A great deal of data obtained from production practice indicates that in medium-hard seams and softer seams the resistance of rear leg is smaller than that of front leg in a sublevel caving powered support. When caving the top-coal, the resistances of both front leg and rear leg decrease, but the resistance of front leg decreases more than that of rear leg. In some cases, the resistance of rear leg even rapidly lowers to zero. This will seriously bring bad influence to making full use of the load-carrying capacity of the support, and damage the relation between support and surrounding rocks. So that to damage the control of the surrounding rocks of the face. The theory analysis points out that because the top-coal closed the gob is very fragmentized, lowering of the stiffness brings lowering of the load-carrying capacity, so the support’s acting point of the load moves frontward and thus the resistance of the rear leg is smaller than that of the front leg. Because of the top-coal’s further fracturing and moving the fact becomes more serious when top-coal is caving. The extreme case is that the resistance of the rear leg decreases to zero. Based on the theory analysis, the paper presented some measures to improve the load-bearing condition of the support. For example, changing the structure of the powered support and not caving too much top-coal, etc.

高温岩体地热开发及核废料的地下处置等需要对高温高压下花岗岩体的力学行为进行深入细致研究。采用自主研制的“20 MN伺服控制高温高压岩体三轴试验机”，投入大量人力、财力和物力，历时0.5 a，系统深入地研究φ 200 mm×400 mm的大尺寸花岗岩试样在高温三轴应力下的热变形和破坏特征及其热学和力学参数随温度的变化特征。研究结果表明：(1) 在三维静水应力下，花岗岩的热变形可分为低温缓慢变形段、中高温快速变形段及高温平缓变形段等3个阶段，自由状态测定的热膨胀系数会过分夸大，或失真地估计岩石的热膨胀或热力作用，在应力状态下测定的热膨胀系数更能反映实际岩体状态；(2) 在高温三轴应力条件下，花岗岩体受压表现出与常温下不一致的变形特征，即先是体积膨胀，当差应力超过一定值后则体积收缩；(3) 花岗岩体在高温下的破坏形式是典型的剪切破坏，与常温下的破坏形式一致，但在高温和高围压条件下出现明显的延性转化；(4) 在有围压条件下，花岗岩体的弹性模量随温度升高先是缓慢减小，然后快速减小，超过400 ℃后基本保持不变，与小试件的情况相似。

Utilizing information from plate tectonics characteristics, volcanic activities, and geothermal anomaly, this paper identifies areas where hot dry rock (HDR) may exist as potential geothermal resource in China. Further investigations are also carried out in the paper based on results from regional tectonics, volcanic geology and lithology, as well as data from geothermal displays, geochemistry, geophysics, and shallow borehole temperature measurements. The study reveals several promising areas of HDR geothermal resource in China, including Tengchong of Yunnan province, Qiongbei of Hainan province, Changbaishan of Jilin province, Wudalianchi of Heilongjiang province, and the Southern Tibet area. A 3D static heat conduction model was developed to study the underground temperature gradient characteristics of the Rehai geothermal field in Tengchong and the Yangbajing geothermal field in Tibet. The model adopted is a geological block 10 km deep from the ground surface and 50 km wide in each of the horizontal directions (2500 km2 area). The numerical simulation results in evaluations on the quantities of the HDR geothermal resource in Rehai and Yangbajing geothermal fields. The paper shows that there is abundant HDR geothermal resource with large exploitation value in China. If developed with a power capacity of 1!108 kW, the Rehai and Yangbajing fields along would be able to generate electricity for 1560 years.

介绍了美国洛斯阿拉莫斯国家实验室提出的高温岩体地热开发的概念模型，及在Fenton Hill进行的高温岩体地热开发试验的历程以及取得的研究成果。简述了日本、英国及法国等国家高温岩体地热开发方面取得的进展。分析评述了我国高温岩体地热资源的分布与资源量，初步提出了在我国进行高温岩体地热资源开发的设想。

研究了基于三维稳态热传导理论并忽略对流换热及地质构造等次要因素影响的地温场与地温梯度场的反演方法。该方法可以在大尺度上数值模拟岩体中地温的空间分布状况，并预测高温岩体地热资源量。以云南腾冲热海热田为例，模拟和分析了热田地下10 km以浅，水平展布50 km见方（2500 km2）范围地温场与地温梯度场的特点及其形成原因，并对热田高温岩体地热资源量进行了预测评价。文章提出的高温岩体地热资源的模拟与预测方法具有重要的理论价值，研究结果可为热海热田地热资源的开发利用提供重要参考。