【作者】 宋志坚；

【导师】 肖世国；

【作者基本信息】 西南交通大学 ， 岩土工程， 2011， 硕士

【摘要】 根据对四川省内的由2008年5.12汶川8.0级地震造成的路堑边坡震害进行的调查,归纳分析了锚固边坡的震害情况。在通过室内直剪试验获得锚固体与岩体界面的抗剪强度参数的基础上,结合锚固边坡震害调查结果,对预应力锚索结构与边坡岩土体的动力相互作用机制进行了计算分析。本文的主要工作内容与结果如下：1)通过对岩质路堑边坡的震害情况的调查分析,发现采用锚固结构加固的边坡具有较好的抗震性能。2)通过直剪试验模拟了砂浆和岩石粘结面的剪切破坏过程；分析了峰值强度的影响因素及砂灰比对砂浆岩石粘结强度的影响规律,得到残余内摩擦角和残余粘聚力分别在砂灰比为0.75、0.50时取得较大值；得到砂浆与三种常见岩石的粘结强度参数。3)用拟静力法推导了平面滑动和圆弧滑动模式的边坡在水平地震作用下的预应力锚索内力的计算公式形如T=Af(kei)+B,得到随着水平地震影响系数的增加,锚索的锚拉力呈线性增长的变化特征。利用弹性理论推导了锚索锚固段剪应力分布公式及最大剪应力出现的位置与其影响因素,得到岩体越软,剪应力分布范围越大峰值越小；地震过程中锚固段未破坏时,最大剪应力位置保持不变(zτmax=(?)1/b,b为与锚固体直径及变形参数有关的计算参数)；岩体泊松比越小、岩体与锚固体弹性模量比值越大,锚固段剪应力峰值位置越浅。4)利用理论分析和数值模拟方法讨论了锚固结构动力作用机制与特征,得到在地震条件下关于锚固结构和边坡的动力响应规律如下：①锚固结构内力会增加,平均增加幅度约为60%,在地震过程中会加大对边坡的锚固作用；对降低坡脚处的剪应变、限制坡面位移、维护边坡稳定发挥了重要作用；锚固结构可与坡体发生很好地变形协调,改善边坡岩土体的应力状态,提高边坡中潜在滑动面或软弱结构面的抗剪强度,有利于坡体稳定。锚固结构受竖向地震作用的影响较小。②就整体而言,随着岩质边坡高程的增加,水平加速度、速度、位移有垂直放大的规律；但沿坡面向上PGA放大系数呈先增大后减小规律；③竖向地震作用会增大坡顶、坡脚处的剪应变,降低坡体的安全系数,但对坡体主应力、放大系数、锚固结构内力影响不大。本文在锚固边坡的震害调查、锚固结构与岩体界面抗剪强度参数、预应力锚索结构与边坡的动力相互作用分析方法及作用机制方面的研究工作,有助于进一步认识在强震条件下边坡锚固结构的力学作用特征,可为实际工程提供理论参考。更多还原

【Abstract】 Based on the investigation of cutting slope damage caused by the Wenchuan 8.0 earthquake in Sichuan Province, the author mainly summarizes the anchored cutting slope earthquake damage. On the basis of getting the shear strength parameters of interface between mortar and rock through direct shear tests, and in conjunction with the results of anchored cutting slope earthquake damage investigation, dynamic interaction mechanism of cutting rock slope with prestressed anchor cable structure is calculated and analyzed. The main work content and results are as follows:1) The analysis of the cutting slope earthquake damage investigation shows that slope reinforced by anchor structure has better seismic performance.2) Through direct shear tests, simulation of the shear failure process of bonding interface between mortar and rock is carried out. Analysis of influencing factors of the peak strength and the influencing rule of sand cement ratio on shear bond strength of mortar to rock is carried out. The residual angle and the residual cohesion are greater while in the sand cement ratio of 0.75 and 0.50 respectively. Shear strength parameters of mortar to three types of rocks are obtained.3) In situations of considering the horizontal earthquake in plane and arc sliding destruction, the cable axial force formula is derived such as T=Af(kcl)+B by pseudo-static method which shows that cable axial increases linearly with the increase of horizontal seismic effect coefficient.With elastic theory, the paper deduces the anchoring section grout shear stress distribution formula and the location and influencing factors of maximum shear stress appears.The formula shows that the softer the rock is, the greater the shear stress distribution is and the smaller the peak shear stress is. The conclusion is obtained that under the earthquake anchoring section shear stress peak position remains unchanged while plastic—failure does not occur(zrmax=(?)V1/b, b is a parameter related to diameter, elastic module, and Possion’ ratio of anchorage section).The smaller the rock Poisson’s ratio is and the greater the ratio of rock’s and anchoring section’s elastic modulus is, the more shallow the anchoring section peak shear stress position is.4) By using the theoretical calculation and the numerical analysis method to analyze the dynamic mechanism and characteristics of anchor structure, the paper gets the dynamic responses of anchor structure and slop which are as follows:①The internal force of anchor structure will increase, it increases by 60% or so in this paper example. The anchor structure plays an important role in reducing the shear strain increment at the toe of slope, limiting slope surface displacement, maintaining the stability of slope. The structure can well coordinate deformation with slope in the earthquake process, fully mobilize their own strength and steady ability of slope masses, and improve the slope masses stress state, which can be helpful to increase shear strength of potential sliding surface and weak structure plane in an earthquake. Compared to the horizontal seismic wave, corresponding vertical wave has little effect on the anchor structure.②On the whole, with the increase of elevation, the amplification factor of horizontal acceleration, velocity, displacement increases. But the PGA amplification coefficient first increases, then decreases upwards along the slope surface.③The vertical earthquakes will increase the shear strain at top of slope and toe of slope, reduce the safety factor of slope, but have little effect on the principal stress, amplification factor and internal force of anchor structure.In this paper, the research contains anchored slope earthquake damage investigation, shear strength parameters of bond interface between anchor structure and rock, dynamic mechanism of interaction between cutting rock slope with prestressed anchor cable structure during strong earthquakes. The research results are helpful to further understanding of the mechanical mechanism of slope with anchor structure during strong earthquakes, and can provide theoretical references for practical projects.更多还原