考虑软土层参数变化时震陷量的计算  

Seismic subsidence estimation under parameter variation of muddy soil

作　　者：刘金韬[1] 

机构地区：[1]水利部水利水电规划设计总院,北京100120

出　　处：《地球物理学进展》2014年第1期412-417,共6页Progress in Geophysics

摘　　要：软土层在发生震陷过程中，厚度和孔隙比随着震动的持续会不断变化，每一次加荷后，软土层都会因为压缩而厚度减小，相应孔隙比也会减小；而且震陷量的大小与软土层的排水条件也有着密切的关系，在考虑软土层参数变化及上下相邻土层的排水条件后，利用震动固结原理，提出了震陷量的计算方法，并利用该方法对唐山沿海地区的软土层在1976年地震中的震陷量进行了计算，结果表明震陷量Ⅶ度区在27．4～111mn2之间，Ⅷ度区在114～67mm之间，Ⅸ度区在463～1315mm之间．据震后实测的地面垂直形变资料显示，沿海地区地面沉陷量Ⅶ度区一般在25～100mm之间，Ⅷ度区一般在100～500mm之间，Ⅸ度区一般在500～1551mm之间．结果表明，计算结果与实测结果大致吻合．The seismic subsidence hazards are very serious where earthquake occurred frequently. The seismic subsidence of silt soft soil is a hazard of them. The silt soft soil is widely dispersed over the coast. Tangshan earthquake In 1976 brings up the seismic subsidence in the wide coastal region. Observation in this region shows that the seismic subsidence capacity of silt soft soil is between 25 mm to 100 mm in the area of 7-level seismic intensity, 100 mm to 500 mm in the area of 8- level seismic intensity, and 500 mm to 1551 mm in the area of 9-1evel seismic intensity. The silt soft soil has some harmful characteristics for engineering, e.g. big water content, big void ratio, high compressibility, high sensitivity, low strength, poor water permeability and easy creep etc. Especially, its thixotropy, which means the strength of silt soft soil is getting lower under the vibrating load, the seismic subsidence is a sort of expression of thixotropy as well. When the silt soft soil is vibrated, the water of soil is squeezed out and the silt soft soil is compressed. The thickness and void ratio will be changed continually with vibration when the silt soft soil is in seismic subsidence. The earthquake force is a cyclical reciprocating loads. The thickness of silt soft soil will be decreased in compression and result in the decrease of void ratio after every loading. The seismic subsidence of silt soft soil has close relationship with drainage condition also. Based on principle of vibration consolidation, this paper put forward the method of seismic subsidence estimation considering parameter variation of silt soft soil and drainage condition of adjacent soil layer. Furthermore, the seismic subsidence of silt soft soil in Tangshan coastland was estimated using this method and the result shows that calculated values of 27. 4 mm to 111 mm in the area of 7-level seismic intensity, 114 mm to 671 mm in 8- level area of the seismic intensity, and 463 mm to 1315 mm in the area of 9-level seismic intensity.

关 键 词：震动固结 震陷 超静孔压 地震加速度 软土 

分 类 号：P315[天文地球—地震学]