The Analysis And Countermeasures On The Impact Of Stability Of The Cut-off Wall Slot Owing To The Brine Underground

This paper has studied the technical problems of the severe collapse of slots in coastalbrine erosion and the construction of sandy loam soil stratum diaphragm wall, analyzed themajor factors which affect the stability of slots by taking the Shuangwangcheng Reservoir’sconstruction of concrete diaphragm wall in the East-Route of South-to-North Water TransferProject for example, as well as carried out systematic theoretical and experimental researchfrom preparing the ratio of brine mud and conducting field test by adopting dewateringmethod to enhance the stability of slots.While preparing the ratio of brine mud, this paper has selected specific proportion, waterloss, pH and viscosity as major indexes for evaluating the mud property, carried out contrasttest of performance differences between brine mud and fresh mud under the same formulacondition, as well as adopted orthogonal experimental method to study the effect of pulpingmaterials including bentonite, CMC and NaOH on the property of brine mud.The experiment is concluded as follows: compared with fresh mud, the proportion andwater loss of brine mud are relatively high, while the pH and viscosity are relatively low.Bentonite and CMC can enhance the viscosity and proportion of brine mud and reduce thewater loss; while NaOH can enhance the pH, proportion and viscosity of brine mud. Theoptimum proportion of the components of brine dado mud is: bentonite: CMC: NaOH=1000:150:0.5:2.The groundwater level can affect the stability of slot wall. By lowering the groundwaterlevel around the slot, the pressure differences between the internal and external diaphragmwall slot can be formed, which can strengthen the stability of slot. Based on the principle, thepaper has proposed to reduce the groundwater level around the slot to enhance the stability ofslots by adopting the light well point precipitation method. First of all, we’ve carried out thestatic equilibrium analysis on both sides of the slot wall at different depths in variousgroundwater drawdowns, selected the sections where sandy loam soil stratum slot in the brinearea is severely dilapidated, and then carried out field test by adopting light well pointprecipitation method to enhance the stability of diaphragm wall slot. The test shows that theeffect turns out to be obvious when the groundwater level is reduced by around3.5m. At last, we’ve put forward comprehensive technical measures to deal with the collapse ofslots in coastal brine erosion and the construction of sandy loam soil stratum diaphragm wall.For example, lift the slot mud surface to reduce the slot collapse, and reduce the influence ofroad vibration on side stability of slots. Comprehensive measures such as stabilized slotsthrough ratio of brine mud and precipitation method can be applied to the construction ofShuangwangcheng Reservoir’s diaphragm wall in order to minimize the collapse of slot indiaphragm wall and reduce the filling coefficient of the pouring of concrete in diaphragm wall.The research result can be taken as the reference for the construction of diaphragm wall insimilar regions.