Development, experimental validation, and applications of 3D hydro-mechanical concrete fracture models for structural safety evaluation and rehabilitation of concrete hydraulic structures subjected to

3D 水力混凝土断裂模型的开发、实验验证和应用，用于混凝土水工结构的结构安全评估和修复

• 批准号: RGPIN-2014-05418
• 负责人: Léger, Pierre
• 金额: $ 2.04万
• 依托单位: École Polytechnique de Montréal
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2015
• 资助国家: 加拿大
• 起止时间: 2015-01-01 至 2016-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=588407
• 关键词: Development; experimental; validation; applications; 3D

Existing concrete gravity, arch dams, and gated spillways are expected to sustain damage in the event of extreme events such as floods and earthquakes inducing concrete cracking raising major concerns to maintain structural stability. The objectives of the proposed research program are (i) to develop innovative 3D hydro-mechanical modelling methodologies to quantify the safety of concrete dams and spillways considering cracking and uplift pressures (diagnostic aspects), (ii) to determine experimentally mass concrete constitutive parameters to model joints/cracks (validation aspects), and (iii) to study the effectiveness of actions to repair/strengthen cracked dams by grouting drainage, and added steel elements (rehabilitation aspects). Effective and innovative assessment / rehabilitation strategies of concrete hydraulic structures will permit substantial saving on costly remedial work. The proposed research program is divided into two projects: Project 1 –3D Stability Evaluation and Rehabilitation of Cracked Concrete Gravity Dams and Spillway piers using fiber elements: Existing gravity hydraulic structures (dam, spillway, intake) are complex structures with limited ductility that are sensitive to lateral seismic excitations that have often been ignored in the past. We will pursue the development a novel robust and computationally efficient 3D coupled nonlinear hydro-mechanical model using (a) strength of material, (b) beam-column theory combined with (c) 2D sectional finite element analyses to account for axial-flexure-shear-torsion interactions leading to a "hydro-mechanical" fiber element suitable for static and seismic safety assessment. Sectional properties will be integrated along the element to form the mass and the stiffness matrices to be assembled with other elements to represent the complete structure. Failure criteria will be considered for the flexural and shear strengths that could be mobilised within the context of hydraulic structures. Cracking along lift joints (or arbitrary planes) will be modelled including water penetration in cracks. Detailed 3D FE analyses will be used to validate the proposed macro-element (fiber element) approach directed towards robust and efficient industrial applications. A particular attention will be given to the following aspects that have not been extensively studied in the past, (i) simultaneous 3D cracking along multiple planes, (ii) stability of cracked components in the presence of uplift pressures and limited, old steel reinforcement, (iii) consideration of phases of construction (presence of shear key, initial stress-strain condition before repair), (iv) application of post-tensioning, steel or concrete jacketing to reinforce weak piers. Project 2 -Strengthening of Cracked Dam by Cement Grouting and Drainage: Grouting is used to restore water tightness and reduce uplift pressures in cracked dams. However, the post-grouted stress-strain state and the gains in tensile and shear strengths are very difficult to quantify. No work has been reported on mechanical strength of grouted mass concrete cracks subjected to different load paths representative of in situ conditions. The safety assessment of grouted dam will be tackled by (a) development of a novel hydro-mechanical finite element model with drainage in a multi-physic problem coupling different hydraulic and mechanical meshes in the presence of drains in the dam body (re drilled after grouting), and (b) 3D innovative experimental testing of grouted mass concrete blocks to validate constitutive models for grouted cracks. Special adhesive (gap)-friction grout finite element will be developed. Case studies will be performed on cracked arch dams.

现有的混凝土重力坝、拱坝和门控溢洪道在洪水和地震等极端事件中可能会遭受破坏，导致混凝土开裂，这是保持结构稳定性的主要问题。拟议研究计划的目标是(i)开发创新的3D水力学建模方法，以量化考虑裂缝和提升压力的混凝土大坝和溢洪道的安全性（诊断方面），（ii）通过实验确定大质量混凝土的本构参数来模拟接缝/裂缝（验证方面），以及（iii）研究通过灌浆排水修复/加强裂缝大坝的行动的有效性。并添加了钢元素（修复方面）。有效和创新的混凝土水工结构评估/修复策略将大大节省昂贵的修复工作。拟建的研究计划分为两个项目：