A method for controlling the stability of the surrounding rock of a water-rich soft rock roadway by filling and water control

Abstract

The present invention discloses a method for controlling the stability of the surrounding rock of a water-rich soft rock roadway through filling and water control. First, collect the geological and hydrogeological information and the law of mine pressure manifestation in the area of the water-rich soft rock roadway, and complete the work such as water exploration and drainage and determination of the cross-section shape before roadway excavation. Then, use the method of long grouting anchor cables + short hollow anchor bolts to anchor and grout the deep and shallow rock layers of the roof respectively and pump in desiccants, and use short hollow anchor bolts for the two sides to anchor and pump in desiccants to ensure sufficient dryness in the shallow part. Finally, dig water-conducting boreholes at the bottom corners of the two sides, spray the surface of the roadway, and reinforce the floor with concrete. This method can reinforce and control water in the water-rich soft rock, effectively improve the strength of the soft rock, and through macroscopically regulating the underground water flow direction artificially, reduce the intrusion of underground water into the soft rock of the roadway, so as to effectively control the stability of the surrounding rock of the water-rich soft rock roadway.

Description

Technical Field

[0001] The present invention relates to the technical field of coal mine roadway support, and particularly relates to a method for controlling the stability of the surrounding rock of a water-rich soft rock roadway by filling and controlling water. Background Art

[0002] Generally, the geological structure of a water-rich soft rock roadway is relatively complex, the coal seam occurrence conditions are poor, the coal seam, roof and floor are all relatively soft (compressive strength less than 25 MPa), the load-bearing deformation is large, and it has long-term rheological properties, strong water swelling property and disintegration property. The coal mine soft rock roadway engineering is an important part of the soft rock engineering. In the coal-bearing strata of coal mines in China, the mines with soft rock are widely distributed. In addition to its own lithology, mechanical properties, geological conditions, working face conditions, etc., the stability of the surrounding rock of the water-rich soft rock roadway is greatly affected by groundwater and engineering water. After water infiltrates into the surrounding rock, it will produce a hydrostatic pressure effect, which deteriorates the stress state in the rock mass, reduces the effective compressive stress and shear strength; after the infiltrating water invades the rock mass rich in minerals, a series of physical and chemical reactions will occur, and the friction coefficient and cohesion of the fracture surface will be reduced, which will cause the surrounding rock to become muddy, disintegrate and expand. Although some scholars have carried out a large number of field and theoretical studies based on different geological conditions, there is still a lack of a more universal and effective support method for water-rich soft rock roadways. Summary of the Invention

[0003] The purpose of the present invention is to provide a method for controlling the stability of the surrounding rock of a water-rich soft rock roadway by filling and controlling water, which can enhance the strength of the soft rock on the one hand and reduce the influence of water on the surrounding rock anchoring area on the other hand, so as to ensure the safety of this type of roadway during its service period.

[0004] To achieve the above purpose, a method for controlling the stability of the surrounding rock of a water-rich soft rock roadway by filling and controlling water according to the present invention includes the following steps:

[0005] S01. Collect hydrogeological data, and based on the previous geological exploration report and the hydrogeological conditions of adjacent mining areas and working faces, conduct pre-drainage and water exploration work on the strong water-rich soft rock roadway before excavation;

[0006] S02. Determine the roadway section shape and excavate the roadway based on the mine pressure manifestation law of adjacent roadways in the mining area;

[0007] S03. Support the roof of the excavated roadway by using long grouting anchor cables + short hollow bolts. After the long grouting anchor cables are anchored, grouting and filling are carried out into the deep surrounding rock, and after the short hollow bolts are anchored, desiccants are pumped into the shallow surrounding rock;

[0008] S04. After the roof support is completed, support the two sides by using short hollow bolts, and after the anchoring is completed, desiccants are pumped into the two sides;

[0009] S05. At certain intervals at the bottom corners of both sides, water-conducting boreholes with a certain depth are excavated towards both sides respectively. The water-conducting boreholes are fixed with metal pipes closely attached to the hole walls. The roadway floor is treated with concrete solidification. At the same time, water-conducting grooves are excavated near both sides to drain the water from the water-conducting boreholes on both sides.

[0010] S06. After the support is completed and when there is no longer any dripping water on the roadway surface, shotcreting treatment is carried out on the roof and both sides.

[0011] S07. After the support and filling water control are completed, a relatively closed water-resistant space is formed in the roadway. During the mining period, dynamic monitoring is carried out on the surface displacement of the roadway surrounding rock, roof separation, pore fracture structure and roadway water inflow situation, and certain reinforcement support measures are taken.

[0012] Furthermore, in step S02, the roadway cross-section shape is rectangular, semi-circular arch, elliptical or irregular shape. Among them, for roadways with good lithology, simple geological and hydrogeological conditions and small mine pressure manifestations, rectangular roadways are selected; otherwise, semi-circular arch roadways are selected. The cross-section properties and dimensions of the roadway meet the requirements of support and ventilation.

[0013] Furthermore, in step S03, the long grouting cable bolt model is φ22×7000mm, and the short hollow bolt model is φ28×2300mm.

[0014] Furthermore, in step S03, the filling material for the deep surrounding rock by the long grouting cable bolt is ultrafine cement with an average particle size less than 5um, and the main components of the desiccant pumped into the shallow surrounding rock by the short hollow bolt are calcium chloride and glue starch.

[0015] Furthermore, both the ultrafine cement and the desiccant are pumped into the surrounding rock by a pneumatic pump, and the pumping pressure of the pneumatic pump does not exceed 5MPa.

[0016] Furthermore, in step S05, the size of the water-conducting boreholes excavated at the bottom corners of both sides is φ32×10000mm, the interval of the water-conducting boreholes is 10m, and the interval can be adjusted according to the water inflow.

[0017] Furthermore, in step S05, the cement used for solidifying the roadway floor is C15 strength concrete.

[0018] Furthermore, in step S06, the main components of the shotcreting material on the roadway surface are cement and quartz sand.

[0019] Furthermore, in step S07, the layout interval of the mine pressure monitoring stations during the mining period is 20 - 50m; each monitoring station includes two roof separation monitoring points, three roof surrounding rock structure monitoring points, and four rib surrounding rock structure monitoring points.

[0020] The beneficial effects of the present invention are as follows: The roadway surrounding rock stability control method proposed by the present invention can construct a low water content layer with relatively high strength in the surrounding rock area of water-rich soft rock roadways, thereby effectively controlling the stability of the surrounding rock. On the one hand, after injecting ultra-fine cement slurry into the deep rock formation through long grouting anchor cables, a large number of pore fissures existing in the surrounding rock are blocked, reducing the space for water intrusion in the later stage. At the same time, after the slurry solidifies, the strength of the deep surrounding rock is effectively enhanced, forming a relatively closed layer within the roadway anchorage area. On the other hand, desiccants are pumped into the shallow rock formation through short hollow anchor bolts to adsorb the water existing in the closed layer. At the same time, under the relatively dense layout, the strength of the shallow surrounding rock is also enhanced. Finally, considering that completely isolating the water flow will cause strong pressure on the anchorage area, water-conducting boreholes are excavated at the two side bottom corners to macroscopically regulate the underground water flow direction artificially, so as to effectively control the stability of the surrounding rock of the water-rich soft rock roadway. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is the step flow chart of the roadway surrounding rock stability control method of the present invention;

[0022] Figure 2 is the roadway support section view;

[0023] Wherein, a - long grouting anchor cable, b - short hollow anchor bolt, c - water-conducting borehole. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] The present invention will be further described in detail below with reference to the drawings and specific embodiments.

[0025] As Figure 1 shown, an embodiment of the present invention is a roadway surrounding rock stability control method for water-rich soft rock roadways by filling and controlling water, including the following steps:

[0026] S01. Collect hydrogeological data. Based on the previous geological exploration report and the hydrogeological conditions of adjacent mining areas and working faces, pre-drainage work is carried out for the strongly water-rich soft rock roadway before excavation.

[0027] S02. Based on the law of mine pressure manifestation in adjacent roadways of the mining area, before excavating a new roadway, it is necessary to combine geological exploration data, roadway use requirements, and the severity of mine pressure manifestation (such as surface displacement, roof separation, stress on anchor cables, etc.) after the excavation of the adjacent roadway section shape and working face, whether it affects normal production and safety, and then comprehensively determine the roadway design parameters, such as determining the roadway section shape and excavating the roadway. The roadway section shape can be rectangular, semi-circular arch, elliptical or irregular shape. For roadways with good lithology, simple geological and hydrogeological conditions and small mine pressure manifestation, rectangular roadways are preferably considered first, and vice versa, semi-circular arch roadways are preferably selected. The nature and size of the roadway section need to meet the use requirements such as support and ventilation. The roadway shape in this embodiment is rectangular.

[0028] For S03, the roof of the well - driven roadway is supported by long grouting anchor cables + short hollow anchor bolts. After the long grouting anchor cable a is anchored, grout is injected into the deep surrounding rock for filling. After the short hollow anchor bolt b is anchored, desiccant is pumped into the shallow surrounding rock. By injecting grout into the deep part of the roof through the long grouting anchor cable a, on the one hand, a large number of pore - fissures in the surrounding rock are effectively sealed, reducing the space for later water intrusion. At the same time, after the grout solidifies, the strength of the deep surrounding rock is effectively enhanced, forming a relatively closed layer within the roadway anchorage area. By pumping desiccant into the shallow rock layer through the short hollow anchor bolt b, the moisture existing in the closed layer is adsorbed. At the same time, under the relatively dense layout, the strength of the shallow surrounding rock is also strengthened. As Figure 2 shown, in this embodiment, on a roadway support cross - section with a length × width of 4400×2700 mm, the spacing of the short hollow anchor bolts b is 800 mm, and the spacing of the long grouting anchor cables a is 1600 mm. Along the length direction of the roadway, an anchorage grid composed of multiple rows of long grouting anchor cables and multiple rows of short hollow anchor bolts is formed. The model of the long grouting anchor cable a is φ22×7000 mm, and the length of the anchor cable can be appropriately extended according to actual conditions. The model of the short hollow anchor bolt b is φ28×2300 mm. The filling material for the deep surrounding rock by the long grouting anchor cable a is ultrafine cement with an average particle size less than 5 μm. The main components of the desiccant pumped into the shallow surrounding rock by the short hollow anchor bolt b are calcium chloride and starch gum. Both the ultrafine cement and the desiccant are pumped into the surrounding rock through a pneumatic pump, and the pumping pressure of the pneumatic pump does not exceed 5 MPa.

[0029] For S04, after the roof support is completed, short hollow anchor bolts are used to support the two sides, and desiccant is pumped into the two sides after anchoring; the short hollow anchor bolts b on the two sides are generally drilled perpendicular to the side wall, and the spacing between two short hollow anchor bolts b is 800 mm.

[0030] For S05, in order to prevent water seepage in the roof or the two sides, it is necessary to drain the water after the above reinforcement. It is necessary to dig about 10 - m long water - conducting boreholes c in the two - side bottom corners at intervals along the two sides respectively. The water - conducting boreholes c are fixed with metal pipes closely attached to the hole wall to prevent shrinkage or complete closure during the drilling work. The water - conducting boreholes c should have a certain inclination angle, and the inclination angles of each water - conducting borehole can be inconsistent. The roadway floor is treated with concrete solidification, and at the same time, water - conducting grooves are dug near the two sides respectively to drain the water from the water - conducting boreholes c on the two sides; among them, the cement used for solidifying the roadway floor is C15 - strength concrete specified in the "Code for Design of Concrete Structures" (GB50010 - 2010).

[0031] For S06, after the support is completed and when there is no longer water dripping on the roadway surface, shotcrete treatment is carried out on the roof and the two sides. Through shotcrete, the cracks on the surface of the coal - rock layer can be effectively sealed, further isolating the influence of water.

[0032] After the support and filling water control of S07 are completed, a relatively closed water - proof space is formed in the roadway. During the mining period, the surface displacement of the roadway surrounding rock, roof separation, pore - fracture structure and the water inflow situation of the roadway are dynamically monitored, and certain reinforcement support measures are taken. The dynamic monitoring is to set up multiple mine pressure monitoring stations in the roadway. Specifically, during the mining period, the layout interval of the mine pressure monitoring stations is 20 - 50 m. Each monitoring station includes two roof separation monitoring points, three roof surrounding rock structure monitoring points, and four rib surrounding rock structure monitoring points.

[0033] Through the above steps, the effective control of the stability of water - rich soft rock is realized. That is, through steps S01 - S06, a manual water - control system for the water - rich soft rock roadway is formed by long grouting anchor cables for grouting (forming the first - layer water - proof layer), short hollow anchor bolts for pumping desiccant (forming the second - layer water - proof layer), surface shotcrete (forming the third - layer water - proof layer), and directional water - guiding of the water - proof ring. Through step S07, multi - point monitoring of the above - mentioned water - control system is carried out to take further strengthening support measures.

[0034] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited thereto. All changes that can be made within the knowledge of those skilled in the art of the relevant technical field without departing from the gist of the present invention fall within the protection scope of the claims of the present invention.

Claims

1. A method for controlling the stability of the surrounding rock of a water-rich soft rock roadway by filling and water control, characterized in that It includes the following steps: S01. Collect hydrogeological data. Based on the previous geological exploration report and the hydrogeological conditions of adjacent mining areas and working faces, pre-drainage work is carried out before the excavation of strongly water-rich soft rock roadways; S02. Determine the roadway section shape and excavate the roadway based on the law of abutment pressure manifestation in adjacent roadways of the mining area; S03. The roof of the excavated roadway is supported by long grouting anchor cables + short hollow anchor bolts. After the long grouting anchor cables are anchored, grouting is carried out to fill the deep surrounding rock, and after the short hollow anchor bolts are anchored, desiccant is pumped into the shallow surrounding rock; S04. After the roof support is completed, the two sides are supported by short hollow anchor bolts, and desiccant is pumped into the two sides after anchoring; S05. At certain intervals at the bottom corners of the two sides, water-conducting boreholes with a certain depth are excavated into the two sides respectively. The water-conducting boreholes are fixed with metal pipes close to the hole wall. The roadway floor is treated with concrete solidification. At the same time, water-conducting grooves are excavated near the two sides respectively to drain the water from the water-conducting boreholes on the two sides; S06. After the support is completed and when there is no longer water dripping on the roadway surface, shotcreting is carried out on the roof and the two sides; S07. After the support and filling for water control are completed, a relatively closed water-resistant space is formed in the roadway. During the mining period, dynamic monitoring is carried out on the surface displacement of the roadway surrounding rock, roof separation, pore fracture structure and roadway water inflow conditions, and certain reinforcement support measures are taken.

2. A method for controlling the stability of the surrounding rock of a water-rich soft rock roadway by filling and controlling water, as described in claim 1, characterized in that, In step S02, the roadway section shape is rectangular, semi-circular arch, elliptical or irregular shape. Among them, for roadways with good lithology, simple hydrogeological conditions and small abutment pressure manifestation, rectangular roadways are selected, otherwise semi-circular arch roadways are selected. The roadway section properties and dimensions meet the requirements of support and ventilation use.

3. The method for controlling the surrounding rock stability of a water-rich soft rock roadway by filling and water control according to claim 1, characterized in that In step S03, the model of the long grouting anchor cable is φ22×7000 mm, and the model of the short hollow anchor bolt is φ28×2300 mm.

4. The method for controlling the surrounding rock stability of a water-rich soft rock roadway by filling and water control according to claim 1, characterized in that In step S03, the filling material for the deep surrounding rock of the long grouting anchor cable is ultrafine cement with an average particle size less than 5 μm, and the main components of the desiccant pumped into the shallow surrounding rock by the short hollow anchor bolt are calcium chloride and starch glue.

5. A method for controlling the surrounding rock stability of a water-rich soft rock roadway by filling and water control according to claim 4, characterized in that, Both the ultrafine cement and the desiccant are pumped into the surrounding rock by a pneumatic pump, and the pumping pressure of the pneumatic pump does not exceed 5 MPa.

6. The method for controlling the surrounding rock stability of a water-rich soft rock roadway by filling and water control according to claim 1, characterized in that, In step S05, the size of the water-conducting boreholes excavated at the bottom corners of the two sides is φ32×10000 mm, and the interval of the water-conducting boreholes is 10 m, and the interval can be adjusted according to the water inflow.

7. The method for controlling the stability of the surrounding rock of a water-rich soft rock roadway by filling and water control according to claim 1, characterized in that In step S05, the cement used for the solidification of the roadway floor is C15 strength concrete.

8. A method for controlling the stability of the surrounding rock of a water-rich soft rock roadway by filling and controlling water, as described in claim 1, characterized in that In step S06, the main components of the shotcreting material on the roadway surface are cement and quartz sand.

9. The method for controlling the surrounding rock stability of a water-rich soft rock roadway by filling and water control according to claim 1, characterized in that, In step S07, the layout interval of the abutment pressure monitoring stations during the mining period is 20 - 50 m; each monitoring station includes two roof separation monitoring points, three roof surrounding rock structure monitoring points, and four two-side surrounding rock structure monitoring points.

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