Stability Analysis And Deformation Of Research Of Deep Excavation In Lanzhou

Lanzhou municipal party committee municipal government in 2013 for the comprehensive implementation "the three years effective mitigation, five years significantly improve" smooth traffic target, will smooth traffic project "number one project" as a service people, around the established "a horizontal, three-ring, JiuZong" backbone network system, in the urban core implementation across the wear on 184 project, at the same time the first phase of the subway line 1 and line 2 across the board, mass produced a large number of engineering construction of foundation pit engineering problems. Due to wear under the most engineering is located in the center of the city traffic jam, space narrow, surrounding environment is complex, the foundation pit engineering improper handling can cause safety problem.Based on lanzhou project- day water under the first dealership in readers avenue tunnel excavation engineering as the research background, combining with theoretical analysis and numerical simulation method, Analysis software to carry on the numerical simulation of the actual process of foundation pit excavation using the MIDAS/GTS numerical analysis of foundation pit in the process of excavation supporting horizontal displacement of retaining structure, the ground settlement around foundation pit deformation and uplift deformation regularity of occurrence and development. At the same time, the study analyzed the excavation procedure, the pile depth, pile diameter, pile spacing, steel support spacing displacement of retaining structure, the ground surface settlement, basement uplift deformation rule, paper main research contents and results are as follows:(1)Refer to the current research situation of a large number of literature on the stability of domestic and Lanzhou area and the deformation law of foundation pit engineering are summarized, elaborated the foundation stability calculation, deformation mechanism and deformation calculation theory.(2)The use of integral stability analysis of retaining structure, relying on engineering calculation software of heave resistant stability, anti overturning, anti slip stability checking computations are conducted analysis of a foundation pit stability, analysis results show that the artificial dig hole pile and lateral steel support retaining structure can ensure that the foundation pit during excavation safety and stability.(3) The numerical analysis results show that: for the row piles and lateral steel support foundation pit in foundation pit excavation depth, small, before the erection of steel support, horizontal displacement of supporting structure for the performance of the cantilever displacement; the erection of steel support, horizontal displacement of supporting structure is development of displacement for the parabolic shape. Settlement of surrounding ground surface deformation performance from the wall to the farther settlement, spoon shaped distribution of smaller, from the walls in foundation pit excavation depth is about 0.4-0.7 times the range, the maximum value of ground settlement.(4) The results of the monitoring and comparison of the results of the numerical simulation show that: Consistent with the simulation curve and actual curve variation, and by the influence of construction and precipitation and other factors, measured pile maximum horizontal displacement is 9.6mm, much smaller than the warning value of 30 mm, indicating that this design is on the safe side.(5) Have a certain influence of pile retaining pile depth, pile diameter, pile spacing on the stability of the foundation pit and deformation rule. Change the pile embedded depth has little effect on the settlement of surrounding ground, but the effect on horizontal displacement of the retaining structure is relatively large; in a certain range, increasing the pile diameter can reduce the displacement of the retaining structure effective settlement deformation and surrounding surface, but the effect on the basement uplift deformation is very limited; the increase of pile spacing will increase the horizontal displacement of retaining wall, thus causes the influence range of deformation and deformation of ground settlement around.