本文選題：煤巖 + 蠕變��； 參考：《西安科技大學》2017年碩士論文

【摘要】：目前,我國煤炭生產(chǎn)的安全形勢仍然十分嚴峻,煤礦生產(chǎn)事故時有發(fā)生。地下采煤時,隨著開采時間的增加,煤柱在頂板壓力的作用下會發(fā)生蠕變現(xiàn)象,進而會使上層頂板失去支撐而坍塌破壞,出現(xiàn)煤礦事故。另一方面,煤巖體的導水性強,且遇水后力學性質(zhì)發(fā)生顯著變化,水是影響巖石蠕變性質(zhì)的一個重要因素。因此,對于地下采煤工程來說,研究不同浸潤條件下煤巖蠕變力學特性顯得尤為重要。論文針對礦區(qū)日益增長的工程需要,以試驗研究為基礎,借助DNS200型電子萬能試驗機、SAEU2S聲發(fā)射系統(tǒng)以及Vic-3D應變測量系統(tǒng),系統(tǒng)地研究煤巖在不同浸潤時間下的蠕變力學特性,為礦區(qū)采煤工程建設提供一定的理論基礎。從現(xiàn)場取回煤巖巖塊,加工成?50mm?100mm的國際標準試件,將試件分為4組,分別在水中浸潤0h、48h、96h、144h,并對4組試件分別進行單軸壓縮蠕變試驗,試驗過程中觀察并記錄煤巖蠕變破壞過程及破壞方式,探討煤巖蠕變峰值應力、軸向應變隨浸潤時間的變化規(guī)律,分析煤巖蠕變斷裂破壞的影響因素。結(jié)果表明:煤巖的蠕變破壞一般呈現(xiàn)為劈裂破壞;隨著浸潤時間的增加,煤巖的蠕變峰值應力逐漸降低,軸向應變呈現(xiàn)增大的趨勢。對經(jīng)歷不同浸潤時間(0h、48h、96h、144h)后的煤巖試件進行單軸壓縮蠕變聲發(fā)射特性試驗。研究煤巖蠕變試驗過程與聲發(fā)射參數(shù)之間的對應關(guān)系,分析浸潤時間對聲發(fā)射參數(shù)(振鈴計數(shù)、能量、幅度)的影響規(guī)律。研究表明:通過分析聲發(fā)射參數(shù)的變化可以很好的描述煤巖試件在蠕變過程中的各個階段的力學特征。借助Vic-3D應變測量系統(tǒng)為輔助工具,對煤巖單軸壓縮試驗進行監(jiān)測,通過散斑的移動得到二維應變,進而得到煤巖表面的應變云圖。結(jié)果表明:隨著浸潤時間的增加,煤巖試件的峰值應力與彈性模量逐漸降低,而峰值應變逐漸增大;在煤巖單軸壓縮破壞過程中,煤巖試件表面的應變演化云圖可以很好的與其破壞過程相對應,試件最終破壞是按照產(chǎn)生裂縫的區(qū)域開始斷裂。因此認為軸向與橫向應變的變化趨勢可以直觀再現(xiàn)煤巖的細觀力學特征,預測其最終破壞形態(tài)。
[Abstract]:At present, China's coal production safety situation is still very serious, coal production accidents occur from time to time.In underground coal mining, with the increase of mining time, the coal pillar will creep under the action of roof pressure, which will make the upper roof lose its support and collapse and destroy, resulting in coal mine accident.On the other hand, the water conductivity of coal and rock mass is strong, and the mechanical properties of coal and rock mass change obviously after water treatment. Water is an important factor affecting the creep property of rock.Therefore, for underground coal mining, it is very important to study the creep mechanical properties of coal and rock under different wetting conditions.Aiming at the increasing engineering demand in mining area, based on the experimental research, the creep mechanical properties of coal and rock under different soaking times are systematically studied by means of DNS200 electronic universal testing machine SAEU2S acoustic emission system and Vic-3D strain measurement system.It provides a certain theoretical basis for coal mining engineering construction in mining area.The coal and rock blocks were collected from the site and processed into international standard specimens of 50 mm to 100 mm. The specimens were divided into 4 groups, which were wetted in water for 0 h or 48 h or 96 h or 144 h, respectively, and four groups of specimens were subjected to uniaxial compression creep tests.The creep failure process and failure mode of coal and rock were observed and recorded during the test. The variation of creep peak stress and axial strain with soaking time were discussed and the influencing factors of creep fracture of coal and rock were analyzed.The results show that the creep failure of coal and rock is generally split failure and the creep peak stress of coal and rock decreases gradually and the axial strain increases with the increase of soaking time.The acoustic emission characteristics of uniaxial compression creep of coal and rock specimens after different wetting times were tested at 48h ~ 96h ~ 144h.The relationship between the creep test process of coal and rock and the acoustic emission parameters is studied, and the influence of soaking time on the acoustic emission parameters (ring count, energy, amplitude) is analyzed.The results show that the change of acoustic emission parameters can well describe the mechanical characteristics of coal and rock specimens in each stage of creep process.With the aid of Vic-3D strain measurement system, the uniaxial compression test of coal and rock was monitored, and the strain cloud map of coal and rock surface was obtained through the movement of speckle.The results show that with the increase of soaking time, the peak stress and elastic modulus of coal and rock specimens decrease gradually, while the peak strain increases gradually, and in the process of uniaxial compression of coal and rock,The strain evolution cloud map on the surface of coal and rock specimen can well correspond to the failure process, and the ultimate failure of the specimen is to start the fracture according to the area where the fracture occurred.It is concluded that the variation trend of axial and transverse strain can visualize the meso-mechanical characteristics of coal and rock and predict its ultimate failure form.
【學位授予單位】：西安科技大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TD315

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