泥石流冲击作用对拦砂坝基底扬压力的影响

发布时间：2018-01-25 11:56

本文关键词： 泥石流冲击力拦砂坝扬压力　出处：《西南科技大学》2017年硕士论文　论文类型：学位论文

【摘要】：泥石流拦砂坝基底扬压力作为一种重要荷载,对拦砂坝的稳定性有重要影响。在泥石流堆积土体的渗透特性研究基础上,结合拦砂坝的实际运行特点,将泥石流对拦砂坝的冲击作用与坝底扬压力相结合,开展了一系列模拟试验,并得到了一定研究成果:(1)通过渗透试验得出显著影响泥石流堆积土渗透性的细颗粒上限粒径为0.1mm,并且当土体中细颗粒含量达到20%后,渗透性降至10-5cm/s量级,属于弱透水级别。另外,击实试验表明,宽级配砾石土的最优细颗粒含量在15.68%~16.92%时,土体干密度趋于最大,孔隙度最小。(2)流体性质对泥石流的冲击作用有较大影响,当泥石流容重为2.0 g/cm3时,流体的流动性和整体性综合最优,在本次试验的各种工况下,该容重泥石流冲击力均为最大。泥石流的冲击力随体积的增大而增大,并且呈现出一定的线性关系。泥石流冲击力总体上随沟道坡度减小而减小,而且坡度对容重较大泥石流冲击特性的影响更大,即流体的流动性越差,受沟道坡度影响越明显。(3)泥石流冲击拦砂坝之后,由于坝前水头升高,拦砂坝基底扬压力几乎在同时产生突变,并在瞬间达到峰值,峰值数据和冲击前相比,平均增大3.02倍。冲击结束后,泥石流淤积于坝前,坝底渗流通道被堵塞,扬压力逐渐归零。(4)拦砂坝坝底沟床物质均匀、平缓,在坝底横向方面,扬压力的数值大小、变化幅度、变化趋势均保持一致。在坝底纵向方面,扬压力峰值数据和增量均表现为从坝前到坝后逐渐减小,并具有很好的线性关系,越靠近迎水面的扬压力增量更大,影响效果更显著。(5)拦砂坝受泥石流冲击之后,基底扬压力的演化规律主要为:随泥石流冲击作用而增大,随泥石流淤积而减小并最终归零。
[Abstract]:As an important load, the uplift pressure of the foundation of debris flow dam has an important effect on the stability of the dam. Based on the study of the seepage characteristics of debris flow accumulation soil, the actual operation characteristics of the dam are combined. A series of simulation tests were carried out by combining the impact of debris flow on the bar dam with the uplift pressure at the bottom of the dam. Through the permeation test, the upper limit particle size of the debris flow accumulation soil is 0.1 mm, and when the content of fine particles in the soil reaches 20%. The permeability decreases to 10-5 cm / s, which belongs to the weak permeability level. In addition, the compaction test shows that the optimum fine particle content of the wide-grained gravel soil is 15.68 ~ 16.92%. The dry density of the soil tends to be the largest and the porosity is the smallest. The fluid properties have a great influence on the impact of debris flow, when the bulk density of debris flow is 2.0 g / cm ~ 3. The fluidity and integrity of the fluid are optimal. Under various conditions of this experiment, the bulk density debris flow impact force is the largest, and the impact force of debris flow increases with the increase of volume. And there is a certain linear relationship. The impact force of debris flow decreases with the decrease of channel slope, and the impact of slope on the bulk density of debris flow is greater, that is, the fluidity of fluid is worse. The more obviously influenced by channel slope, the more obvious impact of debris flow on sand bar, because of the increase of water head in front of the dam, the uplift pressure of the basement of the dam almost simultaneously changes, and reaches the peak in an instant. The peak value data is 3.02 times larger than that before impact. After the impact, debris flow deposits in front of the dam, the seepage passage at the bottom of the dam is blocked, and the uplift pressure gradually returns to zero. 4) the material of the bottom ditch bed of the bar dam is uniform. In the horizontal aspect of the dam bottom, the value of the uplift pressure is the same, the range of variation and the change trend are the same. In the longitudinal aspect of the dam bottom, the peak data and the increment of the uplift pressure are gradually decreasing from the front of the dam to the back of the dam. And has a good linear relationship, the closer to the surface of the uplift pressure increment is greater, the effect is more significant. 5) sand bar after the impact of debris flow. The evolution law of basement uplift pressure is as follows: increase with debris flow impact, decrease with debris flow deposition and finally return to zero.
【学位授予单位】：西南科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P642.23

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