黃河廢棄水下三角洲地基土對平臺插拔樁的響應(yīng)
發(fā)布時間：2019-06-27 20:09
【摘要】：1976年黃河改走清水溝流路后，黃河廢棄的釣口流路水下三角洲遭到強(qiáng)烈蝕退，岸灘沖刷很快，水深加大，海岸線大幅度后退，原有沉積地貌單元遭到破壞和夷平。海底滑坡、沉陷、斷裂、沖蝕溝槽、差異沖刷、粉土液化等海底不穩(wěn)定因素均有發(fā)生，這些海底不穩(wěn)定因素對油田開發(fā)帶來了巨大挑戰(zhàn)。海洋石油鉆井平臺在施工過程中，發(fā)生過樁腿刺穿、滑移甚至平臺傾覆，造成了災(zāi)難性海洋工程事故。 本論文依托多年積累的井場路由調(diào)查資料，研究了黃河廢棄水下三角洲地基土的強(qiáng)度特征及分布規(guī)律。研究區(qū)近十年來整體處于沖刷狀態(tài)，4-10m等深線之間的水下岸坡區(qū)平均沖刷大于2m。研究區(qū)淺部地基土主要為近期三角洲相的粉土和淤泥、淤泥質(zhì)粉質(zhì)粘土和早期的河湖沼澤相的粉質(zhì)粘土、粉細(xì)砂及粉土。海底表層沉積物主要類型有粉土和淤泥、淤泥質(zhì)粉質(zhì)粘土。表層粉土，具有較高的力學(xué)強(qiáng)度，厚層粉土可以作為插樁式鉆井平臺的持力層；淤泥、淤泥質(zhì)粉質(zhì)粘土屬于軟弱土，不能滿足插樁式鉆井平臺的要求。河湖相沉積的粉細(xì)砂、粉土，厚度一般大于10m，是插樁式鉆井平臺在該區(qū)理想的持力層。 根據(jù)地基土破壞的一般形式和特征，分析了樁靴式鉆井平臺插拔樁過程中地基土的破壞形式和特征。插拔樁過程是動態(tài)貫入過程，樁端及樁靴周圍地基土體受到強(qiáng)烈擾動，地基土破壞主要以沖剪破壞為主，土中并不出現(xiàn)明顯的連續(xù)滑動面，該過程與土體靜力學(xué)狀態(tài)下土體整體破壞存在較大區(qū)別。在分析了插樁過程中土體的破壞形式基礎(chǔ)上，根據(jù)極限平衡理論，假定破壞面的方法，推導(dǎo)出了均勻和雙層地基土中基于被動土壓力的插樁阻力計(jì)算公式。 極限承載力的分析計(jì)算建立在土體整體剪切破壞模式上，給出了土體極限狀態(tài)下的承載力。本文推導(dǎo)出的均勻土中和雙層地基土中的插樁計(jì)算公式，建立在土體沖剪破壞模式上，給出了土體沖剪破壞下的插樁阻力。二者與實(shí)際插樁阻力存在一定的差距，分別給出了插樁阻力的上限和下限。插樁阻力分析計(jì)算過程中采用假設(shè)破壞面更接近于插樁過程土體的破壞模式，實(shí)例計(jì)算結(jié)果也表明該方法計(jì)算的插樁阻力較以前的極限承載力更接近于實(shí)際插樁阻力，豐富了樁靴式鉆井平臺插樁深度預(yù)測方法。 根據(jù)插拔樁后井場的調(diào)查資料，分析了地基土經(jīng)歷插拔樁過程后的變化特征，探討了樁坑內(nèi)土體的強(qiáng)度恢復(fù)機(jī)理。地基土經(jīng)歷插拔樁過程后，在海底形成一定大小和深度的樁坑，在水動力作用下，樁坑逐漸被夷平。在淺地層聲學(xué)記錄上表現(xiàn)為地層反射面的中斷，尚未夷平的樁坑在聲納圖像上表現(xiàn)為近視圓形的凹坑。分析結(jié)果表明地基土經(jīng)歷插拔樁過程后工程性質(zhì)發(fā)生了較大變化：粉土經(jīng)歷插拔樁過程后，樁穴內(nèi)的含水量一般小于樁穴外的含水量；樁底下粉土的含水量比周邊粉土的含水量小。樁穴內(nèi)的粉土的壓縮模量一般大于樁穴外地基土的壓縮模量；軟粘土的壓縮模量一般小于樁坑周邊地基土的壓縮模量。研究認(rèn)為，粉土是研究區(qū)樁靴式鉆井平臺的主要的持力層，具有良好的排水條件，經(jīng)歷插拔樁后的樁坑內(nèi)的粉土強(qiáng)度一般大于或接近周圍土的強(qiáng)度。軟粘土由于排水條件很弱，插樁過程中受到擾動破壞，，強(qiáng)度降低。受到擾動的地基土強(qiáng)度恢復(fù)過程復(fù)雜，影響因素主要有再沉積作用、自身的壓縮固結(jié)、沙土液化和人工預(yù)壓。需要重復(fù)插樁的井場，地基土變化由于經(jīng)歷了插拔樁的過程較原始地層復(fù)雜，為了提高地基土的強(qiáng)度，可以采取預(yù)壓的方式提高地基土的承載力。 近年來，隨著海洋石油的開發(fā)活動加劇，研究區(qū)內(nèi)平臺插拔樁作業(yè)頻繁，地基土受到擾動和破壞，從而使得本來就復(fù)雜的井場地層情況變得更為復(fù)雜。雖然在海洋水動力作用下，地基土強(qiáng)度會恢復(fù)，但由于其強(qiáng)度與周邊土體強(qiáng)度存在差別，后續(xù)平臺插拔樁施工作業(yè)過程中存在較大的安全隱患。進(jìn)一步研究受到擾動破壞土體的工程性質(zhì)變化及其對平臺插樁的影響，有助于減少工程事故的發(fā)生。
[Abstract]:After the Yellow River was changed to the clear water channel in 1976, the underwater delta of the abandoned fishing-port flow channel of the Yellow River was strongly eroded, and the water depth increased and the coastline greatly retreated, and the original sedimentary geomorphic unit was damaged and flattened. The unstable factors such as the submarine landslide, the subsidence, the fracture, the erosion groove, the differential scouring, the liquefaction of the silt and the like have taken place, and the unstable factors of the seabed have brought great challenges to the development of the oil field. In the course of construction, the offshore oil drilling platform has caused a catastrophic ocean engineering accident. In this paper, the strength characteristics and distribution of the foundation soil of the waste water delta in the Yellow River have been studied based on the survey data of well pads accumulated over the years. Law. The study area is in a flush state in the last ten years, and the average scour of the underwater land area between the 4-10m isobath is greater than the average. The foundation soil in the shallow part of the study area is mainly silt and silt of the near-term delta phase, silty clay of the silt and the silty clay and fine sand of the early river and lake swamps. Silty soil. The main types of surface sediments in the bottom of the sea are silt, silt and silty clay. The silty soil of the surface layer has higher mechanical strength, and the thick layer of silt can be used as the bearing layer of the pile-in type drilling platform; the silt and the silty clay belong to the soft soil and can not meet the pile-in type drilling platform The fine sand, silt and the thickness of the river and lake facies are generally more than 10m. It is the ideal holding platform for the pile-type drilling platform in this area. The general form and characteristics of the base soil failure in the base area are analyzed, and the damage of the foundation soil during the process of the pile-shoe type drilling platform is analyzed. The process of the plug-in pile is the dynamic penetration process, the soil body around the pile end and the pile shoe is strongly disturbed, the damage of the foundation soil is mainly caused by the impact and shear, and no obvious continuous sliding surface appears in the soil, and the process and the soil body in the static state of the soil are damaged as a whole. Based on the analysis of the damage form of the soil in the process of inserting the pile, according to the limit equilibrium theory, the method of the failure surface is assumed, and the plug-in resistance based on the passive earth pressure in the uniform and double-layer foundation soil is derived. The calculation of the ultimate bearing capacity is based on the overall shear failure mode of the soil, and the soil mass is given. In this paper, the calculation formula of the pile-in pile in the soil and the double-layer foundation soil is derived, and the shear-shear failure mode of the soil is established. There is a certain gap between the resistance of the inserted pile and the actual pile-in resistance, and the plug-in pile is given separately. The upper limit and the lower limit of the resistance are calculated. In the process of pile resistance analysis, it is assumed that the failure surface is closer to the failure mode of the soil in the process of inserting the pile, and the calculation results of the example also show that the pile resistance calculated by the method is more than that of the previous limit bearing capacity. It is close to the actual pile-in resistance, and enriches the pile-shoe type drilling platform. According to the survey data of the well pad after the plug-in pile, the change characteristics of the foundation soil after the process of inserting and pulling the pile are analyzed, and the pile-pile depth prediction method is discussed. The strength recovery mechanism of the soil in the pit. After the foundation soil is subjected to the process of plugging and pulling the pile, a pile pit of a certain size and depth is formed on the sea floor, The pile pit is gradually razed under the action of the surface of the formation in the acoustic recording of the shallow formation. The pile pits that have not yet been flattened are in the sonar image. The results show that the water content in the pile cavity is less than the water content outside the pile and the water content of the foundation soil under the pile is less than that of the pile. and the compressive modulus of the soft clay is generally smaller than the compressive modulus of the ground soil outside the pile, and the compressive modulus of the soft clay is generally smaller than that of the pile, The compressive modulus of the foundation soil at the periphery of the pit is studied. The research is that the silt is the main bearing stratum of the research area pile shoe type drilling platform, and has good drainage conditions, and the strength of the silt in the pile pit after the extraction and removal of the pile is generally Greater than or near the strength of the surrounding soil. The soft clay is in the process of pile-in due to poor drainage conditions It is disturbed by the disturbance, and the intensity is reduced. The soil strength recovery process of the disturbed foundation is complicated, and the influencing factors mainly have the effect of re-excitation and the compression and solid of the soil. In order to improve the strength of the foundation soil, pre-pressing can be adopted to improve the strength of the foundation soil. The bearing capacity of the foundation soil is improved. In recent years, with the development of the offshore oil, the operation of the platform plug-in pile in the research area is frequent, and the foundation soil is disturbed and destroyed, so that the foundation soil can be complex The formation condition of the well pad becomes more complicated. Although the strength of the foundation soil can be restored under the action of the ocean water, the construction of the post-platform plug-in pile due to the difference in the strength of the soil and the strength of the surrounding soil There is a great potential safety hazard in the operation process. The change of the engineering property and the shadow of the platform plug-in by the disturbance are further studied.
【學(xué)位授予單位】：中國海洋大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2014
【分類號】：TU473.1
本文編號：2507110
[Abstract]:After the Yellow River was changed to the clear water channel in 1976, the underwater delta of the abandoned fishing-port flow channel of the Yellow River was strongly eroded, and the water depth increased and the coastline greatly retreated, and the original sedimentary geomorphic unit was damaged and flattened. The unstable factors such as the submarine landslide, the subsidence, the fracture, the erosion groove, the differential scouring, the liquefaction of the silt and the like have taken place, and the unstable factors of the seabed have brought great challenges to the development of the oil field. In the course of construction, the offshore oil drilling platform has caused a catastrophic ocean engineering accident. In this paper, the strength characteristics and distribution of the foundation soil of the waste water delta in the Yellow River have been studied based on the survey data of well pads accumulated over the years. Law. The study area is in a flush state in the last ten years, and the average scour of the underwater land area between the 4-10m isobath is greater than the average. The foundation soil in the shallow part of the study area is mainly silt and silt of the near-term delta phase, silty clay of the silt and the silty clay and fine sand of the early river and lake swamps. Silty soil. The main types of surface sediments in the bottom of the sea are silt, silt and silty clay. The silty soil of the surface layer has higher mechanical strength, and the thick layer of silt can be used as the bearing layer of the pile-in type drilling platform; the silt and the silty clay belong to the soft soil and can not meet the pile-in type drilling platform The fine sand, silt and the thickness of the river and lake facies are generally more than 10m. It is the ideal holding platform for the pile-type drilling platform in this area. The general form and characteristics of the base soil failure in the base area are analyzed, and the damage of the foundation soil during the process of the pile-shoe type drilling platform is analyzed. The process of the plug-in pile is the dynamic penetration process, the soil body around the pile end and the pile shoe is strongly disturbed, the damage of the foundation soil is mainly caused by the impact and shear, and no obvious continuous sliding surface appears in the soil, and the process and the soil body in the static state of the soil are damaged as a whole. Based on the analysis of the damage form of the soil in the process of inserting the pile, according to the limit equilibrium theory, the method of the failure surface is assumed, and the plug-in resistance based on the passive earth pressure in the uniform and double-layer foundation soil is derived. The calculation of the ultimate bearing capacity is based on the overall shear failure mode of the soil, and the soil mass is given. In this paper, the calculation formula of the pile-in pile in the soil and the double-layer foundation soil is derived, and the shear-shear failure mode of the soil is established. There is a certain gap between the resistance of the inserted pile and the actual pile-in resistance, and the plug-in pile is given separately. The upper limit and the lower limit of the resistance are calculated. In the process of pile resistance analysis, it is assumed that the failure surface is closer to the failure mode of the soil in the process of inserting the pile, and the calculation results of the example also show that the pile resistance calculated by the method is more than that of the previous limit bearing capacity. It is close to the actual pile-in resistance, and enriches the pile-shoe type drilling platform. According to the survey data of the well pad after the plug-in pile, the change characteristics of the foundation soil after the process of inserting and pulling the pile are analyzed, and the pile-pile depth prediction method is discussed. The strength recovery mechanism of the soil in the pit. After the foundation soil is subjected to the process of plugging and pulling the pile, a pile pit of a certain size and depth is formed on the sea floor, The pile pit is gradually razed under the action of the surface of the formation in the acoustic recording of the shallow formation. The pile pits that have not yet been flattened are in the sonar image. The results show that the water content in the pile cavity is less than the water content outside the pile and the water content of the foundation soil under the pile is less than that of the pile. and the compressive modulus of the soft clay is generally smaller than the compressive modulus of the ground soil outside the pile, and the compressive modulus of the soft clay is generally smaller than that of the pile, The compressive modulus of the foundation soil at the periphery of the pit is studied. The research is that the silt is the main bearing stratum of the research area pile shoe type drilling platform, and has good drainage conditions, and the strength of the silt in the pile pit after the extraction and removal of the pile is generally Greater than or near the strength of the surrounding soil. The soft clay is in the process of pile-in due to poor drainage conditions It is disturbed by the disturbance, and the intensity is reduced. The soil strength recovery process of the disturbed foundation is complicated, and the influencing factors mainly have the effect of re-excitation and the compression and solid of the soil. In order to improve the strength of the foundation soil, pre-pressing can be adopted to improve the strength of the foundation soil. The bearing capacity of the foundation soil is improved. In recent years, with the development of the offshore oil, the operation of the platform plug-in pile in the research area is frequent, and the foundation soil is disturbed and destroyed, so that the foundation soil can be complex The formation condition of the well pad becomes more complicated. Although the strength of the foundation soil can be restored under the action of the ocean water, the construction of the post-platform plug-in pile due to the difference in the strength of the soil and the strength of the surrounding soil There is a great potential safety hazard in the operation process. The change of the engineering property and the shadow of the platform plug-in by the disturbance are further studied.
【學(xué)位授予單位】：中國海洋大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2014
【分類號】：TU473.1
【引證文獻(xiàn)】
相關(guān)碩士學(xué)位論文 前1條
1 馬彬彬;暴風(fēng)浪作用下海底粉土液化研究[D];國家海洋局第一海洋研究所;2015年
本文編號：2507110
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