The Excavation Blasting Technique Of Particularly High And Steep Slope And The Influence On It's Stability

Many large hydropower stations that are being built or to be built are mostly located at the high-mountain-and-gorge areas in the southwest of China. Because of their especial geological conditions the excavation blasting technique research of especially high and steep slope and the stability influence research of blasting become a new problem of our hydropower stations construction. The excavation of especially high and steep slope have large excavation quantities, high height, steep degree of slope, difficult construction arrangement, and the permanent support of the slope synchronous proceed with the excavation blasting, has mutual interference between blasting and support. In order to accelerate construction progress, must adopt wide area deep hole bench blasting method, short-delay blasting network, smooth blasting and presplitting blasting on outline surface. It has a great single blasting scale, long lasting time and they have more circulating blasting times, the safe problem of slope blasting vibration becomes important. The safe problem of slope involve engineering blasting method, engineering geomechanics, explosion mechanics and rock dynamics, construction management course field etc, belong to multi-disciplinary subjiect, have important academic value; It is a urgency key method problem of large hydropower stations construction in the southwest of China relative with the engineering technique. So the research of the problem has important engineering value. The paper adopt the Xiaowan hydropower stations high slope as the background engineering, the slope has 697m on the most high site, is the most high slope in the hydropower stations of world, By measns of analyzing of field ecperimen datas, studied the blasting vibration monitoring and analyzing method, explored the fast excavation method of high and steep slope, annlysed the damage and destruction of blasting on slope rock, studied slope stability influence law and restrain method of blasting on slope rock, presented blasting vibration control means of slope excavation, verified in the experience. The researches have results as following:(1) Fast excavation technique research of especially high and steep slope. Introduced and appraised several common rock excavation methods at the present time, including chamber blasting method, chambering blasting method, deep hole bench blasting, chamber and presplitting blasting technique, on base of them, by means of analyzing and comparing, presented the excavation blasting method comprise of deep holes bench blasting and presplitting and smooth blasting technique, optimized the excavation blasting method: presented a new conception of adopting controlling initiation rows and optimizing total dynamite quantity in one blasting; presented a new idea and new method of optimizing blasting parameters design for making matching between controllable blasting parameters and initiztion time-interval, minished the accumulative damage and destruction of series time after time blasting.(2) Blasting vibration destroy monitoring an analyzing method research. As the first hazard of slope, blasting vibration is always the key research target of people. By measns of analyzing of background engineering, presented a monitoring model that adopted blasting area upper bench slope inner base as controlling position, combinating near area with far area. On analyzing method, adopted the analyzing method made the velocity as the key and accelerated velocity and durative time as the supplementary, the Sadaofsic equation V = Kρ^αe^β(?) was adopted to establish the transmission and decay law of the blasting vibration direction to upper slope, adopted the decay equation to analyse the vibration isolation effectiveness of presplitting blasting, obtained that presplitting blasting vibration isolation rate is 32.5%～44.5% at upper bench, the vibration isolation is fine fine. And subsequent excavation blasting was forcasted and controlled adopting vibration transmission and decay law. The work settled a good base for the congener problem.(3) Numerical simulation research of blasting excavation damage destroy effect. The blasting damage pattern and range of the near middle and far area on the Xiaowan hydropower station high slope was simulated and calculated adopting Ansys-dyna program, the different effects were compared in different bench height, different dynamate quantity, analyzed and summarized the difference between actual test result and calculating result of time and space distributing of the displacement strain damage physical quantity, presented the reduction coefficient of amendment calculating result, presented proof and reference for forecasting experimentation result.(4) Analyzing and appraiseing research of blasting dynamic stability of slope. The stability of slope under blasting vibration was appraised adopting primary stress field cell shearing strength reservation ratio method combine with temporal analyzing method, gained the law of slope blasting buckling safety factor along with the time change, reflected the evolvement course of slope stability in the course of blasting, provided conditions for consummation and optimition of blasting design. The analyzing results proved that the influence of blasting vibration to rock high slope's dynamic stability only was restricted on the surface layer of the slope rock for integrated rock without latency glide face, if the blasting vibration was controlled, the holistic stability of slope was not suffered influence. Glide face S was confirmed according to dynamic and static stress field, the slope stability was appraise adopting shearing strength ratio method of potential glide face S, the analyzing indicated that the safety factor of slope all exceed 1 under the blasting load, the slope is safe.(5) Controlling means and technique research of blasting vibration destroy. Presented that debase vibration should consider blasting position, transmit path, respond of protected target on the base of experimentation and theory analyzing, presented the new method of reasonable optimizing blasting parameter and initiation network for controlling blasting position and cut off transmit path by presplitting sew and damping hole; at the same time reinforced protected aim for improving their aseismatic ability. The all-around controlling method and technique was presented, and verified effectively in practise.In the paper, the academic research is combined with engineering practise, blasting excavation method and technique of especially high and steep slope was improved and developed, the influence rule of excavation blasting on slope stability was analyzed, presented restrain method, the learning thought and method of the paper provides a reference for the congener problem research, the method and technique have directly reference value for the similar engineering.