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分析蓄能器在双作用液压锤和单作用液压锤液压回路的功能和作用,建立双作用液压锤和单作用液压锤中高、低压的蓄能器设计基本方法与步骤,为开发液压锤产品提供理论基础。 相似文献
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在分析双作用液压锤和单作用液压锤油路系统基础上,总结双作用液压锤和单作用液压锤特点,设计出既能实现双作用方式下落又能进行单作用方式下落新型液压锤油路系统。 相似文献
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对一种液压锤的运动过程进行了运动学及动力学分析,在液压锤的建模中不仅考虑了前腔和后腔液压油的作用力,而且考虑了活塞与换向阀各自所受的黏性摩擦力与密封摩擦阻力,同时也考虑了高压系统中各个容腔之间液压油的泄漏等问题.根据建立的数学模型,对液压锤各部分进行了计算仿真和分析,有利于改善和优化液压锤的设计参数. 相似文献
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高频液压振动锤打桩有限元方法分析 总被引:1,自引:0,他引:1
高频液压振动锤的使用在国外已经很普遍了,在国内也慢慢的推广开来,但是对高频振动锤的沉桩理论的研究还是落后于其实际应用。以前的研究主要集中在试验方面,在此基于PLAXIS 8.2岩土工程分析软件的动力模块分析高频振动锤打桩相关问题,主要对沉桩的位移、振动沉桩的应力场、超孔隙水压力的分布做简要的动力分析。分析表明超孔隙水压力的产生对振动沉桩起到一个很重要的影响,特别是无粘性土层中,如果桩周土体能产生振动液化,那么就能加快沉桩速度,提高施工效率。 相似文献
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使用有限元-无限元耦合方式建立了预制桩沉桩施工的三维有限元模型,将这一模型用于沉桩全过程的模拟。通过沉桩模拟结果与实测数据的对比,验证了所建模型的正确性。结合上海地区地质条件,对比了锤击法和振动法两种沉桩方式引起的振动衰减特征,根据有限元分析结果提出了地面振动的衰减公式。基于已有振动安全控制标准,提出了普通民房的振动控制标准,评估了两种沉桩方式的振动影响范围。本文成果可以为类似条件下沉桩方式的选择提供一定的参考。 相似文献
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为确保预制管桩设计合理并提高施工质量,在对沉桩过程进行研究的基础上,介绍了模拟实际打桩过程时柴油锤的模型、重锤与桩冲击响应的数值模拟及模型实现的主要功能等,分析了打桩监控试验的目的意义。分析表明,在设计环节模拟实际打桩过程中桩-土-锤之间的相互作用,对选择的桩型和打桩系统进行可行性分析,初步确定设计方案,然后实施试打桩并进行打桩监控试验,验证和调整初步设计方案中的桩-土-锤参数,实现设计方案的优化是非常必要和可行的。 相似文献
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在黄淮流域地区,PHC管桩施工时,容易遇到土层密实桩身下部断桩的情况。究其原因,由于土体具有黏、干、硬的特点,桩内土芯不易上升,在锤击沉桩过程中桩内土芯不断地挤密,最终形成土塞效应,桩内土芯压应力无法释放挤压破坏桩壁,造成桩身在锤击的反复作用下发生断裂。在上述地层条件下,PHC管桩沉桩时采用桩尖加内环等措施,可有效降低桩内土体的挤压力,解决桩身严重破损的难题。 相似文献
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《Soils and Foundations》2019,59(6):1946-1959
The ability of hydraulic pile driving hammers to overcome energy losses during freefall enables a greater proportion of the impact energy to be transferred to the pile than is possible with diesel hammers. This percentage, termed the energy transfer ratio, is not routinely measured in practice however, and there is an element of uncertainty regarding appropriate energy transfer ratios to adopt in driveability analyses. In light of such uncertainties, the energy transfer ratios of four- and five-tonne hydraulic hammers were assessed during installation of driven cast-in-situ (DCIS) piles at several sites in the United Kingdom. The piling rigs were fitted with instrumentation enabling the hammer velocity (and hence kinetic energy) at impact to be inferred for each blow during installation, with the corresponding energy transferred to the closed-ended steel installation tube ascertained using a Pile Driving Analyzer. The results of the study showed that energy transfer ratios were strongly dependent on the hammer drop height, with transfer ratios of 90% and above only achievable for drop heights in excess of 50% of the maximum value. Driveability analyses using measured energy transfer ratios from the fieldwork, as well as the traditional method using an assumed energy transfer ratio which is independent of drop height, yielded good agreement with measured driving records at a clean sand site. In contrast, poorer predictions were apparent for both methods at another site, where the coarse-grained strata had higher fines contents and significant layering, with the traditional method (assumed energy transfer ratio) over-predicting the maximum transferred energy and concealing the influence of dynamic soil properties on driveability. The findings of the study would suggest that lower energy transfer ratios may need to be considered in driveability predictions for these pile types (i.e. steel or DCIS piles) if lower drop heights are used during driving. 相似文献