搅拌水泥土锚杆作用机理及基坑支护工程应用

Mechanism of cement-soil mixing anchor and application in foundation pit support project

介绍了一种适用于软土地区的新型土层锚杆——搅拌水泥土锚杆,该锚杆可利用搅拌叶片对锚固体产生的压力提高锚固体与土体之间的黏结摩阻力,且钻杆及叶片作为加筋体与水泥土固结体共同形成锚固体。在试验场地进行了13根不同直径(250,300,350,400mm)锚杆与2根钢管式土钉抗拔对比试验,其长度均为12m。试验结果表明:搅拌水泥土锚杆的抗拔力特征值是土钉的1.6～1.9倍;在80kN荷载下,250mm锚杆平均位移较土钉小5.01mm,其工作性能明显优于土钉,且锚杆蠕变满足要求。搅拌水泥土锚杆在基坑支护工程应用结果表明:采用搅拌水泥土锚杆可以达到预期加固效果。

Cement-soil mixing anchor which is a new soil anchor and is applicable in the area of soft clay is introduced in this paper.This anchor can improve the friction resistance force of bonding between the anchorage body and soil by utilizing the pressure of mixing blade on the anchorage body.Furthermore,the drill pipe and blade is served as a reinforced body and forms an anchorage body with the cement-soil body.Then,anchor uplift comparative tests are executed between 13 anchors for different parameters(250 mm,300 mm,350 mm and 400 mm) and 2 steel soil-nailing in a length of 12 m.The test results show that the bearing capacity of the anchor is 1.6～1.9 times that of the soil-nailing;the average displacement for the anchor in a diameter of 250mm is 5.01mm less than that for the soil-nailing under the loading of 80 kN;Therefore,the effect of the cement-soil mixing anchor is superior to that of the soil nail in the same condition and the creep is also satisfied with the specification.At last,the cement-soil mixing anchor is applied in the practice of foundation pit support and the test results show that the application of the cement-soil mixing anchor can reach the expected reinforcement effect.