流变应力恢复法地应力测试技术.

深部软弱围岩地应力测试的流变应力恢复法原理与技术

刘泉声1，张程远2，朱元广2，蒋景东1

（1武汉大学土木建筑工程学院 岩土与结构安全湖北省重点实验室，湖北武汉 430072；

2

中国科学院武汉岩土力学研究所 岩土力学与工程国家重点实验室，湖北武汉，430071）

摘 要：针对煤矿深部软弱围岩地应力难以测量的技术难题，基于深部围岩在高应力作用下具有强流变性的特点，提出了一种地应力测试新方法——流变应力恢复法地应力测试技术。该方法的提出基于如下假设：在深部巷道软弱围岩中钻孔埋设岩体压应力传感器，由于围岩的强流变特性，传感器附近围岩的应力会随时间逐渐恢复，传感器感受到的应力随时间逐渐上升并最终趋于稳定，可以根据传感器的实测应力来分析围岩的初始应力状态和巷道围岩应力分布的演化。该方法的分析原理是：在巷道围岩的钻孔中某一点，在位于两个完全不同轴的直角坐标系oxyz 和'''ox y z 上放置两个三向岩体压应力传感器A 和B ，通过实测可以得出测点处位于oxyz 和'''ox y z 两个坐标系中的六个正应力分量x σ，y σ，z σ和'x σ，'y σ，'z σ，在已

知oxyz 和'''

ox y z 坐标轴方向余弦的条件下，即可通过应力分析的转轴公式求解得出该测点处位于oxyz 和'''ox y z 两个坐标系中的六个剪应力分量xy τ，yz τ，zx τ和'xy τ，'yz τ，'zx τ，从而确定该测点的应力状态。该方法不需要对岩体的力学性质做出任何假定，也不需要知道被测岩体的本构关系，仅需在测点处放置两个完全不同轴的三向压应力测试传感器，通过应力分析的坐标转换公式求解同一点两个完全不同轴坐标系的六个剪应力分量，从而严密确定一点的应力状态。基于该方法的原理，研发了三向岩体压应力传感器、现场测试的孔内推送定位装置和注浆固定材料技术等一整套技术，并获得中国国家发明专利和澳大利亚国际发明专利。采用理论分析、数值模拟和模型试验相结合的方法，研究了三向岩体压应力传感器埋入围岩介质后的嵌入效应及其自身的感知性能，建立了三向岩体压应力传感器实测应力与围岩介质初始应力状态之间的数学关系。在平顶山矿区深部巷道的现场测试说明了该方法的有效性。

关 键 词：煤矿深部巷道，软弱破裂岩体，地应力；流变应力恢复；三向压力传感器； 嵌入效应。

The Principle, technology and instrument of rheological stress recovery method

for geostress measurement in deep soft rock

LIU Quansheng 1, ZHANG Chengyuan 2, ZHU Yuanguang 2, JIANG Jingdong 1

(1. School of Civil Engineering & Key Laboratory of Geotechnical and Structural Engineering Safety of Hubei Province, Wuhan University, Wuhan, Hubei, 430072, China; 2.State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese

Academy of Sciences, Wuhan, Hubei, 430071, China)

Abstract: For the technical problem that it is difficult to measure the geo-stress in soft and fractured rock surrounding deep roadways in coal mines, a new geo-stress measurement technique called rheological stress recovery method is proposed. It is based on the observations that the soft surrounding rock shows a strong rheological property due to high stress in deep roadways. According to this method, it is assumed that if 3D compressive stress sensors are embedded in the boreholes, the stress of surrounding rock nearby the stress sensors will gradually recover and the stress measured by the stress sensors will gradually increase to a stable value as a result of the strong rheological property of surrounding rock. Then, the in situ stress and the performance of stress distribution can be analyzed by the measured stress. The analysis principle of this method is embedding two 3D pressure cells A and B at a point in the borehole with totally different directions to measure six independent normal stresses x σ,y σ,z σ,'x σ,'y σ,'z σin two different Cartesian coordinate system firstly, and then calculating six independent shear stresses xy τ,yz τ,zx τ,'xy τ,'yz τ,'zx τto determine the stress state at the point by coordinate transformation formula with angels measured in advance. Neither it is necessary to assume the mechanical property nor to know the constitutive equation of the rock. Only two 3D pressure cells have to be embedded nearby with different directions. Based on this method, a three-dimensional vibrating wire 3D compressive stress sensor and corresponding installation devices are developed. The measurement performance of the 3D