The construction principle of the pipe umbrella system is to use various means to control the deformation of the surrounding rock and maximize the protection and mobilization of the self-supporting capacity of the surrounding rock. Obviously, the construction of the pipe umbrella is to grout the surrounding rock through the steel pipe to reduce the porosity of the soil and increase the compactness of the soil, so that the slurry bubbles play a skeleton role in the soil or the slurry and the soil condense into a shell. The integrity of the soil structure is maintained and the physical strength of the soil is improved, thereby enhancing the self-supporting capacity of the weak surrounding rock and controlling the deformation of the surrounding rock in a timely and effective manner.
So, what kinds of grouting processes are there in the pipe umbrella system? What are the characteristics of each grouting process? Today, Sinorock will give you a detailed introduction.
Small Conduit Grouting
The small pipe grouting method is a basic type of tunnel advanced support. It is a method of short-distance advanced pre-support. It is generally suitable for the short-term stability of the face or the low self-stabilization ability of the surrounding rock and less water. The exposed ends are often supported on the steel frame behind the excavation face to form a pre-support system, which has a general effect of controlling surface settlement, general anti-seepage and water-stopping effect, and general construction technology requirements, and low cost.
Long Tube Shed Grouting
Long pipe shed grouting is another basic type of pipe shed advance pre-support. Compared with the small pipe grouting method, it is a long-distance advanced pre-support method. Due to the long advanced distance and high rigidity, it is suitable for strata that cannot be self-stabilized and contain water, they often form a pre-support system together with a steel frame, which has better control of surface subsidence, better anti-seepage, and water-repellent effects, higher construction technology requirements, and higher construction costs.
Long Pipe Shed Grouting + Small Pipe Supplementary Grouting
In addition to the above-mentioned characteristics of grouting in the long pipe shed, this method can prevent the slump of the triangular soil body under the pipe shed, and the pre-support effect of this combination of long and short is better.
Horizontal Jetting Pile Pre-Support
Horizontal jetting pile pre-support is a new type of long-distance advanced pre-support method. It has long advanced distances and high rigidity. It is suitable for the stratum where the face cannot be self-stabilized and is rich in water. It forms a pre-support system together with the steel frame to control the ground surface. The effect of settlement is good, the effect of preventing seepage and preventing water is good, the construction technology requirements are high, and the cost is high.
Horizontal Rotary Spray Pile + Small Pipe Supplementary Grouting
In addition to the characteristics of the horizontal spraying pile, this method can prevent the slump of the triangular soil under the spraying pile. The pre-support and anti-seepage effects of this combined system are ideal.
Self-Drilling Hollow Rock Bolt Grouting
Self-drilling hollow rock bolt is a new type of support material, which realizes simultaneous drilling and grouting. It can be constructed efficiently under weak, broken and other geological conditions that are not easy to form holes. The self-drilling hollow rock bolt adopts pressure grouting, which can fully fill the rock fissures and improve the stability of the surrounding rock.
At present, advanced pre-support technology has been widely used in underground projects such as highway tunnels, railway tunnels, urban subways, and underground passages. Due to its characteristics of simple operation, flexible and convenient transportation, and installation of construction equipment, the use of pipe shed advanced pre-support technology in mountain tunnels is more advantageous.