深部复合岩层TBM滚刀与围岩相互作用机理研究

In deep mixed rock stata, because of the interlaced existence of soft rock and hard rock in high in-situ stress state, it is adverse to fragment rock for disc cutter. Meanwhile, tunneling efficiency is sevely impacted and risk accidents are probably caused. In order to improve rock fragmentation efficiency and avoid risk, it is necessary to study on the interaction mechanism between TBM disc cutters and surrounding rock. In view of the difficulty and lack of representive of sampling in field, the mould which is used to prefabricate spcimens of mixed rock strata-like material is developed. Confining pressure, angle of rock strata, the ratio between strength of hard rock and strength of soft rock and disc cutter spacing are taken into account during the experiments. In order to optimize the experimental scheme, orthogonal experiment design method is used to design the experiments. Spcimens of mixed rock strata-like material are prefabricated according to the design. Then the experiments of rock fragmentation by three disc cutters are completed one by one. Based on the data and results of the experiments, the mechanism of crack propagation is going to be revealed and numerical simulation by DEM will also be used to analysed the mechanism. The results derived by DEM can be used to verify the expriments. Based on the expemental data, the specific energy of each specimen in different penetations are analysed and calculated. Then considering all the experimental and calculated results, model of optimum cutter spacing will be establised by nonlinear regression method. The research findings can provide technical support and scientific basis for cutter head design in deep mixed rock strata.

深部复合岩层中，由于在高地应力下呈现软岩、硬岩交错出现，对TBM滚刀破岩非常不利，严重影响了掘进效率并且有可能触发风险事故。为了提高破岩效率，规避风险，研究深部复合岩层TBM滚刀与围岩相互作用机理很必要。针对现场复合岩层取样困难及代表性不强的问题，研制类复合岩层试样浇筑模具。破岩试验中考虑围压、岩层倾角、硬岩与软岩强度之比及刀间距等因素的影响，为了优化试验方案，采用正交试验设计方法确定试验次数。根据设计的试验预制试样，然后在试验平台上依次完成设计的三滚刀破岩试验。依据试验数据及观测结果探索裂纹扩展机制并使用离散元进行数值模拟对试验结果进行验证。在采集的试验数据基础上，分析计算各试样不同贯入度下的比能，综合所有试验及分析计算结果采用非线性回归方法建立最佳刀间距预测模型。研究成果可以为复合岩层中TBM刀盘设计提供技术支撑与科学依据。

深部复合岩层中，高地应力下呈现软岩、硬岩交错出现，对TBM滚刀破岩非常不利，严重影响了掘进效率。为了提高破岩效率，研究深部复合岩层TBM滚刀与围岩相互作用机理很必要。鉴于上述原因，本项目以TBM在基础设施建设中的应用为背景，开展复合岩层中TBM与围岩相互作用研究，主要内容如下：（1）通过离散元数值模拟方法探讨了岩层产状、围压、软硬岩切割比例对破岩效率的影响；（2）采用室内破岩试验和数值模拟研究了软硬岩切割比例对裂纹扩展及最优或合理的刀间距影响；（3）使用三维离散元数值法对不同围压下各因素对最优刀间距影响进行了深入分析；（4）采用三维离散元方法探讨了复合岩层中合理的TBM掘进方向。.主要得到以下成果：（1）岩层倾角及层理对破岩比能的大小几乎没有影响，滚刀切割软岩、硬岩的比例对破岩效率有一定影响。围压和岩石强度对裂纹扩展有抑制作用，围压和岩石强度越大，破岩效率越低。（2）试验中选取的砂岩、花岗岩形成的复合岩层，其软硬岩切割之比为4：6，s/p（s:刀间距，p：贯入度）在12.86至14.3之间变化时，破岩比能最低。数值模拟结果和试验基本一致。（3）在不同的软硬岩切割比例下，合理的s/p范围有差别；项目中选取的砂岩和花岗岩不同复合比例时，合理的s/p在不同复合比例之间有个共同的交集，即s/p=14。（4）软硬岩切割比例的改变对破岩比能影响较大，但对合理的s/p的影响较小。不同复合岩层的合理或最优s/p有较大差别，没有统一的数值，但同一复合地层中可以获得统一的合理的s/p。（5）从卡机控制的角度而言，复合岩层中，沿倾向掘进较逆倾向掘进更有利，岩层倾角较大时，对卡机控制更有利。以上研究成果可以为复合岩层中TBM刀盘设计和施工提供参考。