CN105386473A - Method for detecting pile foundation post grouting quality based on multi-point ejection type sensor measurement technology - Google Patents

Abstract

The present invention discloses a method for detecting the post-grouting quality of pile foundation based on multi-point ejection sensor measurement technology, comprising: (1) installing a sensor: fixing a sensor with a hydraulic cylinder or a pneumatic cylinder on the main reinforcement of a steel cage, and connecting the acquisition signal input end of an external data acquisition instrument to the output end of the sensor; a plurality of sensors are arranged upward along the bottom of the steel cage; (2) fixing and installing the steel cage in a pile hole of a pre-dug cast-in-place pile; (3) after the steel cage is placed in place, ejecting the sensor by a hydraulic cylinder or a pneumatic cylinder, and the ejected sensor contacts the hole wall of the cast-in-place pile; (4) pouring concrete into the pile hole of the cast-in-place pile; (5) reading the values measured by the sensor at each depth before grouting by a data acquisition instrument; (6) grouting; (6) after the grouting is completed, reading the values measured by the sensor at each depth after grouting by the data acquisition instrument; the distribution state of the slurry in the soil on the pile side can be obtained by comparing the values before and after grouting.

Description

A method for detecting the quality of grouting after pile foundation based on multi-point ejection sensor measurement technology

technical field

The invention relates to a method for detecting the grouting quality of a pile foundation based on a multi-point ejection sensor measurement technology, which belongs to the field of bridge pile foundation detection.

Background technique

The post-pile grouting technology can effectively reduce the pile length, improve the bearing capacity of cast-in-place piles, With the advantages of reducing pile settlement, shortening the construction period, and reducing the engineering cost of cast-in-situ piles, the post-pile grouting technology has obvious advantages and good application prospects. In recent years, it has been widely used in transportation, construction, water conservancy and other fields.

However, since the pile foundation is a concealed project, it is difficult to judge the quality of the grouting construction after the pile foundation, and the geological conditions are changeable and complex. Finally, it is very difficult to evaluate the specific grouting effect. Up to now, it is mainly through measuring the ultimate bearing capacity of a single pile to evaluate whether the pile meets the design requirements. This method can only randomly select a part for representative testing, and cannot be applied to large quantities of piles. The evaluation of grouting effect can not directly evaluate the effect of grouting, but can only indirectly reflect the effect of grouting. Among the existing detection methods, there is no good quality detection method for the reinforcement effect of the grout at the bottom of the pile body and the soil around the pile.

Contents of the invention

In order to overcome the above-mentioned shortcomings of the existing detection method for the reinforcement effect of grout in the bottom of the pile body and the soil around the pile, the present invention provides a method for detecting the quality of grouting after pile foundation based on multi-point ejection sensor measurement technology, This method adopts the multi-point pressure sensor measurement technology and the design method of the hydraulic or pneumatic ejection device to detect the grouting effect of the post-pile grouting technology and the distribution of the grout in the soil, so as to evaluate the pile. The post-foundation grouting effect provides detection data; in addition, according to the construction characteristics of the pile foundation, the hydraulic or pneumatic ejection device design method is used to greatly improve the contact effect between the sensor and the hole wall, thereby improving the measurement accuracy and accuracy.

The technical scheme adopted in the present invention is:

The method for detecting post-pile grouting quality based on multi-point ejection sensor measurement technology is characterized in that it includes the following steps:

(1), install the sensor: fix the sensor with the hydraulic cylinder or the pneumatic cylinder on the main reinforcement of the steel cage, the sensor is fixedly connected with the piston rod of the hydraulic cylinder or the pneumatic cylinder, and the acquisition signal input terminal of the external acquisition instrument is connected The output end of the sensor; multiple sensors are arranged upwards along the bottom of the steel cage, the distance between adjacent sensors is 50cm to 100cm, and the arrangement of sensors from bottom to top is from dense to sparse; measuring cables, hydraulic pipes or pneumatic pipes pass through The steel wire is bound next to the main reinforcement;

(2), install reinforcement cage: fixedly install reinforcement cage in the pile hole of pre-excavated cast-in-situ pile, described reinforcement cage comprises the main reinforcement that is arranged vertically and is arranged in a ring and is welded on the described main reinforcement horizontally Multiple hoop stirrups;

(3) Ejection of the sensor: After the steel cage is placed in place, the sensor is ejected by a hydraulic cylinder or a pneumatic cylinder, and the sensor after the ejection is in contact with the hole wall of the cast-in-place pile;

(4) Concrete is poured into the pile hole of the cast-in-place pile;

(5) After the concrete reaches 70% or more of the design strength, use the collector to read the values measured by the sensors of each depth before grouting;

(6), grouting;

(6) After grouting is completed, after maintenance and reinforcement, use the collector to read the values measured by sensors at various depths after grouting; the distribution state of grout in the pile side soil can be obtained by comparing the values before and after grouting .

The sensor is a pressure sensor or a Ph sensor.

The hydraulic cylinder or pneumatic cylinder is fixed on the main rib through a fixed bracket.

In the present invention, post-pile grouting technology refers to that after the cast-in-situ pile is formed into a pile and reaches a certain strength, the high-pressure grouting pump will be able to play the role of cementation and curing through the pre-embedded grouting pipe around the pile or in the pile body. The grout is injected into the soil layer at the pile tip and the soil around the pile, so that the pile tip sediment, the pile tip bearing layer and the mud skin around the pile use the penetration, filling, compaction, splitting and consolidation of the slurry to change the original The physical properties and mechanical state of the soil can improve the strength of the pile tip soil and the pile side soil, increase the resistance of the pile tip and the friction force of the pile side to varying degrees, thereby reducing the settlement of the pile and improving the bearing capacity of the pile .

After the grouting of the pile foundation, after the grout is injected, the overall effect of the grouting is reflected by detecting the change of the pressure of the undisturbed soil and the mixed soil on the pile and the height of the pile body reached by the cement slurry. The pressure change value of the mixed soil on the pile body and the height of the grouting are tested by using the multi-point pressure sensor, which reflects the grouting effect of the grout.

For the range of grouting reinforcement after pile foundation, the detection content of grouting effect using multi-point pressure sensor measurement technology mainly includes:

1. The new multi-point sensor mainly uses its own conductive rubber. The elasticity of the conductive rubber is fixed on the vertical main rib through the fixed bracket. After the sensor is ejected, it uses the free elastic deformation of the rubber to make it fit naturally against the wall of the drilled pile. .

2. During the post-grouting process of the pile foundation, the muddy soil within a certain height above the pile tip and the soil around the muddy soil are reinforced within a certain width range, which in turn affects its pressure on the pile body and improves the pile side. Resistance, using multi-point pressure sensors can detect the distribution range of grout around the pile and the grouting height, so as to evaluate the improvement effect of grouting on pile side friction.

The beneficial effects of the present invention are reflected in:

1. Compared with the existing detection methods, the multi-point pressure sensor can accurately measure the pressure change of the excavated soil on the pile body, and can accurately measure the impact of the soil pressure on the pile after grouting without special devices. It can detect the grouting range in a large range on the pile side, and the detection efficiency is greatly improved.

2. The new multi-point pressure sensor is easy to install. It adopts the hydraulic ejection method or the design method of the cylinder ejection device. The device is simple and firm, and it is convenient for on-site construction.

Description of drawings

Fig. 1a is a schematic diagram of the multi-point pressure sensor of the present invention (before ejection).

Fig. 1b is a schematic diagram of the multi-point pressure sensor of the present invention (after ejection).

Fig. 2a is a schematic diagram before the sensor of the present invention is ejected.

Fig. 2b is a schematic diagram of the sensor of the present invention after ejection.

Fig. 3 is a cross-sectional view of the reinforcement cage of the present invention.

Fig. 4a is the A-A sectional view of Fig. 3 .

Fig. 4b is a B-B sectional view of Fig. 3 .

Fig. 5 is a schematic diagram of the technical implementation process of the present invention.

detailed description

Referring to Figures 1a to 5, the method for detecting the quality of grouting after pile foundation based on multi-point ejection sensor measurement technology includes the following steps:

(1), sensor installation: the sensor 1 with hydraulic cylinder or pneumatic cylinder 2 is fixed on the main bar 51 of reinforcement cage 5, and described sensor 1 is fixedly connected with the piston rod 21 of hydraulic cylinder or pneumatic cylinder, and the external acquisition instrument The input terminal of the acquisition signal of 7 is connected to the output terminal of the sensor 1; multiple sensors 1 are arranged upward along the bottom of the steel cage 5, and the distance between adjacent sensors 1 is 50cm to 100cm, and the arrangement of the sensors from bottom to top is from dense to sparse. ;Measuring cables, hydraulic pipes or air pressure pipes 4 are bound to the main reinforcement by steel wires;

(2), install reinforcement cage: in the pile hole of pre-excavated cast-in-place pile, fix installation reinforcement cage 5, described reinforcement cage 5 comprises the main reinforcement 51 that is arranged in a ring by many vertical settings and the horizontal interval welded in place A plurality of hoop stirrups 52 on the main reinforcement;

(3) Ejection of the sensor: After the reinforcement cage 5 is placed in place, the sensor 1 is ejected by the hydraulic cylinder or the pneumatic cylinder 2, and the sensor 1 after the ejection is in contact with the hole wall 6 of the cast-in-place pile;

(4) Concrete is poured into the pile hole of the cast-in-place pile;

(5), after concrete reaches 70% of design strength or more, utilize acquisition instrument 7 to read the numerical value that the sensor of each depth before grouting measures;

(6), grouting;

(6), after the grouting is completed, after maintenance and reinforcement, use the acquisition instrument 7 to read the values measured by the sensors of each depth after the grouting; the distribution of the grout in the pile side soil can be obtained by comparing the values before and after the grouting state.

The sensor 1 is a pressure sensor or a Ph sensor.

The hydraulic cylinder or pneumatic cylinder 2 is fixed on the main rib 51 through the fixing bracket 3 .

In this embodiment, after the grout is injected into the pile foundation, the overall effect of the grouting can be reflected by detecting the change of the pressure of the undisturbed soil and the mixed soil on the pile body and the height of the pile body reached by the cement slurry. The pressure change value of the mixed soil on the pile body and the height of the grouting are tested by using the multi-point pressure sensor, which reflects the grouting effect of the grout.

The post-grouting test of the pile foundation adopts the multi-point pressure sensor measurement technology, and the design method of the hydraulic or pneumatic ejection device is used to directly test the grouting effect before and after the pile foundation grouting.

1. When tying the reinforcement cage, fix the multi-point pressure sensor (or cement slurry ph sensor, or pressure sensor) with hydraulic jack (with cylinder) on the main reinforcement, and connect the fixed bracket to the main reinforcement. Measuring cables, hydraulic pipes or pneumatic pipes are bound next to the main reinforcement by steel wires. Multi-point pressure sensors are arranged from the bottom of the steel cage upwards, and the spacing of the sensors from the bottom to the top is from dense to sparse, and the spacing is from 50cm to 100cm. The height or number of sensors is arranged according to the pile length, geological data and related design requirements. set up.

2. After the reinforcement cage is placed in place, use hydraulic pressure (or air pressure) to push out the new multi-point sensor to make contact with the hole wall, and then pour concrete into the bored pile.

3. After the concrete reaches 70% or more of the design strength, use a special collector to test the soil pressure at each depth before grouting (or test the ph value, or test the pressure) before grouting.

4. After the grouting has finished for a certain period of curing and reinforcement, use the same method to test the earth pressure at each depth after grouting. Thus, the distribution state of the grout in the pile side soil can be obtained.

In this embodiment, if the pressure becomes larger or the pH value increases, it means that the grouting is effective; the smaller the height of the reverse grouting is, that is, the better the grouting effect is.

Finally, it should be noted that what is listed above are only specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments, and many modifications are possible. All deformations that can be directly derived or associated by those skilled in the art from the content disclosed in the present invention should be considered as the protection scope of the present invention.

Claims (3)

1., based on the method for multiple spot ejecting type sensor measurement techniques detection of pier foundation post jacking quality, it is characterized in that: comprise the steps:

(1), sensor installation: the sensor of band hydraulic cylinder or pneumatic cylinder is fixed on the main muscle of reinforcing cage, described sensor is fixedly connected with the piston rod of hydraulic cylinder or pneumatic cylinder, the output of the collection signal sensor input connection of outside Acquisition Instrument; Multiple sensor is upwards arranged along the bottom of reinforcing cage, the spacing of adjacent sensors at 50cm ~ 100cm, and from the lower arrangement from upper sensor by close to dredging; Measuring cable, hydraulic tube or pneumatic tube is bundled in by main muscle by steel wire;

(2), install reinforcing cage: install reinforcing cage at the stake holes internal fixtion of the castinplace pile dug in advance, described reinforcing cage comprises by many vertical settings and the main muscle of circular array and horizontal interval are welded on the multiple hoop stirrups on described main muscle;

(3), the ejecting of sensor: after reinforcing cage is in place, utilize hydraulic cylinder or pneumatic cylinder to be ejected by sensor, the sensor after ejecting contacts with the hole wall of castinplace pile;

(4) toward concreting in the stake holes of castinplace pile;

(5), after concrete reach design strength 70% or more, the numerical value that before utilizing Acquisition Instrument to read slip casting, the sensor of each degree of depth records;

(6), slip casting;

(6), slip casting terminates, after maintenance is reinforced, and the numerical value that after recycling Acquisition Instrument reads slip casting, the sensor of each degree of depth records; The distribution of slurries in Pile side soil body can be obtained by the contrast of numerical value before and after slip casting.

2., as claimed in claim 1 based on the method for multiple spot ejecting type sensor measurement techniques detection of pier foundation post jacking quality, it is characterized in that: described sensor is pressure sensor or Ph sensor.

3., as claimed in claim 2 based on the method for multiple spot ejecting type sensor measurement techniques detection of pier foundation post jacking quality, it is characterized in that: described hydraulic cylinder or pneumatic cylinder are fixed on main muscle by fixed support.