INTERNAL PRESSURE DECREASING METHOD ON TUNNEL EXPERIMENT AND SUITABLE PATTERN FOR TUNNEL ROCK BOLT.

迄今为止，采用外压法进行了锚杆模态试验。该方法在无应力基岩中设置隧道，在基岩周围施加外压。在实际中，隧道是在基岩中开挖的。现在更认识到，我们采用内压递减法。内压产生仪设定好后，加外压，内压发生反应。通过减小该压力来模拟开挖。隧道实验设备为平面应变式，尺寸为1.4×1.4×0.3m，模型隧道直径为40 cm。在这些实验中，模型基岩与隧道试验设备之间的摩擦破坏了应力传递，隧道壁面内压没有像预期的那样发生。因此，我们使用聚四氟乙烯阀座和液体石蜡来减少它们之间的摩擦，但摩擦仍然存在，内部压力小于外部压力。因此，我们必须主动增加一些内部压力的油单位。我们做了以下工作。(1)内部压力产生仪的研制（φ=40 cm，深度=30 cm）。(2)利用聚四氟乙烯坐垫和液体石蜡对模型基岩与隧道试验设备之间的摩擦系数进行了实验研究，并对考虑摩擦的隧道壁面内压控制方法进行了理论研究。(3)建立隧道试验内压降低方法。(4)铝杆φ=4 mm，长度=6、12、24 cm的几种锚杆模式与非锚杆模式在各模式锚杆总长度相等的情况下的试验对比。(5)在侧压系数k=1.0时，短锚杆的锚固效果优于长锚杆。

Up to this time rock-bolt pattern test has been experimented by external pressure method. In that method, tunnel was set in bedrock unstressed, and external pressure is added around bedrock. In actual, tunnel is excavated in bedrock earth-pressured. Now more realizing, we adopt internal pressure decreasing method. After setting the internal pressure generate instrument, external pressure is added and internal pressure occurs in reaction. Excavation is simulated by decreasing this pressure. The tunnel experiment equipment is plane strain type, and its size is 1.4×1.4×0.3m and the model tunnel diameter is 40 cm. In these experiment , friction between model bedrock and tunnel test equipment injures stress transmission and internal pressure at tunnel wall don't occur as expected. So we use Teflon seat and liquid paraffin between them to cut friction, but some mount of friction remain and internal pressure become smaller than external. So we must add some mount of internal pressure actively by oil units. We did followings.(1) Development of the internal pressure generate instrument (φ=40 cm, depth=30 cm).(2) Experimental study of the friction coefficient using Teflon seat and liquid paraffin between model bedrock and tunnel experiment equipment and theoretical study of the control method for internal pressure at tunnel wall considering friction.(3) Establishment of internal pressure decreasing method on tunnel experiment.(4) Comparing experiments with several rock-bolt patterns (aluminum-bar φ=4 mm, length=6,12,24 cm) in the condition total rock-bolt length of each pattern is equal, and non bolt pattern.(5) Short rock-bolt is more effective than long one from the results of experiments on lateral presser coefficient k=1.0.