CN101463598B - In situ calibrating device for soil pressure box and method therefor - Google Patents

Abstract

The invention discloses an original position calibrating device for a soil pressure cell and a method thereof, relating to the application technology of soil pressure cells. The device is structured as: in a round calibrating pit, a reinforced concrete floor (3), a soil pressure cell (1) covered by a rubber bag (5), medium and coarse sands (11), undisturbed soil (4), a rubber pad (10), a load steel plate (2), a jack (6) and a reaction frame (7) are arranged and connected in turn from bottom to top; the reaction frame(7) and a ground anchor(8) buried in the anchorage hole of the round calibrating pit are vertical to each other and connected by a coak (9). The method is mainly as follows: step one, the soil pressure cell (1) is connected with a steel string frequency tester to measure the initial reading of the soil pressure cell (1) under the condition of bearing no load; step two, the soil pressure cell (1) is positioned in the original position calibrating device for the soil pressure cell; step three, gradual loading is carried out and calibrating test is started; and step four, quantitative relation between the pressure input quantity and the frequency output quantity is calibrated. The device is applicable to the calibration of the soil pressure cell.

Description

Earth pressure cell original position caliberating device and method thereof

Technical field

The present invention relates to a kind of in civil engineering risk assessment and control the earth pressure cell application technology of monitoring during soil pressure, specifically, relate to a kind of earth pressure cell original position caliberating device and method thereof.

Background technology

In city underground station or the high-building construction, the place is narrow, and environment fringe conditions complexity is various.The outer undisturbed soil of safe mass, duration and cost, particularly foundation ditch that the excavation of deep foundation ditch directly influences whole engineering destroys the safe handling that causes surrounding building damage and various pipelines.The soil pressure of retaining structure and wall interface, hole different depth change be Construction Project Risk assessment and control must survey project, generally adopt earth pressure cell directly to measure.Yet, the data distortion that abominable site work environment often makes the earth pressure cell buried underground record, confidence level is difficult to guarantee, directly has influence on the accuracy of monitoring achievement and the differentiation and the evaluation of reliability.

Trace it to its cause, major influence factors also has the influence of environment except that having embedding effect, installation matching error, stress in burying underground to concentrate influence and the particle diameter effect, and promptly the calibration of Earth Pressure Cell problem is very important.

Earth pressure cell dispatch from the factory and use adopt air pressure to demarcate (gas mark) as last, liquid is demarcated (oil ga(u)ge) and native medium demarcation (sand mark); Its environment, temperature of demarcating environment and actual measuring point is inconsistent: indoor rating test often applies uniform pressure, and in its application, be subjected to the influence of shear action and arching distribution etc., cause actual soil pressure to produce bigger deviation than the soil pressure that indoor standardization calculates.

Therefore, it is very necessary to develop a kind of earth pressure cell original position caliberating device and method thereof.

Summary of the invention

Purpose of the present invention just is to overcome the shortcoming and defect that prior art exists, and a kind of earth pressure cell original position caliberating device and method thereof are provided.

The object of the present invention is achieved like this:

One, earth pressure cell original position caliberating device

Earth pressure cell original position caliberating device comprises earth pressure cell, is provided with to load steel plate, reinforced concrete floor, undisturbed soil, rubber bag, jack, reaction frame, earth anchor, latching, rubber pad, medium coarse sand, string wire frequency measurement instrument and leader cable;

Demarcating the on-the-spot table soil of removing, the circular hole of demarcating of excavation; Demarcate in the hole in circle, set gradually and be connected with reinforced concrete floor from top to bottom, put earth pressure cell, medium coarse sand, undisturbed soil, rubber pad, loading steel plate, jack and the reaction frame of rubber bag;

Reaction frame and the earth anchor of imbedding in the anchor hole of circular demarcation hole are orthogonal, connect by latching.

Two, earth pressure cell original position scaling method

Earth pressure cell original position scaling method comprises the following steps:

1. the leader cable with earth pressure cell connects string wire frequency measurement instrument, measures earth pressure cell at the initial reading that is not subjected under the loading condition;

2. earth pressure cell is placed earth pressure cell original position caliberating device;

3. load the beginning rating test step by step:

A, pressurization promptly add oil pressure to jack;

B, unloading promptly give the jack oil return to zero, keep 3min, read output frequency value;

C, loading are step by step promptly refueled to jack, and every grade of load is that 10kg loads step by step, and until reaching the rated pressure value, every stage pressure keeps 30s to read output frequency value at least;

4. calibrate the quantitative relation between pressure input quantity and the frequency output quantity.

The present invention has following advantage and good effect:

1. provided by the invention the hole in the on-the-spot underground excavation demarcation of engineering original position carried out rating test, guaranteed that the calibration of Earth Pressure Cell environment is similar to the earth pressure cell service condition, overcome the birth defects of methods such as traditional oil ga(u)ge, gas mark, sand mark, promptly environment temperature, embedding effect, installation matching error, stress are concentrated influence and particle diameter effect;

2. caliberating device provided by the invention and Qi Jia, unloading manner, actual condition and Load Transfer mode have been reflected, the frequency relation of guaranteeing the pressure imported and output is reliable, can obtain real soil pressure information parameter, thereby provides strong foundation for the deep foundation pit construction risk assessment.

3. the present invention is applicable to calibration of Earth Pressure Cell.

Description of drawings

Fig. 1 is this embedded device structure chart.

Wherein:

The 1-earth pressure cell; 2-loads steel plate; The 3-reinforced concrete floor;

4-undisturbed soil; The 5-rubber bag; The 6-jack;

The 7-reaction frame; The 8-earth anchor; The 9-latching;

The 10-rubber pad; The 11-medium coarse sand; 12-string wire frequency measurement instrument;

The 13-leader cable.

The specific embodiment

Describe in detail below in conjunction with drawings and Examples:

One, earth pressure cell original position caliberating device

Earth pressure cell original position caliberating device comprises earth pressure cell 1, is provided with to load steel plate 2, reinforced concrete floor 3, undisturbed soil 4, rubber bag 5, jack 6, reaction frame 7, earth anchor 8, latching 9, rubber pad 10, medium coarse sand 11, string wire frequency measurement instrument 12 and leader cable 13;

Demarcating the on-the-spot table soil of removing, the circular hole of demarcating of excavation; Demarcate in the hole in circle, set gradually from top to bottom and be connected with reinforced concrete floor 3, put rubber bag 5 earth pressure cell 1, medium coarse sand 11, undisturbed soil 4, rubber pad 10, load steel plate 2, jack 6 and reaction frame 7;

Reaction frame 7 and the earth anchor of imbedding in the anchor hole of circular demarcation hole 8 are orthogonal, connect by latching 9.

Two, earth pressure cell original position scaling method

As figure, earth pressure cell original position scaling method comprises the following steps:

1. remove table soil at engineering site, dig the circle of dark 1m, the about 1m of diameter and demarcate the hole, cheat all 60cm external application luoyang spades and dig out 8 of the anchor holes of dark 2m, and installation earth anchor 8, thick piece stone of mistake in the undisturbed soil 4 that rejecting is dug out or coarse gravel, be deposited on the limit standby, simultaneously, earth pressure cell 1 is connected string wire frequency measurement instrument 12 by leader cable 13, measure earth pressure cell 1 at the initial reading that is not subjected under the loading condition;

2. demarcate the thick C25 reinforced concrete floor 3 of bottom, hole pouring 10cm in circle, simulation retaining protection structure;

3. at the thick medium coarse sand 11 of reinforced concrete floor 3 upper berth one deck 2-4cm, the back-up sand that earth pressure cell 1 is buried underground is simulated in compacting;

4. place the earth pressure cell 1 that has put rubber bag 5 at medium coarse sand 11 centers, in the thick medium coarse sand 11 of rubber bag 5 top shop one deck 2-4cm, compacting;

5. insert undisturbed soil 4,, make real to from the about 20cm in earth pressure cell 1 top;

6. lay rubber pad 10 at undisturbed soil 4 tops, on rubber pad 10, place again and load steel plate 2;

7. loading placement jack 6 on the steel plate 2, adjust reaction frame 7 positions and planeness, by latching 9 assembling reaction frame 7 and earth anchors 8 according to its stroke;

8. give rubber bag 5 inflations, the transverse load of simulation bottom undisturbed soil 4; Jack 6 adds oil pressure, the simulation vertical load;

9. load the beginning rating test step by step:

A, pressurization (jack 6 adds oil pressure);

B, unloading (jack 6 oil returns keep 3min to zero, read output frequency value);

C, loading step by step (jack 6 refuels), every grade of load is that 10kg loads step by step, until reaching the rated pressure value, every stage pressure keeps 30s to read output frequency value at least;

10. experimental data and analysis calibrates the quantitative relation between pressure input quantity and the frequency output quantity.

Claims (2)

1. earth pressure cell original position caliberating device is characterized in that:

Earth pressure cell original position caliberating device comprises earth pressure cell (1), is provided with to load steel plate (2), reinforced concrete floor (3), undisturbed soil (4), rubber bag (5), jack (6), reaction frame (7), earth anchor (8), latching (9), rubber pad (10), medium coarse sand (11), string wire frequency measurement instrument (12) and leader cable (13);

Demarcate in the hole in circle, set gradually and be connected with reinforced concrete floor (3) from top to bottom, put rubber bag (5) earth pressure cell (1), medium coarse sand (11), undisturbed soil (4), rubber pad (10), load steel plate (2), jack (6) and reaction frame (7);

Reaction frame (7) and the earth anchor of imbedding in the anchor hole of circular demarcation hole (8) are orthogonal, connect by latching (9).

2. based on the scaling method of the described earth pressure cell original position of claim 1 caliberating device, it is characterized in that comprising the following steps:

1. remove table soil at engineering site, dig the circle of dark 1m, the about 1m of diameter and demarcate the hole, cheat all 60cm external application luoyang spades and dig out 8 of the anchor holes of dark 2m, and installation earth anchor (8), thick piece stone of mistake in the undisturbed soil that rejecting is dug out (4) or coarse gravel, be deposited on the limit standby, simultaneously, earth pressure cell (1) is connected string wire frequency measurement instrument (12) by leader cable (13), measure earth pressure cell (1) at the initial reading that is not subjected under the loading condition;

2. demarcate bottom, the hole pouring thick C25 reinforced concrete floor of 10cm (3) in circle, simulation retaining protection structure;

3. at reinforced concrete floor (3) the thick medium coarse sand of upper berth one deck 2-4cm (11), the back-up sand that earth pressure cell (1) is buried underground is simulated in compacting;

4. place the earth pressure cell (1) that has put rubber bag (5) at medium coarse sand (11) center, in shop, rubber bag (5) the top thick medium coarse sand of one deck 2-4cm (11), compacting;

5. insert undisturbed soil (4),, make real to from the about 20cm in earth pressure cell (1) top;

6. lay rubber pad (10) at undisturbed soil (4) top, go up at rubber pad (10) again and place loading steel plate (2);

7. loading upward placement jack (6) of steel plate (2), adjust reaction frame (7) position and planeness according to its stroke, by latching (9) assembling reaction frame (7) and earth anchor (8);

8. give rubber bag (5) inflation, the transverse load of simulation bottom undisturbed soil (4); Jack (6) adds oil pressure, the simulation vertical load;

9. load the beginning rating test step by step:

A, pressurization add oil pressure promptly for jack (6);

B, unloading promptly give jack (6) oil return to zero, keep 3min, read output frequency value;

C, loading step by step add oil pressure promptly for jack (6), and every grade of load is that 10kg loads step by step, and until reaching the rated pressure value, every stage pressure keeps 30s to read output frequency value at least;

10. experimental data and analysis calibrates the quantitative relation between pressure input quantity and the frequency output quantity.