【作者】 刘永胜；

【导师】 王梦恕； 傅洪贤；

【作者基本信息】 北京交通大学 ， 桥梁与隧道工程， 2010， 博士

【摘要】 海底隧道钻爆开挖条件下的围岩稳定性研究是一个新兴而复杂的课题,其兼有爆破过程的复杂性与海底岩体含水和多裂隙的复杂性。海底含水裂隙岩体对爆破作用的响应过程和结果构成了海底隧道钻爆开挖过程中围岩稳定性研究的主体。本文在研究含水裂隙岩体爆破机理的基础上,通过现场实测和数值模拟手段,对爆破作用下海底隧道围岩稳定性进行了详细研究。论文取得的主要成果如下:1)基于断裂力学和爆炸力学理论,研究了含水裂隙岩体的断裂破坏机理和破坏过程。分析了爆破作用下含水裂隙岩体不同阶段裂隙的断裂扩展机理,提出了含水裂隙岩体断裂准则。研究了爆炸应力波作用下裂隙岩体的破坏类型;2)从应力场和振动场两方面分析了条形药包爆破作用机理和爆破特征,研究了裂隙岩体含水和含气时应力波衰减系数的区别;3)通过现场实测得到了Ⅱ级围岩和Ⅴ级围岩钻爆开挖振动场规律,证实了隧道钻爆开挖振动场具有与单个条形药包爆破振动场相似的规律。基于实测数据,通过数值模拟得到了隧道拱顶以及掌子面前后岩石质点振动速度衰减规律,分析了每循环不同爆破进尺条件下隧道围岩中的振动场特征,回归了V级围岩中爆破开挖隧道拱顶岩层交界面附近剪应力的计算公式:4)通过现场实测研究了Ⅱ级围岩和Ⅴ级围岩中钻爆开挖松动圈的形成过程。分析了Ⅱ级围岩大断面隧道中爆破作用和应力重分布对隧道总松动圈大小的影响比例。得到了适合厦门海底隧道地质条件下的岩石爆破振动损伤临界速度,并得出Ⅱ级围岩和Ⅴ级围岩中每循环合适的开挖长度;5)提出了爆破作用影响隧道围岩稳定性的关键因素。研究了爆炸应力波作用下裂隙岩体断裂破坏范围并提出了新的破坏范围计算公式;分析了爆破作用影响隧道围岩渗透性的区域分布特点,并提出了爆炸应力波作用后岩体中的渗透系数计算公式;研究了岩层分界面与隧道拱顶的最小安全距离;探讨了爆破作用诱发涌水的类别及涌水机理,推导了动静应力场叠加作用下隧道涌水时临界水压表达式。综合分析得出了Ⅱ级围岩和Ⅴ级围岩中海底隧道覆盖岩层临界厚度的控制因素;6)基于对现有成果的总结与研究,建议在海底隧道钻爆掘进过程中,采用改进的中导洞超前全断面扩挖技术。更多还原

【Abstract】 The study on surrounding rock-mass stability of subsea tunnel during excavation with drilling and blasting method was a new and complicated subject, owing to the complex blasting process and sophisticated water-bearing and multi-crack subsea rock-mass. The influencing process of water-bearing fractured rock-mass on blasting, as well as its result, plays a major role in the surrounding rock-mass stability analysis of subsea tunnel during excavation with drill and blasting method. Based on the blasting mechanism of water-bearing fractured rock-mass, and with in-site tests and numerical studies, this thesis systematically analyzed the surrounding rock-mass stability of subsea tunnel during blasting excavation. The main achievements are as follows:Firstly, based on fracture mechanics and explosion mechanics theory, this thesis studied the fracture failure mechanism of water-bearing fractured rock-mass. And after analyzing the propagation mechanism of crack at different stage of water-bearing fractured rock-mass, the fracture principles of water-bearing fractured rock-mass were proposed. Failure types of fractured rock mass due to blasting stress wave were also studied.Secondly, the explosive mechanism and the feature of linear charge were analyzed from the perspective of stress field and vibration field. The distinctions of the attenuation coefficient of stress wave between water-bearing fractured rock-mass and air-bearing fractured rock-mass were identified.Thirdly, through in-site test, the vibration laws of surrounding rock-mass in grade II and V in the process of drilling and blasting excavation were gained, which proved that the tunnel’s vibration field during drill and blast excavation was similar to that of the single linear charge. Based on the tested date and simulation, the thesis gained the attenuation law of vibration in the zone of tunnel vault and pre-and-post of tunnel face, identified the characteristic of vibration field under different blasting footage condition, and regressed the calculation formula of shear stress in interface of rock stratum.Fourthly, with in-site test, the size of excavation damage zone of the surrounding rock-mass in grade II and V during blasting excavation was gained, and the affecting rate of the total excavation destroy zone of the tunnel causing by blasting and the stress redistribution were analyzed, through which we got the critical velocity of blasting vibration damage suitable for Xiamen Subsea Tunnel geological condition, as well as the suitable blasting length for every loop. Fifthly, the thesis put forward the key affecting factors of blasting on surrounding rock-mass stability. The range of fracture failure zones under the influence of blasting stress wave was identified and the calculation formula of the failure zone was also proposed. The influence of blasting on the attribution of the permeability area in the surrounding mass-rock was analyzed, and the calculation formula of permeability coefficient caused by stress wave was presented. The minimal safe distance between interface of rock stratum and tunnel vault was analyzed. The classification of water inflow induced by blasting and the water inflowing mechanism were studied, and with the effect of overlapping dynamic and static stress field, the calculation formula of the critical inner water pressure in water inflow was presented. At last, the controlling factors of covering-rock’s critical thickness for surrounding rock-mass grade II and V in subsea tunnel were proposed.Sixthly, through studying the achievements made before, the thesis suggests that it is better to apply the improved technique of full-face expansion leading with under-pilot hole in subsea tunnel blasting excavation.更多还原