Subjects: Mechanics >> Applied Mechanics submitted time 2023-03-20 Cooperative journals: 《应用力学学报》
Abstract： With the increasing mining depth of mineral resources , the problem of thermal hazand in hightemperature underground space is increasingly serious.The research on new heat insulation technology andheat insulation technology has become an important research direction to control the heat transfer of sur-rounding rock. Based on the effect of air layers on heat insulation in building envelope and tunnel , themethod of applying enclosed air layer to control the heat dissipation of surounding rock is proposed. The temperature field distribution of surrounding rock with air layer is solved by ANSYS Fluent software. Basedon the similarity theory , an experimental platform for the temperature field of roadway surrounding rockwith air layer was designed. The numerical results were verified by the experimental results , which showedthat the two results were in good agreement. So,the simulation results of ANSYS Fluent are reliable. Baseon experimental results and the simulation results the variation law of the temperature field in surroundingrock in unsteady heat transfer is analyzed. It is found that the temperature field at the top, middle and bot-tom of the surrounding rock is different because of the existence of natural convection in the air layer , andthe dimensionless radius of the temperature regulating ring is less than that of the normal roadway. The in-fluence of the thickness of air interlayer on the heat release of surrounding rock is studied by example cal-culation.It is found that the thickness of air layer has little effect on heat loss of surrounding rock. Whenthe thickness of small air layer increases from 2 cm to 20 cm,the heat loss per unit length of surroundingrock only decreases by 5% . The thermal conductivity of surrounding rock has a significant influence on thethermal insulation rate of air interlayer ,the decay rate of the heat dissipation of the thermal conductivity of0.59 W/(m 稫)is faster than that of 6.18 W/(m 稫).The enclosed air layer insulation structure issuitable for temporary insulation of new tunneling roadway or permanent insulation of fixed or semi-fixedoperation site with high thermal conductivity of surrounding rock.
Subjects: Geosciences >> Other Disciplines of Geosciences submitted time 2019-09-10 Cooperative journals: 《干旱区研究》
Abstract：标准化降水蒸散指数(SPEI)通过标准化潜在蒸散与降水的差值，表征一个地区干湿状况偏离常年的程度，是分析干旱演变趋势的新的理想指标，目前已经广泛应用于干旱评估、水资源管理等领域。利用SPEI和1961—2015年新疆天山山区8个代表站点的月降水量及月平均气温资料，对天山山区55 a以来气温和降水的变化特征、不同时间尺度的干旱变化特征、草地生长季干旱特征及变化趋势进行了分析，结果表明：近55 a，天山山区气温呈现显著的上升趋势；降水量总体呈略微上升的趋势，但年际变化较大，变化趋势不显著；天山山区月、季、半年尺度以及年尺度的干旱事件分别为42个、25个、16个和7个；天山山区草地生长季发生轻度、中度和重度干旱的频率分别为37.5%、7.1%和1.8%；近55 a，天山山区草地生长季降水量有所增加，但由于气温升高带来的蒸散作用加强，气候仍呈变干的趋势。近55 a来，天山山区草地生长季气候存在变干的倾向，且年际间的干旱程度变化剧烈，对草地的年际间生长状况差异存在较大的影响。
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