【摘要】：在凍結(jié)法鑿井中,凍結(jié)管斷裂事故時(shí)常發(fā)生,帶來(lái)嚴(yán)重后果。據(jù)專家初步推測(cè),砂層凍結(jié)壁內(nèi)、外部的凍脹力是造成凍結(jié)管斷裂的主要因素之一。為此,本文采用解析分析、物理試驗(yàn)和數(shù)值計(jì)算相結(jié)合的方法,對(duì)飽和砂層雙圈管凍結(jié)過(guò)程中內(nèi)部?jī)雒浟Φ淖兓?guī)律展開(kāi)了研究。首先,根據(jù)厚壁圓筒理論,對(duì)雙圈管凍結(jié)模型進(jìn)行受力模型簡(jiǎn)化,首次提出采用厚壁圓筒拉梅解、位移連續(xù)、體積相容方法,對(duì)雙圈管平面應(yīng)變模型進(jìn)行理論解析,建立凍脹力與凍結(jié)壁厚度的函數(shù)關(guān)系,得出凍脹力隨凍結(jié)壁厚度呈先線性后加速的增長(zhǎng)趨勢(shì)。在理論解基礎(chǔ)上,進(jìn)行單因素分析,得出凍結(jié)壁彈性模量越大、凍結(jié)壁厚度越大、飽和介質(zhì)含水率越大,凍脹力越大。其次,通過(guò)數(shù)值模擬研究,采用優(yōu)化后的熱應(yīng)變系數(shù)計(jì)算方法,建立雙圈管凍結(jié)空間軸對(duì)稱模型,探究了典型參數(shù)下模型位移場(chǎng)、溫度場(chǎng)和凍脹應(yīng)力場(chǎng)的變化規(guī)律。得到凍結(jié)壁形成過(guò)程中,兩圈管之間土體將發(fā)生徑向、豎向位移,靠近內(nèi)外圈中點(diǎn)處,位移量最大,內(nèi)圈管和外圈管處位移值一致;另外,凍脹力改變模型內(nèi)部應(yīng)力分布,且豎向應(yīng)力增幅大于徑向應(yīng)力。針對(duì)各因素的單因素分析得出,介質(zhì)含水率越大,凍脹力越大,凍結(jié)管間距越大、排距越大,凍脹力越小。第三,自行設(shè)計(jì)模擬裝置,通過(guò)試驗(yàn)研究獲得了封閉環(huán)境下純水、飽和砂凍結(jié)過(guò)程中溫度場(chǎng)、凍脹應(yīng)力場(chǎng)的變化規(guī)律。在試驗(yàn)筒約束下,模型內(nèi)部產(chǎn)生較大凍脹力,凍脹力使得內(nèi)部徑向、豎向和切向應(yīng)力明顯增大,在試驗(yàn)研究范圍內(nèi),凍脹力隨凍結(jié)壁厚度呈線性增長(zhǎng)變化。雙圈管凍結(jié)條件下飽和砂層內(nèi)部產(chǎn)生凍脹力,凍結(jié)管處于拉、彎應(yīng)力狀態(tài)下,若飽水砂層處因初始缺陷、接頭等造成凍結(jié)管強(qiáng)度不足,極易造成斷管事故,故凍結(jié)設(shè)計(jì)中,在穿越富水地層處,凍結(jié)管應(yīng)采取錯(cuò)開(kāi)接頭、增加強(qiáng)度或異步凍結(jié)等措施,減小乃至避免凍脹力,從而有效避免斷管事故的發(fā)生。
[Abstract]:In freezing shaft sinking, the breakage of freezing pipe often occurs, which brings serious consequences. According to experts' preliminary theory, the frost heaving force is one of the main factors causing the fracture of frozen pipe. In this paper, analytical analysis, physical test and numerical calculation are used to study the variation of internal frost heave force during the freezing process of double-circle pipe in saturated sand layer. Firstly, according to the thick-walled cylinder theory, the mechanical model of the double-ring tube freezing model is simplified, and the theoretical analysis of the double-ring tube plane strain model is proposed by using the Lamy solution of the thick-walled cylinder for the first time, the displacement is continuous and the volume compatible method is used to analyze the plane strain model of the double-ring tube. The relationship between frost heaving force and freezing wall thickness is established. It is concluded that the frost heave force increases linearly and then accelerates with the frozen wall thickness. On the basis of theoretical analysis, it is concluded that the greater the elastic modulus of the frozen wall, the greater the thickness of the frozen wall, the greater the moisture content of saturated medium and the greater the frost heave force. Secondly, through the numerical simulation study and the optimized calculation method of thermal strain coefficient, the axisymmetric model of double loop tube freezing space is established, and the variation law of displacement field, temperature field and frost heave stress field of the model under typical parameters are explored. The results show that during the formation of freezing wall, the soil between the two loops will have radial and vertical displacement, close to the middle point of the inner and outer ring, the displacement of the inner ring and the outer ring will be the same, in addition, the frost heave force will change the stress distribution in the model. The increase of vertical stress is larger than that of radial stress. According to the single factor analysis of each factor, the larger the moisture content of the medium, the greater the frost heave force, the greater the distance between freezing tubes, the larger the row distance and the smaller the frost heave force. Thirdly, the simulation device is designed, and the variation of temperature field and frost heave stress field in the freezing process of pure water and saturated sand in closed environment are obtained by experiments. Under the constraint of the test tube, there is a large frost heave force inside the model, and the internal radial, vertical and tangential stresses are obviously increased by the frost heave force. In the range of experimental study, the frost heave force increases linearly with the thickness of the frozen wall. Under the condition of double circle tube freezing, the frost heaving force is produced in saturated sand layer. When the frozen tube is in tension and bending stress, if the initial defect and joint of saturated sand layer cause the freezing pipe strength to be insufficient, it is easy to cause pipe breakage accident, so in freezing design, In order to reduce or even avoid frost heave force, the freezing pipe should take staggered joint, increase strength or asynchronous freezing in order to avoid the accident of pipe breakage.
【學(xué)位授予單位】：中國(guó)礦業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TD265.3

【參考文獻(xiàn)】

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本文編號(hào)：2157314