摘要
富水隧道水岩作用的复杂性导致岩体内部孔隙结构的演化具有不稳定性,会诱发岩体的劣化、失稳等现象,这对地下渗流岩体稳定性的研究提出了更高的要求。为探究贵阳下麦西隧道灰岩在渗透水压作用下溶蚀孔隙结构的演化规律,对不同渗透水处理的灰岩试件进行了声发射、压汞、SEM及荧光光度试验,获得了灰岩溶蚀质量损失率、波形、频谱图、孔隙分布曲线及电镜扫描图像等。结果表明:灰岩质量损失率随渗透压增加呈缓慢增加-快速发展的发展趋势,渗透压分界点为6 MPa。随着渗透压增加,波形首波振幅逐渐衰减,波形曲线衰减较快且较早趋于稳定,波尾发育程度减缓。灰岩主频峰值逐渐衰减,由单峰向多峰演化,主频峰值与渗透压呈二次函数关系,且声波频率由(相对)高频段向低频段发展。溶蚀灰岩的大、中孔隙对渗透能力起到了决定性作用。随渗透压增加,灰岩累计进汞量呈指数函数增加,CaCO3和SiO2成分含量均呈指数函数变化。机械溶蚀较为敏感,化学溶蚀受溶蚀时间限制无法在短期内快速发展,机械溶蚀占据主导作用。建立的接触冲刷模型表明,渗透水的拖拽力取决于水流速度,而渗透压的提高则可增加单位体积的水压力梯度,进而提高水流速度。
In karst water-enriched tunnel, due to the complexity of water-rock coupling effect, the evolution of pore structure in rock mass is unstable and will induce the deterioration and instability of rock mass, which puts forward higher requirements for the research of the stability of underground permeability rock mass. Firstly, to investigate the effect of osmotic pressure on the karst pore structure, osmotic test, acoustic emission test, mercury injection test, SEM test and fluorescence photometric test were carried out on limestone from Maixi tunnel, Guiyang, treated with different osmotic pressures. Then, the mass loss rates, P-wave patterns and frequency spectrum, pore distribution curves and scanning electron microscope images were obtained. Results show that the mass loss rates of limestone show the tendency of "slow increase-rapid development" with the increase of osmotic pressure, and the demarcation points of the two phases is 6 MPa. With the increase of osmotic pressure, the amplitude of head wave gradually decays, and the waveform curve first decays quickly and then tends to be stable early, and the development degree of wave tail gradually slows down. Also, it is found the peak of dominant frequency gradually decays and evolves from single peak to multiple peak and has excellent quadratic function with osmotic pressure, and that the wave frequency develops from(relatively) high frequency to low frequency. Besides, the macropores and mesopores formed by dissolution play a decisive role in the permeability of limestone. With the increase of osmotic pressure, the accumulation of mercury increases exponentially. Meanwhile, the mineral contents including CaCO3 and SiO2 change exponentially. Compared with chemical dissolution, mechanical dissolution is more sensitive to time and dominates the formation of pores. In additional, the established water-rock contacting dissolution model indicates that the drag force of osmotic water depends on its flow velocity, while the increase of osmotic pressure can enlarge the osmotic pressure gradient, thus increasing the flow velocity.
作者
宋战平
程昀
杨腾添
霍润科
王军保
刘新荣
SONG Zhan-ping;CHENG Yun;YANG Teng-tian;HUO Run-ke;WANG Jun-bao;LIU Xin-rong(School of Civil Engineering,Xi'an University of Architecture and Technology,Xi'an,Shaanxi 710055,China;Shaanxi Key Laboratory of Geotechnical and Underground Space Engineering,Xi’an University of Architecture and Technology,Xi’an,Shaanxi 710055,China;China Railway Bridge Engineering Bureau Group Co.,Ltd.,Tianjin 300300,China;School of Civil Engineering,Chongqing University,Chongqing 400044,China)
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2019年第12期4607-4619,4643,共14页
Rock and Soil Mechanics
基金
国家自然科学基金（No.51578447）
住房和城乡建设部科学技术计划项目（No.2017-K4-032）~~
关键词
灰岩
渗透压
水岩作用
孔隙
溶蚀作用
limestone
osmotic pressure
water-rock interaction
pore
dissolution action
