Carbon dioxide reinforced calcareous sand unit test device
By designing a carbon dioxide-reinforced calcareous sand unit test device, the CO2-water-calcium carbonate reaction was simulated, solving the liquefaction problem of calcareous sand foundation, providing a theoretical basis for the laboratory reinforcement effect, and optimizing the engineering performance of calcareous sand foundation.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-29
- Publication Date
- 2026-04-03
AI Technical Summary
Existing calcareous sand foundations are prone to liquefaction under dynamic loads. Traditional reinforcement techniques are ineffective and unsuitable for marine environments. In particular, microbial-induced sedimentation techniques are unstable and cannot meet engineering requirements.
Design a unit test device for carbon dioxide-reinforced calcareous sand, including a reaction vessel, a thermal control system, a CO2 injection system, and a pressure control system, to simulate the CO2-water-calcium carbonate reaction, study the feasibility of CO2-reinforced calcareous sand, and conduct wave velocity, compressive strength, and permeability tests.
Precise research on the CO2 reinforcement effect under laboratory conditions provides a theoretical basis for on-site construction, saves costs, prevents construction problems, and optimizes the engineering performance of calcareous sand foundations.
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Figure CN121784262A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of geotechnical engineering foundation treatment technology, and in particular to a carbon dioxide-reinforced calcareous sand unit test device. Background Technology
[0002] The South my country Sea contains abundant calcareous sand, a type of marine sediment rich in calcium carbonate or other insoluble carbonates. Due to its brittle particle structure, it is prone to breakage under stress, exhibiting mechanical properties different from conventional terrigenous sand. With the development of coral reef engineering geological activities, calcareous sand foundations are crucial for artificial reclamation during island and reef construction. However, they are susceptible to liquefaction under dynamic loads such as waves or earthquakes. This liquefaction problem causes calcareous sand foundations to fail to meet settlement and bearing capacity requirements, necessitating reinforcement treatment.
[0003] The construction of islands and reefs takes place in the open ocean, and given the unique engineering mechanical properties of calcareous sand, methods for optimizing its engineering performance and improving its foundation are limited. Currently, the main technologies for reinforcing calcareous sand foundations are vibro-compaction or dynamic compaction, cement grouting, and microbial-induced calcium carbonate precipitation. However, vibro-compaction or dynamic compaction suffers from issues such as uneven treatment depth or post-treatment foundation uniformity, and the fragility of calcareous sand under mechanical force. Microbial-induced precipitation technology faces challenges in marine environments, including low microbial survival rates, low reactant conversion rates, and, most importantly, the inability to maintain treatment effectiveness long-term.
[0004] To address the aforementioned issues, a novel calcareous sand foundation reinforcement technology needs to be developed. CCUS (Carbon Dioxide Sequestration System) technology is considered a key technology for reducing CO2 emissions during fossil fuel power generation and industrial production. Its CO2 geological sequestration technology involves injecting CO2 into a geological body, where a CO2-water-rock reaction and mineral dissolution / precipitation occur, storing CO2 in adsorbed, free, water-soluble, and mineralized forms. To investigate whether CO2 geological sequestration technology can be used for calcareous CO2 sand foundation reinforcement, model tests of CO2-reinforced calcareous sand foundations need to be conducted. These tests will investigate the CO2-water-calcium carbonate reaction and calcium carbonate dissolution / precipitation to mechanistically confirm the feasibility of CO2-reinforced calcareous sand. Then, wave velocity tests, uniaxial compressive strength tests, triaxial compression tests, and permeability tests will be performed on CO2-reinforced calcareous sand samples to study their engineering mechanical properties. Finally, model tests of CO2-reinforced calcareous sand foundations will be conducted. Therefore, developing a unit test device for CO2-reinforced calcareous sand reinforcement is a primary task. Summary of the Invention
[0005] In view of this, the present invention provides a unit test device for carbon dioxide reinforcement of calcareous sand, which can help to accurately study the effects of CO2 injection method, injection depth, injection pressure and duration on reinforcement depth and reinforcement radius. Based on the test results and proportional principles, a process flow and process parameter design method for CO2 reinforcement technology of calcareous sand foundation can be preliminarily established for reference in actual engineering.
[0006] To achieve the above objectives, the present invention adopts the following technical solution:
[0007] A carbon dioxide-reinforced calcareous sand unit test device is provided, which consists of a reaction vessel, a reaction vessel heating and cooling control system, a CO2 injection system, and a pressure control system. The reaction vessel jacket cooling and heating device is used to heat or cool the reaction vessel, the CO2 injection system introduces CO2 gas into the reaction vessel, and the pressure control system is used to monitor and control the pressure inside the reaction vessel.
[0008] Preferably, the reactor's heating and cooling control system includes a heating device, a cooling device, a heating and cooling jacket, a temperature measuring element, and a temperature setting panel;
[0009] The heating and cooling jacket is fitted on the lower middle part of the outer wall of the reactor; the heating and cooling jacket contains a fluid medium, which is heated or cooled by a heating device or a cooling device and then circulated to the heating and cooling jacket to heat or cool the reactor.
[0010] The temperature measuring element is located at the inner top of the reaction vessel;
[0011] The heating device, cooling device, and temperature measuring element are all electrically connected to the temperature setting panel.
[0012] Preferably, the reactor's heating and cooling control system controls the temperature inside the reactor to vary between 0 and 100°C.
[0013] Preferably, the CO2 injection system includes a gas tank, an injection pump, a flow controller, an injection valve, a main pipe, and branch pipes; the branch pipes include multiple conduits inserted into the reactor at different depths, each conduit being equipped with an injection valve, and the conduits being connected to the main pipe through the injection valves.
[0014] Preferably, multiple catheters are arranged in a uniformly decreasing pattern from deep to shallow, and the diameter of the catheters is 2-4 mm.
[0015] Preferably, the pressure control system includes a pressure control valve and a pressure measuring element. The pressure control valve is located on the main pipe of the CO2 injection system, and the pressure measuring element is located at the top inside the reactor.
[0016] Preferably, the pressure control system controls the pressure inside the reactor to be between 4 and 150 bar.
[0017] The beneficial effects of this invention are:
[0018] 1. Under laboratory conditions, the effect of calcareous sand reinforcement can be accurately simulated, providing valuable theoretical and practical experience for on-site construction.
[0019] 2. Saves on-site testing costs and allows for proactive solutions to potential problems during the construction phase. Attached Figure Description
[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.
[0021] Figure 1 This is a schematic diagram of a carbon dioxide-reinforced calcareous sand unit test device provided by the present invention. Detailed Implementation
[0022] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0023] Example 1
[0024] like Figure 1 As shown, this embodiment provides a carbon dioxide-reinforced calcareous sand unit test device, which consists of a reaction vessel 1, a reaction vessel heating and cooling control system 2, a CO2 injection system 3, and a pressure control system 4;
[0025] The reactor's heating and cooling control system includes a heating device 21, a cooling device 22, a heating and cooling jacket 23, a temperature measuring element 24, and a temperature setting panel 25;
[0026] The hot and cold jacket 23 is fitted on the lower middle part of the outer wall of the reactor 1; the hot and cold jacket 23 contains a fluid medium, which is heated or cooled by the heating device 21 or the cooling device 22 and then circulated to the hot and cold jacket 23 to heat or cool the reactor 1.
[0027] Temperature measuring element 24 is located at the top inside of reactor 1;
[0028] The heating device 21, cooling device 22 and temperature measuring element 24 are all electrically connected to the temperature setting panel 25;
[0029] The reactor heating and cooling control system 2 controls the temperature inside reactor 1 to vary between 0 and 100℃.
[0030] CO2 injection system 3 includes a gas tank 31, an injection pump 32, a flow controller 33, an injection valve 34, a main pipe 35, and a branch pipe 36; the branch pipe 36 includes multiple conduits inserted into the reactor 1 at different depths, each conduit is equipped with an injection valve 34, and the conduit is connected to the main pipe 35 through the injection valve 34.
[0031] Multiple ducts are arranged in a uniformly decreasing pattern from deep to shallow.
[0032] The pressure control system 4 includes a pressure control valve 41 and a pressure measuring element 42. The pressure control valve 41 is located on the main pipe 35 of the CO2 injection system 3, and the pressure measuring element 24 is located at the inner top of the reactor 1.
[0033] The experimental method using the experimental apparatus of this invention is as follows: First, a mixture of calcareous sand and water is filled into the reaction vessel 1. The weight percentage of water in the mixture can be 10%, 20%, or 30%. Then, CO2 gas is introduced into the gas tank 31 by turning on the gas source. The injection pump 32 is turned on, and CO2 is injected into the reaction vessel 1 through the main pipe 35. The flow rate is controlled by the flow controller 33 on the main pipe. The cold bath circulation is turned on. When the pressure value reaches the set value and stabilizes, the injection pump is turned off, and the system temperature is set to induce the forward reaction of CO2-water-calcareous sand, dissolving calcium carbonate. The changes in the pressure and volume of the gas in the system are recorded in real time. When the pressure stabilizes, the calcium carbonate dissolution process ends. The current pressure and temperature are the pressure and temperature at which calcium carbonate dissolution and precipitation reach equilibrium. The system temperature is increased to induce the reverse reaction of CO2-water-calcareous sand, and calcium carbonate precipitates. When the system pressure stabilizes, the calcium carbonate precipitation process ends. The current pressure and temperature are the pressure and temperature at which calcium carbonate dissolution and precipitation reach equilibrium again. The compression and shear wave velocities of the sample in the reaction vessel are measured using a bending element timer to monitor the entire reaction process. Once the pressure and temperature settings stabilize, the calcareous sand solid is initially formed, and the compressive strength and shear pressure tests of the samples can be performed.
[0034] By repeatedly conducting experiments with different combinations of pressure and temperature, the temperature and pressure boundaries for calcium carbonate dissolution / precipitation (forward / reverse reaction) can be obtained.
[0035] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.
[0036] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. A carbon dioxide-reinforced calcareous sand unit test apparatus, characterized in that, The device consists of a reaction vessel, a reaction vessel heating and cooling control system, a CO2 injection system, and a pressure control system. The reaction vessel jacket cooling and heating equipment is used to heat or cool the reaction vessel, the CO2 injection system introduces CO2 gas into the reaction vessel, and the pressure control system is used to monitor and control the pressure inside the reaction vessel.
2. The carbon dioxide-reinforced calcareous sand unit test device according to claim 1, characterized in that, The reactor's heating and cooling control system includes a heating device, a cooling device, a heating and cooling jacket, a temperature measuring element, and a temperature setting panel. The heating and cooling jacket is fitted on the lower middle part of the outer wall of the reactor; the heating and cooling jacket contains a fluid medium, which is heated or cooled by a heating device or a cooling device and then circulated to the heating and cooling jacket to heat or cool the reactor. The temperature measuring element is located at the inner top of the reaction vessel; The heating device, cooling device, and temperature measuring element are all electrically connected to the temperature setting panel.
3. The carbon dioxide-reinforced calcareous sand unit test device according to claim 1, characterized in that, The reactor's heating and cooling control system controls the temperature inside the reactor to vary between 0 and 100°C.
4. The carbon dioxide-reinforced calcareous sand unit test device according to claim 1, characterized in that, The CO2 injection system includes a gas tank, an injection pump, a flow controller, an injection valve, a main pipe, and branch pipes; the branch pipes include multiple conduits inserted into the reactor at different depths, each conduit being equipped with an injection valve, and the conduits being connected to the main pipe through the injection valves.
5. The carbon dioxide-reinforced calcareous sand unit test device according to claim 4, characterized in that, Multiple catheters are arranged in a uniformly decreasing pattern from deep to shallow, and the diameter of the catheters is 2-4 mm.
6. The carbon dioxide-reinforced calcareous sand unit test device according to claim 4, characterized in that, The pressure control system includes a pressure control valve and a pressure measuring element. The pressure control valve is located on the main pipe of the CO2 injection system, and the pressure measuring element is located at the top inside the reactor.
7. The carbon dioxide-reinforced calcareous sand unit test device according to claim 1, characterized in that, The pressure control system controls the pressure inside the reactor to be between 4 and 150 bar.