Ground improvement technique for sustainable infrastructure

可持续基础设施的地面改良技术

• 批准号: RGPIN-2019-05475
• 负责人: Hanna, Adel
• 金额: $ 1.89万
• 依托单位: Concordia University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=714865
• 关键词: Ground; improvement; technique; sustainable; infrastructure

Flexible foundations used for roads, railway tracks, pipelines, and earth dams are often built on soft cohesive soil. These structures usually suffer from low bearing capacity and excessive settlement, which are manifested in the form of sinkholes in roads and catastrophic collapses of the infrastructure and loss of life. Stone columns are known as cost-effective, environmentally friendly, easy to install and sustainable soil improvement technique for these types of structures (Wood et al., 2000; Hanna et al., 2013). Stone columns also provide additional drainage path, which will speed up the consolidation process, and accordingly the ground will resistance earthquakes (Sivakumar et al., 2004). Moreover, stone columns are used to improve the stability of natural slopes and to reduce liquefaction potential when installed in loose cohesionless soil (Etezad et al., 2015). The objective of the proposed research is to examine the performance of a flexible foundation overlying a group of stone columns. In order to achieve these objectives, experimental, numerical and analytical models will be developed to simulate the soil-structure-interaction of the problem stated. Experimentally: Laboratory prototype set-up consists of a testing tank, loading frame and measuring devices. The clay sample will be formed from a dry kaolin powder, mixed with water at about 60% saturation. Core samples of 100mm diameter of the reinforced clay will be extracted from the tank and placed in the triaxial set-up for testing. A consolidated undrained (CU) test will be carried out under cell pressure following ASTM, (2004). Reading of measuring devices will be recorded at a regular interval by data acquisition system (DAS), which will be attached to a personal computer. Numerically: High fidelity 3-D numerical models will be developed to examine the synergistic effect of the parameters govern the performance of this system. Three models will be developed to simulate the installation process of the stone columns in the soft soil and the second is to simulate the (CU) triaxial tests. The stresses and deformations measured from the first model will be used as an input data in the second model. The results of the second model will be validated with the results of the present experimental investigation. The third model is to simulate a flexible footing on a soft clay layer reinforced by stone columns. Analytically: The deduced failure mechanism from the present experimental and numerical investigations will be idealized and divided into slices of soft clay and sand, making the columns, a non-circular slip surface will be analyzed using Morgenstern-Price method of slice for non-circular slip surfaces, and the limit equilibrium technique. The results of this model will be used as the base to develop design theories to predict the bearing capacity of the system and to recommend on the number and spacing of the columns for economical design.

用于道路、铁轨、管道和土坝的柔性基础通常建在软粘性土壤上。这些结构通常承载能力低和过度沉降，表现为道路塌陷、基础设施灾难性倒塌和人员伤亡。石柱被认为是此类结构的经济高效、环保、易于安装和可持续的土壤改良技术（Wood 等人，2000 年；Hanna 等人，2013 年）。石柱还提供了额外的排水路径，这将加速固结过程，从而使地面能够抵抗地震（Sivakumar et al., 2004）。此外，石柱用于提高天然斜坡的稳定性，并在安装在松散无粘性土壤中时减少液化潜力（Etezad 等，2015）。 拟议研究的目的是检查一组石柱上的柔性基础的性能。为了实现这些目标，将开发实验、数值和分析模型来模拟所述问题的土壤-结构相互作用。 实验上：实验室原型装置由测试罐、加载框架和测量装置组成。粘土样品由干燥的高岭土粉末与约 60% 饱和度的水混合而成。直径为 100 毫米的增强粘土岩心样品将从储罐中取出并放置在三轴装置中进行测试。综合不排水 (CU) 测试将按照 ASTM (2004) 在泡孔压力下进行。测量设备的读数将由连接到个人计算机的数据采集系统（DAS）定期记录。 数值方面：将开发高保真度 3D 数值模型来检查控制该系统性能的参数的协同效应。将开发三个模型来模拟软土中石柱的安装过程，第二个模型是模拟（CU）三轴试验。从第一个模型测量的应力和变形将用作第二个模型的输入数据。第二个模型的结果将通过当前实验研究的结果进行验证。第三个模型是模拟由石柱加固的软粘土层上的柔性基础。 分析：从目前的实验和数值研究中推导出来的破坏机制将被理想化，并分为软粘土和沙子的切片，制作柱子，非圆形滑动面将使用非圆形切片的 Morgenstern-Price 方法进行分析滑动面和极限平衡技术。 该模型的结果将用作开发设计理论的基础，以预测系统的承载能力，并就经济设计的柱数和间距提出建议。