砂土地震液化会造成地基失效和结构受损,因此场地液化判别至关重要。国内外规范中的液化判别方法简单实用,但均存在局限性。为更准确、全面地进行场地液化判别,利用三维有限差分程序FLAC3D,结合孟加拉卡纳普里河底盾构隧道项目,对典型钻孔位置土层的抗震液化特性进行数值分析。利用FLAC3D中的FINN模块建立土层三维模型,在重力平衡和水压力平衡后施加合理的地震波,进行动力计算,计算模型每个单元在计算过程中的最大超孔压比,若最大超孔压比=1,则该位置土体发生液化;若最大超孔压比<1,则该位置土体不会液化。计算后,部分土体的最大超孔压比=1,其他范围土体的最大超孔压比均<1。研究表明该地区土层会发生地震液化,且不同位置处液化深度不同、液化范围也不同,该数值分析液化判别结果与规范法判别结果一致。
Abstract
Seismic liquefaction of sand will give rise to the failure of foundation and structural damage. Discriminating liquefaction of the construction site is of vital importance. Liquefaction discrimination methods in specifications in China and abroad are simple and practical, yet still of some limits. In this paper, we performed numerical analysis on the seismic liquefaction characteristics of typical borehole soil layer of a shield tunnel project in Kanapuri River of Bangladesh using the FINN module of FLAC3D. We applied a reasonable seismic wave after the balance of gravity and water pressure and calculated the maximum excessive pressure ratio of each unit in the calculation process. If the maximum excessive pore pressure ratio is equal to one, the soil is liquefied at this position; if the maximum excessive pore pressure ratio is less than one, the soil is not liquefied. Calculation result revealed that the maximum excessive pore pressure ratio of some parts of soil is equal to one and other parts less than one. The result indicated that seismic liquefaction occurs in the soil layer in this area, and the liquefaction range is different at different locations. The result is consistent with the discriminant results of specification methods.
关键词
隧道抗震 /
液化判别 /
FLAC3D /
FINN模块 /
超孔压比
Key words
anti-seismic safety of shield tunnel /
liquefaction discrimination /
FLAC3D /
FINN module /
excessive pore pressure ratio
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参考文献
[1] 刘 鹏, 丁文其, 杨 波. 深水超长沉管隧道接头及止水带地震响应[J]. 同济大学学报(自然科学版), 2013, 41(7): 984-988.
[2] 王 刚, 张建民. 地震液化问题研究进展[J]. 力学进展, 2007, 37(4): 575-589.
[3] 王军龙. 砂土液化等级预测的主成分-Logistic回归模型[J]. 长江科学院院报, 2015, 32(9): 134-139.
[4] 陈国兴, 金丹丹, 常向东, 等. 最近20年地震中场地液化现象的回顾与土体液化可能性的评价准则[J]. 岩土力学, 2013,34(10): 2737-2755.
[5] 王 亮, 薄景山, 李孝波, 等. 砂土液化判别方法研究若干进展[J]. 世界地震工程, 2017, 33(4): 141-150.
[6] 袁晓铭, 孙 锐. 我国规范液化分析方法的发展设想[J]. 岩土力学, 2011, 32(增刊2): 351-358.
[7] ISHAC M F, HEIDEBRECHT A C. Energy Dissipation and Seismic Liquefaction in Sands[J]. Earthquake Engineering and Structural Dynamics, 1982, 10(1): 59-68.
[8] SEED H B, IDRISS I M. Simplified Procedure for Evaluating Soil Liquefaction Potential[J]. Journal of the Soil Mechanics and Foundations Division, 1971, 97(9): 1249-1273.
[9] ROBERTSON P K. Comparing CPT and Vs Liquefaction Triggering Methods[J]. Journal of Geotechnical and Geoenvironmental Engineering, 2015, 141(9): 1-10.
[10]陈国兴, 孔梦云, 李小军, 等. 以标贯试验为依据的砂土液化确定性及概率判别法[J]. 岩土力学, 2015, 36(1): 9-27.
[11]勾丽杰, 刘家顺. RBF神经网络模型在砂土液化判别中的应用研究[J]. 长江科学院院报, 2013, 30(5): 76-81.
[12]曾凡振, 侯建国, 李 扬. 中美抗震规范地基土液化判别方法的比较研究[J]. 建筑结构学报, 2010, 30(增刊2): 309-314.
[13]YOUD T L, IDRISS I M. Liquefaction Resistance of Soils: Summary Report from the 1996 NCEER and 1998 NCEER/NSF Workshops on Evaluation of Liquefaction Resistance of Soils[J]. Journal of Geotechnical and Geoenvironmental Engineering, 2001, 127(10): 817-833.
[14]牛琪瑛, 刘建君, 刘少文, 等. 碎石桩与水泥土桩加固液化地基的数值模拟研究[J]. 岩土工程学报, 2011, 33(增刊1): 488-491.
[15]邹 炎, 景立平, 崔 杰, 等. 基于可液化场地地震反应数值模拟的影响因素分析[J]. 防灾减灾工程学报, 2015, 35(2): 242-248.
[16]陈小云, 吴红刚, 杨 涛. 高原地区路基地震液化数值模拟研究[J]. 地震工程学报, 2017, 39(4): 706-712.
[17]陈育民, 徐鼎平. FLAC/FLAC3D基础与工程实例[M]. 北京:中国水利水电出版社, 2013.
[18]张向东, 张 晋, 苏伟林. 基于PL-Finn模型的饱和砂土液化数值分析[J]. 辽宁工程技术大学学报(自然科学版), 2017, 36(7): 724-728.
[19]杨继红, 董金玉, 黄志全, 等. 夯扩挤密碎石桩加固液化砂土地基的动力数值分析[J]. 岩土力学, 2014, 35(增刊2): 593-599.
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