【作者】 徐洪；

【导师】 张永兴；

【作者基本信息】 重庆大学 ， 岩土工程， 2009， 博士

【摘要】 锚杆锚固系统作为现代岩土支护结构的重要组成部分,在社会经济发展中起着重要的作用,因此其工作性能的好坏将直接关系到社会的安定以及人民群众生命财产的安全。然而,由于锚杆锚固体通常处于恶劣的工作环境中,且服役时间较长,因此各国锚固工程中因耐久性不足而导致的破坏甚至失效的事件时有发生,尤其是近年来随着工程规模的扩大以及数量的增多,加之其工作环境的进一步恶化,锚杆锚固系统的耐久性问题更是日渐突出。目前针对工程结构的耐久性,国内外学者做过大量的研究,但所研究的对象主要为地面钢筋混凝土结构,这些结构无论是工作环境还是受力状态均与岩土锚固系统存在明显的差异,因此以往研究的成果不能很好适用于岩土锚固工程,进而开展该领域的研究就显得非常紧迫同时也很必要。本文以国家杰出青年科学基金项目“岩土工程减灾”(50625824)、重庆市建设科技计划项目“地质灾害防治工程耐久性技术”(城科字2006第62号)以及重庆市自然科学基金项目“在役地灾抗滑支挡结构耐久性研究”(CSTC,2008BB0318)为依托,分别对腐蚀条件下砂浆、锚杆自身性能的退化以及相互之间接触界面粘结特性的变化情况等影响砂浆锚杆锚固体耐久性的因素进行了基础性的研究,具体的工作及成果如下:①针对锚固系统中,腐蚀介质在砂浆中的扩散具有轴对称性且扩散路径长度有限的特点,利用数值分析方法模拟了砂浆锚固体内部腐蚀介质的传递规律,建立了以Fick定律为基础的砂浆内部腐蚀介质扩散模型。并考虑了砂浆开裂对内部介质运动规律的影响,建立了砂浆开裂情况下锚杆周边介质浓度变化规律模型。②通过对无锚杆砂浆试件及带锚杆砂浆试件的同步腐蚀,获得了砂浆强度随腐蚀时间的变化规律,以及砂浆-锚杆界面和锚杆-基体界面的粘结强度和荷载位移关系随腐蚀时间的变化特性,建立了砂浆腐蚀程度与界面粘结强度的对应关系,并考虑了室内试验与自然腐蚀条件的差异,将实验结果进行了推广。③通过对地下水存在条件下锚杆周围腐蚀电位的分析,给出了均匀腐蚀条件下锚杆的腐蚀电流密度,同时考虑了锚杆工作荷载对腐蚀电流密度的影响,建立了均匀腐蚀条件下工作锚杆的寿命计算公式;随后在考虑砂浆有缺陷的条件下,利用砂浆缺陷的几何特征以及阴阳极腐蚀电流密度关系,同时结合锚杆工作荷载在缺陷部位的应力集中,建立了砂浆缺陷条件下锚杆非均匀腐蚀的腐蚀寿命计算模型。④分别对围岩存在不考虑围岩初始应力和围岩存在同时考虑围岩初始应力影响两种情况下,锚杆腐蚀体积膨胀导致的砂浆开裂过程进行了分析,建立了适合岩土锚固体特点的锚杆砂浆锚固体锈胀开裂模型,并利用有限元分析方法对模型进行了验证。⑤利用粗糙度系数建立了锈蚀变形钢筋锚杆粘结强度参数随锚杆腐蚀程度的变化关系,并在此基础上采用数值分析方法对不同锈蚀程度下的锚杆在拔出过程中的极限荷载的变化情况,以及锚杆-砂浆界面、砂浆-围岩界面的粘结应力分布随锚杆的锈蚀程度的变化情况等进行了分析,对锚杆锈蚀以及砂浆的开裂对以上结果的影响过程进行了说明。以上研究过程对影响砂浆锚杆锚固体耐久性的各个方面分别进行了分析说明,研究成果以期能为以后展开更深入系统的研究起到抛砖引玉的作用。更多还原

【Abstract】 As a vital part of modern geotechnical supporting construction, bolt anchoring system plays an important role on the development of society and ecoeomy, so the durability and safety performance are derectly related to the stability of society and safety of people’s life and wealth. However, because of the adverse working conditions where bolt anchoring system always locate in and the long term of its service life, cases of durability deterioration or even damage always happen, especially with the expanding of engineering scal and the increase of engineering quantity, together with the further worsening of working environment, problems of durability damage becomes more and more outstanding. Recently, much work about durability of engineerning structure has been done at home and abroad, but most of these research productions can not be goodly applied on the bolt anchorage system, because most of these subjects investigated are reinforced concrete structures, there exist distinct differences in no matter the service conditons or stressing state between reinforced concrete structure and bolt anchoring system, so it is very urgent and necessary to carry out research of this field.Relying on the national excellent young science fund project“disaster reduction of geotechnical engineering”(50625824)、construction technology plan project of ChonqQing“durability technology of geological hazards control”and natural science fund project of ChongQing“research on durability of anti-slide supporting structure”(CSTC,2008BB0318) the basic research on durability of mortar bolt anchorage body, such as the self degeneration of bolt and mortar under the condition of corrosion, the changes of bond performance in each interface are analyzed, is conducted in this dissertation during the research cours. the concretely works and results are as follows:①Aiming at the characteristics of media erosion in anchoring system such as diffusing axial symmetrily and the limited length of diffusing. The movement characters of harmful medium diffusing in mortar is simulated by means of numerical analysis, the model of media diffusing in mortar which based in Fick’s law is built . Then the effection of cracks to media movement is considered, and the model of concentration distribution around bolt in cracked is also estamblished. The model results are highly agreed with the numerical results. ②Througth synchronous corrosion of mortar specimens with bolt and specimens without bolt, the relationship between mortar strength and corrosion time and the change of bond strength in bolt-mortar interface and mortar-rock interface alonge with the corrosion are achived.The relationship between mortar corrosion level and bond strength of each interface is built,beside that the difference between nature corrosion and laboratoury testing is considered and the test results is generalized.③First, by analyzing the corrosion potential of bolt in underground water environment, the corrosion current density of bolt uniform corrosion is provided at the same time , the effection of working load on corrosion current density is considered, and the model of corrosion life of bolt under condition of uniform corrosion is built.Second , with the premise of mortar defectiveness, by using of the relationship between defectiveness size and corrosion current, also considering the stress concentration in defectiveness position, the model of bolt corrosion life under the condition of unequally corrosion is slso estambilished.④The process of motar cracking caused by bolt corrosion and its volume expansion under two tipes of conditions, one is to consider the rock initial stress and the other is not to consider the rock initial stress, the model which is suit to bolt anchoring system’s characteristics is estambilished, the model is validated by finite element analysis.⑤Based on coefficient of rugosity, the model of bond strength parameter of deformed bar bolt in different corrosion level, based on the model, the anchoring character such as ultimate load in the extracting process、the distribution of bond strength in bolt-mortar interface and mortar-rock interface,changing with the bolt corrosion degree is analyzed by means of numerical analysis method, and the affection of bolt corrosion and mortar cracking to above anchoring characts are also explained..From above research procees, all of the aspects which affect the durability of bolt anchoring system are illustrated, the results is hoped to provide a reference to more deepper and more systemic research later.更多还原