Experimental study on mitigation of damage induced by lateral displacement of liquefied subsoil

减轻液化地基侧向位移损伤的试验研究

基本信息

批准号：
10555160
负责人：
TOWHATA Ikuo
金额：
$ 6.91万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

项目摘要

The present study aims at developing a mitigation measure by which liquefaction-induced deformation of embankment is reduced to an acceptable magnitude. This measure is intended to be practiced in such a situation as densification and other prevention of liquefaction are not feasible. Shaking table tests were conducted on models of embankment resting on liquefiable sandy deposit. Firstly, two rows of sheet pile walls were installed at the foot of the embankment so that lateral spread of foundation sand might be mitigated by the stiffness of sheet pile walls. Although this idea worked well when the frequency of shaking was high, still there observed certain extent of subsidence in the embankment due to minor amount of boiling sand near the wall as well as consolidation settlement of foundation sand.Low frequency shaking demonstrated the problem of sheet pile wall measure. Since the displacement of wall was large, cracks opened near the wall and a large amount of sand boiled out from there, leading to significant subsidence of the embankment. This problem was overcome by placing additional berm above the walls in order to prevent boiling. This idea was shown to be satisfactory in a shaking table test. Special sheet pile walls were attempted which had drainage capability. When the drainage was attached beneath the slope of embankment, pore pressure was reduced near the surface and a rigid soil block was formed therein.This soil block prevented the aforementioned boiling of sand and reduced subsidence. On the contray, sheet pile walls installed from the top of an embankment with tie-rod connection at the top did not worked well because the unprotected slope failed and consequently the sheet pile walls distorted substantially.

本研究旨在制定一种缓解措施，通过该方法将液化诱导的路堤变形降低至可接受的幅度。该措施旨在在密度化和其他预防液化的情况下实践。摇晃桌子测试是对基于液化的沙质沉积物的路堤模型进行的。首先，在路堤的脚下安装了两排薄桩墙，以便通过板桩壁的刚度减轻粉底砂的侧向散布。尽管当摇动的频率很高时，这个想法效果很好，但由于墙壁附近少量的沸腾沙子以及基础沙子的固结沉降，仍观察到路堤中某些程度的沉降。桩墙测量。由于壁的位移很大，因此在墙壁附近打开裂缝，并从那里煮沸了大量沙子，从而导致路堤的显着沉降。通过在墙壁上方放置额外的护堤以防止沸腾来克服这个问题。在摇桌测试中，这个想法被证明是令人满意的。尝试了具有排水能力的特殊薄板墙。当将排水装置在路堤的斜坡下方时，在表面附近降低了孔隙压力，并在其中形成了刚性的土壤块。该土壤阻止了上述沙子的沸腾，并减少了沉降。在con绕的情况下，从顶层的路堤顶部安装的板桩墙在顶部的连接效果不佳，因为未受保护的斜坡失败，因此板桩壁严重扭曲了。