红层软岩高边坡多级框架锚杆地震动力响应及抗震设计分析

发布时间：2018-03-16 18:01

本文选题：红层软岩高边坡　切入点：多级框架锚杆　出处：《西南交通大学》2015年硕士论文　论文类型：学位论文

【摘要】：多级框架锚杆作为一种柔性支挡结构,广泛应用于红层软岩高边坡工程中。在地震作用下,该结构具有良好的加固效果。依托四川遂宁-资阳高速公路高边坡工程,采用数值模拟方法,分析了多级框架锚杆加固边坡的地震动力响应特征和失稳破坏模式,进而运用极限分析方法,推导分析了锚固边坡安全系数及相应的潜在滑面,并利用Newmark滑块分析法,得到了锚固边坡的永久位移。具体主要研究工作如下：(1)采用FLAC3D进行数值模拟,从PGA放大系数、坡体应力状态、最大剪应变增量、框架锚杆内力和水平位移的角度,分析了地震作用下多级高边坡的动力响应规律,以及多级框架锚杆的动力响应特征。揭示了地震波特性(幅值、频谱、持时)和竖向地震波对多级框架锚杆加固效果的影响规律。分析了锚杆长度、锚杆直径、锚杆倾角、框架梁间距等结构参数对锚固边坡抗震作用的影响,确定出最优锚杆长度为10m(0.1g幅值)和12m(0.2g幅值),锚杆存在最优倾角,框架梁走向(沿线路方向)间距取3m,横向(顺坡向)间距取2.5m。(2)采用极限分析上限定理,按坡体滑面为对数螺旋滑面和直线滑面进行能耗分析,推导出多级框架锚杆加固边坡的安全系数和屈服加速度的表达式。极限分析计算的安全系数与传统的传递系数—拟静力法计算的安全系数接近。锚固边坡的安全系数随着锚杆设计轴力的增大呈线性增大,随着锚杆倾角的增大呈近似线性减小,随着平台宽度的增大呈近似线性增大,随着黏聚力的增大呈线性增大,随着内摩擦角的增大呈近似指数增大,随着水平地震加速度系数的增大呈非线性减小,随着竖向地震加速度系数的增大呈近似线性增大。其中,锚杆设计轴力、平台宽度、坡体黏聚力、坡体内摩擦角和水平地震加速度系数对坡体的安全系数影响最大。(3)基于屈服加速度的计算,采用Newmark滑块分析法推导出多级框架锚杆加固边坡的永久位移的表达式,并与数值模拟和Ambraseys多元回归法对比,验证了其合理性。本研究得到的在地震作用下多级框架锚杆加固软岩高边坡的动力响应特征,以及锚固边坡安全系数和永久位移的计算方法方面的研究成果,可以为多级框架锚杆加固边坡工程的抗震设计提供理论指导和参考。
[Abstract]:As a kind of flexible retaining structure, multistage frame anchor is widely used in Yu Hong layer soft rock high slope engineering. Under the earthquake, the structure has good reinforcement effect. Relying on the high slope engineering of Suining Ziyang expressway in Sichuan province, In this paper, the seismic dynamic response and failure mode of multi-stage frame anchor reinforcement slope are analyzed by numerical simulation method, and the safety factor and corresponding potential slip surface of anchoring slope are deduced and analyzed by using limit analysis method. The permanent displacement of Anchorage slope is obtained by using Newmark slider analysis method. The main research work is as follows: 1) numerical simulation is carried out by FLAC3D. The maximum shear strain increment is obtained from PGA magnification factor, stress state of slope body, maximum shear strain increment. From the angle of internal force and horizontal displacement of frame anchor, the dynamic response law of multi-stage high slope under earthquake and the dynamic response characteristics of multi-stage frame anchor are analyzed, and the characteristics of seismic wave (amplitude, frequency spectrum) are revealed. The influence of structural parameters such as anchor length, anchor diameter, anchor inclination and frame beam spacing on the seismic behavior of anchoring slope is analyzed, such as the influence of seismic wave and vertical seismic wave on the reinforcement effect of multi-stage frame anchor rod, such as the length of anchor rod, the diameter of anchor rod, the angle of anchor rod, the spacing of frame beam, and so on. It is determined that the optimum length of anchor rod is 10 m / 0. 1 g) and 12 m / 0. 2 g / m), the anchor rod has an optimal inclination angle, the distance between frame beam direction (along the road) is 3 m, and the transverse (along slope) spacing is 2.5 m 路m ~ 2) the upper limit analysis theorem is adopted. The energy consumption analysis is carried out according to the logarithmic spiral surface and the linear surface of the slope body sliding surface. The expressions of safety factor and yield acceleration of slope strengthened by multi-stage frame anchor rod are derived. The safety factor calculated by limit analysis is close to that calculated by traditional transfer coeffcient-pseudostatic method. The safety of Anchorage slope is safe. The coefficient increases linearly with the increase of the axial force of anchor rod design. With the increase of Anchorage angle, the slope angle decreases approximately, the platform width increases linearly, the cohesive force increases linearly, and the angle of internal friction increases exponentially. With the increase of horizontal earthquake acceleration coefficient and the vertical seismic acceleration coefficient, the nonlinear decrease and the vertical seismic acceleration coefficient increase approximately linearly. Among them, the anchor rod design axial force, platform width, slope cohesion force, Based on the calculation of yield acceleration, the formula of permanent displacement of slope strengthened by multi-stage frame anchor rod is derived by Newmark sliding block analysis. Compared with numerical simulation and Ambraseys multivariate regression method, its rationality is verified. The dynamic response characteristics of multi-stage frame anchor reinforcement of soft rock high slope under seismic action are obtained in this paper. The research results of safety factor and permanent displacement of Anchorage slope can provide theoretical guidance and reference for seismic design of multi-stage frame anchor reinforcement slope engineering.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U416.14

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