Concrete temperature measuring device for underground diaphragm wall support

Abstract

The utility model discloses a concrete temperature measuring device for underground diaphragm wall support, which comprises temperature measuring guide pipes, three groups of temperature measuring guide pipes are respectively arranged on the left side, the middle part and the right side of each underground diaphragm wall along the horizontal direction, and each group is symmetrically provided with three temperature measuring guide pipes. The three temperature measuring conduits are respectively located at positions close to the front side, the middle and the rear side of the underground diaphragm wall, the bottoms of the temperature measuring conduits are flush with the bottom of the underground diaphragm wall, the tops of the temperature measuring conduits extend to the upper part of the ground, and each temperature measuring conduit is provided with three temperature measuring points; three temperature measuring leads with different lengths are arranged in each temperature measuring conduit; the front side and the rear side of each underground diaphragm wall are each provided with a set of n-shaped temperature measuring condensation pipes, one ends of the temperature measuring condensation pipes on the front side and the rear side are communicated, and the other ends of the temperature measuring condensation pipes on the front side and the rear side extend upwards to the position above the ground. The concrete temperature measuring device is convenient to use and easy to install, the temperature measuring wire can be recycled, the cost is effectively saved, and concrete temperature measurement and data accuracy are ensured.

Description

Technical Field

[0001] This utility model relates to the field of temperature measurement technology for diaphragm wall support, specifically to a concrete temperature measurement device for diaphragm wall support. Background Technology

[0002] With the acceleration of urbanization, the construction of infrastructure such as high-rise buildings and large-scale underground projects is booming. Diaphragm walls are widely used as an effective form of deep foundation pit support and underground structural wall. During the construction of diaphragm walls, the pouring of large-volume concrete is a crucial step. However, at present, the impact of temperature on the durability of underwater concrete and concrete encased in soil as permanent support methods is currently unknown. Therefore, temperature monitoring is of paramount importance.

[0003] Due to their large structural dimensions, large-volume concrete accumulates a significant amount of heat during the cement hydration heat release process, which is difficult to dissipate quickly. The cement hydration reaction is typically most intense in the early stages after pouring, generating substantial heat and causing a rapid rise in the internal temperature of the concrete. For example, with common C30 concrete, the peak of its cement hydration heat generally occurs 2-3 days after pouring, with the internal temperature potentially 30-50°C higher than the pouring temperature. Furthermore, due to the unique nature of diaphragm walls, with soil layers on both sides, the internal heat is difficult to dissipate, resulting in a significant temperature difference between the inside and outside. This stark contrast between the high internal temperature and the surrounding soil temperature creates a large temperature gradient between the concrete's interior and surface. Excessive temperature gradients can trigger non-uniform deformation of the concrete, leading to thermal stress. When this thermal stress exceeds the tensile strength of the concrete, it causes cracking. The appearance of cracks not only affects the appearance of the diaphragm wall but also severely weakens its load-bearing capacity, waterproofing performance, and durability, posing a significant safety hazard to the project.

[0004] Conventional methods for measuring the temperature of foundation slabs require installation after the reinforcement is tied and before concrete pouring. The temperature sensing wire must be tied to a single reinforcement bar, with its sensing element positioned at the measurement point. During tying, care must be taken to ensure the wire does not directly contact the reinforcement bar. However, this method presents the following problems for measuring the temperature of diaphragm walls:

[0005] 1. During the pouring process, it is difficult to ensure that the temperature measuring wire does not come into contact with the reinforcing steel, often resulting in inaccurate temperature data after pouring, failing to reflect the true internal temperature of the concrete, and causing significant misunderstandings in construction management. 2. When the temperature measuring wire is tied to the reinforcing steel, and the steel is fixed to the wall column reinforcement, the steel is prone to displacement during pouring, and even temperature measuring sections may break, leading to inaccurate temperature data that cannot be measured. 3. During the hoisting of the diaphragm wall reinforcement cage, the temperature measuring wire is easily damaged, making it impossible to measure data later. 4. The temperature measuring wires embedded in large-volume concrete cannot be recycled, resulting in high costs. 5. Traditional temperature measurement methods are only for temperature measurement; if there is a large temperature difference between the inside and the surface, conventional methods such as covering and insulation can only be used, but these methods are not suitable for diaphragm walls. Utility Model Content

[0006] The purpose of this invention is to provide a concrete temperature measuring device for underground continuous wall support, so as to solve the problems mentioned in the background art.

[0007] To achieve the above objectives, this utility model provides a concrete temperature measuring device for diaphragm wall support, comprising: a temperature measuring conduit, three sets of temperature measuring conduits arranged horizontally on the left, middle, and right sides of each diaphragm wall, with three temperature measuring conduits symmetrically arranged in each set, the three temperature measuring conduits being located near the front, middle, and rear sides of the diaphragm wall respectively, the bottom of the temperature measuring conduit being flush with the bottom of the diaphragm wall, the top extending to above the ground, and three temperature measuring points set vertically on each temperature measuring conduit; temperature measuring wires, three temperature measuring wires of different lengths installed inside each temperature measuring conduit; and temperature measuring condenser tubes, one set of "Z"-shaped temperature measuring condenser tubes installed on each of the front and rear sides of each diaphragm wall, with one end of the front and rear temperature measuring condenser tubes connected together and the other end extending upwards to above the ground.

[0008] In a preferred embodiment, the top of the temperature measuring conduit is 1m above the ground and the bottom of the temperature measuring conduit is sealed. The lengths of the three temperature measuring wires inside each temperature measuring conduit correspond to the three temperature measuring points of each temperature measuring conduit.

[0009] In a preferred embodiment, one set of temperature-sensing condenser tubes is disposed between the temperature-sensing conduit near the front and the middle temperature-sensing conduit, and the other set of temperature-sensing condenser tubes is disposed between the temperature-sensing conduit near the rear and the middle temperature-sensing conduit, and the two sets of temperature-sensing condenser tubes are symmetrically arranged.

[0010] In a preferred embodiment, the inner diameter of the zigzag-shaped temperature measuring condenser tube is 28mm, the vertical distance between the horizontal pipe sections in the temperature measuring condenser tube is 2m, the horizontal distance between the vertical pipe sections is 1m, and the temperature measuring conduit tube and the temperature measuring condenser tube are welded to the positions where they contact the underground continuous wall reinforcement.

[0011] In a preferred embodiment, the three temperature measuring points on each temperature measuring conduit are respectively arranged vertically at the middle of the wall, 1000mm from the bottom of the underground continuous wall, and 2000mm from the bottom of the crown beam, and horizontally at the middle of the wall, 100mm from one side edge, and 1000mm from one side edge.

[0012] In a preferred embodiment, a reference observation hole is provided on one side of the diaphragm wall in the foundation pit. A soil temperature measuring pipe is installed in the reference observation hole, and soil temperature measuring points are arranged on it for observing the soil temperature at the same time.

[0013] In a preferred embodiment, the top end of the temperature measuring wire is fixed with a tie wire, and the bottom is fixed to the temperature measuring conduit with a nylon rope. The temperature measuring conduit is filled with cement slurry with the same mix ratio as the poured concrete.

[0014] Compared with the prior art, the beneficial effects of this utility model are as follows: This utility model sets up temperature measuring conduits and temperature measuring condensers in the underground continuous wall, and arranges temperature measuring points for the conduits and soil. It uses temperature measuring wires and multi-channel temperature monitoring instruments to continuously measure the temperature, which is convenient to use, easy to install, and the temperature measuring wires can be recycled, effectively saving costs and ensuring the accuracy of concrete temperature measurement and data. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the arrangement of the temperature measuring conduit and the temperature measuring condenser tube of the present invention;

[0016] Figure 2 A three-dimensional view showing the temperature measurement point setup of this invention;

[0017] Figure 3 A plan view showing the temperature measurement point locations for this invention;

[0018] Figure 4 An elevation view showing the location of the temperature measurement points on the conduit in this invention.

[0019] Explanation of reference numerals in the attached figures:

[0020] 200. Temperature measuring conduit; 201. Diaphragm wall; 202. Temperature measuring condenser tube; 203. Temperature measuring point of conduit; 204. Temperature measuring point of soil. Detailed Implementation

[0021] The technical solutions in the embodiments of this utility model will be clearly and completely described below. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0022] Example 1

[0023] like Figures 1 to 4As shown, the preferred embodiment of this utility model of a concrete temperature measuring device for diaphragm wall support includes: a temperature measuring conduit 201, temperature measuring wires, and a temperature measuring condenser tube 202. Three sets of temperature measuring conduits 201 are arranged horizontally on the left, middle, and right sides of each diaphragm wall 200, with each set containing three symmetrically arranged conduits 201. The three conduits 201 are located near the front, middle, and rear sides of the diaphragm wall, respectively. The bottom of each conduit 201 is flush with the bottom of the diaphragm wall, and the top extends above the ground. Each conduit 201 has three temperature measuring points 203 arranged vertically. Each conduit 201 contains three temperature measuring wires of different lengths, the lengths of which correspond to the three temperature measuring points 203. The top ends of the temperature measuring wires are fixed with wire ties, and the bottoms are fixed to the temperature measuring conduits with nylon ropes. Each diaphragm wall 200 has a set of zigzag-shaped temperature measuring condenser tubes 202 installed on both the front and back sides, with one end of the temperature measuring condenser tubes 202 on the front and back sides connected and the other end extending upwards to the ground.

[0024] Furthermore, the top of the temperature measuring conduit 201 is 1m above the ground, and the bottom of the temperature measuring conduit 201 is sealed. The temperature measuring conduit 201 is filled with cement slurry with the same mix ratio as the poured concrete to prevent the poured concrete from entering the temperature measuring conduit.

[0025] Furthermore, one set of temperature-sensing condenser tubes 202 is positioned between the front-side temperature-sensing conduit 201 and the middle temperature-sensing conduit 201, while the other set is positioned between the rear-side temperature-sensing conduit 201 and the middle temperature-sensing conduit 201, with the two sets of temperature-sensing condenser tubes 202 arranged symmetrically. The inner diameter of the Z-shaped temperature-sensing condenser tubes 202 is 28mm. The vertical distance between the horizontal pipe sections 212 of the temperature-sensing condenser tubes 202 is 2m, and the horizontal distance between the vertical pipe sections 222 is 1m. The temperature-sensing conduit 201 and the temperature-sensing condenser tubes 202 are welded to the contact points with the underground continuous wall reinforcement.

[0026] Furthermore, the three temperature measuring points 203 on each temperature measuring conduit 201 are vertically arranged at the middle of the wall, 1000mm from the bottom of the underground continuous wall (e.g., Figure 4 (Mid-height h1) and 2000mm from the bottom of the cap beam (e.g.) Figure 4 The medium height (h2) is arranged horizontally at the middle of the wall, 100mm from one edge, and 1000mm from one edge.

[0027] Furthermore, a control observation hole is set up on one side of the diaphragm wall in the foundation pit. A soil temperature measuring conduit is installed in the control observation hole, with soil temperature measuring points 204 arranged on it for observing the soil temperature at the same time. The observation hole is drilled using a geological drill or anchor drill, and a soil temperature measuring conduit is installed. The length of the soil temperature measuring conduit is consistent with the depth of the diaphragm wall, and the height of the temperature measuring points on the soil temperature measuring conduit is consistent with the temperature measuring points on the diaphragm wall.

[0028] Example 2

[0029] The temperature measurement method of the device of this utility model is described below, including the following steps:

[0030] Step S1: Select monitoring samples from the underground continuous wall and design the temperature measuring conduit and temperature measuring condenser tube.

[0031] Specifically, step S1 includes: selecting three diaphragm walls 200 of different heights as monitoring samples; arranging three sets of temperature measuring conduits 201 on the left, middle, and right sides of each diaphragm wall, with three conduits in each set, and the three temperature measuring conduits 201 located near the front, middle, and rear sides of the diaphragm wall respectively. The bottom of the temperature measuring conduit 201 is flush with the bottom of the diaphragm wall, and the top is 1m above the ground. The bottom end of the temperature measuring conduit 201 is sealed and filled with cement grout to prevent concrete from entering the temperature measuring tube. Each temperature measuring conduit 201 contains three temperature measuring wires of different lengths, with the wire length selected according to the height of the diaphragm wall. Each diaphragm wall has a set of "Z"-shaped temperature measuring condenser tubes 202 on both the front and rear sides, with one end of the front and rear temperature measuring condenser tubes 202 connected and the other end extending upwards to the ground. One set of temperature-sensing condenser tubes 202 is positioned between the front and middle temperature-sensing conduit 201, while the other set is positioned between the rear and middle temperature-sensing conduit 201, with the two sets symmetrically arranged. In this embodiment, the temperature-sensing conduit 201 uses a steel sleeve with an inner diameter of 28mm, a wall thickness of 4mm, and a length of 35m. The inner diameter of the zigzag-shaped temperature-sensing condenser tubes 202 is 28mm. The horizontal pipe section distance within the temperature-sensing condenser tubes 202 is 2m, and the vertical pipe section distance is 1m. The temperature-sensing condenser tubes are welded to the underground continuous wall reinforcement at their contact points.

[0032] Step S2: Set up temperature measurement points, including: Three temperature measurement points 203 are set on each temperature measurement conduit 201. Vertically, these points are located at the center of the wall, 1000mm from the bottom of the diaphragm wall, and 2000mm from the bottom of the capping beam. Horizontally, they are located at the center of the wall, 100mm from one edge, and 1000mm from one edge. A reference observation hole 204 is set up within the foundation pit as a soil temperature measurement point 204 for observing the soil temperature during the same period. The observation hole is drilled using a geological drill or anchor drill, and a soil temperature measurement conduit is installed. The length of the soil temperature measurement conduit is consistent with the depth of the diaphragm wall, and the height of the temperature measurement points on the soil temperature measurement conduit is consistent with the temperature measurement points on the diaphragm wall. The soil temperature measurement conduit is filled with cement grout of the same medium.

[0033] Step S3: Install the temperature measuring conduit, temperature measuring condenser tube, and temperature measuring wire.

[0034] Specifically, step S3 includes:

[0035] Step S31: Mark the lengths of the temperature measuring leads, with the marks corresponding to the three temperature measuring points on each lead.

[0036] Step S32: Install the temperature-sensing condenser tube 202 during the fabrication of the diaphragm wall reinforcement cage. Because the overall structure of the temperature-sensing condenser tube is relatively large, it needs to be installed during the fabrication of the reinforcement cage. Since the diaphragm wall reinforcement cage requires dual-machine lifting, the temperature-sensing wire cannot be pre-set and must be laid after the reinforcement cage is lowered.

[0037] Step S33: Lower the steel cage.

[0038] Step S34: Install temperature measuring conduits and temperature measuring wires: Divide the 9 temperature measuring conduits into three groups and install them horizontally in the middle of the wall, 100mm from one edge, and 1000mm from one edge. Each group of 3 conduits is spaced apart in the same vertical plane. The temperature measuring conduits are welded and fixed to the underground continuous wall steel bars they are in contact with. Install the temperature measuring wires. The top end of the temperature measuring wires is fixed with tie wire, and the bottom is fixed to the temperature measuring conduits with nylon rope.

[0039] Due to the considerable depth of the diaphragm wall, accurately placing temperature measurement points at the predetermined depth is quite difficult, and it is challenging to precisely control the depth of the measurement points. Therefore, we marked the lengths of the temperature measurement guide wires, for example, marking the locations at 8m, 20m, and 40m.

[0040] Step S4: Pour concrete and measure the temperature of the large-volume concrete to obtain temperature data: After the reinforcing cage is lowered into the trench, concrete is poured through the grouting pipe. After pouring, cement slurry is injected into the temperature measuring conduit. The cement slurry should be of the same grade as the poured concrete to ensure that the temperature measuring conduit and the diaphragm wall are of the same medium. Temperature measurement of the cement slurry begins within 4 hours after the concrete pouring is completed. The temperature upon entering the formwork is recorded. Continuous temperature measurement is performed using a multi-channel temperature monitoring instrument, recording the temperature every 30 minutes. Temperature measurement is stopped when the temperature difference between the poured concrete and the ambient temperature is less than 20℃. After the temperature measurement period ends, the saved data is exported to form a temperature data list and a curve list.

[0041] If a large temperature difference is found between the inner and outer surfaces during the temperature measurement stage, low-heat or medium-heat cement can be used to reduce the heat of hydration. Appropriately increasing the amount of mineral admixtures can replace some of the cement, reducing the heat of hydration and improving the workability of the concrete. Optimizing the aggregate gradation by using continuously graded coarse aggregate reduces porosity, lowers cement usage, and thus reduces the heat of hydration.

[0042] Step S5: Analyze the temperature data and, based on the analysis results, determine the impact of the temperature difference between the inner and outer surfaces of the permanent support large-volume concrete on concrete cracks.

[0043] Furthermore, in step S5, the temperature data is analyzed, including:

[0044] Temperature change trend analysis: Observe the temperature change curves of each temperature measurement point over time, and compare the temperature changes of temperature measurement points at different depths and horizontal positions;

[0045] Thickness-direction temperature gradient analysis: Calculate the temperature difference between temperature measurement points at different depths to obtain the temperature gradient in the thickness direction;

[0046] Horizontal temperature gradient analysis: Analyze the temperature at different temperature measurement points on the same horizontal plane to understand the temperature uniformity in the horizontal direction.

[0047] Furthermore, in step S5, based on the analysis results, the influence of the temperature difference between the inner and outer surfaces of the permanent support mass concrete on concrete cracking is determined, including:

[0048] Assessing Crack Risk: During the concrete heating stage, if the temperature gradient between the surface temperature measurement point and the center temperature measurement point exceeds 25℃ / m, the risk of concrete cracking should be assessed. Temperature control measures must be implemented, including activating the condenser pipe and adding condensate water. The condensate water flow rate should be controlled between 1.2 and 2 m / s. The condensate water effectively absorbs heat from the concrete and circulates it away, maintaining a stable internal temperature. This flow rate range ensures that while the condensate water removes heat from the concrete, it does not create excessive scouring pressure on the pipes due to excessive speed, nor does it reduce cooling efficiency due to insufficient flow. The temperature difference between the condensate water inlet and outlet should be controlled between 5 and 10℃. A large temperature difference may lead to an excessive internal temperature gradient in the concrete, increasing the risk of cracking; a small temperature difference may indicate insufficient cooling efficiency. During the condensate injection process, the temperature changes at each temperature measurement point should be monitored closely to ensure that the cooling rate of the concrete inside the diaphragm wall is controlled within 2℃ / d. During the concrete hardening process, the rate at which the concrete dissipates heat to the surrounding soil should be obtained by monitoring the soil temperature. If the soil temperature rises rapidly and remains in a high-temperature environment, it indicates that the concrete is dissipating heat slowly and the internal temperature is too high, increasing the risk of cracking. If the soil temperature changes steadily, it indicates that the concrete is dissipating heat normally, which is helpful for assessing the stability of the internal temperature field of the concrete.

[0049] Durability impact: The effect of temperature change on concrete durability was analyzed. When the internal temperature of a large volume of concrete exceeds 65°C and it is exposed to a high-temperature environment for a long time, its durability will be reduced.

[0050] Temperature control effectiveness: Set a target temperature control value and compare the actual measured temperature data with the target value to evaluate the effectiveness of the temperature control measures. When the temperature difference at each temperature measurement point does not exceed the design specification of 25℃ after the use of condensate cooling measures, it indicates that the temperature control measures are effective. If the temperature control does not achieve the expected target, targeted adjustment suggestions are made. Specifically, if the temperature peak exceeds 65℃, the flow rate or density of the condensate pipe is increased. If the cooling rate of the concrete inside the underground continuous wall is greater than 2℃ / d, the insulation measures are adjusted.

[0051] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A concrete temperature measuring device for diaphragm wall support, characterized in that: include: Temperature measuring conduits (201), the three sets of temperature measuring conduits (201) are arranged horizontally on the left, middle and right sides of each underground continuous wall (200), and each set is symmetrically arranged with three temperature measuring conduits (201). The three temperature measuring conduits (201) are located on the front side, middle and rear side of the underground continuous wall, respectively. The bottom of the temperature measuring conduit (201) is flush with the bottom of the underground continuous wall, and the top extends to the ground. Each temperature measuring conduit (201) is provided with three temperature measuring points (203) in the vertical direction. Temperature measuring wires, each temperature measuring conduit (201) is equipped with three temperature measuring wires of different lengths; Temperature measuring condenser tubes (202): Each underground continuous wall (200) has a set of zig-shaped temperature measuring condenser tubes (202) on both the front and back sides, and the temperature measuring condenser tubes (202) on the front and back sides are connected at one end and extend upward to the ground.

2. The concrete temperature measuring device for diaphragm wall support according to claim 1, characterized in that: The top of the temperature measuring conduit (201) is 1m above the ground and the bottom of the temperature measuring conduit (201) is sealed. The lengths of the three temperature measuring wires in each temperature measuring conduit (201) correspond to the three temperature measuring points (203) of each temperature measuring conduit (201).

3. The concrete temperature measuring device for diaphragm wall support according to claim 2, characterized in that: One set of the temperature measuring condenser tubes (202) is arranged between the temperature measuring conduit (201) near the front and the temperature measuring conduit (201) in the middle, and the other set of temperature measuring condenser tubes (202) is arranged between the temperature measuring conduit (201) near the rear and the temperature measuring conduit (201) in the middle, and the two sets of temperature measuring condenser tubes (202) are arranged symmetrically.

4. The concrete temperature measuring device for diaphragm wall support according to claim 3, characterized in that: The inner diameter of the zigzag-shaped temperature measuring condenser tube (202) is 28mm. The vertical distance between the horizontal pipe sections (212) in the temperature measuring condenser tube (202) is 2m, and the horizontal distance between the vertical pipe sections (222) is 1m. The temperature measuring conduit tube (201) and the temperature measuring condenser tube (202) are welded to the positions where they contact the underground continuous wall reinforcement.

5. The concrete temperature measuring device for diaphragm wall support according to claim 4, characterized in that: The three temperature measuring points (203) on each of the temperature measuring conduits (201) are respectively arranged in the middle of the wall, 1000mm from the bottom of the underground continuous wall and 2000mm from the bottom of the crown beam in the vertical direction, and respectively arranged in the middle of the wall, 100mm from one side edge and 1000mm from one side edge in the horizontal direction.

6. The concrete temperature measuring device for diaphragm wall support according to claim 5, characterized in that: A reference observation hole is set up on one side of the diaphragm wall in the foundation pit. A soil temperature measuring pipe is installed in the reference observation hole, and soil temperature measuring points (204) are set up on it to observe the soil temperature at the same time.

7. The concrete temperature measuring device for diaphragm wall support according to claim 6, characterized in that: The top end of the temperature measuring wire is fixed with a tie wire, and the bottom is fixed to the temperature measuring conduit with a nylon rope. The temperature measuring conduit (201) is filled with cement slurry with the same mix ratio as the poured concrete.

Images