Application Of Soil Nailing Technology In Sand Foundation Pit

With the development of China's economic development,the process of urbanization is accelerating.At the same time,Foundation pit engineering is also in constant development.There are many kinds of research on the supporting method,and all kinds of supporting methods have been put forward.Among them,the technology of soil nailing is favored by engineers because of its simplicity,convenience and economy.However,soil nailing technology has its own limitations,which is usually used in the soil with good self reliance.For the sand foundation pit,the use of soil nailing is less.Because of the poor stability of sand.Dry sand or saturated sand is generally considered to have no cohesion.But non saturated sand tend to have a "quasi cohesion".For this,in the design,it can be considered an appropriate.This can greatly save the engineering budget.At the same time,it can also bring great convenience to the construction.In this paper,the feasibility of using soil nail support technology is analyzed.First,the natural repose angle of sand is discussed in this paper.Then,the stability of sand slope is analyzed theoretically.Based on the cohesion of unsaturated soil,the stability of the slope will be improved after adding the soil nail.The lateral friction resistance of soil nailing is also helpful to improve the stability of sandy slope.The shear strength characteristics of unsaturated sand are discussed by three axis shear test.The experimental results showed that the stress-strain curve of sand and the Mohr envelope.According to the Mohr Kulun criterion,It is concluded that the sample has a certain cohesion.Through research and analysis: The pseudo cohesive strength of unsaturated sand is affected by water content and clay content.In a certain range of water content.The quasi cohesive strength firstly increased and then decreased.When soil nailing technology is used in sand foundation pit.First of all,the stability of soil nailed hole wall in sandy soil must be guaranteed.The stability of the hole wall is mainly affected by the cohesive force of sand by the Mohr Kulun criterion.There is a limit of cohesion value C '.When the soil cohesion value is larger than the limit value.Drilling can be done smoothly.When it is less than the limit value.Drilling can not be done smoothly.In sand foundation pit.If pseudo cohesion is large enough,the soil nail hole can be made smoothly.Based on actual condition.Soil nailing can be considered in the foundation pit.The calculation of the soil nailing supported by the foundation pit of the Energy Finance Mansion in Xi Xian new district was carried out.The stability coefficients can meet the requirements.And compare the monitoring data during construction.It shows that the soil nailing technique is feasible in the sand foundation pit.At last,Using Midas/GTS software on the stability of foundation pit.The results showed that the stability of the foundation pit can meet the requirements.