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三峡库区周期性库水位变化对抗滑桩加固效果非饱和流固耦合分析 总被引:1,自引:0,他引:1
三峡库区内广泛发育的滑坡等地质灾害在水库运行水位周期性波动条件下会发生复活乃至失稳。抗滑桩是其中应用广泛、效果良好的防治措施之一。抗滑桩在库水位周期性波动条件下对滑坡的治理加固效果及其自身的变形受力特征是较为重要但研究尚少的问题。采用非饱和岩土本构关系,考虑在库水位周期性波动条件下滑坡体处于饱和-非饱和周期性变化时的流固耦合效应,采用有限元法对设置抗滑桩前后库区某滑坡的位移和稳定状态进行模拟,并分析了抗滑桩内力及其桩顶位移随库水位变化的特征。研究结果表明,抗滑桩对滑坡的水平位移控制效果较为显著,安全系数最少能提高到2以上。在库水位运行的一个周期内,抗滑桩加固滑坡的安全系数变化幅度不超过5.4 %,而抗滑桩内力及桩顶位移不超过10.4 %。滑坡最小安全系数和抗滑桩最大受力出现在最高水位时,其变化趋势与水位变化趋势较为一致。 相似文献
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结合某高速公路结构物基础混凝土灌注桩与强夯加固台后地基土层交叉施工所发生的工序性技术问题,推导了桩侧土受强夯振动作用时,土层传给桩身的横向与竖向振动力的大小和桩身位移计算的力学模型,并根据工程实例有关桩身物理力学指标和强夯施工夯击能等数据,采用该力学模型计算分析了夯点到桩的最小安全距离和夯击能大小与桩身位移的关系,通过工后桩身质量检测结果验证了力学模型的正确性。 相似文献
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Pile foundations are widely used to support offshore wind turbines due to their cost effectiveness and rapid constructions. Offshore piles must be designed with enough capacity to withstand overturning moments caused by wind turbines and other environmental factors such as wave excitations and extreme winds. In this study, a full-scale field experimental test is undertaken to determine the pile behaviour under various lateral loading conditions. A distributed fiber optic sensing technology is used to measure strains along two instrumented piles. The bending moments and lateral deflections are calculated from distributed fiber optic sensors, and then analysed with the various p-y methods. Field measurements indicated that for two offshore piles ZK01 and ZK28 with diameter of 2 m and length of 71.5 m and 77.5 m, the maximum lateral movements under a given lateral load of 800 kN were 369.1 mm and 351.7 mm, respectively. The maximum bending moment occurred at 6.5 m and 5.5 m below seabed level with the corresponding depth of 12.15D and 11.95D for pile ZK01 and ZK28, respectively. The position of “zero crossing” of soil resistance for two instrumented piles is almost the same, even though the piles have different lengths. The lateral deflections and bending moments of the two instrumented piles are predicted by the API and hyperbolic method, which indicates that the hyperbolic method yields larger prediction errors than the API method. A modified p-y approach is then proposed for more reliable predictions when compared with field measurements. 相似文献
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One of the major concern in the excavation in soft soil areas is the effect of soil movement on adjacent pile foundations. In this paper, three-dimensional finite element models are established to study the axial response of the adjacent pile foundations close to an excavation in soft soil. The results show that, due to the nearby excavation, the axial bearing capacity of a single pile under compression decreases about 13.6%, and considerable additional settlements of a single pile subjected to the working compression load are generated. Therefore, the characteristics of load transfer mechanism between pile shaft and around soil, as well as the tip soil reaction are investigated extensively, which demonstrates that, as expected, the nearby excavation leads to a reduction of ultimate soil friction resistance. Furtherly, the widely employed load transfer method for pile foundation is modified to consider the effects of nearby excavation, which can be employed to predict the axial response of an axially loaded pile foundation beside an excavation. © 2018, Editorial Office of "Modern Tunnelling Technology". All right reserved. 相似文献
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辽河大桥39#主塔桩基础为大直径深水超长群桩基础,对全部39根桩进行了桩底后压浆,有效地提高了桩基承载力和整体刚度,减少了基础的不均匀沉降.重点介绍大规模群桩基础通过桩底压浆提高承载力的机理、压浆工艺及压浆效果. 相似文献
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通过现场勘探分析了某部食堂桩基不均匀沉降产生的原因,结合实际情况提出了治理措施.事实表明,该措施无论治理效果还是经济性均很好,治理经验具有重要的工程实际指导意义. 相似文献
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低应变反射波法在青藏铁路基桩质量检测中的应用及分析 总被引:5,自引:0,他引:5
介绍低应变反射波法检测基桩完整性原理,通过对青藏铁路基桩质量检测,发现在高原冻土环境下,基桩的质量问题主要是扩颈。产生桩身扩颈的原因是:施工期进入6月以后,气温相对升高,冻土层在机械施工扰动下,破坏了原来冻土环境,造成冻土融化后形成扩孔。根据有关冻土资料表明,地基土的法向冻胀力取决于地基土的冻胀性,基础底板受法向冻胀力随基础埋深的增加而减小;切向冻胀力在桩身缺陷处,会产生应力集中,使桩身破坏。对于扩颈桩,由于扩颈处桩周侧面积增大而使切向冻胀力增大对桩产生不利影响。针对冻土区冻胀力对基桩的危害,提出了改善基桩施工质量的措施。 相似文献