| Shandong Province belongs to the semi-humid and semi-arid regions of the north.The large number of small reservoirs has a small width of the dam crest and a small amount of anti-seepage engineering(about 30m).Most of the quaternary coverings with particle size ?60mm cause the construction of existing continuous wall grooving equipment and the high cost of temporary construction projects.In view of the above factors,after research and test,Shandong Academy of Water Sciences has innovatively developed a new type of underground diaphragm wall grooving equipment-guide rod rotary cutting grooving machine.This paper introduces the construction technology,working mechanism,technical characteristics and application scope of guide rod cutoff wall.According to the deep foundation pit engineering of Renjiazhuang Station of Jinan Metro,combined with its hydrogeological conditions,as well as its geographical location and surrounding environment,the characteristics of the foundation pit engineering of Renjiazhuang Station were obtained.The characteristics of various anti-seepage and water-stopping technologies are compared.Finally,the guide-bar type rotary cutting is used to construct the seepage prevention wall,that is,the guide rod type anti-seepage wall.This is the first time that this technology has been applied to the foundation pit engineering of metro,which has certain reference significance for similar foundation pit seepage control engineering in the future.The main contents of this paper are as follows:(1)By analyzing the hydrogeological conditions of the foundation pit of Renjiazhuang Station and the characteristics of the surrounding environment,and comparing with other anti-seepage schemes,the anti-seepage scheme adapted to the foundation pit is proposed as the guide-bar anti-seepage wall.(2)Through the selection of different wall materials,choose the appropriate wall material and curing mortar.According to the research experience of the predecessors,the ratio of the curing mortar is proposed.(3)Combined with the example of the foundation pit project of Renjiazhuang Station,the feasibility of this scheme was verified,and the uncondensed solidified mortar was sampled from the slot during the construction period.The laboratory standard culture was carried out for 28 days for impermeability and compression test,and finally opened.During the excavation process,the effect of the core coring is evaluated.(4)Finally,the three-dimensional model was built by FLAC 3D software to calculate the stress and displacement of the foundation pit through the three-way excavation guide-type anti-seepage wall.The engineering practice shows that the new type of guide-type rotary cutting groove anti-seepage technology has achieved good anti-seepage effect in this deep foundation pit project,and added a new construction method for underground continuous wall technology.Compared with the traditional impact drilling,water jetting,grab bucket and vertical multi-head rotary drilling method in the water conservancy industry,the method has the advantages of simple process,low equipment,less auxiliary equipment,high construction efficiency and low unit price of comprehensive construction.The site has good adaptability and many other advantages.At the same time,the foundation pit anti-seepage adopts a new type of guide-type rotary cutting and slotting technology combined with the solidification mortar pouring process,and the slot joint adopts a “set-up method”,and the formed anti-seepage wall body has continuity,uniformity and low modulus of elasticity.And other characteristics,can meet the requirements of the anti-seepage reliability of the deep foundation pit curtain. |
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