發(fā)布時(shí)間：2018-06-06 04:42

  本文選題：覆蓋型巖溶塌陷 + 塌陷機(jī)理　； 參考：《合肥工業(yè)大學(xué)》2017年碩士論文

【摘要】：工程實(shí)踐表明,野外覆蓋型巖溶塌陷地質(zhì)條件復(fù)雜,對(duì)地下水運(yùn)移能力起重要作用的巖溶通道主要特征參數(shù)變化較大,溶洞開口大小也很難確定。由于現(xiàn)場(chǎng)試驗(yàn)存在著各方面限制,直接開展典型的標(biāo)準(zhǔn)系列試驗(yàn)以查清隱伏的巖溶通道特征和對(duì)應(yīng)的塌陷狀況難以實(shí)現(xiàn)。因此,在對(duì)安徽省沿江地區(qū)覆蓋型巖溶塌陷發(fā)育現(xiàn)場(chǎng)調(diào)查的基礎(chǔ)上,構(gòu)造蓋層-溶洞塌陷系統(tǒng)模型,開展模型試驗(yàn)?zāi)M研究,歸納總結(jié)了區(qū)內(nèi)巖溶塌陷的形成機(jī)理,進(jìn)而采用三維數(shù)值模擬的方法,對(duì)水位下降致塌進(jìn)行了數(shù)值模擬研究。本文安徽省沿江地區(qū)巖溶塌陷情況為研究背景,采用模型試驗(yàn)和數(shù)值模擬方法對(duì)巖溶塌陷臨界水位降幅進(jìn)行研究,以期為工程實(shí)踐提供理論依據(jù)。主要得出了以下成果:(1)地下水位波動(dòng)致塌,特別是水位下降致塌為主要致塌模式。人為開采地下水過(guò)程和礦山排水初期礦井突水引起的水位快速下降極易導(dǎo)致巖溶塌陷的發(fā)生,其致塌機(jī)理以潛蝕式塌陷為主,伴隨真空負(fù)壓效應(yīng)。(2)提出水位下降過(guò)程中塌陷發(fā)生的臨界水位降幅公式,利用正交試驗(yàn)原則設(shè)計(jì)四組覆蓋型巖溶塌陷模型試驗(yàn),對(duì)不同溶洞開口大小,覆蓋層厚度和土體密實(shí)程度進(jìn)行塌陷過(guò)程模擬。運(yùn)用臨界水位降幅實(shí)測(cè)數(shù)據(jù)對(duì)公式進(jìn)行評(píng)價(jià),驗(yàn)證結(jié)果表明所提出的計(jì)算臨界水位降幅的方法是可行的。(3)覆蓋型巖溶塌的臨界水位降幅與巖土體蓋層的厚度、強(qiáng)度指標(biāo)、巖溶的溶洞開口(土洞規(guī)模)半徑、溶洞內(nèi)氣壓大小、地下水位變化幅度和地下水流速等因素有關(guān),其中溶洞開口大小是影響塌陷發(fā)生的關(guān)鍵因素。(4)在物理模型試驗(yàn)的基礎(chǔ)上,采用數(shù)值模擬的方法進(jìn)行對(duì)比。對(duì)每組模型試驗(yàn)塌陷的過(guò)程進(jìn)行數(shù)值模擬計(jì)算,數(shù)值模擬得到的結(jié)果與實(shí)際符合較好。(5)銅陵朝山地區(qū)巖溶塌陷數(shù)值模擬計(jì)算結(jié)果表明:在一定的溶洞開口大小范圍內(nèi),隨著溶洞直徑增大,臨界水位降幅迅速減少;溶洞直徑超出一定范圍后,臨界水位降幅降低速度減慢,此時(shí)需考慮其他巖溶塌陷影響因素對(duì)臨界水位降幅的作用。
[Abstract]:The engineering practice shows that the geological conditions of overlying karst collapse are complex, the main characteristic parameters of karst channel which play an important role in groundwater migration capacity vary greatly, and the opening size of karst cave is difficult to determine. Due to the limitation of various aspects in the field tests, it is difficult to carry out the typical standard series tests directly in order to find out the characteristics of the concealed karst channels and the corresponding collapse conditions. Therefore, based on the field investigation of the overlying karst collapse in the area along the Yangtze River in Anhui Province, the model of caprock caverns collapse system is constructed, and the model test simulation is carried out, and the formation mechanism of karst collapse in this area is summarized. Furthermore, the three-dimensional numerical simulation method is used to simulate the collapse of water level. In this paper, the karst collapse situation along the Yangtze River in Anhui Province is studied by using model test and numerical simulation method to study the decrease of critical water level of karst collapse, in order to provide theoretical basis for engineering practice. The main results are as follows: 1) collapse caused by fluctuation of groundwater level, especially when the water level falls down as the main collapse mode. The process of artificial exploitation of groundwater and the rapid decrease of water level caused by mine water inrush in the early stage of mine drainage can easily lead to the occurrence of karst collapse, and the mechanism of collapse is mainly subsurface collapse. Following the vacuum negative pressure effect, the formula of critical water level decline occurred in the process of water level decline is put forward. Four groups of overlying karst collapse model tests are designed by using the principle of orthogonal test, and the opening sizes of different caverns are obtained. The collapse process is simulated by the thickness of overburden and the compactness of soil. The formula is evaluated by using the measured data of critical water level drop. The results show that the proposed method for calculating critical water level drop is feasible. The critical water level decrease of cover karst collapse and the thickness and strength index of rock and soil caprock are proved to be feasible. The karst cavern opening (soil hole size) radius, the pressure inside the karst cave, the variation of groundwater level and the groundwater velocity are related to each other, among which the cavern opening size is the key factor affecting the collapse, which is based on the physical model test. The method of numerical simulation is used to compare. The numerical simulation of the collapse process of each group of model tests is carried out. The results obtained by numerical simulation are in good agreement with the actual results. The results of numerical simulation of karst collapse in Chaoshan area of Tongling show that: in a certain range of cave openings, the numerical simulation results show that, With the increase of cave diameter, the decrease of critical water level decreases rapidly, and when the diameter of cavern exceeds a certain range, the decreasing speed of critical water level decreases. At this time, the effect of other factors of karst collapse on critical water level decline should be considered.
【學(xué)位授予單位】：合肥工業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：P642.25

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