本文以混凝土牆現地試驗探討鑽心試體直徑對強度試驗值之影響，工程上 常以鑽心試驗檢測混凝土構件完工後之混凝土品質強度。但是鑽心試體之鑽心 尺寸常受到客觀因素影響，未能達到規範之規定尺寸，混凝土抗壓強度試驗之 結果因為受到試體尺寸之影響而不同，鋼筋混凝土構造物鑽心試驗之結果亦因 為試體尺寸之影響而有所差異。本文於現地製作混凝土牆，在未遮蔽環境下暴 露於自然環境中，經過一年期間，分別鑽心取樣直徑為5.0 cm、7.5 cm、10.0 cm 及15.0 cm 四種尺寸、長徑比為2 之混凝土鑽心試體，進行抗壓強度試驗及結 果分析，將結果提供作為工程上評斷及審查混凝土結構物強度之參考。

The present paper investigates the influence of dimensions of drilled cores on their compressive strength through testing. In practical engineering, compression tests of drilled cores taken from completed RC structures are usually conducted to investigate the real concrete strength and quality. However, because of on-site limitations, the dimensions of the drilled cores may not really satisfy code requirements. In this paper experimental studies are performed to investigate the influence of dimensions of drilled cores on the compressive strength. Two concrete retaining walls were placed on-site. After one year, the cores were drilled and test. The diameters of the cores are 5.0 cm, 7.5 cm, 10.0 cm and 15.0 cm with L/D ratio equaling 2. Based on the on-site test results, the proper dimensions for the on-site drilled cores are suggested for practical engineering.