The application of the wellhead suction anchor in the second production test of natural gas hydrates(NGHs)in the South China Sea(SCS)was met with success.This design incorporates a central conductor guide pipe,which d...The application of the wellhead suction anchor in the second production test of natural gas hydrates(NGHs)in the South China Sea(SCS)was met with success.This design incorporates a central conductor guide pipe,which distinguishes it from traditional suction foundations.However,this addition resulted in a relatively high penetration resistance and a shallower penetration depth at the self-weight penetration stage.To mitigate this issue,the current study proposes an optimized design where the end of the suction foundation is sharpened.The installation characteristics of the traditional suction foundation and new suction foundation during self-weight penetration into sand are studied through laboratory tests and theoretical analysis.The flat and sharpened bottom shapes are considered in the traditional and new suction models.The effects of the initial penetration velocity on the initial penetration depth and soil plug and impact cavity characteristics are systematically studied.The results show that the self-weight penetration depth of the foundation with a sharpened bottom is 44.5%deeper than that of the foundation with a flat bottom.There are cavities around the foundation at the self-weight penetration stage,and the penetration depth is overestimated by 15%-30%.Finally,a model for predicting the penetration depth of the new suction foundation is proposed.展开更多
During the self-weight penetration process of the suction foundation on the dense sand seabed,due to the shallow penetration depth,the excess seepage seawater from the outside to the inside of the foundation may cause...During the self-weight penetration process of the suction foundation on the dense sand seabed,due to the shallow penetration depth,the excess seepage seawater from the outside to the inside of the foundation may cause the negative pressure penetration process failure.Increasing the self-weight penetration depth has become an important problem for the safe construction of the suction foundation.The new suction anchor foundation has been proposed,and the self-weight penetration characteristics of the traditional suction foundation and the new suction anchor foundation are studied and compared through laboratory experiments and analysis.For the above two foundation types,by considering five foundation diameters and two bottom shapes,20 models are tested with the same penetration energy.The effects of different foundation diameters on the penetration depth,the soil plug characteristics,and the surrounding sand layer are studied.The results show that the penetration depth of the new suction foundation is smaller than that of the traditional suction foundation.With the same penetration energy,the penetration depth of the suction foundation becomes shallower as the diameter increases.The smaller the diameter of the suction foundation,the more likely it is to be fully plugged,and the smaller the height of the soil plug will be.In the stage of self-weight penetration,the impact cavity appears around the foundation,which may affect the stability of the suction foundation.展开更多
基金financially supported by the Key-Area Research and Development Program of Guangdong ProvinceChina(Grant No.2022B0101100001)+3 种基金the Marine Economic Development Special Program of Guangdong province(Six Major Marine Industries):Research and Demonstration of Critical Technologies for Comprehensive Prevention and Control of Natural Disaster in Offshore Wind FarmsChina(Grant No.29[2023])the Guangxi Key Laboratory of Disaster Prevention and Mitigation and Engineering SafetyChina(Grant No.2020ZDK002)。
文摘The application of the wellhead suction anchor in the second production test of natural gas hydrates(NGHs)in the South China Sea(SCS)was met with success.This design incorporates a central conductor guide pipe,which distinguishes it from traditional suction foundations.However,this addition resulted in a relatively high penetration resistance and a shallower penetration depth at the self-weight penetration stage.To mitigate this issue,the current study proposes an optimized design where the end of the suction foundation is sharpened.The installation characteristics of the traditional suction foundation and new suction foundation during self-weight penetration into sand are studied through laboratory tests and theoretical analysis.The flat and sharpened bottom shapes are considered in the traditional and new suction models.The effects of the initial penetration velocity on the initial penetration depth and soil plug and impact cavity characteristics are systematically studied.The results show that the self-weight penetration depth of the foundation with a sharpened bottom is 44.5%deeper than that of the foundation with a flat bottom.There are cavities around the foundation at the self-weight penetration stage,and the penetration depth is overestimated by 15%-30%.Finally,a model for predicting the penetration depth of the new suction foundation is proposed.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.52001337 and 41907244)the Guangxi Key Laboratory of Disaster Prevention and Mitigation and Engineering Safety,China(Grant No.2020ZDK002)the Key Program of Marine Economy Development(Six Marine Industries)Special Foundation of Department of Natural Resources of Guangdong Province,China(GDNRC[2020]028,GDOE[2019]A19).
文摘During the self-weight penetration process of the suction foundation on the dense sand seabed,due to the shallow penetration depth,the excess seepage seawater from the outside to the inside of the foundation may cause the negative pressure penetration process failure.Increasing the self-weight penetration depth has become an important problem for the safe construction of the suction foundation.The new suction anchor foundation has been proposed,and the self-weight penetration characteristics of the traditional suction foundation and the new suction anchor foundation are studied and compared through laboratory experiments and analysis.For the above two foundation types,by considering five foundation diameters and two bottom shapes,20 models are tested with the same penetration energy.The effects of different foundation diameters on the penetration depth,the soil plug characteristics,and the surrounding sand layer are studied.The results show that the penetration depth of the new suction foundation is smaller than that of the traditional suction foundation.With the same penetration energy,the penetration depth of the suction foundation becomes shallower as the diameter increases.The smaller the diameter of the suction foundation,the more likely it is to be fully plugged,and the smaller the height of the soil plug will be.In the stage of self-weight penetration,the impact cavity appears around the foundation,which may affect the stability of the suction foundation.
