發(fā)布時間：2018-02-04 07:05

  本文關鍵詞： 三臺階七步法 數(shù)值模擬 爆破振動 襯砌安全系數(shù) 敏感性　出處：《蘭州交通大學》2014年碩士論文　論文類型：學位論文

【摘要】：近年來伴隨著國民經濟的飛速發(fā)展，對鐵路運輸能力的要求也在不斷提升，大量單線鐵路隧道需要在旁邊增建二線隧道，這樣既可以提高既有鐵路的運輸能力又可節(jié)省建設投資，但是由于新建隧道與既有隧道間距往往很小，新建隧道施工過程中有可能損傷既有隧道結構進而影響運營安全。 本文依托西康二線新建銅羊溝隧道，通過現(xiàn)場檢測，理論分析和數(shù)值模擬來研究新建隧道施工對既有隧道結構的影響。主要工作內容和研究成果如下： (1)利用地質雷達對既有隧道襯砌質量進行檢測，通過雷達波圖像判別襯砌的厚度，脫空，不密實等缺陷情況，利用超聲回彈綜合法測混凝土強度，并且結合現(xiàn)場觀察判定既有隧道結構的健全度為C。 (2)運用MIDAS/GTS軟件建立三維模型，模擬在不同間距情況下新建隧道在三臺階七步法開挖過程中各特征測點位移變化規(guī)律、不同間距下中巖柱塑性區(qū)分布規(guī)律、既有隧道襯砌最大拉應力和最大壓應力變化規(guī)律，并對既有隧道軌道變形風險和襯砌破壞風險進行了確定。通過對既有隧道各斷面拱底位移值進行比較分析，將軌道風險等級確定為Ⅳ級，安全，，只需照常維護。新建隧道開挖方法安全可靠。 (3)通過現(xiàn)場振速監(jiān)測，結果表明：既有隧道襯砌結構振速未超過允許標準，對采集的爆破振動數(shù)據(jù)，利用最小二乘法回歸得到適用于該隧道Ⅳ級圍巖區(qū)域的爆破振動速度傳播與衰減規(guī)律的經驗公式。 (4)用ANSYS模擬新建隧道爆破振動對既有隧道結構的影響。當兩隧道間距為1D時，模擬得出的峰值振速值與實測值只相差0.072，速度時程曲線變化趨勢相近，說明數(shù)值模擬可靠。得到間距為1D時既有襯砌各特征點峰值振速分布和主應力峰值分布，迎爆側分布振速值大，迎爆側特征點振速要早于背爆側達到峰值。既有隧道的最大峰值振速和最大拉應力峰值，襯砌安全系數(shù)都在安全控制值內，說明當前新建隧道的爆破施工不會造成既有結構的破壞。 (5)用ANSYS模擬當間距變化時新建隧道在爆破施工中對既有隧道襯砌結構的影響規(guī)律，既有隧道襯砌迎爆測振速對間距的變化較敏感，通過回歸分析得到間距—峰值振速曲線，當間距大于2.5D時既有襯砌峰值振速變化趨于穩(wěn)定。 (6)對既有隧道結構最大峰值振速的影響因素進行敏感性分析，得到爆破荷載對峰值速度影響最大，通過控制炸藥量保證既有隧道結構峰值振速在安全允許值內。
[Abstract]:In recent years, with the rapid development of the national economy, the demand for railway transport capacity is also increasing. A large number of single-track railway tunnels need to be built next to the second-line tunnels. This can not only improve the transportation capacity of the existing railway but also save the construction investment. However, because the distance between the new tunnel and the existing tunnel is often very small, the construction process of the new tunnel may damage the existing tunnel structure and affect the operation safety. Based on the construction of Tongyanggou tunnel in Xikang No. 2 Line, this paper studies the influence of the new tunnel construction on the existing tunnel structure through field inspection, theoretical analysis and numerical simulation. The main work and research results are as follows:. (1) the quality of existing tunnel lining is detected by using ground penetrating radar, the thickness, void and density of lining are judged by radar wave image, and the strength of concrete is measured by the comprehensive method of ultrasonic rebound. And combined with on-site observation, the existing tunnel structure is judged to be the soundness of C. (2) using MIDAS/GTS software to establish 3D model, simulate the displacement change law of each characteristic measuring point in the excavation process of three-step and seven-step method under different spacing, and the distribution law of plastic zone of rock column under different spacing. The variation law of maximum tensile stress and maximum compressive stress of existing tunnel lining is determined, and the deformation risk of existing tunnel track and the risk of lining failure are determined. The displacement of arch bottom of each section of existing tunnel is compared and analyzed. The risk grade of track is determined to be grade 鈪

本文編號：1489653