CN101260672B - Grouting method for rocky slope with weak surface and anchor pipe used for grouting - Google Patents

Abstract

The invention discloses a weak-plane rock side slope grouting method and an anchor pipe for grouting. An anchor hole is drilled; the diameter of the anchor hole is more than the outside diameter of the anchor pipe body of at least 100 mm; the anchor pipe is placed in the anchor hole; concrete is filled in the anchor hole mouth; suspended grout in a double layer stirring mill is pressed to the anchor pipe for grouting by a grouting pump; when the grouting flow rate is more than the flow rate of grout absorption by rock or the grouting pressure is larger than the shearing resisting intensity of fissure filling in a shallow layer rock body, a grout returning valve is started in order that the grout in the hole returns to a grout storage barrel of the double layer stirring mill for circulating grouting. The weak-plane rock side slope grouting method and the anchor pipe for grouting effectively solve the difficult problems that the prior pressing in type grouting is easy to leak the grout, can not completely fill the fissure and can not be suitable for reinforcing the shallow layer. The circulating grouting method of the invention enlarges the grouting scope, improves the injection rate by the single hole, can effectively reinforce the water seepage and corrosion resisting capacity in the interlayer of the side slope and improve the stabilizing capacity of the whole side slope. The anchor pipe of the invention has the advantages of simple structure, easy manufacture and low costs.

Description

Grouting method for rocky slope with weak surface and anchor pipe used for grouting

technical field

The invention relates to a rock mass internal reinforcement method and a device used in geotechnical engineering, in particular to a grouting reinforcement method and a grouting device used for rock slopes with weak interlayers. the

Background technique

In geotechnical engineering, rocky slopes with weak interlayers are prone to landslides under the action of rainfall and groundwater. At present, in order to prevent shallow landslides caused by water erosion piping on weak interlayer rock slopes, there are mainly two reinforcement methods used: one is the combined method of bolt reinforcement rock formation and shotcrete sealing slope surface; the other It is used for high-pressure grouting in rock formations to fill karst caves, faults, weak interlayers and joint fissures. the

There are serious shortcomings in the joint reinforcement method of anchor bolt and spray mix: the temperature difference between the atmosphere and the rock layer causes the concrete shell on the slope to swell and produce cracks and separation layers, resulting in sealing failure and rainwater infiltration; the anchor bolt grouting cannot fill the weak surface Interlayer, water seepage corrodes the anchor rod body, shortens the service life of the anchor rod, and leaves a safety hazard. the

The grouting tools for rock formation high-pressure grouting include self-drilling bolts and double-layer pipes (or double-layer pipes). Self-drilling bolts are usually used in difficult-to-pore formations such as weathered rocks, gravel layers, backfill layers, gravel layers, and pebble layers. The self-drilling bolt should provide two performances of grouting hollow channel and steel brazing torque, and the special steel used increases the cost of the bolt; the self-drilling bolt has only one grouting channel, which can only be used for press-in grouting. pulp. Double-layer or dual-type grouting pipes are used for deep positioning grouting where two kinds of grout with different properties are injected at the same time. Due to the special pipe material, complex structure and high cost, it can only be press-in grouting and cannot be used as an anchor to strengthen the rock formation. the

The press-in grouting is a grouting method that pushes the grout to force the interlayer filling and fill the rock formation fissures by means of external pressure. The press-in grouting process has three disadvantages in shallow grouting: First, there is no soil-covering grouting layer for shallow grouting on the slope. If the grouting pressure cannot be adjusted, the slope will run out of grout, and the slope will crack. The filling is not enough; the second is that the shallow slope rock layer loses water seriously, and the grout loses water in the flow process of the anchor hole and the rock layer, and the fluidity becomes poor, which blocks the grouting channel; the third is that the grout cannot return when the injection is stopped, and the anchor hole is blocked. Resulting in the inability to reperfuse. the

Contents of the invention

The purpose of the present invention is to solve the problem that the grouting of the weak surface shallow rock mass is easy to run out of grout and the filling of the cracks is not enough. method, and provide an anchor pipe for circulating grouting. the

The detailed technical scheme of the present invention for the circulating grouting method of the shallow rock mass of the weak surface rock slope is as follows: drill the anchor hole, the diameter of the anchor hole is 100mm larger than the outer diameter of the anchor pipe; Anchor pipe, fill concrete in the anchor hole orifice; use a grouting pump to hydraulically inject the suspended grout in the double-layer mixer into the anchor pipe for grouting; during the grouting process, adjust the grouting flow through the grouting valve and the grouting valve according to the stability of the rock formation and grouting pressure; when the grouting flow rate is greater than the rock grouting flow rate or the grouting pressure is greater than the shear strength of shallow rock fissure fillings, start the grout return valve to return the grout in the hole to the slurry storage tank of the mixer through the grout return pipe , cyclic grouting. the

The anchor pipe used in the above method is composed of an anchor head, an anchor pipe body and a grouting hole on the anchor pipe body. A backing plate and a nut are arranged on the anchor head as a prestressing device, and a grout stopper is set at a distance of 600mm to 1000mm from the backing plate. The lower part of the stopper is connected to the inlet of the slurry return pipe, and the outlet extends to the outside of the anchor hole to connect to the slurry storage barrel of the double-layer mixer. the

Using the anchor pipe of the present invention, a circulating grouting channel is formed in the anchor hole, which can not only effectively maintain the water content of the grout during grouting, but also reduce the disturbance to the slope rock formation by adjusting the grouting pressure and flow rate. Especially when there is no overlying soil layer and the grout on the slope needs to be treated, clean water can be injected to flush the anchor hole to prevent the grout from solidifying and blocking the anchor hole. This not only reserves the channel for repeated grouting in the subsequent stages, but also seals the slope by splitting grouting. The cracks on the surface create conditions for the post-sequence grouting to increase the pressure, thus effectively solving the problems of traditional press-in grouting, grout running out, and crack filling dissatisfaction, which cannot be applied to shallow reinforcement. Moreover, the anchor pipe of the present invention can be made of ordinary hollow steel, has a simple structure, is easy to manufacture, and has low cost. the

Compared with the existing slope reinforcement grouting method, the circulating grouting method adopted in the present invention not only maintains the simple and feasible characteristics of traditional anchoring construction, but also realizes the splitting grouting of interlayer clay to close the slope cracks by increasing the opening grouting pressure, Create conditions for repeated grouting to increase the grouting pressure; control the grouting pressure and flow through subsequent grouting, expand the grouting range, and increase the single-hole grouting injection rate. Adopting the circulating grouting method of the present invention can effectively enhance the water seepage resistance and water erosion resistance of the slope interlayer, and improve the overall stability of the slope. the

This invention not only provides a method of strengthening and remediating geological disasters from the shallow layer inside the rock mass for weak interlayer rock slopes and soft rock, broken rock mass, and gravel and pebble interbedded slopes in industries such as transportation, water conservancy, energy, and construction. The anchor injection method not only creates conditions for slope ecological protection and eliminates the traces of artificial construction in geotechnical engineering, but also eliminates the hidden danger of early failure of reinforcement projects due to anchor corrosion. the

Description of drawings

Fig. 1: schematic diagram of anchor pipe structure of the present invention;

Fig. 2: the sectional structural diagram that carries out circulating type grouting with the anchor pipe of the present invention;

Fig. 3: Process flow chart of embodiment 2 circulation grouting method. the

Detailed ways

Example 1

use The anchor pipe body (6) is made of ordinary straight seam welded pipe, the first row of grouting holes (8) is drilled from the hole bottom 20cm, the centering bracket (7) is welded at the bottom of the hole, and the grouting holes are drilled every 20 (8 ), and respectively weld the centering bracket (7) on the upper section and the middle section of the anchor pipe body (6). Set a backing plate and nut (2) on the anchor head (1) as a prestressing device, set a stopper (4) at a distance of 800mm from the backing plate (3), and the lower part of the stopper is connected to the inlet of the grout return pipe (5). The grout return pipe outlet extends out of the anchor hole.

Example 2

The left slope of an expressway section is a broken limestone slope with clay interlayer. The slope is 240m long and the maximum height is 39.6m, which is a forward slope. The slope is divided into four levels, each level of slope is 10m high, and the slope ratio is 1:0.75～1:1. The slope is cut by four groups of joints and several faults, and the groundwater of the natural slope at the top of the slope penetrates into the faults and fissures, causing the interlayer clay to soften and lose, and shallow rock strata to slip along the bed. The owner of the expressway requires ecological protection on the slope, no shotcrete, and shallow reinforcement of the slope. The process flow shown in Figure 3 is used to implement circular grouting. the

As shown in Figure 2, after cleaning the side slope, the anchor hole with a diameter of 54 mm and a depth of 4 to 6 m is drilled, and the diameter of the anchor hole is 100 mm larger than the outer diameter of the anchor pipe body (6). Clean the slag in the hole with high-pressure water, put the anchor pipe made in embodiment 1, install the grout stopper (4) at the position of the depth of 600mm in the anchor hole opening, and then fill the concrete (9). A backing plate (3) and a nut (2) are installed at the position where the anchor head (1) is flush with the side slope. 52.5 ordinary Portland cement, cohesive soil, and fly ash are used as slurry materials for the suspension slurry, and the suspension slurry is prepared by stirring with a double-layer mortar mixer. Use a grouting pump to hydraulically inject the suspended grout into the anchor pipe, and set a pressure gauge (12) and a grouting valve (10) at the entrance of the anchor pipe. The suspended grout enters the anchor hole through the grouting hole (8), and a part of the grout in the hole is squeezed into the interlayer crack of the weak surface. During the grouting process, the grouting flow rate and the grouting pressure are adjusted according to the stability of the rock formation and the pressure gauge. When the slurry delivery flow rate is greater than the rock slurry suction flow rate or the grouting pressure is greater than the shear strength of the shallow rock mass fissure filling, start the slurry return valve (11) on the slurry return pipe (5) to return the slurry in the hole to the mixer. The grout storage tank realizes circulating grouting. After the grout stone body in the hole shrinks, the grout is replenished and the concrete lattice beam is poured. After the lattice beam strength reaches 70% of the design strength, tighten the nut (2) to apply prestress. the

The slope rock mass after grouting with the method of the present invention adopts acoustic detection and drilling to get core samples, and the results show that the sound wave velocity of the rock mass has increased by 10% to 27% in the range of 1.9m away from the center of the anchor hole. The radius of the hole low-pressure circulation grouting exceeds 1.9m. After four years, the stability of the slope was good, and there were many local landslides in the adjacent non-grouting slope. the

On the same slope, the press-in grouting and circulation grouting were compared and tested, and the results showed that:

① The press-in grouting method uses a water-cement ratio of 2:1 or 1.5:1 to start grouting. Under the conditions of a water-cement ratio of 1.5:1 and a maximum grouting pressure of 1.6Mpa or more, normal grouting can last for 25 to 30 minutes. The circulating grouting method can obtain a large grouting flow rate by using a grouting pressure of 0.05MPa and a water-cement ratio of 2:1. Duration 40min. the

② When the grouting pressure reaches 1.6 MPa in the area with no joints, the hydraulic splitting and running of shallow fissures will occur; in the area with developed joints, when the grouting pressure reaches 0.2 MPa, the grouting may split and cause the surface to erupt. the

③Anchor holes using circulating grouting method are injected with 200L more solid material than single holes using press-in grouting method. the

Claims (4)

1. a Weak surface rock slope grouting method is characterized in that comprising the steps: the Drilling anchor hole, and described anchor hole diameter is than anchor tube body diameter 100mm greatly at least; Centering is put into anchor tube in anchor hole, the filling concrete; With grouting pump the suspension slurry in the double-deck mixer is pressed into anchor tube slip casting; When defeated slurry flow is inhaled slurry flow or grouting pressure greater than the shear strength of shallow-layer rock cranny charges greater than rock, start the slurry traversing valve on the return pipe, make slurries in the hole return the slurry storing tank of double-deck mixer, circulation slip casting by return pipe; Treat to mend slurry after slurries calculus soma contracts in the hole, the fluid concrete lattice beam, when lattice beam intensity reach design strength 70% after, apply prestressing force.

2. the method for claim 1 is characterized in that: in the slip casting process, regulate flow rate of grouting and grouting pressure according to rock stratum stability by grouting valve and slurry traversing valve.

3. the anchor tube that is used for the described grouting method of claim 1, form by the injected hole on anchor head, anchor tube body and the anchor tube body, it is characterized in that: described anchor head periphery is provided with screw thread, the nut that backing plate is set in the position of the flat side slope of anchor head part and adapts with screw thread is as the prestressing force bringing device, apart from backing plate 600mm～1000mm place stop grouting plug is set, connect the return pipe inlet on the anchor tube body under the stop grouting plug, the return pipe outlet extends to the outer slurry storing tank that connects double-deck mixer of anchor hole, establishes slurry traversing valve on the return pipe.

4. anchor tube as claimed in claim 2 is characterized in that: be welded with medium-height trestle on the described anchor tube body.

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