拉林铁路沿线风积沙自由场及其加固地基动力特性分析  

Dynamic Characteristics Analysis on Free Field and its Reinforced Foundation of Aeolian Sand along Lhasa-Nyingchi Railway

作　　者：薛春晓 XUE Chunxiao(Northwest Research Institute Co.,Ltd.of China Railway Engineering Corporation,Lanzhou 730000,China)

机构地区：[1]中铁西北科学研究院有限公司,兰州730000

出　　处：《铁道标准设计》2024年第3期49-55,共7页Railway Standard Design

基　　金：中国中铁股份有限公司重点科研项目(2018-重点-45);中铁科学研究院有限公司科研项目(中铁科研院(科研)字2018-KJ008-Z008-XB)。

摘　　要：拉林铁路沿线风积沙地基液化是其面临的主要问题之一,利用振冲碎石桩法进行地基处理时存在局部沉降量大等一系列问题。为解决上述问题,借助振动台试验,分析了研究区风积沙自由场和水泥搅拌桩加固地基的动力响应特征。研究结果表明,当地震强度较小时(0.1g),地震动在风积沙自由场中有较为明显的自下而上不断放大的趋势,当地震强度较大时(0.3g),地震动在土层中从下而上呈现先增大后减小的趋势;风积沙自由场中的液化现象并非同时发生,而是具有明显的时间差,即从上到下逐渐发展;输入的地震动强度一定时,风积沙自由场表层沉降量和孔压比较加固地基明显偏大,前者的地表宏观反应也明显强于后者,这表明水泥搅拌桩对风积沙地基的液化具有较好的抑制作用,这种抑制作用与地震动强度呈负相关,但与土层的埋深呈正相关。该研究成果可为风积沙地基的液化处理提供借鉴和参考。Liquefaction foundation of aeolian sand is one of the primary problems along Lhasa-Nyingchi Railway,and a series of problems are found such as large local settlement where vibroflotation gravel pile method is used for foundation treatment.To solve the above problems,the dynamic response characteristics on free field and cement mixing pile reinforced foundation in aeolian sand in the study area are analyzed using shaking table test.The results show that the ground motion in the free field of aeolian sand has an obvious increasing trend from bottom to top as the earthquake intensity is relatively small(0.1g),and it increases first and then decreases in the soil layer from bottom to top as the earthquake intensity is relatively large(0.3g).The liquefaction phenomenon in the free field of aeolian sand does not occur simultaneously,but has obvious time difference,i.e.,it develops gradually from top to bottom.When the input ground motion intensity is constant,the surface subsidence and pore pressure ratio on free field of aeolian sand are significantly greater than that of cement mixing pile reinforcing foundation,and surface macroscopic response of the former is much stronger than the latter,implying that the cement mixing pile has a good inhibition effect on the liquefaction of aeolian sand foundation.The inhibition effect is negatively correlated with the ground motion intensity,but positively correlated with the buried depth of soil layer.The research results can provide reference for the liquefaction treatment of aeolian sand foundation.

关 键 词：拉林铁路 风积沙 地基液化 水泥搅拌桩 振动台试验 

分 类 号：U211.9[交通运输工程—道路与铁道工程]