ﺑﺮرﺳﯽ رﻓﺘﺎر ﻟﻮﻟﻪﻫﺎي ﻓﻮﻻدي ﻣﺪﻓﻮن ﺗﻮزﯾﻊ ﮔﺎز در اﻧﻮاع ﺧﺎكﻫﺎ در اﺛﺮ اﻧﺘﺸﺎراﻣﻮاج ﻟﺮزهاي

Behaviour Verification of Gas Transfer Buried Steel Pipelines by Propagation of Seismic Waves in Soil Types

در ﻣﻄﺎﻟﻌﺎت اﻧﺠﺎم ﺷﺪه، اﺛﺮات زﻟﺰﻟﻪ ﺑﺮ روي ﺧﻄﻮط ﻟﻮﻟﻪ ﻣﺪﻓﻮن ﺑﻪ دو دﺳﺘﻪ اﺛﺮ اﻧﺘﺸﺎر اﻣﻮاج )آﺛﺎر دﯾﻨﺎﻣﯿﮑﯽ( و اﺛﺮ ﺗﻐﯿﯿﺮ ﻣﮑﺎن ﭘﺎﯾﺪار زﻣﯿﻦ )آﺛﺎر اﺳﺘﺎﺗﯿﮑﯽ( ﺗﻘﺴﯿﻢ ﺑﻨﺪي ﻣﯽﺷﻮﻧﺪ. ﺑﻪ ﻋﺒﺎرﺗﯽ ﺧﻄﺮات ﻟﺮزه اي ﺑﻪ دو دﺳﺘﻪ ﺧﻄﺮات ﻧﺎﺷﯽ از اﻧﺘﺸﺎر اﻣﻮاج و ﺗﻐﯿﯿﺮﻣﮑﺎن داﺋﻤﯽ زﻣﯿﻦ )PGD( ﺗﻘﺴﯿﻢ ﻣﯽ ﺷﻮﻧﺪ. ﺧﻄﺮ ﺗﻐﯿﯿﺮ ﻣﮑﺎن ﭘﺎﯾﺪار زﻣﯿﻦ )PGD( ﺑﺮاﺳﺎس ﮐﺮﻧﺶ اﯾﺠﺎد ﺷﺪه در ﻟﻮﻟﻪ ﺑﻪ ﻋﻠﺖ ﻟﻐﺰش، ﻧﺸﺴﺖ زﻣﯿﻦ ﯾﺎ رواﻧﮕﺮاﯾﯽ ﻧﺎﺷﯽ از ﮔﺴﺘﺮش ﺟﺎﻧﺒﯽ ﻣﺸﺨﺺ ﻣﯽﺷﻮد و ﺧﺮاﺑﯽﻫﺎي ﻧﺎﺷﯽ از آن ﻣﻌﻤﻮﻻً در ﻧﺎﺣﯿﻪ ﻣﺤﺪودي از ﺷﮑﺴﺖ زﻣﯿﻦ اﻣﺎ ﺑﻪ ﺷﮑﻞ ﺷﺪﯾﺪي اﺗﻔﺎق ﻣﯽاﻓﺘﺪ. ﻣﻬﻤﺘﺮﯾﻦ ﭘﺎراﻣﺘﺮ ﺑﺮاي ﺗﻌﯿﯿﻦ ﺳﻄﺢ ﻋﻤﻠﮑﺮد و ﻣﯿﺰان ﺧﺮاﺑﯽ ﺧﻄﻮط ﻟﻮﻟﻪ ﻣﺪﻓﻮن در ﻫﻨﮕﺎم وﻗﻮع زﻟﺰﻟﻪ، ﻣﻘﺪار ﺣﺪاﮐﺜﺮ ﮐﺮﻧﺶ ﻣﯽﺑﺎﺷﺪ. آﺋﯿﻦﻧﺎﻣﻪ ﻫﺎي ﺷﺮﯾﺎنﻫﺎي ﺣﯿﺎﺗﯽ ﻧﯿﺰ ﺑﺎ ﺑﺮرﺳﯽ ﻣﻘﺪار ﺣﺪاﮐﺜﺮ ﮐﺮﻧﺶ، ﺑﻪ ﺑﺮرﺳﯽ رﻓﺘﺎر ﻟﺮزه اي ﺧﻄﻮط ﻟﻮﻟﻪ ﻣﺪﻓﻮن ﭘﺮداﺧﺘﻪاﻧﺪ. در اﯾﻦ ﻣﻄﺎﻟﻌﻪ ﺑﺎ اﺳﺘﻔﺎده از ﻧﺮم اﻓﺰارAbaqus روﺷﯽ ﺑﺮاي ﻣﺤﺎﺳﺒﻪ ﺣﺪاﮐﺜﺮ ﮐﺮﻧﺶ ﺑﻪ وﺟﻮد آﻣﺪه در ﻟﻮﻟﻪ ﻫﺎي ﻓﻮﻻدي ﻣﺪﻓﻮن اﻧﺘﻘﺎل ﮔﺎز در ﺧﺎك ﺑﺮ ﺣﺴﺐ ﭘﺎراﻣﺘﺮﻫﺎي ﻣﺤﺘﻮي اﻧﺮژي زﻟﺰﻟﻪ ﻣﺎﻧﻨﺪ ﺷﺪت آرﯾﺎس و ﺷﺪت ﻃﯿﻔﯽ ﻫﺎوزﻧﺮ ﮐﻪ ﺑﺎ اﺳﺘﻔﺎده از ﺷﺘﺎب ﻧﮕﺎﺷﺖ ﻫﺎ ﺑﺪﺳﺖ ﻣﯽ آﯾﺪ اراﺋﻪ ﺷﺪه اﺳﺖ. ﺳﭙﺲ ﺑﻪ ﻣﻨﻈﻮر اراﺋﻪ ﯾﮏ راﺑﻄﻪ واﺣﺪ ﺑﺮاي ﻧﻤﺎﯾﺶ ارﺗﺒﺎط ﺑﯿﻦ ﺣﺪاﮐﺜﺮ ﮐﺮﻧﺶ ﻟﻮﻟﻪ ﻫﺎي ﻓﻮﻻدي و ﭘﺎراﻣﺘﺮﻫﺎي ﻣﺤﺘﻮي اﻧﺮژي زﻟﺰﻟﻪ SI, AI, PGV*te/PGD)( از ﭘﺎراﻣﺘﺮT/L )ﻧﺴﺒﺖ ﭘﺮﯾﻮد اﻣﻮاج ﺑﺮﺷﯽ ﺧﺎك ﺑﻪ ﻃﻮل ﻟﻮﻟﻪ( اﺳﺘﻔﺎده ﮔﺮدﯾﺪ و ﻣﻘﺎدﯾﺮ a وb ) ﺿﺮاﯾﺐ ﻧﻤﻮدارﻫﺎي ﺑﺮازش داده ﺷﺪه( در ﻫﺮ ﺑﺨﺶ ﺑﺮ اﺳﺎس اﯾﻦ ﭘﺎراﻣﺘﺮ ﺑﯿﺎن ﺷﺪه اﺳﺖ.

The most important parameter for determining the level of performance and breakdown of buried pipes in the case of earthquake is the maximum value of strain. Vital arteries code, while studying the maximum value of strain, have addressed the seismic behavior of buried pipelines. Static methods don’t have the ability to consider the transient strain effect in their results, so it is necessary to consider another method in determining maximum strain. From the suggested methods to determine the maximum strain in buried pipes during earthquake is nonlinear dynamic analysis of pipes and the soil around it. In this study, using Abaqus software, we have presented a method to calculate the maximum strain of buried steel pipes for gas transfer in soil according to the parameters including earthquake energy like Arias intensity and Housner spectral intensity and using accelerograms. Analyses performed according to dynamic method is nonlinear and modeling has been done for three different lengths of gas transfer buried steel pipes in soil, with the internal pressure using different accelerograms for types of soil in Iran 2800 code. Then, in order to present a united relation to show the relationship between maximum strain of steel pipes and parameters including earthquake energy, in order to apply the considered relation for buried pipes with different lengths and different soils, we have used T/L parameter and the values of a and b (coefficients of fitted diagrams) in each section is expressed according to this parameter.