CAJ | 학술논문

土钉支护因其施工简单、造价低、工期短和施工技术成熟等优点，在工程中得到广泛应用，但目前其设计计算理论缺乏，且现行规范给出的变形允许值存在不足，如现行土钉规范（规程）仅是简单地规定一个变形允许值，没有结合基坑的特点、支护类型、周边环境等因素来规定，更没有将基坑的变形与基坑稳定联系起来综合确定其监测指标预警值等，因此，导致这种性价比很好的支护技术有减少应用的趋势。利用变模量强度折减法对土钉支护变形和稳定关系进行了探讨性研究，经大量的计算分析，给出了土钉支护的变形与稳定统一判定指标--位高比?h/H，且计算发现，同一种土质、同一稳定系数K对应的不同高度H的位高比几乎相等。给出了一定强度和一定深度土钉支护位移预警值和最大位移允许值，利用给出的表格，可直接确定其位移预警值和最大位移允许值，便于工程师应用，也为实际土钉支护结构确定变形预警值提供了参考。提出的方法不仅能够确定土钉支护结构变形值，且对类似支护结构确定变形值也提供了一种方法和思路，对推进基坑规范完善和改进具有一定的参考和借鉴作用。
토정지호인기시공간단、조개저、공기단화시공기술성숙등우점，재공정중득도엄범응용，단목전기설계계산이론결핍，차현행규범급출적변형윤허치존재불족，여현행토정규범（규정）부시간단지규정일개변형윤허치，몰유결합기갱적특점、지호류형、주변배경등인소래규정，경몰유장기갱적변형여기갱은정련계기래종합학정기감측지표예경치등，인차，도치저충성개비흔호적지호기술유감소응용적추세。이용변모량강도절감법대토정지호변형화은정관계진행료탐토성연구，경대량적계산분석，급출료토정지호적변형여은정통일판정지표--위고비?h/H，차계산발현，동일충토질、동일은정계수K대응적불동고도H적위고비궤호상등。급출료일정강도화일정심도토정지호위이예경치화최대위이윤허치，이용급출적표격，가직접학정기위이예경치화최대위이윤허치，편우공정사응용，야위실제토정지호결구학정변형예경치제공료삼고。제출적방법불부능구학정토정지호결구변형치，차대유사지호결구학정변형치야제공료일충방법화사로，대추진기갱규범완선화개진구유일정적삼고화차감작용。
Because of the advantages such as easy construction, low cost, short construction period and mature construction techniques, soil nailing has been widely used in engineering. However, at present there is lacks of the calculation theory of soil nailing, and shortages also exist in allowable deformation values specified by current specifications. For example, current soil nailing specifications just simply specify an allowable deformation value without considering features of foundation pit, supporting types and surroundings;and these specifications also determine the early warning value for monitoring without combining the deformation with the stability of foundation pits. Thus, these shortages lead to the downward trend of usage of soil nailing that has good performance-price ratio in fact. Based on this, the variable modulus strength reduction method to investigate the relation between deformation and stability of soil nailing is used. After a large number of computational analyses, the comprehensive identification index-deformation-height ratio ?h/H is given for deformation and stability of soil nailing. It is found from the computational results that for the same soil and the same stability factor k, the deformation-height ratios of different heights H are nearly the same. Also, the early warning displacement and the maximum allowable displacement are proposed for certain strength and depth of soil nailing structure. Using the tables can determine the early warning displacement and the maximum allowable displacement, which is convenient for engineering application. A specific project proves the reasonableness of these results;and these results can also give reference for deformation early warning values of actual soil nailing structure. This paper could not only determine the deformation of soil nailing structure, but also offer a new method and idea to determine deformation of similar supporting structures, which has some significance for improving the specifications of foundation pits.