离心机振动台模型试验验证的珊瑚礁砂液化判别方法研究  

A liquefaction evaluation method for coral sand based on dynamical centrifuge model test verification

作　　者：梁小丛[1,2] 陈平山 刘志军[1,2] 王永志 朱明星 LIANG Xiao-cong;CHEN Ping-shan;LIU ZHI-jun;WANG Yong-zhi;ZHU Ming-xing(CCCC Fourth Harbor Engineering Institute Co.,Ltd.,Guangzhou,Guangdong 510230,China;Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai),Zhuhai,Guangdong 519082,China;Key Laboratory of Earthquake Engineering and Engineering Vibration,Institute of Engineering Mechanics,China Earthquake Administration,Harbin,Heilongjiang 150080,China)

机构地区：[1]中交四航工程研究院有限公司,广东广州510230 [2]南方海洋科学与工程广东省实验室(珠海),广东珠海519082 [3]中国地震局工程力学研究所地震工程与工程振动重点实验室,黑龙江哈尔滨150080

出　　处：《岩土力学》2023年第11期3173-3181,3212,共10页Rock and Soil Mechanics

基　　金：国家自然科学基金项目(No.42377150)。

摘　　要：工程现场珊瑚礁砂场地主要以珊瑚砂、砾组成的宽级配珊瑚礁砂,其砾粒含量分布从20%~90%,其液化特性与普通石英砂有较大区别,如仍采用现行液化判别方法评估珊瑚礁砂场地液化潜势,则容易导致工程场地的抗液化处理设计不经济或无法满足要求。以中国南海岛礁和东帝汶珊瑚礁砂为研究对象开展了原级配大动三轴试验分析,建立了基于抗液化强度(cyclic resistance ratios,简称CRR)与相对密实度Dr关系液化判别方法,并通过离心机振动试验进行对比分析。结果表明,当采取相同地震动工况时,由动三轴试验产生的超孔压比相比模型试验超孔压比大;当持时增加到30周时(对应震级8级),土体液化深度达20m,有效证明了珊瑚礁砂场地遭遇强地震动时具有液化潜在风险。此外,通过液化判别计算,验证了基于CRR-Dr关系的液化判别方法准确率达82.5%,且判别不一致工况的判别结果偏保守,进一步验证了此方法可应用于工程抗液化设计。The coral sand in the project site is mainly composed of coral sand and gravel with wide gradation characteristics,and its coral gravel content is distributed from 20%to 90%.Its liquefaction characteristics are quite different from quartz sand.The application of the current liquefaction evaluation method to the coral reef sand site will lead to the design of liquefaction remediation being uneconomical or unacceptable.In this study,the sands from islands and reefs of the South China Sea and the coral reefs of East Timor were taken as the research objects to conduct the original gradation dynamic triaxial test.A liquefaction evaluation method was developed based on the relationship between the liquefaction resistance CRR and the relative density Dr,and a comparative analysis was carried out through the centrifuge vibration test.The results show that under the same ground motion conditions,the excess pore pressure ratio generated by the dynamic triaxial test is larger than that of the model test;when the duration increases to 30 weeks(corresponding to magnitude 8),the soil liquefaction depth is up to 20 m,which effectively proves that the coral reef sand site has the potential risk of liquefaction under the action of strong earthquakes.In addition,through the calculation of liquefaction discrimination,it is verified that the accuracy rate of the liquefaction evaluation method based on the“CRR-Dr”relationship is 82.5%,and the inconsistent results are conservative for the working conditions,which can be applied to engineering liquefaction mitigation design.

关 键 词：珊瑚礁砂 液化判别方法 离心机振动台模型试验 强地震动 

分 类 号：TU435[建筑科学—岩土工程]