顶管-灰岩异形接触面纯干摩擦试验

Pure Dry Friction Test of Pipe Jacking-Limestone Special-Shaped Contact Surface

岩石顶管顶进初期管节-围岩接触面上无接触介质,对现场顶管摩阻力的影响尤为显著。为研究灰岩在混凝土顶管接触面上的磨损与摩擦系数的内在联系,揭示顶管在长周期顶进状态下摩阻力的变化规律,以在贵州地区广泛分布的灰岩为材料,利用岩石剪切流变试验机进行顶管-灰岩异形接触面纯干摩擦试验。结果表明:随着试验次数的增加,灰岩磨损区域的微凸体不断被剪断、磨平,微观上表现为总磨损质量、面积率的不断上升,宏观上体现为平均表面粗糙度下降带来的摩擦系数的逐渐降低,摩擦系数在前期下降较快、中期下降趋势放缓,后期趋于稳定;将不同滑动次数下得到的摩擦系数分别代入理论经验公式进行实时顶力预估与工程实际较为吻合。研究成果可为接触面微凸体摩擦磨损力学分析模型的建立和顶力预测提供参考。

There is no contact medium on the contact surface between pipe joint and surrounding rock at the initial stage of rock pipe jacking,which has a particularly significant impact on the on-site friction resistance of pipe jacking.In or⁃der to study the internal relations between the wear of limestone on the contact surface of concrete pipe jacking and the friction coefficient,and to reveal the variation law of friction resistance of pipe jacking under long-period jacking,lime⁃stone widely distributed in Guizhou is used as material,and the pure dry friction test of pipe jacking-limestone specialshaped contact surface was conducted by using a rock shear rheological testing machine.The results show that,with the increase of test times,the micro-convex bodies in the limestone wear area are constantly cut and ground,showing a con⁃stant increase of total wear mass and area ratio on the micro level and a gradual decrease of friction coefficient caused by reduced average surface roughness on the macro level,and the friction coefficient decreases faster in the early stage,slower in the middle,and tends to be stable in the later stage.The real-time jacking force predictions obtained by substi⁃tuting the friction coefficients under different sliding times into the theoretical empirical formula are in good agreement with the engineering practice.The research results can provide reference for the establishment of a mechanical analysis model for friction and wear of micro convex bodies on contact surfaces and the prediction of jacking forces.