煤矿井下预应力锚索加固

Prestressed Anchor Reinforcement in Underground Mine

泵房和变电所硐室采用预应力锚索加固修复,经2年多观测,围岩变形很小,基本趋于稳定。锚索长6～10m,设计锚固力400kN,用4根7×φ5mm钢绞线做预应力锚索,间距3～3.5m,每组6根,钻孔后,放入钢绞索,灌注砂浆,安装锚具,施加440kN预应力,然后锁紧。

Two spa(?)ings for a pumping room and electric power transmission station in No 2 Underground Mine of Feng Feng Coal Mining Administration were supported with bolting and concrete shoting, H steel or channel type steel supports and reinforced concrete.After 2 years in use,the two spacings was deformed and failare. After study the spacings,two type prestressed anchors with a free arrangement and two side arrang(?)ment were used for the reinforcement of the spacings.The prestressed anchor is consisted with 3 sections.And they are anchoring sectionhead.tension section and out anchoring section.The anchor is 6m to 10m in length and has a designed anchoring forc(?) of 400KN.The pre-stressed anchor was made of 4 steel cables with a diameter of 5mm. The distance between anch(?)rs was 3 to 3.5m. Each group of anchor had 6 cables.Two cables were for roof, two cables for ribs and floor. The operation of anchor is first to drill a hole with a hydro drill.The diameter of a drilling hole was 89mm.when a drilling hole is in a designed depth, the anchor can be prepared according to the depth and length for instalation and than te cut off.The head of anohor was in a big round type in order to have higher anchoring force,After the anchor was placed in a drilling hol(?),cement groutiug was conducted. As the anchor was well set, a tension tool with a 600 XN force was used to tension the anchor with 440 kN forces. After the reinforcement of anohor in two spacings, there is a little deformation in surrounding rocks and the rocks are instable.