锚固岩质边坡地震动力响应及锚固机理研究
发布时间：2018-09-05 06:25
【摘要】：边坡失稳往往会导致巨大的人员伤亡和财产损失,尤其在地震中,这一灾害将更加严重,故而提高边坡抗震性能的加固技术研究在工程实践中具有重要意义。边坡加固工程中,锚固技术因施工方便、经济,扰动小,效果好等特点,得到了成功而广泛的应用,但对边坡锚杆的加强机理仍缺乏深入的认识,锚杆对边坡动力性能的影响研究尤为匮乏。现有的研究还不能很好的解释地震作用下锚固岩质边坡的破坏机理,还没有公认合理的方法来判断边坡的动力稳定性,地震作用下边坡锚杆的锚固机理研究还不深入。因此研究锚固边坡的抗震性能,进而实现边坡锚固的优化设计已成为工程实践中急需解决的问题。 影响岩质边坡的稳定性的因素有很多,地震是最重要的外部影响因素之一,同一边坡在不同地震波的作用下其动力响应特征是不同的。岩质边坡的稳定性主要由岩体的结构控制,由于岩质边坡的结构形式多种多样,因此其破坏机理并不唯一。对于具有不同结构的岩质边坡,地震作用及锚杆的锚固作用也应该是不同的。锚杆的锚固作用主要应该是通过改善边坡岩体的结构特征,并体现在边坡的动力响应特征上。 分析边坡的动力响应是研究边坡的破坏机理、动力稳定性以及锚固机理的重要研究手段。本文采用FLAC3D对一锚固顺层岩质边坡进行了数值模拟研究,通过对地震作用下锚固岩质边坡的位移、加速度、锚杆轴力等动力响应分析,发现锚杆轴力与其附近围岩的应变直接相关,并利用响应加速度傅立叶谱研究了锚固作用对边坡岩体宏观性能的影响。结果显示,边坡的相对位移时程曲线不能直接作为边坡是否破坏的判据,应进一步进行应变分析判断边坡是否破坏；锚杆能显著减小边坡的应变值,提高边坡岩体间的变形协调能力,增强边坡的抗震性能,岩体的应变越大,锚杆的锚固效果越好；边坡的永久位移是由较大地震加速度激发的,且在地震作用过程中存在累积效应；锚固作用能改善岩体的材料属性,但效果不明显。由于动荷载作用对边坡的名义剪应变和等效拉应变具有放大作用,故可根据“荷载激励法”来确定边坡破坏面的位置。 通过输入不同的地震波,研究了波型以及振幅、频率及持时等地震动参数对同一顺层岩质边坡的地震动力响应的影响,得到了不同地震动参数对边坡动力响应的影响规律。虽然不同地震作用下,同一边坡的动力响应不同,但岩层交界面是动力响应特征的分界面,边坡的结构特征是边坡动力响应特性的主导因素,锚杆对岩质边坡的锚固作用主要是改变或改善了边坡的结构特征。因此,复杂的边坡地震动力稳定性问题可回归到边坡的结构特征上。 为进一步探讨边坡锚杆在动载下的锚固作用与锚固机理,采用几种岩质边坡中常见的岩体结构元件破坏模型,探讨了地震力和锚固作用对不同岩体模型稳定性的影响。分析边坡锚杆系统在地震作用下力的传递过程,提出了一种单锚杆锚固体系的动力简化分析模型,并对模型的合理性进行了验证。利用提出的动力简化模型,基于锚杆荷载分布解析解对含有单结构面和二结构面的岩体模型进行了锚杆荷载分布的求解,讨论了岩体、锚杆的材料参数以及不同地震作用状态对锚杆荷载分布的影响,从受力分析的角度探讨了锚杆的锚固机理,并提出由多组结构面控制的岩质边坡的优化锚固方式。 最后以石窟崖体作为工程案例进行分析。对于石窟崖体这种特殊的岩质边坡进行动力响应计算时,不可忽略其复杂的几何特征。为建立较为精细的石窟崖体3维模型,使用全站仪,利用激光测距的原理可获取石窟崖体表面的点云坐标,然后通过CAE软件进行辅助建模。基于边坡动力响应数值分析方法,对石窟崖体进行地震动力响应分析,得到了具有复杂几何特征的石窟崖体的动力响应特征,讨论了石窟的开凿对崖体动力响应的影响,并分析了地震作用下石窟的破坏模式及其原因。使用曾在石窟加固中使用过的小锚杆对模型上部岩体进行加固,并对锚固石窟模型进行动力计算,分析了锚固崖体的动力响应特征,探讨了小锚杆锚固的抗震性能并给出了工程建议。 本文的研究有助于进一步认识锚固岩质边坡的地震动力响应规律,地震稳定性以及动力作用下边坡锚杆的锚固作用和锚固机理,为岩质边坡的锚固设计提供了一定的理论依据。
[Abstract]:Slope instability often leads to huge casualties and property losses, especially in earthquakes, this disaster will be more serious, so the study of reinforcement technology to improve the seismic performance of slope is of great significance in engineering practice. It has been widely used, but the reinforcement mechanism of slope bolt is still lack of in-depth understanding, and the influence of bolt on the dynamic performance of slope is particularly scarce. The research on anchorage mechanism of anchor bolt in lower slope is not yet in-depth, so it is urgent to study the seismic performance of anchored slope and realize the optimal design of anchorage in slope.
There are many factors affecting the stability of rock slope, and earthquake is one of the most important external factors. The dynamic response characteristics of the same slope are different under the action of different seismic waves. Only. For rock slopes with different structures, seismic action and anchorage action of bolts should be different. Anchorage action of bolts should be mainly through improving the structural characteristics of rock slopes, and reflected in the dynamic response characteristics of slopes.
Analyzing the dynamic response of the slope is an important means to study the failure mechanism, dynamic stability and anchorage mechanism of the slope. In this paper, FLAC3D is used to simulate a rock slope with anchorage bedding. By analyzing the dynamic response of displacement, acceleration and axial force of the anchored rock slope under earthquake, the anchor is found. The results show that the relative displacement time-history curve of the slope can not be directly used as the criterion of whether the slope is destroyed, and further strain analysis should be carried out to determine whether the slope is destroyed. The larger the strain of the rock mass, the better the anchorage effect of the bolt; the permanent displacement of the slope is excited by the greater seismic acceleration, and there is cumulative effect in the process of earthquake; the anchorage can improve the material properties of the rock mass. Because the dynamic load can amplify the nominal shear strain and the equivalent tensile strain of the slope, the position of the failure surface of the slope can be determined according to the load excitation method.
By inputting different seismic waves, the effects of wave type, amplitude, frequency and duration on the seismic dynamic response of the same bedding rock slope are studied, and the influence of different seismic parameters on the dynamic response of the slope is obtained. It is the interface of the dynamic response characteristics, and the structural characteristics of the slope are the dominant factors of the dynamic response characteristics of the slope. The anchoring effect of the bolt on the rock slope is mainly to change or improve the structural characteristics of the slope.
In order to further explore the anchorage action and anchorage mechanism of slope bolts under dynamic loading, several common failure models of rock mass structural elements in rock slopes are used to study the influence of seismic force and anchorage action on the stability of different rock mass models. The simplified dynamic analysis model of the anchorage system is established and the rationality of the model is verified. Based on the simplified dynamic model and the analytical solution of the load distribution of the anchorage bolt, the load distribution of the rock mass model with single structural plane and two structural planes is solved. The rock mass, the material parameters of the anchor bolt and the different seismic behavior are discussed. The effect of state on the load distribution of rock bolt is discussed. The anchorage mechanism of rock bolt is discussed from the point of force analysis. The optimal anchorage method of rock slope controlled by multiple structural planes is proposed.
Finally, the grotto cliff is taken as an engineering case to analyze. When calculating the dynamic response of the grotto cliff, the complex geometric characteristics can not be ignored. In order to establish a more precise 3D model of the grotto cliff, the point cloud coordinates on the surface of the grotto cliff can be obtained by using the total station and the principle of laser ranging. Based on the numerical analysis method of slope dynamic response, the dynamic response characteristics of grotto cliff with complex geometric characteristics are obtained. The influence of grotto excavation on the dynamic response of cliff body is discussed, and the failure mode of grotto under earthquake is analyzed. The upper rock mass of the model is strengthened with small bolts which have been used in grotto reinforcement. The dynamic response characteristics of the anchored cliff are analyzed by dynamic calculation of the anchored grotto model. The seismic performance of the anchored cliff is discussed and the engineering suggestions are given.
The study of this paper is helpful to further understand the law of seismic dynamic response of anchored rock slope, seismic stability, anchorage action and anchorage mechanism of rock bolt under dynamic action, and provides a theoretical basis for anchorage design of rock slope.
【学位授予单位】：兰州大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TU435;TU476
本文编号：2223458
[Abstract]:Slope instability often leads to huge casualties and property losses, especially in earthquakes, this disaster will be more serious, so the study of reinforcement technology to improve the seismic performance of slope is of great significance in engineering practice. It has been widely used, but the reinforcement mechanism of slope bolt is still lack of in-depth understanding, and the influence of bolt on the dynamic performance of slope is particularly scarce. The research on anchorage mechanism of anchor bolt in lower slope is not yet in-depth, so it is urgent to study the seismic performance of anchored slope and realize the optimal design of anchorage in slope.
There are many factors affecting the stability of rock slope, and earthquake is one of the most important external factors. The dynamic response characteristics of the same slope are different under the action of different seismic waves. Only. For rock slopes with different structures, seismic action and anchorage action of bolts should be different. Anchorage action of bolts should be mainly through improving the structural characteristics of rock slopes, and reflected in the dynamic response characteristics of slopes.
Analyzing the dynamic response of the slope is an important means to study the failure mechanism, dynamic stability and anchorage mechanism of the slope. In this paper, FLAC3D is used to simulate a rock slope with anchorage bedding. By analyzing the dynamic response of displacement, acceleration and axial force of the anchored rock slope under earthquake, the anchor is found. The results show that the relative displacement time-history curve of the slope can not be directly used as the criterion of whether the slope is destroyed, and further strain analysis should be carried out to determine whether the slope is destroyed. The larger the strain of the rock mass, the better the anchorage effect of the bolt; the permanent displacement of the slope is excited by the greater seismic acceleration, and there is cumulative effect in the process of earthquake; the anchorage can improve the material properties of the rock mass. Because the dynamic load can amplify the nominal shear strain and the equivalent tensile strain of the slope, the position of the failure surface of the slope can be determined according to the load excitation method.
By inputting different seismic waves, the effects of wave type, amplitude, frequency and duration on the seismic dynamic response of the same bedding rock slope are studied, and the influence of different seismic parameters on the dynamic response of the slope is obtained. It is the interface of the dynamic response characteristics, and the structural characteristics of the slope are the dominant factors of the dynamic response characteristics of the slope. The anchoring effect of the bolt on the rock slope is mainly to change or improve the structural characteristics of the slope.
In order to further explore the anchorage action and anchorage mechanism of slope bolts under dynamic loading, several common failure models of rock mass structural elements in rock slopes are used to study the influence of seismic force and anchorage action on the stability of different rock mass models. The simplified dynamic analysis model of the anchorage system is established and the rationality of the model is verified. Based on the simplified dynamic model and the analytical solution of the load distribution of the anchorage bolt, the load distribution of the rock mass model with single structural plane and two structural planes is solved. The rock mass, the material parameters of the anchor bolt and the different seismic behavior are discussed. The effect of state on the load distribution of rock bolt is discussed. The anchorage mechanism of rock bolt is discussed from the point of force analysis. The optimal anchorage method of rock slope controlled by multiple structural planes is proposed.
Finally, the grotto cliff is taken as an engineering case to analyze. When calculating the dynamic response of the grotto cliff, the complex geometric characteristics can not be ignored. In order to establish a more precise 3D model of the grotto cliff, the point cloud coordinates on the surface of the grotto cliff can be obtained by using the total station and the principle of laser ranging. Based on the numerical analysis method of slope dynamic response, the dynamic response characteristics of grotto cliff with complex geometric characteristics are obtained. The influence of grotto excavation on the dynamic response of cliff body is discussed, and the failure mode of grotto under earthquake is analyzed. The upper rock mass of the model is strengthened with small bolts which have been used in grotto reinforcement. The dynamic response characteristics of the anchored cliff are analyzed by dynamic calculation of the anchored grotto model. The seismic performance of the anchored cliff is discussed and the engineering suggestions are given.
The study of this paper is helpful to further understand the law of seismic dynamic response of anchored rock slope, seismic stability, anchorage action and anchorage mechanism of rock bolt under dynamic action, and provides a theoretical basis for anchorage design of rock slope.
【学位授予单位】：兰州大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TU435;TU476
【参考文献】
相关博士学位论文 前2条
1 刘亚群;动荷载作用下层状结构岩体边坡变形破坏机理与安全研究[D];中国科学院研究生院（武汉岩土力学研究所）;2009年
2 杨为民;锚杆对断续节理岩体的加固作用机理及应用研究[D];山东大学;2009年
，本文编号：2223458
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