Study On Supporting Structure For Excavation Of Hardening Furnace Foundation In China Secondheavy Industries

Earth pressure acting on the retaining structure is reduced greatly comparing to the middle position of straight side, because there is soil arching effect around the circular foundation pit; main stress of the retaining structure is pressure under circular retaining structure, and there is nearly no tensible pressure so the high pressure property of the concrete can work fully, as a result, more and more circular retaining structure appear. In this paper, take the quenching furnace foundation engineering of the China Secondary Heavy Machinery Group as an example, study the space effect, the supporting scheme and the internal force of the retaining structure and so an. Main research contents and results are as follows:(1) Argue on various retaining structures which can be applied to circular foundation pit, it shows that the retaining structure of piles in row+internal bracing+concrete padding between piles+sealing works of Jet Grouting Piles is dependable, economical, operable and reasonable, and it is the best retaining structure to this foundation pit.(2) Comparing with the linear retaining structure, space effect is prominent in the circular retaining structure, and the main internal force of the retaining structure is pressure under the same earth pressure; because earth pressure increase with depth rising, the inaccuracy is larger depending on plane problem. In this paper, propose a mechanics model that thick-walled cylinder bearing linear soil pressure and inner supporting, and obtain stress and displacement solution. The result shows that the internal force and the deformation of supporting structure are both smaller and closer to the measured value.(3) Build a finite-difference model to simulate the foundation pit excavating, and study the stress field changes and deformation of the retaining structure and the environment. The result shows that deformation of the retaining structure is smaller, and the largest deformation is only about 22mm; influence causing by foundation pit excavation is also smaller, and the largest settlement is only 7mm, it shows that this retaining structure is reasonable and dependable.(4) According to actual situation, establish a monitoring scheme for foundation pit excavation to monitor earth pressure, internal force of retaining structure and so on, so the retaining structure safety and surrounding environment changes can be known in time. The monitoring data analysis shows the value of earth pressure change continuous and changes are smaller, so it is indicated that the influence of foundation pit excavation is controlled in a rational range.(5) Compare the theoretical, numerical simulation and monitoring results. The results show that earth pressure present distribution of "middle larger, sides smaller", and the largest earth pressure appear at depth range that 18m to 23m. The earth pressure value of numerical simulation is the largest, followed by theoretical value and the monitoring value is the least, the reason leading to this difference is that theoretical calculation and the numerical analysis are both simplified, meanwhile, data position are different a little. The results in three methods are controlled in 0.9MPa so that the results are consistent in some degree, it shows that this retaining structure is reasonable and reliable, and it can prove some experience to the similar project.