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  本文選題：拱形明洞　切入點：落石沖擊　出處：《西南交通大學》2017年碩士論文　論文類型：學位論文

【摘要】：落石沖擊下拱形明洞結構的力學響應,與結構特征、落石條件及回填方式等眾多因素有關,受力機理復雜,只有將拱形明洞在落石沖擊下的結構受力機理研究清楚了,才能使結構設計更加安全和經濟,才可能使定性的經驗設計過渡到科學的可靠性設計上來。本文以我國新建時速200公里客貨共線鐵路雙線路塹式拱形明洞結構為研究對象,采用離散元和有限元相結合的方法對落石沖擊拱形明洞結構沖擊力大小影響因素、沖擊荷載及荷載效應開展研究。主要研究內容及成果如下:(1)離散元顆粒流數值計算模型的建立。采用離散元顆粒流PFC3D軟件,通過三軸試驗校準得到與材料宏觀物理力學性質一致的細觀參數,建立了不同坡度、落石下落高度、回填土厚度、落石重量和坡面性質條件下防落石拱形明洞結構數值計算模型。(2)運用正交設計理論,選擇正交表為L_(25)(5~6)的正交試驗方案,考察坡度、落石下落高度、回填土厚度、落石重量和坡面性質這五個因素對落石沖擊拱形隧道明洞結構的影響,以結構拱頂受到的沖擊峰值力作為評價指標,采用極差分析和方差分析進行了影響因素顯著水平檢驗。研究結果表明,回填土厚度對落石沖擊拱形隧道明洞結構的沖擊力影響最顯著。(3)采用ANSYS/LS-DYNA動力有限元仿真軟件,對落石沖擊下拱形明洞結構力學響應進行研究。首先,從落石與回填土之間的相互作用入手,比較了落石對回填土表面的沖擊力、由回填土傳遞到結構表面的沖擊土壓力(合力)以及拱頂表面受到的沖擊壓應力及其對應最大峰值之間的關系,提出應采用拱頂表面受到的沖擊壓應力作為落石沖擊荷載;其次,對落石沖擊荷載效應如結構的應力、應變、應變率、位移、加速度等響應進行了分析,對墻腳、仰拱底部地基反力進行了分析,分析得出拱頂是結構受力最不利部位,仰拱處基底反力響應滯后于墻腳基底反力響應;最后,進行了落石不同勢能下結構各部位峰值響應最大值的曲線擬合,擬合出響應趨勢曲線方程。
[Abstract]:The mechanical response of the open arch tunnel structure under the impact of falling stone is related to many factors, such as the structural characteristics, the condition of falling stone and the way of backfilling, and so on. The mechanical mechanism of the open arch tunnel under the impact of falling stone is studied clearly. In order to make the structure design safer and more economical, it is possible to make the qualitative experience design transition to the scientific reliability design. The method of discrete element and finite element method is used to influence the impact force of rock fall impact arch tunnel structure. The main contents and results of the research are as follows: 1) Establishment of numerical model of discrete element particle flow. PFC3D software of discrete element particle flow is used. Through triaxial test calibration, the mesoscopic parameters consistent with the macroscopic physical and mechanical properties of the material are obtained, and different slopes, falling height and backfill thickness are established. Under the condition of falling stone weight and slope property, the numerical calculation model of the structure of the open tunnel with the arch shape of anti-falling stone. (2) using the orthogonal design theory, the orthogonal test scheme of orthogonal test is selected as L25 / 25 / 5 / 5 / 6) to investigate the slope, the falling height and the thickness of the backfill soil, and to investigate the slope, the falling height of the falling rock, and the thickness of the backfill soil. The influence of rock falling weight and slope property on the structure of open tunnel with rock fall impact arch tunnel is studied. The peak impact force on the roof of the structure is taken as the evaluation index. The significant level test of influencing factors is carried out by means of range analysis and variance analysis. The results show that the thickness of backfill has the most significant influence on the impact force of the open tunnel structure of rock-falling arch tunnel. The ANSYS/LS-DYNA dynamic finite element simulation software is used. The structural mechanical response of the arch tunnel under the impact of falling stone is studied. Firstly, the impact force of the falling stone on the backfill surface is compared from the interaction between the falling stone and the backfill. The relationship between the impact earth pressure (resultant force) transferred from backfill to the structure surface and the impact compressive stress on the surface of the vault and its corresponding maximum peak value is proposed that the impact compressive stress on the surface of the vault should be used as the rock falling impact load. Secondly, the stress, strain, strain rate, displacement, acceleration response of rock fall impact load are analyzed, and the reaction force of the base of wall foot and invert arch is analyzed. It is concluded that the arch is the most unfavorable part of the structure. The counterforce response of the base at the inverted arch lags behind the counterforce response of the base of the wall. Finally, the curve fitting of the maximum peak response of each part of the structure under different potential energy is carried out, and the curve equation of the response trend is fitted.
【學位授予單位】：西南交通大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：U451;P642.2

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本文編號：1615438