A.≥6倍樁徑 B.≥4倍樁徑 C.≥8倍樁徑 D.≥2倍樁徑
A.N/μ〔P〕 B.μN/〔P〕+1 C.N/μ〔P〕+1 D.μN/〔P〕
A.16~20cm B.18~22mm C.20~24mm D.16~24mm