2nd Ishihara Lecture: SPT- and CPT-based relationships for the residual shear strength of liquefied soils     

《Soil Dynamics and Earthquake Engineering》2015

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Liquefaction countermeasures by shallow ground improvement for houses and their cost analysis     

《Soil Dynamics and Earthquake Engineering》2015

A large number of houses suffered from liquefaction-induced damages in recent large earthquakes due to lack of economical countermeasures. In this study, the shallow ground improvement, up to several meters deep, was proposed as an economical liquefaction countermeasure for houses. Based on the case studies, the design criteria of allowable tilt angles and penetration settlements of houses were proposed for the required level of serviceability against moderate and large earthquakes. The results of questionnaire survey, airborne LiDAR survey and centrifuge model tests demonstrated that even a few meters of non-liquefiable layers in shallow ground could greatly reduce settlements and tilting of houses. A series of numerical analyses indicated that non-liquefiable layer of three meters thick below ground water table improved by solidification methods can prevent significant damages of houses. Furthermore, cost analyses were carried out for different ground improvement methods for both new and existing houses.  相似文献   

循环荷载下液化对土层水平往返变形的影响   总被引：3，自引：0，他引：3       下载免费PDF全文

孙锐  袁晓铭  李雨润  曹振中  陈龙伟 《地震工程学报》2009,31(1):8-14

采用多工况振动台实验研究液化对土层水平往返变形的影响.以干砂实验为参照,分析孔压增长与土层加速度和土层往返变形之间的关系.结果表明:液化将引起土表加速度显著降低,减小惯性力传递,但同时会引起土层往返剪应变明显增大.对往返变形而言,液化土层往返剪应变就可达到1%～5%的大变形状态,且液化土层往返剪应变沿深度呈下大上小分布.土层中孔压比0.4～0.8是往返变形出现放大的敏感段,在孔压比0.8左右而不是在1.0达到最大.作为其结果,土层液化将对刚性上部结构振动起减震作用,但同时增大的往返剪应变也易导致基础和地下结构破坏,特别是对液化层与下部非液化层交界处的构件更敏感.  相似文献   

A neurofuzzy system to analyze liquefaction-induced lateral spread     

S.R. García  M.P. Romo  E. Botero   《Soil Dynamics and Earthquake Engineering》2008,28(3):169-180

Lateral spreads of liquefied granular soil masses have caused severe damages to many engineered structures. Accordingly, many empirical procedures have been developed from field-direct observations and from multiple regression analyses carried out on the database gathered from many case histories. The intricacy and nonlinearity of the underlying phenomena makes the above approaches somewhat unreliable for estimating liquefaction-induced lateral spreads. The database has inconsistencies and contradictions because of inevitable subjective interpretations and neural network approaches have been proposed for dealing with these.To overcome these difficulties in this paper a hybrid system named neurofuzzy, which profits from fuzzy and neural paradigms, is advanced. The resulting model called NEFLAS (NEuroFuzzy estimation of liquefaction induced LAteral Spread) is shown to yield a much improved forecasting than both multiple regression and neural network procedures. The corresponding software can be obtained from the first author.  相似文献   

砂土地震液化的神经网络预测   总被引：4，自引：0，他引：4       下载免费PDF全文

陈奎  刘兴昌 《地震工程学报》2000,22(2):167-171

BP网络具有很强的非线性映射和自适应学习功能 ,可用于模式识别和预测评估等领域 .在简要分析BP算法的基础上 ,选取砂土的平均粒径 (d5 0 /mm)、相对密度(Dr/% )、标准贯入击数 (N63 .5 /击 )、上覆有效压力 (σv/kPa)、地震烈度 (I0 )作为指标 ,应用BP神经网络的理论与方法 ,预测砂土在地震作用下液化的可能性 ,取得了较好的预测效果 .说明将BP网络用于沙土液化预测是可行的 .  相似文献   

Practical applications of a nonlinear approach to analysis of earthquake-induced liquefaction and deformation of earth structures   总被引：2，自引：0，他引：2  

Zhi-Liang Wang  Faiz I. Makdisi  John Egan 《Soil Dynamics and Earthquake Engineering》2006,26(2-4):231-252

Seismic stability, liquefaction, and deformation of earth structures are critical issues in geotechnical earthquake engineering practice. At present, the equivalent linear approach is considered the ‘state of practice’ in common use. More recently, dynamic analyses incorporating nonlinear, effective-stress-based soil models have been used more frequently in engineering applications. This paper describes a bounding surface hypoplasticity model for sand [Wang ZL. Bounding surface hypoplasticity model for granular soils and its applications. PhD Dissertation for the University of California at Davis, U.M.I. Dissertation Information Service, Order No. 9110679; 1990; Wang ZL, Dafalias YF, Shen CK. Bounding surface hypoplasticity model for sand. ASCE, J Eng Mech 1990;116(5):983–1001; Wang ZL, Makdisi FI. Implementing a bounding surface hypoplasticity model for sand into the FLAC program. In: Proceedings of the international symposium on numerical modeling in geomechanics. Minnesota, USA; 1999. p. 483–90] incorporated into a two-dimensional finite difference analysis program [Itasca Consulting Group, Inc. FLAC (Fast Lagrangian Analysis of Continua), Version 4. Minneapolis, MN; 2000] to perform nonlinear, effective-stress analyses of soil structures. The soil properties needed to support such analyses are generally similar to those currently used for equivalent linear and approximate effective-stress analyses. The advantages of using a nonlinear approach are illustrated by comparison with results from the equivalent linear approach for a rockfill dam. The earthquake performance of a waterfront slope and an earth dam were evaluated to demonstrate the model's ability to simulate pore-pressure generation and liquefaction in cohesionless soils.  相似文献   

A semi‐empirical method for the liquefaction analysis of offshore foundations     

H. A. Taiebat  J. P. Carter 《国际地质力学数值与分析法杂志》2000,24(13):991-1011

This paper presents a relatively simple method for three‐dimensional liquefaction analysis of granular soil under offshore foundations. In this method, the Mohr–Coulomb model, which defines the elasto–plastic stress–strain relationship under monotonic loading, is modified to accommodate the plastic strains generated by cyclic loading. The effects of cyclic loading, evaluated from the results of laboratory tests on saturated samples of soil, are incorporated into the model. The method is implemented in an efficient finite element program for analyses of three‐dimensional consolidating soil. The practicability of the model is demonstrated by analysis of a typical offshore foundation, and the predictions of the numerical analysis are compared with the observed behaviour of the foundation. Copyright © 2000 John Wiley & Sons, Ltd.  相似文献   

区域土壤地震液化预测简化方法          下载免费PDF全文

李程程  李兆焱  袁晓铭 《地球物理学报》2020,63(5):2084-2095

利用可大范围获取的空间参数给出区域土壤液化的评估方法,可预估震前各地区土壤液化可能性,可快速评估震后震区土壤液化情况,对预防减轻地震灾害以及地震快速响应救援都具有重要意义的.本文以我国1976唐山大地震液化调查资料为背景,提出了区域土壤液化预测的四参数简化评估方法,并用2011年新西兰基督城地震进行了检验.选取场地平均剪切波速V s30、复合地形指数CTI、场地到河流的距离DR以及地面峰值加速度PGA,分别代表土壤密实程度、饱水状态、地质年代和遭遇的地震作用大小,并基于我国唐山地震液化区域调查资料生成的样本,运用经典二元Logistic回归方法,建立了区域土壤液化预测模型和评估公式,回归检验结果良好,整体回判成功率为77%,非液化和液化区域成功率分别为73%和78%.将公式应用于评估2011年新西兰基督城地震液化情况,区域液化和非液化成功率分别为82%和88%,总体成功率为84%.以上结果表明本文模型可靠,方法正确,可用于区域土壤液化震前预估以及土壤液化震后快速评估.  相似文献   

堵江滑坡作坝主要是工程地质问题及实例     

符文熹  万宗礼 《地质灾害与环境保护》1999,10(1):52-56

国内外大量的文献资料和作者的野外现场调查表明,滑坡堵江成坝形成堰塞湖在山区一带广泛发育研究发现堵江滑坡作坝存在的地质问题,主要包括坝体的渗透变形、稳定性、沉降及不均匀沉降和砂土液化问题。对上术叶质问题进行探讨,并对堵江滑坡坝进行实例分析,对开发利用滑坡堵江形成堰寒湖藏的丰富水能资源具有指导作用。  相似文献   

Floods on Mars released from groundwater by impact   总被引：1，自引：0，他引：1  

Chi-yuen Wang  Alex Wong 《Icarus》2005,175(2):551-555

On Earth, large earthquakes commonly cause saturated soils to liquefy and streamflow to increase. We suggest that meteoritic impacts on Mars may have repeatedly caused similar liquefaction to enable violent eruption of groundwater. The amount of erupted water may be comparable to that required to produce catastrophic floods and to form outflow channels.  相似文献