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调查发现在黄河和密西西比河水下三角洲的塌陷凹坑地貌中存在有块体,有研究表明此塌陷凹坑由波浪作用下海底土体的液化形成。液化土体中存在的块体,在运动中会对海底结构物产生强烈的冲击作用,并导致液化后的海底工程地质性质不均匀。海底液化的土体中块体存在及其原因尚未有研究解释。本文以粉质土铺设底床,进行了2次底床固结时间不同的波致液化的水槽试验。通过测试底床的贯入阻力和分析玻璃珠在液化土体中的沉降分布状态,认为土体固结时间长,形成结构性块体,是液化土体中存在块体的原因。 相似文献
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《中国海洋大学学报(自然科学版)》2021,51(8)
沉积物流是海底沉积物运移的重要载体,高速的沉积物流会冲击海底结构物并导致其损坏,其中拖曳力通常被认为是结构物破坏的主要因素,因此研究结构物在不同沉积物流流速下的拖曳力具有重要意义。本文采用可调坡度平直水槽对结构物进行冲击试验并对所配粘土组分的沉积物流进行流变测试,分析结果表明,当坡度一定时,存在一个临界沉积物流浓度,使沉积物流速度和结构物所受拖曳力达到最大值,本次试验条件下在0°、3°、6°、9°坡下,所得临界沉积物流浓度为560 g/L。同时,给出了在试验浓度范围内(280～700 g/L),对于纯粘土组分沉积物流速度较低(0.2～0.6 m/s)时,结构物所受拖曳力与沉积物流速度、密度三者之间的关系表达式。 相似文献
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针对胜利油田埕岛海域海床土体强度的非均匀性和可能引起的海底管线差异沉降破坏,提出1种海底管线差异沉降安全性分析方法.具体介绍差异沉降产生的原因,通过分析管线的受力状态,建立管线因差异沉降引起的附加应力的表达式.针对黄河水下三角洲埕岛油田常见的3种规格管线,建立不同土质条件下的管线附加应力表格,方便工程师查询.考虑附加应力和流体对管线的应力,与管线材料的允许应力比较,可以判断管线的安全性. 相似文献
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海底管道在油气工业中发挥着重要作用,为保障其安全运营必须定期进行检测掌握其在海底的状态。有的海底管道在铺设时为其安全考虑,在海底管道上方覆盖了抛石等硬质保护层,这样就导致在海底管道定期检测时一些检测仪器难以探测到硬质保护层下海底管道的位置和埋深,而浅地层剖面仪和磁力仪仍然可以不同程度地实现这种情况下的海底管道检测。文中对浅地层剖面仪和磁力仪的原理进行了介绍并对其在上覆抛石等硬质保护层海底管道检测中的应用进行了分析探讨。分析结果表明浅地层剖面仪和磁力仪组成的综合检测系统对上覆硬质保护层的海底管道探测有一定效果,可查明海硬质保护层下海底管道的位置和埋深,为海底管道的安全管理和维护提供数据支持,也可为其他类似海底管道检测提供参考。 相似文献
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以黄河口海底粉土为研究对象,利用自行研发的监测设备现场监测了波浪作用下海底粉土的孔隙水压力响应过程,获取了2个大风过程中孔隙水压力的有效数据。波浪作用下海底粉土的孔隙水压力响应由表层土最先开始,向下层土延伸,且响应程度随着土层深度的增加而减弱。孔隙水压力响应特征受潮位与波高影响明显,潮位影响孔隙水压力响应的整体趋势而波高影响孔隙水压力响应的幅值,且海底粉土孔隙水压力对波高的响应具有滞后性,滞后时间约为2 h。大风过程中海底面以下1.5 m以深孔隙水压力未发现明显变化,说明其超过了波浪最大作用深度;海底面以下0.5 m位置处孔隙水压力在一段时间内产生剧烈振荡,无明显的累积现象,说明其处于波浪作用范围内,但波浪作用导致的孔隙水压力小于土体孔隙水压力的消散速率。 相似文献
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以黄河口海底粉土为研究对象,利用自行研发的监测设备现场监测了波浪作用下海底粉土的孔隙水压力响应过程,获取了2个大风过程中孔隙水压力的有效数据。波浪作用下海底粉土的孔隙水压力响应由表层土最先开始,向下层土延伸,且响应程度随着土层深度的增加而减弱。孔隙水压力响应特征受潮位与波高影响明显,潮位影响孔隙水压力响应的整体趋势而波高影响孔隙水压力响应的幅值,且海底粉土孔隙水压力对波高的响应具有滞后性,滞后时间约为2 h。大风过程中海底面以下1.5 m以深孔隙水压力未发现明显变化,说明其超过了波浪最大作用深度;海底面以下0.5 m位置处孔隙水压力在一段时间内产生剧烈振荡,无明显的累积现象,说明其处于波浪作用范围内,但波浪作用导致的孔隙水压力小于土体孔隙水压力的消散速率。 相似文献
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沉管在海底的位置靠露在水上的测量棱镜塔目标位置反求,为及时知道水下对接数据,调整施工,要求计算机实时通讯,同步观测棱镜目标,实时显示水底管段的位置特征。结合嘉兴电厂海底隧道工程,介绍了沉管隧道对接的测量理论和实施措施。 相似文献
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During the construction process of Qingdao Jiaozhou Bay Undersea Tunnel, the faults and other unfavorable geological discontinuities were often encountered. To study the water inrush mechanism in the faults, both physical model test and numerical analysis were carried out. The results of crown displacement and hydraulic pressure of the monitoring sections in the physical model and numerical model were analyzed in this paper. It was found that the displacement and hydraulic pressure in the process of tunnel construction are often interacted as both cause and effect, and the lower of hydraulic pressure is often accompanied with the growth of its displacement. The changing of the excavation disturbed zone during the excavation in the undersea tunnel was also studied. The results show that the excavation disturbed zone in fault is larger than that in surrounding rock mass, and the excavation disturbance effects in the filling type fault are both transient and persistent. When the displacement and hydraulic pressure in the undersea tunnel change sharply during excavation, there are relatively slow and continuous change trend of the displacement and hydraulic pressure. For practical purposes, to prevent water inrush in the undersea tunnel, more attentions should also be paid to the undersea tunnel after excavation. 相似文献
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A laboratory study of local scour at complex piers under steady clear-water conditions is presented. The term complex piers is used to define a bridge pier comprising of a column, pile cap, and pile group. Comprehensive data over the full range of possible pile cap elevations for complex piers with different geometries were obtained using five complex pier models, which were scaled down from existing bridges in Malaysia. The data are used to evaluate existing methodologies for characterizing the effective width of complex piers with varying pile cap location relative to the undisturbed streambed. The effect of pile cap location on scour depth is also addressed. To improve the predictions of local scour at complex piers, the new data and some previous data are used to propose a new method to predict local scour depth at complex piers. 相似文献
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This communication is dedicated to the investigation history and naming of the undersea morphostructures of the Sea of Japan for the last 50 years. Many of them were first described and studied during long-term geological-geophysical investigations in this basin carried out by Russian scientists. The analysis of 60 names of its undersea feature names revealed that only approximately half of them are cited in the GEBCO Gazetteer some of the undersea morphostructures are known under two or more names, the origin of their names is unknown, or their names were chosen voluntarily. For maintaining the priority of Russian investigations, the nomenclature and names of the undersea features should be adjusted in accordance with the national and international principles and regulations. 相似文献
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The necessity and the preliminary tentative plan for the construction of the undersea tunnel across Taiwan Strait are expounded in this atricle. The strait undersea tunnels, which have been built and investigated in the world, and their engineering characteristics and construction methods have been introduced herein briefly. Taiwan has been a part of China since ancient times and the people between the mainland and Taiwan are kindred compatriots in the extended family of the Chinese multinational country. For a long time, the people between southeast of China and Taiwan have had frequent communication in economy and culture. With the progress of times and the need of development, it has been put forward to build a safe and reliable undersea tunnel that is not affected by the environment across Taiwan Strait, and one which is also a magnificent project for the China in the long-term. Whether by using a bridge or an undersea tunnel or both across the strait is a problem worthy of further research. According to such conditions as the weather of Taiwan Strait, depth of water, undersea terrain, possibility of engineering and hydrological geology under the sea, as well as the possibility of Taiwan Strait as a main shipping passage from south to north of China and the experience of existing passage across strait in the world, the primary analysis shows that the scheme of an undersea tunnel should be considered. Therefore the concept of the undersea tunnel engineering across Taiwan Strait is introduced in detail here. 相似文献
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The necessity and the preliminary tentative plan for the construction of the undersea tunnel across Taiwan Strait are expounded in this atricle. The strait undersea tunnels, which have been built and investigated in the world, and their engineering characteristics and construction methods have been introduced herein briefly.?Taiwan has been a part of China since ancient times and the people between the mainland and Taiwan are kindred compatriots in the extended family of the Chinese multinational country. For a long time, the people between southeast of China and Taiwan have had frequent communication in economy and culture. With the progress of times and the need of development, it has been put forward to build a safe and reliable undersea tunnel that is not affected by the environment across Taiwan Strait, and one which is also a magnificent project for the China in the long-term.?Whether by using a bridge or an undersea tunnel or both across the strait is a problem worthy of further research. According to such conditions as the weather of Taiwan Strait, depth of water, undersea terrain, possibility of engineering and hydrological geology under the sea, as well as the possibility of Taiwan Strait as a main shipping passage from south to north of China and the experience of existing passage across strait in the world, the primary analysis shows that the scheme of an undersea tunnel should be considered. Therefore the concept of the undersea tunnel engineering across Taiwan Strait is introduced in detail here. 相似文献
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As a kind of transportation mode for crossing channels,undersea tunnel has incomparable advantages for its directness,convenience,fastness,insusceptibility to weather conditions,and smaller influences on environments.In recent years,with the development of undersea tunnel construction,the design and construction technologies have been greatly enhanced.The first undersea tunnel in China has just been built.Waterproofing is the key technique of undersea tunneling.A new concept of waterproofing scheme of grouting,sealing,draining and divided sections was adopted in the construction of the tunnel based on the researches,the in-situ geological features,the astuteness of the current technology,and the cost of construction.The structural details of the sealing and draining system are introduced to illustrate the salient features of the new waterproofing technique.It is hoped that experiences described in the paper can offer guidance for the construction of the extensive undersea tunnels in the coming years. 相似文献