STATE-OF-THE-ART APPLICATION OF THE LOG-PILING METHOD IN THE ROLE OF SHALLOW GROUND IMPROVEMENT FOR LIQUEFACTION MITIGATION

<p>This research paper focuses on evaluating the log piling technique as a sustainable, cost-effective, and environmentally friendly solution for reducing soil liquefaction risks during earthquakes. Although this method has been used extensively in Japan, mainly aiming for complete soil layer penetration, its economic viability is questionable in cases requiring very deep soil improvements. The study highlights that shallow ground improvement can notably enhance the seismic behavior of the soil-improvement-structure system, as evidenced by the reduced total and penetration settlements caused by liquefaction. The paper presents a methodology for determining the optimal dimensions of the modified ground zone using both small and medium-scale 1-g shaking table tests.&nbsp;</p> <p>The small-scale tests involve a detailed parametric study, examining variables like improvement width, pile spacing, and the depth-to-thickness ratio of the improved layer. Medium-scale tests, on the other hand, are geared towards identifying the minimum effective pile length. This approach provides a practical guideline for engineers to implement log piling for small residential buildings. Additionally, the paper utilizes finite element method (FEM) effective stress analysis, incorporating a PLAXIS 2D-based constitutive model (PM4Sand) calibrated with laboratory undrained cyclic torsional tests. This model accounts for the changes in effective stress during seismic activities. Finally, the study correlates its numerical findings with the results from the 1-g shaking table experiments, offering a well-rounded perspective on the effectiveness of log piling in mitigating liquefaction risks during seismic events</p> <p>&nbsp;</p>

这篇研究论文重点评估了木桩法作为一种可持续、具有成本效益且环保的解决方案，用于降低地震期间土壤液化风险。尽管这种方法在日本已被广泛使用，主要目的是完全穿透土层，但在需要对非常深的土壤进行改良的情况下，其经济可行性存疑。研究强调，浅层地基改良能够显著提高土壤 - 改良 - 结构系统的抗震性能，液化导致的总沉降和贯入沉降减少就证明了这一点。本文提出了一种利用小型和中型1 - g振动台试验确定改良地基区域最佳尺寸的方法。 小型试验包括一项详细的参数研究，考察改良宽度、桩间距以及改良层的深 - 厚比等变量。另一方面，中型试验旨在确定最小有效桩长。这种方法为工程师在小型住宅建筑中实施木桩法提供了实用指南。此外，本文利用有限元法（FEM）有效应力分析，结合基于PLAXIS 2D的本构模型（PM4Sand），该模型通过实验室不排水循环扭转试验进行了校准。这个模型考虑了地震活动期间有效应力的变化。最后，研究将其数值结果与1 - g振动台实验的结果相关联，为木桩法在减轻地震事件中液化风险的有效性提供了全面的视角。