Cognition, Application and Discussion on Shaped Charge Hydraulic Smooth Blasting Technology

In the past, the main method of tunnel excavation in China was drilling and blasting, but the biggest shortcoming of the traditional drilling and blasting method is that it is easy to cause serious overexcavation and underexcavation. At the same time, the operation cycle time of this method is long, which leads to a serious waste of resources. Not only that, a large number of toxic gases and dust produced after blasting also do harm to the health of construction workers. So this is an urgent need for a new construction technology to solve this worldwide problem. In this situation, the leading experts in the field of tunnel, "The survey and design master of China" Shi Yuxin, Liu Pei, and well known expert in explosion field, yan-sheng ding, professor Chen Chengguang and Gu Yicheng, the experts group, cooperate with The Fifth Branch of China Railway 18th Bureau in northwest project management department, developed a new technology. This technology has passed the appraisal of scientific and technological achievements organized by Tianjin Science and Technology Commission, which is shaped hydraulic smooth blasting technology. The comprehensive evaluation of the technology is "international leading" level.This paper is mainly aimed at the drawbacks of drilling and blasting construction,combined with the author's cognition and discussion on the introduction of the new technology of cumulative hydraulic blasting and the practical application effect in the tunnel excavation process of the fourth company of China Railway 14th Bureau Group in the second division of the 9th bid section of Zhangjihuai Railway in Huainan Province.

Numerical Simulation of Rock Mass Structure Effect on Tunnel Smooth Blasting Quality: A Case Study

Taking the Zigaojian tunnel, Hangzhou–Huangshan high-speed railway, China, as background, the rock mass structure effect on smooth blasting quality was studied. Four rock mass structures were determined on the basis of the information collected on the tunnel site. Smooth blasting finite element models were established using LS-DYNA. The accuracy of the numerical calculation model was verified by comparing the overbreak and underbreak between the numerical simulation and monitoring. Orthogonal numerical test was used to study the rock mass structure effect through single factor and main effect analysis methods. With the decrease in rock mass integrity, the smooth blasting overbreak of tunnels with massive integrity structure, massive structure, layered structure, and cataclastic structure increased. For massive integrity structure and cataclastic structure, the peripheral hole spacing should be emphatically considered. Meanwhile, in massive structure and layered structure, the included angle and spacing of structural planes had a great influence on the smooth blasting quality. The research results could provide a reference to improve the quality of similar tunnel smooth blasting.

Research on Construction Control Technology of Large-Span and Small Clear Distance Underpass High-Voltage Line Tunnel

Hanping tunnel is a control project of national highway 310 Dahejia to Qingshui highway project. It needs to cross a 330kV high-voltage transmission line under the condition of small clear distance, which requires high construction requirements. In view of the difficulties such as shallow buried depth of tunnel and small clear distance between tunnel and tower of high-voltage line, multiple excavation blasting method is adopted, and smooth blasting, charge quantity control and damping hole setting are comprehensively used to reduce the impact on the tower and structure of high-voltage line. In order to ensure the smooth progress of the project, the large-scale finite element analysis software is used to simulate the whole excavation project. The influence of the full-section method and the middle partition wall method (CD method) on the surrounding rock and the high-voltage electric tower is compared. It is found that the CD method can effectively control the displacement of the surrounding rock and the tower on it and the uneven settlement.

The Efficiency of Large Hole Boring (MSP) Method in the Reduction of Blast-Induced Vibration

Drill and blast is the most cost-effective excavation method for underground construction, however, vibration and noise, induced by blasting, have been consistently reported as problems. Cut blasting has been widely employed to reduce the blast-induced problems during underground excavation. We propose that the large hole boring method using the state-of-the-art MSP (Multi-setting smart-investigation of the ground and pre-large hole boring) machine (“MSP method”) can efficiently improve vibration reduction. The MSP machine will be used to create 382 mm diameter empty holes at the tunnel cut area for this purpose. This study assessed the efficiency of the MSP method in reducing blast-induced vibration in five blasting patterns using a cylinder-cut, which is a traditional cut blasting method. The controlled blasting patterns using the MSP method demonstrated up to 72% reduction in blast-induced vibration, compared to the base case, Pattern B, where only cylinder-cut and smooth blasting method were applied. Therefore, the MSP method proves to be a promising alternative for blasting in sensitive urban areas where non-vibration excavation techniques were initially considered. Geological characteristics of 50 m beyond the excavation face can be acquired through the proposed real-time boring data monitoring system together with a borehole alignment tracking and ground exploration system. The obtained geological information will be a great help in preparing alternative designs, and scheduling of construction equipment and labour during the tunnel construction.

Development and Application of an Intelligent Evaluation and Control Platform for Tunnel Smooth Blasting

Many tunnels around the world are still being constructed by drilling and blasting because these methods have an unmatched degree of flexibility relative to machine excavations using tunnel boring machines. At present, a large gap exists between evaluation theory and the control application of tunnel smooth blasting (TSB) quality. In this study, a handheld mobile platform that is based on the Android system and is written in the Java language is proposed to evaluate and control the performance of TSB. The function of this handheld mobile platform mainly includes data input, data modification, data deletion, weight setting for smooth blasting evaluation, smooth blasting quality assessment, and smooth blasting quality control. Using the proposed mobile platform, end users can evaluate and control TSB quality after each blast. The proposed handheld mobile platform is also applied to the real case history of line 6 in Guangzhou, China.

Intelligent Control of Smooth Blasting Quality in Rock Tunnels Using BP-ANN, ENN, and ANFIS

The construction quality of tunnel smooth blasting is difficult to control and fluctuates greatly. Moreover, the existing technology, which relies on the visual observation, empirical judgment, and artificial control, has difficulty meeting the requirements of tunnel smooth blasting construction quality control. This paper presents the construction principle of a tunnel smooth blasting quality control system, introduces a process quality control technology into quality control of tunnel smooth blasting construction, designs a framework for the tunnel smooth blasting quality control system, and collects control index data based on field investigation, expert consultation, and experimental research. By using the methods of index utilization rate statistics, gray correlation analysis, and principal component analysis, this paper primarily elects and selects the control indexes; establishes the tunnel smooth blasting quality control index system; constructs a comprehensive optimization control model of tunnel smooth blasting quality using back propagation artificial neural network (BP-ANN), Elman neural network (ENN), and adaptive neuro fuzzy inference systems (ANFIS); and studies the tunnel smooth blasting quality control system. The following are the conclusions of this study: (1) This paper presented a method of constructing a tunnel smooth blasting quality control index system and established this system with seven criteria layers, namely, geological conditions, explosive properties, borehole parameters, charge parameters, method of initiation, tunnel parameters, and construction factors, as well as a total of nine indexes. (2) The comprehensive optimization control model of BP-ANN, ANFIS, and ENN for tunnel smooth blasting quality was established. (3) The uniform design method was used to optimize the blasting parameters of the tunnel section, which needs to be controlled, and verify that the construction of these comprehensive optimization control models can change the focus of tunnel smooth blasting quality control from the traditional single index control method into a dynamic, intelligent, pluralistic, and integrated control technology.

Execution of Safe Blasting Under Adverse Conditions of a Powerhouse Complex: A Revisit to Sardar Sarovar Project, India

When the excavation of the underground powerhouse of the Sardar Sarovar Project, India was nearly complete, cracks were observed on the upstream and downstream walls of the powerhouse, and the installed instrumentation readings sounded an alert for the instability of the powerhouse cavern that could possibly derail the project, further excavation in the powerhouse cavern was halted. After completing stabilisation measures, the remaining underground excavations by drill and blast method were to be completed. This paper revisits case studies of controlled blasting for the remaining excavations, namely a construction ramp, turbine pits, draft tube tunnels connecting the powerhouse, and the concrete plugs erected at the exit ends of the draft tube tunnels. To ensure overall stability around the excavations, blast vibration was controlled by planning the excavations in proper sequences. The damage outside the planned line of excavations was controlled by adopting modified line drilling/smooth blasting techniques. The details of the sequence of excavations, drilling and blasting parameters, compiled from previous publications, are presented in this paper. This paper also describes the reasons why concrete plugs were erected in the draft tube tunnels, the details of the concrete plugs, the optimised drilling and blasting procedure for safe removal of the plugs, and the method adopted to quantify the damage.

Frequency Spectrum and Wavelet Packet Analyses of Blasting Vibration Signals for Different Charge Structures in Blasting Peripheral Holes

Based on the blasting principle of the cutting seam cartridge, smooth blasting with the charge structures of the usual cartridge and cutting seam cartridge has been designed and implemented, respectively, for different peripheral holes in the same face. Meanwhile, the blasting vibration has been monitored. Through the analysis of the frequency spectrum of blasting vibration signals, it is found that the maximum blasting vibration velocity of the cutting seam cartridge charge is lower than that of the usual cartridge charge, from 0.21 m/s to 0.12 m/s. Moreover, the blasting energy distribution is more balanced. Especially in the low-frequency part, the blasting energy is less, and there is a transferring trend to the high-frequency part, which shows that the cutting seam cartridge charge has a better optimization effect. Furthermore, using wavelet packet analysis, the cutting seam cartridge charge could effectively reduce the energy concentration in the low-frequency part. The energy distribution is much more dispersed, and the disturbance to the structure could be less, which is conducive to the stability of the structure. According to the blasting effect, the overbreak and underexcavation quantity at the cutting seam cartridge charge is better than that at the usual cartridge charge.

A New Technology for Smooth Blasting without Detonating Cord for Rock Tunnel Excavation

In this paper, the aim is to achieve safe, rapid excavation of an extra-long, large-cross-section highway tunnel in Eastern Tianshan, as well as to reduce production costs, simplify production processes, reduce cycle time, and improve production efficiency. In this study, we explored a new technology for smooth blasting without a detonating cord. A series of sympathetic detonation experiments were conducted in the tunnel face to determine critical distances. The critical distance for No. 2 rock emulsion explosive under blasthole constraints was successfully measured to be approximately 1.0–1.1 m. Based on the critical distance, a new charging structure was designed for tunnel excavation. To assess the influence of the new charging structure on blasting performance, its economic benefits, and its feasibility, full-section tests were performed in the East Tianshan Tunnel. The application of the new charging structure produced good smooth blasting results. It not only simplified the charging process and produced smooth blasting without detonating cord in peripheral holes, but also guaranteed normal excavation, an appropriate tunnel profile, and reasonable overbreak and underbreak volumes. This had remarkable economic benefits and possesses better promotional value.