<span><span style、" font-family: 宋体;">防止管涌</span></span>
<span><span style、" font-family: 宋体;">防止流砂</span></span>
<span><span style、" font-family: 宋体;">防止塌方</span></span>
<span><span style、" font-family: 宋体;">防止涌水</span></span>
<span><span style、" font-family: 宋体;">减小横向荷载</span></span>