RESEARCH AND APPLICATION OF MJS PRE-REINFORCEMENT CONSTRUCTION TECHNOLOGY FOR SHIELD PASSAGE IN WATER-RICH SAND STRATUM THROUGH UNDERGROUND STRUCTURE GROUP PILES
The MJS pre-reinforcement construction technology of shield passage through water-rich sand layer of underground structure group piles includes technical principles,implementation ideas and concrete construction steps.It is composed of three links:horizontal pilot hole of dense pile group,sand loss control of horizontal pilot hole of water-rich sand layer,and conventional horizontal MJS grouting reinforcement.The technology uses pilot drill pipe+outer casing to carry out horizontal pilot holes to realize the crossing of column piles and high-strength pipe piles,as well as long-distance hole formation in water-rich sand layer.In the process of pilot holes,double liquid grouting is used to reinforce the grouting line once.Meanwhile,flange plate+check valve installed at the hole is used to control the sand loss and reduce the influence of pilot holes on underground structures and surrounding environment.After the completion of the pilot hole,the conventional MJS grouting reinforcement is carried out to achieve the pre-reinforcement target,and the concrete MJS pre-reinforcement construction steps are formed to guide the construction of the shield channel under the underground structure group pile with water-rich sand layer,which greatly reduces the impact on the underground structure and the surrounding environment,reduces the waste of mud,improves the construction efficiency,has good economic and social benefits,and has good popularization and application value.
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