1989～2011期间8次强地震中抗液化地基处理成功案例的回顾与启示

回顾了1989年美国Mw6.9级Loma Prieta地震、1993年日本Ms7.8级Kushiro-Oki地震、1994年日本Mw8.2级Hokkaido Toho-Oki地震、1995年日本Ms7.2级阪神地震、1999年台湾集集地震、1999年土耳其Mw7.4级Kocaeli地震、2001年美国Mw6.8级Nisqually地震以及2011年Mw9.0级东日本地震中场地抗液化工程措施的成功案例,初步分析了各种抗液化工程措施的有效性与优劣性,可以给出如下工程场地抗液化处理的经验:(1)对于易液化的沿海及填海造陆场地,采用适宜的抗液化工程措施应成为地基处理不可缺少的环节;(2)应基于场地条件、经济条件及环境要求,综合考虑场地抗液化地基处理措施的选择;(3)挤密砂桩法和碎石桩法运用广泛、技术成熟且比较经济,宜优先选择作为抗震设防烈度Ⅷ度及以下地区的场地抗液化地基处理措施;(4)强夯法使用机具简单、费用低廉,适宜选择作为抗震设防烈度Ⅷ度及以下地区大面积场地的抗液化地基处理措施;(5)注浆法、深层搅拌法、旋喷法作为抗震设防烈度Ⅸ度及以下地区的场地抗液化地基处理措施是有效的;(6)多种抗液化地基处理措施联合使用的处理效果往往优于单一措施单独使用的处理效果,在条件许可的情况下,宜选择多种抗液化地基处理措施联合使用,以期达到更好的处理效果。

Review and implication of successful ground improvement cases about mitigating soil liquefaction induced by 8 strong earthquakes from 1989 to 2011

The successful cases about soil liquefaction mitigation are reviewed, in the sites of the 1989 Loma Prieta, USA earthquake, the 1993 Kushiro-Oki, Japan earthquake, the 1994 Hokkaido Toho-Oki, Japan earthquake, the 1995 Hanshin, Japan earthquake, the 1999 Chi-Chi, Taiwan earthquake, the 1999 Kocaeli, Turkey earthquake ,the 2001 Nisqually, USA earthquake and the 2011 great east Japan earthquake, and the applicability and performance of various mitigation measures are analyzed. The lessons we have learned from these successful cases of soil treatment include: (1) for bay areas or reclaimed lands, the ground treatments against soil liquefaction are indispensable; (2) the choice of soil liquefaction countermeasures should be based on the consideration of site conditions, economic conditions and the environmental conditions; (3) compacted sand piles and stone columns are widely used, which have become mature and economical technics, and they are suitable for improving liquefaction-prone soils in the seismic intensity VIII zone and below; (4) the dynamic compaction method is simple and less expansive, and this method is especially suitable for large fields in the seismic intensity VIII zone and below; (5) grouting, deep soil mixing and jet grouting methods are effective in mitigating the earthquake-induced liquefaction damages in the seismic intensity IX zone and below; 6) the combination of various liquefaction countermeasures is more effective than an individual measure. If possible, multiple methods should be used in combination to achieve better effects.