Supporting of soft rock tunnel excavation has been one of the key technical problems which affects the further development of coal industry production and construction of our country . Deep mine ground pressure intensity is high, under the condition of mining influence and impact ground pressure and strata control is especially difficult, thus support system is more and more strengthened, such as the need to reduce the frame from u-shape set, strengthen the link rod, and even to use U36 steel;spray the anchor net supporting to reinforced by steel arch, or and anchor rope combined Steel Arch Support, surrounding rock grouting, etc; Although this can achieve certain supporting effect, but support cost is very high. Therefore, China coal group design to create a new type of flat net shell components, the main supporting characteristics of flat net shell components summed up as: "while digging, while supported edge, before soft to hard, enough stiffness, process simple,low price."
1,"While digging, while supported edge",Steel Arch Support
Flat Net Shell Support can use waste rock filling, grey package after wall, concrete precast slab, such as filling, network frame and the tunnel contour quickly close to stick, while digging, timely support, so that on the one hand can make the support resistance of support was able to play in time, to timely reinforce the surrounding rock and to work under the stress state in three; On the other hand, have the effect of slow pressure, pressure, lead to the uniform support along the perimeter stress, is in good working condition.
2,Flat Net Shell Support has enough "rigidity"
3,"Just moderately soft, before soft to hard".
Flat Net Shell Support force has a complex ingredients: expansion and creep of rock mass, reduce the strength of long, crushing of rock mass adhesion coefficient reduced values, etc., all show the macroscopic displacement of rock mass and any rigid support to prevent displacement will be entirely itself in disadvantage. Therefore, the stability of the laneway to end support, work together to complete of the surrounding rock. Reticulated shell scaffold, while under high in-situ stress reaction in surrounding rock, making convergence of surrounding rock in supporting under the control of convergence, by stent supported edge, the edge of broken rock mass convergence pressure unceasingly, forming a stable bearing ring, together with stents to assume the role of in-situ stress.
The scalability of Flat Net Shell Support comes from two aspects:
(1) the contact of the spatial grid Steel Arch Support and surrounding rock itself has certain yielding;
(2) the junctions between the reticulated shell scaffold piece and piece of wood plate.
