节理倾向对TBM滚刀破岩模式及掘进速率影响的试验研究

EXPERIMENTAL STUDY OF THE EFFECT OF JOINT ORIENTATION ON FRAGMENTATION MODES AND PENETRATION RATE UNDER TBM DISC CUTTERS

岩体中节理面与掘进方向的夹角是影响TBM破岩速率的一个重要因素。通过试验对TBM滚刀破岩时不同节理面与掘进方向夹角的影响效果进行研究,试验采用2种不同强度的混凝土试块模拟岩石,节理面与加载力夹角α分别为0°,30°,60°和90°。通过试验分析,主要得出以下结论:(1)当α从0°增大至60°时,破岩角β随之增大;当α=90°时,β=33°～50°,与Hertzian裂纹破岩角相近。侧向裂纹与节理方向夹角Δβ随α变化时则保持为40°～70°。对于中间裂纹与节理方向夹角Δγ,当α≤30°时,Δγ=0°～10°,中间裂纹与节理面接近平行;当α≥60°时,Δγ迅速增大,中间裂纹与节理面相交从而形成破岩碎片;(2)节理岩体有3种破岩模式:第一种是从刀具下方破碎区生成侧向裂纹并向自由面或节理面扩展形成碎片;第二种是α≥60°时,中间裂纹向节理面扩展而形成碎片;第三种是α≥30°时,由于节理变形使裂纹从节理面起裂并向自由面扩展从而形成破岩碎片;(3)当α=60°时,破岩速率达到最高值,节理对高强度岩体的破岩影响程度更大。

The joint orientation is a crucial factor which influences the penetration rate of TBM tunneling.Based on laboratory test,the effect of joint orientation on the penetration under TBM disc cutter is studied.In the test,two kinds of concrete with different strengths are adopted to simulate rock sample.The angle α between joint plane and tunneling axis varies from 0°,30°,and 60° to 90°.The main conclusions can be drawn as follows：（1） chipping angle β increases with the increment of angle α from 0° to 60°,and is about 33°-50° when α = 90°which agrees with the Hertzian cone crack.The angle Δβ between side crack and joint plane is about 40°-70° whereas α changes from 0° to 90°.The angle Δγ between median crack and joint plane is about 0°-10° as α≤30°,and arises sharply when α≥60° which makes median crack joints with joint plane to cause chipping.（2） The test results show three possible chipping modes of rock fragmentation：first,the side crack initiates beneath the crushed zone and propagates to free surface or joint plane to produce chipping.Second,the median crack propagates downwards to the joint plane to produce chipping as α≥60°.Third,the crack initiates from the joint plane due to joint deformation and propagates to the free surface when α≥30°.（3） The penetration rate achieves the highest value at α= 60° and joint gives more notable effect on fragmentation of the rock with higher strength.