近岸水平场地液化侧向大变形机理及软化模量分析方法   总被引：3，自引：1，他引：3  

蔡晓光  袁晓铭  刘汉龙  孙锐  周静 《地震工程与工程振动》2005,25(3):125-131

本文依据震害现象和实验探讨近岸水平场地地面液化侧向大变形机理，改进现有软化模量分析技术，给出一套地面液化侧向大变形的分析方法。近岸水平场地侧向大变形机理因地基中孔隙水压力升高、土体模量衰减、土骨架变软使偏应变得到充分发展所致，其水平永久侧移可用从底部到顶部呈增加形式的整体变形描述。利用本文方法，对1995年阪神地震中近岸沉箱岸壁和土体液化侧向大变形进行了数值模拟，结果与震后实测结果和试验结果在主要特征上一致，说明改进的软化模量法可以用于地面液化侧向大变形的分析。  相似文献   

Liquefaction evaluation discrepancies in tropical lagoonal soils     

Peter G. Nicholson 《Geotechnical and Geological Engineering》2006,24(5):1259-1269

Field penetration tests and shear wave velocity measurements are both established and accepted methods for evaluating liquefaction potential in soils. The results produced by the two methods are generally well correlated. However, recent studies have shown that when investigating tropical lagoonal deposits, the same accepted methods for evaluating liquefaction potential often produce significant discrepancies in results. This discrepancy is most apparent in saturated lagoonal deposits of calcareous gravelly sand (or sandy gravel), which tend to exhibit low penetration resistance values but relatively high shear wave velocities. These disparate test results can suggest different soil classifications under current building codes. Ambiguity in the code may allow for a potentially unconservative classification, which may in turn allow for the use and construction of less costly, lighter weight foundation systems than warranted. Equally as important, the potential for unconservative design as related to liquefaction appears to be high when shear wave velocity measurements are used as a basis for evaluation in these types of lagoonal deposits. Because of this, it is strongly recommended that caution should be excercised when determining seismic design parameters in these types of geologic environments. A hypothesis to explain the discrepancies in the results of evaluation methods and a suggested design protocol is proposed.  相似文献   

秦皇岛七里海潟湖水上钻探取样及勘察成果分析     

王建伟  霍玉兵  李晶 《探矿工程》2018,45(4):73-77

秦皇岛七里海湿地生态修复工程主要通过退养还湿、清淤疏浚和岸线综合整治对七里海潟湖进行生态修复和景观提升。通过水上钻探取样技术,对七里海潟湖进行工程勘察,根据土层物理力学性质,分析该区域工程地质特征、液化分区情况和浅层土类别,对工程疏浚适宜性作出评价,为清淤疏浚和岸线整治提供有利依据。  相似文献   

循环水压作用下粉土渗流试验研究     

张民生  王秀海  刘红军  臧文坤  翟桂林 《中国海洋大学学报(自然科学版)》2014,44(9):82-88

海底塌陷凹坑是黄河三角洲地区常见的一种地貌现象,广泛分布于近代沉积海床中。虽然目前海底塌陷凹坑形成机理尚未明确,但普遍认为其成因与波浪引起的海床渗流有关。为此,设计模拟波压力的实验装置,对粉土施加40kPa循环水压荷载,研究正常固结粉土在液化渗流条件下的侵蚀过程。试验过程中,粉土液化时产生2种不同的裂隙,即倾斜状的"干裂隙"和水平状的"水夹层";孔隙水从"水夹层"中渗出,把从土样侧壁冲刷下的物质运移至土样表面堆积,形成"泥火山"。试验表明,土体内气泡溢出对表层土的侵蚀具有强化作用;循环荷载产生的孔隙水压力梯度是粉土液化渗流动力,而渗流过程对土的粒径成分具有粗化作用;分析结果表明,波压力引起的海床渗流是长效的作用机制,不同于地震荷载引起的渗流侵蚀。这种侵蚀模式是海底塌陷凹坑形成的主要原因。  相似文献   

汶川地震中甘肃清水田川黄土液化的试验研究          下载免费PDF全文

王谦  王兰民  袁中夏  王平  丁风梅 《水文地质工程地质》2012,39(2):116-120

2008年5·12特大地震中,位于甘肃省清水县郭川乡的田川村发生了饱和黄土的液化滑移灾害。本文首先在对田川场地进行考察的基础上,综合田川在汶川地震中的震害情况以及滑移区的地形条件,将该地区在汶川地震中的烈度进行了修正。其次对田川黄土进行了物性指标测试以及室内动三轴液化试验,根据试验结果,综合考虑产生液化所需的场地及土性条件、黄土的动强度和液化特性,对田川黄土液化灾害进行了分析,并采用反应分析的方法对其进行了液化判定。研究结果证明了田川黄土液化的事实存在性,为低烈度区黄土液化提供了新的震害依据。

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波速扁铲侧胀试验（SDMT）在液化判别中的应用     

谢凯  朱定华 《岩土工程技术》2012,26(2):70-73

波速扁铲侧胀仪（SDMT）是由标准的扁铲侧胀仪（DMT）和测量剪切波速砜的地震测试模块组成。综合描述了SDMT试验方法,对SDMT和钻孔波速试验测出的剪切波速砜比较,以及SDMT的液化判别初步分析。SDMT在南京的测试应用证明了SDMT的可靠性。  相似文献   

http://www.sciencedirect.com/science/article/pii/S167498711100137X     

Amir Hossein Alavi  Amir Hossein Gandomi 《地学前缘(英文版)》2012,3(4):541-555

This study presents promising variants of genetic programming (GP),namely linear genetic programming (LGP) and multi expression programming (MEP) to evaluate the liquefaction resistance of sandy soils....  相似文献   

Parametric study of the wave-induced residual liquefaction around an embedded pipeline     

《Applied Ocean Research》2016

Wave-induced liquefaction in a porous seabed around submarine pipeline may cause catastrophic consequences such as large horizontal displacements of pipelines on the seabed, sinking or floatation of buried pipelines. Most previous studies in relation to the wave and seabed interactions with embedded pipeline dealt with the wave-induced instaneous seabed response and possible resulting momentary liquefaction (where the soil is liquefied instantaneously during the passage of a wave trough), using theory of poro-elasticity. Studies for the interactions between a buried pipeline and a soil undergoing build-up of pore pressure and residual liquefaction have been comparatively rare. In this paper, this complicated process was investigated by using a new developed integrated numerical model with RANS (Reynolds averaged Navier–Stokes) equations used for governing the incompressible flow in the wave field and Biot consolidation equations used for linking the solid–pore fluid interactions in a porous seabed with embedded pipeline. Regarding the wave-induced residual soil response, a two-dimensional poro-elastoplastic solution with the new definition of the source term was developed, where the pre-consolidation analysis of seabed foundation under gravitational forces including the body forces of a pipeline was incorporated. The proposed numerical model was verified with laboratory experiment to demonstrate its accuracy and effectiveness. The numerical results indicate that residual liquefaction is more likely to occur in the vicinity of the pipeline compared to that in the far-field. The inclusion of body forces of a pipeline in the pre-consolidation analysis of seabed foundation significantly affects the potential for residual liquefaction in the vicinity of the pipeline, especially for a shallow-embedded case. Parametric studies reveal that the gradients of maximum liquefaction depth with various wave and soil characteristics become steeper as pipeline burial depth decreases.  相似文献   

Mitigation of Soil Liquefaction Using Stone Columns: An Experimental Investigation     

Chunxia Huang  Zhilong Sui  Lei Wang  Kaifu Liu 《Marine Georesources & Geotechnology》2016,34(3):244-251

The risk of liquefaction and associated ground deformation may be reduced by using various ground-improvement methods, including the stone column technique. To examine the effects of stone columns, a shaking table experimental study using four models (two containing saturated sand and two containing stone column composite foundations) was conducted to measure the development and dissipation of excess pore water pressure and the acceleration response during a simulated earthquake. The test results demonstrate that the effectiveness of stone columns for mitigation of soil liquefaction during an earthquake depends on the following three aspects: (1) the densification of the surrounding soils; (2) drainage along the stone column; and (3) reduction in the total cyclic shear stress of the soil (because the cyclic shear stress is partially shared by the stone column). The first factor (the densification of the surrounding soils) is the most prominent factor among these three. The drainage and re-distribution of the shear stress can only develop fully for sand ground with a considerably higher density; thus, the effectiveness of the last two factors are only significant for dense sand ground.  相似文献   

SPT-CPT Correlation and Its Application for Liquefaction Evaluation in China     

Xueliang Zhao 《Marine Georesources & Geotechnology》2013,31(3):272-281

The standard penetration test (SPT) and cone penetration test (CPT) are the two most commonly used in-situ tests. In this paper, SPT-CPT correlation is investigated using statistical and regression method based on a database of in-situ tests. Two correlation equations of the SPT N-value and the CPT cone tip resistance q_c are proposed. The equations are applied for the liquefaction potential evaluation. Three effect factors including the soil type, mean particle size, and fine content are investigated for SPT-CPT correlation. The simple correlation can be used for the preliminary site investigation with least data and information. The comprehensive one can give more accurate result with detailed data. These two correlation equations are useful for different purposes with different accuracies. The liquefaction evaluations using the proposed correlation method are compared with those from the Chinese code method. It is shown that the proposed correlation can be helpful for site investigation and geotechnical design in practice.  相似文献