土层锚索浆体与筋体黏结强度的试验研究

国内外对锚杆筋体与浆体黏结强度的研究成果极少。3项工程64个土层锚索现场试验成果表明:(1)各锚筋与浆体极限黏结力的离散程度很大,普遍存着孤低现象,据此反算得到的浆筋黏结强度的离散程度很大,离散程度与黏结长度无关,与锚筋数量及张拉工艺相关;(2)浆筋黏结强度与地层、注浆工艺及锚筋数量无关,带套管成孔、改善孔内清洁程度可明显提高;(3)浆体设计强度与浆筋黏结强度的对应关系无法验证,实际强度及锚筋外形对浆筋黏结强度的影响亦无法验证;(4)浆筋黏结强度的发挥程度随着黏结长度的增加而有所下降;(5)黏结长度3~6 m时,浆筋黏结强度标准值为0.744~0.664 MPa;(6)土层锚索黏结长度不宜短于8 m;(7)单根锚索钢绞线数量不宜为2条。

Tests on bond strength between grout and tendon of soil anchors

The research results about the bond strength between anchor tendon and grout are few. The test results of 64 soil anchors in 3 projects show that: (1) The dispersion degree of the ultimate bond capacity between grout and tendon is tremendous, and its solitary-low phenomenon is widespread. The dispersion degree has nothing to do with the bond length and is related with the quantity of tendons and tension technique, so that of the calculated bond strength of grout-tendon is tremendous. (2) The bond strength of grout-tendon is not related with the in-situ conditions, grout techniques and quantity of tendons, but is able to be improved when drilling with casing pipes and improving the cleanliness of the hole. (3) The relationship between the grout-tendon bond strength and the grout design strength cannot be verified, neither is the effect of actual strength of grout and tendon sharp on the bond strength of grout-tendon. (4) The exerting degree of bond strength slightly decreases with the increase of bond length. (5) The characteristic values of bond strength of grout-tendon are 0.744~0.664 MPa under the bond length of 3~6 m. (6) The bond length of soil anchors should be more than 8 m. (7) The number of tendons in the single anchor should not be 2.