The influence of pile-driving induced vibrations on the hydration ofearly-age concrete regarding cast-in-place concrete pile groups

打桩诱发振动对现浇混凝土群桩早龄期混凝土水化的影响

• 批准号: 496855719
• 负责人: Professor Dr.-Ing. Sascha Henke
• 金额: --
• 依托单位: Professur für Konstruktionswerkstoffe und Bauwerkserhaltung
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/496855719?language=en
• 关键词: influence; pile; driving; induced; vibrations

Cast-in-place concrete piles are the typical solution for foundations in non-load bearing soil. In addition, groups of cast-in-place piles are possible in cases where high load concentrations are expected. However, is the distance between the piles in such a group too close, the pile driving induced vibrations in the subsoil due to the installation process of the latest pile could impair the hydration process of the previously prepared piles. Thus, the concrete strength development of the early-age concrete is affected. Potential pile defects could lead to serious consequences, especially considering that visual inspection of any pile deficiency is impossible. The soil dynamic system behind this situation is very complex: (i) source (driving pile); (ii) medium (soil with anelastic wave propagation in the near and far field), (iii) receiver (adjacent pile with fresh or early-age concrete exposed to vibrations). In the past, these complex dependencies had not undergone adequate scientific investigation. The objective of the research proposal is to develop a model that combines the geotechnical wave propagation models with the concrete models from material science in order to enable quality assurance during the production process of cast-in-place concrete pile groups. To achieve this objective, the working program covers in-situ field investigation, numerical simulations as well as experimental lab work. The field investigations aim to describe the system under realistic conditions and to identify the input parameters for the numerical simulations as well as the settings for the experimental tests. Based on the validated numerical model from the field investigation further numerical simulations study the effect of different parameters involved, e.g. driving energy, soil conditions, geometric aspects, etc. In associated laboratory investigations fresh and early-age concrete are exposed to vibrations to mimic the on-site conditions and to study the effect of vibrations on the later concrete resistance and durability parameters. Finally, the compilation of the geotechnical and material results shall lead to an engineering model that enables a scientifically proven design and production of cast-in-place concrete group piles. One outcome of the engineering model could be nomograms to prevent concrete damage during the production process by indication of adequate concrete level of maturity before starting the driving process of the adjacent pile under consideration of the soil condition, driving energy, pile distance, etc.

现浇混凝土桩是非承重土壤中基础的典型解决方案。此外，在预计荷载集中度较高的情况下，可采用成组灌注桩。然而，如果这样一组桩之间的距离太近，由于最新桩的安装过程，打桩引起的底土振动可能会损害先前准备的桩的水化过程。因此，影响了早期混凝土的强度发展。潜在的桩缺陷可能导致严重后果，特别是考虑到任何桩缺陷的目视检查是不可能的。这种情况背后的土壤动力系统非常复杂：（i）源（打桩）;（ii）介质（近场和远场具有滞弹性波传播的土壤）;（iii）接收器（暴露于振动的新混凝土或早期混凝土的相邻桩）。在过去，这些复杂的依赖关系没有经过充分的科学调查。研究建议的目的是开发一种模型，将岩土波传播模型与材料科学的混凝土模型相结合，以便在现浇混凝土桩群的生产过程中保证质量。为了实现这一目标，工作计划包括现场调查，数值模拟以及实验室工作。现场调查的目的是在现实条件下描述系统，并确定输入参数的数值模拟以及实验测试的设置。基于验证的数值模型，从现场调查进一步的数值模拟研究所涉及的不同参数的影响，例如，驱动能量，土壤条件，几何方面，在相关的实验室调查新鲜和早期混凝土暴露于振动，以模仿现场条件，并研究振动对后期混凝土的阻力和耐久性参数的影响。最后，岩土工程和材料结果的汇编应形成工程模型，该模型可实现经科学验证的现浇混凝土群桩设计和生产。工程模型的一个结果可以是诺模图，以通过在考虑土壤条件、驱动能量、桩距离等的情况下在开始相邻桩的驱动过程之前指示足够的混凝土成熟度水平来防止生产过程期间的混凝土损坏。