基于透明土的采掘溃砂流动形态试验研究

发布时间：2018-07-20 12:44

【摘要】：突水溃砂作为一种地质灾害,严重威胁着诸如采矿、隧道开挖等地下工程的施工及生产安全。为了研究在溃砂过程中砂体的流动形态变化规律,本文利用透明土试验技术原理,采用熔融石英砂和矿物油配制出性质与天然砂体近似的透明土试样。根据采掘溃砂的地质特征,对地质条件进行了综合简化,并依此设计制作了透明土溃砂试验系统,获取了不同试验条件下溃砂过程中的砂流内部的激光散斑图像。采用数字图像处理技术中的图像相关法原理,利用自行编写的软件实现了对砂体内部运动情况的分析。据此,对溃砂发生过程、阶段特点以及溃砂流动形态进行了研究,并分析了砂颗粒粒径、溃砂口宽度、水头高度等三个因素对溃砂流动的影响。同时,结合不同地质条件,对溃砂砂体积总量进行了计算。本文获得的主要成果有:(1)根据试验观测了溃砂发生的基本过程,在溃砂开始后,砂体最初仅在溃砂孔口位置附近区域发生流动,但发展速度迅速。很快就形成了类似柱状的流动区域即柱状流动区域,并在柱状流动区域顶部产生凹陷,开始形成漏斗。受漏斗影响而发生运动的范围即漏斗状区域。伴随着溃砂的发展,柱状流动区域高度不断下降,漏斗状区域不断扩大。柱状流动区域消失后,漏斗状区域在维持一段时间的扩展后,达到极限而停止时,砂体随之趋于稳定,溃砂结束。依据溃砂发展过程中速度和流量随时间的变化规律,溃砂发生过程可以划分成四个阶段:启动阶段、稳定阶段、失稳阶段、结束阶段。(2)试验表明,溃砂砂体内部存在着两种不同类型的的流动形式,即柱状流动区域的流动形式和漏斗状区域的流动形式。柱状流动区域的流动形式的特点表现为主要发生垂向的运动,速度方向垂直向下,其速度场分布近似相切于一点不断扩展的系列椭圆,越往溃砂孔靠近速度越大。漏斗状区域的流动形式呈现层状的速度分布特点,表层移动速度大,往砂体内部逐步减小直至停止,速度方向沿漏斗坡面向下,影响范围分布在漏斗两侧砂体坡面表层。对柱状流动区域的流动形式进行了描述,通过分析拟合获得了柱状区域的流动速度表达式。试验发现溃砂流动形态存在两种模式,即:“坡面均匀下降溃砂模式”和“坡面非均匀下降溃砂模式”。(3)试验表明,溃砂流速、流量等会受到颗粒粒径大小、溃砂口裂隙宽度和水头高度等因素的影响。随着颗粒粒径、溃砂口裂隙宽度和水头高度的增大,流速和流量会变大,启动速度加快。其中颗粒粒径、溃砂口裂隙宽度的增大,会引起柱状流动区域的变宽。三者均对溃砂流动模式有较大影响,一般颗粒越细、溃砂口裂隙宽度越宽、水头高度越高的情况下,越容易发生坡面非均匀下降溃砂模式。(4)分析了影响溃砂体积的因素,研究了不同条件下溃砂体积计算的方法。溃砂砂体积总量与砂层上方是否存在覆盖层有很大关系。计算可知无覆盖层条件下溃砂砂体积总量大于有覆盖层的条件下发生坡面非均匀下降溃砂模式的溃砂砂体积总量,而坡面均匀下降溃砂模式的溃砂砂体积量在三种情况中最小。
[Abstract]:As a geological hazard, water inrush and sand burst is a serious threat to the construction and production safety of underground engineering such as mining, tunnel excavation and so on. In order to study the flow pattern change law of sand body during the process of sand break, this paper uses the principle of transparent soil test technology to make up the approximate transparency of the nature and the natural sand body by using the fused silica sand and mineral oil. According to the geological characteristics of the excavation of sand, the geological conditions were simplified, and a transparent sand test system was designed and made. The laser speckle image inside the sand flow in the process of sand break under different test conditions was obtained. The principle of image correlation method in digital image processing technology was used to make use of the software of self writing. According to the analysis of the internal movement of sand body, the process of sand break, the stage characteristics and the flow pattern of sand break are studied, and the effects of three factors such as sand particle size, the width of the sand break and the height of the water head on the flow of sand break are analyzed. The main achievements obtained in this paper are as follows: (1) the basic process of sand break was observed by experiments. After the sand break began, the sand body began to flow only in the vicinity of the hole of the sand break, but the speed of development was rapid. The column like flow area was formed quickly, and a depression was produced at the top of the column like flow area. As the funnel is affected by the funnel, the scope of the movement is the funnel area. With the development of sand break, the height of the columnar flow area continues to decline and the funnel like area expands continuously. After the column flow area is disappearing, the sand body tends to stabilize and sands when the funnel like region extends for a period of time and reaches the limit. The process of sand break can be divided into four stages: starting stage, stable stage, instability stage and end stage. (2) tests show that there are two different types of flow forms inside the sand broken sand body, that is, the flow form and funnel of the column flow area. The flow form of a columnar region. The flow form of the column shaped flow area is characterized by the main vertical movement. The velocity direction is vertical downward. The velocity distribution is similar to a series of ellipses that continue to expand at a point. The closer to the velocity of the sand hole, the flow form in the funnel shaped region presents a stratiform velocity distribution characteristic. The moving velocity of the layer is large and gradually decreases to the inside of the sand body to stop, the velocity direction is down along the funnel slope, and the influence range is distributed on the surface surface of the sand body on both sides of the funnel. The flow form of the column like flow area is described. The flow velocity expression of the columnar region is obtained by the analysis and fitting. The test finds that the flow pattern of the sand break exists. The two models, namely, "a uniform decline in the sand break mode of the slope" and "the non uniform declines in the sand break mode". (3) the experiment shows that the flow rate and flow rate of the sand break are affected by the particle size, the crack width and the head height of the sand break. With the particle size, the width of the crack and the height of the head, the flow rate and the flow rate The size of particle size and the widening of the crack width of the sand break will cause the widening of the column like flow area. The three all have great influence on the flow pattern of sand break. The finer the general particles are, the wider the crack width is, the higher the height of the head is, the more easily the model of the sloping surface decreases. (4) analysis of the model. The factors affecting the volume of sand break are studied. The calculation method of sand crushing volume under different conditions is studied. The volume of sand crushing sand is closely related to the existence of the covering layer above the sand layer. The calculation shows that the volume of sand sand under the condition of uncovered layer is larger than that of the overburden layer. The total volume of sand and sand in uniform slope descending mode is the smallest in three cases.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P694

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