【作者】 李英勇；

【导师】 王梦恕；

【作者基本信息】 北京交通大学 ， 岩土工程， 2008， 博士

【摘要】 基于大量的文献研究和实践,籍助济南绕城高速公路现场实测资料,利用理论分析、现场试验、室内试验和数值模拟等研究手段,对岩土预应力锚固系统长期稳定性进行了全面系统的深入研究,并结合实际工程对本文的研究思想进行了应用研究,确定了实际工程司服寿命,取得了一系列有益于理论和实践的研究成果。（1）通过全面研究岩土预应力锚固系统作用机理、类型及失稳机理,从动态观点对岩土预应力锚固系统及其长期稳定性进行了全新的定义和诠释,揭示出杆体材料应力腐蚀是决定其长期稳定性的根本因素,建立了岩土预应力锚固系统长期稳定性的总体研究框架,确定了研究的基本理论方向。（2）通过长期现场跟踪监测,揭示了锚索预应力在不同时期及不同影响因素作用下的变化特征和规律,降雨、昼夜温度变化、季节温度引起预应力产生近似闭合的“大循环”、“小循环”和“附加循环”波动变化特征,波动变化长期存在且滞后于影响因素的变化。通过采用流变力学理论研究与实际监测数据分析相结合的方法,构建了反映岩土体蠕变和预应力杆体材料松弛耦合作用的四参数本构模型,首次提出了预应力变化的“平稳衰减叠加波动”机理,建立了预测预应力长期变化的经验模型P=Ae^-a（t-b）+B+Dsin（w₂t+φ₂）+F+Ce^-ctsin（w₁t+φ₁）。（3）通过确定应力腐蚀的主要影响因素和正交组合分析,创造性地研制了模拟岩土环境中金属杆体材料应力腐蚀的室内足尺试验方法和装置。基于室内试验,确定了应力腐蚀的发展规律,首次建立了表征杆体材料应力腐蚀特征的定量公式C_l=p₁·x₁^p₂·e^-p₃x₂·(p₄+x₃^p₅),奠定了岩土预应力锚固系统司服寿命研究的理论基础。通过现场原位测试,首次揭示了实际工程环境中岩土预应力锚固系统应力腐蚀的典型分布和断面特征。利用现场原位试验数据对室内试验规律进行修正后,可用于预测实际岩土预应力锚固系统的司服寿命。（4）通过首次进行的在役预应力锚索现场原位足尺卸载与数值模拟的对比试验研究,揭示了单锚失效效应和岩土体内部应力调整规律,提出了不同位置锚索影响因子与间距的关系δ=f（L）。采用三维连续介质快速拉格朗日计算程序的数值模拟方法研究了群锚失效效应和稳定性丧失扩展规律,提出局部预应力锚固结构失效发展具有非单调连续性。当失效锚索达到一门槛值,岩土体纵向塑性区与临空面贯通,岩土体首先发生局部失稳。局部失稳所在的相对位置（距离）和数量对整体稳定性的影响具有显著区别。对于实际工程,得出当失效锚索多于8根或坡体表面塑性面积超过200m²时,发生局部失稳;主滑坡相邻级坡体同一纵断面同时发生局部失稳,或者发生能够相互贯通的多处（三处以上）局部失稳时将丧失整体稳定性等重要结论。（5）在提出岩土预应力锚固系统长期稳定性系统控制原理和专家预测复合控制方法的基础上,首次给出了考虑应力腐蚀并基于锚索失效数量门槛值最大的动态优化设计方法。全面分析研究了岩土预应力锚固系统稳定性的三种判据,创造性的建立了基于预应力变化规律和应力腐蚀规律的司服寿命确定方法,确定出实际工程的司服寿命为41年及不同部位的司服寿命范围。首次结合不同应力腐蚀量化特征和现场监测结果,提出了不同失效情况下的预警加固处理时机和针对不同预警失稳预应力锚固系统的加固处理方法。更多还原

【Abstract】 Based on literature research and practice,wherewith the field testing data of Jinan round city express-way,the long term stability of the geotechnical prestressed anchor system had been lucubrated entirely by utilizing such research means as theory analysis, field examination,indoor experiment,etc.By relating to the actual engineering,the application research about the study thought was carried out,then determining the service life of the actual engineering,obtaining a series of research production which were beneficial to the theory and practice.（1） Based on entire study of the operation mechanism,types and failure mechanism of geotechnical prestressed anchor system,the fire-new conception of the geotechnical prestressed anchor system and it’s long term stability were defined from dynamic viewpoint,it revealed that the stress corrosion of pole materials was the fundamental factor which would determine it’s long term stability.It constructed the collectivity research frame of long term stability for the geotechnical prestressed anchor system,ascertained the basic theory aspect of research.（2） By means of the long term tracking field-monitoring,it revealed the characteristic and regularity of the anchor cable prestress variation under the different influence factors and during different period.The prestress variation,which caused by the rain,temperature change day and night,temperature change every year,had obviously undulation characteristic,which was like approximatively close loop,these loop were called separately "the big recurrence","the small recurrence" and "the additive recurrence".The undulation variation chronically existed and lag behind the change of the influence factors.By means of combining the rehological mechanics and the actual monitoring rule,based on the Kelvin model and Burgers model,it found the four parameter constitutive model,which could reflect the coupled characteristic of the geotechnical creep and the relaxation of the pole materials.For the first time,it put forward the mechanism of "placidly attenuation superposing undulation variation",the experiential model was established by utilizing the formula "P=Ae^-a（t-b）+B+Dsin（w₂t+φ₂）+F+Ce^-ct sin（w₁t+φ₁）",which could forecast the long term prestress variation.（3） By means of making certain the principal influence factors and orthogonal combinatory analysis,it creatively manufactured the indoor full-scale experimentation technic and equipments,which could simulate the corrosion of the metal pole materials as actual geotechnical condition.Based on the indoor examination,it ascertained the development rule of the stress corrosion,it was first time to found the quantificational formula "C_l=p₁·x₁^p₂·e^-p₃x₂·(p₄+x₃^p₅)",which represented the stress corrosion rule, the theoretical foundation of the geotechnical prestressed anchor system service life research was established.In terms of the field-testing,it primarily revealed the typical distribution and cross-section characteristic of the stress corrosion in the actual circumstance.The indoor experiment rule was modified by utilizing field-testing data,it could be used to forecast the service life of the actual prestressed anchor engineering.（4） Through first contrastive research on the full-scale field-striping examination and the numerical simulation of the prestressed anchor cable,it revealed the invalidation effect of the single anchor cable and the regulative rule of interior stress,and put forward the formula "δ=f（L）",which expressed the relationship of the influence modulus and space on the different location.The invalidation effect of group anchor cable and the instability expanding rule was researched by means of the numerical simulation of the three dimension continua fast Lagrangian calculation method,it revealed that the quantity of the failure anchor cable reached a critical scale,interior longitudinal plastic zone would connect to face of slope,the local instability occurred. The relative distance and quantity of the local instability had obviously different influence on the integral stability.For actual engineering,it made such important conclusion as the part slope become unsteady when the failure anchor cable exceed to 8 or the plastic area of the slope surface exceed to 200 m²,when two local instability on the adjacent step of same vertical section occurred,or when more than three local instability could mutually joined up,the whole slope become unsteady.（5） It put forward the systemic control conception and combination control method of the geotechnical prestressed anchor system stability,it was first time to raise the dynamic optimizing design method based on the most critical scale due to the different combination of prestress and space,at the same time the stress corrosion was considered. It entirely analyzed the three criterion of the geotechnical prestressed anchor system stability,it creatively found the method of ascertaining service life based on the prestress variation rule and stress corrosion rule.The actual engineering service life would be 41 years,the different body of the slope would have different life range.By means of associating the different stress corrosion quantization characteristic and field-monitoring result,it was first time to put forward the warning and reinforcing opportunity for the different failure situation,and reinforcing measure which aimed at the different warning prestressed anchor system.更多还原