A method for temperature control of cast-in-place concrete of raft foundation

Abstract

The application discloses a cast-in-situ concrete temperature regulation method of a raft foundation, the raft foundation is provided with a raft body, a post-pouring belt structure and a temperature regulation component, the temperature regulation component is arranged in the raft body on the two sides of the post-pouring belt structure, and the temperature regulation component comprises a temperature measuring device, a water pump, an internal circulation water pipe, a water outlet pipe and a water inlet pipe; the post-pouring belt support pipe, the water inlet pipe and the water outlet pipe are integrally arranged, the construction space is reduced, and the temperature regulation is carried out in cooperation with the stress condition of the post-pouring belt and the concrete temperature detection condition; the internal temperature measuring device is arranged, the comparative temperature values can be obtained at multiple angles, the temperature monitoring effect of the mass concrete is maximally ensured, and the crack formation of the concrete caused by hydration heat is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of mass concrete pouring, in particular to a raft foundation cast-in-place concrete temperature regulation method. BACKGROUND

[0002] The mass raft foundation is widely used in building foundation, which is shallow and wide, can bear the load of the ground, and uniformly transmit the load to the foundation. Since the hydration heat generated during the pouring of the large raft foundation is large, the construction generally adopts layered pouring or sets a pouring slope for controlling the hydration heat of the concrete. The time interval between layers needs to be increased to ensure that the initial setting time is before the previous layer, which increases the initial setting time. There are also methods of reducing the temperature difference between the inside and outside by adding cooling water pipes in the concrete. Due to the large volume of the raft foundation and the large hydration heat, it is difficult to control the temperature of the mass concrete during general construction, especially for the position of the post-pouring belt. SUMMARY

[0003] The purpose of the present application is to provide a raft foundation cast-in-place concrete temperature regulation method to solve the problems in the background art.

[0004] In order to solve the above technical problems, the present application provides the following technical scheme: a raft foundation cast-in-place concrete temperature regulation method, the raft foundation is provided with a raft body, a post-pouring belt structure and a temperature regulation assembly, the temperature regulation assembly is arranged inside the raft body on both sides of the post-pouring belt structure, the temperature regulation assembly includes a temperature measuring device, a water pump, an internal circulation water pipe, an outlet pipe and an inlet pipe; characterized in that: the post-pouring belt structure is provided with a post-pouring belt formwork, which is supported by a support steel pipe in the middle of the formwork, the support steel pipe is provided with an upper layer support steel pipe, a middle layer support steel pipe and a lower layer support steel pipe, the two ends of the upper layer support steel pipe are connected to the inlet pipes on both sides through flange pipes and are tightened to the formwork, the two ends of the lower layer support steel pipe are connected to the outlet pipes on both sides through flange pipes and are tightened to the formwork, the inlet pipe is connected to the inlet water pump, and the outlet pipe is connected to the drainage pipe; the temperature measuring device is intermittently arranged on the internal circulation water pipe;

[0005] The internal circulation water pipe includes horizontal steel pipes and vertical steel pipes arranged according to the volume of the concrete, and the arrangement mode is dense in the middle and sparse on the outside.

[0006] The support steel pipe of the post-pouring belt is provided with a stress detection device, the stress detection device tests the initial stress F0 of the upper layer support steel pipe, the middle layer support steel pipe and the lower layer support steel pipe, and when the stress is abnormal, the temperature change of the temperature measuring device is observed, and when the temperature rises obviously, the cooling operation is performed, the cold water is introduced into the raft body through the inlet pipe by the water pump to regulate the temperature; so that the instantaneous stress F of the support steel pipe is maintained within 110% of the initial stress F0.

[0007] When the stress is abnormal and increases, immediately perform a cooling operation, with the temperature measuring device counting every 5 minutes; when the stress is abnormal and decreases, check the flange of the supporting steel pipe, tighten the flange at the template, and restore its stress to the initial value.

[0008] The supporting steel pipe of the post-cast strip is the same size as the internal circulating water pipe. The supporting steel pipe is made of 304 stainless steel. The outlet pipe and the inlet pipe are both made of 304 stainless steel. The internal circulating water pipe is made of thin steel pipe. They are connected as a whole by seamless welding. The pipe diameter is 50mm-80mm.

[0009] The upper support steel pipe has threads at both ends, and the threads on both sides of the upper support steel pipe correspond to the connections of two water inlet pipes. The water inlet pipes are equipped with waterproof gaskets. The first flange pipe includes a first fixed end and a first movable end. The first fixed end is fixedly connected to the threaded interface of the water inlet pipe, and its first movable end is connected to the threaded opening of the upper support steel pipe. The lower support steel pipe has threads at both ends, and the threads on both sides of the lower support steel pipe correspond to the connections of two water outlet pipes. The water outlet pipes are equipped with waterproof gaskets. The second flange pipe includes a second fixed end and a second movable end. The second fixed end is fixedly connected to the threaded interface of the water outlet pipe, and its second movable end is connected to the threaded opening of the lower support steel pipe.

[0010] When it is necessary to tighten the flange at the template, the stress is restored to the initial value by rotating the first movable end and the second movable end.

[0011] The bottom of the post-pouring strip template is provided with a waterstop, which extends to the bottom of the raft body on both sides.

[0012] The estimated temperature T of the concrete in the raft foundation h Calculated according to the formula:

[0013] T h =(mc+KF)Q(1-e -mt ) / cp

[0014] Among them, T h It is the maximum adiabatic temperature rise of concrete (°C), and mc is the temperature rise of concrete in... Cement The dosage of concrete active admixture is (kg / m3), F is the dosage of concrete active admixture (kg / m3), K is the admixture reduction factor, Q is the heat of hydration of cement at 28 days (kJ / kg), c is the specific heat of concrete (kJ / kg.K), p is the density of concrete (kg / m3), e is a constant (taken as 2.718), m is a coefficient related to cement type and pouring temperature, and t is the concrete age (d).

[0015] The formula for calculating the stress value σ of the concrete within the raft foundation is as follows:

[0016] σ = E alpha delta T; wherein, sigma represents stress, E is the modulus of elasticity, alpha is the thermal expansion coefficient, and delta T is the temperature change;

[0017] When the average temperature T0 of the real side point is greater than the estimated temperature T h 120%, the cooling operation is started, so that the stress value sigma meets the specification requirements.

[0018] Compared with the prior art, the application has the beneficial effects:

[0019] (1), by setting the integrally supported post-cast strip support pipe, water inlet pipe and water outlet pipe, the construction space is reduced, and the stress condition of the post-cast strip and the concrete temperature detection condition are adjusted and controlled.

[0020] (2), due to the setting of the internal temperature measuring device, the temperature value can be compared at multiple angles, the temperature monitoring effect of mass concrete is maximized, and the formation of cracks in the concrete caused by hydration heat is reduced.

[0021] (3), the application is arranged in an internal circulation water pipe, the water inlet is arranged at the upper side, the water outlet is arranged at the lower side, and the post-cast strip support pipe is used, which is beneficial to the rapid exchange of cold water. DETAILED DESCRIPTION

[0022] The accompanying drawings are included to provide a further understanding of the application, and constitute a part of the specification, and are used to explain the application together with embodiments of the application, and do not constitute a limitation on the application. In the drawings:

[0023] Figure 1 is the raft foundation temperature regulation layout of the application;

[0024] Figure 2 is the raft foundation plan view of the application;

[0025] Figure 3 is the support steel pipe schematic view of the application;

[0026] Figure 4 is the support-free steel pipe connection view of the application.

[0027] In the figure: 1, raft body; 2, post-cast strip structure; 21, post-cast strip formwork; 22, support steel pipe; 221, upper layer support steel pipe; 222, middle layer support steel pipe; 223, lower layer support steel pipe; 23, stress detection device; 3, temperature regulation assembly; 31, temperature measuring device; 32, water pump; 33, internal circulation water pipe; 34, water outlet pipe; 35, water inlet pipe; 331, transverse steel pipe; 332, longitudinal steel pipe; 2211, first waterproof gasket; 2212, first flange pipe; 2213, first fixed end; 2214, first movable end; 2231, second waterproof gasket; 2232, second flange pipe; 2233, second fixed end; 2234, second movable end; 24, bottom mold; 25, water stop. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0029] A cast-in-situ concrete temperature regulation method for a raft foundation, the raft foundation is provided with a raft body (1), a post-cast strip structure (2) and a temperature regulation assembly (3), the temperature regulation assembly is arranged inside the raft body on both sides of the post-cast strip structure, and the temperature regulation assembly comprises a temperature measuring device (31), a water pump (32), an internal circulation water pipe (33), a water outlet pipe (34) and a water inlet pipe (35); characterized in that: the post-cast strip structure (2) is provided with a post-cast strip formwork (21), the post-cast strip formwork is supported in the middle by a support steel pipe (22), the support steel pipe is provided with an upper layer support steel pipe (221), a middle layer support steel pipe (222) and a lower layer support steel pipe (223), both ends of the upper layer support steel pipe are connected to the water inlet pipes on both sides through flange pipes and are screwed to the formwork, both ends of the lower layer support steel pipe are connected to the water outlet pipes on both sides through flange pipes and are screwed to the formwork, the water inlet pipes are connected to the water inlet pump (32), and the water outlet pipes are connected to a drainage pipeline; the temperature measuring devices are intermittently arranged on the internal circulation water pipe;

[0030] Preferably, both ends of the middle layer support steel pipe (222) directly support the formwork, and the support spacing is adjustable.

[0031] The internal circulation water pipe (33) comprises transverse steel pipes (331) and longitudinal steel pipes (332) arranged according to the volume of the concrete, and the arrangement mode is that the middle is dense and the outside is sparse.

[0032] The support steel pipe (22) of the post-cast strip is provided with a stress detection device (23), which tests the initial stress F0 of the upper layer support steel pipe, the middle layer support steel pipe and the lower layer support steel pipe. When the stress is abnormal, the temperature change of the temperature observation device is observed. When the temperature rises obviously, the temperature control is performed by the water pump to enter the raft body through the water inlet pipe. The instantaneous stress F of the support steel pipe is maintained within 110% of the initial stress F0.

[0033] As preferred, when the stress is abnormal, the temperature control is directly performed. The temperature observation device counts every 5 minutes. When the stress is reduced, the flange of the support steel pipe is checked. The flange of the template is tightened to restore the stress to the initial value.

[0034] As preferred, the support steel pipe of the post-cast strip is consistent with the size of the internal circulating water pipe. The support steel pipe is made of 304 stainless steel pipe. The water outlet pipe and the water inlet pipe are made of 304 stainless steel pipe. The internal circulating water pipe is made of thin steel pipe. The seamless welding connection is integrated into a whole. The pipe diameter is 50mm-80mm.

[0035] As preferred, the two ends of the upper layer support steel pipe (221) are provided with threads. The threads on both sides of the upper layer support steel pipe correspond to the connection of two water inlet pipes. The water inlet pipe is provided with a first waterproof gasket (2211). The first flange pipe (2212) includes a first fixed end (2213) and a first movable end (2214). The first fixed end is fixedly connected with the threaded interface of the water inlet pipe. The first movable end is connected with the threaded port of the upper layer support steel pipe. The two ends of the lower layer support steel pipe (223) are provided with threads. The threads on both sides of the lower layer support steel pipe correspond to the connection of two water outlet pipes. The water outlet pipe is provided with a second waterproof gasket (2231). The second flange pipe (2232) includes a second fixed end (2233) and a second movable end (2234). The second fixed end is fixedly connected with the threaded interface of the water outlet pipe. The second movable end is connected with the threaded port of the lower layer support steel pipe.

[0036] As preferred, when the flange of the template needs to be tightened, the stress is restored to the initial value by rotating the first movable end and the second movable end.

[0037] The bottom of the post-cast strip template is provided with a bottom die 24 and a water stop 25. The water stop extends to the bottom of the raft body on both sides.

[0038] As preferred, the estimated temperature T of the internal concrete of the raft foundation is calculated according to the formula: h According to the formula:

[0039] T h =(mc+KF)Q(1-e -mt) / cp

[0040] Among them, T h It is the maximum adiabatic temperature rise of concrete (°C), and mc is the temperature rise of concrete in... Cement The dosage of concrete is (kg / m3), F is the dosage of active admixture in concrete (kg / m3), K is the admixture reduction factor, Q is the heat of hydration of cement at 28 days (kJ / kg), c is the specific heat of concrete (kJ / kg K), p is the density of concrete (kg / m3), e is a constant (taken as 2.718), m is a coefficient related to cement type and pouring temperature, and t is the age of concrete (d).

[0041] The stress value σ in the concrete within the raft foundation is calculated using the following formula:

[0042] σ = EαΔT; where σ represents stress, E is the elastic modulus, α is the coefficient of thermal expansion, and ΔT is the temperature change;

[0043] When the average temperature T0 at the actual measurement point is greater than 120% of the estimated temperature Th, the cooling operation is initiated so that the stress value σ meets the specification requirements.

[0044] During construction, the bottom of the raft slab is poured first, and the waterstop structure is installed. After the formwork support for the post-pouring strip is completed, the reinforcing steel bars inside the raft slab are installed, and the temperature control components are installed. The internal circulating water pipes include horizontal and vertical steel pipes arranged according to the concrete volume, with a denser arrangement in the middle and a sparser arrangement on the outside. At the same time, the temperature measuring devices should be evenly spaced and tied to the reinforcing steel bars, taking care not to let the temperature measuring joints come into contact with the reinforcing steel bars. After completing the layout of the internal circulating water pipes, the positions of the inlet and outlet are ensured to be reasonable. The pipes are then installed in conjunction with the supporting steel pipes to ensure the fixed requirements of the flange pipes supporting the formwork of the post-pouring strip.

[0045] When monitoring concrete temperature control, stress changes and temperature changes can be observed for dual monitoring. When an abnormality occurs in the stress, the temperature change of the temperature measuring device can be observed. If the temperature rises significantly, a cooling operation can be carried out by pumping cold water into the raft body through the inlet pipe to regulate the temperature. This ensures that the instantaneous stress F of the supporting steel pipe is maintained within 110% of the initial stress F0.

[0046] During construction, pouring can be done in layers or quickly. When pouring in layers, the number of water circulation cycles can be reduced appropriately. During quick pouring, when the temperature difference between the inside and outside of the concrete reaches 10°C, the circulation of cooling water can be accelerated, and a warning should be issued to the on-site personnel to speed up the finishing process. An alarm should be triggered immediately when the temperature difference reaches 20°C. The inlet and outlet water flow of the cooling water pipes should be strictly tested, and the inlet and outlet water temperature difference should be ensured to be less than or equal to 10°C by adjusting the water flow rate and volume. Temperature records should be monitored, and the water flow adjusted according to the temperature situation to ensure that the temperature change rate does not exceed 2°C / day.

[0047] The temperature measuring device uses the method of leaving temperature measuring holes or pre-embedded temperature strain gauges. The concrete temperature measurement start time: from the start of the concrete into the mold to the concrete reaching the critical strength of freezing, every 2h is measured once, and the outdoor temperature and the surrounding environment temperature are measured three to four times per day. All temperature measuring holes and points are numbered, and the measurement results are written into the official records by the field test personnel. When using temperature measuring holes to measure temperature, the hole is plugged with insulation material around the hole, and the thermometer should be left in the temperature measuring hole for more than 3 minutes before reading. The temperature measurement method of the temperature strain gauge is described in the temperature strain gauge specification; if the concrete temperature is found to be too high or too low, the relevant personnel should be notified immediately and effective measures should be taken in time. The concrete reaches the critical strength; the surface temperature of the concrete cools to 5℃ and the temperature difference between the surface temperature of the concrete after the formwork is removed and the ambient temperature is ≤20℃; the temperature of the temperature measuring hole and the atmospheric temperature are close; the above conditions are met to end the temperature measurement of the concrete member. After the formwork of the raft body is removed, the post-pouring strip support pipe is also removed and the post-pouring strip construction is carried out, and the entire raft foundation construction is completed.

[0048] It should be noted that the relational terms herein such as first and second and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any such actual relationship or order between such entities or actions. Moreover, the terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0049] Finally, it should be noted that: the above only describes the preferred embodiments of the present application, and is not used to limit the present application, although the foregoing embodiments of the present application are described in detail, for those skilled in the art, the technical solutions recorded in the foregoing embodiments can be modified, or some technical features can be replaced. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for controlling the temperature of cast-in-place concrete in a raft foundation, wherein the raft foundation comprises a raft body (1), a post-cast strip structure (2), and a temperature control component (3), wherein the temperature control component is disposed inside the raft body on both sides of the post-cast strip structure, and the temperature control component includes a temperature measuring device (31), a water pump (32), an internal circulating water pipe (33), an outlet pipe (34), and an inlet pipe (35); characterized in that: The post-cast strip structure (2) is provided with a post-cast strip template (21). The post-cast strip template is supported in the middle by a supporting steel pipe (22). The supporting steel pipe is provided with an upper supporting steel pipe (221), a middle supporting steel pipe (222), and a lower supporting steel pipe (223). The two ends of the upper supporting steel pipe are connected to the water inlet pipes on both sides through flange pipes and tightened to the template. The two ends of the lower supporting steel pipe are connected to the water outlet pipes on both sides through flange pipes and tightened to the template. The water inlet pipe is connected to the water inlet pump (32), and the water outlet pipe is connected to the drainage pipe. The temperature measuring device is intermittently installed on the internal circulating water pipe. The internal circulating water pipe includes horizontal and vertical steel pipes arranged according to the concrete volume, with the density of the pipes arranged in a way that is denser in the middle and sparser on the outside. The feature is that: stress detection devices are installed on the supporting steel pipes of the post-cast strip, and the stress detection devices test the initial stress of the upper supporting steel pipe, the middle supporting steel pipe and the lower supporting steel pipe. The size of the stress is monitored, and when abnormal stress occurs, the temperature change of the temperature measuring device is observed. If the temperature rises significantly, a cooling operation is performed by pumping cold water into the raft body through the inlet pipe to regulate the temperature; this reduces the instantaneous stress on the supporting steel pipe. All maintained at initial stress Within 110%; When the stress is abnormal and increases, immediately perform a cooling operation, with the temperature measuring device counting every 5 minutes; when the stress is abnormal and decreases, check the flange of the supporting steel pipe, tighten the flange at the template, and restore its stress to the initial value.

2. The method for controlling the temperature of cast-in-place concrete in a raft foundation according to claim 1, characterized in that: The supporting steel pipe of the post-cast strip is the same size as the internal circulating water pipe. The supporting steel pipe is made of 304 stainless steel. The outlet pipe and the inlet pipe are both made of 304 stainless steel. The internal circulating water pipe is made of thin steel pipe. They are connected as a whole by seamless welding. The pipe diameter is 50mm-80mm.

3. The method for controlling the temperature of cast-in-place concrete in a raft foundation according to claim 2, characterized in that: The upper support steel pipe (221) has threads at both ends, and the threads on both sides of the upper support steel pipe correspond to the connection of two water inlet pipes. The water inlet pipe is equipped with a first waterproof gasket (2211). The first flange pipe (2212) includes a first fixed end (2213) and a first movable end (2214). The first fixed end is fixedly connected to the threaded interface of the water inlet pipe, and its first movable end is connected to the threaded port of the upper support steel pipe. The lower support steel pipe (223) has threads at both ends, and the threads on both sides of the lower support steel pipe correspond to the connection of two water outlet pipes. The water outlet pipe is equipped with a second waterproof gasket (2231). The second flange pipe (2232) includes a second fixed end (2233) and a second movable end (2234). The second fixed end is fixedly connected to the threaded interface of the water outlet pipe, and its second movable end is connected to the threaded port of the lower support steel pipe.

4. The method for controlling the temperature of cast-in-place concrete in a raft foundation according to claim 2, characterized in that: When it is necessary to tighten the flange at the template, the stress is restored to the initial value by rotating the first movable end and the second movable end.

5. The method for controlling the temperature of cast-in-place concrete in a raft foundation according to claim 2, characterized in that: The bottom of the post-pouring strip template is provided with a bottom mold (24) and a waterstop (25), and the waterstop extends to the bottom of the raft body on both sides.

6. The method for controlling the temperature of cast-in-place concrete in a raft foundation according to claim 2, characterized in that: The estimated temperature of the concrete inside the raft foundation Calculated according to the formula: in, It is the maximum adiabatic temperature rise of concrete. It refers to the amount of cement used in concrete. This refers to the dosage of active admixtures in concrete. It is the reduction factor for admixtures. It is the heat of hydration of cement over 28 days. It is the specific heat of concrete. It is the density of concrete. It is a constant. It is a coefficient related to the type of cement and the temperature during pouring. It refers to the age of the concrete; The stress value of the concrete within the raft foundation Calculated according to the formula: ;in, Indicates stress, It is the elastic modulus. It is the coefficient of thermal expansion. This is the maximum adiabatic temperature rise of concrete; When the average temperature of the real point Greater than the estimated temperature When the stress value reaches 120%, a cooling operation is initiated to reduce the stress value. Meets the requirements of the specifications.

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