| Foundation pit dewatering is a special way to draw water from water resources.It does not take water as the purpose,but to ensure the safety of foundation pit during construction.Therefore,at present,most foundation pit dewatering is conservative,with a large number of construction Wells and a large amount of water output from a single well.However,these water resources are not properly utilized,but directly treated to the urban rain water circulation treatment network,which makes these water resources extremely wasteful.This paper is a reference to the current related theory analysis,and focused on the project of wuhan(center)involved in the analysis of the foundation pit precipitation as the goal,the application of Visual Modflow software related modules to create relevant numerical model of groundwater flow,based on the foundation pit precipitation and the objective function method,model based on MATLAB,the optimization scheme of precipitation,with day han software for settlement calculation,analysis of the precipitation whether adverse effects on the surrounding,and water resources protection measures are put forward.The main research results are as follows:(1)through the Visual Modflow model calculation compared with the measured water level,water level from the model validation results show that the simulation of the generalized is reasonable,by adjusting the model parameters,the model calculated water level and the measured water level is relatively close,the correlation coefficient between the two can reach 0.960,shows that the established hydrogeological conceptual model and mathematical model can correctly reflect the regional hydrogeology and groundwater movement regularity.The water level at 5 days,10 days,15 days,20 days,25 days,and 30 days was predicted respectively.The calculation showed that the trend of water level decline was very fast at the beginning,then gradually slowed down,and after 30 days,the water level gradually stabilized at 8.6m,indicating that the project's bottom stopping curtain had a good effect and effectively cut off the hydraulic connection between inside and outside the foundation pit.(2)The application of a "programming solution" related module in MATLAB software can optimize the design scheme related to dewatering,especially the design of deep foundation pit engineering.Through optimization analysis,the total amount of pit gusher water in the new scheme is 7.1% lower than that in the original dewatering design scheme.In particular,the water level depth at the control point is reduced by 6% compared with that before and after optimization,and reaches the design standard of S0= 11.1m.The optimized scheme can not only meet the standard of water level drop at the control point,but also greatly reduce the damage to the ecological environment,and at the same time reduce the total water inpouring of foundation pit dewatering,which is practical and economical.(3)In order to reflect the spatial law of soil settlement in and around the foundation pit,tianhan software was used to calculate the settlement.Consider the most unfavorable precipitation sedimentation effect: a design with 15 precipitation Wells in the studied area,according to the situation when all open calculation,get the foundation pit near the edge of the ground subsidence in largest for 42 to 45 mm,around 100 m near the maximum subsidence value is less than 2 mm,the optimized design scheme of foundation pit near the edge of the ground subsidence in largest for 40?45 mm,less settlement.Therefore,the theoretical analysis shows that the influence of project precipitation on settlement tilt of surrounding buildings and roads is within the safe range.According to the monitoring report of the foundation pit in December 2018,the maximum settlement value of the foundation pit supporting structure is-2.32mm,the deformation rate is0.07mm/d,the maximum settlement value of the surrounding surface is-3.13mm,and the deformation rate is-0.34mm/d.The settlement of all measuring points is generally small,indicating that the foundation pit enclosure structure is in a stable state.The research results of this paper can not only effectively guide the foundation pit dewatering construction of Wuhan Central Shucheng Project,but also ensure the safety of foundation pit,reduce foundation pit precipitation and surrounding ground settlement as much as possible,and effectively protect groundwater resources.It can also provide reference for the groundwater control scheme optimization and foundation pit dewatering risk prediction of south Feng-water city represented by Wuhan city. |
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