Deformation Characteristics Of Deep Excavations Under The Reinforcement Of Mixing Pile And Diaphragm Wall

With the construction of new areas such as Guangdong-Hong Kong-Macao Greater Bay Area and Xiong'an New Area,the traffic capacity of these developed cities has been further increased,and the transportation capacity has been more and faster and more convenient,For Shenzhen,which is at the forefront of reform and opening up,it plays a very important role in the planning of Guangdong,Hong Kong,Macao and Dayan,so the construction of the whole Shenzhen subway is speeding up on a large scale.Based on the deep foundation pit project in yitian parking lot of shenzhen metro line 10,the reinforcement and support scheme of foundation pit is studied in this paper,The concrete research content includes: The foundation reinforcement of the foundation pit and the reinforcement scheme of the trench of the connecting wall are analyzed and compared,In this paper,the method of using cement-soil mixing pile to reinforce the passive soil area in the foundation pit is put forward,and this scheme is used to support the trenching process of the connected wall.Through the analysis of the monitoring data after the reinforcement and support scheme is adopted,the actual performance of the whole support scheme is verified,In addition,FLAC3 D numerical simulation was used to simulate the process of trenching of underground continuous wall supported by cement-soil mixing pile,and the deformation of the wall was compared with that supported by mixing pile in two cases.After the completion of the process simulation,the foundation pit excavation under the condition of the support system composed of retaining piles and ground walls was modeled and analyzed,In this paper,the deformation of foundation pit is compared with that of single wall and retaining pile and ground wall,and the supporting performance of mixing pile in the process of trenching and excavation is analyzed.The most important research results in this paper include the following parts:In order to understand the reinforcement performance of geogrids in seasonally frozen soil,the main research contents and research results in this paper include the following parts:(1)Comparison and selection of several consolidation methods for soft ground,Finally,according to the geological conditions and economy,reliability,length of construction,etc.of the deep foundation pit engineering in yitian parking lot,the foundation reinforcement of the foundation of the deep foundation pit is selected from the methods of rotary jet grouting pile,cement mixing pile and high pressure grouting,etc.in the paper,the foundation of the deep foundation pit is reinforced by the cement soil mixing pile is selected,1m from the bottom of the foundation pit to the weak stratum is selected to reinforce depth of the pile body size,The diameter of the mixing pile is 650 mm,the center distance of the pile is 800 mm,and the "well" pattern is arranged.Two rows of?650@ 500 cement mixing piles are chosen to reinforce the two sides of the joint wall,Its depth is 1m below the mucky clay soil layer.Finally,through the analysis of monitoring data,the reinforcement performance of the reinforcement scheme in the ooze soft soil foundation pit is good.(2)The trenching of cement-soil mixing piles in the retaining wall has significantly reduced the settlement and displacement of the whole soil mass during excavation,mud protection,concrete pouring or concrete forming process etc,The deformation distribution of the whole floor-connected wall is more reasonable,and the floor-connected wall is more secure at the same time.(3)Compared with the single retaining wall,the deformation of the foundation pit can be by the support system composed of cement-soil and underground continuous wall.In the process of excavation of the foundation pit,The deformation values such as settlement,displacement of the wall top,axial force of cross-brace and uplift of the foundation pit under the condition of mixing pile support,have been reduced obviously,Therefore,the cement-soil mixing pile,which is set for the purpose of retaining the trench of the retaining wall,can improve the deformation degree of the foundation pit and make the excavation process more safe in the course of the following excavation.