超前錨桿施工方案.doc

超 前 錨 桿

松散地層結構松散，穩定性差，若有地下水時則更甚。在施工中極易發生坍塌，在這類地層中施工時，除減少對圍巖的擾動外，還應加強臨時支護，臨時支護可采用超前錨桿。
1． 施工方法
超前錨桿又分為懸吊式超前錨桿及格柵拱支撐超前錨桿。
1.1懸吊式超前錨桿
采用這種方法是在baopo前，將超前錨桿打入掘進前方穩定巖層內，末端支承在拱部圍巖內專為超前錨桿提供支點的徑向懸吊錨桿，或支承在作為支護的結構錨桿上，使其起到支護掘進進尺范圍內拱部上方，有效地約束圍巖在baopo后的一定時間內不發生松弛坍塌，為大斷面開挖與噴錨支護創造了條件。施工中，因超前錨桿與懸吊錨桿的外露端往往不易直接相交，故以φ22的橫向短鋼筋焊在鄰近的懸吊錨桿上，再焊在超前錨桿的末端上。
1.2格柵拱支撐超前錨桿
如圖所示：超前錨桿的末端支撐在格柵拱架上。
Chaoqianmaogan

Loose loose formation, stability is poor, if it is even worse when groundwater. Easily occur in the construction collapsed in the construction of these strata, in addition to reducing the disturbance of surrounding rock, it should also strengthen the temporary support, temporary support can be used ahead of Bolt.
1. Construction Method
Lead anchor is divided into grid suspended ahead of arch support bolt and bolt ahead.
1.1 suspended ahead of Bolt
This approach is in the blast, before driving into the front will advance stability and rock bolts, the end of the supporting rock within the arch to provide the fulcrum for advanced radial suspension bolt anchor, or as a support for supporting structural bolt on to play a range of support driving rate above the arch, the effective constraint rock blasting within a certain period of time after the collapse relaxation does not occur for the large section excavation and shotcrete support created the conditions. Construction, due to advanced suspension bolt anchor and often difficult to directly intersect the exposed side, so as to φ22 short horizontal sealing the adjacent bolt on suspension, and then welding the end of the bolt in advance.
1.2 grid ahead of arch support bolt
Shown: the end of support ahead of bolts on the steel grid.
 

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