小净距交叉隧道爆破振动控制技术研究

发布时间：2018-11-20 19:31

【摘要】：本论文以中川城际铁路与兰州北编组站联络线北环隧道上穿兰州枢纽工程红山顶隧道为依托工程，从理论分析、爆破振动监测和数值模拟等几个方面对小净距空间交叉隧道施工爆破技术及控制措施进行系统研究，为设计、施工决策提供基础资料和理论技术支持，以保证北环隧道的成功修建，并为其它类似地质条件下的隧道工程建设提供有益的参考。主要研究内容及其结论如下： (1)根据现场隧道爆破振动监测得到的振动速度和混凝土动应变数据，进行线性拟合得到了振动速度与动应变的关系，基于近接施工容许拉应力增量控制标准，确定本工程采用爆破振动安全振速控制标准为7.0cm/s。 (2)依据爆破安全规程及已有小净距隧道施工研究资料，通过萨道夫斯基公式确定了北环隧道重点监测范围为距交叉点±20m。基于安全考虑取三个方向的总合成速度作为爆破振动振速控制标准，新建北环隧道交叉断面±20m范围内爆破施工时既有隧道最大振速为5.89cm/s，小于拟定的爆破振动安全速度。 (3)通过大量文献及现场实测数据分析，爆破振动强度主要受地质条件、爆心距、装药量、爆破条件（爆破位置、临空面条件）等多个方面影响。在萨道夫斯基公式的基础上，并拟合得到了适用于北环隧道的爆破振动经验公式，将掏槽爆破作为爆破振动控制重点，重点监测。 (4)对爆破振动波型图进行频谱分析和主频分布分析，经过傅里叶变换，获得典型的北环隧道爆破振动信号频谱图，确定了振动波主频域的分布范围。基于爆破安全规程，将主振频率作为爆破振动控制标准的判据，需要严格控制爆破振动波频率远离结构自身频率，避免由于共振作用造成的损害。 (5)基于爆破振动强度的影响因素，对原有爆破方案在通过小净距影响区域时进行调整，通过修改钻孔设计，控制装药量，增加起爆次数，减小开挖进尺，，选择合理的雷管起爆时差等方法，将爆破振动影响降低到最低限度。 (6)通过ANSYS分析软件，建立小净距立体交叉隧道的三维模型。通过数值模拟计算，上台阶掏槽爆破时既有隧道的最大振速小于7cm/s的振速控制值。既有隧道交叉断面衬砌拉压应力和拉压应力增量也都满足规范要求，说明在爆破过程中，既有隧道衬砌结构安全可靠。 (7)采用ANSYS有限元软件模拟交叉段前后新建隧道台阶法施工时掏槽爆破对既有隧道的动力响应。通过振动速度、应力的大小来判断爆破过程中既有隧道衬砌结构安全性，既有隧道衬砌最大振动小于7cm/s的安全振速，衬砌最小抗压、抗拉安全系数和拉压应力增量也都满足安全性要求。
[Abstract]:Based on the project of Zhongchuan Intercity Railway and the North Ring Tunnel of Lanzhou North marshalling Station, this paper takes the Hongshan Tunnel, a project of Lanzhou hub, as the basis of theoretical analysis. Blasting vibration monitoring and numerical simulation are used to systematically study the blasting technology and control measures in the construction of small clear-spaced space crossing tunnel, which provides basic data and theoretical and technical support for design and construction decision. In order to ensure the successful construction of the North Ring Tunnel, and to provide a useful reference for other similar geological conditions of the tunnel construction. The main research contents and conclusions are as follows: (1) the relationship between vibration velocity and dynamic strain is obtained by linear fitting according to the vibration velocity and dynamic strain data obtained from field blasting vibration monitoring. Based on the control standard of allowable tensile stress increment in near-connection construction, it is determined that the safe vibration velocity control standard of blasting vibration is 7.0 cm / s. (2) on the basis of blasting safety regulations and the existing research data of small clear distance tunnel construction, the critical monitoring range of North Ring Tunnel is determined to be 卤20m from intersection point by Saadolski formula. Based on the safety considerations, the total synthetic velocity in three directions is taken as the control standard of blasting vibration velocity, and the maximum vibration velocity of the existing tunnel is 5.89 cm / s when blasting is constructed in the range of 卤20m cross section of the new North Ring Tunnel, and the maximum vibration velocity of the existing tunnel is 5.89 cm / s. Less than the proposed safety speed of blasting vibration. (3) through the analysis of a large number of documents and field measured data, the vibration intensity of blasting is mainly affected by geological conditions, the distance between the blasting centers, the charge quantity, the blasting conditions (the blasting position, the condition of the face near the air), and so on. On the basis of Sadolski's formula and fitting, the empirical formula of blasting vibration suitable for North Ring Tunnel is obtained. Cutting blasting is regarded as the key point of blasting vibration control and monitoring. (4) the spectrum analysis and main frequency distribution analysis of blasting vibration wave pattern are carried out. Through Fourier transform, the typical spectrum chart of blasting vibration signal of North Ring Tunnel is obtained, and the distribution range of main frequency domain of vibration wave is determined. Based on the blasting safety regulations, the main vibration frequency is regarded as the criterion of blasting vibration control standard. It is necessary to strictly control the frequency of blasting vibration wave to avoid the damage caused by resonance. (5) based on the influence factors of blasting vibration intensity, the original blasting scheme is adjusted when passing through the area affected by small net distance. By modifying the borehole design, the charge quantity is controlled, the number of detonation is increased, and the excavation advance is reduced. The blasting vibration effect is reduced to the minimum by selecting reasonable detonator time difference and other methods. (6) the three-dimensional model of cross tunnel with small net distance is established by ANSYS software. By numerical simulation, the maximum vibration velocity of existing tunnel is smaller than that of 7cm/s. Both the tensile and compressive stress and the increment of the tensile and compressive stress of the cross-section lining of the existing tunnel meet the requirements of the code, which shows that the lining structure of the existing tunnel is safe and reliable during blasting. (7) ANSYS finite element software is used to simulate the dynamic response of cutting blasting to the existing tunnel during the step construction of the new tunnel before and after the cross section. The safety of existing tunnel lining is judged by vibration speed and stress. The maximum vibration of existing tunnel lining is less than that of 7cm/s, and the minimum pressure of lining is obtained. The safety factor of tension and the increment of tension and compression stress also meet the safety requirements.
【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】：U455.6

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