20MN伺服控制高温高压岩体三轴试验机的研制

RESEARCH AND DEVELOPMENT OF 20 MN SERVO-CONTROLLED ROCK TRIAXIAL TESTING SYSTEM WITH HIGH TEMPERATURE AND HIGH PRESSURE

详细介绍自行研制的20 MN伺服控制高温高压岩体三轴试验机,该试验机主要由主机加载系统、高温压力室与温控系统、辅机装料系统以及测试系统4个部分组成。最大轴压和侧压均为10 000 kN,试样尺寸为φ200 mm×400 mm,试样最高加热稳定温度为600℃。介绍试验机研制的关键技术难点和解决方案,与普通用于地球物理研究的高温高压试验机相比,具有如下显著特点:(1)试样大,是普通的高温高压试验机试样体积的64倍,可以更好地反映岩体的特性;(2)实现伺服控制加载,可以方便地研究岩体在各种温度下的变形特性;(3)具有研究渗透性、矿物热解过程的变形特性等多种功能;(4)具有在高温下施工钻孔并研究钻孔岩石蠕变特性的功能;(5)主要用于研究岩体的工程特性。采用该试验机进行煤试样在高温高压下的变形特性试验,揭示煤体在高温下的应力–应变特征,特别是高温下塑性强化特性、在塑性阶段无体积膨胀特性,发现其弹性模量随温度的增加呈指数衰减特性。该试验机可用于探索深部采矿、煤炭地下直接液化与气化、地热开采、矿山安全、建筑安全等工程领域深刻的科学规律与自然现象,为能源与资源开发提供原创性的思路与研究方向。

A 20 MN servo-controlled rock triaxial testing system with high temperature and high pressure developed by the authors is introduced.The system is constituted with main loading sub-system,high temperature control sub-system,sample assembling sub-system,and measuring system.The maximum axial pressure and confining pressure are both 10 000 kN.The maximum sizes of tested cylinder sample can be set as large as φ 200 mm×400 mm.The heating temperature can reach as high as 600 ℃.Some related key issues and corresponding solving methods in the test system are also introduced.Compared with high temperature and high pressure test machine of geophysics,the developed test system has some advantages as follows：（1） Larger size sample can be tested,and the volume of the largest sample is 64 times larger than ordinary one and some properties of rock mass can be discovered thoroughly.（2） The servo-controlled system can measure the deformation of sample under different temperatures easily.（3） The thermo-physico-mechanical process of heated rock samples can be measured.（4） Drilling process in deep underground with high temperature can be simulated and investigated.（5） It can be used to study engineering characteristics of rock mass.Certain experimental investigations on coal samples with high temperature and high pressure in the system demonstrated that the plastic properties of the coal sample were enhanced and the Young′s modulus decreased with temperature.The relationship of the Young′s modulus with temperature is found with exponential rule.The testing system can be used to investigate certain scientific natures of deep mining process,direct liquefaction and gasification of coal,geothermal excavation,mine safety,construction safety,etc..