The Impact to Bridge Pile Foundation from Drilling and Blasting in Metro
|School||Beijing Jiaotong University|
|Course||Bridge and Tunnel Engineering|
|Keywords||Loose circle Drilling and blasting method Bridge Pile Foundation Chongqing subway VI line|
Railway and subway career in the rapid development of our country, and through the hard rock geology is often encountered in the process of the construction of the railway and subway compared to the tunnel boring machine, drilling and blasting method due to geological conditions adaptability open digging low cost. Therefore particularly suitable for hard rock tunnel, crushing rock tunnel boring and short tunnel. Increasingly dense urban roads, bridges, buildings, increasing the probability of the subway beneath the bridge, Chongqing subway on the 6th line wear Wong Nai Pang Interchange for example, focuses on the drilling and blasting method subway beneath the bridge piles based technical analysis. Drilling and blasting method in the construction process, how to reduce the disturbance to the surrounding rock is a key technology, in this article from the point of view of the loose circle to study the construction of the drilling and blasting method of surrounding rock disturbing effect. The loose circle from the causes can be divided into two parts: the the cavern size effect loose circle and blasting dynamic pressure loose circle. Firstly summarized summarizes the existing loose circle theory of the generation age of the various theories and theoretical points, the advantages and disadvantages of the various theories, and then focus on the formation mechanism of the loose circle with a clearer understanding also provides a better mechanical model elastoplastic mechanical method, use this method to derive the range of the loose circle of size effects in ideal natural rock mass in a circular cavern, and discuss the main factors influencing the loose circle. Experimental study on combination of of blasting dynamic pressure loose circle, as well as some of the construction site of the measured data on the basis of this article blasting explosives in the study rocks mechanism summarizes the construction of the drilling and blasting method to cause the law of the expansion of loose circle, given the pressure loose Blasting the approximate ratio of the loose circle of the ring and the size effect. Combined with a risk point of the Chongqing Metro Line 6, the dynamic pressure corrected by theoretical formula and blasting, a loose circle the size of calculated there, at the the tunnel top of the bridge pile foundation exists when rock stress and analytical methods for solving . Using the finite element method to simulate the construction process, focusing on the development of law and the scope of analysis of a tunnel beneath the bridge pile foundation loose circle, including single-hole excavation, both left hole the right tunnel excavation as well as dual-hole at the same time open dug plastic circle developments in these three cases. While the top of the rock mass stress redistribution and settlement of the internal forces of change as well as the bridge pile.