攀枝花机场三叠系泥岩工程特性及软化机理研究

发布时间：2019-03-16 07:07

【摘要】：研究区位于攀枝花机场12#滑坡东侧,场区基岩主要为三叠系宝顶组泥岩段,以炭质泥岩为主,夹砂岩、粉砂质泥岩。12#滑坡及下方易家坪老滑坡下伏基岩上,绝大部分分布有泥岩,填筑料因取自宝顶组泥岩段,含大量的泥岩碎块碎屑。显然,攀枝花机场10.3填筑体失稳及老滑坡复活都与泥岩的软化有关。因此,本文针对该地区泥岩遇水软化的特性开展一系列试验研究,并得出以下几点认识:(1)泥岩初始成分及结构是泥岩(块)、泥岩结构面遇水软化的基础。研究区泥岩主要由粘土矿物、原生矿物、简单盐类、碳质组成。其中,粘土矿物含量占50~95%,原生矿物占4%~35%;简单盐类中大多数为可溶盐。碳质含量占1%~10%,与粘土矿物呈互染状,将削弱粘土矿物颗粒之间的联结。从微观结构上,粘土矿物呈隐晶-微晶质集合体、平行堆叠结构,粘土矿物与原生矿物颗粒之间为固体盐类胶结。以上初始成分结构,决定了研究区泥岩的天然强度不高(单轴抗压强度≈10MPa),水稳性差、软化性强。(2)采用纯水浸泡试验表明:(1)研究区泥岩(块)含水率、孔隙率在饱水过程中均呈现持续上升、单轴抗压强度及抗剪强度则呈持续衰减趋势;饱水30天后,泥岩含水率、孔隙率分别增长122.77%、142.72%;单轴抗压强度下降81%,c、f值分别减小67.86%和53.12%;(2)泥岩结构面物理力学性质的变化趋势大体上同泥岩(块)的变化趋势,但它与水的作用更剧烈,软化过程更快,其抗剪强度指标饱水10天后就开始趋于稳定。饱水30天后,含水率、孔隙率分别增长166.67%、195.97%,c、f值分别减小63.27%和41.67%。(3)泥岩的浸润具有明显的各项异性特征。无应力状态下,浸润方向平行层理面时含水率、孔隙率及浸润深度上升速率明显比垂直层理面组快。在不同剪应力水平下,沿剪切(潜在破坏)面方向的浸润深度、上下试块的含水率、孔隙率均随剪应力水平增加而增大;剪切面平行层理时的浸润深度、含水率、孔隙率的增长要大于垂直层面剪切的情况,且在低应力水平两者的差异较大,在较高应力水平两者差异较小。(4)地下水与应力作用是导致泥岩软化的主要外部因素。采用研究区地下水作浸泡液,泥岩的化学成分的溶解与析出受到一定程度的抑制,泥岩力学性状的软化程度不及纯水浸泡液的情况。此外,在一定的应力作用下,不仅会直接导致泥岩矿物颗粒之间的结构联结弱化,而且所产生的微裂纹,有利于地下水的浸入,从而加剧泥岩的软化过程。(5)研究区泥岩软化主要存在四种物理化学作用:一是以固体可溶盐溶解析出为特征的化学溶蚀作用;二是伴随泥岩溶蚀、孔隙增多增大过程的楔劈作用;三是泥岩中白云母、长石的水解作用;四是水的润滑作用。其中,化学溶蚀作用是主要的,且随饱水时间的增加而减弱,楔劈作用主要发生在饱水的中后期(即化学溶蚀进行到一定程度);水解作用总体比较微弱,润滑作用主要存在于有贯通裂隙的情况(如泥岩结构面的情况)。(6)将泥岩(块)及结构面的软化过程大体上都分为三个过程。泥岩(块):软化开始阶段(饱水0~10天)→软化持续阶段(饱水10~30天)→软化稳定阶段(饱水30~60天);泥岩结构面:软化开始阶段(饱水0~5天)→软化持续阶段(饱水5~30天)→软化稳定阶段(饱水30~60天)。
[Abstract]:The research area is located on the east side of the 12 # landslide of Panzhihua Airport. The bedrock of the site is mainly of the mudstone section of the Triassic Baoding Formation, mainly of the carbonaceous mudstone, with sandstone and silty mudstone. The underlying bedrock of the old landslide of the 10 # landslide and the lower Yijiaping landslide is mainly distributed with mudstone. The filling material is taken from the mudstone section of the Baoding Formation and contains a large amount of mudstone and fragment debris. It is clear that the failure of the filling body and the revival of the old landslide at the Panzhihua Airport are related to the softening of the mudstone. Therefore, a series of experiments have been carried out on the characteristics of the water softening of mudstone in the area, and the following understandings are drawn: (1) The initial component and structure of the mudstone are mudstone (block), and the surface of the mudstone is on the basis of water softening. The mudstone of the study area is mainly composed of clay minerals, organic minerals, simple salts and carbonaceous materials. In which the content of clay mineral accounts for 50-95%, the mineral content is 4-35%, and most of the simple salts are soluble salts. The carbonaceous content is from 1% to 10%, and the clay mineral is intermixed, and the connection between the clay mineral particles is reduced. From the microstructure, the clay mineral is a cryptocrystalline-microcrystalline aggregate, a parallel stack structure, and a solid salt is cemented between the clay mineral and the mineral particle. The above initial component structure determines that the natural strength of the mudstone in the study area is not high (the uniaxial compressive strength is less than 10MPa), the water stability is poor, and the softening property is strong. (2) The pure water soaking test shows that: (1) The water content and porosity of the mudstone (block) in the study area are continuously increasing in the water-saturated process, and the uniaxial compressive strength and the anti-shear strength show a continuous attenuation trend; after 30 days of saturation, the water content and the porosity of the mudstone are increased by 122.77%, respectively. 142.72%; single-axis compressive strength decreased by 81%, c, f value decreased by 67.86% and 53.12%, respectively; (2) the change tendency of the physical and mechanical properties of the mudstone structural plane was generally the same as that of the mudstone (block), but it was more severe than water and the softening process was faster. The anti-shear strength index is stable after 10 days of water saturation. After 30 days of water saturation, the water content and porosity increased by 166.67%, 195.97%, c, and f respectively by 63.27% and 41.67%, respectively. (3) The infiltration of mudstone has distinct characteristics of the opposite sex. In the non-stress state, the rate of water content, porosity and infiltration depth of the parallel bedding surface in the infiltration direction is higher than that of the vertical bedding plane. At different shear stress levels, the depth of infiltration along the direction of shear (potential destruction), the water content and porosity of the upper and lower test blocks increase with the increase of the shear stress level, the infiltration depth, the water content and the porosity in the parallel bedding of the shear plane are greater than that of the vertical plane shear. And the difference between the two stress levels is relatively large, and the difference between the two stress levels is small. (4) The effect of groundwater and stress is the main external factor leading to the softening of mudstone. Using the groundwater in the study area as the soak solution, the dissolution and precipitation of the chemical components of the mudstone are restrained to a certain extent, and the softening degree of the mechanical properties of the mudstone is less than that of the pure water soaking solution. In addition, under a certain stress, not only can the structural connection between the mudstone mineral particles be weakened directly, but also the micro-cracks are generated, which is beneficial to the immersion of the underground water, thereby increasing the softening process of the mudstone. (5) There are four physical and chemical functions of the softening of the mudstone in the study area: the first is the chemical dissolution which is characterized by the dissolution of the solid soluble salt; the second is the wedge action of the process of increasing the dissolution of the mudstone and the increase of the porosity; the third is the hydrolysis of the muscovite and the feldspar in the mudstone; And fourth, the lubricating effect of water. in which, the chemical corrosion action is main, and decreases with the increase of the water-saturated time, the wedge action mainly occurs in the middle and late period of water-saturated water (that is, the chemical dissolution is carried out to a certain degree), the hydrolysis effect is relatively weak, The lubrication effect mainly exists in the case of the through-crack (such as the case of the mudstone structure surface). (6) The softening process of the mudstone (block) and the structural surface is generally divided into three processes. Mudstone (block): softening start phase (water-saturated for 0-10 days), softening and steady phase (water-saturated for 10-30 days), softening and stabilizing phase (water-saturated for 30-60 days); mudstone structure surface: softening-start phase (water-saturated for 0-5 days) and softening-lasting stage (water-saturated for 5-30 days) and softening and stabilizing stage (water-saturated for 30-60 days).
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU45;V351.1

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