Investigations on deep vibratory compaction in sandy soils for desgin optimization and execution quality with respect to effectivity, simulation and control of the achieved soil densification

对沙土中的深度振动压实进行研究，以优化设计和执行质量，实现土壤致密化的有效性、模拟和控制

• 批准号: 341427400
• 负责人: Professor Dr.-Ing. Frank Rackwitz
• 金额: --
• 依托单位: Lehrstuhl für Bodenmechanik, Grundbau u Umweltgeotechnik
• 依托单位国家: 德国
• 项目类别: Research Grants (Transfer Project)
• 财政年份: 2017
• 资助国家: 德国
• 起止时间: 2016-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/341427400?language=en
• 关键词: Investigations; deep; vibratory; compaction; sandy

The scientific target of the envisaged project is the simulation of soil improvement by the deep vibro compaction method, whereby the design of this type of compaction requires the grid spacing of the densification points on the ground surface based on the density to be achieved, on the power and the diameter of the deep vibrator and on the granulometric soil properties. All these parameters have a significant influence on the densification results. The scientific methods and results of the research unit FOR 1136 will be used within this project although the main efforts within the FOR 1136 were concentrated on the vibro-installation of piles as a geotechnical construction process, which has been treated extensively.Within this envisaged transfer project for the engineering practice, the high cyclic accumulation model (HCA) will be used for the calculation of the deformation accumulation (volumetric as well as deviatoric) of the loose granular soil around the deep vibrator, wherein the extension of this HCA model for large strain amplitudes (in the range of a few percent of strain amplitude) has priority. It is well known that the existing HCA model can only be adapted for strain amplitudes in the per mille range. The numerical simulation of vibro compaction will be conducted on the one hand with the HCA model in a finite element formulation to determine the deformations within a large compactable area around the deep vibrator, whereby the hypoplastic model for the estimation of the deformation amplitudes as input to the HCA model for the entire field will be used. For the simulation of the multiphase medium (soil skeleton, water) the Multi-Material Arbitrary Lagrangian-Eulerian (MMALE) formulation is used to describe the interaction of the vibrator with the immediate fluidized soil close to the vibrator as well as the transition area in the soil between fluidized and compacted zone.Within the proposed project physical model testing of vibro compaction will be performed as a first step of validation of the simulation model. As a further validation step field experiments with the partner responsible for the application will be performed. These field tests will be conducted on selected construction sites of the industrial partner in order to verify the accuracy of the simulation and to validate an additional simplified model, which is aimed to be developed within this project. Finally, this simplified model should serve as an engineering model. It should be able to indicate the required distance between the densification points as well as the accessible final density after the deep compaction as a function of granulometry of the soil and the pre-existing bulk density as well as the power of the used deep vibrator.

设想项目的科学目标是模拟深层振动压实法的土壤改良，这种类型的压实的设计需要基于要达到的密度、深层振动器的功率和直径以及土壤颗粒特性的地面上的压实点的网格间距。所有这些参数都对致密化结果有显著影响。本项目将采用FOR 1136研究单位的科学方法和成果，尽管FOR 1136的主要工作集中在作为岩土工程施工过程的桩的振动安装上，该过程已得到广泛处理。在本工程实践的设想转移项目中，高周反复累积模型（HCA）将用于变形累积的计算（体积和偏差）的松散粒状土壤周围的深振动器，其中该HCA模型对于大应变幅度（在应变幅度的百分之几的范围内）的扩展具有优先权。众所周知，现有的HCA模型只能适用于千分之一范围内的应变幅。振动压实的数值模拟将一方面与有限元公式中的HCA模型一起进行，以确定深层振动器周围的大范围内的变形，从而将使用亚塑性模型来估计变形幅度，作为整个领域的HCA模型的输入。对于多相介质的模拟（土壤骨架，多物质任意拉格朗日-欧拉（MMALE）公式用于描述振动器与振动器附近的直接流化土壤以及土壤中流化区和压实区之间的过渡区的相互作用。在拟建项目中，振动压实的物理模型试验将作为验证公式的第一步进行。仿真模型作为进一步的验证步骤，将与负责应用的合作伙伴进行实地实验。这些现场测试将在工业合作伙伴的选定建筑工地进行，以验证模拟的准确性，并验证旨在在本项目中开发的附加简化模型。最后，这个简化模型应该作为一个工程模型。它应能够显示压实点之间的所需距离以及深层压实后可达到的最终密度，作为土壤粒度测定和预先存在的体积密度以及所用深层振动器功率的函数。