| Rainfall infiltration is the main reason for inducing foundation excavation slope accidents,especially long-term rainfall in the rainy season is more likely to induce foundation pit collapse,and for foundation excavation slopes,most of them have supporting structures and drainage measures.Even so,rainfall leads to Accidents have occurred from time to time.On the one hand,rainfall infiltration will increase the soil pressure of the slope soil,resulting in an increase in the sliding force of the slope;on the other hand,rain infiltration will increase the soil moisture content,reduce the matrix suction,and reduce the strength of the soil.The foundation excavation supported by soil nailing wall technology has a concrete spray layer on the slope surface and a certain length of hardening on the slope top.These can reduce the amount of rainwater infiltration into the soil body.The length of hardening is specified.The current research also rarely involves the length of the slope top hardening,but the slope surface hardening and the length of the slope top hardening have a great influence on the stability of the foundation pit under rainfall conditions.Construction has a good guiding role.In the theoretical study of unsaturated soil,the soil-water characteristic curve cannot be bypassed.The determination of the soil-water characteristic curve is time-consuming and laborious,which brings many inconveniences to practical application,especially in engineering,the measurement period is long and the tester The operation also has certain requirements,so that the application of unsaturated soil research results in engineering practice is hindered,so in conjunction with routine laboratory tests,this paper uses Geo Studio software to simulate the soil-water characteristic curve of the foundation excavation soil,which saves time and The cost can also facilitate engineering applications.The method used in this study has the characteristics of being easy to apply in actual engineering.It not only solves the problem of the hardening length of a specific foundation pit under rainfall conditions,but also has a certain reference significance for establishing a dynamic monitoring system for foundation excavation.This article first introduces the domestic and international research status of slopestability under rainfall conditions,and introduces the purpose andsignificance of the res-earch.Secondly,the theory and method of the analysis of unsaturated soil foundationpit during rainfall infiltration are summarized and discussed.The rainfall simulation is obta-ined by Geo Studio SEEP/W module,and the distribution characteristics of the water pressure and volume moisture of the slope after the rain are obtained.Then,the rain simulation results are imported into the SLOPE/W module.The shear strength parametersobtained by the consolidated quick shear test are used in numerically calculation,and the stability of the excavations is evaluated.The results show that the depth of infiltratetion of instantaneous heavy rainfall is small,and the infiltration depth of ordinary rainfall is large in long periods.The hardened slope top is beneficial to limit the infilt-rateon of rainwater,reduce the infiltration at the slip surface,and is beneficial to the stability of the excavations.When the slope top hardening length is 3 m,the effect of rainfall on the stability of the excavation is not obvious,and when the length is 5 m,the stability of the excavation is basically not affected by rainfall.When the initial wa-ter content of the soil of the slope is low,instead of arousing adverse effect on the stability of the excavations,the early rainfall is beneficial to the stability of the excav-ations.Finally,taking the actual landslide as examples,the simulation results are verifiedand the importance of slope top hardening to the stability of the slope is explained. |
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