CN113899671A - Flexible wall penetration test method for temperature-stress integrated control under dry-wet cycle - Google Patents

Flexible wall penetration test method for temperature-stress integrated control under dry-wet cycle Download PDF

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CN113899671A
CN113899671A CN202111048565.3A CN202111048565A CN113899671A CN 113899671 A CN113899671 A CN 113899671A CN 202111048565 A CN202111048565 A CN 202111048565A CN 113899671 A CN113899671 A CN 113899671A
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chamber
pressure
injection
test
liquid
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CN113899671B (en
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查甫生
秦皓
许龙
孙献国
康博
周阳
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Anhui Huizi Construction Engineering Co ltd
Anhui Urban Construction Foundation Engineering Co ltd
Hefei University of Technology
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Anhui Huizi Construction Engineering Co ltd
Anhui Urban Construction Foundation Engineering Co ltd
Hefei University of Technology
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume, or surface-area of porous materials
    • G01N15/08—Investigating permeability, pore-volume, or surface area of porous materials
    • G01N15/082—Investigating permeability by forcing a fluid through a sample
    • G01N15/0826—Investigating permeability by forcing a fluid through a sample and measuring fluid flow rate, i.e. permeation rate or pressure change
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E30/00—Energy generation of nuclear origin
    • Y02E30/30—Nuclear fission reactors

Abstract

The invention provides a flexible wall penetration test method for temperature-stress integrated control under dry-wet circulation, and relates to the field of geotechnical engineering geotechnical tests. The test method comprises the steps of dry-humidity circulation, axial pressure application, bubble removal, penetration test and the like, and can obtain a large amount of data about soil body pressure-deformation-penetration by performing a series of penetration tests on different samples, such as different dry-wet circulation times, different test temperatures, different consolidation pressures, different injection air pressures, different injection confining pressures and the like, thereby realizing the determination of the penetration coefficient under a plurality of influence factors, making up the defects of the existing flexible wall penetration test, and saving more labor and time.

Description

Flexible wall penetration test method for temperature-stress integrated control under dry-wet cycle
Technical Field
The invention relates to the field of geotechnical engineering geotechnical tests, in particular to a flexible wall penetration test method for temperature-stress integrated control under dry-wet circulation.
Background
In the 21 st century, the construction of engineering projects is continuously promoted in China, the stable development of economic society is promoted, and some engineering geological problems are often encountered in the construction process. The permeability coefficient is a quantitative index representing the permeability of soil, and is also a basic parameter which must be measured in engineering application. Meanwhile, under the actual conditions, external factors such as dry-wet circulation, temperature change, stress change and the like caused by humidity change can cause different influences on the permeability of the rock-soil body, so that the permeability coefficient of the soil body under the dry-wet circulation, the temperature and the stress change is obtained, the field environment is truly simulated, the key problem of deeply knowing the mechanism of the influence of soil body crack development on the seepage action is solved, and the important work for engineering project construction is also served.
In order to consider external influences in a penetration test, an article entitled "improving permeability and pore structure of a separation wall under dry-wet/freeze-thaw action", Liu Lin, Zhang Yongpeng, "a building material school newspaper" indicates a test method, a TST-55 type rigid wall soil permeameter is adopted to carry out the penetration test, the method can simply and conveniently measure the permeability coefficient, but the proposed test method does not consider the phenomenon that the sample cannot be tightly contacted with the side wall due to dry-wet deformation, improper installation and other factors, side leakage occurs, the permeability coefficient of a soil body cannot be accurately measured, meanwhile, the temperature in the actual environment, the influence on the permeability of the material when stress conditions and penetrating fluid are heavy metal liquid, organic pollution liquid, strong acid and strong base are not considered, the measurement process needs manual operation, and the process is complicated.
Entitled "Effect of pore fluid and wet-cycle on structure and Hydraulic compliance of the day", Thyagara T, Juulina M. "Geotechnique Letters", 2019, 9 (4): 348- ("influence of pore fluid and dry-wet circulation on clay structure and water conductivity"; Kuai Shu, 9, vol. 9, No. 4, page 348- & 354) proposes a test method, which can simulate stress influence under actual conditions by adopting a consolidated rigid wall penetration method, but the test method does not consider the phenomenon that the sample cannot be in close contact with the side wall due to dry-wet deformation, improper installation and other factors, and causes side leakage, so that the permeability coefficient of the soil body cannot be accurately measured, and also does not consider the influence of temperature and penetrating fluid in the actual environment on material permeability when the temperature and the penetrating fluid are heavy metal fluid, organic polluted fluid, strong acid and strong base, and the measurement process needs manual operation and is complicated.
Entitled "Cracking and water seal of used as planar coverage under-drying cycles", Lu H, Li J, Wang W, Wang C. "Environmental Earth Sciences", 2015, 74 (11): 1-10. ("cracking and water seepage of loess from lower Sichuan under wet and dry cycles as a landfill cover"; environmental Earth science, vol. 74, p. 11, 173-, the method can effectively avoid the leakage phenomenon of the liquid side wall and accurately measure the permeability coefficient, but has the premise that the material is integrally installed in an instrument, the method does not consider the problems of the installation and measurement accuracy of the material in the instrument after the soil body structure is completely destroyed after more dry-wet cycles, meanwhile, the influence of temperature, stress conditions and penetrating fluid on the permeability of the material when the temperature, the stress conditions and the penetrating fluid are heavy metal liquid, organic polluted liquid, strong acid and strong alkali in the actual environment is not considered, the measurement process needs manual operation, and the process is complicated.
In summary, the prior art mainly has the following disadvantages:
1. the existing method adopts a rigid wall permeation method to measure the permeability coefficient of a material after dry-wet circulation, but does not consider the phenomenon of side leakage caused by dry-wet deformation of a sample, the combined action of the dry-wet circulation, temperature and stress of the sample under the action of an external environment, and the measurement error of the permeability coefficient caused by corrosion of a penetrating fluid on an instrument when the penetrating fluid is a heavy metal liquid, an organic polluted liquid, a strong acid and a strong base;
2. in the existing method, a fixed rigid wall penetration method is adopted to measure the permeability coefficient of a material after dry-wet circulation under the action of stress, but the phenomenon of side leakage caused by dry-wet deformation of a sample is not considered, the combined action of the dry-wet circulation, temperature and stress of the sample under the action of an external environment is considered, and when the penetration liquid is heavy metal liquid, organic polluted liquid, strong acid and strong base, the penetration liquid causes the measurement error of the permeability coefficient due to corrosion on an instrument;
3. the existing method adopts a flexible wall permeation method to measure the permeability coefficient of a material after dry-wet circulation, but does not consider the combined action of the dry-wet circulation, the temperature and the stress of a sample under the action of an external environment, and when the permeation liquid is heavy metal liquid, organic polluted liquid, strong acid and strong base, the permeation liquid causes the measurement error of the permeability coefficient due to corrosion of an instrument, and the control method does not realize automatic monitoring and has a complex realization process.
Disclosure of Invention
The present invention is intended to solve the above problems, and more specifically, to improve the reliability of the test and to enable the test under the condition of a plurality of dry and wet cycles.
The purpose of the invention can be realized by the following technical scheme, and the invention provides a flexible wall penetration test method for temperature-stress integrated control under dry and wet circulation, which comprises the following steps:
step 1, arranging a flexible wall permeameter, wherein the flexible wall permeameter comprises a test device, a pressurizing device, a permeation system and a confining pressure system; the osmotic system comprises a pressure stabilizer and an injection chamber a, and the confining pressure system comprises an injection chamber b and an injection chamber c; the three injection chambers are the same in shape and are composed of an upper half chamber, a lower half chamber and a flexible rubber membrane, each injection chamber is divided into two spaces which are sealed up and down by the flexible rubber membrane, the side wall of the lower half chamber close to the flexible rubber membrane is provided with an injection hole, and the upper half chamber is provided with an exhaust hole; the three injection chambers are communicated with the pressure stabilizer through air pipes respectively, and an air regulating valve and a numerical pressure gauge are connected in series between each injection chamber and the pressure stabilizer;
the testing device is formed by assembling a top cover, a main body and a base; the main body comprises a hollow cylinder and a rubber film, the rubber film is rolled into a cylinder shape and then sleeved in the hollow cylinder, a gap between the outer surface of the rubber film and the inner wall of the hollow cylinder forms a closed confining pressure chamber between the top cover and the base, an upper through channel and a lower through channel are formed in the confining pressure chamber, a top exhaust channel, a penetrating fluid output channel and a drainage channel are formed in the top cover, and a drainage channel, a bottom exhaust channel and a penetrating fluid input channel are formed in the base; a hemispherical pit is formed in the center of the top cover, and a small steel ball corresponding to the hemispherical pit is arranged in the top of the top cover;
the pressurizing device comprises a top pressurizing device, a bottom pressurizing device and a pressurizing and measuring device; the top pressurizing device comprises a back pressure ejector rod and a back pressure bolt, the back pressure bolt penetrates through a through hole in the center of the back pressure ejector plate from top to bottom and is contacted with the top of the steel ball, the bottom pressurizing device comprises a pressure chamber and a pressurizing ring, the pressurizing ring is arranged in the pressure chamber, a closed air pressure chamber is formed between the bottom surface of the pressurizing ring and the inner wall of the pressure chamber, the pressurizing measuring device comprises a stabilizing rod and an L-shaped measuring rod, the lower part of the L-shaped measuring rod is connected with the pressurizing ring, and the upper part of the L-shaped measuring rod is connected with one end of the stabilizing rod;
the infiltration system consists of a gas cylinder, a gas pressure relief valve, a gas pressure stabilizer, an injection chamber a and an automatic exudate monitoring and collecting device; the gas cylinder is communicated with the gas pressure stabilizing machine through a gas pressure relief valve; a three-way ball valve a and a back pressure switch are also arranged between the gas pressure stabilizer and the injection chamber a, a back pressure pipe is connected to the three-way ball valve a, and the other end of the back pressure pipe is communicated with the lower half chamber of the injection chamber a; the lower half chamber of the injection chamber a is communicated with a penetrating fluid input channel through a three-way ball valve c; the gas pressure stabilizer is communicated with the gas pressure chamber through a fourth air regulating valve and a shaft pressure gas three-way valve; the automatic monitoring and collecting device for the percolate comprises a percolate collecting device, a conical flask, a data recorder, two anti-corrosion flowmeters and a three-way ball valve d;
the confining pressure system comprises an injection chamber b and an injection chamber c, and a temperature-controllable heating belt is arranged outside the injection chamber c; the lower half chamber of the injection chamber b is communicated with the lower through channel through a three-way ball valve b and a liquid inflow three-way valve, and the other end of the three-way ball valve b is communicated with the lower half chamber of the injection chamber c through a liquid one-way valve; the lower half chamber of the injection chamber c is communicated with the upper through channel through another liquid one-way valve and a liquid outflow three-way valve;
step 2, Overall set of tests
Setting J times of dry-humidity circulation, and recording any one of the J times of dry-humidity circulation as a set time X of dry-humidity circulationjJ1, 2.. J; setting I test temperatures, and recording any one of the test temperatures as a set test temperature TiI is 1, 2 … I; setting A groups of consolidation pressure, and recording any one group as the set consolidation pressure PaThe set consolidation pressure PaIncluding setting a consolidation axial pressure P1aAnd setting a consolidation confining pressure P2aAnd a is 1, 2 … a, i.e., the permeation test method of the present invention comprises J × I × a combinations;
then, carrying out a penetration test on each combination of the J multiplied by I multiplied by A, and synchronously monitoring and recording the states of temperature and stress changes of the sample after the dry-wet cycle times are reached;
specifically, the test steps of any combination are shown in step 3-step 11;
step 3, setting test parameters and recording test data
Given set humidity cycle temperature TxSetting the dry water content w1Setting the saturated water content w2And w is2≥w1；
Given set liquid confining pressure PmWhere M is 1, 2 … M, and the injection pressure is set to PnN is 1, 2 … N, and in the permeation test, a liquid confining pressure P is set for eachmEach set injection pressure PnCarrying out one penetration test;
in the process of the penetration test, four sensors are arranged in the flexible wall permeameter, namely a displacement sensor, a pH sensor, a conductivity sensor and a mass sensor, wherein the displacement sensor is arranged on the stabilizing rod, the pH sensor and the conductivity sensor are arranged in the penetrating fluid collecting device, and the mass sensor is arranged at the bottom of the air pressure chamber;
in the process of the penetration test, a temperature regulator is arranged and used for monitoring the temperature of the temperature-controllable heating belt;
in the process of carrying out the penetration test, the data recorder is respectively connected with the two anti-corrosion flowmeters, the four sensors and the temperature regulator to obtain real-time data, and the real-time data is automatically recorded every 1 minute;
step 4, setting the initial state of the testing device
Firstly, all valves are adjusted to be in a closed state, all channels are closed, the exhaust hole and the liquid injection hole are closed, and the flexible rubber membranes in the three injection chambers are all in an initial state and are in contact with the top of the upper half chamber;
the mass of the sample is weighed and recorded as the initial mass m0Calculating the water content of the sample and recording as the initial water content w0；
Then opening injection holes, injecting deionized water into the three injection chambers, closing the injection holes after the three injection chambers are filled with the deionized water, and rotating the three-way ball valve b to enable the injection chambers b to be communicated with the confining pressure chamber through the inflow liquid three-way valve and the lower through channel;
step 5, installing the sample
Taking down a top cover in the test device, sequentially installing permeable stones, filter paper, a sample, the filter paper and the permeable stones in a cylindrical rubber film from bottom to top, and then locking the top cover with a main body and a base to form a penetration chamber with a closed interior;
placing the test device on a pressurizing ring, and aligning the steel small ball to the center of the bottom end of the back-pressure screw;
step 6, injecting water into the confining pressure chamber
Adjusting an inflow liquid three-way valve to enable the lower through channel to be communicated with a water injection pump, adjusting an outflow liquid three-way valve to enable the upper through channel to be connected with a water bucket, starting the water injection pump to inject deionized water into the confining pressure chamber, and adjusting the outflow liquid three-way valve to enable the confining pressure chamber to be communicated with an injection chamber c through a liquid conveying pipe when the water level reaches the top of the confining pressure chamber and water flows into the water bucket;
step 7, carrying out dry-humidity circulation
Step 7.1, opening the gas cylinder, adjusting a gas pressure relief valve to enable compressed gas to flow into a gas pressure stabilizer, starting heating by a temperature-controllable heating belt, and monitoring the temperature by a temperature regulator;
step 7.2, adjusting an air adjusting valve at the upper end of the injection chamber c to apply micro pressure to the injection chamber c, rotating the three-way ball valve b to enable the lower half chamber of the injection chamber c to be communicated with the inflow liquid three-way valve, enabling deionized water in the injection chamber c to enter the confining pressure chamber and flow back to the injection chamber c through the outflow liquid three-way valve, and realizing continuous circulation;
step 7.3, when the temperature of the temperature-controllable heating belt reaches the set dry-humidity circulating temperature TxAt this time, the mass of the sample at that time was recorded and recorded as the overall mass m1；
Opening all the drainage channels to enable the sample to enter an evaporation state;
step 7.4, when the water content of the sample reaches the set dry water content w1At the same time, the heating is stopped, and the air regulating valve regulating the upper end of the injection chamber a applies a constant saturated pressure P to the injection chamber atThe deionized water enters the infiltration chamber through the infiltration liquid input channel to moisten the sample, and the air regulating valve at the upper end of the injection chamber b is regulated to apply the same saturation pressure P to the injection chamber bt；
Step 7.5, when the water content of the sample reaches the set saturated water content w2When the method is used, one-time dry-humidity circulation is completed;
step 7.6, checking whether the set dry-humidity cycle times X are reachedjIf yes, entering step 8, otherwise, returning to step 7.1, and continuing to perform the humidity cycle;
step 8, applying axial pressure
Step 8.1, zeroing the air regulating valve of the injection chamber a, respectively communicating the two anti-corrosion flow meters with the permeate inlet channel and the permeate outlet channel, recording the mass of the sample at the moment and recording as the balance mass m2；
The gas pressure stabilizer applies a constant axial pressure P to the pressure chamber through the axial pressure gas three-way valveh，Ph＝4m2g/(πR2) Wherein R is the inner radius of the pressure chamber, and g is 9.8N/kg;
adjusting the back-pressure screw to enable the lower bottom surface of the back-pressure screw to be in contact with the steel ball, and fixing the back-pressure screw by using an adjusting nut; adjusting the position of the stabilizing rod on the L-shaped measuring rod to enable a probe of the displacement sensor to be in contact with the upper surface of the back-pressure screw;
8.2, adjusting the axial pressure gas three-way valve to enable the gas pressure chamber to be communicated with the pressure stabilizer; the fourth air regulating valve is firstly adjusted to zero and then adjusted again, and a set consolidation axial pressure P1 is applied to the air pressure chambera(ii) a An air regulating valve for regulating the injection chamber b, and a set consolidation confining pressure P2 applied to the confining pressure chamber through the injection chamber ba，P2a＞P1a(ii) a Recording the vertical deformation of the sample through a data recorder, and finishing the consolidation process when the vertical deformation is less than 0.01mm within 1 hour;
step 9, removing air bubbles
Step 9.1, adjusting the temperature of the temperature-controllable heating belt to be the set test temperature T through the temperature regulatoriAdjusting an air adjusting valve at the upper end of the injection chamber c, and applying a set consolidation confining pressure P to the confining pressure chamber through the injection chamber ca2；
Step 9.2, after the temperature is stabilized, adjusting an air adjusting valve at the upper end of the injection chamber a, and applying an initial injection pressure P to the infiltration chamber through the injection chamber ad，Pd＜P2a；
9.3, opening a top exhaust channel and a bottom exhaust channel of the test device, and removing visible bubbles in the sample and the rubber film;
after removing the bubbles, closing the top exhaust channel and the bottom exhaust channel;
step 10, injecting a permeate and developing a permeation test
Step 10.1, closing the penetrating fluid inflow channel, opening the liquid injection hole, adjusting an air adjusting valve of the injection chamber a, applying pressure to the upper part of the flexible rubber membrane, discharging deionized water from the liquid injection hole, after the lower half chamber is emptied, contacting the emulsion membrane with the bottom of the lower half chamber of the injection chamber a, and closing the liquid injection hole;
step 10.2, opening the vent hole, opening a side wall back pressure switch, closing the back pressure switch, rotating the three-way ball valve a to enable gas to enter the lower half chamber, applying pressure to the lower part of the flexible rubber film, rebounding the flexible rubber film to be in contact with the top of the upper half chamber, and closing the vent hole;
step 10.3, closing a side wall back pressure switch, zeroing the three-way ball valve a, opening a liquid injection hole, injecting seepage liquid into the injection chamber a, closing the liquid injection hole after the liquid injection hole is filled, opening the back pressure switch, and rotating the three-way ball valve a to enable the gas pressure stabilizer to be communicated with the upper half chamber of the injection chamber a;
step 10.4, zeroing the air regulating valve of the injection chamber c, and then readjusting to stabilize the confining pressure in the confining pressure chamber to the set liquid confining pressure Pm(ii) a Adjusting an air adjusting valve of the injection chamber to stabilize the injection pressure to a set injection pressure PnThe penetrating fluid flows into the penetrating chamber from the injection chamber a through an anti-corrosion input flow meter and a penetrating chamber input channel, and then flows into a penetrating fluid collecting device through a penetrating fluid output channel and another anti-corrosion output flow meter;
in the test process, when the penetrating fluid of the injection chamber a is exhausted, closing the penetrating fluid input channel, returning to the step 10.2, re-injecting the penetrating fluid, and continuing the test;
step 10.5, when the condition of stopping the penetration test is met, stopping the penetration liquid injection, automatically storing the current real-time penetration liquid output flow Q, and entering the step 11; otherwise, returning to the step 10.4 and continuing the test;
step 11, checking N set injection pressures PnIf so, returning to step 10.1 to perform the next set injection pressure Pn(ii) a permeation test; otherwise, go to step 12;
step 11, checking M set liquid confining pressures PmIf yes, returning to step 10.1 to perform next set liquid confining pressure Pm(ii) a permeation test; otherwise, go to step 12;
step 12, calculating the permeability coefficient K
Removing the sample, measuring and recording the final diameter D and the final height L of the sample;
test data in a data recorder are called, and the permeability coefficient K is calculated according to the following formula:
Figure BDA0003247212490000101
wherein, deltah is the water head difference,
Figure BDA0003247212490000111
Hwheight of water column at standard atmospheric pressure, PstandardIs 1 atm.
2. The method for the temperature-stress integrated control flexible wall permeation test under dry and wet cycles according to claim 1, wherein the permeation test termination condition is determined as follows:
setting the interval to be 1 hour, carrying out data comparison once, and recording real-time data obtained during data comparison as comparison instant data;
when the penetrating fluid is water, the conditions for terminating the penetration test are that the following conditions are simultaneously met:
(1) the ratio of the instantaneous penetrant input flow and the instantaneous penetrant output flow measured during the continuous 4 times of data comparison is 0.75-1.25;
(2) finally, the comparison instantaneous penetrant output flow measured in 4 times of continuous data comparison is between 0.75 and 1.25 times of the average flow value, and the average flow value is the average of 60 real-time penetrant output flows recorded in two data comparison intervals;
when the penetrating fluid is a heavy metal solution or an organic polluted solution, the condition for terminating the penetration test also needs to satisfy the following conditions in addition to the above regulation:
(3) comparing the difference between the instantaneous permeate output flow and the instantaneous permeate input flow to be greater than or equal to 2 times of the sample pore volume;
(4) the conductivity compared to the instantaneous permeate output is within ± 10% of the initial conductivity;
(5) the pH value of the compared instantaneous penetrating fluid output is within +/-10% of the initial pH value.
Compared with the prior art, the invention has the beneficial effects that:
1. the test method can measure the permeability coefficients of various penetrating fluids such as heavy metal, organic matters and other polluted liquids on a sample acted on temperature-stress simultaneously under dry-wet circulation;
2. the method is simple, and the change rules of the permeability coefficient and other indexes can be automatically monitored in real time only by controlling the data recorder.
3. The permeameter of the present invention can perform infiltration and collection of a variety of permeate fluids, such as: heavy metal, organic matter and other polluted liquids cannot cause pollution and corrosion to the instrument in the whole infiltration process, and the service life of the permeameter is effectively prolonged;
4. the flexible wall permeameter and the back pressure device are combined to realize the application and control of the axial force and monitor the deformation of the sample;
5. the injection of confining pressure liquid is greatly reduced while confining pressure is applied, the constant temperature is kept more finely, and the humidity change of the sample is realized by controlling the temperature and circularly injecting water;
6. in the test process, the flow of the infiltration liquid and the flow of the infiltration liquid in the infiltration test process are monitored in real time through the data recorder, and the chemical state of the infiltration liquid can be monitored in real time.
Drawings
FIG. 1 is a flow chart of a test method in an embodiment of the present invention;
FIG. 2 is a schematic diagram of the general structure of a flexible wall permeameter in an embodiment of the invention;
FIG. 3 is a schematic structural diagram of a testing apparatus according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of a pressure enclosing chamber according to an embodiment of the present invention;
FIG. 5 is a schematic structural diagram of a pressurizing device according to an embodiment of the present invention;
FIG. 6 is a schematic view of an exemplary embodiment of an injection chamber a;
FIG. 7 is a schematic view of an exemplary embodiment of an injection chamber b;
FIG. 8 is a schematic view of an exemplary injection chamber c;
fig. 9 is a schematic structural view of an automatic exudate monitoring and collecting device in an embodiment of the present invention.
Reference numerals: 1-a gas bottle, 2-a gas pressure relief valve, 3-a gas pressure stabilizer, 4-an air regulating valve, 5-a fourth air regulating valve, 6-filter paper, 8-a numerical pressure gauge, 9-a temperature-controllable heating belt, 10-an upper through channel, 11-a lower through channel, 12-a three-way ball valve a, 13-a back pressure switch, 14-an exhaust hole, 15-a flexible rubber membrane, 16-a liquid injection hole, 17-a side wall back pressure switch, 18-a liquid one-way valve, 19-a three-way ball valve b, 20-a switch and 21-a sample; 22-steel pellets, 23-sliding columns, 24-back pressure pipes, 25-top covers, 26-top exhaust channels, 27-drainage channels, 28-penetrating fluid output channels, 29-permeable stones, 30-sealing rings, 31-outflow liquid three-way valves, 32-inflow liquid three-way valves, 33-permeation chambers, 34-main bodies, 35-confining pressure chambers, 36-rubber membranes, 38-bottom exhaust channels, 39-penetrating fluid input channels, 40-temperature regulators, 41-bases, 43-fixing rods, 44-adjusting nuts, 45-back pressure screws, 46-back pressure rods, 47-displacement sensors, 48-stabilizer bars, 49-L-shaped measuring rods, 50-pressurizing rings, 51-pressure chambers, 52-axial pressure gas three-way valves, 53-counter pressure base, 54-mass sensor, 55-air pressure chamber, 56-anti-corrosion flow meter, 57-conductivity sensor, 58-pH sensor, 59-penetrating fluid collecting device, 60-conical flask, 61-data recorder, 63-three-way ball valve d, 64-three-way ball valve c.
Detailed Description
The present invention will be described in detail below with reference to the accompanying drawings and examples.
The invention relates to a flexible wall penetration test method with temperature-stress integrated control under dry-wet circulation, which comprises the following steps:
step 1, a flexible wall permeameter is arranged, and the flexible wall permeameter comprises a test device, a pressurizing device, a permeation system and a confining pressure system.
The osmotic system comprises a pressure stabilizer 3 and an injection chamber a, and the confining pressure system comprises an injection chamber b and an injection chamber c; the three injection chambers are the same in shape and are composed of an upper half chamber, a lower half chamber and a flexible rubber film 15, each injection chamber is divided into two spaces which are sealed up and down by the flexible rubber film 15, the side wall of the lower half chamber close to the flexible rubber film 15 is provided with an injection hole 16, and the upper half chamber is provided with an exhaust hole 14; the three injection chambers are respectively communicated with the pressure stabilizer 3 through air pipes, and an air regulating valve 4 and a numerical pressure gauge 8 are connected in series between each injection chamber and the pressure stabilizer 3.
The testing device is assembled by a top cover 25, a main body 34 and a base 41; the main body 34 comprises a hollow cylinder and a rubber membrane 36, the rubber membrane 36 is rolled into a cylinder shape and then sleeved in the hollow cylinder, a gap between the outer surface of the rubber membrane 36 and the inner wall of the hollow cylinder forms a closed confining pressure chamber 35 between the top cover 25 and the base 41, the confining pressure chamber 35 is provided with an upper through channel 10 and a lower through channel 11, the top cover 25 is provided with a top exhaust channel 26, a penetrating fluid output channel 28 and a drainage channel 27, and the base 41 is provided with a drainage channel 27, a bottom exhaust channel 38 and a penetrating fluid input channel 39; a hemispherical pit is arranged at the center of the top cover 25 and is provided with a steel ball 22 corresponding to the hemispherical pit.
The pressurizing device comprises a top pressurizing device, a bottom pressurizing device and a pressurizing and measuring device; the top pressurizing device comprises a back pressure mandril 46 and a back pressure bolt 45, the back pressure bolt 45 penetrates through a through hole in the center of the back pressure mandril 46 from top to bottom and is contacted with the top of the steel ball 22, the bottom pressurizing device comprises a pressure chamber 51 and a pressurizing ring 50, the pressurizing ring 50 is arranged in the pressure chamber 51, a closed air pressure chamber 55 is formed between the bottom surface of the pressurizing ring 50 and the inner wall of the pressure chamber 51, the pressurizing measuring device comprises a stabilizing rod 48 and an L-shaped measuring rod 49, the lower part of the L-shaped measuring rod 49 is connected with the pressurizing ring 50, and the upper part of the L-shaped measuring rod 49 is connected with one end of the stabilizing rod 48.
The infiltration system consists of a gas cylinder 1, a gas pressure relief valve 2, a gas pressure stabilizer 3, an injection chamber a and an automatic exudate monitoring and collecting device; the gas bottle 1 is communicated with a gas pressure stabilizer 3 through a gas pressure relief valve 2; a three-way ball valve a12 and a back pressure switch 13 are also arranged between the gas pressure stabilizer 3 and the injection chamber a, a back pressure pipe 24 is connected on the three-way ball valve a12, and the other end of the back pressure pipe 24 is communicated with the lower half chamber of the injection chamber a; the lower half chamber of the injection chamber a is communicated with the penetrating fluid input channel 39 through a three-way ball valve c 64; the gas pressure stabilizer 3 is communicated with the gas pressure chamber 55 through a fourth air regulating valve 5 and the axial pressure gas three-way valve 52; the automatic monitoring and collecting device for the percolate comprises a percolate collecting device 59, a conical bottle 60, a data recorder 61, two anti-corrosion flow meters 56 and a three-way ball valve d 63.
The confining pressure system comprises an injection chamber b and an injection chamber c, and a temperature-controllable heating belt 9 is arranged outside the injection chamber c. The lower half chamber of the injection chamber b is communicated with the lower through channel 11 through a three-way ball valve b19 and an inflow liquid three-way valve 32, and the other end of the three-way ball valve b19 is communicated with the lower half chamber of the injection chamber c through a liquid one-way valve 18; the lower half of the filling chamber c communicates with the upper through-passage 10 through another liquid check valve 18, an outflow liquid three-way valve 31.
Step 2, Overall set of tests
Setting J times of dry-humidity circulation, and recording any one of the J times of dry-humidity circulation as a set time X of dry-humidity circulationjJ1, 2.. J; setting I test temperatures, and recording any one of the test temperatures as a set test temperature TiI is 1, 2 … I; setting A groups of consolidation pressure, and recording any one group as the set consolidation pressure PaThe set consolidation pressure PaIncluding setting a consolidation axial pressure P1aAnd setting a consolidation confining pressure P2aAnd a is 1, 2 … a, i.e., the permeation test method of the present invention comprises J × I × a combinations;
then, permeation test is carried out for each combination of J × I × A, and the state of temperature and stress changes of the sample after reaching the dry and wet cycle number is synchronously monitored and recorded.
Specifically, the experimental procedures for any one combination are shown in step 3-step 11.
Step 3, setting test parameters and recording test data
Given set humidity cycle temperature TxSetting the dry water content w1Setting the saturated water content w2And w is2≥w1；
The set liquid confining pressure Pm, M is 1, 2 … M, and the set injection pressure is givenForce PnN is 1, 2 … N, and in the permeation test, a liquid confining pressure P is set for eachmEach set injection pressure PnCarrying out one penetration test;
during the permeation test, four sensors, namely a displacement sensor 47, a pH sensor 58, a conductivity sensor 57 and a mass sensor 54 are installed in the flexible wall permeameter, wherein the displacement sensor 47 is installed on the stabilizing rod 48, the pH sensor 58 and the conductivity sensor 57 are placed in the permeate collecting device 59, and the mass sensor 54 is placed at the bottom of the air pressure chamber 55;
in the process of the penetration test, a temperature regulator 40 is arranged for monitoring the temperature of the temperature-controllable heating belt 9;
in the process of the penetration test, the data recorder 61 is respectively connected with the two anti-corrosion flowmeters 56, the four sensors and the temperature regulator 40 to obtain real-time data, and the real-time data is automatically recorded every 1 minute.
Step 4, setting the initial state of the testing device
Firstly, all valves are adjusted to be in a closed state, all channels are closed, the exhaust hole 14 and the liquid injection hole 16 are closed, and the flexible rubber membranes 15 in the three injection chambers are in contact with the top of the upper half chamber in the initial state;
the mass of the sample is weighed and recorded as the initial mass m0Calculating the water content of the sample and recording as the initial water content w0；
Then, the injection hole 16 is opened, deionized water is injected into the three injection chambers, the injection hole 16 is closed after the filling, and the three-way ball valve b19 is rotated to connect the injection chamber b to the confining pressure chamber 35 through the inflow liquid three-way valve 32 and the lower through passage 11.
Step 5, mounting the sample 21
Taking down the top cover 25 in the test device, sequentially installing the permeable stone 29, the filter paper 6, the sample 21, the filter paper 6 and the permeable stone 29 in the rubber film 36 rolled into a cylinder from bottom to top, and then locking the top cover 25 with the main body 34 and the base 41 to form a permeation chamber 33 with an inner closed part;
the test device is placed on the pressure ring 50 with the steel ball 22 aligned with the center of the bottom end of the counter-pressure screw 45.
Step 6, injecting water into the confining pressure chamber 35
The inflow liquid three-way valve 32 is adjusted to communicate the lower through passage 11 with a water injection pump, the outflow liquid three-way valve 31 is adjusted to communicate the upper through passage 10 with a water tank, the water injection pump is started to inject deionized water into the confining pressure chamber 35, and when the water level reaches the top of the confining pressure chamber 35 and water flows into the water tank, the outflow liquid three-way valve 31 is adjusted to communicate the confining pressure chamber 35 with the injection chamber c through a liquid transfer tube.
Step 7, carrying out dry-humidity circulation
Step 7.1, opening the gas cylinder 1, adjusting the gas pressure relief valve 2 to enable compressed gas to flow into the gas pressure stabilizing machine 3, starting heating by the temperature-controllable heating belt 9, and monitoring the temperature by the temperature regulator 40;
step 7.2, the air regulating valve 4 at the upper end of the injection chamber c is regulated to apply micro pressure to the injection chamber c, the three-way ball valve b19 is rotated to enable the lower half chamber of the injection chamber c to be communicated with the inflow liquid three-way valve 32, deionized water in the injection chamber c enters the confining pressure chamber 35 and flows back to the injection chamber c through the outflow liquid three-way valve 31, and continuous circulation is achieved;
step 7.3, when the temperature of the temperature-controllable heating belt 9 reaches the set dry-humidity circulating temperature TxAt this time, the mass of the sample 21 was recorded and recorded as the total mass m1；
Opening all the drainage channels 27 to bring the sample 21 into an evaporation state;
step 7.4, when the water content of the sample reaches the set dry water content w1At this time, the heating is stopped, and the air regulating valve 4 for regulating the upper end of the injection chamber a applies a constant saturation pressure P to the injection chamber atThe sample 21 is humidified by introducing deionized water into the permeation chamber 33 through the permeate introduction passage 39, and the air adjustment valve 4 at the upper end of the injection chamber b is adjusted to apply the same saturation pressure P to the injection chamber bt；
Step 7.5, when the water content of the sample reaches the saturated water content w2When the method is used, one-time dry-humidity circulation is completed;
step 7.6, checking whether the set dry-humidity cycle times X are reachedjTo achieve, enter the stepAnd 8, otherwise, returning to the step 7.1, and continuing to perform the dry-humidity cycle.
Step 8, applying axial pressure
Step 8.1, zeroing the air control valve 4 of the injection chamber a and connecting the two corrosion protection flowmeters 56 to the permeate inlet and outlet channels 39, 28, respectively, recording the mass of the sample 21 at that time and recording it as the equilibrium mass m2；
The gas pressure stabilizer 3 applies a constant axial pressure P to the pressure chamber 51 through the axial pressure gas three-way valve 52h，Ph＝4m2g/(πR2) Wherein R is the inner radius of the pressure chamber 51, g ═ 9.8N/kg;
adjusting the back pressure screw 45 to make the lower bottom surface of the back pressure screw 45 contact with the steel ball 22 and fixing by an adjusting nut 44; the position of the stabilizer bar 48 on the L-shaped measuring rod 49 is adjusted, so that the probe of the displacement sensor 47 is in contact with the upper surface of the back-pressure screw 45;
step 8.2, adjusting the axial pressure gas three-way valve 52 to enable the gas pressure chamber 55 to be communicated with the pressure stabilizer 3; the fourth air adjustment valve 5 is first zeroed and then readjusted and a set consolidation axial pressure P1 is applied to the air pressure chamber 55a(ii) a An air regulating valve 4 for regulating the injection chamber b, and a set consolidation ambient pressure P2 applied to the ambient pressure chamber 35 via the injection chamber ba，P2a＞P1a(ii) a The vertical deformation of the sample is recorded by the data recorder 61 and the consolidation process is ended when the vertical deformation is less than 0.01mm within 1 hour.
Step 9, removing air bubbles
Step 9.1, adjusting the temperature of the temperature-controllable heating belt 9 to the set test temperature T by the temperature regulator 40iAn air regulating valve 4 for regulating the upper end of the injection chamber c and a set consolidation confining pressure P applied to the confining pressure chamber 35 via the injection chamber ca2；
Step 9.2, after the temperature is stabilized, the air adjustment valve 4 at the upper end of the infusion chamber a is adjusted to apply an initial infusion pressure P to the infiltration chamber 33 through the infusion chamber ad，Pd＜P2a；
Step 9.3, opening a top exhaust channel 26 and a bottom exhaust channel 38 of the test device, and removing visible bubbles in the test sample 21 and the rubber film 36;
after the air bubbles are removed, the top vent passage 26 and the bottom vent passage 38 are closed.
Step 10, injecting a permeate and developing a permeation test
Step 10.1, closing the penetrating fluid inflow channel 39, opening the injection hole 16, adjusting the air adjusting valve 4 of the injection chamber a, applying pressure on the upper part of the flexible rubber membrane 15, discharging deionized water from the injection hole 16, after the lower half chamber is emptied, contacting the emulsion membrane with the bottom of the lower half chamber of the injection chamber a, and closing the injection hole 16;
step 10.2, opening the vent hole 14, opening the side wall back pressure switch 17, closing the back pressure switch 13, rotating the three-way ball valve a12 to enable gas to enter the lower half chamber, applying pressure to the lower part of the flexible rubber film 15, rebounding the flexible rubber film 15 to be in contact with the top of the upper half chamber, and closing the vent hole 14;
step 10.3, closing the side wall back pressure switch 17, zeroing the three-way ball valve a12, opening the liquid injection hole 16, injecting seepage liquid into the injection chamber a, closing the liquid injection hole 16 after full injection, opening the back pressure switch 13, and rotating the three-way ball valve a12 to enable the gas pressure stabilizer 3 to be communicated with the upper half chamber of the injection chamber a;
step 10.4, zeroing the air adjustment valve 4 of the injection chamber c and then readjusting to stabilize the confining pressure in the confining pressure chamber 35 to the set liquid confining pressure Pm(ii) a An air regulating valve 4 for regulating the injection chamber a to stabilize the injection pressure to a set injection pressure PnThe penetrating fluid flows from the injection chamber a into the penetrating chamber 33 through an anti-corrosion input flow meter 62 and a penetrating chamber input channel 39, and then flows into a penetrating fluid collecting device 59 through a penetrating fluid output channel 28 and another anti-corrosion output flow meter 56;
during the test, when the penetrating fluid of the injection chamber a is exhausted, the penetrating fluid input channel 39 is closed, the step 10.2 is returned, the penetrating fluid is injected again, and the test is continued;
step 10.5, when the condition of stopping the penetration test is met, stopping the penetration liquid injection, automatically storing the current real-time penetration liquid output flow Q, and entering the step 11; otherwise, returning to the step 10.4 and continuing the test.
The permeation test termination conditions were determined as follows:
setting the interval to be 1 hour, carrying out data comparison once, and recording real-time data obtained during data comparison as comparison instant data;
when the penetrating fluid is water, the conditions for terminating the penetration test are that the following conditions are simultaneously met:
(1) the ratio of the instantaneous penetrant input flow and the instantaneous penetrant output flow measured during the continuous 4 times of data comparison is 0.75-1.25;
(2) and finally, comparing the instantaneous penetrant output flow measured in 4 times of data comparison, wherein the instantaneous penetrant output flow is 0.75-1.25 times of the average flow value, and the average flow value is the average of 60 real-time penetrant output flows recorded in the two data comparison intervals.
When the penetrating fluid is a heavy metal solution or an organic polluted solution, the condition for terminating the penetration test also needs to satisfy the following conditions in addition to the above regulation:
(3) comparing the difference between the instantaneous permeate output flow and the instantaneous permeate input flow to be greater than or equal to 2 times of the sample pore volume;
(4) the conductivity compared to the instantaneous permeate output is within ± 10% of the initial conductivity;
(5) the pH value of the compared instantaneous penetrating fluid output is within +/-10% of the initial pH value.
Step 11, checking N set injection pressures PnIf so, returning to step 10.1 to perform the next set injection pressure Pn(ii) a permeation test; otherwise, step 12 is entered.
Step 11, checking M set liquid confining pressures PmIf yes, returning to step 10.1 to perform next set liquid confining pressure Pm(ii) a permeation test; otherwise, step 12 is entered.
Step 12, calculating the permeability coefficient K
Removing the sample, measuring and recording the final diameter D and the final height L of the sample;
test data in a data recorder are called, and the permeability coefficient K is calculated according to the following formula:
Figure BDA0003247212490000221
wherein, deltah is the water head difference,
Figure BDA0003247212490000222
Hwheight of water column at standard atmospheric pressure, PstandardIs 1 atm.
Fig. 1 shows step 4 to step 11 among the above steps.
In this embodiment, the number of dry and wet cycles X is setjThe method comprises the following steps: 0, 1, 3, 5 times; set the humidity cycle temperature TxAt 60 ℃ and setting the test temperature TiSet at 30, 40, 50 ℃ and set at a consolidation axial pressure P1aThe method comprises the following steps: 70, 80 and 90kPa, and the corresponding set consolidation confining pressure P2aComprises the following steps: 70, 80 and 90kPa, and the liquid confining pressure P is setmThe method comprises the following steps: 70, 90, 110kPa, setting the injection pressure PnThe method comprises the following steps: 50, 70 and 90 kPa.
In this embodiment, the set dry water content w1And setting the saturated water content w2All values of (2 w)jWherein w isjIs the boundary water content of the cohesive soil from 0 to the plastic state and the flowing state, and w2＞w1。
It can be seen from the above test processes that in the test process of the present invention, a series of permeation tests of different dry and wet cycle times, different test temperatures, different consolidation pressures, different injection air pressures, different injection confining pressures, etc. can be performed on different samples to obtain a large amount of data about soil pressure-deformation-permeation, and the data is transmitted to an external computer system through the data recorder 61 to be collated, so that the permeation mechanism of the liquid in the soil after dry and wet cycles can be comprehensively understood.
In this embodiment, the specific structure of the flexible wall permeameter described in step 1 is shown in fig. 2 to 9. Fig. 2 is a schematic structural diagram of a flexible wall permeameter in an embodiment of the present invention, fig. 3 is a schematic structural diagram of a testing apparatus in an embodiment of the present invention, fig. 4 is a schematic structural diagram of a confining chamber in an embodiment of the present invention, fig. 5 is a schematic structural diagram of a pressurizing apparatus in an embodiment of the present invention, fig. 6 is a schematic structural diagram of an injection chamber a in an embodiment of the present invention, fig. 7 is a schematic structural diagram of an injection chamber b in an embodiment of the present invention, fig. 8 is a schematic structural diagram of an injection chamber c in an embodiment of the present invention, and fig. 9 is a schematic structural diagram of an automatic monitoring and collecting apparatus for exudate in an embodiment of the present invention. As can be seen from the above figures, the flexible wall permeameter according to step 1 of the present invention comprises a testing device, a pressurizing device, a permeation system, a confining pressure system and a sensor group.
The sensor group includes a displacement sensor 47, a pH sensor 58, a conductivity sensor 57, and a mass sensor 54. The osmotic system comprises an injection chamber a, the confining pressure system comprises an injection chamber b and an injection chamber c, the three injection chambers are the same in shape and are composed of an upper half chamber, a lower half chamber and a flexible rubber membrane 15, the flexible rubber membrane 15 is placed between the upper half chamber and the lower half chamber, the edge of the flexible rubber membrane is clamped by the upper half chamber and the lower half chamber in a butt joint mode, the injection chamber is divided into two spaces which are closed up and down, and an injection hole 16 is formed in the side wall, close to the flexible rubber membrane 15, of the lower half chamber.
The test device comprises a top cover 25, a main body 34, a base 42 and two permeable stones 29.
The top cover 25 is composed of a large coaxial hollow cylinder A and a sliding column 23 nested in the large coaxial hollow cylinder A, and the bottom surface of the sliding column 23 is higher than that of the large coaxial hollow cylinder A. The sliding column 23 is provided with 4 through channels from top to bottom, which are respectively a top exhaust channel 26, a penetrating fluid output channel 28 and 2 drainage channels 27. A hemispherical pit is formed in the center of the top of the sliding column 23, a small steel ball 22 corresponding to the hemispherical pit is arranged in the center, and a permeable stone 29 is embedded at the bottom of the sliding column 23.
The base 41 is formed by fixedly connecting a small coaxial cylinder and a large coaxial cylinder from top to bottom, and the top of the small coaxial cylinder is inlaid with a permeable stone 29; from the top to the bottom of the base 41 there are 3 through drainage channels 27, from the top of the small coaxial cylinder to the side wall of the large coaxial cylinder there are 2L-shaped channels, one of which is the bottom exhaust channel 38 and one of which is the permeate inlet channel 39.
The main body 34 is composed of a large coaxial hollow cylinder B and a rubber membrane 36, the part of the large coaxial hollow cylinder B, which is away from two end faces by the height H, is recorded as a section H, the other parts are recorded as sections H, and H is less than or equal to 5 cm. And (3) setting the inner diameter of the H section as r1, the inner diameter of the H section as r2, r2 as large as or equal to r1, rolling the rubber film 36 into a cylindrical shape and fixing the cylindrical rubber film on the inner wall of the H part, and forming a closed cylindrical space between the outer surface of the rubber film 36 and the inner wall of the H section, wherein the space is marked as a confining chamber 35. The upper end and the lower end of the H section are respectively provided with a through channel from the outer wall to the confining pressure chamber 35 and are respectively marked as an upper through channel 10 and a lower through channel 11. The specific structure of the confining chamber can be seen in figure 4, wherein epsilon is a gap formed between the rubber film 36 and the inner wall of the H end, and epsilon is less than or equal to 5 mm.
The outer diameters of the sliding column 23 and the small coaxial cylinder are the same as the inner diameter of the h section of the large coaxial hollow cylinder B, the sliding column 23 is inserted into the large coaxial hollow cylinder B from the upper end of the main body 34 and the small coaxial cylinder from the lower end of the main body 34 respectively and locked by a locking tool, a complete test device is formed, and a closed permeation chamber 33 is formed inside the rubber membrane 36.
In this embodiment, the locking means includes a bolt and a nut, and specifically, through holes are uniformly formed in the top cover 25, the main body 34, and the base 41, and then the bolt is inserted and locked at both ends by the nut.
The pressurizing device comprises a top pressurizing device, a bottom pressurizing device and a pressurizing and measuring device; the top pressurizing device consists of a back pressure mandril 46, a back pressure bolt 45 and an adjusting nut 44, wherein the back pressure bolt 45 penetrates through a through hole in the center of the back pressure top plate 46 from top to bottom to face downwards and is in contact with the top of the steel ball 22, and the adjusting nut 44 is sleeved on the back pressure bolt 45 and is used for adjusting the movement of the back pressure bolt 45. The bottom pressurizing means consists of a counter-pressure base 53, a pressure chamber 51 and a pressurizing ring 50. The pressure chamber 51 is mounted on a counter pressure base 53, and the lower end of the pressure chamber 51 is communicated with an axial pressure gas three-way valve 52. The pressurizing ring 50 is installed in the pressure chamber 51, and the sealing ring 30 is installed on the contact surface of the outer surface and the pressure chamber 51, when the pneumatic gas three-way valve 52 is opened, a closed pneumatic chamber 55 is formed between the bottom surface of the pressurizing ring 50 and the inner wall of the pressure chamber 51. The mass sensor 54 is mounted on the floor of the air pressure chamber 55.
Two inner screw holes are symmetrically formed in the back pressure base 53, two through holes are symmetrically formed in the back pressure mandril 46, and the two fixing rods 43 penetrate through the two through holes of the back pressure mandril 46 to be inserted into the two inner screw holes of the back pressure base 53 and are locked by nuts. The pressurization measuring device comprises a displacement sensor 47, a stabilizer bar 48 and an L-shaped measuring rod 49, wherein one end of the stabilizer bar 49 is connected with the displacement sensor 47, and the other end of the stabilizer bar 49 is provided with a through hole. The lower part of the L-shaped measuring rod 49 is connected with the pressurizing ring 50, the outer wall of the upper part of the L-shaped measuring rod is provided with threads, and the L-shaped measuring rod penetrates through a through hole at one end of the stabilizing rod 48 and is locked by a nut.
The infiltration system consists of a gas cylinder 1, a gas pressure relief valve 2, a gas pressure stabilizing machine 3, an injection chamber a and an automatic exudate monitoring and collecting device; the gas cylinder 1, the gas pressure relief valve 2, the gas pressure stabilizer 3 and the upper half chamber of the injection chamber a are communicated in sequence through gas pipes, an air regulating valve 4, a numerical pressure gauge 8, a three-way ball valve a12 and a back pressure switch 13 are sequentially arranged between the gas pressure stabilizer 3 and the injection chamber a, a back pressure pipe 24 is connected to the three-way ball valve a12, and the other end of the back pressure pipe 24 is communicated with the lower half chamber of the injection chamber a. The lower half chamber of the injection chamber a is communicated with a three-way ball valve c64 and a penetrating fluid input channel 39 in turn through a liquid conveying pipe. The gas pressure stabilizer 3 is communicated with the axial pressure gas three-way valve 52 through a gas pipe, and a fourth air regulating valve 5 and a numerical pressure gauge 8 are arranged between the gas pressure stabilizer and the axial pressure gas three-way valve.
The automatic monitoring and collecting device for the percolate comprises a percolate collecting device 59, a conical flask 60, a data recorder 61, two anti-corrosion flow meters 56 and a three-way ball valve d63, wherein one end of the percolate collecting device 59 is communicated with the conical flask 60, the other end of the percolate collecting device 59 is communicated with a percolate output channel 28 through a three-way ball valve d63, and the third end of the three-way ball valve d63 is connected with a three-way ball valve c 64. The pH sensor 58 and the conductivity sensor 57 are arranged in a penetrating fluid collecting device 59, one anti-corrosion flow meter 56 is arranged between the penetrating fluid collecting device 59 and a three-way ball valve d63, the other anti-corrosion flow meter 56 is arranged between a three-way ball valve c64 and an injection chamber a5, and a data recorder 61 is respectively connected with the four sensors, the two anti-corrosion flow meters 56, the three-way ball valve c64 and the three-way ball valve d63 through leads.
The confining pressure system comprises an injection chamber b and an injection chamber c, and a temperature-controllable heating belt 9 is arranged outside the injection chamber c. The upper half chambers of the injection chamber b and the injection chamber c are communicated with the gas pressure stabilizer 3 through gas pipes, and an air regulating valve 4 and a numerical pressure gauge 8 are arranged between the upper half chambers and the lower half chambers. The lower half chamber of the injection chamber b is communicated with a three-way ball valve b19, an inflow liquid three-way valve 32 and a lower through channel 11 in sequence through a liquid conveying pipe, and the other end of the three-way ball valve b19 is communicated with the lower half chamber of the injection chamber c through a liquid one-way valve 18. The lower half chamber of the injection chamber c is communicated with another liquid one-way valve 18, a liquid outflow three-way valve 31 and an upper through channel 10 through a liquid conveying pipe.
In addition, as can be seen from the above figures, the sliding column 23 and the small coaxial cylinder are provided with sealing rings 30. Two sealing rings are arranged on the sliding column 23, and one sealing ring is arranged on the small coaxial cylinder. The top of the injection chamber a, the top of the injection chamber b and the top of the injection chamber c are provided with vent holes 14, a plug capable of being closed/opened is arranged at the vent hole 14, and a plug capable of being closed/opened is arranged at the injection hole 16. The temperature-controllable heating belt 9 is connected with a temperature regulator 40.
In this embodiment, the drainage channels 27 are provided with plugs. The penetrating fluid output channel 28 and the penetrating fluid input channel 39 are both communicated with the infusion tube, and the infusion tube is provided with a switch 20. The top exhaust passage 26 and the bottom exhaust passage 38 are both in communication with an external air duct, and the air duct is provided with a switch 20.

Claims (2)

1. A flexible wall penetration test method for temperature-stress integrated control under dry and wet cycles is characterized by comprising the following steps:
step 1, arranging a flexible wall permeameter, wherein the flexible wall permeameter comprises a test device, a pressurizing device, a permeation system and a confining pressure system; the osmotic system comprises a pressure stabilizer (3) and an injection chamber a, and the confining pressure system comprises an injection chamber b and an injection chamber c; the three injection chambers are identical in shape and are composed of an upper half chamber, a lower half chamber and a flexible rubber film (15), each injection chamber is divided into two spaces which are sealed up and down by the flexible rubber film (15), the side wall of the lower half chamber close to the flexible rubber film (15) is provided with an injection hole (16), and the upper half chamber is provided with an exhaust hole (14); the three injection chambers are respectively communicated with the pressure stabilizing machine (3) through air pipes, and an air regulating valve (4) and a numerical pressure gauge (8) are connected in series between each injection chamber and the pressure stabilizing machine (3);
the testing device is formed by assembling a top cover (25), a main body (34) and a base (41); the main body (34) comprises a hollow cylinder and a rubber membrane (36), the rubber membrane (36) is rolled into a cylinder shape and then sleeved in the hollow cylinder, a gap between the outer surface of the rubber membrane (36) and the inner wall of the hollow cylinder forms a closed confining pressure chamber (35) between a top cover (25) and a base (41), an upper through channel (10) and a lower through channel (11) are formed in the confining pressure chamber (35), a top exhaust channel (26), a penetrating fluid output channel (28) and a drainage channel (27) are formed in the top cover (25), and a drainage channel (27), a bottom exhaust channel (38) and a penetrating fluid input channel (39) are formed in the base (41); a hemispherical pit is arranged at the center of the top cover (25) and is provided with a small steel ball (22) corresponding to the hemispherical pit;
the pressurizing device comprises a top pressurizing device, a bottom pressurizing device and a pressurizing and measuring device; the top pressurizing device comprises a back pressure ejector rod (46) and a back pressure bolt (45), the back pressure bolt (45) penetrates through a through hole in the center of the back pressure ejector rod (46) from top to bottom and is contacted with the top of the steel ball (22), the bottom pressurizing device comprises a pressure chamber (51) and a pressurizing ring (50), the pressurizing ring (50) is arranged in the pressure chamber (51), a closed air pressure chamber (55) is formed between the bottom surface of the pressurizing ring (50) and the inner wall of the pressure chamber (51), the pressurizing measuring device comprises a stabilizing rod (48) and an L-shaped measuring rod (49), the lower part of the L-shaped measuring rod (49) is connected with the pressurizing ring (50), and the upper part of the L-shaped measuring rod is connected with one end of the stabilizing rod (48);
the infiltration system consists of a gas cylinder (1), a gas pressure relief valve (2), a gas pressure stabilizing machine (3), an injection chamber a and an automatic exudate monitoring and collecting device; the gas bottle (1) is communicated with a gas pressure stabilizer (3) through a gas pressure relief valve (2); a three-way ball valve a (12) and a back pressure switch (13) are also arranged between the gas pressure stabilizer (3) and the injection chamber a, a back pressure pipe (24) is connected to the three-way ball valve a (12), and the other end of the back pressure pipe (24) is communicated with the lower half chamber of the injection chamber a; the lower half chamber of the injection chamber a is communicated with a penetrating fluid input channel (39) through a three-way ball valve c (64); the gas pressure stabilizer (3) is communicated with the air pressure chamber (55) through a fourth air regulating valve (5) and an axial pressure gas three-way valve (52); the automatic monitoring and collecting device for the percolate comprises a percolate collecting device (59), a conical bottle (60), a data recorder (61), two anti-corrosion flow meters (56) and a three-way ball valve d (63);
the confining pressure system comprises an injection chamber b and an injection chamber c, and a temperature-controllable heating belt (9) is arranged outside the injection chamber c; the lower half chamber of the injection chamber b is communicated with the lower through channel (11) through a three-way ball valve b (19) and a liquid inflow three-way valve (32), and the other end of the three-way ball valve b (19) is communicated with the lower half chamber of the injection chamber c through a liquid one-way valve (18); the lower half chamber of the injection chamber c is communicated with the upper through channel (10) through another liquid one-way valve (18) and a liquid outflow three-way valve (31);
step 2, Overall set of tests
Setting J times of dry-humidity circulation, and recording any one of the J times of dry-humidity circulation as a set time X of dry-humidity circulationjJ1, 2.. J; setting I test temperatures, and recording any one of the test temperatures as a set test temperature TiI is 1, 2 … I; setting A groups of consolidation pressure, and recording any one group as the set consolidation pressure PaThe set consolidation pressure PaIncluding setting a consolidation axial pressure P1aAnd setting a consolidation confining pressure P2aAnd a is 1, 2 … a, i.e., the permeation test method of the present invention comprises J × I × a combinations;
then, carrying out a penetration test on each combination of the J multiplied by I multiplied by A, and synchronously monitoring and recording the states of temperature and stress changes of the sample after the dry-wet cycle times are reached;
specifically, the test steps of any combination are shown in step 3-step 11;
step 3, setting test parameters and recording test data
Given set humidity cycle temperature TxSetting the dry water content w1Setting the saturated water content w2And w is2≥w1
Given set liquid confining pressure PmWhere M is 1, 2 … M, and the injection pressure is set to PnN is 1, 2 … N, and in the permeation test, a liquid confining pressure P is set for eachmEach set injection pressure PnCarrying out one penetration test;
in the process of the penetration test, four sensors are installed in the flexible wall permeameter, namely a displacement sensor (47), a pH sensor (58), a conductivity sensor (57) and a mass sensor (54), wherein the displacement sensor (47) is arranged on the stabilizing rod (48), the pH sensor (58) and the conductivity sensor (57) are placed in the permeate collecting device (59), and the mass sensor (54) is placed at the bottom of the air pressure chamber (55);
in the process of the penetration test, a temperature regulator (40) is arranged and used for monitoring the temperature of the temperature-controllable heating belt (9);
in the process of carrying out the penetration test, a data recorder (61) is respectively connected with two anti-corrosion flowmeters (56), four sensors and a temperature regulator (40) to obtain real-time data, and the real-time data is automatically recorded every 1 minute;
step 4, setting the initial state of the testing device
Firstly, all valves are adjusted to be in a closed state, all channels are closed, the exhaust hole (14) and the liquid injection hole (16) are closed, and the flexible rubber membranes (15) in the three injection chambers are in contact with the top of the upper half chamber in the initial state;
the mass of the sample is weighed and recorded as the initial mass m0Calculating the water content of the sample and recording as the initial water content w0；
Then opening a liquid injection hole (16), injecting deionized water into the three injection chambers, closing the liquid injection hole (16) after the three injection chambers are filled with the deionized water, and rotating a three-way ball valve b (19) to enable the injection chamber b to be communicated with a confining pressure chamber (35) through an inflow liquid three-way valve (32) and a lower through channel (11);
step 5, install the sample (21)
Taking down a top cover (25) in the test device, sequentially installing a permeable stone (29), filter paper (6), a sample (21), the filter paper (6) and the permeable stone (29) in a rubber film (36) which is rolled into a cylinder from bottom to top, and then locking the top cover (25), a main body (34) and a base (41) to form a permeation chamber (33) with an inner closed part;
placing the test device on a pressurizing ring (50), and aligning a steel ball (22) to the center of the bottom end of a back pressure screw (45);
step 6, injecting water into the confining pressure chamber (35)
Adjusting an inflow liquid three-way valve (32) to enable a lower through channel (11) to be communicated with a water injection pump, adjusting an outflow liquid three-way valve (31) to enable an upper through channel (10) to be connected with a water bucket, starting the water injection pump to inject deionized water into a confining pressure chamber (35), and adjusting the outflow liquid three-way valve (31) to enable the confining pressure chamber (35) to be communicated with an injection chamber c through a liquid conveying pipe when the water level reaches the top of the confining pressure chamber (35) and water flows into the water bucket;
step 7, carrying out dry-humidity circulation
Step 7.1, opening the gas cylinder (1), adjusting the gas pressure relief valve (2) to enable compressed gas to flow into the gas pressure stabilizing machine (3), starting heating the temperature-controllable heating belt (9), and monitoring the temperature of the temperature by the temperature regulator (40);
step 7.2, an air regulating valve (4) at the upper end of the injection chamber c is regulated to apply micro pressure to the injection chamber c, a three-way ball valve b (19) is rotated to enable the lower half chamber of the injection chamber c to be communicated with an inflow liquid three-way valve (32), deionized water in the injection chamber c enters a confining pressure chamber (35) and flows back to the injection chamber c through an outflow liquid three-way valve (31), and continuous circulation is achieved;
step 7.3, when the temperature of the temperature-controllable heating belt (9) reaches the set dry-humidity circulating temperature TxAt that time, the mass of the sample (21) at that time was recorded and recorded as the total mass m1；
Opening all the drainage channels (27) to make the sample (21) enter an evaporation state;
step 7.4, when the water content of the sample reaches the set dry water content w1When the heating is stopped, an air regulating valve (4) for regulating the upper end of the injection chamber a applies heat to the injection chamber aAdding a constant saturation pressure PtThe sample (21) is moistened by making deionized water enter the permeation chamber (33) through the penetrating fluid input channel (39), and the same saturation pressure P is applied to the injection chamber b by adjusting an air adjusting valve (4) at the upper end of the injection chamber bt；
Step 7.5, when the water content of the sample reaches the set saturated water content w2When the method is used, one-time dry-humidity circulation is completed;
step 7.6, checking whether the set dry-humidity cycle times X are reachedjIf yes, entering step 8, otherwise, returning to step 7.1, and continuing to perform the humidity cycle;
step 8, applying axial pressure
Step 8.1, zeroing the air control valve (4) of the injection chamber a, connecting the two corrosion protection flowmeters (56) to the permeate inlet channel (39) and the permeate outlet channel (28), recording the mass of the sample (21) at that time and recording the mass as a balance mass m2；
The gas pressure stabilizer (3) applies a constant axial pressure P to the pressure chamber (51) through the axial pressure gas three-way valve (52)h，Ph＝4m2g/(πR2) Wherein R is the inner radius of the pressure chamber (51), and g is 9.8N/kg;
adjusting the back pressure screw (45) to enable the lower bottom surface of the back pressure screw (45) to be in contact with the steel ball (22), and fixing the back pressure screw by using an adjusting nut (44); the position of the stabilizer bar (48) on the L-shaped measuring rod (49) is adjusted, so that the probe of the displacement sensor (47) is in contact with the upper surface of the back-pressure screw (45);
step 8.2, adjusting the axial pressure gas three-way valve (52) to enable the air pressure chamber (55) to be communicated with the pressure stabilizer (3); the fourth air regulating valve (5) is firstly adjusted to zero and then adjusted again, and a set consolidation axial pressure P1 is applied to the air pressure chamber (55)a(ii) a An air regulating valve (4) for regulating the injection chamber (b), and a set consolidation ambient pressure P2 is applied to the ambient pressure chamber (35) through the injection chamber (b)a，P2a＞P1a(ii) a Recording the vertical deformation of the sample through a data recorder (61), and finishing the consolidation process when the vertical deformation is less than 0.01mm within 1 hour;
step 9, removing air bubbles
Step 9.1, the temperature regulator (40) will be usedThe temperature of the temperature control heating belt (9) is adjusted to be a set test temperature TiAn air regulating valve (4) for regulating the upper end of the injection chamber c and a setting consolidation confining pressure P applied to the confining pressure chamber (35) through the injection chamber ca2；
9.2, after the temperature is stabilized, adjusting an air adjusting valve (4) at the upper end of the injection chamber a, and applying an initial injection pressure P to the permeation chamber (33) through the injection chamber ad，Pd＜P2a；
Step 9.3, opening a top exhaust channel (26) and a bottom exhaust channel (38) of the test device, and removing visible air bubbles in the test sample (21) and the rubber membrane (36);
closing the top vent passage (26) and the bottom vent passage (38) after the air bubbles are removed;
step 10, injecting a permeate and developing a permeation test
Step 10.1, closing a penetrating fluid inflow channel (39), opening a liquid injection hole (16), adjusting an air adjusting valve (4) of an injection chamber a, applying pressure on the upper part of a flexible rubber membrane (15), discharging deionized water from the liquid injection hole (16), after the lower half chamber is emptied, contacting a latex membrane with the bottom of the lower half chamber of the injection chamber a, and closing the liquid injection hole (16);
step 10.2, opening an exhaust hole (14), opening a side wall back pressure switch (17), closing a back pressure switch (13), rotating a three-way ball valve a (12) to enable gas to enter a lower half chamber, applying pressure to the lower part of a flexible rubber film (15), rebounding the flexible rubber film (15) to be in contact with the top of the upper half chamber, and closing the exhaust hole (14);
step 10.3, closing a side wall back pressure switch (17), zeroing a three-way ball valve a (12), opening a liquid injection hole (16), injecting seepage liquid into the injection chamber a, closing the liquid injection hole (16) after the liquid injection chamber a is filled with the seepage liquid, opening a back pressure switch (13), and rotating the three-way ball valve a (12) to enable the gas pressure stabilizing machine (3) to be communicated with the upper half chamber of the injection chamber a;
step 10.4, the air regulating valve (4) of the injection chamber c is zeroed and then readjusted to stabilize the confining pressure in the confining pressure chamber (35) to the set liquid confining pressure Pm(ii) a An air regulating valve (4) for regulating the injection chamber (a) to stabilize the injection pressure to a set injection pressure (P)nThe permeate flows from the injection chamber a via a corrosion-resistant feed flow meter (62) and a permeate chamber feed channel (39) into the permeateA chamber (33) which then flows through a permeate outlet channel (28) and another corrosion protection outlet flow meter (56) into a permeate collection device (59);
during the test, when the penetrating fluid of the injection chamber a is exhausted, closing the penetrating fluid input channel (39), returning to the step 10.2, re-injecting the penetrating fluid, and continuing the test;
step 10.5, when the condition of stopping the penetration test is met, stopping the penetration liquid injection, automatically storing the current real-time penetration liquid output flow Q, and entering the step 11; otherwise, returning to the step 10.4 and continuing the test;
step 11, checking N set injection pressures PnIf so, returning to step 10.1 to perform the next set injection pressure Pn(ii) a permeation test; otherwise, go to step 12;
step 11, checking M set liquid confining pressures PmIf yes, returning to step 10.1 to perform next set liquid confining pressure Pm(ii) a permeation test; otherwise, go to step 12;
step 12, calculating the permeability coefficient K
Removing the sample, measuring and recording the final diameter D and the final height L of the sample;
test data in a data recorder are called, and the permeability coefficient K is calculated according to the following formula:
Figure FDA0003247212480000081
wherein, deltah is the water head difference,
Figure FDA0003247212480000082
Hwheight of water column at standard atmospheric pressure, PstandardIs 1 atm.
2. The method for the temperature-stress integrated control flexible wall permeation test under dry and wet cycles according to claim 1, wherein the permeation test termination condition is determined as follows:
setting the interval to be 1 hour, carrying out data comparison once, and recording real-time data obtained during data comparison as comparison instant data;
when the penetrating fluid is water, the conditions for terminating the penetration test are that the following conditions are simultaneously met:
(1) the ratio of the instantaneous penetrant input flow and the instantaneous penetrant output flow measured during the continuous 4 times of data comparison is 0.75-1.25;
(2) finally, the comparison instantaneous penetrant output flow measured in 4 times of continuous data comparison is between 0.75 and 1.25 times of the average flow value, and the average flow value is the average of 60 real-time penetrant output flows recorded in two data comparison intervals;
when the penetrating fluid is a heavy metal solution or an organic polluted solution, the condition for terminating the penetration test also needs to satisfy the following conditions in addition to the above regulation:
(3) comparing the difference between the instantaneous permeate output flow and the instantaneous permeate input flow to be greater than or equal to 2 times of the sample pore volume;
(4) the conductivity compared to the instantaneous permeate output is within ± 10% of the initial conductivity;
(5) the pH value of the compared instantaneous penetrating fluid output is within +/-10% of the initial pH value.
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