本文關鍵詞： 采煤 突水潰砂 假粘聚力 啟動含水量 質量流量 孔隙水壓力 土壓力　出處：《中國礦業(yè)大學》2015年碩士論文　論文類型：學位論文

【摘要】：本文以西部高強度開采條件下小紀汗煤礦覆巖(土)的工程地質條件、水文地質條件為背景,以顆粒流動理論、水砂運移理論為指導,通過試驗研究開采引起的松散砂潰砂流動運移規(guī)律及機理。在分析總結陜北煤礦區(qū)潰砂特性、研究小紀汗礦區(qū)覆巖(土)的工程地質、水文地質特征基礎上,采用室內模型試驗探究突水潰砂過程中因素及機理。取得的主要研究成果如下:(1)結合煤礦潰砂案例,概括了陜北礦區(qū)潰砂的基本特性,即:水量大、含砂比高、波及地表等。詳細研究了小紀汗井田的工程地質條件和水文地質條件,從水砂物源、潰砂通道和水動力條件分析了影響潰砂的因素,得出:潰砂的砂源主要來自風積砂和第四系薩拉烏蘇組的沖積砂;水源主要來自薩拉烏蘇組孔隙含水層;潰砂通道主要是基巖風化帶薄的區(qū)域的天然潰砂通道和開采引起的覆巖破壞帶。(2)對潰砂流動過程的分析表明,干砂具備較好的流動性,飽和水砂也具備較好流動性形成水砂混合流;而當砂土中具有較小的含水量時,由于毛細作用,具有一定的假粘聚力,呈現(xiàn)出一定的穩(wěn)定性。當含水量從0過渡到飽和時,存在一個含水量,在大于該含水量后,砂土的假粘聚力變?yōu)?,水砂混合物容易形成流動。本文將假粘聚力為0時的含水量定義為潰砂啟動含水量:即水砂混合物在自重應力下由穩(wěn)態(tài)轉變?yōu)榱鲬B(tài)的含水量。模型試驗結果驗證了潰砂啟動含水量的存在。(3)對砂土的直接剪切試驗表明,內摩擦角隨著含水量的增加先減小后增加,在10%的含水量時存在最小值;假粘聚力隨著含水量增加呈二次曲線先增加后減小。最大假粘聚力時,含水量隨著粒徑增大呈指數(shù)遞減;同一含水量下的假粘聚力隨著粒徑有減小的趨勢。(4)研究了潰砂的質量流量變化特征。水砂混合物質量流量先增大后降低后分階段周期性降低。砂厚/水頭高度的值越小,所形成的漏斗開口越大,越近似于錐形。淹沒于水面以下,漏斗表面砂顆粒是在重力和動水沖力共同作用沿著坡面進行坡面流。當裂隙開啟潰砂發(fā)生,裂隙周圍底板孔壓會瞬時響應,都會呈現(xiàn)不同程度的孔壓降低和震蕩變化。土壓力增大比例約在15%-20%。底板上的土壓力存在明顯的土拱效應。(5)結合潰砂剖面特征二維潰砂剖面概化了潰砂概念模型,發(fā)現(xiàn)裂隙開啟瞬時整個潰砂剖面豎直方向首先流動響應,從潰砂剖面結合孔壓變化,提出通道開啟后的基巖面孔壓分布范圍,并給出了分布計算式。參考地下水井流影響半徑的分析思路,提出瞬時孔壓影響半徑這一概念,并得出了半經驗公式�？讐阂鸬乃ζ露缺人蛔兓鸬乃ζ露软憫�,這一改變將促進潰砂的形成。
[Abstract]:In this paper, the engineering geological conditions and hydrogeological conditions of overburden rock (soil) in Xiao-Jihan coal mine under the condition of high-strength mining in the west of China are taken as the background, and the theory of particle flow and the theory of water-sand migration are taken as the guidance. On the basis of analyzing and summarizing the characteristics of sand collapse in North Shaanxi coal mine and studying the engineering geology and hydrogeological characteristics of overburden rock (soil) in Xiaojihan mining area, this paper studies the law and mechanism of loose sand flow and migration caused by mining. The main research results are as follows: (1) combined with the case of coal mine, the basic characteristics of sand bursting in North Shaanxi mining area are summarized, that is, large amount of water. The engineering geological conditions and hydrogeological conditions of Xiaojihan well are studied in detail, and the factors influencing the sand bursting are analyzed from the sources of water sand, sand crashing passage and hydrodynamic conditions. The results show that the sand source of burst sand mainly comes from the aeolian sand and the alluvial sand of the Quaternary Salawusu formation; The source of water mainly comes from the pore aquifer of the Sarawusu formation; The analysis of the flow process of overburden sand flow in the area with thin weathering zone of bedrock and rock overburden caused by mining shows that dry sand has good fluidity. Saturated water and sand also have good fluidity to form mixed flow of water and sand; However, when the sand has a small water content, it has a certain pseudocohesive force due to the capillary effect, showing a certain stability. When the water content from 0 to saturation, there is a water content. When the water content is greater than the water content, the pseudo-cohesive force of sand becomes 0. The water and sand mixture is easy to flow. In this paper, the water content of the pseudo-cohesive force of 0:00 is defined as the initial water content of the burst sand. That is, the water content of the mixture of water and sand changed from steady state to flowing state under the self-gravity stress. The model test results verified the existence of water content at the start of sand burst. 3) the direct shear test of sand shows that. The internal friction angle decreases first and then increases with the increase of water content, and there is a minimum value when the water content is 10%. The pseudo-cohesive force increases first and then decreases with the increase of water content. When the maximum pseudo-cohesive force increases, the water content decreases exponentially with the increase of particle size. Under the same water content, the pseudo-cohesion tends to decrease with the particle size. The characteristics of mass flow change of crushed sand are studied. The mass flow rate of water-sand mixture first increases and then decreases periodically, and the value of sand thickness / head height is smaller. The larger the opening of the funnel is, the closer it is to the cone. The sand particles on the surface of the funnel flow along the slope under the interaction of gravity and hydrodynamic forces. The pore pressure of the bottom plate around the crack will be instantaneous response. The proportion of the increase of earth pressure is about 15 to 20. The earth pressure on the bottom plate has obvious soil arch effect. Combined with the characteristics of sand bursting profile, the conceptual model of sand bursting is generalized in two-dimensional sand bursting section. It is found that the vertical direction of the whole sand burst section is the first flow response, and the distribution range of the bedrock face pressure after the opening of the channel is put forward from the break sand profile combined with the pore pressure change. The concept of instantaneous pore pressure influence radius is put forward with reference to the analysis of the influence radius of water well flow under the ground. The semi-empirical formula is obtained. The response of hydraulic slope caused by pore pressure is earlier than that of hydraulic gradient caused by water level change, which will promote the formation of sand rout.
【學位授予單位】：中國礦業(yè)大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TD745

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