岩石高温高压两刚一柔型真三轴时效力学试验系统研制与应用

A true triaxial time-dependent test system with two rigid and one flexible loading frame for rock under real-time high temperature and high pressure and its application

为研究深部地下工程岩体在高温高压条件下开挖响应问题,自主研制岩石高温高压两刚一柔型真三轴时效力学试验系统。该系统主要包括用于施加最大主应力(σ_(1))和中间主应力(σ_(2))的刚性应力加载系统,施加最小主应力(σ_(3))的柔性应力加载系统,温度伺服控制系统及可扩展部分;在σ_(1)和σ_(2)方向上刚性加载力最高2000 kN,σ_(3)方向柔性加载的最大压力为70 MPa。该系统设计采用50 mm×50 mm×100 mm的标准岩石试样,可在最高250℃的长时高温下进行真三轴、蠕变以及循环加卸载等多种应力路径试验。应用该系统研究高温(60℃,100℃,150℃,200℃)高压(σ_(2)=30 MPa,σ_(3)=20 MPa)条件下北山花岗岩强度与变形特征、高温条件下锦屏大理岩真三轴蠕变行为。结果表明,北山花岗岩峰值强度和弹性模量随温度升高而呈现出先增大后减小的趋势,转折点出现在150℃。锦屏大理岩80℃下真三轴蠕变曲线可明显观察到衰减蠕变、稳定蠕变和加速蠕变过程。该系统为认知高温高压下岩石真三轴力学特性提供了一种新的有效手段。

In order to study the excavation response of deep underground engineering rock masses under high temperature and high-pressure conditions,a true triaxial rheological test system of the“two rigid and one flexible”type was independently developed for carrying out experiments on rocks under high temperature and high pressure.The system mainly includes two rigid stress loading components respectively for applying maximum principal stress(σ_(1))and intermediate principal stress(σ_(2)),a flexible stress loading system for applying minimum principal stress(σ_(3)),a temperature servo control system and some extensible parts.The rigid loading force in the directions ofσ_(1) andσ_(2) is up to 2000 kN and the maximum pressure of the flexible loading in theσ_(3) direction is 70 MPa.The system is designed for a standard rock sample with three edges respectively of 50 mm×50 mm×100 mm,and can perform various types of high-temperature stress loading tests such as true triaxial,creep,and cyclic loading and unloading.The system was used to study the strength and deformation characteristics of Beishan granite under high temperature(60℃,100℃,150℃,200℃)and high pressure(σ_(2)=30 MPa,σ_(3)=20 MPa)true triaxial loading conditions,and the true triaxial creep behaviour of Jinping marble under high-temperature conditions.The results show that the peak strength and elastic modulus of Beishan granite first increase and then decrease with increasing temperature,and the turning point appears at 150℃.The true triaxial creep curve of Jinping marble at 80℃obviously exhibits the attenuation creep,stable creep and accelerated creep process.The system provides a new effective method for characterization of the true triaxial mechanical properties of rocks under coupled high temperature and high-pressure condition.