利用ANSYS WORKBENCH模拟火山岩浆活动热扩散过程
发布时间：2018-12-18 16:03
【摘要】：火山喷发必然伴随着高温岩浆侵入体把热量从岩石圈深部携带到地壳浅层的过程,因而火山区往往也是地热资源富集区。火山岩浆侵入体热扩散过程的数值模拟不仅是火山区构造热演化研究的重要手段,而且也是火山区地热资源评估的重要方法。本文利用在工程热物理领域应用甚广、但在地热地球物理领域鲜有报道的有限元软件ANSYS WORKBENCH对火山活动岩浆冷却过程及其对围岩的热扰动过程进行了数值模拟。首先本文建立一系列简单的柱状模型,模拟了不同规模、不同顶板埋深的侵入体的热扩散过程,引入冷却指数α=(T_(侵入)-T)/(T_(侵入)-T_(稳态))×100%及干扰温差ΔT=T-T稳态分别来定量分析岩浆侵入体冷却过程及围岩受侵入体热扩散扰动程度。结果表明,半径为0.5km的柱状侵入体的冷却时间约为50ka左右,对围岩热扰动持续时间不到0.5Ma,最大横向热扰动范围约为3km。而半径1km的柱状侵入体的冷却时间约为200ka左右,对围岩温度场影响可持续1.4Ma,热扰动范围可至7km。顶板埋深越大,侵入体对围岩热扰动的持续时间越短。在上述模拟实验的基础上,本文结合最新的相关研究成果,模拟计算了上地壳岩浆房和上中地壳岩浆房两种情景下长白山天池火山千年大喷发对于温度场的可能影响。结果表明,无论其岩浆房位于上地壳或中地壳上部,千年大喷发对于围岩的热扰动目前还局限于500m左右的范围内,这可能是区内尚无大规模地热显示的原因。
[Abstract]:Volcanic eruptions must be accompanied by high temperature magmatic intrusions to carry heat from the deep lithosphere to the shallow crust. Therefore, thermal mountain areas are often rich in geothermal resources. Numerical simulation of thermal diffusion process of volcanic magma intrusive body is not only an important means to study the thermal evolution of thermal structure in the volcanic mountain area, but also an important method to evaluate geothermal resources in the volcanic area. In this paper the cooling process of volcanic magma and the thermal disturbance of surrounding rock are numerically simulated by using finite element software ANSYS WORKBENCH which is widely used in engineering thermal physics but rarely reported in geothermal geophysics. First of all, a series of simple cylindrical models are established to simulate the thermal diffusion process of intrusions with different sizes and different roof depths. The cooling index 伪 = (T _ (intrusive) -T) / (T _ (intrusive) -T _ (steady) 脳 100% and disturbance temperature difference 螖 T=T-T steady state are introduced to quantitatively analyze the cooling process of magmatic intrusions and the disturbance degree of surrounding rock by thermal diffusion of intrusive body. The results show that the cooling time of cylindrical intrusions with radius of 0.5km is about 50ka, the thermal disturbance duration of surrounding rock is less than 0.5 Ma, and the maximum transverse thermal disturbance range is about 3 km. The cooling time of the columnar intrusions with radius 1km is about 200ka, and the influence on the temperature field of surrounding rock is 1.4 Ma, and the thermal disturbance range is up to 7 km. The deeper the roof is, the shorter the duration of thermal disturbance of surrounding rock is. On the basis of the above simulation experiments, the possible effects of the millennium eruption of Tianchi volcano in Changbai Mountain on the temperature field under the two scenarios of the upper crust magma chamber and the upper middle crust magma chamber are simulated and calculated in combination with the latest relevant research results. The results show that, no matter the magma chamber is located in the upper crust or the upper middle crust, the thermal disturbance caused by the millennium eruption to the surrounding rock is still limited to about 500 m, which may be the reason that there is no large-scale geothermal display in the area.
【作者单位】： 西安交通大学全球环境变化研究院地热与环境研究实验室;美国密歇根大学地球与环境科学系;
【基金】：国家自然科学基金项目(41374089)资助
【分类号】：P588.14
本文编号：2386086
[Abstract]:Volcanic eruptions must be accompanied by high temperature magmatic intrusions to carry heat from the deep lithosphere to the shallow crust. Therefore, thermal mountain areas are often rich in geothermal resources. Numerical simulation of thermal diffusion process of volcanic magma intrusive body is not only an important means to study the thermal evolution of thermal structure in the volcanic mountain area, but also an important method to evaluate geothermal resources in the volcanic area. In this paper the cooling process of volcanic magma and the thermal disturbance of surrounding rock are numerically simulated by using finite element software ANSYS WORKBENCH which is widely used in engineering thermal physics but rarely reported in geothermal geophysics. First of all, a series of simple cylindrical models are established to simulate the thermal diffusion process of intrusions with different sizes and different roof depths. The cooling index 伪 = (T _ (intrusive) -T) / (T _ (intrusive) -T _ (steady) 脳 100% and disturbance temperature difference 螖 T=T-T steady state are introduced to quantitatively analyze the cooling process of magmatic intrusions and the disturbance degree of surrounding rock by thermal diffusion of intrusive body. The results show that the cooling time of cylindrical intrusions with radius of 0.5km is about 50ka, the thermal disturbance duration of surrounding rock is less than 0.5 Ma, and the maximum transverse thermal disturbance range is about 3 km. The cooling time of the columnar intrusions with radius 1km is about 200ka, and the influence on the temperature field of surrounding rock is 1.4 Ma, and the thermal disturbance range is up to 7 km. The deeper the roof is, the shorter the duration of thermal disturbance of surrounding rock is. On the basis of the above simulation experiments, the possible effects of the millennium eruption of Tianchi volcano in Changbai Mountain on the temperature field under the two scenarios of the upper crust magma chamber and the upper middle crust magma chamber are simulated and calculated in combination with the latest relevant research results. The results show that, no matter the magma chamber is located in the upper crust or the upper middle crust, the thermal disturbance caused by the millennium eruption to the surrounding rock is still limited to about 500 m, which may be the reason that there is no large-scale geothermal display in the area.
【作者单位】： 西安交通大学全球环境变化研究院地热与环境研究实验室;美国密歇根大学地球与环境科学系;
【基金】：国家自然科学基金项目(41374089)资助
【分类号】：P588.14
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