| With the advancement of my country's urbanization process,the development of urban underground space is facing an increasingly complex environment.Therefore,the requirements for the control of construction disturbance and deformation are getting higher and higher.The pipe jacking technology has been widely used in various projects due to its short construction period,strong stratum adaptability,and small excavation disturbance.Due to space development requirements,multi-row pipe jacking projects have emerged,and it is urgent to carry out research on multiple rows of pipe jacking under existing structures to ensure the safe and efficient construction of such projects.In this paper,the second-phase drainage project of Haikou Meilan International Airport,with the three-row pipe jacking under the section of Qiongwen Avenue as the engineering background,analyzes the range of the lateral disturbance zone of the three-row pipe jacking;using MIDAS/GTS software to perform a three-dimensional numerical model analysis to obtain The optimal jacking construction sequence with the control of surface settlement as an index was established,and the comparison and analysis with the field monitoring data were carried out to verify the correctness of the simulation results.Finally,the control variable method was used to analyze the different lateral distances between jacking pipes(1.5 D,3D,5D),different generation layer thickness(2cm,5cm,8cm)and different grouting pressure(100k Pa,200 k Pa,300 k Pa,400 k Pa)on the overlying road.The main conclusions are as follows:(1)According to the superimposed disturbance mechanism,the soil disturbance during the pipe jacking construction process was divided,and the stress state in each area was analyzed to determine the range of the soil lateral disturbance zone;when the pipe spacing is close,The post-construction pipe jacking will not only affect the superimposed settlement of the first construction pipe jacking,but also make the final settlement curve axis closer to the first construction pipe jacking.The superimposed settlement formula of three rows of parallel pipe jacking is deduced;(2)The mutual disturbance and superimposed settlement between the pipes caused by different construction jacking sequences are obviously different,but the force of the pipe segments after different constructions is basically the same;the maximum soil settlement is determined by different construction sequences.It is 9.02 mm,10.0mm,10.4mm;comprehensively considering the surface settlement and the force of the segment,it is finally concluded that the optimal construction sequence is to adopt the working condition "two sides first and then the middle" jacking;(3)When the 1# pipe jacking machine arrived at Qiongwen Avenue,the curve fitted by the field monitoring showed the Peck curve law;when the 3# and 2# pipe jacking were jacked,additional settlement occurred in the 1# pipe jacking area;The numerical simulation results show that both sides of the settlement curve are large and the middle is small,and the two are relatively consistent,indicating the correctness of the numerical simulation method and calculation results;(4)Numerical simulation analysis shows that as the pipe spacing increases,the final settlement value gradually decreases,and the shape of the settlement curve changes from "V" to "U" and then into a double "W" shape;when the pipe spacing is less than 3D,the two Between the pipes is a strong disturbance zone,the superimposed settlement is obvious,and the surface settlement value is large,which is not good for safety.As the thickness of the equivalent layer increases,the settlement value gradually decreases;as the grouting material hardens,the superimposed settlement decreases,thereby reducing the final settlement value;in order to better control the surface settlement,grouting should be ensured The area is about two centimeters or more outside the pipe segment,and it should not be too large to prevent the formation of slurry between two adjacent pipes.When the grouting pressure increases,the surface settlement value gradually decreases,and the width of the settlement tank gradually decreases.When the grouting pressure is greater than300 k Pa,a small range of uplift occurs on the surface.(5)In the large-diameter multi-row pipe jacking project that crosses the subgrade,when the pipe spacing is 3D?5D,the grouting pressure is controlled at 200 k Pa?300k Pa,which can better control the surface settlement and be within the economical,safe and reliable range.Figure [60] Table [7] Reference [49]... |
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