软岩复合支护结构

Composite support structure for soft and weak rock

沈北煤田从1958年开发以来,有3个生产矿井和1个在建矿井。全矿区岩石松软破碎,支护困难。六十年代初,研究支护结构,采用花岗岩料石圆(石旋),有一定效果,但仍经常发生(石旋)体压坏,需经常维修。以后改进了巷道布置,减少了采场动压的影响。巷道破坏有所好转,但仍未根本解决问题。大桥立井位于沈北煤田西部,井筒掘进中随掘随片帮,岩石见风遇水,风化崩解。

the rock strata in Daqiao Mine, Shengbei Administration are easy to be weathered and hydrolyzed, and have a low strength and high swelling Power. Tests of repeated support were made in the middle return roadway: the initial support was rock-bolting with wire mesh and shotcreting which released 50% of the stress (the secondary support was pre-fabrioated reinforced concrete segments which released 15% of the stress, if the load bearing capacity of the segments was 30%. For initial support, the bolt body is 12mm in dia, 1.2m long, spacing 0.5m. The wire mesh is made of 4mm dia. wire, 0.1×0.1m, which is fixed on bolts with end plates. A layer of 100mm concrete is sprayed on the wire-mesh. segments with double layer of reinforcements are used, the concrete strength being 300. The segments are 200mm thick, inner diameter 3m. The snpport consists of 5 segments, namely 3 large blocks of 2.3m long, 2 small blocks l.57m long, 0.4m wide. At the junctions of segments 200mm wood pads are used, and segments are installed by a simple erector. Tests indicate the secondary support has less deformation and less internal force; it is safe and the length of the bolts can be increased and thickness of segments can be reduced.