An improved lateral soil pressure gas cap method test device and use method

Abstract

The present invention discloses an improved lateral earth pressure gas cap method testing device and a method for using the device, the device comprises a bracket fixed inside the underground continuous wall; a gas cap unit installed on the bracket; an earth pressure box installed on the gas cap unit, the gas cap unit can push out the earth pressure box to measure the lateral earth pressure of the soil body; and an air cap pressure control unit connected to the gas cap unit, the gas cap pressure control unit can control the size of the ejection air pressure of the gas cap unit. The present invention can apply different ejection air pressures to earth pressure boxes at different depths, thereby avoiding the disadvantages of over-top and under-top, making the earth pressure box close to the soil body, and improving the buried survival rate of the sensor in the earth pressure box. At the same time, by fixing the bracket inside the soil body and installing the gas cap unit on the bracket, it is ensured that the ejection direction of the earth pressure box is fixed when the gas cap unit is pressurized, so that the measurement data is more accurate.

Description

Technical Field

[0001] The invention relates to the technical field of foundation pit engineering monitoring, and in particular to an improved lateral soil pressure air cap method testing device and a use method thereof. Background Art

[0002] With the rapid development of underground space development, the excavation depth of foundation pit projects is getting deeper and deeper, and the depth of underground continuous walls is also getting deeper and deeper. Large earth pressure is generated on both sides of the ground-connected walls, which often leads to deformation, cracking and even collapse of the ground-connected walls. Therefore, it is very important to accurately grasp the earth pressure on the outside of the ground-connected walls.

[0003] The earth pressure box is a common device used to test earth pressure. It monitors the earth pressure at a certain part of the soil through frequency testing. Common methods for burying earth pressure boxes include: hanging cloth method, drilling method, and ejection method. Among them, the hanging cloth method makes it difficult to control the burial position and direction of the earth pressure box. Concrete slurry is easily mixed between the earth pressure box and the soil behind the wall, causing the earth pressure box to be wrapped in cement and scrapped; the drilling method will cause stress redistribution of the original soil, and the steel cage has a larger stiffness than the soil. After being buried in the soil, there is a problem of incoordination with the lateral deformation of the soil; in comparison, the earth pressure box buried by the ejection method has a higher test accuracy, but the equipment and components are easily damaged during the burial process, and the traditional ejection method directly uses a gas pressure value for ejection, which may cause over-elevation or under-elevation. Summary of the invention

[0004] Based on this, it is necessary to provide an improved lateral soil pressure air cap method testing device and a method of use with high burial survival rate and high measurement data accuracy in order to address the above technical problems.

[0005] An improved lateral earth pressure gas cap method testing device, comprising:

[0006] A bracket fixed inside the underground continuous wall;

[0007] A gas cap unit, mounted on the bracket;

[0008] An earth pressure box is installed on the gas cap unit, and the gas cap unit can push out the earth pressure box to measure the lateral earth pressure of the soil body;

[0009] A gas cap pressure control unit is connected to the gas cap unit, and the gas cap pressure control unit can control the ejection air pressure of the gas cap unit.

[0010] In one embodiment, the bracket includes a connecting panel and a bracket plate, main reinforcement is provided inside the underground continuous wall, one side of the connecting panel is fixed on the main reinforcement, the bracket plate is arranged on the other side of the connecting panel, and the air cap unit is installed on the bracket plate.

[0011] In one of the embodiments, the air cap unit includes an air inlet and an air outlet, wherein the air inlet and the air outlet are respectively connected to one end of an air inlet pipe and an air outlet pipe, and the air inlet pipe is connected to the air cap pressure control unit.

[0012] In one embodiment, the air cap pressure control unit includes an air pump, an air storage tank and an air pipe control valve, the air pump is connected to the inlet of the air storage tank, the outlet of the air storage tank is connected to the air inlet pipe, and the air pipe control valve is installed on the air inlet pipe and the air outlet pipe.

[0013] In one of the embodiments, the earth pressure cell is connected to a frequency meter.

[0014] A method for using an improved lateral earth pressure gas cap method comprises the following steps:

[0015] The improved lateral earth pressure gas cap method test device is fixed at each set depth of the underground continuous wall;

[0016] Calculate the theoretical frequency corresponding to the static earth pressure of each earth pressure box at different depths;

[0017] The earth pressure boxes are pressurized in stages until each earth pressure box is pushed out to a theoretical frequency.

[0018] In one embodiment, the step of calculating the theoretical frequency corresponding to the static earth pressure of each earth pressure box at different depths includes:

[0019] a. Calculate the static earth pressure P0 of each earth pressure box at different depths:

[0020] P0=K0·∑γ i h i

[0021] Where K0 is the lateral pressure coefficient; γ i is the natural bulk density of the overlying soil layer; h i is the thickness of the overlying soil layer;

[0022] b. Calculate the pressure value P1 of the earth pressure box after the ground-connected wall reinforcement cage is hoisted into place:

[0023] P1=k*(f1 2 -f0 2 )

[0024] Where K is the calibration coefficient of the earth pressure box; f1 is the instantaneous frequency value of the earth pressure box; f0 is the frequency value after the earth pressure box is installed;

[0025] c. Calculate the theoretical ejection pressure P 气 :

[0026] P 气 =(P0-P1)*(d2 / d1) 2

[0027] Where, P0 is the static earth pressure of the earth pressure box; P1 is the pressure value of the earth pressure box after the ground-anchored wall reinforcement cage is hoisted into place; d1 is the piston radius of the air cap unit; d2 is the radius of the earth pressure box;

[0028] d. Calculate the theoretical frequency f corresponding to the static earth pressure 理 :

[0029] P0=k*(f 理 2 -f0 2 )

[0030] Where P0 is the static earth pressure of the earth pressure box; k is the calibration coefficient of the earth pressure box; f0 is the frequency value after the earth pressure box is installed.

[0031] In one embodiment, the step of pressurizing each of the earth pressure boxes in stages until each of the earth pressure boxes is pushed out to a theoretical frequency comprises:

[0032] First, use an air pump to pressurize the gas storage tank to reach the set pressure range;

[0033] Open the air pipe control valve of the air inlet pipe, pressurize the air top unit, and first apply the theoretical ejection pressure P 气 When the pressure is between 70% and 80% and it cannot be pushed out, gradually increase the pressure by 5% until it reaches 100%;

[0034] If it has not been ejected, increase the air pressure by 5%-10% each step until the earth pressure box is ejected to the theoretical frequency f corresponding to the static earth pressure. 理 .

[0035] In one embodiment, the set pressure range of the gas storage tank is: 0.5-0.8 times the theoretical calculated pressure value of the gas storage tank.

[0036] In one of the embodiments, during the pressurization of the gas cap unit, the frequency of the frequency meter is read in real time.

[0037] The improved lateral soil pressure gas cap method test device and use method control the ejection air pressure of the gas cap unit through the gas cap pressure control unit to achieve graded pressurization, which can apply different ejection air pressures to soil pressure boxes at different depths, thereby avoiding the shortcomings of over-top and under-top, making the soil pressure box close to the soil body, and improving the buried survival rate of the sensor in the soil pressure box. At the same time, by fixing the bracket inside the soil body and installing the gas cap unit on the bracket, it is ensured that the ejection direction of the soil pressure box is fixed when the gas cap unit is pressurized, so that the measurement data is more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a usage state diagram of the improved lateral earth pressure gas cap method testing device of the present invention;

[0039] Figure 2 It is a partial structural schematic diagram of the improved lateral earth pressure air cap method testing device of the present invention;

[0040] Figure 3 It is a flow chart of pressurization control of the method of the improved lateral earth pressure gas cap method testing device of the present invention. DETAILED DESCRIPTION

[0041] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. Preferred embodiments of the present invention are provided in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0042] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only implementation method.

[0043] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0044] See also Figure 1-2As shown, an embodiment of the present invention provides an improved lateral soil pressure gas cap method testing device, including a bracket 1, a gas cap unit 2, a soil pressure box 3 and a gas cap pressure control unit 4.

[0045] In one embodiment, the bracket 1 is fixed inside the underground continuous wall; the bracket 1 includes a connecting panel 11 and a bracket plate 12, the underground continuous wall is provided with a main reinforcement 5 inside, one side of the connecting panel 11 is fixed on the main reinforcement 5, the bracket plate 12 is arranged on the other side of the connecting panel 11, and the air cap unit 2 is installed on the bracket plate 12.

[0046] Specifically, the connection panel 11 can be a steel plate, etc., and the connection panel 11 is fully welded to the main reinforcement 5 at a set depth, and a certain verticality is ensured, so that the firmness of the connection can be improved, and the ejection direction of the earth pressure box 3 can be auxiliaryly fixed. Optionally, the bracket plate 12 can be an L-shaped steel plate, and the bracket plate 12 is connected to the head and tail parts of the connection panel 11, and the connection method can be welding, screwing, etc.

[0047] Further, the gas cap unit 2 is mounted on the support 1, for example, the two ends of the gas cap unit 2 are respectively fixed on the support plate 12 at the head and tail parts of the connection panel 11. In this embodiment, the gas cap unit 2 can be a cylinder, and a level ruler can be used to detect and correct the verticality and horizontality of the gas cap unit 2 to ensure that the gas ejection direction is consistent with the measured soil pressure direction, so that the soil pressure box 3 is in full contact with the soil body, and the measurement accuracy is improved. In one embodiment of the present invention, the gas cap unit 2 includes an air inlet 22 and an air outlet 21, and the air inlet 22 and the air outlet 21 are respectively connected to one end of the air inlet pipe 8 and the air outlet pipe 7, and the air inlet pipe 8 is connected to the gas cap pressure control unit 4. When the air outlet pipes 7 on different gas cap units 2 at the same depth can be connected in series through a connection device such as a three-way valve and a four-way valve, they can be merged to form an air outlet pipe, so that the number of air pipes and the workload of arranging air pipes on site can be reduced.

[0048] Further, the earth pressure box 3 is installed on the gas cap unit 2, that is, the end of the ejector rod of the gas cap unit 2 is connected to the earth pressure box 3. Optionally, the earth pressure box 3 is connected and fixed to the gas cap unit 2 by setting a connection unit; the gas cap unit 2 can eject the earth pressure box 3 to measure the lateral earth pressure of the underground continuous wall; wherein, the earth pressure box 3 is connected to the frequency meter 6. The frequency meter 6 can detect the instantaneous frequency value of the earth pressure box 3.

[0049] Furthermore, a gas cap pressure control unit 4 is connected to the gas cap unit 2 , and the gas cap pressure control unit 4 can control the ejection air pressure of the gas cap unit 2 .

[0050] The improved lateral earth pressure gas cap method test device and use method control the ejection air pressure of the gas cap unit 2 through the gas cap pressure control unit 4 to achieve graded pressurization, which can apply different ejection air pressures to the earth pressure box 3 at different depths, thereby avoiding the shortcomings of over-top and under-top, making the earth pressure box 3 close to the soil, and improving the buried survival rate of the sensor in the earth pressure box 3. At the same time, by fixing the bracket 1 inside the underground continuous wall and installing the gas cap unit 2 on the bracket 1 using the bracket plate 12, it is ensured that the ejection direction of the earth pressure box 2 is fixed when the gas cap unit 2 is pressurized, so that the measurement data is more accurate.

[0051] In one embodiment of the present invention, the air top pressure control unit 4 includes an air pump 41, an air tank 42 and an air pipe control valve 43, the air pump 41 is connected to the inlet of the air tank 42, the outlet of the air tank 42 is connected to the air inlet pipe 8, and the air pipe control valve 43 is installed on the air inlet pipe 8 and the air outlet pipe 7. In this embodiment, the output air pressure of the air tank 42 can be adjusted by flexibly adjusting the air pipe control valve 43, so as to achieve precise pressure control during the ejection process of the soil pressure box 3.

[0052] It should be noted that the cables of the earth pressure box 3 are gathered together with the air inlet pipe 8 and the air outlet pipe 7 and are arranged upward along the vertical main reinforcement 5 and fixed to the ground. It is necessary to ensure flatness, reduce the redundancy of unattached air pipes, prevent the air pipes from bending and breaking, and avoid failure of ejection of the earth pressure box 3. In addition, the position of the connection panel 11 should avoid the concrete pouring bin and the cross scissors support and other parts to prevent the cables, air inlet pipe 8 and air outlet pipe 7 of the earth pressure box 3 from being damaged during the concrete pouring and scissors support cutting process. In addition, when arranging the cables of the earth pressure box 3, a certain length of ejection cable should be reserved at the ejection end of the gas cap unit 2, and the reserved length of the cable should not be less than the maximum ejection length of the gas cap unit 2.

[0053] See also Figure 3 As shown, a method for using an improved lateral earth pressure gas cap method comprises the following steps:

[0054] S1. Fix the above-mentioned improved lateral earth pressure air cap method test device at each set depth of the underground continuous wall;

[0055] S2, calculating the theoretical frequency corresponding to the static earth pressure of each earth pressure box 3 at different depths;

[0056] S3, pressurizing each of the earth pressure boxes 3 in stages until each of the earth pressure boxes 3 is pushed out to a theoretical frequency.

[0057] In one embodiment of the present invention, the steps of fixing the improved lateral earth pressure gas cap method testing device at each set depth of the underground continuous wall include:

[0058] S11. Use the bracket plate 12 to install and fix the air cap unit 2 and the earth pressure box 3 on the ground-connected wall steel cage in sequence according to the designed depth position. After installation, the frequency value of the earth pressure box 3 after installation, as well as the installation position and depth of the corresponding numbered earth pressure box 3, should be tested and recorded respectively;

[0059] S12. Arrange the cables, air inlet pipe 8 and air outlet pipe 7 of the earth pressure box 3; specifically, securely connect the air inlet pipe 8 and air outlet pipe 7 to the air inlet port 22 and air outlet port 21 of the air cap unit 2, respectively; gather the cables, air inlet pipe 8 and air outlet pipe 7 of the earth pressure box 3 and arrange them upward along the vertical main reinforcement 5, and tie and fix them to the vertical main reinforcement 5 with plastic ties or iron wires every 2 to 3 meters; the cables, air inlet pipe 8 and air outlet pipe 7 facing the pit surface should be arranged upward together along the vertical main reinforcement 5 facing the soil surface.

[0060] S13, hoisting the ground-connected wall reinforcement cage; specifically, after the earth pressure box 3 is installed, before the reinforcement cage is hoisted, if conditions permit, a simulated ejection test should be carried out to check the air tightness of the air inlet pipe 8 and the air outlet pipe 7 and the reliability of the air cap unit 2; before hoisting the ground-connected wall reinforcement cage, the air pipe control valves 43 of all air outlet pipes 7 should be closed to prevent the ejection rod of the air cap unit 2 from sliding freely together with the earth pressure box 3 during the hoisting of the reinforcement cage; finally, the ground-connected wall reinforcement cage is hoisted.

[0061] In one embodiment of the present invention, the step of calculating the theoretical frequency corresponding to the static earth pressure of each earth pressure cell 3 at different depths comprises:

[0062] a. Calculate the static earth pressure P0 of each earth pressure box at different depths:

[0063] P0=K0·∑γ i h i

[0064] Where K0 is the lateral pressure coefficient; γ i is the natural bulk density of the overlying soil layer; h i is the thickness of the overlying soil layer;

[0065] b. Calculate the pressure value P1 of the earth pressure box after the ground-connected wall reinforcement cage is hoisted into place:

[0066] P1=k*(f1 2 -f0 2 )

[0067] Where K is the calibration coefficient of the earth pressure box; f1 is the instantaneous frequency value of the earth pressure box; f0 is the frequency value after the earth pressure box is installed;

[0068] c. Calculate the theoretical ejection pressure P 气 :

[0069] P气 =(P0-P1)*(d2 / d1) 2

[0070] Where, P0 is the static earth pressure of the earth pressure box; P1 is the pressure value of the earth pressure box after the ground-anchored wall reinforcement cage is hoisted into place; d1 is the piston radius of the air cap unit; d2 is the radius of the earth pressure box;

[0071] d. Calculate the theoretical frequency f corresponding to the static earth pressure 理 :

[0072] P0=k*(f 理 2 -f0 2 )

[0073] Where P0 is the static earth pressure of the earth pressure box; k is the calibration coefficient of the earth pressure box; f0 is the frequency value after the earth pressure box is installed.

[0074] In one embodiment of the present invention, the step of pressurizing each of the earth pressure boxes 3 in stages until each of the earth pressure boxes 3 is pushed out to a theoretical frequency comprises:

[0075] First, the air pump 41 is used to pressurize the air storage tank 42 to reach the set pressure range; the air pipe control valve 43 of the air inlet pipe 8 is opened to pressurize the air top unit 2, and the theoretical ejection pressure P is first applied. 气 If the pressure is still not ejected, increase the pressure by 5% step by step until it reaches 100%; if it is still not ejected, increase the pressure by 5%-10% step by step until the earth pressure box 3 is ejected to the theoretical frequency f corresponding to the static earth pressure. 理 That is, the burial of the earth pressure box 3 at the corresponding design depth is completed.

[0076] In this embodiment, the set pressure range of the gas tank is: 0.5-0.8 times the theoretical calculated pressure value of the gas tank. Optionally, during the pressurization of the gas cap unit 2, the frequency of the frequency meter 6 is read in real time to facilitate the subsequent calculation of the theoretical frequency of the earth pressure box 3.

[0077] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0078] The above-described embodiments only express several implementation methods of the present application, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present application, which all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the attached claims.

Claims

1. The improved method of using the lateral earth pressure gas cap method is characterized by: The following steps are involved: An improved lateral earth pressure gas cap method test device is fixed at each set depth of the soil body. The test device includes: A bracket, fixed to the inside of the underground continuous wall; A gas cap unit, mounted on the bracket; An earth pressure box is installed on the gas cap unit, and the gas cap unit can push out the earth pressure box to measure the lateral earth pressure of the soil body; A gas cap pressure control unit is connected to the gas cap unit, and the gas cap pressure control unit can control the ejection gas pressure of the gas cap unit; The bracket includes a connecting panel and a bracket plate, a main rib is provided inside the underground continuous wall, one side of the connecting panel is fixed on the main rib, the bracket plate is arranged on the other side of the connecting panel, and the gas cap unit is mounted on the bracket plate; The steps of calculating the theoretical frequency corresponding to the static earth pressure of each earth pressure box at different depths include: a. Calculate the static earth pressure P0 of each earth pressure box at different depths: P0=K0·∑γ i h i Where K0 is the lateral pressure coefficient; γ i is the natural bulk density of the overlying soil layer; h i is the thickness of the overlying soil layer; b. Calculate the pressure value P1 of the earth pressure box after the ground-connected wall reinforcement cage is hoisted into place: P1=k*(f1 2 -f0 2 ) Where K is the calibration coefficient of the earth pressure box; f1 is the instantaneous frequency value of the earth pressure box; f0 is the frequency value after the earth pressure box is installed; c. Calculate the theoretical ejection pressure P 气 : P 气 =(P0-P1)*(d2 / d1) 2 Where, P0 is the static earth pressure of the earth pressure box; P1 is the pressure value of the earth pressure box after the ground-anchored wall reinforcement cage is hoisted into place; d1 is the piston radius of the air cap unit; d2 is the radius of the earth pressure box; d. Calculate the theoretical frequency f corresponding to the static earth pressure 理 : P0=k*(f 理 2 -f0 2 ) Where, P0 is the static earth pressure of the earth pressure box; k is the calibration coefficient of the earth pressure box; f0 is the frequency value after the earth pressure box is installed; The steps of pressurizing each of the earth pressure boxes in stages until each of the earth pressure boxes is pushed out to a theoretical frequency include: First, use an air pump to pressurize the gas storage tank to reach the set pressure range; Open the air pipe control valve of the air inlet pipe, pressurize the air top unit, and first apply the theoretical ejection pressure P 气 70%-80% of the air pressure. If it cannot be pushed out, gradually increase by 5% until it reaches 100% of the air pressure. If it has not been pushed out, increase the air pressure by 5%-10% each step until the earth pressure box is pushed out to the theoretical frequency f corresponding to the static earth pressure. 理 .

2. The method for using the improved lateral earth pressure gas capping method as claimed in claim 1, characterized in that: The air cap unit includes an air inlet and an air outlet, wherein the air inlet and the air outlet are respectively connected to one end of an air inlet pipe and an air outlet pipe, and the air inlet pipe is connected to the air cap pressure control unit.

3. The method for using the improved lateral earth pressure gas capping method as claimed in claim 2, characterized in that: The air cap pressure control unit includes an air pump, an air storage tank and an air pipe control valve, the air pump is connected to the inlet of the air storage tank, the outlet of the air storage tank is connected to the air inlet pipe, and the air pipe control valve is installed on the air inlet pipe and the air outlet pipe.

4. The method for using the improved lateral earth pressure gas capping method as claimed in claim 3, characterized in that: The earth pressure box is connected to a frequency meter.

5. The method for using the improved lateral earth pressure gas capping method as claimed in claim 4, characterized in that: The set pressure range of the gas storage tank is: 0.5-0.8 times the theoretical calculated pressure value of the gas storage tank.

6. The method for using the improved lateral earth pressure gas capping method as claimed in claim 5, characterized in that: During the pressurization of the gas cap unit, the frequency of the frequency meter is read in real time.

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