Distributed pressure-grouting device and method for bridge approach pile foundation

Abstract

A distributed pressure-grouting device and method for a bridge approach pile foundation. The device comprises a pressure-grouting pipe, grout outlet valves, and a grout stop valve. The grout stop valve comprises a grouting pipe and a pressure-charging pipe, wherein one end of the grouting pipe is connected to a grouting pump by means of a grout supply pipe, and the other end thereof is a closed end; the middle of the grouting pipe is provided with a grout outlet; and the two ends of the grouting pipe are respectively sleeved with balloons, the balloons positioned at the two ends of the grouting pipe are connected in series by means of the pressure-charging pipe, and the two balloons respectively seal two sides of one grout outlet valve, so that the grouting pipe, the grout outlet, and the corresponding grout outlet valve form a grouting channel. Independent grouting can be carried out for different grout outlet valves by means of providing the grout stop valve, thereby ensuring the grouting effect and improving the anti-settlement performance of a pile body after grouting.

Description

Background Field of the Invention The present invention relates to the technical field of bridge pile foundation construction, and in particular to a distributed pressure-grouting device and method for a bridge approach pile foundation. Background Information The cast-in-place bored pile technology is widely used in the field of engineering construction. In the past 20 years, with the rapid development of infrastructure in China, the requirements for the bearing capacity of the foundation have become increasingly high, and the requirements for the bearing capacity of the pile body have also been continuously raised, and the post grouting technology can significantly improve the bearing capacity of the pile body and is widely used. In the existing technology, the grouting pipe is tied to the reinforcing cage and is injected through the grouting port on the side of the grouting pipe. When pouring the concrete into the pile body, the grouting pressure after each grouting is consistent, and it is not possible to adjust the grouting pressure for different elevation positions. Therefore, it is necessary to provide an improved technical solution for the above shortcomings in the prior art. SUMMARY It is an object of the present invention to provide a distributed pressure-grouting device and method for a bridge approach pile foundation to solve the above-mentioned deficiencies in the prior art. In order to achieve the above-mentioned object, the present application provides the following technical solutions: A distributed pressure-grouting device for a bridge approach pile foundation comprises a pressure-grouting pipe, a grout outlet valve, and a grout stop valve, a plurality of pressure-grouting pipes are correspondingly distributed on an inner side of reinforcing cage, and are uniformly distributed around a circumferential direction of the reinforcing cage, a plurality of grout outlet valves are uniformly distributed on the pressure-grouting pipe, and are extended radially to an outer circumferential surface of the reinforcing cage, the grout stop valve is correspondingly provided inside the pressure-grouting pipe, and is slidably assembled along an axial direction of the pressure-grouting pipe, the grout stop valve comprises a grouting pipe and a pressure-charging pipe, wherein one end of the grouting pipe is connected to a grouting pump by means of a grout supply pipe, and the other end of the grouting pipe is a closed end; the middle of the grouting pipe is provided with a grout outlet; and two ends of the grouting pipe are respectively sleeved with balloons, the balloons positioned at the two ends of the grouting pipe are connected in series by means of the pressure-charging pipe, and two sides of one of the grout outlet valves are sealed by two balloons respectively, so that a grouting channel is formed by the grouting pipe, the grout outlet and corresponding grout outlet valve. A distributed pressure-grouting method for a bridge approach pile foundation, which uses any one of the above-mentioned pressure-grouting device for pressure-grouting, wherein the distributed pressure-grouting method for a bridge approach pile foundation comprises: Step SI, synchronously binding the pressure-grouting pipe and the grout outlet valve during reinforcing cage processing; Step S2, placing the reinforcing cage to the bottom portion of the pile hole after the bottom portion is cleaned, and pouring concrete into the pile hole; Step S3, placing the grout stop valve into one of the pressure-grouting pipes, so that the grout outlet in a middle of the grout stop valve is faced to the lowest grout outlet valve of the pressure-grouting pipes; Step S4, supplying gas to two balloons, sealing two sides of the corresponding grout outlet valve after the two balloons are swelled, and supplying grout into the grouting pipe to form the grouting channel with the grouting pipe, the grout outlet and the corresponding grout outlet valve, so as to inject the grout into an outer circumference of the pile hole; and Step S5, injecting the grout into the grout outlet valve successively from bottom to top, and after grouting operations of all grout outlet valves in one of the pressure-grouting pipes are completed, performing the grouting of next pressure-grouting pipe until the grouting of all pressure-grouting pipes are completed. Advantageous effects: After the cast-in-place bored pile is completed, the liquid cement grout is pressed into the soil layer on the side of the pile by the pre-buried grout outlet valve, and the grout plays the role of penetration, filling, compaction, splitting and consolidation and the like on the mud skin around the pile to enhance the strength of the soil on the side of the pile, so as to improve the ultimate bearing capacity of the pile foundation and reduce the sinking capacity. Independent grouting can be carried out for different grout outlet valves by means of providing the grout stop valve, thereby ensuring the grouting effect and improving the anti-settlement performance of a pile body after grouting. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic diagram of the structure of the grouting device; Fig- 2 is a schematic diagram of the grouting of the lowest ring pipe; Fig. 3 is a schematic diagram of the grouting of the pile end; Fig. 4 is a diagram of the structure of the grout stop valve; Fig. 5 is a diagram of the structure of the grout outlet valve; Fig. 6 is a diagram of the structure of the grout outlet valve with the addition of the insertion pipe. In the drawings: 1-pressure-grouting pipe; 2-measuring tube; 3-grout outlet valve; 4- insertion pipe; 5-automatic pipe rolling machine; 6-grout stop valve; 7-backstop; 601-balloon; 602-pressu re-charging pipe; 603-gas supply pipe; 604-grouting pipe; 605-end plate; 701-rubber pipe. DETAILED DESCRIPTION OF EMBODIMENTS As shown in Figs. 1-6, a distributed pressure-grouting device for a bridge approach pile foundation comprises the pressure-grouting pipe 1, the grout outlet valve 3 and the grout stop valve 6, there are a plurality of pressure-grouting pipes 1, specifically the number of pressure-grouting pipes 1 is three to six, preferably the number pressuregrouting pipes 1 is four, a plurality of pressure-grouting pipes 1 are correspondingly distributed on an inner side of reinforcing cage, and are uniformly distributed around the circumferential direction of the reinforcing cage, and the pressure-grouting pipe 1 is fixed to the reinforcing cage by binding or welding. A plurality of grout outlet valves 3 are uniformly distributed on the pressure-grouting pipe 1, and are extended radially to an outer circumferential surface of the reinforcing cage. Furthermore, in order to ensure the grouting effect, the grout outlet valve 3 can extend radially from the outer circumferential surface of the reinforcing cage and then collide with the inner wall of the pile hole to improve the grouting effect. One grout outlet valves 3 are provided every 5m from the bottom of the pile on the same pressure-grouting pipe 1; the grout stop valve 6 is correspondingly provided inside the pressure-grouting pipe 1, and is slidably assembled along an axial direction of the pressure-grouting pipe 1, so as to enable the precise point grouting, and different grouting pressures can be applied at different elevations and different grouting quantities can be preset according to actual needs. A plurality of grout outlet valves 3 on the same vertical direction can be connected in series through the pressure-grouting pipe 1, so as to allow for grouting at the points of the plurality of grout outlet valves 3 at different elevations through one pressuregrouting pipe 1, so that different grouting pressures can be applied at different elevations and different grouting quantities can be preset according to actual needs. The grout stop valve 6 comprises the grouting pipe 604 and the pressure-charging pipe 602, the grout stop valve 6 is correspondingly provided inside the pressure-grouting pipe 1, and is slidably assembled along an axial direction of the pressure-grouting pipe 1. As the grout stop valve 6 slides along the pressure-grouting pipe 1, it can pass through a plurality of grout outlet valves 3, so as to allow for independent grouting for the grout outlet valve 3 at different points. The grouting pipe 604 is a metal pipe, one end of the grouting pipe 604 is connected to a grouting pump by means of a grout supply pipe for grouting, and the other end of the grouting pipe 604 is a closed end. The middle of the grouting pipe 604 is provided with a grout outlet which is one or more perforations, and the two ends of the grouting pipe 604 are respectively sleeved with balloons 601, the balloons 601 positioned at the two ends of the grouting pipe 604 are connected in series by means of the pressure-charging pipe 602, the balloons 601 are made of a rubber material and can be reused through inflation and deflation to inject grout into the point which is corresponded to each grout outlet valve 3. After inflating gas into the balloons 601, the balloons 601 swell and resist the inner wall of pressure-grouting pipe 1, so as to form the seal. The grout stop valve 6 is placed to the grout outlet valve 3 to be grouted, the upper side and lower side of grout outlet valve 3 are sealed by two balloons 601 respectively, so that a grouting channel is formed by the grouting pipe 604, the grout outlet and the corresponding grout outlet valve 3. A plurality of grout outlet valves 3 on the same pressure-grouting pipe 1 should be grouted from bottom to top. For a plurality of pressure-grouting pipes 1, the grouting can be performed in a clockwise, counterclockwise, or skip manner. The balloons 601 are cylindrical structure, and two ends of the balloons 601 are fixed to the grouting pipe 604 through an end plate 605 respectively, the end plate 605 is provided with the perforation which is corresponded to the grouting pipe 604 and is fixed by welding and sealing, and adjacent end plates 605 of two balloons 601 are communicated through the pressure-charging pipe 602, and a balloon 601 which is far away from the closed end of the grouting pipe 604 is correspondingly connected to an air pump through a gas supply pipe 603. The port of the pile hole is provided with an automatic pipe rolling machine 5 which is corresponded to the gas supply pipe 603 and / or the grout supply pipe. In order to ensure the driving effect, the grout supply pipe and the gas supply pipe 603 are integrally formed, or are connected as a whole by side wall bonding. At this time, the automatic pipe rolling machine 5 synchronously drives the combined gas supply pipe 603 and grout supply pipe. The grout outlet valve 3 is a three-way pipe which is correspondingly connected to the pressure-grouting pipe 1 that is a multi-segment pipe. The adjacent two ends of pressure-grouting pipe 1 are respectively connected to two ends of the main pipe of the grout outlet valve 3, and the grout outlet valve 3 can be connected to the pressuregrouting pipe 1 through threaded connection or welding. One pipeline of the three-way pipe (perpendicular to the middle pipe of the pressuregrouting pipe) is extended radially along the reinforcing cage, the middle pipeline end of the three-way pipe is provided with a backstop 7, and the backstop 7 is an elastic sleeve which is correspondingly sleeved on the middle pipeline end. The backstop 7 is a bottle cap-shaped rubber component that seals the middle pipeline of the grout outlet valve 3 through deformation. After the cement grout is pressurized, the backstop 7 forms a channel for the grout to flow out through deformation, thereby injecting grout around the pile body. In order to increase the grouting range, the insertion pipe 4 is inserted in the middle of the backstop 7. The insertion pipe 4 can be extended into a soil around pile body under pressure. Specifically, the end of the insertion pipe 4 corresponded to the grout outlet valve 3 is an open end, and the other end is a sharp sealing end. The inner wall of insertion pipe 4 located at the part of the grout outlet valve 3 near the end of the grout stop valve is provided with perforations. After pouring concrete into the pile body, the water is supplied through a grouting pump for opening, during opening process, high-pressure water is used to extend the sharp sealing end of the insertion pipe 4 outward into the soil around the pile body, and grouting is performed through the perforations on the side of insertion pipe 4 to improve the diffusion range and grouting effect of the grouting. The insertion pipe 4 is just an additional measure to increase the grouting effect. The presence or absence of the insertion pipe 4 does not affect the foundation grouting demand in the circumferential direction of the pile body. When the geological conditions are hard, or the required pressure of backstop 7 is less than the pressure of the insertion pipe 4 inserted into the soil, there may also be a situation where the backstop 7 is opened, but the insertion pipe 4 is not inserted into the soil around the pile body. At this time, grouting can only be performed through the backstop 7, and the cement grout passes through the thin layer of concrete between the inner wall of the pile hole and the backstop 7, it can also play a role in the circumferential grouting of the pile body. Therefore, in order to ensure that the insertion pipe 4 can be inserted into the surrounding soil of the pile body as much as possible, the opening operation is performed within 12-24 hours of pouring concrete into the pile, preferably 18 hours. At this time, the concrete has a certain strength, and the opened pile body concrete will not produce backflow to block the opening channel, which make the required pressure for opening greater. Therefore, it will drive the insertion pipe 4 to insert into the soil radially as much as possible. The end of the backstop 7 is provided with installation holes that are corresponded to the insertion pipe 4, the installation holes are in interference fit with the insertion pipe 4. The rubber pipe 701 that is correspondingly sleeved to the insertion pipe 4 is integrally formed on an inner side of the backstop 7, which extends along an axis direction of the backstop 7 to ensure that the concrete does not flow into the grout outlet valve 3 or the insertion pipe 4 during the grouting process. The outer diameter of the insertion pipe 4 shall not exceed two-thirds of the radial extension of the grout outlet valve 3 along the inner diameter of the pipeline, which ensure that grouting can still be performed through the gap between the insertion pipe 4 and the grout outlet valve 3 even if the insertion pipe 4 cannot extend. The closed end of the grouting pipe 604 is sealed in a detachable manner through a plunger for pile end grouting, and the grouting of the pile end is performed through the pressure-grouting pipe 1. The lower end of the pressure-grouting pipe 1 is a sharp sealing end, and after sinking the reinforcing cage into the pile hole, the lower end of the pressure-grouting pipe 1 is inserted into the soil at the bottom portion of pile hole, a part of side portion where the pressure-grouting pipe 1 is inserted into the bottom portion of the pile hole is provided with a pressure-grouting port, and the pressure-grouting pipe 1 is sleeved with a rubber sleeve which is corresponded to the pressure-grouting port. When grouting at the pile end through the grout stop valve 6, the plunger can be opened, after two balloons 601 raises, the grouting channel is formed through the end of the grouting pipe 604 and pressure-grouting port. Of course, a manual control valve can also be installed on the pressure-charging pipe 602. The manual control valve is closed and only allow the upper balloon 601 to rise, at this time, the cement grout can be injected into the pile end. The dual control of grouting volume and grouting pressure is implemented, with grouting volume control as the main method and grouting pressure control as a supplement. When grouting at the pile end, if the grouting amount of one pressuregrouting pipe 1 cannot meet the requirements and the grouting pressure is too high to continue grouting, the amount of cement that has not been pressed should be pressed in by the remaining pressure-grouting pipe 1 at the pile end. A distributed pressure-grouting method for a bridge approach pile foundation, which uses any one of the above-mentioned pressure-grouting device for pressure-grouting, wherein the distributed pressure-grouting method for a bridge approach pile foundation comprises: Step SI, synchronously binding the pressure-grouting pipe 1 and the grout outlet valve 3 during reinforcing cage processing; Step S2, placing the reinforcing cage to the bottom portion of the pile hole after the bottom portion is cleaned, and pouring concrete into the pile hole; Step S3, placing the grout stop valve 6 into one of the pressure-grouting pipes 1, so that the grout outlet in a middle of the grout stop valve 6 is faced to the lowest grout outlet valve 3 of the pressure-grouting pipes 1; Step S4, supplying gas to two balloons 601, sealing two sides of the corresponding grout outlet valve 3 after the two balloons 601 are swelled, and supplying grout into the grouting pipe 604 to form the grouting channel with the grouting pipe 604, the grout outlet and the corresponding grout outlet valve 3, so as to inject the grout into an outer circumference of the pile hole; and Step S5, injecting the grout into the grout outlet valve 3 successively from bottom to top, and after grouting operations of all grout outlet valves 3 in one of the pressuregrouting pipes 1 are completed, performing the grouting of next pressure-grouting pipe 1 until the grouting of all grouting pipes 1 are completed. In step S3, the grout outlet valve 3 is opened within 24 hours of concrete pouring, during opening, clear water is sequentially injected into the grout outlet valves 3 through the grout stop valve 6, and water injection is stopped after the water pressure drops, and the opening is completed. After concrete of pile body reaches 85% of design strength, an integrity of the pile body is tested by a measuring tube 2, and pressure-grouting amount corresponded to each grout outlet valve 3 is set based on test result. Each measuring tube 2 corresponds to one pressure-grouting pipe 1. In step SI, the measuring tube 2 is tied synchronously, and the measuring tube 2 is tightly attached to the pressure-grouting pipe 1. In order to ensure fixation strength, the connector is provided with perforations corresponding to the grouting pipe 1 and the measuring tube 2 respectively, which limit their relative positions and ensure the detection ability of the measuring tube 2 in the grouting area. During pressure-grouting, if the pressure-grouting amount of one of the grout outlet valves 3 in the pressure-grouting pipe 1 does not meet set requirement, the pressuregrouting amount that has not been injected should be injected by the grout outlet valve 3 on an upper side or lower side of the grout outlet valve. If the grouting pressure is lower than the normal value for a long time, or there are phenomena such as ground grouting and surrounding pile hole grouting and the like, the interval grouting can be used, and the interval time should be 30-60 minutes; alternatively, the water cement ratio can be lowered, the grouting flow rate can be reduced, or the admixtures such as accelerators can be added. If all pressure-grouting pipes 1 at the pile end cannot be opened, the pipe bottom of the measuring tube 2 can be drilled to the bearing layer, or the core hole at the pile end can be used as a grouting supplement channel. At this time, the grouting amount can be taken as the design value; it is also possible to drill a hole 30 cm outside the pile to 20 cm below the pile end elevation and rebury the pressure-grouting pipe 1 for grouting supplement. The grouting amount should be 120% of the design value.

Claims

1. A distributed pressure-grouting device for a bridge approach pile foundation, characterized in that, the distributed pressure-grouting device for a bridge approach pile foundation comprises a pressure-grouting pipe, a grout outlet valve and a grout stop valve,a plurality of pressure-grouting pipes are correspondingly distributed on an inner side of reinforcing cage, and are uniformly distributed around a circumferential direction of the reinforcing cage,a plurality of grout outlet valves are uniformly distributed on the pressure-grouting pipe, and are extended radially to an outer circumferential surface of the reinforcing cage,the grout stop valve is correspondingly provided inside the pressure-grouting pipe, and is slidably assembled along an axial direction of the pressure-grouting pipe,the grout stop valve comprises a grouting pipe and a pressure-charging pipe, wherein one end of the grouting pipe is connected to a grouting pump by means of a grout supply pipe, and the other end of the grouting pipe is a closed end; the middle of the grouting pipe is provided with a grout outlet; and two ends of the grouting pipe are respectively sleeved with balloons, the balloons positioned at the two ends of thegrouting pipe are connected in series by means of the pressure-charging pipe, and two sides of one of the grout outlet valves are sealed by two balloons respectively, so that a grouting channel is formed by the grouting pipe, the grout outlet and corresponding grout outlet valve.

2. The distributed pressure-grouting device for a bridge approach pile foundation according to claim 1, characterized in that, the balloons are cylindrical structure, and two ends of the balloons are fixed to the grouting pipe through an end plate respectively, and adjacent end plates of two balloons are communicated through the pressure-charging pipe, and a balloon which is far away from the closed end of the grouting pipe is correspondingly connected to an air pump through a gas supply pipe.

3. The distributed pressure-grouting device for a bridge approach pile foundation according to claim 2, characterized in that, the grout supply pipe and the gas supply pipe are integrally formed, or are connected as a whole by bonding.

4. The distributed pressure-grouting device for a bridge approach pile foundation according to claim 1, characterized in that, the grout outlet valve is a three-way pipe which is correspondingly connected to the pressure-grouting pipe, and one pipeline of the three-way pipe is extended radially along the reinforcing cage, a middle pipeline end of the three-way pipe is provided with a backstop, and the backstop is an elastic sleeve which is correspondingly sleeved on the middle pipeline end.

5. The distributed pressure-grouting device for a bridge approach pile foundation according to claim 1, characterized in that, the closed end of the grouting pipe is sealed in a detachable manner through a plunger.

6. The distributed pressure-grouting device for a bridge approach pile foundation according to claim 1, characterized in that, a lower end of the pressure-grouting pipeis a sharp sealing end, and the lower end of the pressure-grouting pipe is inserted into a bottom portion of pile hole, a part of side portion where the pressure-grouting pipe is inserted into the bottom portion of the pile hole is provided with a pressure-grouting port, and the pressure-grouting pipe is sleeved with a rubber sleeve which is corresponded to the pressure-grouting port.

7. A distributed pressure-grouting method for a bridge approach pile foundation, which uses the distributed pressure-grouting device for a bridge approach pile foundation according to any one of claims 1-6 for pressure-grouting, characterized in that, the distributed pressure-grouting method for a bridge approach pile foundation comprises:Step SI, synchronously binding the pressure-grouting pipe and the grout outlet valve during reinforcing cage processing;Step S2, placing the reinforcing cage to the bottom portion of the pile hole after the bottom portion is cleaned, and pouring concrete into the pile hole;Step S3, placing the grout stop valve into one of the pressure-grouting pipes, so that the grout outlet in a middle of the grout stop valve is faced to the lowest grout outlet valve of the pressure-grouting pipes;Step S4, supplying gas to two balloons, sealing two sides of the corresponding grout outlet valve after the two balloons are swelled, and supplying grout into the grouting pipe to form the grouting channel with the grouting pipe, the grout outlet and the corresponding grout outlet valve, so as to inject the grout into an outer circumference of the pile hole; andStep S5, injecting the grout into the grout outlet valve successively from bottom to top, and after grouting operations of all grout outlet valves in one of the pressure-grouting pipes are completed, performing the grouting of next pressure-grouting pipe until the grouting of all pressure-grouting pipes are completed.

8. The distributed pressure-grouting method for a bridge approach pile foundationaccording to claim 7, characterized in that, in the step S3, the grout outlet valve is opened within 24 hours of concrete pouring, during opening, clear water is sequentially injected into the grout outlet valves through the grout stop valve, and water injection is stopped after the water pressure drops, and the opening is completed.

9. The distributed pressure-grouting method for a bridge approach pile foundation according to claim 7, characterized in that, after concrete of pile body reaches 85% of design strength, an integrity of the pile body is tested by a measuring tube, and pressure-grouting amount corresponded to each grout outlet valve is set based on test result.

10. The distributed pressure-grouting method for a bridge approach pile foundation according to claim 9, characterized in that, during pressure-grouting, if the pressuregrouting amount of one of the grout outlet valves in the pressure-grouting pipe does not meet set requirement, the pressure-grouting amount that has not been injected should be injected by the grout outlet valve on an upper side or lower side of the grout outlet valve.

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