【導(dǎo)讀】濟合理、實用可行是當前現(xiàn)代化城市建設(shè)中一個非常重要和迫切的問題。全國工程建設(shè)突飛猛進，高層建筑如雨后春筍般迅速發(fā)展。應(yīng)予以高度重視因此,但與國外相比，迄今對土釘技術(shù)還缺乏深入系統(tǒng)的研究，因而對土釘支。護作一些研究具有一定的現(xiàn)實意義。本文通過理論聯(lián)系實際的方法，研究了土釘支護的理論計算和實際施工。其他支護形式來說，土釘支護是具有較多優(yōu)點的新型基坑支護方法。析，調(diào)整各項參數(shù)，優(yōu)化設(shè)計方案，使其達到最優(yōu)組合。

　　

【正文】 ld of mainly has: 1 the foundation underpinning 2 the foundation pit retaining or shaft 3 the retaining wall slope 4 the slope stability 5 and bolt for the protection of the retaining wall with cant Drilling grouting soil nailing wall type of excavation way down step by step, every step for 1 ~ 2 meters high, in construction soil nail bar, concrete road surface spray, during the period of slope in the state without support needs to be able to keep independent stable, so is mainly applied in: 1 have certain of the bonding miscellaneous fill earth, cohesive soil, powder soil, loess and weakly cemented of soil slope. 2 application to underground water level below the excavation layer or after rainfall make underground water level elevation below the excavation. 3 for standard peration and several N of soil slope under 10 strike by soil nail method usually don39。t economy. 4 for the new Ip 20 of the index of soil, must pay attention to carefully evaluate the creep characteristics rear can use. 5 for water cut rich silty sand layer, sandy pebble soil nailing layer is no good method. 6 does not apply to no temporary stability ability of silt from the soil and the new state of soft clay flow into the hole hole maintain the stability of the wall is difficult and interface friction is low, technology economic efficiency is not ideal, so also should not be used. 7 soil nail not appropriate for corrosive soil such as coal cinder, coal ash and slag, acidic waste products from mineral soil for permanent retaining structures. THE BASIC PRINCIPLE OF THE SOIL NAILED WALL The soil nailed wall of the mechanism The shearing strength of soil is low, tensile strength almost negligible, but the soil has a certain structure integrity, in foundation pit excavation, can put the slope of the critical height of remain upright, but in more than the depth or ground overload will happen when the whole sudden destruction. General slope protection measures are based on retaining of slope protection passive restriction mechanism, to retaining structure under the soil after the lateral pressure, prevent soil whole stability of the damage. The soil nailed wall technology is placed in the soil body length and distribution density of soil nail and soil body work together, make up for their own strength of the shortings of the soil. So through in order to enhance the stability of slope soil their active restriction mechanism on the basis of the posite soil. Not only to improve the effect of soil overall rigidity, to make up for the tensile, soil shear strength low weakness. Through the interaction, the soil structure strength their potential into full play, a change to the slope deformation and destruction of traits, remarkably raised the overall stability, more important is the soil nailed wall by the load process won39。t happen grain soil slope that sudden collapse slippery, the soil nailed wall not only delay plastic deformation stage of development, but also has the obvious incremental deformation and cracking destruction, won39。t produce integrity collapse slippery. The mechanism of the soil nail Soil nail in the role of posite soil body have the following: 1 of posite soil nailing soil skeleton of the hoop role the posite soil deformation and restricting soil make a whole. 2 of soil nail and soil to take the soil and the load gravity stress, soil nail share the role, because soil nail has very high tensile shear strength, so the soil into plastic condition, stress gradually to transfer of soil nailing, soil nail share the role is more outstanding. 3 soil nail the stress transfer and diffusion delayed the formation and development of crack area. 4 the constraints of the slope deformation role in slope surface of soil nail and set in the steel spray TongMianBan limit with slope excavation unloading and inflation deformation, strengthen the function of the boundary constraints. The design principles and the matters needing attention The soil nailed wall structure used to subentry coefficient of said limit state to carry on the design. Foundation pit supporting structure limit state is divided into the following two kinds: one kind is the bearing capacity of limit state corresponding to the supporting structure to achieve imum carrying capacity or soil instability, too large deformation, resulting in foundation pit supporting structure or surrounding environmental damage. Another kind is the normal use limit state, corresponding to the supporting structure deformation already hinder underground structure construction or affect the normal use of the foundation pit surrounding environment function. The soil nailed wall design calculation to consider foundation pit wall security level we adopt different importance coefficient r. the soil nailed wall as the foundation pit supporting structure form should carry on the carrying capacity of the calculation of the limit state, including tensile bearing capacity of soil nailing the soil nailed wall overall stability checking。 Single soil nail at the garden arc sliding surface crack the solid and the limit of the soil anchor railroad cars/containers puting。 CongLve calculation formula. excavation scheme, and soil nailing wall scheme to fully familiar with the prior to the perimeter of the foundation pit and environment conditions. Such as the foundation pit excavation influence within the scope of the original buildings, structures, road, underground facilities, all kinds of underground pipeline, light is in geotechnical engineering and underground water as well as the edge of the slump, the soil deformation dangers to have full estimation, and necessary protection measures. Usually on the surrounding drainage, cut water, reduce the ground wat