风载作用下震裂山体崩塌机制及稳定性评价方法

Collapse Mechanism and Stability Evaluation of Shattered Slope under Wind Loading

为了揭示风载作用下震裂山体的崩塌机制,建立其稳定性评价系统,在岩体震裂特征现场调查和河谷风现场测量的基础上,以茂县石大关乡崩塌为例,开展了不同条件下的大型风洞试验研究.研究结果表明:石大关乡崩塌为震裂山体在风载助推作用下发生溃崩的典型实例,此类灾害因震裂山体独特的结构特征,使得结构面对失稳模式的控制作用不再明显,加之河谷风受地形影响,分布规律复杂多变,具备与通常重力环境下斜坡失稳机制迥异的特征,整体以溃崩式失稳,表现为迅速解体—溃散—垮塌;岩体震裂损伤是崩塌产生的基础,渐近性风化是主要致灾因素,河谷强风的助推是崩塌发生的诱因之一;岩块的失稳风速与风的入射夹角、岩块的高宽比和后缘缝隙的宽度成反比.

To reveal collapse mechanisms of shattered slope under wind loading, the slope stability assessment system was built. Based on the field survey of shattered slopes and valley wind measurement, the large-scale wind tunnel tests in various conditions were conducted by using Shidaguan collapse as an example. The results indicate that Shidaguan collapse is a typical case of shattered slope collapsing in a sudden burst under wind loading. This mode of collapse are hardly controlled by structural plane because of the unique slope structure. Meanwhile, since the distribution of river valley wind is affected by the topographical elements, it becomes complicated and varied. Thus the sudden collapse mode undergoes fast breakdown-crumbling-collapse as a whole, quite distinct from slope failure mechanisms under general gravity force. The loosing and cracking of the rock masses is fundamental to the collapse, while the gradual weathering is the main factor. Besides, the strong river- valley winds aggravate the collapse. Furthermore, the wind speed leading to rock masse instability is in inverse proportion to wind incident angle, as well as the height-width ratio of mass, and the width of the trailing edge crack.