Analysis Of Influence On The Surrounding Environment Near Excavation In Ming Guang Road Station

With the development of economy and the increase of urban population,appeared frequently traffic jam,subway construction has gradually become an effective way to relieve traffic. However,The subway station foundation pit has generally situated in the midst of complex environment of the city,close to the metro adjacent buildings, underground pipelines,roads,and buildings,which has narrow construction site and the harsh construction environment. Based on the foundation pit of Hefei Metro Line 1 Ming-guang road station,envelope structure deformation,surface settlement and deformation of settlement building has been studied in the excavation process through on-site monitoring analysis and finite element software MIDAs /GTS simulation calculation. The main work and achievements are as follows:(1) Deformation mechanism of soil in foundation pit excavation,Several surface settlement common patterns and four ground deformations on buildings have been expounded. Envelope structure lateral displacement and settlement of soil behind the wall are the main factor affecting the deformation adjacent buildings;The surface settlement model is mainly divided into triangles and groove-shaped; uneven settlement and horizontal displacement in four ground deformation has big impact on structures.(2) The envelope structure diaphragm wall deformation and surrounding ground settlement law,and adjacent building subsidence change law over with time have been studied. Continuous wall lateral horizontal displacement has evenly distributed in the initial excavation with the excavation face down. its maximum displacement position along the side down,then stabilized at negative ten meters,gradually reduce after,the final deformation curve "belly" bow shaped. Since the excavation plane are also can produce displacement of retaining structures,prevent kicking damage to even the wall bottom,to ensure even the wall must be embedded in the soil depth.(3)With the increasing depth of the excavation,settlement variation caused by excavation pit gradually reduces,finally tends to be stable,and the overall change shape is similar to spoon-shaped. The maximum ground surface settlement is in foundation pit edge eight meters to ten meters location, within 0.4 ~ 0.7 times the depth of foundation pit,and the maximum settlement is 11.51 mm,not exceed monitoring control values in a safe range.Therefore,take protective measures for construction equipments at the edge of foundation pit eight to ten meters to prevent the loss by the surface settlement too large.(4) The excavation impact on Hefei hotel building settlement can be divided into uniform settlement,the influence of differential settlement and stability of subsidence three stages. The greater the distance nearer the edge point subsidence of foundation pit,the greater the distance the farther foundation pit edge measuring point of the settlement value is smaller,but the settlement and differential settlement of the monitoring of the monitoring is in the allowable range,and the impact on the building is not large. Due to the differential settlement is greater than the absolute settlement influence on buildings,the construction should be focused on.(5) The software simulation results show that the lateral displacement curve of diaphragm walling "bow belly" ultimate state,the maximum at negative ten meters; the lateral deformation of the wall has obvious effect of three-dimensional space,and the central part of the wall deformation is bigger than at the ends of the wall deformation. The surface settlement with the increase of excavation depth,deformation outside the pit is similar under the condition,which is similar to the spoon shape. In foundation pit edge less than one time the excavation depth( 22 meters),the surface subsidence is bigger,more than 2 times(40 meters),settlement decreased gradually tends to be stable in the end. These show that model,parameter selection and calculation method is more reasonable. Therefore,immediately next to the building envelope and surface subsidence,pay attention to the monitoring during construction.(6) By comparison with the measured and calculated values show that the wall horizontal displacement,ground surface settlement is broadly in line with a measured and simulated values change trend. But analog value is larger than measured partial,it is because of not fully considered deformation of time-space effect in the process of simulating soil excavation of foundation pit. Because the building load additional role,there are buildings on one side of the wall horizontal displacement measured values and calculated value is much greater than no building next to a bit poor,and they are more obvious differences with the increase of depth even the wall. Comparing with the surface subsidence peck formula,simulated values and measured values,the influence scope of software simulation and peck curve to predict is nearly the same,and their trend broadly consist with the measured value,which verifies that the software parameters selection is reasonable again.