【摘要】：邊坡失穩(wěn)往往會導(dǎo)致巨大的人員傷亡和財產(chǎn)損失,尤其在地震中,這一災(zāi)害將更加嚴(yán)重,故而提高邊坡抗震性能的加固技術(shù)研究在工程實踐中具有重要意義。邊坡加固工程中,錨固技術(shù)因施工方便、經(jīng)濟(jì),擾動小,效果好等特點,得到了成功而廣泛的應(yīng)用,但對邊坡錨桿的加強(qiáng)機(jī)理仍缺乏深入的認(rèn)識,錨桿對邊坡動力性能的影響研究尤為匱乏�，F(xiàn)有的研究還不能很好的解釋地震作用下錨固巖質(zhì)邊坡的破壞機(jī)理,還沒有公認(rèn)合理的方法來判斷邊坡的動力穩(wěn)定性,地震作用下邊坡錨桿的錨固機(jī)理研究還不深入。因此研究錨固邊坡的抗震性能,進(jìn)而實現(xiàn)邊坡錨固的優(yōu)化設(shè)計已成為工程實踐中急需解決的問題。 影響巖質(zhì)邊坡的穩(wěn)定性的因素有很多,地震是最重要的外部影響因素之一,同一邊坡在不同地震波的作用下其動力響應(yīng)特征是不同的。巖質(zhì)邊坡的穩(wěn)定性主要由巖體的結(jié)構(gòu)控制,由于巖質(zhì)邊坡的結(jié)構(gòu)形式多種多樣,因此其破壞機(jī)理并不唯一。對于具有不同結(jié)構(gòu)的巖質(zhì)邊坡,地震作用及錨桿的錨固作用也應(yīng)該是不同的。錨桿的錨固作用主要應(yīng)該是通過改善邊坡巖體的結(jié)構(gòu)特征,并體現(xiàn)在邊坡的動力響應(yīng)特征上。 分析邊坡的動力響應(yīng)是研究邊坡的破壞機(jī)理、動力穩(wěn)定性以及錨固機(jī)理的重要研究手段。本文采用FLAC3D對一錨固順層巖質(zhì)邊坡進(jìn)行了數(shù)值模擬研究,通過對地震作用下錨固巖質(zhì)邊坡的位移、加速度、錨桿軸力等動力響應(yīng)分析,發(fā)現(xiàn)錨桿軸力與其附近圍巖的應(yīng)變直接相關(guān),并利用響應(yīng)加速度傅立葉譜研究了錨固作用對邊坡巖體宏觀性能的影響。結(jié)果顯示,邊坡的相對位移時程曲線不能直接作為邊坡是否破壞的判據(jù),應(yīng)進(jìn)一步進(jìn)行應(yīng)變分析判斷邊坡是否破壞；錨桿能顯著減小邊坡的應(yīng)變值,提高邊坡巖體間的變形協(xié)調(diào)能力,增強(qiáng)邊坡的抗震性能,巖體的應(yīng)變越大,錨桿的錨固效果越好；邊坡的永久位移是由較大地震加速度激發(fā)的,且在地震作用過程中存在累積效應(yīng)；錨固作用能改善巖體的材料屬性,但效果不明顯。由于動荷載作用對邊坡的名義剪應(yīng)變和等效拉應(yīng)變具有放大作用,故可根據(jù)“荷載激勵法”來確定邊坡破壞面的位置。 通過輸入不同的地震波,研究了波型以及振幅、頻率及持時等地震動參數(shù)對同一順層巖質(zhì)邊坡的地震動力響應(yīng)的影響,得到了不同地震動參數(shù)對邊坡動力響應(yīng)的影響規(guī)律。雖然不同地震作用下,同一邊坡的動力響應(yīng)不同,但巖層交界面是動力響應(yīng)特征的分界面,邊坡的結(jié)構(gòu)特征是邊坡動力響應(yīng)特性的主導(dǎo)因素,錨桿對巖質(zhì)邊坡的錨固作用主要是改變或改善了邊坡的結(jié)構(gòu)特征。因此,復(fù)雜的邊坡地震動力穩(wěn)定性問題可回歸到邊坡的結(jié)構(gòu)特征上。 為進(jìn)一步探討邊坡錨桿在動載下的錨固作用與錨固機(jī)理,采用幾種巖質(zhì)邊坡中常見的巖體結(jié)構(gòu)元件破壞模型,探討了地震力和錨固作用對不同巖體模型穩(wěn)定性的影響。分析邊坡錨桿系統(tǒng)在地震作用下力的傳遞過程,提出了一種單錨桿錨固體系的動力簡化分析模型,并對模型的合理性進(jìn)行了驗證。利用提出的動力簡化模型,基于錨桿荷載分布解析解對含有單結(jié)構(gòu)面和二結(jié)構(gòu)面的巖體模型進(jìn)行了錨桿荷載分布的求解,討論了巖體、錨桿的材料參數(shù)以及不同地震作用狀態(tài)對錨桿荷載分布的影響,從受力分析的角度探討了錨桿的錨固機(jī)理,并提出由多組結(jié)構(gòu)面控制的巖質(zhì)邊坡的優(yōu)化錨固方式。 最后以石窟崖體作為工程案例進(jìn)行分析。對于石窟崖體這種特殊的巖質(zhì)邊坡進(jìn)行動力響應(yīng)計算時,不可忽略其復(fù)雜的幾何特征。為建立較為精細(xì)的石窟崖體3維模型,使用全站儀,利用激光測距的原理可獲取石窟崖體表面的點云坐標(biāo),然后通過CAE軟件進(jìn)行輔助建模�；谶吰聞恿憫�(yīng)數(shù)值分析方法,對石窟崖體進(jìn)行地震動力響應(yīng)分析,得到了具有復(fù)雜幾何特征的石窟崖體的動力響應(yīng)特征,討論了石窟的開鑿對崖體動力響應(yīng)的影響,并分析了地震作用下石窟的破壞模式及其原因。使用曾在石窟加固中使用過的小錨桿對模型上部巖體進(jìn)行加固,并對錨固石窟模型進(jìn)行動力計算,分析了錨固崖體的動力響應(yīng)特征,探討了小錨桿錨固的抗震性能并給出了工程建議。 本文的研究有助于進(jìn)一步認(rèn)識錨固巖質(zhì)邊坡的地震動力響應(yīng)規(guī)律,地震穩(wěn)定性以及動力作用下邊坡錨桿的錨固作用和錨固機(jī)理,為巖質(zhì)邊坡的錨固設(shè)計提供了一定的理論依據(jù)。
[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.
【學(xué)位授予單位】：蘭州大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2014
【分類號】：TU435;TU476

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本文編號：2223458