摘要
基于ABAQUS有限元软件平台,应用流固耦合两相介质动力模型孔压单元模拟场地饱和土体,进行了饱和土体-地下结构地震反应的计算研究。结果表明:在地震输入的最后时刻结构的两侧底角区域应力值最大;土体的孔隙压力和竖向位移主要集中在结构下方的区域,结构两侧土体的孔压与竖向位移呈对称分布;场地土体的竖向位移随深度的增加逐渐减小;体系最大地震反应出现的时刻对应于输入地震动的最大加速度出现的时刻。表明了流固耦合两相介质动力模型孔压单元在饱和土体-地下结构体系地震反应研究中的有效性。
In China, various transportation facilities have been built on a large scale. Sea-crossing tunnel projects are constructed in many coastal cities, and many underground structures are built on the soft soil foundation in the south region. These are all underground structures on saturated soil, and China lies in the Pacific Ring of Fire, with many cities located in the high-intensity earthquake zone, so the seismic security of underground structures such as tunnels and subway stations is an important subject. The key is to make an accurate calculation of the dynamic re- sponse of the underground structure to the earthquake load. The dynamic response of an under- ground structure in a saturated soil site is very different from that in other types of soil sites. Therefore, the seismic response of underground structure in the saturated soil should be studied with the right calculation model and analyzing method. At present, one widely used method is numerical simulation and calculation. Depending on the soil calculation model it employs, the analytic method can be classified into three types： the total stress method, simplified effective stress method, and fluid-solid coupling dynamic model method. The fluid-solid coupling model, which takes into account the coupling of fluid-solid dynamic response, is a theoretically complete calculation model. Therefore, the method based on the fluid-solid coupling dynamic model is theoretically sound and more accurate. In general, the dynamic response of an underground structure in a saturated soil site needs further study. In this paper, the seismic response of an underground structure in saturated soil is studied based on the fluid-solid coupling dynamic model and ABAQUS in order to get a complete view of the character- istics and rules of the seismic response. We conduct a simulated calculation of the seismic response of an underground structure in saturated soil, with the site soil simulated by the pore pressure element deduced from the fluid- solid coupling dynamic model of fluid-saturated porous media. The example chooses the seismic record of the N--S components of the Ninghe earthquake {magnitude 6.9 aftershock of the Tang- shan earthquake） as the seismic input. From the calculation, we obtain the distribution chart of soil pore pressure, vertical displacement of soil-tunnel system, and yon Mises stress on the struc- ture. The calculation results illustrate that by the end of the seismic input, the stress distribution is symmetrical. The stress distribution concentrates in the base area of the two sides, and the wa- ter pressure mainly distributes in the base and side areas. The pore pressure and vertical displace- ment of the site soil are maximal in the base area and decrease gradually in the side area. With in- crease of depth, the vertical displacement of the site soil decreases gradually. The pore pressure and vertical displacement of the site soil distribute symmetrically. The greatest seismic response occurs when the acceleration of the input earthquake wave reaches the maximum. The calculation results also indicate that the pore pressure element deduced from the fluidvso＇lid coupling dynamic model of the fluid-saturated porous model can be employed as an effective calculation model for the study of all types of underground structures in saturated soil sites.
出处
《地震工程学报》
CSCD
北大核心
2014年第2期228-232,共5页
China Earthquake Engineering Journal
基金
国家自然科学基金面上项目(51178011)
国家重点基础研究发展计划973计划项目(2011CB013602)
2011年度北京市属高校人才强教深化计划中青年骨干人才项目(PHR20110808)
关键词
饱和土体-地下结构
地震反应
流固耦合两相介质动力模型
孔压单元
saturated soil-underground structure
seismic response
dynamic model of fluid-solidcoupling media~ pore pressure element
