Research On Soil Deformation And Control Technology In Pipe Jacking Construction

As a kind of underground excavation construction method,pipe jacking method has been widely used in practical life.Due to the high concealment of such projects,the excavation and support of soil in the construction process will have a complex deformation effect on the environment,which is intuitionally manifested as the settlement and uplift of the surface.Combined with a water diversion project in Suzhou city,using ABAQUS finite element software,the single-row pipe jacking and parallel pipe jacking were numerically simulated to study the impact of different construction factors on soil deformation,and the simulation results were compared with the measured data.The main results include:(1)Summarizing the previous research results,it is concluded that the causes of soil deformation caused by pipe jacking construction include stress disturbance and stratum loss,among which stratum loss is the main reason.The disturbance zone can be divided into four zones: extrusion,shearing,unloading and consolidation.(2)It can be seen from the simulation of the single-shaped pipe jacking that as the depth of the soil increases,the amount of settlement directly above the pipe increases,and it decreases far away from the pipe,the critical point is 2D?2.5D on both sides of the pipe(D is the outer diameter of the pipe);The increase in pipe diameter has a linear relationship with the increase in soil settlement;the increase in thrust surface pressure,the increase in friction coefficient and the decrease in the coefficient of static earth pressure will all cause the increase in soil settlement.The maximum settlement and s are exponential functions;as the hoop porosity increases,the front soil will no longer be uplifted,and the overall axis direction will settle.(3)It can be seen from the parallel pipe jacking simulation that the impact of construction on soil deformation at different depths mainly appears in the range of about6 D on both sides of the pipe.The soil at the center of the two pipes is subjected to double compression,as the depth increases,the settlement curve changes from U to W shape;the soil on the lower side of the pipe jacking changes from an M shape to an inverted U shape;the critical axis distance is about 6D,the settlement decreases and the settlement range increases after 6D;simultaneous jacking has a greater impact than the settlement caused by successive jacking,the soil settlement within 12 m on both sides of the pipeline reaches 80%?90% of the total settlement;under the same crosssectional area,the settlement caused by rectangular pipe jacking construction is 1?2mm more than that of round pipe jacking.(4)Comparing the simulation results with the measured data,it is found that the simulation conforms to the actual soil deformation regularity,which is of reference significance.Based on the causes of soil deformation,several control measures are proposed for reference.