基于可靠性的锚杆抗滑桩全局优化设计研究

【作者】 杨向军；

【导师】 门玉明；

【作者基本信息】 长安大学 ， 地质工程， 2005， 硕士

【摘要】 锚杆—抗滑桩是用于加固坡体和治理滑坡的一种非常有效的工程措施。它是在抗滑桩的顶部或适当位置设置锚杆,给抗滑桩增加一个拉力,使抗滑桩的受力和内力分布更加合理,因此可以减小抗滑桩的截面尺寸,节约大量的工程投资。在国内,锚杆抗滑桩的应用数量非常大,但对其计算方法和设计理论的研究明显滞后于工程实践。为此,许多学者都在致力于锚杆—抗滑桩的理论研究工作,并取得了一定的成绩。目前,锚杆—抗滑桩的理论研究主要是在确定性分析基础上进行的,然而岩土体本身、岩土体与结构相互作用的特性决定描述它们的参数具有非常大的变异性,再加上计算模式的不确定性,对这些因素的确定性处理会造成计算结果很大的误差。因此,更加合理的计算应该是用概率统计的数学手段来解决问题。 本文基于锚杆—抗滑桩的研究现状,在可靠性分析的基础上,对锚杆—抗滑桩结构系统的全局优化问题进行了研究。 论文首先简单的介绍了土木工程可靠性分析的发展历程、可靠性分析的基本理论。依据目前锚杆—抗滑桩的研究成果,介绍了锚杆—抗滑桩的结构力学计算方法,该方法综合考虑了抗滑桩和锚杆受力后的协调变形关系,因此它是现阶段理论计算中最合理的计算方法。 通过综合比较,鉴于目前描述岩土体参数的特征以及这些参数的统计分析资料,选择岩土体的粘聚力C、内摩角φ和混凝土轴心抗压强度作为随机变量,其余计算参数作为确定值;进行可靠性分析和计算时,采用对问题的维数不敏感的蒙特卡罗数值模拟,通过混合同余法产生伪随机数,根据正态分布随机变量的抽样产生随机变量的抽样值。因为工程设施的可靠性是小概率事件,对于小概率事件的蒙特卡洛模拟,如果运用直接蒙特卡洛方法会造成计算工作量的过大,为了节约计算费用,本文采用减小方差效果非常好的重要抽样法产生随机变量。编制了程序对锚杆—抗滑桩的可靠性进行数字模拟。 在分析锚杆—抗滑桩系统可靠性的基础上,将系统分解为锚杆和抗滑桩两个一级子系统,将抗滑桩分解为三个二级子系统,根据等分配原理进行了可靠度的分配,并建立了锚杆—抗滑桩系统可靠度的最优分配模式。 在MS Excel环境下,利用Excel强大的计算分析功能,建立了锚杆—抗滑桩更多还原

【Abstract】 Anti-slide pile with anchored rod is an efficient method to strengthen and treat landslide. Anchored rod at the top of or other appropriate position of anti-slid pile can supply a tension for anti-slid pile, make the applied loads and the stresses of it distribute more rational (reasonable), thus, the dimension of anti-slid pile can be reduced. As a result the cost of it can be reduced largely. In the nation, anti-slide pile with anchored rod is applied widely, however, its calculation method and design theory are behind of its application in engineering. For’this, many scholars have been dedicated to research the theory about it. At the same time, many achievements have been made in theoretical research on it. At present, theoretical research of anti-slid pile with anchored rod is based on the definite analysis. However, the parameters described the soils and rocks are variable because of the properties of soil and rock and the interaction of soil and rock and structure. In addition, the calculation models are also uncertain. Therefore, the calculated results have some errors. The more reasonable method may be based on probability statistics.The paper intended to research the global optimization problem of the structural system of anti-slid pile with anchored rod based on the reliability analysis.First, the paper briefly introduced the history and basic theory of reliability analysis in civil engineering. Based on the achievements on anti-slid pile with anchored rod, the calculated method on structure mechanics was introduced. Since it considers the compatibility of deformation between the anti-pile and the anchored rod, it is the most appropriate method of theoretical calculation at the present time.Through compared synthetically, cohesion, internal angle of soil and axial compression of concrete are selected as random parameters depended on the characteristics of parameters described soils and rocks and the statistic analysis data , other parameters are taken as definite value. Monte Carlo numerical simulation, which is not sensitive to dimension, was applied. When making reliability analysis and calculation, pseudo-random numbers are produced through mixed congruence method, random variable values are generated by random sampling on basis of normaldistribution. In order to reduce the cost, important random sampling method, which is very efficient to reduce variance, was used to produce random variable. The reliability of anti-slid pile with anchored rod was simulated used Visual Basic program.Based on the analysis of reliability of it, the system of anchored rod -anti-slid pile was break up into anchored rod and anti-slid pile, which are two sub-systems. Anti-slid pile was break up into three the second grade system. The optimization allocation model was constructed on the basis of the equable allocation principle of reliability.A math model of anti-slid pile with anchored rod, which has optimization objective function and restraint condition, was constructed used the powerful calculation and analysis performance of Excel. The global optimization of anti-slid pile was performed used "plan solution".Finally, take the BaoTa Montain landslide as an engineering case, the reliability of design schemes were analyzed used the research results of this paper, optimization design was made and the practicability of the research results were examined by compared the cost of the three schemes which are the conventional scheme, the anti-slid pile with anchored rod schemes before optimized and after optimized one, respectively.更多还原