Study on the unsteady excavation of submarine soft rock mass

一些挖掘机所经历的开挖机理，如抓斗、抓斗等，主要以不稳定开挖为主，其开挖深度随开挖进度而变化。为此，本文对软岩进行了失稳开挖试验，通过一些理论或试验方法阐明了软岩失稳开挖的基本性质。首先根据实验结果分析了刃口受力与位移之间的关系，并对影响这种关系的几个因素进行了研究。然后根据前面考虑的结果对开挖的岩石体积进行了评估。并利用弹塑性本构方程进行了有限元分析，与试验结果进行了对比，验证了切缘附近岩层的破坏形态。最后，将这些研究成果应用于一台真实的挖掘机，以验证本文研究的合理性。研究中主要使用的参数有前角、开挖距离、垂直贯入力和软岩的抗剪强度。除抗剪强度外，其他参数均可从挖掘机的尺寸中获得。因此，本研究的主要目的是(1)根据输入的有关剪切强度的信息，给出挖掘阻力和刃口轨迹的计算公式；(2)通过将其应用于实际挖掘机来检验公式的适用性。

The mechanism of excavation experienced in some excavators, for example grab bucket, clamshell bucket etc, is mainly occupied by unstable excavation, in which the excavating depth is varied with the progress of excavation. Therefore the experiments on the unstable excavation were carried out for soft rock mass and the basic properties were clarified with some theoretical or experimental methods. At first the relationship between the forces applied to cutting edge and the displacements were analysed based on experimental results and several factors affecting the relations were investigated. Then the excavated rock volume was evaluated based on the results of the previous consideration. FEM analysis by use of elasto-plastic constitutive equations were also carried out in order to compare with the experimental results and to check the failure pattern of rock ground in the vicinity of the cutting edge. Finally these research results are applied to a real excavator to check the appropriateness of this study. Parameters mainly used in this study are rake angle, excavating distance, vertical penetration force and shear strength of soft rock. The para-meters except the shear strength can be obtained from the size of the excavator. The main targets of this study were therefore (1) to give formula on excavating resistance and the locus of cutting edge on the basis of the input information about the shear strength, (2) to check the appropriateness of the formula by applying them to a real excavator.