【作者】 刘爱民；

【导师】 闫澍旺；

【作者基本信息】 天津大学 ， 岩土工程， 2013， 博士

【摘要】 随着我国经济实力的增强和沿海岸线的开发，有大量的工程需要建设在潮差带浅海区域。受区域环境和地质条件的影响，我国的沿海地区大都是新近沉积的淤泥质粘土或淤泥，为港口工程建设带来了极大的困难。目前对水下软土地基多采用深层水泥搅拌法（CDM法）或砂桩法（SCP法）进行处理，费用高昂且需要一些大型的专用施工设备。而真空预压法是目前陆上软土地基加固的首选方法，预压荷载可一次快速施加地基不会失稳，同时也不需要堆载材料、避免了堆载材料的开采和运输，因此，研究真空预压技术在水下软基处理工程中的应用是非常有意义的。由于受到施工技术的限制，真空预压法的所有工序都在水下施工尚有一定的困难。做为水下真空预压技术的过渡阶段，充分利用潮差带区域涨落潮的环境特点，对真空预压工艺进行相应的改进，在潮差带区域成功进行了4项水下真空预压处理工程，形成了成套地基处理技术，取得了良好的效果。本课题研究的主要成果如下：（1）、潮差带区域水下真空预压技术同陆上真空联合堆载预压相比，其加固机理同非常相似，只是联合堆载荷载是一个变动水荷载。潮差带区域水下真空预压设计时，预压荷载可取膜下真空荷载与膜上平均水压荷载之和。膜上平均水压荷载可根据施工期间的潮水位和地面标高进行分析计算。（2）、通过对潮差带区域进行的4项水下真空预压处理工程进行总结，对铺设砂垫层技术、打设排水板技术、埋设密封膜技术等进行了相应的改进，形成了成套施工技术。（3）、针对水下监测的特点，开发了现场监测数据自动记录和传输技术，实现了地基监测数据的自动测量、自动采集、自动存储和自动传输功能。研究结果表明，水下真空预压技术可以在潮差带区域大量的工程建设中应用，起到节约工程造价和缩短工程工期的目的，其应用前景非常广阔。更多还原

【Abstract】 With the development of China economic strength and the exploration in coastal zones, more and more projects need to be constructed in intertidal zones in neritic area. However, under the influence of geological environments, recently deposited silty clay or silt is distributed in China costal area, posing great difficulties in construction of port engineering. Currently for improvement of underwater soft soil foundation, cement deep mixing method (CDM) or sand compaction pile method (SCP) are utilized, featured with high cost and need of large special construction equipment. Meanwhile, the vacuum preloading technique is the first choice for soft soil foundation improvement, featured with a quick preloading without instability of foundation, no need of surcharge and involved exploration and transportation. Therefore it is significant to research the application of vacuum preloading technique in improvement of underwater soft soil foundation.Due to the limitation of construction technologies, it is difficult to apply all the procedures of the vacuum preloading technique under water. As a transit stage of application of the vacuum preloading technique under water, we have improved the current vacuum preloading technique by considering the characteristics of the tidal environment of the intertidal zone. The improved vacuum preloading technique has been applied successfully in4projects in intertidal zone and produced good result. Based on these application, a full set of underwater soft soil foundation improvement technique by vacuum preloading has been formed with the following innovations:(1) The improvement mechanism of underwater soft soil foundation improvement technique by vacuum preloading is similar to that of conventional vacuum and surcharge combined preloading technique, featured with a variant hydraulic load. In the design, the preload can be assigned to be the sum of vacuum preload beneath the membrane and the average hydraulic load on the membrane, and the latter can be obtained from the tidal level and ground elevation.(2) By summarizing the experiences from4projects improved by underwater vacuum preloading technique, improvements were made on the conventional sand cushion construction, plastic vertical drain, laying-out of sealing membrane. So a full set of construction technique has been formed.(3) A series of automatic data recording and transmission techniques have been developed based on the characteristics of underwater monitoring. Therefore the automatic monitoring can be achieved by automatic measurement, data acquisition, storage and transmission.This research has showed that it is necessary to apply underwater vacuum preloading technique in more projects in intertidal zone in order to shorten construction period and save cost. So it is expected a wide application in engineering construction.更多还原