【作者】 温小栋；

【导师】 马保国；

【作者基本信息】 武汉理工大学 ， 建筑材料与工程， 2007， 博士

【摘要】 随着城市化进程的加快，土地资源短缺的问题日益突出，对地下空间的大规模开发已成必然趋势。由于地下混凝土结构工程所服役环境更为恶劣、服役年限更长，要求其具有高耐久性。而混凝土体积稳定性是其耐久性研究中的首要内容。针对当前对梯度结构混凝土体积稳定的研究甚少，本论文依托武汉长江隧道工程和国家“863”课题《高抗渗长寿命大管径隧道管片材料结构设计与工程应用》，开展基于体积稳定性的梯度结构混凝土的设计、研究与应用．主要工作和得到的结论如下：1、首次提出基于体积稳定性的梯度结构混凝土设计理念与方法依据毛细管张力学说、结晶膨胀机理建立体积变形物理模型；并对混凝土体积变形破坏机理进行分析，提出膨胀可调控技术、裂缝细微化与自愈合理论，并结合现有的补偿收缩机理、热稳定性机理，为制备出高体积稳定性混凝土提供理论依据；将梯度概念混凝土引入设计中，提出梯度功能结构设计原理及方法，实现保护层的防护功能，要求其具有高抗裂、自修复及致密性特点，结构层提供结构支撑功能，要求其与养护制度相匹配，从而建立梯度功能结构混凝土结构体系。2、以钙硅铝质超细粉体材料、小分子聚醚类等作为变形抑制组分，以有机混杂纤维及就地反应堵塞型修复材料作为抗裂自修复组分，通过单因素试验分析研制出一种新型的抗裂自愈合掺合料（简称：ACSH）。与等量的粉煤灰基准样（25％）进行作用效应对比分析，结果表明：①力学性能在秋季自然养护下，可使12h脱模抗折强度提高144％，抗压强度提高119％；28d抗折强度提高9％，抗压强度提高7.5％；②体积变形1d时收缩值下降67％，28d收缩降低31％及90d降低23％；在80℃沸煮箱养护14d下膨胀率下降25％；③开裂敏感性开裂时间由96h延长到121h，裂缝宽度降低50％；④自修复能力强度回复率由0.72增大到0.92，提高了25％。3、首次针对梯度结构混凝土的保护层——无细观界面过渡区水泥基复合材料进行力学性能、徐变性及收缩变形研究，并对其随龄期的发展规律进行分析如下：①弹性模量根据Mosley模型对试验结果进行回归，其弹性模量随龄期的发展规律为：E_t=E₂₈[0.40+0.19×log（t）]（t≤8）（R²=0.96264），E_t=1.019 E₂₈（t＞28）；②劈拉强度根据ACI C209对试验结果进行回归，其劈拉强度随龄期的发展规律为：f_sp=6.92t／（1.7+t） （R²=0.98374）；③早期徐变性根据ACI（1978）提出的双曲线模型试验结果进行回归，其早期徐变度随龄期的发展规律为C_t=38.7t／（6.3+t）（R²=0.98934）；④收缩变形根据ACI（1978）提出的双曲线模型对试验结果进行回归，其收缩变形随龄期的发展规律为ε=560.2t／（8.2+t） （R²=0.99561）。4、针对隧道管片混凝土常采用的蒸气养护，模拟出养护温度与水化热协同作用下混凝土内部的温度历程；并系统研究在此温度历程下材料组分对结构层中AFt稳定性的影响其结果表明：①长度变化在40℃的水环境下，早期按模拟的温度历程养护的纯水泥体系及单掺UEA补偿收缩体系在第一次快速膨胀变形稳定后的约60d再次发生明显的膨胀变形；但掺加矿物掺合料（如，矿粉），可以明显抑制后期的过度膨胀；例外，NS外加剂的掺入促进早期膨胀，后期膨胀稳定，有利于其体积稳定性。②XRD分析早期按内部温度历程养护的纯水泥体系及单掺UEA补偿收缩体系易发生钙矾石和单硫型水化硫铝酸钙晶形转变；而密封后再按内部温度历程养护后，早期高温分解的钙矾石在后期降温阶段不会再次形成。掺入适量的NS外加剂可以增强钙矾石的稳定性及钝化其晶形转变的温度效应。③SEM分析掺加矿物掺合料（如，矿粉SL），生成长板状的非膨胀性钙矾石；而纯水泥体系及单掺UEA补偿收缩体系形成针棒状的膨胀性钙矾石。在降温阶段后，密封养护的纯水泥体系在孔隙中只发现卷叶状的单硫型硫铝酸钙，而未发现针棒状钙矾石。5、对制备出梯度结构混凝土（GSC）进行体积变形评价和多因素作用下的抗裂性能评价，并应用于武汉长江隧道工程①首次对梯度结构混凝土保护层和结构层体积变形的匹配性进行研究，并采用界面力学的方法对梯度结构混凝土体积变形一致性进行评价，计算结果表明，优化后的梯度结构混凝土具有良好的体积变形协调性，不会出现非一致性破坏。②由于实际工程中混凝土绝大多数是单面暴露在环境中，因此本文采用单面千燥环境来评价高压富水的地下工程混凝土失水后的收缩变形，同时采用单面地下水环境评价地下工程混凝土在高压富水后的膨胀变形。试验结果表明：与纯水泥体系比较，GSC单面干燥收缩变形28、90d下降26％和30％，单面地下水环境引起的膨胀变形44周下降74％；与掺25％的矿粉复合水泥体系相比，GSC单面干燥收缩变形28、90d分别下降12％和17％，单面地下水环境引起的膨胀变形44周下降60％。这表明FGSC可明显抑制混凝土长期体积变形，有利于其体积稳定性。③借鉴平板约束开裂法，进行稳定环境（温度30±1℃，相对湿度为50±5％，风速为2m／s）下单因素抗裂性能评价，试验结果表明：14d稳态环境下FGSC未出现可见裂缝，而掺25％矿粉的复合水泥体系6h出现0.2mm的可见裂纹；④成型尺寸比例为1∶5的管片进行地下水和温度循环共同作用下的多因素抗裂性能评价，采用超声波波速及电通量变化率来表征温度循环和地下水作用带来的微裂纹损伤度。结果表明，采用超声波波速变化率评价时，GSC体系的平均损伤程度为0.18，而25％矿粉体系混凝土为0.38：GSC体系的电通量由标养时149库仑略增加到252库仑，其平均损伤度为0.70，而25％SL体系混凝土由标养时的1267库仑增加到2728库仑，其平均损伤度为1.15。这表明GSC体系具有更好的抗裂性能。⑤采用梯度功能结构混凝土制备出1∶1管片应用于武汉长江隧道工程，其管片混凝土28d干缩率为1.95×10⁴，90d干缩率为2.45×10^-4。6、对比和分析了国内外水泥基材料体积变形测定方法，研发了一种多环境下水泥基材料体积变形在线监测仪及方法。①采用环境模拟技术来模拟所需的工程环境（温度、湿度及气体浓度，等）；②采用激光和电涡流测微技术扩大其使用范围，如：高温、高湿及尘埃环境；③采用多通路设计和自动控制方法实现在线监测及数据的自动采集，同时对多组试件进行测试，降低了测试成本，提高使用效率；④对模具进行改进，使测试过程可不需拆模，不需移动试件，可消除或减缓外界的干扰，同时避免试件成型时预埋测头的内外窜动及倾斜，从而提高测试精度；⑤此测试仪器和方法适用于玻璃、陶瓷、石材和墙体材料等的变形测试。更多还原

【Abstract】 With the acceleration of urbanization, the problem of land resource shortage have become more and more serious, and the exploitation of the space underground has been an inevitable current. Due to the worse service environment and the longer service life of concrete structure in Seaport Engineering, it requires high durability. And the most important thing of its durability study should be volume stabilization of concrete. But, considering that there are few researches on volume stabilization of gradient structure concrete （hereinafter referred to as "GSC"） nowadays, this paper according to Wuhan Yangtze River Tunnel Project and National 863 Project （Structure Design of highly anti-resistant, long life and large diameter tunnel segment material and Its Application）, the graded structure concrete based on volume stabilization were designed, studied and applied in this thesis. The main achievements are listed as follows:1. Design idea and method of GSC based on volume stabilization was put forward for the first timeOn the basis of capillary tension theory and crystallization expansion mechanism, the Physical Model of volume deformation was build. And by mechanism analysis on destruction of concrete volume deformation, controlling technique of expansion and theory of crack refinement and self-healing were put forward which will provide theoretical basis for preparation of high volume stability concrete combined with the existing theory of shrinkage-compensating, one after another hydration and thermal stability.Leading the conception of gradient structure into the concrete design, this thesis put forward method and principle of gradient structure design which should require the protective layer of concrete has the characteristics of high crack resistance, self repair and compactness for its shelter function, and require the structure level matching to curing system for its structural support function. As a result, structural system of GSC was established.2. A new kind of anti-cracking and self-repairing additive （hereinafter referred to as "ACSH"） was developed by single-factor test, using small molecule polyether and ultra-fine powder material containing calcareous and sialic resource as inhibitory component of deformation, organic hybrid fiber and "block" type repairing material with in-situ reaction as anti-cracking and self- repairing component.As compared with reference concrete with 25% fly ash, the result showed that:①Mechanical PropertiesCompressive strength, flexural strength of the concrete mixed with 25% ACSH were increased by 119% and 144% at 12 hours, and enhanced by 7.5% and 9% at 28 days respectively under the natural curing conditions in autumn.②Volume StabilizationThe shrinkage was declined by 67%, 31% and 23% at 1, 28 and 90 days respectively. Moreover its expansion value in boiling case at 80℃was decreased by 25% at 14 days.③Cracking SensitivityThe cracking time was prolonged by 26%, and its cracking width was declined by 50%.④Self-Repairing AbilityThe strength recovery ratio was increased from 0.72 to 0.92, and it was enhanced by 25%.3. The mechanical property, specific creep and shrinkage deformation of meso-defect interface transition zone free cement based material were investigated against protective layer of GSC. And the regularity of their growth with ages was analyzed, as follows:①Elastic ModulusAccording to Mosley model, experimental results were regressively analyzed to reach a regularity of elastic modulus growth with ages, and the regularity is E_t=E₂₈[0.40+0.19×log（t）] （t≤28） （R²=0.96264）, E_t=1.019 E₂₈ （t＞28）.②Split StrengthConducting regressive analysis of experimental results by ACI C209, the regularity of split strength growth with ages is f_sp=6.92t/（1.7+t） （R²=0.98374）.③Early Specific CreepAccording to hyperbolic model proposed by ACI （1978） to conduct regressive analysis of experimental results, the regularity of early creep growth with ages is C_t=38.7t/（6.3+t）（R²=0.98934）.④Shrinkage DeformationAccording to hyperbolic model proposed by ACI （1978） to conduct regressively analyze experimental results, the regularity of shrinkage growth with ages isε=560.2t/（8.2+t）（R²=0.99561）.4. According to steam-curing usually used in tunnel segment concrete, the temperature history in interior of steam curing concrete taking account of synergistic effects of hydration heat of cement and temperature of steam-curing were simulated. And effect of material constituents on stabilization of ettringite in structure level was investigated in this temperature history.The result indicated that:①Length ChangesUnder the water environment at 40℃, for pure cement system and shrinkage compensating system mixed singly with UEA which were cured in simulated temperature history, their swelling strain stared increasing again at about 60 days after the stabilization of first rapid swelling. While the system mixed with mineral additive, such as slag, might inhabit obviously the later overexpansion. Moreover, the NS additive might accelerate early expansion, and also stabilize the later expansion, which were beneficial for volume stabilization of concrete.②XRD AnalysisFor pure cement system and shrinkage compensating system mixed singly with UEA which were cured in simulated temperature history at an early age, they were susceptible to crystal shape transformation between ettringite and calcium monosulphoaluminate （hereafter referred to AFm）, which is to say, ettringite formed in the early hydration period decomposed to AFm when it had experienced elevated temperature, and following ettringite decomposed by high temperature was re-crystallized during cooling; While they were cured in simulated temperature history after sealing, ettringite decomposed during elevated temperature was not re-crystallized during cooling.Moreover the NS additive might enhance the stabilization of ettringite and passivate the temperature effect of crystal shape transformation.③SEM AnalysisFor pure cement system and shrinkage compensating system mixed singly with UEA, the needle-like expansive ettringite crystals were formed. While in cement system mixed with mineral additive the large plate-like non-expansive ettringite crystals were formed.Moreover, adopting sealed curing, the leaf-like AFm crystals were found in pore of pure cement system during cooling, but the needle-like ettringite wasn’t.5. Anti-cracking under multiple factor action and volume stabilization of GSC was appraised, and it was applied to Wuhan Yangtze River Tunnel Project.①The matching of volume deformation between protective layer and structural level of GSC was first studied, and it was estimated by interface mechanics. Moreover the calculating result indicated that the optimized GSC had good compatibility of volume deformation, and it didn’t cause the inconsistency damage.②Due that most concrete was exposed to environment from a single side, in this thesis the shrinkage deformation of concrete in underground engineering with High-Pressure and Rich Water after dehydration was estimated by a single side exposed dry environment, at the same time, the swelling deformation of its concrete after High-Pressure and Rich Water was also estimated by a single side exposed groundwater environment. The test result showed that as compared with pure cement system, the shrinkage of GSC under the condition that the single side was exposed to dry environment was declined by 26%, 30% respectively at 28, 90days, at the same time, the swelling of GSC, in which the single side was exposed to groundwater environment was declined by 60% at 44 weeks. While as compared with cement system mixed with 25% slag, the shrinkage was declined by 12%, 17% respectively at 28, 90days, and the swelling was decreased by 60% at 44 weeks. This indicated that FGSC could inhabit the long term volume deformation, and benefit for its volume stabilization.③by the restrained slab test, specimen was adopted to fulfill the comparative test for single factor evaluation on anti-cracking Performance under the stable environment （temperature 30±1℃, relative humidity 50±5%, wind speed 2m/s）.The results showed that the visible crock appeared in GSC stayed in this environment for 14 days, but the visible crack with 0.2mm width appeared in 6 hours for cement system mixed with 25% slag.④the segment prepared according to 1:5 dimension scales was adopted to fulfill the comparative test for multi-factor evaluation on anti-cracking performance under the combined action of underground and temperature cycle, additionally damage degree of micro-crack caused by underground and temperature cycle was characterized by the change rate of ultrasonic velocity and electric flux.The results showed that by means of change rate of ultrasonic velocity, the average damage degree of GSC system was 0.18, but the cement system mixed with 25% was 0.38. Moreover, the electric flux of GSC system was increased from 149 Q to 252 Q, and its average damage degree was 0.70, while the cement system mixed with 25% was increased from 1267Q to 2728Q, and its average damage degree was 1.15.It indicated that GSC system had a better anti-cracking performance⑤The segment prepared according to 1:1 dimension scales using GSC system was applied to the Wuhan Yangtze River Tunnel Project, and drying shrinkage ofthe segment concrete was 195, 245 respectively at 28, 90 days.6. Comparing and analyzing some measuring means of volume deformation for cement-based materials at home and abroad, a kind of online monitor for monitoring volume deformation of cement-based materials in multiple environments and its method was developed.①Use environment simulation technology to simulate the engineering environment such as temperature, humidity, and gas intensity, etc.②Use micro-distance measuring technology of laser and eddy current to enhance the serviceable range of this development such as high temperature, high relative humidity and dust environment.③Use the multi-channel design and auto-control method to gather experiment data automatically, monitor on-line, at the same time, decline the measuring cost, enhance the service efficiency.④By means of the modified mould, it needn’t to break the mould or move the specimen during measuring process, which could avoid external disturbances. Meanwhile, it could prevent gauge heads from leaping and leaning when the specimen was molded and thereby the testing accuracy could be enhanced.⑤This testing method and the equipment is also suitable for measuring deformation of materials such as glass, ceramics, stone materials, walling materials and etc.更多还原