The Application of Impact Tester for Compaction Control

摘要

填土品質之優劣方工程之成敗息息相關,冗長的工地密度試驗嚴重影響工程進度.於工期的壓力下施工品質往往達不到要求,以致造成完工後沉陷、承載力降低等無法估計、彌補的災害.如何改善填土工程品質的檢測技術、增加檢測效率,實屬現階段工程界所應努力的目標.近年蔚為流行之非破壞性檢測(Nondestructive Test,NDT)其原理正符合這項功能秘要求.本研究以新竹香山砂土為例,以土壤衝擊試驗錘(soil impact tester)與傳統夯實配對試驗,比較試驗值間的相關性,借比評估土壤衝擊試驗錘檢測方法運用於工地密度試驗之優劣利弊.研究結果顯示衝擊值(impact valre,Ⅳ)與夯實土體之含水量具有顯著的相關性,而衝擊值與含水量的關係曲線與夯實曲線均同屬唯一曲線.依據研究結果,以土壤衝擊試驗於現地檢測所得之衝擊值,配合快速檢測含水量試驗方法,對照圖表可略知乾密度之大小,提升衝擊試驗錘於工地密度檢測之可行性.%The safety of the earth structures is highly dependent upon the fill compaction quality.Recently developed nondestructive testing techniques (NDT) present many advantages in comparison with conventional field density measurements.Therefore,use of NDT in monitoring of the fill quality appears to be attractive for future pavement geotechnics applications.This paper presents an alternative technology using non-destructive Clegg impact tester for compaction control in silty sand.132 compaction tests and impact tests with varying values of compaction effort,moisture content,and density were conducted in laboratory.Each observed impact value (IV) was then considered as a function of its corresponding compaction effort,moisture content and dry density.Results of the study show that for the silty sand tested,the variations of IV with moisture content are similar to the corresponding unique moisture-density compaction relationship.The values of IV generally correlate well with moisture-density relationship for each compaction effort.Along wity a speedy moisture tester,dry density can be predicted using target Ⅳ values in a fast and efficient manner based on current standard specification.