،ﻭﻫﺫﻩ ﺍﻟﻁﺭﻴﻘﺔ ﻓﻌﺎﻟﺔ ﻓﻲ ﺍﻟﺴﺒﺨﺔ ﺍﻟﻁﻴﻨﻴﺔ .ﻭﻤﻥ ﻼ ﻗﺩ ﻴﺼل ﺇﻟﻰ ﻋﺩﺓ ﺸﻬﻭﺭ. ﻋﻴﻭﺏ ﻫﺫﻩ ﺍﻟﻁﺭﻴﻘﺔ ﺃﻨﻬﺎ ﺘﺴﺘﻐﺭﻕ ﻭﻗﺘﹰﺎ ﻁﻭﻴ ﹰ -4ﺘﺜﺒﻴﺕ ﺍﻟﺘﺭﺒﺔ ﻜﻴﻤﻴﺎﺌﻴﹰﺎ ﻭﺫﻟﻙ ﺒﺈﻀﺎﻓﺔ ﺍﻷﺴﻤﻨﺕ ﺃﻭ ﺍﻟﺠﻴﺭ ﻟﻬﺎ ﻟﻐﺭﺽ ﺘﺤﺴﻴﻥ ﺨﻭﺍﺼﻬﺎ ﺍﻟﺠﻴﻭﺘﻜﻨﻴﻜﻴﺔ .ﻭﺘﻌﺘﺒﺭ ﻫﺫﻩ ﺍﻟﻁﺭﻴﻘﺔ ﺭﺨﻴﺼﺔ ﺍﻟﺘﻜﺎﻟﻴﻑ ﻤﻘﺎﺭﻨﺔ ﺒﺎﻟﻁﺭﻕ ﺍﻷﺨﺭﻯ.
ﻋﺒﺩﺍﷲ ﺒﻥ ﺇﺒﺭﺍﻫﻴﻡ ﺍﻟﻤﻬﻴﺩﺏ
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-5ﺍﺴﺘﺨﺩﺍﻡ ﺍﻻﻨﺴﺠﺔ ﺍﻟﺼﻨﺎﻋﻴﺔ ) (Geotextilesﻟﺘﺤﺴﻴﻥ ﺨﻭﺍﺹ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻭﺯﻴﺎﺩﺓ ﻗﻭﺓ ﺘﺤﻤﻠﻬﺎ. ﻭﺴﻴﺘﻡ ﺍﺴﺘﻌﺭﺍﺽ ﺃﻫﻡ ﺍﻟﻁﺭﻕ ﺍﻟﺘﻲ ﺘﻡ ﺍﺴﺘﺨﺩﺍﻤﻬﺎ ﻟﻤﻌﺎﻟﺠﺔ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﻤﻨﺎﻁﻕ ﻭﺠﻭﺩﻫﺎ ﻓﻲ ﺍﻟﻤﻤﻠﻜﺔ ﻭﺫﻟﻙ ﻭﻓﻘﹰﺎ ﻟﻤﺎ ﺘﻀﻤﻨﺘﻪ ﺍﻟﺩﺭﺍﺴﺎﺕ ﺍﻟﺘﻲ ﺘﻡ ﻋﻤﻠﻬﺎ ﻤﻥ ﻗﺒل ﺍﻟﺒﺎﺤﺜﻴﻥ ﻓﻲ ﻜل ﻤﻨﻁﻘﺔ. 6ـ 1ﺘﺜﺒﻴﺕ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻜﻴﻤﻴﺎﺌﻴ ﹰﺎ : Chemical Stabilization ﻴﻤﻜﻥ ﺘﺜﺒﻴﺕ ﺍﻟﺘﺭﺒﺔ ﻜﻴﻤﻴﺎﺌﻴﹰﺎ ﺨﺎﺼﺔ ﻋﻨﺩﻤﺎ ﻴﺭﺍﺩ ﺍﺴﺘﺨﺩﺍﻤﻬﺎ ﻜﻤﺎﺩﺓ ﺭﺩﻡ ﻓﻲ ﻤﺸﺎﺭﻴﻊ ﺍﻟﻁﺭﻕ ﻭﻏﻴﺭﻫﺎ ﺤﻴﺙ ﺘﻌﻤل ﺍﻟﻤﺜﺒﺘﺎﺕ ﺍﻟﻜﻴﻤﻴﺎﺌﻴﺔ ﻤﺜل ﺍﻟﺠﻴﺭ ﺃﻭ ﺍﻷﺴﻤﻨﺕ ﺃﻭ ﺍﻷﺴﻔﻠﺕ ﻋﻠﻰ ﺯﻴﺎﺩﺓ ﻗﻭﺓ ﺘﺤﻤل ﺍﻟﺘﺭﺒﺔ .ﻜﻤﺎ ﺘﻌﻤل ﻫﺫﻩ ﺍﻟﻤﺜﺒﺘﺎﺕ ﻋﻠﻰ ﺘﻘﻠﻴل ﻤﻘﺩﺍﺭ ﺍﻻﻨﺘﻔﺎﺥ ﻭﺍﻻﻨﻜﻤﺎﺵ ﻟﻠﺘﺭﺒﺔ ﺒﺸﻜل ﻋﺎﻡ .ﻭﻟﻜﻥ ﻋﻨﺩ ﺍﺴﺘﺨﺩﺍﻡ ﻫﺫﻩ ﺍﻟﻁﺭﻕ ﻓﻲ ﺘﺜﺒﻴﺕ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ،ﻓﺈﻥ ﺍﻷﻤﺭ ﻴﺨﺘﻠﻑ ،ﺤﻴﺙ ﺘﻌﺘﺒﺭ ﺍﻟﺴﺒﺨﺔ ﺘﺭﺒﺔ ﻏﻴﺭ ﻋﺎﺩﻴﺔ ﻭﺫﻟﻙ ﻻﺤﺘﻭﺍﺌﻬﺎ ﻋﻠﻰ ﺍﻟﻌﺩﻴﺩ ﻤﻥ ﺍﻷﻤﻼﺡ ﻤﺜل ﺍﻟﻬﺎﻻﻴﺕ ،ﻭﺍﻟﺠﺒﺱ ،ﻭﺍﻟﻜﺎﻟﺴﺎﻴﺕ ،ﻭﻏﻴﺭﻫﺎ ﻭﺍﻟﺘﻲ ﹸﺘﺅﺜﺭ ﻓﻲ ﻤﺩﻯ ﺍﺴﺘﺠﺎﺒﺔ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻟﻠﻤﺜﺒﺘﺎﺕ ﺍﻟﻜﻴﻤﻴﺎﺌﻴﺔ .ﻭﺴﻴﺘﻡ ﺍﺴﺘﻌﺭﺍﺽ ﻨﺘﺎﺌﺞ ﺘﺜﺒﻴﺕ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺍﻟﻤﻨﻁﻘﺔ ﺍﻟﺸﺭﻗﻴﺔ ﻤﻥ ﺍﻟﻤﻤﻠﻜﺔ ﻜﻴﻤﻴﺎﺌﻴﹰﺎ ﻭﻤﺩﻯ ﻤﻨﺎﺴﺒﺔ ﻫﺫﻩ ﺍﻟﻁﺭﻴﻘﺔ ﻟﺘﺜﺒﻴﺕ ﺍﻟﺴﺒﺨﺔ. ﻟﻘﺩ ﺘﻤﺕ ﺩﺭﺍﺴﺔ ﺘﺜﺒﻴﺕ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﻜل ﻤﻥ ﺍﻟﺭﻴﺎﺱ ،ﻭﺍﻟﻘﺭﻴﺔ ،ﻭﺍﻟﻌﺯﻴﺯﻴﺔ ﻓﻲ ﺍﻟﻤﻨﻁﻘﺔ ﺍﻟﺸﺭﻗﻴﺔ ﻭﺫﻟﻙ ﺒﺈﻀﺎﻓﺔ ﻨﺴﺏ %3ﻭ %5ﻭ %7ﻭ %10ﻤﻥ ﻜل ﻤﻥ ﺍﻟﺠﻴﺭ ﻭﻤﻥ ﺍﻷﺴﻤﻨﺕ ﻟﻠﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﻫﺫﻩ ﺍﻟﻤﻨﺎﻁﻕ ﻭﻤﺩﻯ ﺘﺄﺜﻴﺭ ﺫﻟﻙ ﻋﻠﻰ ﺨﻭﺍﺹ ﺍﻟﺩﻤﻙ ،ﻭﻗﻴﻡ ﻨﺴﺒﺔ ﺍﻟﺘﺤﻤل ﺒﻤﻘﻴﺎﺱ ﻜﺎﻟﻴﻔﻭﺭﻨﻴﺎ ) ،(CBRﻭﻗﻴﻡ ﻤﻘﺎﻭﻤﺔ ﺍﻟﻀﻐﻁ ﻏﻴﺭ ﺍﻟﻤﺤﺼﻭﺭ ) (Unconfined Compressive Strengthﻟﻠﺘﺭﺒﺔ ] .[2ﻭﻗﺩ ﺘﻤﺕ ﺍﻟﺩﺭﺍﺴﺔ ﻋﻠﻰ ﺜﻼﺙ ﻋﻴﻨﺎﺕ ﻤﺨﺘﻠﻔﺔ ﺍﻟﺨﻭﺍﺹ ‘ﺃﺨﺫﺕ ﻤﻥ ﻜل ﺴﺒﺨﺔ ﺤﻴﺙ ﻜﺎﻥ ﺘﺼﻨﻴﻔﻬـﺎ ﻁﺒﻘﹰﺎ ﻟﻨﻅﺎﻡ ﺁﺸﺘﻭ ﻫﻭ ) ( A - 6ﻟﺴﺒﺨﺔ ﺍﻟﺭﻴﺎﺱ ﻭ ) ( A - 2 - 4ﻟﺴﺒﺨﺔ ﺍﻟﻘﺭﻴﺔ ﻭ ) ( A - 3ﻟﺴﺒﺨﺔ ﺍﻟﻌﺯﻴﺯﻴﺔ].[2
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ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺍﻟﻤﻤﻠﻜﺔ ﺍﻟﻌﺭﺒﻴﺔ ﺍﻟﺴﻌﻭﺩﻴﺔ ....
ﻭﻗﺩ ﺒﻴﻨﺕ ﻨﺘﺎﺌﺞ ﺍﻟﺩﺭﺍﺴﺔ ﻋﺩﻡ ﻭﺠﻭﺩ ﻋﻼﻗﺔ ﻭﺍﻀﺤﺔ ﺘﺭﺒﻁ ﺒﻴﻥ ﺍﻟﻤﺜﺒﺘﺎﺕ ﺍﻟﻜﻴﻤﻴﺎﺌﻴﺔ )ﺍﻟﺠﻴﺭ ﻭﺍﻷﺴﻤﻨﺕ( ﻭﺒﻴﻥ ﺨﻭﺍﺹ ﺍﻟﺩﻤﻙ ﺍﻟﻤﺘﻤﺜﻠﺔ ﻓﻲ ﺃﻜﺒﺭ ﻜﺜﺎﻓﺔ ﺠﺎﻓﺔ ﻭﺍﻟﺭﻁﻭﺒﺔ ﺍﻟﻤﺜﻠﻰ ﺍﻟﻤﺤﺘﻭﺍﺓ ﻟﻠﺴﺒﺨﺔ ﻓﻲ ﻫﺫﻩ ﺍﻟﻤﻨﺎﻁﻕ .ﺤﻴﺙ ﺃﺩﺕ ﺇﻀﺎﻓﺔ ﻨﺴﺒﺔ %3 ﺇﻟﻰ %10ﻤﻥ ﺍﻟﺠﻴﺭ ﺇﻟﻰ ﻨﻘﺼﺎﻥ ﺍﻟﻜﺜﺎﻓﺔ ﺍﻟﺠﺎﻓﺔ ﻭﺯﻴﺎﺩﺓ ﺍﻟﺭﻁﻭﺒﺔ ﺍﻟﻤﺜﻠﻰ ﺍﻟﻤﺤﺘﻭﺍﺓ، ﻋﻠﻤﹰﺎ ﺒﺄﻥ ﻤﻘﺩﺍﺭ ﻫﺫﻩ ﺍﻟﺯﻴﺎﺩﺓ ﺃﻭ ﺍﻟﻨﻘﺼﺎﻥ ﻜﺎﻥ ﺼﻐﻴﺭﹰﺍ .ﻭﻟﻡ ﻴﺘﻀﺢ ﺘﺄﺜﻴﺭ ﺇﻀﺎﻓﺔ ﻫﺫﻩ ﺍﻟﻨﺴﺏ ) % 3ـ (%10ﻤﻥ ﺍﻷﺴﻤﻨﺕ ﻋﻠﻰ ﺨﻭﺍﺹ ﺍﻟﺩﻤﻙ ﻟﻠﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﻫﺫﻩ ﺍﻟﻤﻨﺎﻁﻕ .ﻭﻟﻜﻥ ﻴﻤﻜﻥ ﺍﻟﻘﻭل ﺒﺄﻥ ﻜﺜﺎﻓﺔ ﺨﻠﻴﻁ ﺍﻟﺘﺭﺒﺔ ﻤﻊ ﺍﻷﺴﻤﻨﺕ ﺃﻋﻠﻰ ﻤﻥ ﻜﺜﺎﻓﺔ ﺨﻠﻴﻁ ﺍﻟﺘﺭﺒﺔ ﻤﻊ ﺍﻟﺠﻴﺭ ﻭﺫﻟﻙ ﻷﻥ ﺍﻟﻭﺯﻥ ﺍﻟﻨﻭﻋﻲ ﻟﻸﺴﻤﻨﺕ ﺃﻋﻠﻰ ﻤﻥ ﺍﻟﻭﺯﻥ ﺍﻟﻨﻭﻋﻲ ﻟﻠﺠﻴﺭ ].[2 ﻭﻴﺒﻴﻥ ﺠﺩﻭل ) (12ﻨﺴﺒﺔ ﺍﻟﺘﺤﺴﻥ ـ ﺍﻟﺘﻲ ﺘﻡ ﺤﺴﺎﺒﻬﺎ ﻤﻥ ﻗﺒل ﺍﻟﻤﺅﻟﻑ ﻤﻥ ﻨﺘﺎﺌﺞ ﻫﺫﻩ ﺍﻟﺩﺭﺍﺴﺔ ـ ﻓﻲ ﻗﻴﻡ ﻨﺴﺒﺔ ﺘﺤﻤل ﻜﺎﻟﻴﻔﻭﺭﻨﻴﺎ CBRﻭﻗﻴﻡ ﻤﻘﺎﻭﻤﺔ ﺍﻟﻀﻐﻁ ﻏﻴﺭ ﺍﻟﻤﺤﺼﻭﺭ ﻟﻠﺘﺭﺒﺔ ﺍﻟﻤﻌﺎﻟﺠﺔ ﺒﻨﺴﺏ %3ﺇﻟﻰ %10ﻤﻥ ﺍﻷﺴﻤﻨﺕ ﻓﻲ ﺍﻟﺴﺒﺨﺎﺕ ﺍﻟﺜﻼﺙ .ﻋﻠﻤﹰﺎ ﺒﺄﻥ ﺍﺨﺘﺒﺎﺭ ﻤﻘﺎﻭﻤﺔ ﺍﻟﻀﻐﻁ ﻏﻴﺭ ﺍﻟﻤﺤﺼﻭﺭ ﻗﺩ ‘ﺃﺠﺭﻱ ﻋﻠﻰ ﻨﻭﻋﻴﻥ ﻤﻥ ﺍﻟﻌﻴﻨﺎﺕ :ﻋﻴﻨﺎﺕ ﻤﻜﺸﻭﻓﺔ )ﻤﻌﺭﻀﺔ ﻟﻠﻤﺤﻴﻁ ﺍﻟﺨﺎﺭﺠﻲ (Exposed ﻭﻋﻴﻨﺎﺕ ﻤﻌﺯﻭﻟﺔ ﻋﻥ ﺍﻟﻤﺤﻴﻁ ﺍﻟﺨﺎﺭﺠﻲ ) .(Sealedﻭﻗﺩ ﺘﻡ ﺘﺤﻀﻴﺭ ﻫﺫﻩ ﺍﻟﻌﻴﻨﺎﺕ ﻓﻲ ﺍﻟﻤﻌﻤل ﺜﻡ ﺘﺭﻜﺕ ﻟﻤﺩﺓ 7ﺃﻴﺎﻡ ﻭﺒﻌﺩ ﺫﻟﻙ ﺃﺠﺭﻱ ﻋﻠﻴﻬﺎ ﺍﻻﺨﺘﺒﺎﺭ].[2 ﻭﻴﺘﻀﺢ ﻤﻥ ﺠﺩﻭل ) (12ﺃﻨﻪ ﻋﻨﺩ ﺇﻀﺎﻓﺔ %10ﻤﻥ ﺍﻷﺴﻤﻨﺕ ﻟﻠﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ، ﻓﺈﻥ ﻗﻴﻤﺔ ﻨﺴﺒﺔ ﺘﺤﻤل ﻜﺎﻟﻴﻔﻭﺭﻨﻴﺎ CBRﺘﺯﺩﺍﺩ ﺇﻟﻰ ﺤﻭﺍﻟﻲ ﺍﻟﻀﻌﻑ ) (%89ﻟﺴﺒﺨﺔ ﺍﻟﺭﻴﺎﺱ ،ﻜﻤﺎ ﺘﺯﺩﺍﺩ ﺇﻟﻰ ﺤﻭﺍﻟﻲ ﺜﻼﺜﺔ ﺇﻟﻰ ﺃﺭﺒﻌﺔ ﺃﻀﻌﺎﻑ ﻗﻴﻤﺘﻬﺎ ﻟﺴﺒﺨﺘﻲ ﺍﻟﻌﺯﻴﺯﻴﺔ ﻭﺍﻟﻘﺭﻴﺔ ) %353ﻭ .(%417ﻜﻤﺎ ﺃﻥ ﻨﺴﺏ ﺍﻟﺘﺤﺴﻥ ﻓﻲ ﻗﻴﻡ ﻤﻘﺎﻭﻤﺔ ﺍﻟﻀﻐﻁ ﻏﻴﺭ ﺍﻟﻤﺤﺼﻭﺭ ﻟﻠﻌﻴﻨﺎﺕ ﺍﻟﻤﻌﺯﻭﻟﺔ ﻟﻠﺴﺒﺨﺎﺕ ﺍﻟﺜﻼﺙ ﻜﺎﻨﺕ ﻗﺭﻴﺒﺔ ﻤﻥ ﻫﺫﻩ ﺍﻟﻨﺴﺏ ،ﻭﻜﺫﻟﻙ ﺍﻟﺤﺎل ﺒﺎﻟﻨﺴﺒﺔ ﻟﻠﻌﻴﻨﺎﺕ ﺍﻟﻤﻜﺸﻭﻓﺔ ﺒﺎﺴﺘﺜﻨﺎﺀ ﺴﺒﺨﺔ ﺍﻟﻘﺭﻴﺔ ﻭﺍﻟﺘﻲ ﺒﻠﻐﺕ ﻨﺴﺒﺔ ﺍﻟﺘﺤﺴﻥ ﻓﻴﻬﺎ ) %102ﺤﻭﺍﻟﻲ ﻀﻌﻑ ﺍﻟﻘﻴﻤﺔ( .ﻭﻤﻥ ﺫﻟﻙ ﻴﺘﻀﺢ ﺃﻥ ﻨﺴﺒﺔ ﺍﻟﺘﺤﺴﻥ ﺘﺨﺘﻠﻑ ﺤﺴﺏ ﻨﻭﻉ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻭﻴﺭﺠﻊ ﺍﻟﺴﺒﺏ ﻓﻲ ﺫﻟﻙ ﺇﻟﻰ ﺨﻭﺍﺹ ﺍﻟﻌﻴﻨﺎﺕ ﺍﻟﺜﻼﺙ
ﻋﺒﺩﺍﷲ ﺒﻥ ﺇﺒﺭﺍﻫﻴﻡ ﺍﻟﻤﻬﻴﺩﺏ
76
ﺍﻟﻤﺨﺘﻠﻔﺔ ﺤﻴﺙ ﺃﻥ ﻋﻴﻨﺔ ﺴﺒﺨﺔ ﺍﻟﺭﻴﺎﺱ ﻁﻴﻨﻴﺔ ﺘﺤﺘﻭﻱ ﻋﻠﻰ ﻨﺴﺒﺔ ﻜﺒﻴﺭﺓ ﻤﻥ ﺍﻟﻜﺒﺭﻴﺘﺎﺕ ﻭﻟﺫﻟﻙ ﻟﻡ ﺘﺴﺘﺠﺏ ﻟﻸﺴﻤﻨﺕ ﺒﻴﻨﻤﺎ ﺍﺴﺘﺠﺎﺒﺕ ﻋﻴﻨﺘﺎ ﺴﺒﺨﺘﻲ ﺍﻟﻌﺯﻴﺯﻴﺔ ﻭﺍﻟﻘﺭﻴﺔ ﻟﻪ ﻭﺫﻟﻙ ﻟﻁﺒﻴﻌﺘﻬﻤﺎ ﺍﻟﺭﻤﻠﻴﺔ ﻭﻷﻥ ﻨﺴﺒﺔ ﺍﻟﻜﺒﺭﻴﺘﺎﺕ ﻓﻴﻬﻤﺎ ﻟﻴﺴﺕ ﻋﺎﻟﻴﺔ ].[2 ﺠﺩﻭل ) : (12ﺍﻟﻨﺴﺒﺔ ﺍﻟﻤﺌﻭﻴﺔ ) (%ﻟﻤﻘﺩﺍﺭ ﺍﻟﺘﺤﺴﻥ ﻓﻲ ﻗﻴﻡ ﻨﺴﺒﺔ ﺘﺤﻤل ﻜﺎﻟﻴﻔﻭﺭﻨﻴﺎ ﻭﻗﻴﻡ ﻤﻘﺎﻭﻤﺔ ﺍﻟﻀﻐﻁ ﻏﻴﺭ ﺍﻟﻤﺤﺼﻭﺭ ﻟﻠﺘﺭﺒﺔ ﺍﻟﻤﻌﺎﻟﺠﺔ ﺒﺎﻷﺴﻤﻨﺕ ﻓﻲ ﺍﻟﻤﻨﻁﻘﺔ ﺍﻟﺸﺭﻗﻴﺔ
CBR
ﻨﺴﺒﺔ
ﻨﺴﺒﺔ ﺘﺤﻤل ﻜﺎﻟﻴﻔﻭﺭﻨﻴﺎ CBR
ﺍﻷﺴﻤﻨﺕ
ﺴﺒﺨﺔ
3 5 7 10
ﺍﻟﻘﺭﻴﺔ 107 184 336 417
ﺴﺒﺨﺔ
ﻤﻘﺎﻭﻤﺔ ﺍﻟﻀﻐﻁ ﻏﻴﺭ
ﺍﻟﻤﺤﺼﻭﺭ )ﻋﻴﻨﺎﺕ ﻤﻜﺸﻭﻓﺔ(
ﺴﺒﺨﺔ
ﺴﺒﺨﺔ
ﺍﻟﻌﺯﻴﺯﻴﺔ ﺍﻟﺭﻴﺎﺱ 47 61 41 182 78 228 89 353
ﺍﻟﻘﺭﻴﺔ 51 67 93 102
ﺴﺒﺨﺔ
ﺴﺒﺨﺔ
ﻤﻘﺎﻭﻤﺔ ﺍﻟﻀﻐﻁ ﻏﻴﺭ
ﺍﻟﻤﺤﺼﻭﺭ )ﻋﻴﻨﺎﺕ ﻤﻌﺯﻭﻟﺔ( ﺴﺒﺨﺔ
ﺍﻟﻌﺯﻴﺯﻴﺔ ﺍﻟﺭﻴﺎﺱ ﺍﻟﻘﺭﻴﺔ 144 53 114 279 51 202 331 75 303 451 128 380
ﺴﺒﺨﺔ
ﺴﺒﺨﺔ
ﺍﻟﻌﺯﻴﺯﻴﺔ 41 108 454 476
ﺍﻟﺭﻴﺎﺱ 31 35 69 98
ﻨﺴﺒﺔ ﺍﻟﺘﺤﺴﻥ ))] = (%ﺍﻟﻘﻴﻤﺔ ﺒﻌﺩ ﺍﻟﻤﻌﺎﻟﺠﺔ -ﺍﻟﻘﻴﻤﺔ ﻗﺒل ﺍﻟﻤﻌﺎﻟﺠﺔ( /ﺍﻟﻘﻴﻤﺔ ﻗﺒل ﺍﻟﻤﻌﺎﻟﺠﺔ [ 100 x
ﻭﻤﻥ ﻨﺘﺎﺌﺞ ﻫﺫﻩ ﺍﻟﺩﺭﺍﺴﺔ ﻴﺴﺘﺨﻠﺹ ﺃﻥ ﺘﺤﺴﻴﻥ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﺒﺈﻀﺎﻓﺔ ﺍﻟﺠﻴﺭ ﺇﻟﻴﻬﺎ ﻟﻡ ﻴﺤﺴﻥ ﺨﻭﺍﺼﻬﺎ ﺍﻟﺠﻴﻭﺘﻜﻨﻴﻜﻴﺔ ﺒﺸﻜل ﻋﺎﻡ ،ﺒﻴﻨﻤﺎ ﺴﺎﻋﺩﺕ ﺇﻀﺎﻓﺔ ﺍﻷﺴﻤﻨﺕ ﻋﻠﻰ ﺘﺤﺴﻴﻥ ﺨﻭﺍﺹ ﺃﻏﻠﺏ ﺃﻨﻭﺍﻉ ﺍﻟﺴﺒﺨﺔ ﺇﻻ ﺃﻥ ﺫﻟﻙ ﻴﺘﻁﻠﺏ ﺍﺴﺘﺨﺩﺍﻡ ﻨﺴﺒﺔ ﻋﺎﻟﻴﺔ ﻤﻥ ﺍﻷﺴﻤﻨﺕ ﺘﺼل ﺇﻟﻰ .%10 6ـ 2ﺘﺜﺒﻴﺕ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﺒﺎﺴﺘﺨﺩﺍﻡ ﺍﻟﺘﺤﻤﻴل ﺍﻟﻤﺴﺒﻕ :Preloading ﺘﺴﺘﺨﺩﻡ ﻁﺭﻴﻘﺔ ﺍﻟﺘﺤﻤﻴل ﺍﻟﻤﺴﺒﻕ ﻟﺘﻘﻠﻴل ﺍﻟﻬﺒﻭﻁ ﻟﻠﺘﺭﺒﺔ ﻋﻨﺩ ﺘﺤﻤﻴﻠﻬﺎ ﺒﺄﻭﺯﺍﻥ ﺍﻟﻤﻨﺸﺂﺕ ﺍﻟﻤﻘﺎﻤﺔ ﻋﻠﻴﻬﺎ .ﻭﺘﻌﺘﻤﺩ ﻫﺫﻩ ﺍﻟﻁﺭﻴﻘﺔ ﻋﻠﻰ ﺘﺤﻤﻴل ﺍﻟﺴﺒﺨﺔ ﺍﻟﻁﻴﻨﻴﺔ ﺒﺄﺤﻤﺎل ﻤﻥ ﺍﻟﺭﺩﻡ ﻭﺍﻟﺘﻲ ﺘﺘﻜﻭﻥ ﻏﺎﻟﺒﹰﺎ ﻤﻥ ﺍﻟﺭﻤل ﻟﻤﺩﺓ ﻤﻌﻴﻨﺔ ﻭﻤﺭﺍﻗﺒﺔ ﻤﻘﺩﺍﺭ ﺍﻟﻬﺒﻭﻁ ﻭﺒﺎﻟﺘﺎﻟﻲ ﺘﻘﻠﻴل ﻤﻘﺩﺍﺭ ﺍﻹﻨﻀﻐﺎﻁ ﺍﻟﺤﻘﻴﻘﻲ ﺒﻌﺩ ﺘﺤﻤﻴل ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﺒﻭﺍﺴﻁﺔ
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ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺍﻟﻤﻤﻠﻜﺔ ﺍﻟﻌﺭﺒﻴﺔ ﺍﻟﺴﻌﻭﺩﻴﺔ ....
ﺍﻟﻤﻨﺸﺂﺕ ﺍﻟﻤﻘﺎﻤﺔ ﻋﻠﻴﻬﺎ .ﻭﻟﻘﺩ ﺘﻡ ﺍﺴﺘﺨﺩﺍﻡ ﻫﺫﻩ ﺍﻟﻁﺭﻴﻘﺔ ﻓﻲ ﻤﻨﻁﻘﺔ ﺠﻴﺯﺍﻥ ﺤﻴﺙ ﺘﺤﺴﻨﺕ ﺍﻟﺨﻭﺍﺹ ﺍﻻﻨﻀﻐﺎﻁﻴﺔ ﻟﻠﺴﺒﺨﺔ ﺍﻟﻁﻴﻨﻴﺔ ﺒﻌﺩ ﺘﺤﻤﻴﻠﻬﺎ ﺒﺘﺭﺒﺔ ﺭﺩﻤﻴﺔ ﺴﻤﻜﻬﺎ ﺜﻼﺜﺔ ﺃﻤﺘﺎﺭ ﻭﻀﻌﺕ ﻋﻠﻰ ﺜﻼﺙ ﻤﺭﺍﺤل ﻜل ﻤﺭﺤﻠﺔ ﺒﺴﻤﻙ ﻤﺘﺭ ﻭﺍﺤﺩ ﻭﻟﻤﺩﺓ 12 ﺸﻬﺭﹰﺍ ،ﻭﻨﺘﺞ ﻋﻥ ﻫﺫﺍ ﺍﻟﺘﺤﻤﻴل ﻫﺒﻭﻁ ﻤﻘﺩﺍﺭﻩ 200ﻤﻠﻴﻤﺘﺭﹰﺍ] .[11ﻜﻤﺎ ﺴﺎﻋﺩﺕ ﻫﺫﻩ ﺍﻟﻁﺭﻴﻘﺔ ﻋﻠﻰ ﺯﻴﺎﺩﺓ ﻗﻭﺓ ﺍﻟﻘﺹ ﻟﻠﺘﺭﺒﺔ ﻭﻤﻘﺎﻭﻤﺔ ﺍﻟﺘﺭﺒﺔ ﻟﻼﺨﺘﺭﺍﻕ ﺇﻻ ﺃﻥ ﻤﻥ ﻋﻴﻭﺏ ﻼ ﻗﺩ ﻴﺼل ﺇﻟﻰ ﻋﺩﺓ ﺃﺸﻬﺭ ﻗﺒل ﺍﻟﺸﺭﻭﻉ ﻓﻲ ﻫﺫﻩ ﺍﻟﻁﺭﻴﻘﺔ ﺃﻨﻬﺎ ﺘﺴﺘﻐﺭﻕ ﻭﻗﺘﹰﺎ ﻁﻭﻴ ﹰ ﺇﻗﺎﻤﺔ ﺍﻟﻤﻨﺸﺂﺕ ﻋﻠﻰ ﺍﻟﺘﺭﺒﺔ .ﻭﺘﻌﺘﺒﺭ ﻋﻤﻠﻴﺔ ﺍﻟﺘﺤﻤﻴل ﺍﻟﻤﺴﺒﻕ ﺍﻟﺨﻴﺎﺭ ﺍﻷﻓﻀل ﻭﺍﻷﺭﺨﺹ ﻟﺘﺤﺴﻴﻥ ﺍﻟﺘﺭﺒﺔ ﺍﻟﻁﻴﻨﻴﺔ ﻭﺍﺴﺘﺨﺩﺍﻤﻬﺎ ﻜﺄﺴﺎﺱ ﻟﻠﻤﺒﺎﻨﻲ ﺫﺍﺕ ﺍﻷﺤﻤﺎل ﺍﻟﺨﻔﻴﻔﺔ ﺍﻟﻤﻜﻭﻨﺔ ﻤﻥ ﻁﺎﺒﻕ ﻭﺍﺤﺩ ﺃﻭ ﻁﺎﺒﻘﻴﻥ ﻭﺫﻟﻙ ﻤﺘﻰ ﻜﺎﻥ ﻫﻨﺎﻙ ﺍﻟﻭﻗﺕ ﺍﻟﻜﺎﻓﻲ ﻟﺘﻨﻔﻴﺫ ﺍﻟﻤﺸﺭﻭﻉ ﺍﻟﻤﺭﺍﺩ ﺇﻗﺎﻤﺘﻪ.
6ـ 3ﺘﺜﺒﻴﺕ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﺒﺎﺴﺘﺨﺩﺍﻡ ﺍﻻﻨﺴﺠﺔ ﺍﻟﺼﻨﺎﻋﻴﺔ : Geotextiles ﺇﻥ ﺍﺴﺘﺨﺩﺍﻡ ﺍﻷﻨﺴﺠﺔ ﺍﻟﺼﻨﺎﻋﻴﺔ ﻤﻥ ﺍﻟﻁﺭﻕ ﺍﻟﺤﺩﻴﺜﺔ ﻤﻘﺎﺭﻨﺔ ﺒﻁﺭﻕ ﺍﻟﺘﺜﺒﻴﺕ ﺍﻷﺨﺭﻯ .ﻭﻤﻥ ﺃﻫﻡ ﺘﻁﺒﻴﻘﺎﺕ ﻫﺫﻩ ﺍﻟﻁﺭﻴﻘﺔ ﻫﻭ ﺘﺤﺴﻴﻥ ﺴﻠﻭﻙ ﻁﺒﻘﺎﺕ ﺍﻟﺭﺼﻑ ﺍﻟﻤﺭﻨﺔ ﻟﻠﻁﺭﻕ ﻭﺫﻟﻙ ﺒﻭﻀﻊ ﺍﻷﻨﺴﺠﺔ ﺍﻟﺼﻨﺎﻋﻴﺔ ﺃﺴﻔل ﻁﺒﻘﺔ ﺍﻟﺘﺄﺴﻴﺱ ﺃﻭ ﺒﺩﺍﺨﻠﻬﺎ. ﻭﻟﻡ ﻴﺘﻡ ﺍﺴﺘﺨﺩﺍﻡ ﻫﺫﻩ ﺍﻟﻁﺭﻴﻘﺔ ﻟﺘﺤﺴﻴﻥ ﺨﻭﺍﺹ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﺍﻹ ﺤﺩﻴﺜﹸﺎ ﻭﺫﻟﻙ ﺒﺈﺠﺭﺍﺀ ﺍﻟﻌﺩﻴﺩ ﻤﻥ ﺍﻟﺘﺠﺎﺭﺏ ﺍﻟﻤﻌﻤﻠﻴﺔ ﻋﻠﻰ ﻋﻴﻨﺎﺕ ﻤﻥ ﺴﺒﺨﺔ ﺍﻟﺭﻴﺎﺱ ﻓﻲ ﺍﻟﻤﻨﻁﻘﺔ ﺍﻟﺸﺭﻗﻴﺔ] .[2ﺤﻴﺙ ُﻭﺠﺩ ﺃﻥ ﻗﻭﺓ ﺍﻟﺘﺤﻤل ﻟﻌﻴﻨﺎﺕ ﺍﻟﺘﺭﺒﺔ ﺍﻟﻤﺸﺒﻌﺔ ﺒﺎﻟﻤﺎﺀ ﻗﺩ ﺯﺍﺩﺕ ﻤﻥ 67ﻜﺠﻡ ﺇﻟﻰ 245ﻜﺠﻡ ﺒﻌﺩ ﺇﻀﺎﻓﺔ ﺍﻷﻨﺴﺠﺔ ﺍﻟﺼﻨﺎﻋﻴﺔ ﺃﻱ ﺒﺤﻭﺍﻟﻲ ،%266ﺒﻴﻨﻤﺎ ﺍﺘﻀﺢ ﺃﻥ ﺇﻀﺎﻓﺔ ﺍﻷﻨﺴﺠﺔ ﺍﻟﺼﻨﺎﻋﻴﺔ ﻟﻠﻌﻴﻨﺎﺕ ﺍﻟﻐﻴﺭ ﻤﺸﺒﻌﺔ ﻗﺩ ﺯﺍﺩﺕ ﻗﻭﺓ ﺍﻟﺘﺤﻤل ﻤﻥ 1160ﻜﺠﻡ ﺇﻟﻰ 1600ﻜﺠﻡ ﺃﻱ ﺒﺤﻭﺍﻟﻲ .%38ﻭﻤﻥ ﻫﺫﻩ ﺍﻟﻨﺘﺎﺌﺞ ﻴﺘﻀﺢ ﺃﻥ ﺍﺴﺘﺨﺩﺍﻡ ﺍﻷﻨﺴﺠﺔ ﺍﻟﺼﻨﺎﻋﻴﺔ ﻟﺘﺤﺴﻴﻥ ﻗﻭﺓ ﺍﻟﺘﺤﻤل ﻟﻠﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻴﻜﻭﻥ ﻤﺅﺜﺭﹰﺍ ﺒﺼﻭﺭﺓ ﺃﻓﻀل ﻋﻨﺩﻤﺎ ﺘﻜﻭﻥ ﺍﻟﺘﺭﺒﺔ ﻤﺸﺒﻌﺔ .ﻜﻤﺎ ﺘﻡ ﺍﻟﺘﻭﺼل ﻟﻨﺘﺎﺌﺞ ﻤﻤﺎﺜﻠﺔ ﻤﻥ ﻗﺒل
ﻋﺒﺩﺍﷲ ﺒﻥ ﺇﺒﺭﺍﻫﻴﻡ ﺍﻟﻤﻬﻴﺩﺏ
ﺒﺎﺤﺜﻴﻥ ﺁﺨﺭﻴﻥ ﻓﻲ ﺍﻟﻤﻌﻤل.
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ﺒﺎﺴﺘﺨﺩﺍﻡ ﻋﻴﻨﺎﺕ ﻤﻥ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺍﻟﻤﻨﻁﻘﺔ ﺍﻟﺸﺭﻗﻴﺔ ﺘﻡ ﺍﺨﺘﺒﺎﺭﻫﺎ
7ـ ﺍﻟﺨﻼﺼﺔ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻫﻲ ﺘﺭﺒﺔ ﻏﻨﻴﺔ ﺒﺎﻷﻤﻼﺡ ﺍﻟﻤﺘﺭﺴﺒﺔ ﻨﺘﻴﺠﺔ ﺘﺒﺨﺭ ﺍﻟﻤﺤﺘﻭﻯ ﺍﻟﻤﺎﺌﻲ ﻤﺨﻠﻔﺎ ﻭﺭﺍﺀﻩ ﺃﻤﻼﺤ ﹰﺎ ﻤﺨﺘﻠﻔﺔ ﺍﻟﺘﺭﺍﻜﻴﺏ ﺍﻟﻜﻴﻤﻴﺎﺌﻴﺔ .ﻭﺘﺘﺤﺩﺩ ﺍﻟﺭﺴﻭﺒﻴﺎﺕ ﻓﻲ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺜﻼﺙ ﻁﺒﻘﺎﺕ ﻫﻲ :ﺍﻟﻁﺒﻘﺔ ﺍﻟﻌﻠﻴﺎ ﺍﻟﻤﻌﺭﻭﻓﺔ ﺒﻘﺸﺭﺓ ﺍﻟﺴﺒﺨﺔ، ﻭﺍﻟﻁﺒﻘﺔ ﺍﻟﻭﺴﻁﻰ ﺍﻟﻘﺎﺒﻠﺔ ﻟﻼﻨﻀﻐﺎﻁ ،ﻭﺍﻟﻁﺒﻘﺔ ﺍﻟﺴﻔﻠﻴﺔ ﺍﻟﻤﻌﺭﻭﻓﺔ ﺒﻘﺎﻋﺩﺓ ﺍﻟﺴﺒﺨﺔ. ﻭﺘﺘﻤﻴﺯ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﺒﻤﻠﻭﺤﺔ ﻤﻴﺎﻫﻬﺎ ﺍﻟﻘﺭﻴﺒﺔ ﻤﻥ ﺍﻟﺴﻁﺢ ﻭﺘﻐﻴﺭ ﺍﻟﻜﺜﻴﺭ ﻤﻥ ﺨﻭﺍﺼﻬﺎ ﺍﻟﻔﻴﺯﻴﺎﺌﻴﺔ ﻭﺍﻟﻜﻴﻤﻴﺎﺌﻴﺔ ﺒﻴﻥ ﻤﺴﺎﻓﺎﺕ ﻗﺼﻴﺭﺓ ﻓﻲ ﺍﻻﺘﺠﺎﻫﻴﻥ ﺍﻷﻓﻘﻲ ﻭﺍﻟﺭﺃﺴﻲ ﻨﺘﻴﺠﺔ ﻟﻌﺩﻡ ﺘﺠﺎﻨﺴﻬﺎ ﻤﻤﺎ ﻴﺅﺩﻱ ﺇﻟﻰ ﺤﺩﻭﺙ ﺍﻟﻌﺩﻴﺩ ﻤﻥ ﺍﻟﻤﺸﺎﻜل ﺍﻟﻬﻨﺩﺴﻴﺔ ﻟﻠﻤﻨﺸﺂﺕ ﻭﺍﻟﻁﺭﻕ ﺍﻟﺘﻲ ﺘﻘﺎﻡ ﻋﻠﻴﻬﺎ .ﻭﺘﺘﻁﻠﺏ ﻁﺒﻴﻌﺔ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﺍﻟﻤﺤﺘﻭﻴﺔ ﻋﻠﻰ ﻜﻤﻴﺔ ﻜﺒﻴﺭﺓ ﻤﻥ ﺍﻷﻤﻼﺡ ﺇﺠﺭﺍﺀ ﺍﻟﻤﺯﻴﺩ ﻤﻥ ﺍﻟﺩﺭﺍﺴﺎﺕ ﻟﻐﺭﺽ ﺘﺤﺩﻴﺩ ﺍﻟﺨﻭﺍﺹ ﺍﻟﺤﻘﻴﻘﻴـﺔ ﻟﻠﺘﺭﺒـﺔ ﺍﻟﺴﺒﺨﺔ ﻷﻨﻬﺎ ﺘﺭﺒﺔ ﻏﻴﺭ ﻋﺎﺩﻴﺔ .ﻭﻟﺫﻟﻙ ﻓﻘﺩ ﺍﻗﺘﺭﺡ ﺒﻌﺽ ﻻ ﻤﻥ ﺍﻟﻌﺫﺒﺔ ﻜﺘﻌﺩﻴل ﻋﻠﻰ ﺍﻟﺒﺎﺤﺜﻴﻥ ] [28ﺇﺠﺭﺍﺀ ﺍﻟﺘﺠﺎﺭﺏ ﺒﺎﺴﺘﺨﺩﺍﻡ ﺍﻟﻤﻴﺎﻩ ﺍﻟﻤﺎﻟﺤﺔ ﺒﺩ ﹰ ﺍﻟﻁﺭﻕ ﺍﻟﺘﻲ ﺘﺘﻡ ﺒﻬﺎ ﺍﻟﺘﺠﺎﺭﺏ ﺍﻟﻤﻌﻤﻠﻴﺔ ﻟﺘﺤﺩﻴﺩ ﺍﻟﺨﻭﺍﺹ ﺍﻟﺠﻴﻭﺘﻜﻨﻴﻜﻴﺔ ﻟﻠﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ. ﻭﻤﻥ ﺍﻟﻤﻤﻜﻥ ﺘﻘﺴﻴﻡ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﺇﻟﻰ ﻨﻭﻋﻴﻥ ﺭﺌﻴﺴﻴﻥ ﻫﻤﺎ :ﺍﻟﺴﺒﺨﺔ ﺍﻟﺴﺎﺤﻠﻴﺔ ﺤﻭل ﺍﻟﺸﻭﺍﻁﺊ ﻭﺘﻭﺠﺩ ﻓﻲ ﺍﻟﻤﻨﻁﻘﺔ ﺍﻟﺸﺭﻗﻴﺔ ﻤﻥ ﺍﻟﻤﻤﻠﻜﺔ ﺤﻭل ﺍﻟﺨﻠﻴﺞ ﺍﻟﻌﺭﺒﻲ ﻭﻓﻲ ﺍﻟﻤﻨﻁﻘﺔ ﺍﻟﻐﺭﺒﻴﺔ ﺤﻭل ﺍﻟﺒﺤﺭ ﺍﻷﺤﻤﺭ ﻓﻲ ﻜل ﻤﻥ ﺠﺩﺓ ﻭﺠﻴﺯﺍﻥ ﻭﺃﺒﺤﺭ ﻭﺍﻟﻠﻴﺙ، ﻭﺍﻟﺴﺒﺨﺔ ﺍﻟﻘﺎﺭﻴﺔ ﺩﺍﺨل ﺍﻟﻴﺎﺒﺴﺔ ﻭﺘﻭﺠﺩ ﻓﻲ ﻭﺍﺩﻱ ﺍﻟﺴﺭﺤﺎﻥ ﻓﻲ ﺍﻟﻤﻨﻁﻘﺔ ﺍﻟﺸﻤﺎﻟﻴﺔ ﻤﻥ ﺍﻟﻤﻤﻠﻜﺔ ﻭﻓﻲ ﺃﺠﺯﺍﺀ ﻗﻠﻴﻠﺔ ﻤﻥ ﻤﻨﻁﻘﺔ ﺍﻟﻘﺼﻴﻡ ﻭﺍﻟﺭﺒﻊ ﺍﻟﺨﺎﻟﻲ. ﻭﻓﻲ ﻫﺫﺍ ﺍﻟﺒﺤﺙ ﺘﻡ ﺍﻟﺤﺩﻴﺙ ﻋﻥ ﺃﻤﺎﻜﻥ ﻭﺠﻭﺩ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺍﻟﻤﻤﻠﻜﺔ ﺍﻟﻌﺭﺒﻴﺔ ﺍﻟﺴﻌﻭﺩﻴﺔ ،ﻭﺨﻭﺍﺹ ﻫﺫﻩ ﺍﻟﺘﺭﺒﺔ ﻓﻲ ﻜل ﻤﻥ ﺍﻟﻤﻨﻁﻘﺔ ﺍﻟﺸﺭﻗﻴﺔ )ﺍﻟﺭﻴﺎﺱ،
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ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺍﻟﻤﻤﻠﻜﺔ ﺍﻟﻌﺭﺒﻴﺔ ﺍﻟﺴﻌﻭﺩﻴﺔ ....
ﺍﻟﻘﺭﻴﺔ ،ﺍﻟﻌﺯﻴﺯﻴﺔ،ﺭﺃﺱ ﺍﻟﻐﺎﺭ( ،ﻭﻓﻲ ﺠﻴﺯﺍﻥ ﻭﻓﻲ ﺍﻟﻤﻨﻁﻘﺔ ﺍﻟﻐﺭﺒﻴﺔ )ﺠﺩﺓ ﻭﺃﺒﺤﺭ ﻭﺍﻟﻠﻴﺙ( .ﺤﻴﺙ ﺃﻭﻀﺤﺕ ﺨﻭﺍﺹ ﻫﺫﻩ ﺍﻟﺴﺒﺨﺎﺕ ﻗﻭﺓ ﺘﺤﻤل ﺴﺒﺨﺔ ﺍﻟﺭﻴﺎﺱ ﻭﻤﻨﺎﺴﺒﺘﻬﺎ ﻟﻼﺴﺘﺨﺩﺍﻡ ﻜﻘﺎﻋﺩﺓ ﺘﺭﺍﺒﻴﺔ ﻟﻠﻁﺭﻴﻕ ،ﻭﺃﻥ ﻗﻭﺓ ﺘﺤﻤل ﺴﺒﺨﺔ ﺍﻟﻘﺭﻴﺔ ﻤﺘﻭﺴﻁﺔ ﺇﻟﻰ ﻋﺎﻟﻴﺔ ،ﺃﻤﺎ ﻗﻭﺓ ﺘﺤﻤل ﺴﺒﺨﺔ ﺍﻟﻌﺯﻴﺯﻴﺔ ﻓﻜﺎﻨﺕ ﻀﻌﻴﻔﺔ ﺇﻟﻰ ﻤﺘﻭﺴﻁﺔ، ﻭﺒﺎﻟﻨﺴﺒﺔ ﻟﺴﺒﺨﺔ ﺭﺃﺱ ﺍﻟﻐﺎﺭ ﻓﺈﻥ ﻗﻭﺓ ﺘﺤﻤﻠﻬﺎ ﺘﻌﺘﺒﺭ ﻀﻌﻴﻔﺔ ﺒﺸﻜل ﻋﺎﻡ .ﻭﺘﺘﻤﻴﺯ ﺴﺒﺨﺔ ﺠﻴﺯﺍﻥ ﺒﻭﺠﻭﺩ ﺍﻟﻁﺒﻘﺔ ﺍﻟﻭﺴﻁﻰ ﺍﻟﺘﻲ ﺘﺤﺘﻭﻱ ﻋﻠﻰ ﻨﺴﺒﺔ ﻋﺎﻟﻴﺔ ﻤﻥ ﺍﻟﻤﻭﺍﺩ ﺍﻟﻌﻀﻭﻴﺔ ﻭﺍﻟﺘﻲ ﺘﻌﺘﺒﺭ ﺍﻟﺴﺒﺏ ﺍﻟﺭﺌﻴﺴﻲ ﻟﻤﺸﺎﻜل ﺍﻟﻬﺒﻭﻁ ﺒﺴﺒﺏ ﺍﻨﻀﻐﺎﻁﻴﺘﻬﺎ ﺍﻟﻌﺎﻟﻴﺔ، ﻭﻴﻤﻜﻥ ﺘﻘﻠﻴل ﻤﻘﺩﺍﺭ ﺍﻟﻬﺒﻭﻁ ﻋﻥ ﻁﺭﻴﻕ ﻤﻌﺎﻟﺠﺘﻬﺎ ﺒﻭﺍﺴﻁﺔ ﻁﺭﻴﻘﺔ ﺍﻟﺘﺤﻤﻴل ﺍﻟﻤﺴﺒﻕ. ﻭﺘﻌﺘﺒﺭ ﺍﻟﺴﻌﺔ ﺍﻟﺘﺤﻤﻴﻠﻴﺔ ﻟﺴﺒﺨﺔ ﺠﺩﺓ ﻟﻠﻁﺒﻘﺔ ﺤﺘﻰ ﻋﻤﻕ ﻤﺘﺭﻴﻥ ﻀﻌﻴﻔﺔ ﻭﻟﻜﻥ ﻴﻤﻜﻥ ﻤﻌﺎﻟﺠﺘﻬﺎ ﺒﻭﺍﺴﻁﺔ ﺍﻟﺩﻤﻙ ﻜﻤﺎ ﻴﻤﻜﻥ ﺍﺴﺘﺨﺩﺍﻤﻬﺎ ﻜﻤﺎﺩﺓ ﺭﺩﻡ .ﻭﻴﻭﺠﺩ ﻨﻭﻋﺎﻥ ﻤﻥ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺃﺒﺤﺭ ﻫﻤﺎ ﺍﻟﺴﺒﺨﺔ ﺍﻟﻁﻴﻨﻴﺔ ﻭﺍﻟﺴﺒﺨﺔ ﺍﻟﺭﻤﻠﻴﺔ ،ﻭﺘﺘﻜﻭﻥ ﺍﻟﻁﺒﻘﺔ ﺍﻟﻭﺴﻁﻰ ﻟﻠﺴﺒﺨﺔ ﺍﻟﻁﻴﻨﻴﺔ ﻤﻥ ﻁﻴﻥ ﻟﻴﻥ ﺫﻱ ﺍﻨﻀﻐﺎﻁﻴﺔ ﻋﺎﻟﻴﺔ ﻭﻟﻜﻥ ﻴﻤﻜﻥ ﻤﻌﺎﻟﺠﺘﻪ ﺒﻭﺍﺴﻁﺔ ﻁﺭﻴﻘﺔ ﺍﻟﺘﺤﻤﻴل ﺍﻟﻤﺴﺒﻕ ﻻ ﺴﻴﻤﺎ ﺃﻥ ﺴﻤﻙ ﺍﻟﻁﺒﻘﺔ ﻗﻠﻴل )ﺤﻭﺍﻟﻲ 1.5ﻤﺘﺭﹰﺍ( .ﻭﺘﺘﻤﻴﺯ ﺴﺒﺨﺔ ﺍﻟﻠﻴﺙ ﺒﻘﻭﺓ ﺘﺤﻤﻠﻬﺎ ﻭﺍﻨﺨﻔﺎﺽ ﺍﻨﻀﻐﺎﻁﻴﺘﻬﺎ ﻭﻟﺫﻟﻙ ﻓﺈﻨﻪ ﻴﻤﻜﻥ ﺍﻟﺒﻨﺎﺀ ﻋﻠﻴﻬﺎ ﻤﺒﺎﺸﺭﺓ ﺒﺩﻭﻥ ﻤﻌﺎﻟﺠﺘﻬﺎ. ﻭﻗﺩ ﺘﻡ ﺍﻟﺘﻁﺭﻕ ﻜﺫﻟﻙ ﺇﻟﻰ ﺃﻫﻡ ﻁﺭﻕ ﻤﻌﺎﻟﺠﺔ ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻭﻨﺘﺎﺌﺞ ﺘﻁﺒﻴﻕ ﺒﻌﺽ ﻫﺫﻩ ﺍﻟﻁﺭﻕ ﻋﻠﻰ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺒﻌﺽ ﻤﻨﺎﻁﻕ ﻭﺠﻭﺩﻫﺎ ﻓﻲ ﺍﻟﻤﻤﻠﻜﺔ .ﻭﻗﺩ ﺘﺒﻴﻥ ﺃﻥ ﺇﻀﺎﻓﺔ ﺍﻷﺴﻤﻨﺕ ﻜﺎﻥ ﺫﺍ ﺃﺜﺭ ﻓﻌﺎل ﻓﻲ ﺘﺤﺴﻴﻥ ﺨﻭﺍﺹ ﺍﻟﺴﺒﺨﺔ ﺍﻟﺭﻤﻠﻴﺔ ،ﻜﻤﺎ ﺃﻥ ﺍﺴﺘﺨﺩﺍﻡ ﻁﺭﻴﻘﺔ ﺍﻟﺘﺤﻤﻴل ﺍﻟﻤﺴﺒﻕ ﻗﺩ ﻗﻠﻠﺕ ﻤﻥ ﻤﻘﺩﺍﺭ ﺍﻟﻬﺒﻭﻁ ﻟﻠﺴﺒﺨﺔ ﺍﻟﻁﻴﻨﻴﺔ ،ﻭﺃﻥ ﺍﺴﺘﺨﺩﺍﻡ ﺍﻷﻨﺴﺠﺔ ﺍﻟﺼﻨﺎﻋﻴﺔ ﻟﺘﺤﺴﻴﻥ ﻗﻭﺓ ﺍﻟﺘﺤﻤل ﻟﻠﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻴﻜﻭﻥ ﻤﺅﺜﺭﹰﺍ ﺒﺼﻭﺭﺓ ﺃﻓﻀل ﻋﻨﺩﻤﺎ ﺘﻜﻭﻥ ﺍﻟﺘﺭﺒﺔ ﻤﺸﺒﻌﺔ.
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ﻋﺒﺩﺍﷲ ﺒﻥ ﺇﺒﺭﺍﻫﻴﻡ ﺍﻟﻤﻬﻴﺩﺏ
اﻟﻤﺮاﺟﻊ ﺇﺒﺭﺍﻫﻴﻡ "ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﻴﺔ ﻓﻲ ﺍﻟﻤﻤﻠﻜـﺔ، ﺯﻏﻠﻭل؛ ﻋﺎﺼﻲ،ﻋﻤﺭ ﺴﻌﻴﺩ؛ ﺍﻟﻨﺠﺎﺭ، ﺍﻟﻌﻤﻭﺩﻱ .(1413) 62-56 :(2)6 ،ﺍﻟﻌﺭﺒﻴﺔ ﺍﻟﺴﻌﻭﺩﻴﺔ ﻭﻤﺸﺎﻜﻠﻬﺎ ﺍﻟﻬﻨﺩﺴﻴﺔ " ﻤﺠﻠﺔ ﺍﻟﻤﻬﻨﺩﺱ
Aiban, S.A. , Al-Abdul Wahhab, H. I. And Al-Amoudi, O. S. B. “Identification, Evaluation and Improvement of Eastern Saudi Soils For Constructional Purposes", Final Report Project No. AR-14-61, King Abdulaziz City for Science and Technology, Riyadh, Saudi Arabia (1999). Tomilson, M. J. " Middle East - Highway and Airfield Pavements" The Quarterly Journal of Engineering Geology, 11 : 65-73 (1978). Shin, E. A. " Sedimentary Accretion along the Leeward, SE Coast of Qatar Peninsula, Persian Gulf" The Persian Gulf, Ed. By B.H. Purser, Springer-Verlag, 109-209 (1970). Newbery, J. and Subramaniam, A. S. " Middle East - Sewerage Projects for Coastal Towns of the Libyan Arab Republic" The Quarterly Journal of Engineering Geology, 11 : 101-112 (1978). Horta, J. C. " Characterization of Calcrete and Gypcrete as Pavement Materials" Proceedings of the International Conference on Roads and Road Transport Problems, ICORT-88, New Delhi, India, 781-788 (1988). Akpokodje, E. G. " The Stabilization of Some Arid Zones Soils with Cement and Lime" The Quarterly Journal of Engineering Geology, 18 : 173-180 (1985). Kinsman. D.J.J " Modes of Formation, Sedimentary Associations, And Diagnostic Features of Shallow-Water and Supratidal Evaporites" The American association of petroleum Geologist Bulletin, 53(4) : 830-840 (1969). Lund, O. L. and Ramsey, W. J. "Experimental Lime Stabilization in Nebraska" Highway Research Board, HRB, 231 : 24-59 (1983). Farwana, T. A. and Majidzadeh, K. " An Investigation into the Use of Emulsified Asphalt in the Stabilization of Sandy Sabkha" , Proceedings of the 3rd IRF Middle East Regional Meeting, 3: 3.355-3.379 (1988). Dhowian , A.W and Erol, A.O " Ground Conditions and Associated Structural Problems In Tabuk and Jazan Regions" Final Report Project No. AR8-106, King Abdul Aziz City for Science and Technology, Riyadh, Saudi Arabia (1993). Ellis, C.I. "Arabian Salt-Bearing Soil (Sabkha) as an Engineering Material", Transport and Road Research Laboratory, TRRL Report LR 523, UK, (1973). Fookes, P. G. and Collis, L." Problems in the Middle East" Concrete, 9(7): 1217 (1975). Akili, W. " On Sabkha Sands of Eastern Saudi Arabia " Proceedings, Symposium on Geotechnical Problems in Saudi Arabia, Riyadh, Saudi Arabia, 2 : 775-796 (1981). Fookes, P.G., French, W.J. and Price, S.M. " The Influence of Ground and Groundwater Geochemistry on Construction in the Middle East" The Quarterly Journal of Engineering Geology, 18 : 101-128 (1985). Bush, P. " Some Aspects of the Diagenetic History of the Sabkha in Abu Dhabi, Persian Gulf" in: Purser, B.H., The Persian Gulf, Springer-Verlag, Austria, 395407 (1973).
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.... ﺍﻟﺘﺭﺒﺔ ﺍﻟﺴﺒﺨﺔ ﻓﻲ ﺍﻟﻤﻤﻠﻜﺔ ﺍﻟﻌﺭﺒﻴﺔ ﺍﻟﺴﻌﻭﺩﻴﺔ Levy, Y. " The Origin and Evolution of Brine in Coastal Sabkhas, Northern Sin" Journal of Sedimentary Petrology, 47(1) : 451-462 (1977). James, A.N. and Little, A. L. " Geotechnical Aspects of Sabkha at Jubail, Saudi Arabia" The Quarterly Journal of Engineering Geology, 27: 83-121 (1994). Johnson,H.S., Kamil ,M.R, Pierson , G.O. and Ramsay , J.B." Sabkhas of Eastern Saudi Arabia" in Al-Sayyari, S.S. and Zolt, J.G. (Ed.), Quarterly period in Saudi Arabia, Springer, Berlin, 84-93 (1978). Abu-Taleb, M.G. and Egeli, I. " Some Geotechnical Problems in the Eastern Province of Saudi Arabia", Proceedings,Symosium on Geotechnical Problems in Saudi Arabia, Riyadh, Saudi Arabia, 2 : 799-811 (1981). Al-Amoudi, O.S.B., Abduljauwad, S.N., El-Naggar, Z.R. and Rasheeduzzafar " Response of Sabkha to Laboratory Tests: A Case Study" Engineering Geology, 33:111-125 (1992). Abduljauwad, S.N. and Al-Amoudi, O.S.B. " Geotechnical Behaviour of Saline Sabkha Soils" Geotechnique, 45(3): 425-445 (1995). Ghazali, F.M, Fatani , M.N. and Khan , A.M. " Geotechnical Properties Of Sabkha Soils of Jeddah , Saudi Arabia" , Proceedings of the Second Saudi Engineers conference , Dhahran, Saudi Arabia, 1:286-307 (1985 ). Hossain, D. and Ali, K. M. " Geotechnical and Geochemical Characteristics of Obhor Subsoil", Faculty of Earth Science Bulletin No.7 , King Abdul Aziz University (1987) . Hossain, D. and Ali, K. M." Shear Strength and Consolidation Characteristics of Obhor Sabkha, Saudi Arabia ", Quarterly Journal of Engineering Geology, 21: 347-359 (1988). Abou Al Heija, M. K. and Shehata, W.M. " Engineering Properties of Al-Lith sabkha, Saudi Arabia " 5 th. International IAEG Congress ,Buenos Aires, 935941(1986). Abduljauwad, S. N. , Bayomy, F., Al-Shaikh, A. M. and Al-Amoudi, O.S.B. " Influence of Geotextiles on Performance of Saline Sebkha Soils" , Journal of Geotechnical Engineering, ASCE, 120(11) : 1939-1960 (1994). Al-Amoudi, O.S.B and Abduljauwad, S. N. " Suggested modifications to ASTM Standard Methods When Testing Arid, Saline Soils" , ASTM Geotechnical Testing Journal, 17(2) : 243-253 (1994).
81 [17] [18] [19] [20] [21] [22] [23] [24] [25] [26] [27] [28]
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ﻋﺒﺩﺍﷲ ﺒﻥ ﺇﺒﺭﺍﻫﻴﻡ ﺍﻟﻤﻬﻴﺩﺏ
Sabkha Soil in the Kingdom of Saudi Arabia : Characteristics and Treatment ABDULLAH I. AL-MHAIDIB Departement of Civil Engineering, College of Engineering, King Saud University, Riyadh, Saudi Arabia ABSTRACT. Sabkha soil is found along the Arabian Gulf and Red Sea coasts of Saudi Arabia and in small areas inside the Kingdom. It exists at many locations of the coastal plains of the Eastern Province and along the western shores at Jizan, Jeddah, Obhor and Al-Lith. Sabkha soil is also reported to exist in Wadi As Sirhan in the north and in small areas in Al-Qassim region and the Empty Quarter. The distinguishing features of sabkha soil are the presence of shallow and highly concentrated brines and the variability of its geotechnical characteristics in both the horizontal and vertical directions. These features cause several engineering problems in roads and buildings constructed on the sabkha. There are primarily two types of sabkha soils: coastal and continental. Coastal sabkhas exist in Eastern Province along the Arabian Gulf and in the western shores along the Red Sea. Continental sabkhas are formed inside the land away from the sea and found in Wadi As Sirhan in the north and in small areas in Al-Qassim region and the Empty Quarter. This paper presents a brief description of sabkha soil, its occurrence around the world, its types as well as the main factors affecting it. It also presents the distribution of sabkha soil in Saudi Arabia and the geotechnical and chemical characteristics of sabkha soil in the Eastern Province and in Jizan, Jeddah, Obhor as well as Al-Lith in the western regions. The paper is concluded by mentioning several techniques for treating sabkha soil and presents the results of some of these techniques which were used to treat sabkha soil in some regions.