岩石力学与工程学报
巖石力學與工程學報
암석역학여공정학보
CHINESE JOURNAL OF ROCK MECHANICS AND ENGINEERING
2009年
z2期
4046-4053
,共8页
吕西林%任红梅%李培振%彭功生
呂西林%任紅梅%李培振%彭功生
려서림%임홍매%리배진%팽공생
土力学%液化%数值分析%孔隙水压力%地震响应
土力學%液化%數值分析%孔隙水壓力%地震響應
토역학%액화%수치분석%공극수압력%지진향응
soil mechanics%liquefaction%numerical analysis%pore water pressure%seismic response
应用有限差分法程序FLAC~(3D)对液化场地自由场体系的地震响应进行三维完全非线性分析.与通常采用的等效线性法相比,完全非线性分析方法由于采用了弹塑性模型,可以自动计算永久变形;采用合理的塑性方程,使得塑性应变增量与应力相联系;结合孔隙水压力模型可以模拟地震作用引起的饱和砂土液化问题.计算模型考虑了土体非线性、孔隙水压力的变化以及模型边界条件的处理等.通过与液化场地自由场体系振动台试验结果的对比分析,方法的有效性得到验证.结果表明,砂土对地震动可起滤波和隔震作用;当加速度峰值到达时砂土层中的孔隙水压力比存在负值;震后土中孔隙水压力不一定随振动的停止而立即开始消散,短期内也可能继续增长.
應用有限差分法程序FLAC~(3D)對液化場地自由場體繫的地震響應進行三維完全非線性分析.與通常採用的等效線性法相比,完全非線性分析方法由于採用瞭彈塑性模型,可以自動計算永久變形;採用閤理的塑性方程,使得塑性應變增量與應力相聯繫;結閤孔隙水壓力模型可以模擬地震作用引起的飽和砂土液化問題.計算模型攷慮瞭土體非線性、孔隙水壓力的變化以及模型邊界條件的處理等.通過與液化場地自由場體繫振動檯試驗結果的對比分析,方法的有效性得到驗證.結果錶明,砂土對地震動可起濾波和隔震作用;噹加速度峰值到達時砂土層中的孔隙水壓力比存在負值;震後土中孔隙水壓力不一定隨振動的停止而立即開始消散,短期內也可能繼續增長.
응용유한차분법정서FLAC~(3D)대액화장지자유장체계적지진향응진행삼유완전비선성분석.여통상채용적등효선성법상비,완전비선성분석방법유우채용료탄소성모형,가이자동계산영구변형;채용합리적소성방정,사득소성응변증량여응력상련계;결합공극수압력모형가이모의지진작용인기적포화사토액화문제.계산모형고필료토체비선성、공극수압력적변화이급모형변계조건적처리등.통과여액화장지자유장체계진동태시험결과적대비분석,방법적유효성득도험증.결과표명,사토대지진동가기려파화격진작용;당가속도봉치도체시사토층중적공극수압력비존재부치;진후토중공극수압력불일정수진동적정지이립즉개시소산,단기내야가능계속증장.
3D fully nonlinear analysis of seismic response of free field in liquefiable site is carried out using the general finite difference program FLAC~(3D). Compared with the equivalent-linear method,the permanent and irreversible displacements can be modeled automatically in the fully nonlinear method. A proper plastic formulation is used in the soil nonlinear constitutive relation,whereby plastic strain increments are related to stresses. Combined with the pore water pressure model,soil liquefaction under the seismic excitation can be modeled. Soil nonlinearity,pore water pressure build-up process and boundary condition of the model are taken into account in the calculation model. A comparison between the results from the finite difference analysis and those from the shaking table tests is made to validate the effectiveness of the computational model. Numerical results demonstrate that the liquefied soil can filter and isolate vibration. The phenomena of transient minus pore pressure occurr in the test. Pore water pressure does not always dissipate in short time immediately after the excitations,but it may keep on increasing.