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Expanded pore-emanated cracking model for brittle failure of sedimentary rocks under triaxial compression

Journal of Rock Mechanics and Geotechnical Engineering 2024年第12期16卷 5050-5060页

作者： Esraa M.Alomari Kam Ng Lokendra Khatri Department of Civil and Architectural Engineering and Construction Management University of WyomingLaramieWY82071USA kiewit Corporations ColliersvilleNew YorkNY13747USA

Brittle fracture and its relationship to deformation and strength have been a fundamental area of research in rock *** paper presents an expanded pore-emanated cracking model to better understand the fracture behaviors and predict the compressive strength of sedimentary *** proposed model is developed to account for a triaxial compression condition using the triaxial compression test results on sandstone,limestone and siltstone samples from Wyoming,USA and experimental data on sedimentary rocks collected from published *** normalized critical crack length is determined from the proposed model through which the peak compressive strength is estimated when the stress intensity at the crack tip reaches a critical value called the fracture *** indicate that the rock porosity and pore radius have an inverse relationship with the compressive *** the porosity-permeability relationship,the pore radius is calculated in terms of porosity and grain ***,the effect of grain size is implicitly included in the model and negatively correlated with the compressive ***,a new approach is proposed for the estimation of fracture toughness based on the pore radius and confining *** predicted compressive strengths from the proposed model show a good agreement with the measured strengths with a mean bias(*** ratio of the measured to predicted strengths)of *** influence ofφand K_(IC)onσ1 was thoroughly studied using parametric *** study concludes that the effect ofφis more prominent than K_(IC)onσ*** a constant porosity of 0.1,the stress ratio decreases from 0.0082 to 0.0078 when K_(IC)increases from 0.1 to 0.2,indicating a 5%decrease in stress ***,at a constant K_(IC)of 0.1,the stress ratio increases from 0.0082 to 0.014 when the porosity increases from 0.1 to 0.2,indicating 71%increases in stress ratio and therefore compressive strength.

关键词： Compressive strength Mode I fracture toughness Porosity Pore radius Confining pressure

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BEHAVIOUR OF PLASTERED STRAW-BALE ASSEMBLIES SUBJECTED TO THREE-POINT BENDING

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Journal of Green Building 2012年第3期7卷 95-113页

作者： Michael Rakowski Colin MacDougall kiewit-Alarie KapuskasingOntario Department of Civil Engineering Queen’s UniversityKingstonOntarioCanada

The search for more sustainable construction methods has renewed interest in straw-bale *** straw bales stacked in a running bond and plastered on the interior and exterior faces have been shown to have adequate strength to resist typical loads found in one-and two-storey *** straw bales provide excellent insulation,while possessing low embodied energy compared to conventional insulation *** structural behaviour of a load-bearing plastered straw-bale wall subject to uniform compressive loading has been the focus of a number of studies reported in the ***,in a typical building wall,there will be numerous locations(such as around window and door openings)where the load paths produce areas of concentrated *** behaviour in these regions cannot necessarily be predicted using tests from uniformly loaded wall *** paper describes experiments on plastered single bale assemblies subjected to three-point *** assemblies develop shear and flexural stresses,and so simulate the stresses that exist around door and window openings in a *** specimens were rendered with lime-cement plaster,and were either unreinforced,or contained steel“diamond lath”mesh embedded within the *** specimens were pin-supported at various centre-to-centre distances(L)ranging from 200 mm to 500 *** height(H)of all specimens was constant at 330 *** gave a range of H/L values of 0.66 to *** distinct types of failure were *** tests with H/L1,failure was due to crushing of the plaster in compression under one of the loading *** was shown that models based on simple mechanics were able to adequately predict the assembly *** particular,analysing the assemblies with H/L<1 as simple beams,and using the transformed section concept to deal with the stra

关键词： straw bale construction cement-lime plaster discontinuous regions structural testing 3-point bending

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A constitutive model incorporating particle breakage for gravelly soil-structure interface under cyclic loading

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Science China(Technological Sciences) 2022年第12期65卷 2846-2855页

作者： CUI Hao XIAO Yang SHU ShanZhi HE Xiang LIU HanLong School of Civil Engineering Chongqing UniversityChongqing 400045China Key Laboratory of New Technology for Construction of Cities in Mountain Area Chongqing UniversityChongqing 400045China kiewit 10055 Trainstation CircleLone TreeCO 80124USA

Under cyclic loading,particle breakage occurs at gravelly soil-structure interface,resulting in the decrease of interface strength and the increase of normal *** on the theory of critical state soil mechanics,the modified Cam-Clay model(MCC)was extended to the plane strain condition of the interface,the state parameter was introduced and the influence of particle breakage on the critical state line was considered,and the cyclic constitutive model for gravelly soil-structure interface considering particle breakage was established by using the non-associated flow ***,the established cyclic constitutive model was used to simulate large-scale cycle direct shear tests of Zipingpu rockfill-steel interface and Zipingpu rockfill-concrete interface under constant normal load(CNL)and constant normal stiffness(CNS),*** simulation results show that under the CNL cyclic loading path,there is little difference between the cyclic shear stress considering particle breakage and that without particle breakage,but the normal displacement considering particle breakage is larger than that without particle breakage,and the difference increases with the increasing number of cycles and normal stress;Under the CNS cyclic loading path,with the increase of the number of cycles,the cyclic shear stress and cyclic normal stress considering particle breakage is significantly smaller than that without particle breakage,and the shear contraction of normal displacement becomes more *** general,the simulation results are closer to the experimental results when particle breakage is considered.

关键词： gravelly soil-structure interface particle breakage cyclic loading constitutive model

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Comparing Design Void Content with Actual Void Content of Laboratory Prepared Pervious Concrete

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Materials Sciences and Applications 2018年第7期9卷 596-613页

作者： Anthony Torres Cristián Gaedicke Jiong Hu Rupesh Bejugam Sarah McMasters Texas State University San Marcos TX USA California State University Hayward CA USA The Peter kiewit Institute University of Nebraska-Lincoln Omaha NE USA

The goal of this study was to compare the predicted void content with the actual void content of pervious concrete cylinders. All pervious concrete systems are designed with a void content in mind to facilitate a specific permeability;however, due to variable placing techniques and inherent issues with the material, the actual in place void content often varies from designed. This study quantifies this difference and attempts to develop a correction factor, such that design values are more approximate to in place pervious concrete systems. The analysis included multiple mixtures with three design void contents (15%, 25%, 35%), two aggregate types (angular and rounded), and three different water-to-cement ratios (0.33, 0.37, 0.41). These samples were methodically designed to contain a desired void ratio, then casted in the laboratory, in which the compaction of each sample was controlled for consistency. Following casting, the in-place void content was determined using ASTM C1754 and compared to the predicted. The difference was then averaged to create a correction factor requiring more or less cement paste, which was used to redesign the mixtures. The new mixtures were then compared to the predicted void content. The results of this study show that initial designs can vary from 3% - 15% on average from initial designed void content and that a correction factor can be used to obtain within 3% on average of the target void ratios.

关键词： Pervious Concrete Void Content Permeability Compaction

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考虑钙质砂颗粒破碎的分数阶边界面本构模型

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岩土工程学报 2023年第6期45卷 1162-1170页

作者：汪成贵束善治肖杨路德春刘汉龙重庆大学土木工程学院重庆400045 kiewit 10055 Trainstation CircleLone TreeCO 80124 重庆大学山地城镇建设与新技术教育部重点实验室重庆400045 库区环境地质灾害防治国家地方联合工程研究中心重庆400045 北京工业大学城市与工程安全减灾教育部重点实验室北京100124

钙质砂作为海洋工程中广泛应用的建筑材料,颗粒破碎会导致其强度和剪胀性降低,压缩性增加,影响构筑物的安全和稳定。通过引入破碎应力建立考虑颗粒破碎的临界状态线来描述破碎对临界状态线位置和形状的影响;并基于分数阶微分和状态相关... 详细信息

钙质砂作为海洋工程中广泛应用的建筑材料,颗粒破碎会导致其强度和剪胀性降低,压缩性增加,影响构筑物的安全和稳定。通过引入破碎应力建立考虑颗粒破碎的临界状态线来描述破碎对临界状态线位置和形状的影响;并基于分数阶微分和状态相关理论建立了统一的状态相关分数阶塑性流动法则;在边界面塑性理论和临界状态理论框架下建立了考虑钙质砂颗粒破碎和状态相关特性的分数阶塑性边界面本构模型。模型能够模拟不同初始密实度和围压条件下钙质砂三轴排水试验结果和颗粒破碎影响下的状态相关行为,并验证了模型的适用性。

关键词：钙质砂颗粒破碎状态相关分数阶本构模型

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