基于玻璃纤维锚杆微应变测试的软岩隧道松动圈测试技术及应用

A Loose Circle Test Technique Suitable for Weak Rock Tunnels Based on Glass Fiber Anchor Micro-Strain Test and Its Application

为解决软弱破碎围岩地层隧道松动圈测试的难题,分析现有松动圈测试技术现状,以全长黏结型玻纤锚杆为载体,提出一种适用于破碎软岩隧道的围岩松动圈测试技术。该测试技术以锚杆微应变变化趋势为基础,结合锚杆中性点理论,可大致确定围岩松动圈范围。将该技术应用在大(理)临(沧)铁路杏子山隧道破碎炭质板岩大变形地段进行验证,结果表明:全长黏结型玻璃纤维锚杆在松动区可与软弱破碎围岩有效协调变形,锚杆微应变变化趋势与中性点理论相符,采用锚杆微应变变化趋势表征围岩松动圈范围合理可行。同时该技术测试精度可通过调整沿锚杆长度粘贴应变片的密度来控制,有效弥补传统物探松动圈测试技术对岩体要求高的问题,在软弱破碎围岩地层中具有较好的操作性和适用性。

In order to solve the technical problem of loose circle test in fractured soft stratum, a loose circle test technique for fractured soft rock tunnel with full-length bonded glass fiber anchor as carrier is proposed. The test technology is based on the variation trend of the micro-strain of the anchor, which can analyze the range of the surrounding rock loose circle according to the neutral point theory of the anchor. The measurement technology has been tested in the large deformation section of carbonaceous slate in Xingzishan Tunnel on Dali-Lincang Railway. The applicable results show that the full-length bonded glass fiber anchor can effectively coordinate the deformation with the fractured soft surrounding rock in loose zone;the strain of the anchor is sensitive in different area of the surrounding rock and it can characterize the range of loose circle significantly. At the same time, the technical test accuracy can be compensated by the density of the strain gauge attached along the length of the bolt. The technology effectively compensates for the problem that the traditional loose-circle geophysical testing technology has high requirements on rock mass, which has good operability and applicability in the fractured soft surrounding rock stratum.