Study On Uneven Settlement Control Of Large Shaft Sinking Derrick Foundation

In the process of development and utilization of underground space,shaft hoisting system is an important lifting structure for normal shaft construction and production,and it is an important part of the whole lifeline project.Many large and deep vertical shaft projects are faced in actual projects,During the construction process,the uneven settlement of the derrick foundation will bring a lot of economic and security problems to the project.When the foundation of the derrick foundation is located in complex geological conditions,more stringent control requirements are put forward for uneven settlement of derrick foundations.In this paper,the reinforcement of the derrick foundation of No.1 Ventilation Shaft in Fo Ling Tunnel is taken as the engineering background.Combined with theoretical analysis,grouting experiment research,numerical simulation analysis,engineering monitoring and other methods,the uneven settlement of the derrick base on the basis of different attributes are analyzed,and the uneven settlement of the derrick foundation is also studied.The main research content and conclusions are as follows:?1?The 1#ventilation shaft of the Fo Ling tunnel is located on the basis of 4properties of the derrick foundation,one of the derrick base stands directly on the original rock,and the other two derrick pedestal stands on the foundation of blasting waste fill backfill,there is also a junction between gangue backfill foundation and original rock foundation,in the operation of the lifting system,due to the effect of overlying load and self weight of the structure,the derrick foundation will produce different degrees of settlement at the base of the base,which affects the normal work of the project.?2?It can be seen from the numerical simulation results,when the refuse backfill foundation is not treated,the maximum settlement value of the derrick base is 4.5cm,and the phenomenon of uneven settlement is remarkable;After grouting to reinforce the backfill foundation of the gangue,the maximum settlement of the derrick base is reduced to 2.59cm,compared with the backfill foundation without any treatment,the maximum settlement is reduced by 43%;After the combined consolidation,the maximum settlement of the derrick foundation is reduced to 1.8cm,which is reduced by 60%,and It is possible to control the uneven settlement of the foundation economically and reasonably.?3?Through the experimental study,it is concluded that the cement water glass double liquid grouting material can control the water separation rate of the slurry well and improve the stability of the slurry.The gelation time of cement-water glass slurry is influenced by the volume of water glass and the ratio of water to cement.When the amount of water glass is fixed,the greater the ratio of water to cement,the slower the gel speed of the slurry and the longer the time;When the water cement ratio is fixed,the gelation time of the slurry reduces with the increase of the glass content of water glass when the content of water glass is less than 15%.When the amount of water glass is higher than 15%,the gelation time of the slurry gradually tends to a certain value with the increase of the use of water glass.?4?Grouting experiments show that the strength of cement sodium silicate slurry is affected by the content of sodium silicate.When the content of sodium silicate is 15%,the uniaxial compressive strength of cement sodium silicate slurry is the highest;When the amount of water glass is more than 20%,there are obvious cracks in the curing process of the stone body,and with the increase of time,the crack continues to go deep into the stone body,until it is completely destroyed.?5?The result of the theoretical calculation is as follows:The maximum deflection value of the cantilever beam bending member connected to the derrick foundation base and the locking plate is 1.44cm.According to the specifications,the maximum allowable deflection of the flexural member is 2.67cm,which meets the specification requirements;The maximum bending moment of a cantilever beam is M_max=2.4×10⁶ N·m,and the maximum bending capacity of the cantilever beam plate structure is M_u=2.8×10⁶N·m,under the premise of reinforcement requirements,and M_u=2.8×10⁶N·m>M_max=2.4×10⁶ N·m,it basically meets the requirement of flexural capacity,and The combined grouting reinforcement of the derrick foundation fully meets the requirements.?6?The 1#shaft derrick foundation of the FoLing tunnel is reinforced by the whole,and the engineering monitoring is carried out.Results show:The maximum settlement of the 4 bases has been significantly reduced,at the same time,the maximum uneven settlement has also been obviously controlled,indicating that the scheme has a good effect on the the control of uneven settlement and ensures the safety and stability during the construction period.