岩溶公路隧道施工及运营安全性研究

发布时间：2018-08-22 07:44

【摘要】：本文依托贵州省六盘水市小坝田岩溶公路隧道，结合理论分析、数值模拟，分别从隧道静力开挖、爆破施工、地震响应、车辆荷载作用4各方面对岩溶公路隧道施工及运营情况下围岩的稳定性和支护结构的安全性进行了研究，主要研究内容及其结论如下： (1)采用ANSYS有限元软件模拟了小坝田岩溶公路隧道台阶法施工，并结合围岩应力、围岩塑性区、衬砌变形、衬砌应力、衬砌安全系数以及由Griffith准则提出的衬砌开裂系数等分析了施工过程中小坝田隧道围岩的稳定性和衬砌结构安全性，上述结果均满足规范要求，说明小坝田岩溶公路隧道在开挖过程中围岩稳定，支护结构安全。 (2)基于小坝田隧道的模型和工程地质条件，分析了不同分布部位的溶洞对隧道围岩稳定性和支护结构安全性的影响规律，从围岩塑性区、特征点位移、衬砌应力、衬砌安全系数等方面确定了溶洞位于隧道侧部是对围岩和衬砌支护结构影响最大的最不利分布部位。 (3)根据侧部溶洞是对围岩和衬砌支护结构影响最大的最不利位置，引入洞径比λR和间距比KR，按数值试验的方法分析了溶洞与隧道距离的变化和溶洞大小的变化对隧道围岩稳定性和支护结构安全性的影响规律。溶洞对隧道的影响随洞径比λR的增大而增大，随间距比KR的增大而减小。洞径比λR小于0.217时，溶洞对隧道影响趋近于零，隧道设计和施工时可以不予考虑。间距比KR大于1.419时，溶洞对隧道的影响程度变化趋于稳定。 (4)查阅相关文献，以爆破振动速度、溶洞各质点应力极值、爆破破坏指数BDI作为小坝田隧道爆破施工过程中溶洞是否安全的评判标准，运用ANSYS有限元软件对小坝田隧道爆破施工进行了模拟，并以围岩损伤断裂准则得出最大安全振动速度13.74cm/s、围岩动抗拉强度2.13Mpa，围岩动抗压强度23.25Mpa、爆破破坏指数BDI"f1.0评判小坝田隧道爆破施工过程中溶洞的稳定性，计算结果均满足规范要求，说明小坝田岩溶公路隧道爆破施工时溶洞不会发生失稳破坏。 (5)基于小坝田隧道的动力计算模型和工程地质条件，从最大振动速度、最大抗拉压应力、最大爆破破坏指数等角度分别分析了爆破施工对不同分布部位溶洞（溶洞位于隧道顶部、底部、侧部）的影响，得到溶洞位于隧道底部是爆破施工对溶洞影响最大的最不利分布部位。 (6)根据溶洞位于隧道底部是爆破施工对溶洞影响最大的最不利分布部位，从溶洞与隧道间距出发，拟合得到了溶洞与隧道间距与最大振动速度的关系为v=88.187x-0.797，并确定了隧道与溶洞爆破施工的安全间距为1.15D。 (7)选用基线校正和滤波后的EL-Centro波，采用ANSYS有限元软件对小坝田隧道动力计算模型施加EL-Centro波水平加速度荷载，分析了地震荷载作用下隧道衬砌和溶洞特征点的振动速度规律，并以衬砌和溶洞的最大拉压应力和应力增量判断衬砌和溶洞的安全性。结果表明：在地震作用下，衬砌最大拉应力为0.752Mpa，最大压应力为2.45Mpa，溶洞周边各质点最大拉应力为0.169Mpa，最大压应力为2.126Mpa，上述结果均满足规范要求，说明小坝田隧道在地震作用下不会发生拉、压裂破坏。 (8)分别建立溶洞位于隧道顶部、侧部和底部的有限元模型，对模型施加EL-Centro波水平加速度荷载，从隧道衬砌与溶洞各特征点的位移、速度和衬砌与溶洞的环向主应力极值、主应力增量最大值进行比较，得出在地震作用下，，溶洞位于隧道侧部是溶洞分布的最不利分布部位。 (9)以小坝田隧道动力计算模型，将车辆荷载考虑成激振力函数，采用ANSYS有限元软件模拟了车辆荷载作用下岩溶公路隧道的动力响应，从衬砌和溶洞最大振动速度、应力极值和应力增量角度判断了车辆荷载作用下岩溶公路隧道衬砌结构和溶洞安全性。结果表明：车辆荷载对隧道和溶洞的影响很小，在车辆荷载作用，隧道结构和溶洞不会发生失稳破坏。
[Abstract]:Based on the karst highway tunnel in Xiaobatian, Liupanshui City, Guizhou Province, combined with theoretical analysis and numerical simulation, this paper studies the stability of surrounding rock and the safety of supporting structure in the construction and operation of karst highway tunnel from four aspects: static excavation, blasting construction, seismic response and vehicle load. The conclusions are as follows:
(1) The bench construction of Xiaobatian karst highway tunnel is simulated by ANSYS finite element software, and the stability of surrounding rock and the safety of lining structure are analyzed in combination with the stress of surrounding rock, plastic zone of surrounding rock, deformation of lining, stress of lining, safety factor of lining and cracking coefficient of lining proposed by Griffith criterion. All the above results meet the requirements of the code, indicating that the surrounding rock of Xiaobatian karst highway tunnel is stable and the supporting structure is safe during excavation.
(2) Based on the model of Xiaobatian tunnel and the engineering geological conditions, the influence of karst caves at different locations on the stability of surrounding rock and the safety of supporting structure is analyzed. From the plastic zone of surrounding rock, displacement of characteristic points, stress of lining and safety factor of lining, it is determined that the karst cave at the side of tunnel is the shadow of surrounding rock and lining supporting structure. The most unfavorable distribution.
(3) According to the most disadvantageous position that the lateral karst cave has the greatest influence on the surrounding rock and the lining supporting structure, the ratio of diameter to diameter and the ratio of spacing to spacing are introduced. The influence of the distance between the karst cave and the tunnel and the change of the size of the karst cave on the stability of the surrounding rock and the safety of the supporting structure of the tunnel are analyzed by means of numerical experiments. When the diameter ratio is less than 0.217, the influence of karst cave on tunnel tends to be zero, which can not be considered in tunnel design and construction. When the spacing ratio is greater than 1.419, the influence of karst cave on tunnel tends to be stable.
(4) By consulting relevant literatures, the blasting vibration velocity, the stress extremum of each particle and the blasting damage index BDI were taken as the criteria to judge whether the cave was safe during the blasting construction of Xiaobatian tunnel. The blasting construction of Xiaobatian tunnel was simulated by ANSYS finite element software, and the maximum safe vibration velocity was obtained by the damage and fracture criterion of surrounding rock. Degree of 13.74 cm/s, dynamic tensile strength of surrounding rock 2.13 Mpa, dynamic compressive strength of surrounding rock 23.25 Mpa, blasting damage index BDI "f 1.0" to evaluate the stability of karst cave in Xiaobatian tunnel during blasting construction, the calculation results meet the requirements of the code, indicating that the karst cave in Xiaobatian karst highway tunnel blasting construction will not be destabilized.
(5) Based on the dynamic calculation model and engineering geological conditions of Xiaobatian tunnel, the influence of blasting construction on the karst caves at different locations (the karst caves are located at the top, the bottom and the side of the tunnel) is analyzed from the angles of maximum vibration velocity, maximum tensile and compressive stress, and maximum blasting failure index. The most unfavorable distribution of holes.
(6) According to the karst cave located at the bottom of tunnel is the most disadvantageous position which is affected by blasting construction to karst cave, starting from the distance between karst cave and tunnel, the relationship between the distance between karst cave and tunnel and the maximum vibration velocity is v=88.187x-0.797, and the safe distance between tunnel and karst cave blasting construction is 1.15D.
(7) The EL-Centro wave after baseline correction and filtering is selected, and the horizontal acceleration load of EL-Centro wave is applied to the dynamic calculation model of Xiaobatian tunnel by ANSYS finite element software. The vibration velocity law of tunnel lining and karst cave characteristic points under seismic load is analyzed, and the maximum tensile and compressive stress and stress increment of lining and karst cave are used to judge the lining. The results show that the maximum tensile stress of the lining is 0.752 Mpa, the maximum compressive stress is 2.45 Mpa, the maximum tensile stress of the surrounding particles is 0.169 Mpa, and the maximum compressive stress is 2.126 Mpa. All the above results meet the requirements of the code, indicating that the Xiaobatian tunnel will not be damaged by tension and fracturing under earthquake.
(8) Finite element models of karst cave located at the top, side and bottom of tunnel are established respectively. EL-Centro wave horizontal acceleration load is applied to the model. Comparisons are made between the displacement, velocity, circumferential principal stress extremum and principal stress increment of tunnel lining and karst cave. The lateral part is the most unfavorable distribution area of the karst cave.
(9) The dynamic response of karst highway tunnel under vehicle load is simulated by using ANSYS finite element software with the vehicle load considered as the exciting force function in the dynamic calculation model of Xiaobatian tunnel. The lining of karst highway tunnel under vehicle load is judged by the maximum vibration velocity, stress extreme value and stress increment of lining and karst cave. The results show that the influence of vehicle load on tunnel and karst cave is very small, and the instability of tunnel structure and karst cave will not occur under vehicle load.
【学位授予单位】：兰州交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U455;U458

【参考文献】