【作者】 宋小林；

【导师】 张继春；

【作者基本信息】 西南交通大学 ， 岩土工程， 2008， 博士

【摘要】 近年来,我国国民经济得到了快速的发展,公路、铁路、机场及水利水电工程等基础设施建设遇到了前所未有的发展机遇,这些工程往往穿越各种山区地形,常会遇到各种复杂的地貌形态和工程地质环境,因此边坡稳定性问题更加突出。工程岩质边坡的稳定主要取决于岩体内各种地质结构的性质、空间展布以及开挖爆破形成边坡过程中爆破作用对地质结构性态的影响程度。正确分析爆破动力作用对岩质边坡稳定的影响直接关系到工程边坡的修建和使用安全,尤其是在边坡内含有顺倾软弱夹层时,穿过软弱层的深孔爆破对边坡稳定的影响更为显著。因此,如何正确分析爆破作用下软弱顺倾岩质边坡的稳定已成为亟解决的一个重要问题,一直是岩石力学界和爆破工程界关注的热点问题。当爆破炮孔穿过顺倾岩质边坡的软弱层时,爆轰气体和爆炸冲击波引起紧邻炮孔的软弱介质移动压密而在一定范围内形成爆破空腔,空腔区内软弱层被推移冲刷走,使该范围内粘聚力完全丧失和内摩擦角降低为零,坡体的抗滑力消失;在压密区内软弱层内的粘聚力和内摩擦角虽然均有所增加,但是层间的粘聚力急剧减小,甚至完全丧失,对边坡的稳定十分不利;与此同时,在爆腔形成过程中,伴随着爆轰气体的楔入,使上覆岩层(潜在滑体)受到爆轰气体的压力作用而产生向上的挠曲变形,导致数十倍炮孔直径范围内的岩体与软弱夹层分离即岩体发生层裂破坏,使该范围内的粘聚力为零,内摩擦角减小,而使该范围内的坡体抗滑力极大降低,从而导致边坡在爆破过程中形成局部或整体滑动。因此,要正确解决爆破作用下含顺倾软弱夹层的边坡岩体稳定性分析问题,必须首先明确爆破过程中边坡岩体的受力状态,建立相应的爆破数学力学模型,才能给出合理的边坡动力稳定性计算方法。为此,本文应用爆炸力学理论,从爆轰气体沿堵塞方向和软弱夹层方向等熵绝热膨胀的角度,分析爆轰气体楔入软弱夹层后边坡岩体的受力状态,建立深孔爆破过程中边坡岩体的准静态力学模型,导出了爆炸作用在软弱夹层内形成爆腔后的准静态压力和软弱层临界层裂长度计算公式。通过分析爆轰气体楔入层面内对边坡岩体产生的抬动作用,导出了边坡潜在滑体的动力稳定系数同装药参数、岩体力学参数和边坡几何尺寸的定量关系,提出了一种分析顺倾岩质边坡的爆破动力稳定性的新途径。针对顺倾边坡爆破时爆轰气体冲刷、压密软弱夹层而形成爆腔从而影响边坡稳定的问题,应用爆轰流体动力学和气液两相流理论,分析了在钻孔爆破过程中软弱夹层在爆轰气体作用下的压密和推移机理,建立了爆破过程中软弱夹层的运动力学模型,导出了在爆轰气体作用下软弱夹层的运动速度、最终爆腔半径和扩腔时间同装药参数和软弱夹层力学参数的定量关系。利用高速摄影技术进行了爆轰气体作用下软弱夹层充填物运动速度的测定,分析了软弱充填物运动速度的变化规律,同时还得到了软弱夹层中的爆腔形状和尺寸。利用声波探测技术进行了试验模型的声波速度探测,得到了模型在爆破前后的声波速度,分析了不同测点声波速度变化的规律和原因,提出了确定软弱夹层中形成的爆腔半径和压密区半径等变形特性的方法,为顺倾岩质边坡的爆破动力稳定分析提供可靠的基础数据。利用有限元LS-DYNA3D程序,模拟并研究了其它工况条件下软弱夹层的变形随软弱层厚度及倾角、炮孔直径、装药量和药柱长度与直径之比的变化规律,扩充和完善了模型试验和运动力学模型。最后,经过实例分析表明深孔爆破过程中边坡岩体的准静态力学模型具有很好的准确性,它从爆破原理上综合考虑了爆轰气体的扩散和楔入作用等因素,较以往边坡爆破动力稳定性分析更进一步。更多还原

【Abstract】 With the rapid development of our national economy, the infrastructure industry, such as highway, railway, airport, and water conservancy and hydropower engineering have gotten into an unprecedented high-speed development opportunity. These projects always meet all kinds of complicated environment and geology. So the slope stability problem becomes more outstanding and stern. The stability of rock slope mainly depends on the properties and the distribution in space of geological structure in rock mass, especially on the influence of blasting on the properties of geological structure during the excavation of rock cutting slope. It is the precondition of correctly analyzing the stability of slope caused by blasting dynamic to direct the related slope design and safe use. The blasting in layered rock mass with a weak intercalation has remarkable influences on the slope stability. So, how to analyze the stability of layered rock slope with weak intercalation becomes an important problem to be resolved with urgency.When the charge hole drill through weak intercalation of layered rock slope, with the erosion, impulse, and compaction of weak intercalation caused by explosion gases and blasting shock waves, the blasting cavity comes into being. In the area of blasting cavity the cohesive force and the internal friction angle have decreased to zero, and meanwhile, the cohesive force in the compact zone of weak intercalation decreases sharply, even loses completely, which is very harmful to the slope stability. On formation process of blasting cavity, with the explosion gases wedging into the interface between weak intercalation and rock mass, the rock formation on the top of the weak intercalation is bended upwards caused by explosion gases, which leads to the rock separates from the weak intercalation, that is to say, stratification cracking occurs. In the stratification cracking range, the cohesive force decreases to zero and the internal friction angle also decreases, which leads to the self-stability of rock mass reducing and the sliding resistance of slope decreasing. It is every easy to cause layered landslide, and even to lead the formed slope to landslide or collapse. So, it is essential for the analyses of the stability of layered rock slope with weak intercalation that the stress states of the slope rock during the blasting must be made certain and the corresponding mathematical mechanical model of blasting is to be established, based on which the reasonable calculation method of the dynamic stability of slope can be provided.Aimed at the stability analysis of layered rock slope effected by the erosion, impulse, and compaction of the weak intercalation caused by blasting, and applied on the theory that blasting gas is isoentropy adiabatic expansion in the lamination cracks and charge hole, the quasi-static mechanical model for the lamination of weak intercalation in layered rock slope was established during the deep-hole blasting. The explicit expressions of the quasi-static pressure in the blasting cavum and the critical lamination length of the weak intercalation were deduced. Through the study on the raise effect of the rock mass caused by the blasting gas wedging into the weak intercalation, the quantitative relationship between the stability factor of the latency slip and the parameters of charge, the mechanics parameters of the rock and the geometry size of the slope was obtained. A new approach for analyzing the dynamic stability of layered slope was opened.Applied on the theory of detonation fluid dynamics and two-phase flow theory of gas liquid, the mechanism of the compaction of the weak intercalation caused by explosive gases during the blasting was studied, and the motion mechanical model of weak intercalation was established. The quantitative relationship between the velocity of the weak intercalation, the final radius and the expansion time of blasting cavity and the parameters of charge, the mechanics parameters of the weak intercalation were obtained.The velocity of the weak intercalation caused by explosive gases was measured with the aid of a high-speed digital camera, and its variations was analysed. The shape and the size of blasting cavity in weak intercalation were gained, besides.The acoustic velocities of the models before and after blasting were measured with the acoustic detection technique. The variations and the cause of acoustic velocities in different measuring points were analysed. And based on the variations in different measuring points before and after blasting, a new approach to determining the radius of blasting cavity and the compact zone was come up.The characters of weak intercalation in other work conditions have been investigated through LS-DYNA3D program, and the thickness and the obliquity of weak intercalation, and the mass, the diameter and the ratio of length to diameter of the charge effect on the blasting cavities radius have been analyzed.At last, the blasting dynamic stability of the two typical layered rock slopes was analyzed using the quasi-static mechanical model presented and the result indicated that it was agreed with the engineering practice.更多还原