振动沉管碎石桩地基加固工程

通过详细分析某工程的地质情况，提出了用振动沉管碎石桩处理该区液化地基的方法，对处理后的结果通过标准贯入试验技术进行了分析，证明该法能很好地解决该区液化地基问题。     

地震区液化地基处理技术

本文就液化地基处理的方法进行了归纳分析，总结出地震区液化地基处理的一般方法，最后对北京顺化培训中心主楼地基处理提出意见。     

跟管夯扩桩法加固地基和处理可液化地基土层的效果分析

通过具体工程实践,阐述了跟管夯扩桩法进行地基加固算是砂土液化的工艺特点,使用多种试验方法分析和评价了处理液化地基土层的效果。     

振冲碎石桩处理液化地基的设计与施工

介绍采用振冲碎石桩处理液化地基并提高地基承载力的工程实例，对有关地基处理设计和施工工艺参数的确定进行了分析和探讨。     

干振碎石桩法处理可液化地基的探讨

根据高速公路工程液化地基加固试验研究,对干振碎石桩加固液化地基的原理、设计和施工参数进行了探讨,通过地基处理前后桩间土物理力学性质、标准贯入试验、静力触弹试验等测试结果的对比分析,表明干振碎石桩用于处理液化地基具有较大的优越性,值得推广应用。     

刚性基础和柔性基础下公路地基液化比较研究

对刚性基础和柔性基础下公路地基抗液化能力的变化状况进行了研究，并对地基液化指数进行了探讨，根据研究结果给出了考虑公路路基影响的地基液化处理方案。     

沉管干振碎石桩加固液化地基试验研究

本文根据现场液化地基加固试验研究，对沉管干振碎石桩加固液化地基的原理、效果、质量控制方法进行了讨论。研究成果表明，沉管干振碎石桩用于处理液化地基具有较大的优越性。瞬态瑞利波法具有快捷可靠的优点，可以在地基处理质量检测中推广使用。     

振冲置换法处理衡运大厦液化地基

结合工程实例,按照《建筑抗震设计规范》(GB50011—2001),较为详细地分析了饱和地基在地震时产生液化的原因、地基土地震液化的判别、液化指数的计算、液化等级的划分、地基液化的处理方法和振冲置换法的设计。用载荷试验方法对单桩允许承载力进行了检测和沉降观测,采用静力触探和标准贯入对碎石桩处理液化土层的效果进行了检验。结果表明,采用振冲置换处理饱和地基,改善原地基土的力学性质,液化地基处理效果良好,提高了地基土的整体承载力,减少了沉降量。     

碎石桩处理液化地基效果检测分析

采用碎石桩法处理液化地基土,对处理后的地基土进行了检测分析。采用重型动力触探试验(DPT)检测了桩身密实度和桩长,采用室内土工试验方法检测桩间土粘粒含量及桩体材料,利用标准贯入试验(SPT)检测桩间土的加固效果,并确定液化是否被消除,采用静力平板载荷试验(PLT)检测其处理后的复合地基土承载力是否满足设计要求。通过对检测结果的综合分析可知,碎石桩法可以处理液化地基土。本文可为其他相似工程设计、施工和检测提供参考。     

填石强夯处理软弱粉土地基试验研究

某机场主跑道场地为大面积冲海积粉土、砂土 ，浅层地基土强度低，浅部地层在7度地震烈度条件下可发生液化，液化程度轻微－中等。为论证地基处理方案，采用了多种方法进行地基处理试验，填石强夯试验是其中试验方法之一，试验分Hol、Ho2和Ho3三个区，分别采用不同的夯击能或填石方法进行。经现场效果检测表明：填石强夯 处理粉土软弱地基，可取得良好的处理效果，提高了地基土的强度，消除了土层液化可能性。该方法处理大面积软弱粉土地基具有设备简单、施工方便、经济易行和效果显著的优点。     

浅析液化土地基的判别与处理方法

简单介绍了液化土地基的几种判别方法,对我国有代表性的几种液化判别方法及改进的IRN模型的地基液化判别法进行了简单评述,最后介绍了液化地基的处理方法,可为工程技术人员在实际判别和处理液化土地基时提供一些帮助。     

不同规范对饱和砂土液化判别的差异及影响分析

现执行的规范对采用标准贯入试验判别饱和砂土液化的应用条件有不同的要求,通过分析应用条件不同,对液化评价的影响,指出若采用场地整平标高作为场地液化计算的起始标高,对实测的标贯击数尚需进行校正,而粘粒含量宜以实际粘粒含量进行液化判别标贯击数临界值的计算。     

Dynamic behavior of liquefiable ground reinforced by in-situ cement-mixing lattice wall

In-situ cement-mixing lattice-shaped ground improvement (lattice wall) is one of the effective countermeasures for liquefiable grounds. However, its high cost hinders its wide applicability. This is mainly due to the conventional concept of seismic designs which do not allow any liquefaction of the ground against earthquakes.The recent seismic design code was revised to comply with the concept of performance-based design, which allows some displacement or slight damage to structures, such as pile foundations, during major earthquakes. In order to apply lattice walls to meet the concept of the recent design standard, especially against major earthquakes, it is necessary to establish a rational design method that considers the quantitative effect of lattice walls.In this study, therefore, a series of 1-g field shaking table tests was performed with a lattice wall, and the effect of the wall was carefully evaluated through the quantitative measurement of the stress–strain relationship of the liquefiable ground inside the lattice wall and in the free ground (without a lattice wall). It became possible to quantitatively examine the effect of the wall by installing small accelerometers into the ground with precision.Two major positive effects of the lattice wall were observed through the series of shaking table tests. One was the delay in the onset of liquefaction by the restriction of shear strain, and the other was the recovery of the shear stiffness of the ground even after the onset of liquefaction. These experimental results indicate that lattice walls can be applied as an effective liquefaction countermeasure method, especially when the performance-based design is applied to address large earthquakes.     

饱和砂土场地大型爆炸液化现场试验研究

土体振动液化是岩土工程领域中引人注目的热点问题,振动及液化引发的房屋倒塌或堤坝溃决将严重危及生命和财产安全。基于室外大型爆炸液化可控试验场地,开展了一系列饱和砂土中的单点及多点微差爆炸液化试验。介绍了现场爆炸液化试验的主要技术细节,包括钻孔及布药方式、监测设备及方法、混凝土结构及土质堤坝的设计等。分析了饱和砂土中单点和多点微差爆炸引起的土中孔隙水压力上升规律、爆炸液化的影响因素以及利用多点微差爆炸液化人工制造大面积液化试验场地的实现条件和方法,并最终开展爆炸液化场地混凝土结构及土质堤坝的变形研究。试验的成功实施为人工制造大型振动液化试验场地的方法提供了参考。     

Influence of inherent anisotropy on the seismic behavior of liquefiable sandy level ground

Inherent anisotropy is a crucial aspect to consider for an improved understanding of the strength and deformation characteristics of granular materials. It has been the focus of intense investigation since the mid-1960s. However, inherent anisotropy’s influence on ground seismic responses, such as liquefaction, has not been extensively studied. In this paper, inherent anisotropy’s influence on ground seismic responses is examined through a series of dynamic centrifuge model tests on liquefiable level sand deposits. During the model setup, five different deposition angles (0, 30, 45, 60, and 90 degrees) were achieved using a specially designed rigid container. The models were exposed to tapered sinusoidal input accelerations and the recorded results were fully investigated. It was found that deposition angle-caused inherent anisotropy significantly influenced the excess pore pressure responses during the shaking and dissipation phases. The amount of excess pore pressure build-up and the high excess pore pressure duration increased with the deposition angle, while the dissipation rate decreased as the deposition angle increased. The inherent anisotropy also influenced liquefaction-induced ground settlement, with volumetric strain increasing along with the deposition angle. With respect to response acceleration, inherent anisotropy’s effects depended on the amount of excess pore pressure build-up (i.e., degree of liquefaction). In view of these results, it was concluded that a sandy ground, deposited at a higher angle (i.e., closer to 90 degrees), is more susceptible to liquefaction and that inherent anisotropy’s influence should be considered when evaluating the liquefaction potential and performing effective stress analyses.     

饱和砂土的剪切波速与抗液化强度相关性研究

依据扭剪振动原理,开发出剪切波速与振动三轴联合试验装置。进而针对取自20 多个工程场地、埋深在20 m 以内的12种大量原状砂土,分析了同一类土、在同一固结压力作用下,原状与重塑土样抗液化强度与其初始剪切波速之间的相关性。结果表明,当判别液化的应变标准不超过6%时,土的抗液化强度与其初始剪切波速之间存在良好的对应关系。当应变破坏标准超过6%,土的初始剪切波速与抗液化强度之间不具备唯一对应关系。     

强夯黄土地基抗液化性状的试验研究

通过野外剪切波速测试、室内动三轴试验和微结构扫描对强夯黄土地基进行了对比分析。结果表明 ,强夯有利于提高黄土地基的抗液化性能 ,但不能完全消除黄土地基的液化 ,对黄土地区的强夯施工作业提供了有益的参考     

Liquefaction potential at Izmit Bay: comparison of predicted and observed soil liquefaction during the Kocaeli earthquake

The 1999 Kocaeli earthquake resulted in large-scale damage to structures and a death toll of more than 20,000. Numerous liquefaction and associated ground deformations caused by the earthquake were particularly observed along the southern coasts of Izmit Bay and Sapanca Lake, as well as the city of Adapazari. The paper discusses the soil liquefaction and lateral spreading along the southern coast of Izmit Bay. A microzonation map was created using the data from liquefaction susceptibility analyses and a liquefaction severity index. The predicted liquefiable zones showed good agreement with site observations. The assessment suggests that the amount of liquefaction-susceptible layers in the soil profile reduces away from the coastal zone.      

关于改进中国规范中土液化判别准则的建议

基于BP网络的人工神经元模型和可靠度理论,建立极限状态的抗液化阻力比函数和液化概率函数。沿用原抗震规范中液化标准贯入锤击数基准值概念,建立了简化的液化判别概率方法。该法以液化标准贯入锤击数作为估计液化势的基本依据。基准值是给定地面加速度、土层埋深、地下水位的液化临界锤数,也与震级大小和液化概率有关。为了对不同震级和土层中任一点进行液化判别,引入土层埋深水位以及震级大小对基准值的修正系数。为了方便工程应用,也给出了按地震分组的液化判别方法。     

碎石回填土下液化砂层的强夯试验研究

针对某沿海下卧地震液化夹层的碎石回填土地基,开展了不同能量级的强夯试验。通过采用平板载荷试验、孔隙水压力测试、地面振动测试、室内土工试验等多种方法和手段,对比分析了强夯前后地基土工程性质的变化,评价了强夯产生的振动对地基土液化的影响以及对周围环境的影响,对下卧地震液化夹层的碎石回填地基强夯加固效果做出了评价。为同类复杂地质条件下不同夯击能的强夯地基处理提供了翔实的经验数据和参考依据。