The Technology Research Of Rotary Drilling Combined With Percussive Drilling Into The Hard Rock In Diaphragm Wall

In the hard rock strata, there are many difficulties in the construction technology of underground continuous wall. Although traditional percussive drilling technique is applicable to a variety of hard rocks, there is a low efficiency of construction, such as mud pollution and other issues. In recent years, the rotary drilling rig with its outstanding advantages of efficiency and environmental protection is widely used in many infrastructure constructions. Rotary drilling technique also represents today’s advanced level of drilling, however the application of rotary drilling rig in the hard rock strata is still developing. Therefore, the study of rotary drilling technology in hard rock strata has a strong practical significance.This paper relies on the Yuancun station project of the Guangzhou Metro Line 21 to study rotary drilling technology, the main contents are as followed:(1) Discribing elaborately about a new technique of rotary drilling into the hard rock strata, otherwise, the technicians tested three comprehensive drilling techniques and made a technical and economic analysis,proving that rotary drilling technique combined with percussive drilling technique can effectively shorten the construction period, but you have to increase the cost.So, you need to consider the cost, time and other factors to select.(2) For sticking and other issues encountered on sites when the rotary drilling rig is working, trying to study the rock crushing mechanism by reading the relevant literature to explore the pressure distribution of rock under the drilling teeth of different shapes,then summarizing crushing features of rock under the static load, the dynamic load and the composite load.At last, a new way of loading can be proposed according to the conclusions above.(3) Using ABAQUS to simulate the process of a single pick drilling three hard rock samples, the cutting angle of the pick need to be adjusted in a certain range.By introducing the concept of cutting power ratio, comparing the values of cutting power ratio to give a recommended value of the optimum cutting angle.