The Research Of Waterproof Curtain Reinforcing Soil Nailing Wall

In the current specification and engineering design,the waterproof curtain is generally regarded as a safety reserve without considering its retaining effect,tend to make the foundation pit support design conservative,easily lead to engineering waste and is not conducive to promote soil nailing wall supporting technology.Thererfore,it is necessary to study the effect of waterproof curtain on the working performance of soil nailing wall.In this paper,based on theory of cement-soil pile waterproof curtain + soil nailing,a form of composite soil nailing wall support,by using finite difference software FLAC 3D based on M-C constitutive model,the strength subtraction and the theory of the traditional limit equilibrium method,etc.and Combined with a foundation pit project case in accordance with the specific construction conditions established to consider the waterproof curtain and do not consider the waterproof curtain of the two calculation models.Through the comparison of the calculation results,the degree of enhancement of the waterproof curtain to the soil nailing wall is quantitatively analyzed.In order to verify the reliability of numerical simulation,but also with the actual site monitoring data were compared.In the paper,the quantitative index of the reinforcement of the soil-fixing wall is summarized from the three aspects of the overall stability,deformation and the axial force of the soil nailing wall.(1)The waterproof curtain increases the range of the plastic zone,and the increase of the plastic zone in the passive soil area is the most obvious,which shows that the range of the passive soil is expanding.The waterproof curtain also effectively blocks the penetration of the plastic zone of the slope,bypassing the bottom of the waterproof curtain outward expansion,the corresponding sliding surface range outward expansion is more obvious;consider the water curtain wall nail wall support the safety factor can be increased by up to 30%.(2)The stop curtain reduces the settlement of the slope of the soil nailing wall by44%.The larger settlement area moves in the direction away from the foundation pit,and the maximum settlement point is far away from the depth of 1.42 times the foundation pit.The waterproof curtain reduces the horizontal displacement of 49.6%of the slope of the soil nailing wall,the range of the horizontal displacement is alsonarrowed,and the area of the passive earth pressure area is expanded.The vertical displacement and horizontal The displacement is gradually increasing and the overall variation is relatively uniform,the displacement trend is basically the same,indicating that the waterproof curtain to a certain extent,effectively inhibit the deformation of soil nailing wall.(3)Considering the effect of the waterproof curtain,the maximum reduction of the axial force is 71.9%,which is the most obvious decrease in the middle and lower part of the soil nailing wall.The results show that waterproof curtain has obvious effect on reinforcing soil nailing wall.Considering its function can be further optimized design of foundation pit,reduce the engineering cost,and improve the cost performance of soil nail wall supporting.so that the foundation pit design will be more fit engineering practice,and soil nailing wall technology will be more widely applied.