Jacking Working Shaft Sinking Monitoring and Control System and Its Construction Method

Abstract

A jacking working well sinking monitoring and control system includes a monitoring system arranged on the steel reinforcement cage of the working well and a control system arranged outside the working well. The longitudinal main reinforcement in the middle of the steel reinforcement cage is truncated to form a fracture, and a reinforcing bar strain gauge is welded at the fracture of the longitudinal main reinforcement. A grouting pipe is welded between two adjacent layers of circumferential main reinforcements, and a soil pressure gauge base is arranged through the space between two layers of circumferential main reinforcements below the grouting pipe. A soil pressure gauge is installed on the soil pressure gauge base, and an inclination sensor and a collection box are installed on the inner wall of the working well. A grouting pipeline is connected to the grouting pipe, a hardened foundation is arranged around the outside of the working well, a jack support is arranged on the hardened foundation through high-strength bolts, and a hydraulic jack in the control system is installed on the jack support. The hydraulic jack is connected to a jack controller to achieve control. With the above structure, the present invention can view the sinking attitude and stress data of the open caisson in real time, and timely adjust the sinking attitude and the skin friction of the well wall to ensure the safety of the open caisson structure.

Description

Technical Field

[0001] The present invention relates to the technical field of construction of jacking working shafts, and specifically to a jacking working shaft sinking monitoring and control system and its construction method. Background Art

[0002] A jacking working shaft is a foundation pit excavated at the starting end and receiving end before jacking construction, providing an operating space for jacking construction and being a quite important link in jacking design and construction. The open caisson method is a commonly used method for the construction of jacking working shafts. First, the shaft wall is prefabricated on the ground surface, and then the soil is excavated inside the shaft. After overcoming the frictional resistance of the shaft wall by its own gravity, it sinks to the designed elevation. During the sinking process, the attitude and stress conditions of the working shaft are very complex. Existing monitoring methods usually can only monitor the deformation of the shaft body of the jacking working shaft, but it is very difficult to monitor its sinking attitude and mechanical properties. To ensure the structural safety during the sinking process of the working shaft, it is necessary to establish a monitoring system for the sinking attitude and stress characteristics. Summary of the Invention

[0003] The purpose of the present invention is to provide a jacking working shaft sinking monitoring and control system and its construction method, which can view the caisson attitude and stress data in real time and adjust the sinking attitude and shaft wall frictional resistance in time to ensure the structural safety of the caisson.

[0004] To solve the above technical problems, the technical solution adopted by the present invention is: a jacking working shaft sinking monitoring and control system, including a monitoring system arranged on the steel reinforcement cage of the working shaft and a control system arranged outside the working shaft. The monitoring system consists of a steel bar strain gauge, an earth pressure gauge, an inclination sensor, a collection box and a computer;

[0005] The control system consists of a grouting pipeline, a grouting pump, a grouting pump controller, a hydraulic jack and a jack controller;

[0006] The longitudinal main bars in the middle of the steel reinforcement cage are truncated to form a break, and the steel bar strain gauge is welded to the break of the longitudinal main bar. A grouting pipe is welded between adjacent two layers of circumferential main bars. An earth pressure gauge base is arranged through between two layers of circumferential main bars below the grouting pipe, and the earth pressure gauge base is fixedly welded to the steel reinforcement cage;

[0007] An earth pressure gauge is installed on the earth pressure gauge base, and an inclination sensor and a collection box are installed on the inner wall of the working shaft;

[0008] The grouting pipe is connected with a grouting pipeline. A hardened foundation is arranged around the outside of the working shaft. A jack support is arranged on the hardened foundation through high-strength bolts. The hydraulic jack in the control system is installed on the jack support, and the hydraulic jack is connected with the jack controller to achieve control.

[0009] In a preferred solution, the distance between adjacent two layers of the circumferential main reinforcement is not less than the diameter of the end of the earth pressure cell base.

[0010] In a preferred solution, both ends of the grouting pipe and the earth pressure cell base are flush with the inner and outer walls of the working well respectively.

[0011] In a preferred solution, a collection module and a wireless transmission module are provided in the collection box. The collection module is connected to the steel bar strain gauge, the earth pressure cell and the inclination sensor, and a wireless signal transmission is formed between the wireless transmission module and the computer.

[0012] In a preferred solution, a power supply for power supply is also provided in the collection box, and a solar panel is provided on the top of the collection box. The solar panel is connected to the power supply and charges the power supply.

[0013] In a preferred solution, a grouting pump is provided on the grouting pipeline, and the grouting pump is connected to a grouting pump controller.

[0014] In a preferred solution, the working well is a rectangular caisson. There are four steel bar strain gauges and four earth pressure cells, which are respectively installed on the four side walls of the working well, and there are two inclination sensors which are installed on two adjacent side walls of the working well.

[0015] The construction method based on the above-mentioned jacking working well sinking monitoring and control system specifically includes the following steps:

[0016] 1) Install the monitoring system and the control system on the working well;

[0017] 2) Excavate and sink, start collecting data by using the monitoring system, and transmit the data to the computer through the wireless transmission module in the collection box. The computer processes and analyzes the data according to a predetermined program;

[0018] 3) The computer judges the inclination direction of the working well according to the data of the inclination sensor, and compares the measured inclination angle with the preset limit inclination angle;

[0019] 4) When the measured inclination angle is greater than the preset limit inclination angle, the computer sends an instruction to the jack controller of the inclined side wall of the well, and activates the corresponding hydraulic jack;

[0020] 5) When the jacking force of the hydraulic jack reaches the upper limit that the well wall concrete can bear or the well wall is vertical, the jacking force of the hydraulic jack stops rising and remains unchanged;

[0021] 6) The computer calculates the friction coefficient between the well wall and the soil body according to the test data of the steel bar strain gauge and the earth pressure cell, and predicts the subsequent sinking frictional resistance of the caisson;

[0022] 7) When the frictional resistance is greater than the gravity of the open caisson, the computer sends an instruction to the grouting pump controller to turn on the grouting pump for reducing resistance by grouting, so as to reduce the friction coefficient between the shaft wall and the soil mass;

[0023] 8) Continue to excavate and sink, and repeat steps 2) to 7) until it sinks to the designed elevation.

[0024] In the preferred solution, in the said step 5), the maximum jacking force of the hydraulic jack is calculated as follows:

[0025]

[0026] In the formula:

[0027] σc is the concrete compressive strength;

[0028] A is Hydraulic the contact area between the jack and the shaft wall.

[0029] In the preferred solution, in the said step 6), the friction coefficient between the shaft wall and the soil mass is calculated as follows:

[0030]

[0031] In the formula:

[0032] ε a1 is the average value of the test values of the four steel bar strain gauges at the bottommost monitoring section in the current working condition;

[0033] εan is the average value of the test values of the four steel bar strain gauges at the topmost monitoring section in the current working condition;

[0034] As is the cross-sectional steel bar area of the open caisson;

[0035] Es is the elastic modulus of the steel bar;

[0036] Ac is the cross-sectional concrete area of the open caisson;

[0037] Ec is the elastic modulus of the concrete;

[0038] Pa1 is the average value of the test values of the four earth pressure gauges at the bottommost monitoring section in the current working condition;

[0039] Pan is the average value of the test values of the four earth pressure gauges at the topmost monitoring section in the current working condition;

[0040] a andb are the length and width of the open caisson respectively;

[0041] h is the vertical distance between the lowermost monitoring section and the uppermost monitoring section in the current working condition;

[0042] The subsequent prediction and calculation of the sinking frictional resistance are as follows:

[0043]

[0044] In the formula: H is the total sinking length of the open caisson.

[0045] A soft ground pipe jacking instability force monitoring system and an instability force calculation and processing method provided by the present invention have the following beneficial effects by adopting the above structure and method:

[0046] (1) It can monitor and view the attitude and force conditions during the sinking process of the pipe jacking working well in real time, and control the sinking state of the working well. At the same time, the computer can analyze the sinking attitude and force conditions of the open caisson according to the test data, and make corresponding adjustment measures in time to ensure the safe and rapid sinking of the pipe jacking working well and improve the construction quality;

[0047] (2) Using solar panels to supply power to the acquisition box, avoiding external cables, realizing the long-term uninterrupted operation of the monitoring system, and improving the safety of monitoring;

[0048] (3) Realize the wireless real-time transmission of data, avoid the inconvenience of on-site manual collection, improve the collection efficiency, and reduce the impact on construction. [[ID=3�]]BRIEF DESCRIPTION OF THE DRAWINGS

[0049] The present invention will be further described below with reference to the drawings and embodiments:

[0050] Figure 1 is the installation drawing of the earth pressure base and the reinforcing bar strain gauge of the present invention.

[0051] Figure 2 is the layout drawing of the monitoring system of the present invention.

[0052] Figure 3 is the internal layout drawing of the acquisition box of the present invention.

[0053] Figure 4 is the layout drawing of the regulation system of the present invention.

[0054] Figure 5 is the plan layout drawing of the monitoring and regulation system of the present invention.

[0055] Figure 6 is the monitoring section setting drawing of the present invention.

[0056] Figure 7 ​This is a schematic diagram of the control method of the present invention.

[0057] In the figure: steel cage 1, circumferential main reinforcement 2, longitudinal main reinforcement 3, grouting pipe 4, earth pressure cell base 5, reinforcement strain gauge 6, earth pressure cell 7, inclination sensor 8, acquisition box 9, solar panel 10, acquisition module 11, wireless transmission module 12, power supply 13, computer 14, filter plate 15, grouting pipeline 16, grouting pump 17, grouting pump controller 18, hardened foundation 19, jack support 20, high-strength bolt 21, hydraulic jack 22, jack controller 23. Specific implementation mode

[0058] Example 1:

[0059] As Figure 1 shown, a jacking working shaft sinking monitoring and control system includes a monitoring system arranged on the steel cage 1 of the working shaft and a control system arranged outside the working shaft. The monitoring system is composed of a reinforcement strain gauge 6, an earth pressure cell 7, an inclination sensor 8, an acquisition box 9 and a computer 14;

[0060] The control system is composed of a grouting pipeline 16, a grouting pump 17, a grouting pump controller 18, a hydraulic jack 22 and a jack controller 23;

[0061] The longitudinal main reinforcement 3 in the middle of the steel cage 1 is cut off to form a break, and the reinforcement strain gauge 6 is welded to the break of the longitudinal main reinforcement 3. A grouting pipe 4 is welded between adjacent two layers of circumferential main reinforcements 2. An earth pressure cell base 5 is arranged through between two layers of circumferential main reinforcements 2 below the grouting pipe 4, and the earth pressure cell base 5 is fixedly welded to the steel cage 1;

[0062] An earth pressure cell 7 is installed on the earth pressure cell base 5, and an inclination sensor 8 and an acquisition box 9 are installed on the inner wall of the working shaft;

[0063] The grouting pipe 4 is connected with a grouting pipeline 16. A hardened foundation 19 is arranged around the outside of the working shaft. A jack support 20 is arranged on the hardened foundation 19 through high-strength bolts 21. The hydraulic jack 22 in the control system is installed on the jack support 20, and the hydraulic jack 22 is connected with the jack controller 23 to realize control.

[0064] In a preferred solution, the distance between adjacent two layers of the circumferential main reinforcements 2 is not less than the end diameter of the earth pressure cell base 5. When the distance between the circumferential main reinforcements 2 is less than the tail diameter of the earth pressure cell base 4, the earth pressure cell base 5 should be cut off through the upper circumferential main reinforcement 2.

[0065] In a preferred embodiment, both ends of the grouting pipe 4 and the soil pressure gauge base 5 are flush with the inner and outer walls of the working well. During the concrete pouring, the front and rear ends of the grouting pipe 4 and the soil pressure gauge base 5 need to be blocked to prevent concrete from entering them.

[0066] In a preferred embodiment, as Figure 2 , 3 , 5, a collection module 11 and a wireless transmission module 12 are provided in the collection box 9. The collection module 11 is connected to the steel bar strain gauge 6, the soil pressure gauge 7, and the inclination sensor 8, and a wireless signal transmission is formed between the wireless transmission module 12 and the computer 14.

[0067] In a preferred embodiment, a power supply 13 for power supply is further provided in the collection box 9. A solar panel 10 is provided on the top of the collection box 9, and the solar panel 10 is connected to the power supply 13 to charge the power supply 13.

[0068] In a preferred embodiment, as Figure 4 , 5 , a grouting pump 17 is provided on the grouting pipeline 16, and the grouting pump 17 is connected to the grouting pump controller 18.

[0069] In a preferred embodiment, as Figure 6 , the working well is a rectangular caisson. There are four steel bar strain gauges 6 and four soil pressure gauges 7, which are respectively installed on the four side walls of the working well, and there are two inclination sensors 8, which are installed on two adjacent side walls of the working well.

[0070] Embodiment 2:

[0071] As Figure 7 , on the basis of Embodiment 1, the construction method of the jacking working well sinking monitoring and control system specifically includes the following steps:

[0072] 1) Install the monitoring system and the control system on the working well;

[0073] 2) Excavate and sink, start collecting data using the monitoring system, and transmit the data to the computer 14 through the wireless transmission module (12) in the collection box 9. The computer 14 processes and analyzes the data according to a predetermined program;

[0074] 3) The computer 14 determines the inclination direction of the working well according to the data of the inclination sensor 8, and compares the measured inclination angle with the preset limit inclination angle (the size of the preset limit inclination angle is determined according to the actual engineering conditions);

[0075] 4) When the measured inclination angle is greater than the preset limit inclination angle, the computer 14 sends an instruction to the jack controller 23 of the inclined side wall to activate the corresponding hydraulic jack 22;

[0076] 5) When the jacking force of the hydraulic jack 22 reaches the upper limit that the shaft wall concrete can withstand or when the shaft wall is vertical, the jacking force of the hydraulic jack 22 stops rising and remains unchanged. When the measured inclination angle is less than the preset limit inclination angle, the hydraulic jack 22 retracts;

[0077] 6) The computer 14 calculates the friction coefficient between the shaft wall and the soil mass based on the test data of the steel strain gauges 6 and the earth pressure gauges 7, and predicts the sinking frictional resistance of the subsequent open caisson;

[0078] 7) When the frictional resistance is greater than the gravity of the open caisson, the computer 14 issues an instruction to the grouting pump controller 18 to turn on the grouting pump (17) for grouting to reduce the resistance, so as to reduce the friction coefficient between the shaft wall and the soil mass. When the shaft wall frictional resistance meets the sinking requirements, the grouting stops;

[0079] 8) Continue to excavate and sink, repeating steps 2) to 7) until it sinks to the designed elevation.

[0080] Embodiment 3:

[0081] Based on Embodiment 2, in step 5) above, the maximum jacking force of the hydraulic jack 22 is calculated as follows:

[0082]

[0083] In the formula:

[0084] σc is the concrete compressive strength;

[0085] A is Hydraulic the contact area between the jack and the shaft wall.

[0086] In step 6) above, the friction coefficient between the shaft wall and the soil mass is calculated as follows:

[0087]

[0088] In the formula:

[0089] ε a1 is the average value of the test values of the four steel strain gauges at the lowest monitoring section in the current working condition;

[0090] εan is the average value of the test values of the four steel strain gauges at the topmost monitoring section in the current working condition;

[0091] As is the cross-sectional steel area of the open caisson;

[0092] Es is the elastic modulus of the steel;

[0093] Acis the cross-sectional concrete area of the open caisson;

[0094] Ec is the elastic modulus of concrete;

[0095] Pa1 is the average value of the test values of the four earth pressure gauges at the bottommost monitoring section in the current working condition;

[0096] Pan is the average value of the test values of the four earth pressure gauges at the topmost monitoring section in the current working condition;

[0097] a and b are the length and width of the open caisson respectively;

[0098] h is the vertical distance between the bottommost monitoring section and the topmost monitoring section in the current working condition;

[0099] The prediction calculation of the subsequent sinking frictional resistance is as follows:

[0100]

[0101] In the formula: H is the total sinking length of the open caisson.

Claims

1. Construction method of a jacking working shaft sinking monitoring and control system, characterized in that: The subsidence monitoring and control system includes a monitoring system installed on the steel reinforcement cage (1) of the working shaft and a control system installed outside the working shaft. The monitoring system consists of a steel bar strain gauge (6), an earth pressure gauge (7), an inclination sensor (8), a collection box (9), and a computer (14). The control system consists of a grouting pipeline (16), a grouting pump (17), a grouting pump controller (18), a hydraulic jack (22), and a jack controller (23). The longitudinal main steel bars (3) in the middle of the steel reinforcement cage (1) are truncated to form a fracture. The steel bar strain gauge (6) is welded at the fracture of the longitudinal main steel bars (3). A grouting pipe (4) is welded between adjacent two layers of circumferential main steel bars (2). An earth pressure gauge base (5) is arranged through between two layers of circumferential main steel bars (2) below the grouting pipe (4), and the earth pressure gauge base (5) is fixedly welded to the steel reinforcement cage (1). The earth pressure gauge (7) is installed on the earth pressure gauge base (5), and the inclination sensor (8) and the collection box (9) are installed on the inner wall of the working shaft. The grouting pipe (4) is connected with the grouting pipeline (16). A hardened foundation (19) is arranged around the outside of the working shaft. A jack support (20) is arranged on the hardened foundation (19) through high-strength bolts (21). The hydraulic jack (22) in the control system is installed on the jack support (20), and the hydraulic jack (22) is connected with the jack controller (23) to achieve control. The construction method of the above-mentioned pipe jacking working shaft subsidence monitoring and control system includes the following steps: 1) Install the monitoring system and the control system on the working shaft. 2) Excavate and sink, start collecting data by using the monitoring system, and transmit the data to the computer (14) through the wireless transmission module (12) in the collection box (9). The computer (14) processes and analyzes the data according to a predetermined program. 3) The computer (14) judges the inclination direction of the working shaft according to the data of the inclination sensor (8), and compares the measured inclination angle with the preset limit inclination angle. 4) When the measured inclination angle is greater than the preset limit inclination angle, the computer (14) sends an instruction to the jack controller (23) on the inclined side well wall to activate the corresponding hydraulic jack (22). 5) When the jacking force of the hydraulic jack (22) reaches the upper limit that the well wall concrete can bear or the well wall is vertical, the jacking force of the hydraulic jack (22) stops rising and remains unchanged. 6) The computer (14) calculates the friction coefficient between the well wall and the soil body according to the test data of the steel bar strain gauge (6) and the earth pressure gauge (7), and predicts the subsequent sinking frictional resistance of the caisson. 7) When the frictional resistance is greater than the gravity of the caisson, the computer (14) sends an instruction to the grouting pump controller (18) to start the grouting pump (17) for grouting to reduce the resistance, so as to reduce the friction coefficient between the well wall and the soil body. 8) Continue to excavate and sink, and repeat steps 2) to 7) until it sinks to the design elevation. In the above step 6), the calculation of the friction coefficient between the well wall and the soil body is as follows: ； In the formula: ε a1 is the average value of the test values of the four steel bar strain gauges at the lowest monitoring section in the current working condition; εan is the average value of the test results of four steel bar strain gauges at the topmost monitoring section in the current working condition; As is the cross-sectional steel bar area of the open caisson; Es is the elastic modulus of the steel bar; Ac is the cross-sectional concrete area of the open caisson; Ec is the elastic modulus of concrete; Pa1 is the average value of the test values of four earth pressure gauges at the lowest monitoring section in the current working condition; Pan is the average value of the test results of four earth pressure gauges at the topmost monitoring section in the current working condition; a and b are the length and width of the caisson respectively; h is the vertical distance between the bottommost monitoring section and the topmost monitoring section in the current working condition; The prediction calculation of the subsequent sinking frictional resistance is as follows: ； In the formula: H is the total length of the open caisson sinking.

2. The construction method of a jacking working shaft sinking monitoring and control system according to claim 1, characterized in that: The distance between adjacent circumferential main reinforcements (2) is not less than the end diameter of the earth pressure cell base (5).

3. The construction method of a jacking working shaft sinking monitoring and control system according to claim 1, characterized in that: Both ends of the grouting pipe (4) and the earth pressure cell base (5) are flush with the inner and outer walls of the working well respectively.

4. The construction method of a jacking shaft sinking monitoring and control system according to claim 1, characterized in that: A collection module (11) and a wireless transmission module (12) are provided in the collection box (9). The collection module (11) is connected to the reinforcing bar strain gauge (6), the earth pressure cell (7) and the inclination sensor (8), and a wireless signal transmission is formed between the wireless transmission module (12) and the computer (14).

5. The construction method of a jacking working shaft sinking monitoring and control system according to claim 4, characterized in that: A power supply (13) for power supply is further provided in the collection box (9). A solar panel (10) is provided on the top of the collection box (9), and the solar panel (10) is connected to the power supply (13) and charges the power supply (13).

6. The construction method of a jacking working shaft sinking monitoring and control system according to claim 1, characterized in that: A grouting pump (17) is provided on the grouting pipeline (16), and the grouting pump (17) is connected to the grouting pump controller (18).

7. The construction method of a jacking shaft sinking monitoring and control system according to claim 1, characterized in that: The working well is a rectangular caisson. There are four reinforcing bar strain gauges (6) and four earth pressure cells (7), which are respectively installed on the four side walls of the working well. There are two inclination sensors (8), which are installed on two adjacent side walls of the working well.

8. The construction method of a jacking shaft sinking monitoring and control system according to claim 1, characterized in that: In step 5), the maximum jacking force of the hydraulic jack (22) is calculated as follows: ； In the formula: σc is the compressive strength of concrete; A For Hydraulic the contact area between the jack and the shaft wall

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