Study On Prediction Method Of Surface Subsidence Caused By Subway Tunnel Construction In Urumqi

With the rapid development of economy in our country,urban population sharp growth,the resulting traffic congestion problem is increasingly serious.The construction of urban subway to a certain extent,relieves the phenomenon of traffic congestion,but also causes a certain degree of damage to the city,restricting the development of the city.Among them,because the subway construction destruction of undisturbed soil caused by construction area of the surface subsidence problem particularly common.In order to reduce the damage caused by the subway construction on the surrounding surface,it is necessary to develop the corresponding monitoring scheme to monitor the land subsidence,and to forecast the settlement trend by using the collected settlement data.The research content of this paper is part of the horizontal topic "urumqi city rail transit line 1 11 blocks of settlement deformation monitoring,based on the settlement monitoring data collected during the construction of the 11 section of Urumqi Metro Line No.1,to analyze in urumqi special pebble geological conditions ground subsidence caused by metro construction.Mainly studying the influence of deep foundation pit excavation on the surrounding ground settlement,emphatically analyzing the variation law of the maximum settlement of 5 large sections in the foundation pit with the displacement changing and the variation of the settlement of single surface points with time.The long time grey prediction model isestablished by the combination of polynomial regression and grey theory,and analyzing the 4 factors which affect the prediction accuracy,such as the length of the sequence,the initial value of the settlement,the number of times and the data types,comparing the forecast values and measure values to verify the feasibility of the prediction model.The studies show that the surface settlement caused by deep foundation pit and tunnel excavation in urumqi special pebble geological conditions is about 2mm-4mm,but the influence area exceeds the layout area of the monitoring points;Foundation pit cross-sectional maximum settlement with the increase of the distance between the surface point and the edgeof the foundation pit,the change trend of maximum settlement decreases firstly,then increases and finally decreases,which shape is similar to a "scoop" form;It is feasible to predict the settlement value of a single surface point by using the combination of polynomial regression and gray theory,and playing a certain reference function for subsequent settlement prediction work of the same geological conditions.