Abstract
To ensure the safe and efficient excavation of ultradeep foundation pits in a complex urban environment, the ultradeep foundation pit excavation project of Liuguangmen Urban Complex in Guiyang City was taken as the study point. A high-efficiency blasting method was proposed for the excavation of vibration-isolating slot and electronic detonators, and a three-dimensional spatial calculation model of the foundation pit structure was established. In addition, the field test and numerical simulation of the blasting vibration were developed. The feasibility of the high-efficiency blasting method was demonstrated, and the propagation law of the dynamic response characteristic parameters of the structure was explored using an electronic detonator and vibration-isolating slot. The results show that the electronic detonator carried out peak shaving within the group, unloading waves between the groups, and the blocking effect of the vibration-isolating slot, and all these effectively reduced the peak stress and peak particle vibration velocity, evenly distributed the vibration velocity, and guaranteed the safety of the surrounding existing buildings, proving the feasibility of the efficient blasting method. There is a “wall effect” at the supporting pile, whose propagation velocity is lower than that inside the rock mass, and the PPV is radial X > tangential Y > vertical Z. The peak values of stress, strain, and PPV all decrease with increasing supporting pile height, and there is an inflection point at 20 m. The internal nodes of the pile reciprocate without sharp change and failure in displacement. The peak displacement of different nodes is in the order X > Y > Z with increasing pile height, and the maximum peak value is 0.08 mm.
Highlights
To ensure the safe and efficient excavation of ultradeep foundation pits in a complex urban environment, the ultradeep foundation pit excavation project of Liuguangmen Urban Complex in Guiyang City was taken as the study point
There are a few reports on the evolution law of the dynamic response characteristic parameters under high-efficiency blasting effect of excavation vibration-isolating slot and electronic detonator initiation
Based on the ultradeep foundation pit excavation in the complex environment around Liuguangmen, Guiyang city, an effective blasting model of vibration-isolating slot and electronic detonator was successfully established, the vibration response characteristic test and dynamic response numerical test were carried out, and the dynamic response characteristics of existing structures under the blasting action of 6 kg single-hole charge were studied. e outcome of this study is as follows: (1) e vibration velocity and stress of the structure are in a safe range under the action of excavation vibration-isolating slot and electronic detonator initiation
Summary
After the pile body reaches the design strength and the anchor cable is gradually applied to prestress, the retained rock mass was broken and cleared mechanically. In terms of the adverse effects of blasting of this project, vibration, the main control object, was mainly controlled by the single-hole charge, the initiation network, and the vibration propagation path. According to Sadov’s empirical formula for vibration calculation [17] and similar construction experience, the blasting area and the mechanical broken area (rock mass within 15 m of the adjacent pile) are divided and the single-hole charge is strictly controlled. E design of the detonation network ensures that the blasting time of the hole is independent of each other, avoids vibration superposition, and controls the single duration of vibration. To ensure the safety of the surrounding structures, the slot was set with a depth of 4 m, a width at the top of 4 m, and a width at the bottom of 3 m
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
