| High risk refers to the karst development and large-scale karst tunnel, the presence of large amounts of mud or water in the cave, there is a huge surge in construction and operation of water and mud risk of tunnel engineering, if improper treatment, brings to the tunnel engineering of life or personal injury and economic loss is very heavy, light, led surface collapse, delay the construction period, the submerged tunnel, washed out machines; Heavy casualties, and even lead to scrap the whole project, relocate, serious consequences such as ecological environment deterioration, residents were forced to migration.At present, in the domestic and abroad mainly use grouting method to control the karst water bursting, forming the grouting circle around the tunnel, that will reinforce the surrounding rock to guarantee the excavation face stability and effectively control the tunnel water inflow. The grouting process is mainly affected by three aspects: grouting material characteristics, grouted material characteristics, grouting parameters. The grouting material as the primary factor in the grouting process plays a decisive role to the effect of grouting, and the quality of grouting material is directly related to the tunnel engineering. Tunnel of high risk karst requires grouting material to show performance of good fluidity, underwater anti-washout resistance, high strength, and adjustable thickening time. However, the present grouting material is unable to meet those performances.The subject is based on the research of highway tunnel construction of Baokang to Yichang in Hubei province. Bao Yi Shang Jia Wan expressway tunnel has length of 3865 m, tong body formation of upper Cretaceous Luo Jing Tan group of calcareous conglomerate, developed surface karst, distributed with large number of depressions, sinkholes and funnel, atmospheric precipitation directly through the sinkholes, funnel into the underground, discharged to the deep valley through underground river. Tunnel bedrock outcrop are sedimentary rocks, the tunnel area of grown faults, some huge main structure of city river fault zone; it’s a typical karst tunnel of massive construction risk; Hongyan Temple tunnel is a separated tunnel, maximum length and maximum buried depth in Xiangyang section of Bao Yi expressway, 6678 m length of left, 6739 m length of right. Hongyan Temple tunnel is a typical mountain tunnel through the Permian and Triassic rocks of approximate 3200 m, well developed karst water and accumulation, prone to large geologic disaster. Therefore, this subject tries to develop grouting material for the prevention and control of water(mud) inrush disaster in Bao Yi Expressway Tunnel construction.Based on the relative studies of the domastic and abroad, through theoretical analysis, laboratory testing, test and application, the feedback correction link, and etc. the high risk karst tunnel grouting materials were studied systematically and deeply, concluded a series of research results:(1) The performance design control index of grouting material is putted forward. This subject gives studies of grouting materials, grouting process and grouting components, brief summary on present grouting material by the characteristics of grouting materials, pointing out their advantages and disadvantages, and the performance requirements of general grouting material are summarized, combined with the geological conditions of high risk karst tunnel, the performance requirements and index of grouting material are established.(2) Put forward the combination design method developed in high risk karst tunnel grouting material. According to the analysis of properties of high risk karst tunnel grouting material, taking into account the slurry should have the liquidity, good water resistance under the dispersion, durability, high strength, adjustable thickening time, and safety, economy, environmental protection. Accordingly, the combination of a variety of materials design, as a high risk karst tunnel grouting material, are developed in the laboratory to provide theoretical support and development of ideas.(3) The development of a new high risk karst tunnel grouting material. First to screen the high performance of underwater anti-washout admixture, determining the optimal amount range of underwater anti-washout admixture. The performance indexes by a comprehensive design configuration are consequently tested, coming up with the optimal design of material combination to determine the composition of high risk karst tunnel grouting material. Additionally, the effects of main material content on the slurry, and analysis of the main technical principles of slurry. Finally, recommending the best proportion by the test results.(4) Complete the field test of the new grouting materials. Firstly, introducing the general situation of the project, formulating the field test scheme of grouting, as well as the key points of the construction process and quality control, summary of the field grouting test and the points attention during construction. Field test shows that the grouting material performs well in the project, effectively prevent the tunnel water and mud burst disaster, and reinforce the surrounding rock.New high risk karst tunnel grouting materials has technical characteristics of good fluidity, dispersivity, adjustable thickening time, high early strength, well anti-water performance, it can prevent the mud and other geological disasters, like gushing water and gushing, benefits for the economic and social.This study can be widely applied to highway, railway tunnel construction, river tunnel, tunnel, subway construction project, and etc. as well as the upgrade of tunnel construction level and the insurance of tunnel construction safety benefits. |
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