【作者】 李平先；

【导师】 赵国藩； 张雷顺；

【作者基本信息】 大连理工大学 ， 结构工程， 2004， 博士

【摘要】 本文的研究工作属国家基础性研究重大项目(攀登计划B)《重大土木与水利工程安全性与耐久性的基础研究》之5.2(1)子课题“新老混凝土的粘结机理和测试方法研究”及国家自然科学基金项目(59778045)“新老混凝土的粘结机理研究”课题子项。 抗冻性和抗渗性是衡量混凝土材料耐久性的重要指标，也是评价新老混凝土粘结面耐久性的依据。针对水工混凝土结构补强加固中，新老混凝土粘结面在寒冷地区由于气候变化引起的温度变化而产生冻融循环，由此可能导致粘结面产生冻融破坏，以及粘结面在水压力作用下可能产生渗漏这一特点，对新老混凝土粘结面在冻融循环作用下的力学性能及粘结面的渗透性能进行了试验研究，以期对新老混凝土粘结面的安全性和耐久性做出正确的评价。 本文的主要工作如下： 1．进行了162块老混凝土立方体试件在经受0，25，50，75，100和125次冻融循环后与新混凝土粘结的复合立方体试件粘结面劈裂抗拉强度试验，和162块新老混凝土复合立方体试件粘结后再经受0，5，15，20，25和30次冻融循环时的劈裂抗拉强度试验研究。探讨了混凝土本身和新老混凝土粘结试件的冻融损伤机理，以及影响新老混凝土粘结性能的主要因素，如冻融循环次数、界面粗糙度、界面剂类型、界面处理方法等。试验结果表明，新老混凝土的粘结劈裂抗拉强度随冻融循环次数的增加而下降，特别是先粘结后冻融试件，其粘结面的劈裂抗拉强度受冻融循环的影响尤为明显，表现为粘结面的劈裂抗拉强度随冻融循环次数的增加呈现陡降趋势。界面粗糙度和界面剂对粘结面劈裂抗拉强度也有不同程度影响。 2．进行了216个加气新老混凝土粘结复合立方体试件经受0，10，20，30，40，50，60和70次冻融后的劈裂抗拉强度对比试验，探讨了引气剂对新老混凝土粘结面抗冻融性能的影响。结果表明，引气剂可明显提高新老混凝土粘结面的抗冻融性能，对所试验的试件，在同样的条件下，其抗冻融性能可提高一倍。 3．采用Z形复合粘结试件，对162个先冻后粘结和135个先粘结后冻融试件的直剪试件进行了试验，主要考察了冻融循环次数、界面粗糙度、界面剂类型及界面处理方式对新老混凝土粘结面剪切强度的影响。并对新老混凝土粘结面冻融损伤机理进行了探讨。结果表明，新老混凝土粘结面的剪切强度随冻融循环次数的增加而降低，对先冻后粘结试件表现为冻融循环初期时的缓降和一定冻融循环次数后的陡降；而先粘结后冻融试件则一开始就表现为粘结面剪切强度随冻融循环次数呈急剧下降趋势。 4．在现有抗渗试验机上，设计了新老混凝土粘结复合园台体渗透试件，进行了168个试件的试验。主要考察了界面处理方法、界面剂类型、以及在老混凝土粘结面刻糟等，对粘结面渗透性的影响，对粘结面的渗流特性及层面力学参数，如粘结面等效水力隙宽、渗透系数以及渗透规律进行了探讨。结果表明，新老混凝土粘结面的渗透性大于新、老混凝土本体的渗透性，粘结面是其渗水的主要通道;粘结面的渗流基本上属于层流渗流。在此基础上，根据粘结面的渗水高度，推导了粘结面的等效水力隙宽及渗透系数的计算公式。经计算，粘结面的等效水力隙宽在0.11一0.27娜之间，渗透系数多数在1.IX10一’o一4.8 x 10一，cm/s之间，个别高达1.8x10一‘一2.5x10一‘Cm/s。5.在现有粘结面处理方法的基础上，提出了采用环氧砂对粘结面进行糙化处理的方法。通过对比试验，证明了该方法的可行性和可靠性次进行试用，取得了良好效果。，并在某水利工程闸底板修补中初 6.在新老混凝土粘结机理和试验研究成果的基础上，混凝土之间的粘结在轴拔情况下的试验结果进行了分析，对预应力混凝土大管桩与桩帽并对其粘结滑移特性在理论上进行了探讨。文中推导的粘结滑移理论表达式满足边界条件，与Mindlin的弹性理论分析在形式上相似。在试验的基础上，结合新老混凝土粘结强度试验结果，给出了预应力混凝土大管桩与桩帽混凝土粘结在轴拔情况下的极限承载力计算公式，其结果与试验吻合较好。更多还原

【Abstract】 The thesis is a part of subject "Research on mechanism of adherence and measure method of young on old concrete", which is sub-subject of national momentous foundational research subject (Climbing Project B)《The foundational study on safety and durability of great civil and water conservancy engineering》 , and national nature science found(59778045) 《Study on mechanism of adherence of new-old concrete》 .Freeze-thaw resistance and impermeability usually are used as a key index to measure the durability of concrete, which are also as an important basis to evaluate the durability of new-old concrete adherence. In cold areas, seasonal and daily temperature variations have caused numerous freezing-and-thawing cycles, especially for those repaired hydraulic concrete structure, resulting in differential thermal expansion between the new and the old concrete. Differential expansion could contribute to bond damage, premature bond separation, or both, resulting in failure of the bond of new-old concrete. And the adherence of new-old concrete may produce seepage under water pressure. The author had conducted experimental research on the mechanical properties of the interfacial bond of new-old concrete exposed to freeze-and-thaw cycles and the impermeability under water pressure, and hoped that the research could be used to evaluate the safety and durability of bond performance after having been repaired and retrofitted.The main contents of research are as follows:1.Using composite cubic specimens of new-old concrete, the bond splitting tensile strength for the interface of new-old concrete in saturating state were explored when exposed to freeze-thaw cycling. 162 old concrete cubic Specimens were experienced zero, 25, 50, 75 and 100 and 125 freezing cycles for old concrete before bonded with new concrete to, and zero, 5, 10, 15, 20, 25 and 30 for 162 composite specimens were bonded prior to freezing-and-thawing. The freezing deteriorate mechanism of concrete itself and adherence of new-old concrete were discussed. The freezing cycles, roughness and types of adhesion agent were also investigated. The test results indicated that the bond splitting tensile strength decreased with increasing numbers of freezing-and-thawing cycles, and that the rate of decrease was greater for specimens that were bonded prior to freezing-and-thawing. The roughness and adhesion agent had different effect on the bonding strength.2. The bond splitting tensile strength of 216 composite cubic specimens with air-entraining agent were tested when subjected to zero 10, 20, 30, 40, 50 and 60 and 70 freezing cycles. The effect of air-entraining agent for the frost resistance of new-old concrete was studied. The test results indicated that the frost resistance of specimens for new-old concrete with air-entraining agent exposed to freezing cycles was two times that of those specimens without air-entraining agent.3. Using Z-shape specimens of new-old concrete, the bond shear strength for the interface of new-oldconcrete in saturating state were explored when subjected to freeze-thaw cycling. 162 Specimens were experienced zero, 25, 50, 75 and 100 and 125 freezing cycles for old concrete was frosted before bonded, and 5, 10, 15, 20, 25 and 30 for 135 composite specimens were bonded prior to freezing-and-thawing. The freezing cycles, roughness and types of adhesion agent were also investigated. The test results indicated that the bond shear strength decreased with increasing numbers of freezing-and-thawing cycles. The shear strength of new-old concrete, for those specimens were bonded before exposed to freezing-and-thawing, declined slowly with increased numbers of freezing-and-thawing cycles at the beginning of freezing cycles and abruptly decreased after a certain numbers of freezing-and-thawing cycles. And the rate of decrease was abrupt at the beginning of freezing for those specimens were bonded prior to subjecting to freezing.4. According to impervious testing machine, the composite impervious specimen was designed and 168 specimens we更多还原