Concrete pumping amount control device and method for immersed tube type CFG pile

Abstract

The application discloses a kind of sinking pipe type CFG pile concrete pumping quantity control device and method, its device includes: depth sensing device, it is used to detect the pressure suffered by the inner and outer wall of sinking pipe of pile machine and output;And, concrete pumping control device is connected depth sensing device, and it is used to connect and control concrete pump;The depth sensing device includes two groups of pressure sensors, one group of the pressure sensor is used as pressure detection distributed on the outside of sinking pipe, one group of the pressure sensor is used as pressure detection distributed on the inside of sinking pipe;Two groups of the pressure sensor are all arranged multiple along the length direction and circumference direction of sinking pipe.This application has the effect of improving CFG pile construction grouting control precision, improving CFG pile quality and CFG pile construction cost control ability.

Description

Technical Field

[0001] This application relates to the field of foundation treatment technology, and in particular to a device and method for controlling the concrete pumping volume of driven CFG piles. Background Technology

[0002] CFG piles are short for cement fly ash gravel piles. They are a commonly used form of soft soil foundation treatment and are suitable for treating cohesive soil, silt, sandy soil, and silty soil with a relatively hard soil layer at the pile tip and a bearing capacity standard value of not less than 70 kPa, as well as unconsolidated artificial fill foundations.

[0003] During the construction of driven CFG piles, there are two construction methods for concrete pouring:

[0004] 1. The tanker truck unloads the material into the hopper, and then a crane is used to lift the hopper to the top of the driven pile for concrete pouring;

[0005] 2. The tanker truck unloads the material into the hopper of the ground pump. The outlet of the ground pump is connected to the top of the submerged pipe through a pipeline. The concrete is pumped to the top of the submerged pipe through the ground pump.

[0006] The first method of concrete pouring has the following drawbacks: (1) Slow concrete placement speed. The concrete placement process requires the use of cranes, concrete mixer trucks and CFG pile foundations. The process involves the crane lowering the hopper to the concrete mixer truck, the mixer truck unloading the material, and the hopper being lifted to the CFG pile foundation bucket. Each concrete placement process takes 2 to 5 minutes, resulting in slow progress of CFG pile foundation construction; (2) Uncertain concrete volume. The material is released from the mixer truck each time, making it impossible to accurately control the amount of concrete used; (3) Safety problems such as spillage and overturning are prone to occur during the hoisting of the hopper.

[0007] The second method has several drawbacks: (1) It is not easy to control the volume of concrete pumped by ground pumps. The amount of concrete used for piles of different lengths is different. Under the same flow rate, the pumping time is different. Since the pumping time is controlled manually, it is difficult to accurately control the amount of concrete used. (2) Since the pumping team and the pile foundation team are not the same team, concrete is often pumped after the CFG design pile length is completed, which eventually leads to the rupture of the pumping pipeline and further wastes concrete.

[0008] Based on the above, this application proposes a new technical solution. Summary of the Invention

[0009] In order to improve the accuracy of CFG pile construction grouting control, enhance the quality of CFG piles, and improve the ability to control CFG pile construction costs, this application provides a concrete pumping volume control device for driven CFG piles.

[0010] In the first aspect, this application provides a concrete pumping volume control device for driven CFG piles, which adopts the following technical solution:

[0011] A concrete pumping volume control device for driven CFG piles includes:

[0012] A depth sensing device, used to detect and output the pressure exerted on the inner and outer walls of the pile driver's driven tube; and,

[0013] A concrete pumping control device, which is connected to a depth sensing device and is used to connect to and control a concrete pump.

[0014] The depth sensing device includes two sets of pressure sensors. One set of pressure sensors is distributed on the outside of the immersed tube for pressure detection, and the other set of pressure sensors is distributed on the inside of the immersed tube for pressure detection. Multiple pressure sensors are arranged along the length and circumference of the immersed tube in both sets.

[0015] Optionally, the pressure sensors distributed on the outside of the immersed tube are arranged vertically with a spacing of 0.3-0.8m, and there are at least two arranged in a circumferential direction; the pressure sensors distributed on the inside of the immersed tube are arranged vertically with a spacing of 0.3-0.8m, and there are at least three arranged in a circumferential direction.

[0016] Secondly, this application provides a method for controlling the concrete pumping volume based on any of the above-described driven CFG pile concrete pumping volume control devices, employing the following technical solution:

[0017] A method for controlling the concrete pumping volume based on any of the above-described driven CFG pile concrete pumping volume control devices, wherein the concrete pumping control device is configured as follows:

[0018] Obtain the vertical spacing value d1 of the pressure sensors on the outside of the immersed tube and the pile diameter r;

[0019] The feedback data from the pressure sensors distributed on the outside of the immersed tube is obtained, and it is determined whether each pressure sensor has reached the drilling standard. If so, it is defined as a pressure node.

[0020] The number of pressure-bearing nodes on the outer side along the length of the immersed tube is counted and denoted as s1;

[0021] Calculate the concrete usage C, ensuring it satisfies Formula 1: ;

[0022] Obtain the flow rate V of the concrete pump;

[0023] Calculate the pumping time t, and let t satisfy Formula 2: ;

[0024] Let T1 be the start time of concrete pumping, and T2 be the end time of pumping. ;

[0025] The preset concrete pump shutdown control parameters are triggered at time T2.

[0026] Optionally, the concrete pumping control device is configured as follows:

[0027] The pressure sensors on the same circumference of the outer side of the immersed tube are respectively , ... Where n is the regular sorting value;

[0028] like and If the difference is less than the preset fault threshold and greater than the reference soil penetration threshold, then the corresponding pressure sensor meets the drilling standard.

[0029] Optionally, the concrete pumping control device is configured as follows:

[0030] If the number of pressure-sensitive nodes along the outer length of the immersed tube decreases, the current time is defined as the initial time node for tube extraction.

[0031] After defining the initial node for pipe removal, if the remaining pressure-bearing nodes are at the same length position as the submerged pipe, then the current time node is the end of the injection process, triggering the pumping end process, and performing closed-loop verification based on time T2.

[0032] Optionally, the concrete pumping control device is configured as follows:

[0033] The pressure sensors on the same circumference inside the immersed tube are respectively , ... ;

[0034] like and If the difference is less than the filling pressure error threshold and is greater than the reference grouting pressure threshold respectively, then the corresponding pressure sensor reaches the concrete grouting pressure standard and is recorded as the qualified pressure point.

[0035] The reference grouting pressure threshold is corrected at the end of the grouting time node using a preset pile head pressure correction value.

[0036] Optionally, the triggering of the pumping termination process, and the closed-loop verification based on time T2, includes:

[0037] Based on the compliant pressure point and the corresponding time parameters, generate a curve showing the change of the compliant pressure point over time;

[0038] If the change curve matches the preset pressure injection standard parameters, the process will stop at time T2 and trigger the output of the preset concrete pump shutdown control parameters. The matching correction time parameters will be retrieved from the preset pressure tank correction time database based on the characteristics of the change curve.

[0039] The time T2 is corrected using the time correction parameter to obtain T3, and the preset concrete pump shutdown control parameters are retried at T3.

[0040] Optionally, the concrete pumping control device is configured as follows:

[0041] Obtain the pile length correction value d2;

[0042] Calculate the pile length L, and let it satisfy Formula 3: ;

[0043] make .

[0044] In summary, this application includes at least one of the following beneficial technical effects: the sinking depth of the immersed tube can be obtained by utilizing the changes in sensors on the outside of the immersed tube, and then the theoretical concrete volume usage can be calculated by the concrete pumping control device based on the depth and the fixed properties (diameter) of the immersed tube; subsequently, by using the concrete pumping control device to obtain the flow feedback from the flow meter on a certain concrete conveying pipeline, the closing time can be calculated based on the opening time of the concrete pump and valve, thereby automatically shutting down, effectively controlling the amount of CFG pile concrete used, greatly avoiding waste problems, and preventing the problem of cutting corners. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the control architecture of this device. Detailed Implementation

[0046] The following is in conjunction with the appendix Figure 1 This application will be described in further detail.

[0047] This application discloses a concrete pumping volume control device for driven CFG piles.

[0048] Reference Figure 1 The concrete pumping volume control device for driven CFG piles includes:

[0049] A depth sensing device, used to detect and output the pressure exerted on the inner and outer walls of the pile driver's driven tube; and,

[0050] A concrete pumping control device, which is connected to a depth sensing device and is used to connect to and control a concrete pump.

[0051] In this embodiment, the depth sensing device includes multiple pressure sensors; it is understood that the sensors (or strain gauges, sensors) are equipped with signal transmission and conversion processing devices to convert the pressure on the inside and outside of the immersed tube into electrical signals and transmit them back to the concrete pumping control device.

[0052] In this embodiment, the concrete pumping control device includes a controller composed of an integrated board with an IC chip as its core. The controller is connected to a pressure sensor via terminals and controls the motor of the concrete pump and the electric valve on the feed pipe of the concrete pump through an adapted drive controller and frequency converter.

[0053] It is understandable that the aforementioned integrated board integrates commonly used functional modules such as clock / timing modules, RAM, and A / D or D / A converters. This is existing technology and will not be described in detail here.

[0054] In this application, multiple pressure sensors are divided into two groups based on their relative positions to the immersed tube; one group is located on the outside of the immersed tube; the other group is located on the inside of the immersed tube; specifically:

[0055] outer side of the immersed tube:

[0056] 1) Pressure sensors are vertically arranged at intervals of 0.3-0.8m, preferably 0.5m;

[0057] 2) At least two pressure sensors, such as two, are installed along the circumference of the same outer wall relative to the length of the immersed tube.

[0058] Inside of the immersed tube:

[0059] 1) Pressure sensors are vertically arranged at intervals of 0.3-0.8m, preferably 0.5m;

[0060] 2) At least three pressure sensors, such as three, are installed along the circumference of the same outer wall relative to the length of the immersed tube.

[0061] The advantages of the above design are: firstly, sensors in the same circumferential direction verify each other, avoiding control errors caused by any malfunction; secondly, sensors in the same circumferential direction cooperate with each other to help users more comprehensively detect the circumferential internal and external forces. The reason why there are fewer sensors on the outer side than the inner side is that the outer pressure detection is mainly used to determine the depth of the pipe penetration into the soil, and two sensors are sufficient as a double insurance. The inner side is different. A key role of the inner side circumferential pressure detection is to ensure the degree of compaction of each part of the pile and to ensure the quality of the pile.

[0062] After applying this device, the depth of the immersed tube can be obtained by the changes in the sensors on the outside of the immersed tube. Then, based on the depth and the fixed properties (diameter) of the immersed tube, the theoretical concrete volume can be calculated by the concrete pumping control device. Subsequently, by using the concrete pumping control device to obtain the flow feedback from the flow meter on a concrete delivery pipeline, the closing time can be calculated based on the opening time of the concrete pump and valve, thereby automatically shutting down the system. This effectively controls the amount of concrete used in the CFG pile, greatly avoiding waste and preventing the problem of cutting corners.

[0063] In summary, this device has the following advantages:

[0064] 1) By using sensing technology, the length of the immersed tube is accurately measured, and then the amount of pumped concrete required is calculated;

[0065] 2) It can accurately control the concrete pumping volume based on the calculated concrete pumping demand, thereby reducing concrete waste.

[0066] 3) By combining this induction technology with pumped concrete technology, the construction efficiency of driven CFG piles can be greatly improved.

[0067] This application also discloses a method for controlling the concrete pumping volume based on the above-mentioned immersed tube CFG pile concrete pumping volume control device.

[0068] The following are specific examples for explanation:

[0069] Taking the soft soil foundation treatment of a municipal engineering project as an example, the designed diameter of the CFG piles for this project is 500mm, with a total designed pile length of 150,000 meters. The construction process used on site is a vibratory driven CFG pile driver + concrete pumping method. At the beginning of the project, the QC team conducted a cost-saving and over-limit analysis on the CFG pile construction in five areas and found that the concrete over-limit phenomenon was serious, with an over-limit frequency of 64% and an average over-limit amount of 27.3%. The specific over-limit situation is shown in the table below: CFG Pile Over-Limit Statistics Table

[0070] project unit 25th District 26 districts 27th District 28th District 20 districts total Construction quantity root 180 210 222 252 96 960 Excess quantity root 90 120 144 180 42 576 Chaofang ≤10% 6 6 18 24 12 66 Chaofang 10%~20% 18 18 42 18 12 108 Chaofang 20%~30% 42 72 66 78 6 210 Chaofang 30%~50% 24 24 18 60 12 138

[0071] Assuming a project designs 100,000 meters of φ500mm CFG piles, the theoretical concrete usage would be approximately 19,635 m³. According to the table above, the excess volume is 5,360 m³. Based on the local price information from January 2019, the unit price of C25 concrete (excluding tax) is 560 yuan / m³, resulting in an economic loss of 3 million yuan due to the excess concrete usage. Using the technology described in this application, it is expected that the excess volume can be controlled within 3%, reducing economic losses by an estimated 2.67 million yuan.

[0072] This application discloses a method for controlling the concrete pumping volume based on the above-mentioned driven CFG pile concrete pumping volume control device.

[0073] The method for controlling concrete pumping volume mainly involves controlling the process. This is achieved by configuring a concrete pumping control device and implementing the following specific functions using a programming language:

[0074] S1, Data Preparation, which includes:

[0075] Obtain the vertical spacing value d1 of the pressure sensors on the outside of the immersed tube and the pile diameter r;

[0076] The feedback data from the pressure sensors distributed on the outside of the immersed tube is obtained, and it is determined whether each pressure sensor has reached the drilling standard. If so, it is defined as a pressure node.

[0077] The number of pressure-bearing nodes on the outer side along the length of the immersed tube is counted and denoted as s1;

[0078] Obtain the flow rate V of the concrete pump;

[0079] S2. Analysis and calculation, which includes:

[0080] Calculate the concrete usage C, ensuring it satisfies Formula 1: ;

[0081] Calculate the pumping time t, and let t satisfy Formula 2: ;

[0082] Let T1 be the start time of concrete pumping, and T2 be the end time of pumping. ;

[0083] S3, control output, which includes:

[0084] The preset concrete pump shutdown control parameters are triggered at time T2; it can also be understood that the corresponding closing control parameters of the electric valve on the concrete delivery pipe.

[0085] In one embodiment of this method, regarding the aforementioned transfer criteria, specifically:

[0086] The pressure sensors on the same circumference of the outer side of the immersed tube are respectively , ... Where n is the sorting value.

[0087] Understandably, sensors at different heights (or, in other words, along the length of the immersed tube) are distinguished by their height values. The number 'n' mentioned above can be a left-hand or right-hand sequential number. Assuming two pressure sensors are in the same circumferential direction, for... , .

[0088] like and If the difference is less than the fault threshold (pre-entered by staff to prevent misjudgment caused by accuracy errors or differences in soil structure), and is greater than the reference soil entry threshold, then the corresponding pressure sensor meets the drilling standard.

[0089] That is, this application determines whether the sinking tube has sunk into the soil layer at a corresponding position based on changes in the pressure sensor on the outside of the sinking tube; the corresponding sinking depth, or pile length L, satisfies .

[0090] Understandably, if the distance between the lowest pressure sensor and the bottom of the submerged tube is not 0.5m, the difference exceeding 0.5m needs to be added, i.e., the zero point needs to be filled. Specifically:

[0091] Obtain the pile length correction value d2 (entered by staff through interactive devices such as keyboards and touch screens, including filling in the zero point and the height difference of the end exceeding the last sensor inserted into the soil).

[0092] Calculate the pile length L, and let it satisfy Formula 3: ;

[0093] make .

[0094] In one embodiment of this method, the concrete pumping control device is configured to:

[0095] If the number of pressure-sensitive nodes decreases (one ring at a time) as the length of the outer side of the immersed tube decreases towards the pressure sensor, then the current time is defined as the initial time node for tube extraction.

[0096] After defining the initial node for pipe removal, if the remaining pressure-bearing nodes are at the same length (height) position as the submerged pipe, then the current time node is the end of the injection process, triggering the pumping end process, and performing closed-loop verification based on time T2.

[0097] As can be seen from the above, the final pumping stop control during the concrete pouring process in this application is not simply based on the so-called time T2; because there are various disturbances in the pumping process, such as changes in pumping flow rate and CFG pile quality requirements, all of which have a certain impact; therefore, closed-loop verification is also performed.

[0098] Before performing closed-loop verification, this method requires the following details:

[0099] The pressure sensors on the same circumference inside the immersed tube are respectively , ... ;

[0100] like and If the difference is less than the filling pressure error threshold and is greater than the reference grouting pressure threshold, then the corresponding pressure sensor reaches the concrete grouting pressure standard and is recorded as the qualified pressure point.

[0101] The standard pressure point can be understood as: the concrete at that height of the submerged pipe is compressed to a degree that meets the construction standards and is sufficient to ensure the quality of the pile.

[0102] It should be noted that the reference grouting pressure threshold is corrected at the end of the grouting time point using a preset pile head pressure correction value.

[0103] The reason for needing to make corrections at the pile head is quite intuitive: the upper section and head section of the CFG pile have less concrete, resulting in reduced pressure; therefore, if the same threshold is applied as the lower section of the driven tube without threshold correction, it can easily lead to excessive concrete pumping.

[0104] To ensure the structural strength of the pile head, a vibrator can be used to penetrate and compact it subsequently.

[0105] Based on this, the above-mentioned process for triggering the pumping termination, and the closed-loop verification based on time T2, includes:

[0106] Based on the compliant pressure point and the corresponding time parameters, generate a curve showing the change of the compliant pressure point over time;

[0107] If the change curve matches the preset pressure injection standard parameters, the process will stop at time T2 and trigger the output of the preset concrete pump shutdown control parameters. The matching correction time parameters will be retrieved from the preset pressure tank correction time database based on the characteristics of the change curve.

[0108] The time T2 is corrected using the time correction parameter to obtain T3, and the preset concrete pump shutdown control parameters are retried at T3.

[0109] Assuming a rather extreme case, during 3 / 4 of the time of pipe extraction and grouting, there is no standard pressure point; that is, the grouting concrete remains in a certain state of fullness. The resulting change curve clearly does not conform to the preset pressure grouting parameters. In this case, if grouting is stopped at time T2, the pile will definitely have quality problems; therefore, it is necessary to continue pumping concrete after time T2 for compaction, which is the operation after the above judgment is negative.

[0110] The aforementioned corrected time parameters, namely the corresponding extended shutdown time for concrete pumping, are determined by construction personnel based on experience and actual verification. They are then matched one-to-one with the characteristics of various change curves and are ready for use.

[0111] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A method for controlling the concrete pumping volume based on a driven CFG pile concrete pumping volume control device, characterized in that, The concrete pumping control device is configured as follows: Obtain the vertical spacing value d1 of the pressure sensors on the outside of the immersed tube and the pile diameter r; The feedback data from the pressure sensors distributed on the outside of the immersed tube is obtained, and it is determined whether each pressure sensor has reached the drilling standard. If so, it is defined as a pressure node. The number of pressure-bearing nodes on the outer side along the length of the immersed tube is counted and denoted as s1; Calculate the concrete usage C, assuming it satisfies Formula 1: C = d1.s1.πr 2 ; Obtain the flow rate V of the concrete pump; Calculate the pumping time t, and let t satisfy Formula 2: t=C / V; Let T1 be the start time of concrete pumping, and T2 be the end time of pumping. Let T2 = T1 + t. The preset concrete pump shutdown control parameters are triggered at time T2. The concrete pumping volume control device for driven CFG piles includes: A depth sensing device, used to detect and output the pressure exerted on the inner and outer walls of the pile driver's driven tube; and, A concrete pumping control device, which is connected to a depth sensing device and is used to connect to and control a concrete pump. The depth sensing device includes two sets of pressure sensors. One set of pressure sensors is distributed on the outside of the immersed tube for pressure detection, and the other set of pressure sensors is distributed on the inside of the immersed tube for pressure detection. Multiple pressure sensors are arranged along the length and circumference of the immersed tube in both sets. The pressure sensors distributed on the outside of the immersed tube are arranged vertically with a spacing of 0.3-0.8m, and there are at least two arranged in a circumferential direction; the pressure sensors distributed on the inside of the immersed tube are arranged vertically with a spacing of 0.3-0.8m, and there are at least three arranged in a circumferential direction. The concrete pumping control device is configured as follows: If the number of pressure-sensitive nodes along the outer length of the immersed tube decreases, the current time is defined as the initial time node for tube extraction. After defining the initial node for pipe pulling, if the remaining pressure-bearing nodes are at the same length position as the submerged pipe, then the current time node is the end of the injection, triggering the pumping end process, and performing closed-loop verification based on time T2. The pressure sensors along the same circumference on the inner side of the immersed tube are b1, b2...b n ; If b n With b n-1 If the difference is less than the filling pressure error threshold and is greater than the reference grouting pressure threshold respectively, then the corresponding pressure sensor reaches the concrete grouting pressure standard and is recorded as the qualified pressure point. Among them, the reference grouting pressure threshold is corrected at the end of the grouting time node with a preset pile head pressure correction value; The process of triggering the pumping termination and performing closed-loop verification based on time T2 includes: Based on the compliant pressure point and the corresponding time parameters, generate a curve showing the change of the compliant pressure point over time; Determine whether the change curve matches the preset pressure grouting parameters. If not, stop at time T2 to trigger the output of the preset concrete pump shutdown control parameters, and call the matching correction time parameters from the preset pressure tank correction time database according to the characteristics of the change curve. The time T2 is corrected using the time correction parameter to obtain T3, and the preset concrete pump shutdown control parameters are retried at T3.

2. The method for controlling the concrete pumping volume based on the driven CFG pile concrete pumping volume control device according to claim 1, characterized in that, The concrete pumping control device is configured as follows: Let the pressure sensors along the same circumference on the outer side of the immersed tube be a1, a2...a... n Where n is the sorting value; If a n With a n-1 If the difference is less than the preset fault threshold and greater than the reference soil penetration threshold, then the corresponding pressure sensor meets the drilling standard.

3. The method for controlling the concrete pumping volume based on the driven CFG pile concrete pumping volume control device according to claim 2, characterized in that, The concrete pumping control device is configured as follows: Obtain the pile length correction value d2; Calculate the pile length L, and let it satisfy Formula 3: L=d1.s1+d2; Let C = L.π.r 2 .

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