Research On Application Of Groundwater Control And Seepage Law Of Deep Foundation Pit

Under the current general trend of economic globalization,rapid development,and urbanization,the scale of urban infrastructure has undergone earth-shaking changes,the use of above-ground space has been maximized,and the utilization and development of underground space has gradually received attention from all parties.How to achieve the maximum and optimal use of limited land resources is the latest challenge faced by all countries.In the development process of underground space,deep foundation pit engineering is one of the fields with strong technicality and high degree of complexity.There are many technical problems to solve in the survey,design and construction of foundation pit engineering,especially in the development of foundation pits.The groundwater-related engineering problems encountered during the excavation process,so what kind of foundation pit protective devices and precipitation measures are taken to control the groundwater is a vital issue to ensure the safety of the foundation pit construction process.This article takes the deep foundation pit project of No.1,No.2 and No.4 entrances and exits of Beidajie Station of Taiyuan Metro Line 2 as the background,summarizes and summarizes the groundwater control technology methods,and summarizes several forms of groundwater seepage damage.Several forms of groundwater seepage damage that may occur during the excavation and construction of the foundation pit are quicksand,piping,and outburst at the bottom of the foundation pit.The main groundwater control methods used in the actual foundation pit engineering are divided into several measures that use water-proof curtains,dewatering,and the combined use of water-proof curtains and dewatering.This paper calculates the hydrostatic pressure and active earth pressure of the seepage with and without the effect of precipitation,and uses the finite element software MIDAS GTS NX to simulate the precipitation process of the No.4 entrance and exit foundation pit,and draw the following conclusions:(1)The calculated water and soil pressures from the three inlets and outlets are about 20%less than when seepage is not considered.In actual foundation pit engineering,seepage calculation is often not considered,and the calculated water and soil pressure values are conservative.Although engineering safety has been correspondingly guaranteed,the increase in engineering costs has caused unnecessary waste.Therefore,the water and soil pressure considering the seepage effect should be used in the calculation and analysis,so as to make the design more reasonable and reliable.(2)Through numerical simulation,it can be known that in the construction of foundation pits,the water-stop curtain has a significant water-stop effect;the combination of water-stop curtain and pit precipitation can ensure the waterless operation of the foundation pit,thereby ensuring the construction of the foundation pit In the case of precipitation,the hydraulic gradient shows a decreasing trend along the retaining structure from top to bottom,but the magnitude of the change is not large;as the excavation depth of the foundation pit increases,the soil side of the sidewall of the retaining structure The pressure is getting bigger and bigger,and the corresponding supporting axial force is getting bigger and bigger.Dewatering in the pit and reasonable setting of supports(upper concrete support + lower steel support)can well control the deformation and surface settlement of the foundation pit.