CN111721918A - Air-containing belt saturated soil body vertical shaft combined vacuum method precipitation test device and method - Google Patents
Air-containing belt saturated soil body vertical shaft combined vacuum method precipitation test device and method Download PDFInfo
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- CN111721918A CN111721918A CN202010606491.XA CN202010606491A CN111721918A CN 111721918 A CN111721918 A CN 111721918A CN 202010606491 A CN202010606491 A CN 202010606491A CN 111721918 A CN111721918 A CN 111721918A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/24—Earth materials
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D1/00—Investigation of foundation soil in situ
- E02D1/02—Investigation of foundation soil in situ before construction work
- E02D1/027—Investigation of foundation soil in situ before construction work by investigating properties relating to fluids in the soil, e.g. pore-water pressure, permeability
Abstract
The device comprises a test box, a water injection system, a gas injection system, a water pumping system, a vacuum pumping system and a monitoring system, wherein the water injection system, the gas injection system, the water pumping system, the vacuum pumping system and the monitoring system are connected with the test box; the water injection system supplies water to the test soil body from bottom to top to obtain a saturated test soil body; the gas injection system simulates the generation of gas in a soil body of a saturation test; the water pumping system pumps water from the test soil body and is used for testing soil body precipitation; the vacuumizing system is used for changing the pore pressure boundary of the soil body so as to generate vacuum degree in the test box. The invention also provides a test method of the vacuum method precipitation test device combined with the saturated soil vertical shaft with the gas-containing belt. In the water injection, gas injection, vacuum pumping and vertical shaft precipitation test processes, the soil pressure, sedimentation, water level, pore pressure, water content, water pumping amount, air pumping amount and vacuum degree of a test soil body are monitored, so that the precipitation effect under different closed gas bag occurrence conditions and different precipitation schemes can be simulated and analyzed.
Description
Technical Field
The invention relates to the field of shaft combined vacuum method precipitation tests, in particular to a device and a method for a shaft combined vacuum method precipitation test of a saturated soil body with a gas-containing belt.
Background
Saturated soil bodies containing closed gas pockets exist in the field of geotechnical engineering, such as saturated soft soil foundations with high organic matters and high water level refuse landfills. For saturated soft soil with high organic matter content, methane formed by degrading organic matters is deposited in the saturated soft soil, and the existence of the enclosed gas can have great influence on the safety of tunneling, deep foundation construction and the like. The problem of high water level of leachate generally exists in a refuse landfill, landfill gas formed by degrading degradable refuse can be deposited in a landfill body below the water level, and the existence of the landfill gas can aggravate the problems of unstable and smooth flow of a pile, underground water and soil pollution and incapability of effectively collecting the landfill gas caused by the high leachate water level. Therefore, it is necessary to reduce the water content of the saturated soil containing the closed gas-filled belts, and to eliminate or reduce the silting of the closed gas-filled belts, thereby preventing and controlling the above-mentioned geotechnical engineering problems.
An indoor large-scale model test system provides a good way for researching the precipitation mechanism and application of saturated soil containing closed gas pockets. At present, all indoor large-scale precipitation model test systems aim at saturated soil bodies without closed gas-bag belts, and lack the indoor large-scale precipitation model test systems aiming at the saturated soil bodies with the closed gas-bag belts. In addition, in consideration of the mutual influence of the precipitation process and the development process of the closed air bag, it is necessary to disclose the influence rule of the vacuum pumping on the acceleration of the diffusion of the closed air bag and the improvement of the precipitation effect in the above test. Therefore, the test system is required to have the functions of simulating the deposition and diffusion of the closed air bag and the precipitation implemented by combining a vacuum method.
Disclosure of Invention
In order to overcome the problems, the invention provides a device and a method for testing precipitation of a saturated soil body with a gas-containing bag belt by a vertical shaft combined vacuum method.
The invention provides a combined vacuum precipitation test device for a shaft of a saturated soil body with a gas-containing bag belt, which comprises a test box, a water injection system, a gas injection system, a pumping system, a vacuumizing system and a monitoring system, wherein the water injection system is connected with the water injection system;
the test box is a sealed box body, and a test soil body is filled in the test box; the lower parts of two side walls of the test box are respectively provided with a gas injection hole and a water injection hole, the upper parts of the two side walls of the test box are respectively symmetrically provided with a first overflow hole and a second overflow hole, and the top surface of the test box is provided with an air suction hole, a water suction hole and a wire outlet hole;
the water injection system is connected with the test box through a water injection hole and supplies water to the test soil body from bottom to top to obtain a saturated test soil body; the gas injection system is connected with the test box through a gas injection hole so as to simulate the generation of gas in a soil body in a saturation test; the water pumping system is connected with the test box through the water pumping hole, pumps water from the test soil body and is used for testing the precipitation of the soil body; the vacuumizing system is connected with the test box through the air suction hole and is used for changing the pore pressure boundary of the soil body so as to generate vacuum degree in the test box;
the water injection system comprises a water injection bucket, a water injection pipe network is arranged at the bottom in the test box and connected with the water injection bucket through a water injection pipe, a water injection valve is arranged on the water injection pipe, and a first overflow valve and a second overflow valve are respectively arranged on the first overflow hole and the second overflow hole;
the gas injection system comprises a blowing fan, a gas injection pipe network is arranged at the bottom in the test box and is positioned above the water injection pipe network; the gas injection pipe network is connected with a gas blowing fan through a gas injection pipe; a gas injection valve, a first pressure gauge, a first regulating valve and a first gas flowmeter are sequentially arranged on the gas injection pipe from one end close to the test box to one end far away from the test box;
the water pumping system comprises a peristaltic pump, a vertical shaft is arranged in the test box, and the vertical shaft is vertically embedded in the test soil body; the vertical shaft is connected with the water absorption end of the peristaltic pump through a water pumping pipe, and the water outlet end of the peristaltic pump is connected with the water injection barrel through a pipeline;
the vacuum pumping system comprises an air exhaust fan and a Y-shaped air exhaust pipe, wherein the Y-shaped air exhaust pipe consists of a first branch pipe, a second branch pipe and a main pipeline; the air exhaust fan is connected to the end of the first branch pipe and is connected with the test box through an air exhaust pipe, and an air exhaust valve is arranged on the first branch pipe; the second branch pipe is provided with an exhaust valve and a second gas flow meter, and the exhaust valve is positioned close to the main pipeline; an air suction valve, a second pressure gauge and a second regulating valve are sequentially arranged on the main pipeline from one end close to the test box to one end far away from the test box;
the monitoring system comprises a first pressure gauge, a first gas flow gauge, a second pressure gauge, a strain type soil pressure box, a strain type pore water pressure sensor, a soil moisture sensor TDR and a multichannel data acquisition instrument, wherein the strain type soil pressure box, the strain type pore water pressure sensor and the soil moisture sensor TDR are buried in test soil of the test box respectively, and the strain type soil pressure box, the strain type pore water pressure sensor and the soil moisture sensor TDR are connected with the multichannel data acquisition instrument through signal transmission lines.
Furthermore, the test box comprises a box body and a top cover, wherein the top of the box body is provided with an opening, the interior of the box body is hollow, and the box body consists of peripheral side plates and a bottom plate; a rubber pad is arranged between the top cover and the box body, and the top cover and the box body are connected through bolts and are in sealing fit.
Furthermore, the water injection pipe network is arranged in a shape like a Chinese character tian, and the plane of the water injection pipe network is parallel to the plane of the bottom surface of the test box; the pipeline wall of the water injection pipe network is provided with through holes, and the outer side of the pipeline wall of the water injection pipe network is wrapped with geotechnical cloth for preventing a test soil body from entering the interior of the water injection pipe network.
Furthermore, the gas injection pipe network is arranged in a cross shape, and the plane of the gas injection pipe network is parallel to the plane of the bottom surface of the test box; the pipeline wall of the gas injection pipe network is provided with through holes, and the outer side of the pipeline wall of the gas injection pipe network is wrapped with geotechnical cloth for preventing a test soil body from entering the inside of the gas injection pipe network.
Furthermore, the vertical shaft comprises an inner pipe, the top end of the inner pipe is connected with a water pumping nozzle used for being connected with a water pumping pipe, and the outer side of the inner pipe is sleeved with an outer pipe; the bottom of the outer pipe is sealed, through holes are uniformly distributed in the pipe wall of the outer pipe, and the outer side of the pipe wall of the outer pipe comprises geotechnical cloth used for testing soil to enter a vertical shaft.
Further, the bottom end of the inner tube is 10mm higher than the bottom end of the outer tube.
Furthermore, a sealing piece is arranged in the wire outlet hole, and a fine hole for the signal transmission line to penetrate out is arranged in the sealing piece.
The invention provides a test method of a combined vacuum precipitation test device for a saturated soil body vertical shaft with a gas-containing belt, which comprises the following steps:
step 1, firstly arranging a water injection pipe network at the bottom of a test box, then filling soil into the test box layer by layer, and tamping layer by layer; arranging a gas injection pipe network at a set height position, arranging a vertical shaft by depending on the side wall of the test box, and then continuously filling a soil body until the completion of the arrangement; the strain type soil pressure box, the strain type pore water pressure sensor and the soil moisture sensor TDR are put in the soil filling process according to the pre-designed positions; signal transmission lines of the strain type soil pressure box, the strain type pore water pressure sensor and the soil moisture sensor TDR penetrate out of a sealing piece of the wire outlet hole, the top cover is covered, the top cover is tightly connected with the box body through a test box bolt, and the penetrated signal transmission lines are connected with the multi-channel data acquisition instrument;
step 2, standing for 24 hours, and then recording initial readings of all monitoring instruments; after the initial reading and recording are finished, injecting water into the water injection barrel; opening the water injection valve, the first overflow valve and the second overflow valve, continuously injecting water into the water injection barrel to keep the water level of the water injection barrel, and simultaneously injecting water into the soil body through the water injection pipe network; when water flows out of the first overflow valve and the second overflow valve, marking the end of water injection, stopping injecting water into the water injection barrel, enabling the water level in the water injection barrel to be consistent with the water level in the soil body, and observing scales on the inner wall of the water injection barrel to obtain the water level height in the soil body; when the water injection is finished, closing the water injection valve, closing the first overflow valve and the second overflow valve, and emptying the residual water in the water injection bucket;
step 3, after the water injection is finished, the soil body is saturated; standing the soil body for 48 hours, opening an air suction valve, a second regulating valve, an air suction valve and an air suction fan in the vacuum pumping system during standing, setting a higher vacuum degree through the second regulating valve, and vacuumizing the test box to saturate the test soil body; keeping the continuous vacuum pumping during the standing period, and reading the vacuum degree through a second pressure gauge;
step 4, after the test soil body is saturated, closing a valve and an air exhaust fan which are opened in the vacuum pumping system; carrying out a test for simulating a saturated foundation containing a closed gas bag in the precipitation treatment of a common shaft, wherein the test needs to open a first regulating valve, a gas injection valve, a gas extraction valve, a second regulating valve, an exhaust valve and a blowing fan in a gas injection system, the required gas injection rate is set through the first regulating valve, gas is injected into a test soil body through a gas injection pipe network, and gas exhausted from the test soil body is discharged from the gas extraction valve and the exhaust valve and is collected; the first gas flowmeter measures the gas injection quantity, the gas injection rate is calculated by combining the gas injection quantity with the gas injection time, the first pressure gauge measures the gas injection pressure, the second pressure gauge measures the exhaust pressure, and the second gas flowmeter measures the collected exhaust quantity; after the gas injection is finished, closing the first regulating valve and the gas injection valve, standing for a period of time according to the test requirement, and closing the exhaust valve after the standing is finished;
step 5, opening an air suction valve, a second regulating valve, an air suction valve and an air suction fan in the vacuum pumping system, setting the required vacuum degree through the second regulating valve, and pumping vacuum in the test chamber; meanwhile, a peristaltic pump is started to pump water from the vertical shaft, and the pumped water is discharged into a water injection bucket to be collected;
and 6, repeating the steps 1-5, and setting the gas injection rate and the vacuum degree required by the next stage in the step 5 until the test is finished.
The invention has the beneficial effects that:
(1) the water injection system can set overflow valves with different heights on the side wall of the test box according to requirements, and the requirements of controlling the height of the injection water level can be met by opening the valves.
(2) The insufflation system sets different modes of gas injection, including different insufflation pressures and insufflation rates, and measures the pressure and volume of the exiting gas.
(3) The pumping system can set different pumping rates and measure the amount of pumping during shaft precipitation.
(4) The vacuum pumping system can set different vacuum degrees.
Drawings
Fig. 1 is a schematic structural view of a test chamber.
Fig. 2 is a schematic diagram of the system of the present invention.
Fig. 3 is a schematic diagram of the internal system of the test chamber.
Fig. 4 is a schematic structural diagram of a water injection pipe network.
FIG. 5 is a schematic diagram of a gas injection pipe network.
Fig. 6 is a schematic diagram of the construction of a shaft.
Description of reference numerals: a test chamber 1; a top cover 1-1; 1-2 of a test box bolt; 1-3 of a side plate; 1-4 of a bottom plate; 1-5 parts of gas injection holes; 1-6 parts of water injection holes; first spillway holes 1-7; a second overflow hole 1-8; 1-9 parts of water pumping holes; 1-10 parts of air extraction holes; wire outlet holes 1-11; 1-12 parts of rubber pad; a water injection system 2; 2-1 of a water injection valve; 2-2 parts of a water injection pipe network; 2-3 parts of a water injection pipe; 2-4 parts of a water injection barrel; a first overflow valve 2-5; 2-6 parts of a second overflow valve; a gas injection system 3; a gas injection valve 3-1; 3-2 parts of a gas injection pipe network; 3-3 parts of a gas injection pipe; a first regulating valve 3-4; 3-5 of a blowing fan; 3-6 parts of an exhaust valve; a water pumping system 4; 4-1 of a water pumping pipe; a shaft 4-2; 4-3 of a peristaltic pump; a vacuum pumping system 5; 5-1 of an air extraction valve; a second regulating valve 5-2; 5-3 of an exhaust pipe; 5-4 parts of an air extraction valve; 5-5 of an air exhaust fan; a first pressure gauge 6-1; a first gas flow meter 6-2; a second gas flow meter 6-3; and 6-4 parts of a second pressure gauge.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are only some embodiments, but not all embodiments, of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the description of the present invention, it should be noted that the orientations or positional relationships indicated as the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., appear based on the orientations or positional relationships shown in the drawings only for the convenience of describing the present invention and simplifying the description, but not for indicating or implying that the referred devices or elements must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" as appearing herein are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the present invention, it should be noted that, unless otherwise explicitly stated or limited, the terms "mounted," "connected," and "connected" should be interpreted broadly, e.g., as being fixed or detachable or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
Referring to the attached drawings, the vertical shaft combined vacuum precipitation test device containing the closed gas-bag saturated soil comprises a test box 1, a water injection system 2, a gas injection system 3, a water pumping system 4, a vacuum pumping system 5 and a monitoring system 6;
the test box 1 is a sealed box body, and a test soil body is filled in the test box 1; the test box 1 comprises a box body with an opening at the top and a hollow top cover 1-1, and the box body consists of peripheral side plates 1-3 and a bottom plate 1-4; a rubber pad 1-12 is arranged between the top cover 1-1 and the box body, and the top cover 1-1 and the box body are connected and matched in a sealing way through a test box bolt 1-2; the lower parts of two side walls of the test box 1 are respectively provided with a gas injection hole 1-5 and a water injection hole 1-6, the upper parts of the two side walls of the test box 1 are respectively symmetrically provided with a first overflow hole 1-7 and a second overflow hole 1-8, and the top cover 1-1 is provided with an air suction hole 1-10, a water pumping hole 1-9 and a wire outlet hole 1-11;
the water injection system 2 is connected with the test box 1 through water injection holes 1-6 and supplies water to the test soil body from bottom to top to obtain a saturated test soil body; the gas injection system 3 is connected with the test box 1 through gas injection holes 1-5 so as to simulate the generation of gas in a saturated test soil body; the water pumping system 4 is connected with the test box 1 through water pumping holes 1-9, pumps water from a test soil body and is used for testing soil body precipitation; the vacuumizing system 5 is connected with the test box 1 through the air pumping holes 1-10 and used for changing the pore pressure boundary of the soil body so as to generate vacuum degree in the test box;
the water injection system 2 comprises water injection buckets 2-4, a water injection pipe network 2-2 is arranged at the bottom in the test box 1, the water injection pipe network 2-2 is arranged in a field shape, and the plane of the water injection pipe network 2-2 is parallel to the plane of the bottom surface of the test box 1; the pipeline wall of the water injection pipe network 2-2 is provided with through holes, and the outer side of the pipeline wall of the water injection pipe network 2-2 is wrapped with geotechnical cloth for preventing a test soil body from entering the water injection pipe network 2-2; the water injection pipe network 2-2 is connected with a water injection barrel 2-4 through a water injection pipe 2-3, a water injection valve 2-1 is arranged on the water injection pipe 2-3, and a first overflow valve 2-5 and a second overflow valve 2-6 are respectively arranged on a first overflow hole 1-7 and a second overflow hole 1-8;
the gas injection system 3 comprises a blowing fan 3-5, a gas injection pipe network 3-2 is arranged at the bottom in the test box 1, and the gas injection pipe network 3-2 is positioned above the water injection pipe network 2-2; the gas injection pipe network 3-2 is arranged in a cross shape, and the plane of the gas injection pipe network 3-2 is parallel to the plane of the bottom surface of the test box 1; the pipeline wall of the gas injection pipe network 3-2 is provided with through holes, and the outer side of the pipeline wall of the gas injection pipe network 3-2 is wrapped with geotechnical cloth for preventing a test soil body from entering the interior of the gas injection pipe network 3-2; the gas injection pipe network 3-2 is connected with a blowing fan 3-5 through a gas injection pipe 3-3; a gas injection valve 3-1, a first pressure gauge 6-1, a first regulating valve 3-4 and a first gas flowmeter 6-2 are sequentially arranged on the gas injection pipe 3-3 from one end close to the test box 1 to one end far away from the test box 1;
the pumping system 4 comprises a peristaltic pump 4-3, a vertical shaft 4-2 is arranged in the test box 1, and the vertical shaft 4-2 is vertically embedded in the test soil body; the vertical shaft 4-2 comprises an inner pipe 4-2-2, the top end of the inner pipe 4-2-2 is connected with a water pumping nozzle 4-2-3 used for being connected with a water pumping pipe 4-1, the outer side of the inner pipe 4-2-2 is sleeved with an outer pipe 4-2-1, and the bottom end of the inner pipe 4-2-2 is higher than the bottom end of the outer pipe 4-2-1 by about 10 mm; the bottom of the outer pipe 4-2-1 is closed, through holes are uniformly distributed on the pipe wall of the outer pipe 4-2-1, and the outer side of the pipe wall of the outer pipe 4-2-1 comprises geotechnical cloth used for enabling a test soil body to enter the vertical shaft 4-2; the vertical shaft 4-2 is connected with the water suction end of the peristaltic pump 4-3 through a water suction pipe 4-1, and the water outlet end of the peristaltic pump 4-3 is connected with the water injection barrel 2-4 through a pipeline;
the vacuum pumping system 5 comprises an air exhaust fan 5-5 and a Y-shaped air exhaust pipe 5-3, wherein the Y-shaped air exhaust pipe 5-3 consists of a first branch pipe, a second branch pipe and a main pipeline; an air exhaust fan 5-5 is connected to the end of the first branch pipe and is connected with the test box 1 through an air exhaust pipe 5-3, and an air exhaust valve 5-4 is arranged on the first branch pipe; the second branch pipe is provided with an exhaust valve 3-6 and a second gas flowmeter 6-3, and the exhaust valve 3-6 is positioned close to the main pipeline; an air suction valve 5-1, a second pressure gauge 6-4 and a second regulating valve 5-2 are sequentially arranged on the main pipeline from one end close to the test box 1 to one end far away from the test box 1;
the monitoring system comprises a first pressure gauge 6-1, a first gas flow gauge 6-2, a second gas flow gauge 6-3, a second pressure gauge 6-4, a strain type soil pressure cell, a strain type pore water pressure sensor, a soil moisture sensor TDR and a multichannel data acquisition instrument, wherein the strain type soil pressure cell, the strain type pore water pressure sensor and the soil moisture sensor TDR are respectively embedded in the test soil of the test box 1, and the strain type soil pressure cell, the strain type pore water pressure sensor and the soil moisture sensor TDR are connected with the multichannel data acquisition instrument through signal transmission lines. And sealing parts are arranged in the wire outlet holes 1-11, and fine holes for the signal transmission lines to penetrate out are arranged in the sealing parts.
The test method of the vacuum method precipitation test device combined with the vertical shaft of the saturated soil body with the gas-containing belt comprises the following steps:
step 1, arranging a water injection pipe network 2-2 at the bottom of a test box 1, then filling soil into the test box 1 layer by layer, and tamping layer by layer; arranging a gas injection pipe network 3-2 at a set height position, arranging a vertical shaft 4-2 by depending on the side wall of the test box, and then continuously filling a soil body until the completion of the arrangement; the strain type soil pressure box, the strain type pore water pressure sensor and the soil moisture sensor TDR are put in the soil filling process according to the pre-designed positions; signal transmission lines of the strain type soil pressure box, the strain type pore water pressure sensor and the soil moisture sensor TDR penetrate out of a sealing piece of the wire outlet hole 1-11, a top cover 1-1 is covered, the top cover 1-1 is tightly connected with the box body through a test box bolt 1-2, and the penetrated signal transmission lines are connected with a multi-channel data acquisition instrument;
step 2, standing for 24 hours, and then recording initial readings of all monitoring instruments; after the initial reading and recording are finished, injecting water into a water injection barrel 2-4; opening a water injection valve 2-1, a first water overflow valve 2-5 and a second water overflow valve 2-6, continuously injecting water into the water injection barrel 2-4 to keep the water level of the water injection barrel 2-4, and simultaneously injecting water from the water injection barrel 2-4 into a soil body through a water injection pipe network 2-2; when water flows out of the first overflow valve 2-5 and the second overflow valve 2-6, the end of water injection is marked, at the moment, water injection into the water injection barrel 2-4 is stopped, the water level in the water injection barrel is consistent with the water level in the soil body, and scales on the inner wall of the water injection barrel 2-4 are observed to obtain the water level height in the soil body; when the water injection is finished, closing the water injection valve 2-1, closing the first overflow valve 2-5 and the second overflow valve 2-6, and emptying the residual water in the water injection bucket 2-4;
step 3, after the water injection is finished, the soil body is saturated; standing the soil body for 48 hours, opening an air suction valve 5-1, a second regulating valve 5-2, an air suction valve 5-4 and an air suction fan 5-5 in a vacuum pumping system 5 during standing, setting a higher vacuum degree through the second regulating valve 5-2, and vacuumizing the test box 1 to saturate the test soil body; keeping the continuous vacuum pumping during the standing period, and reading the vacuum degree through a second pressure gauge 6-4;
step 4, after the test soil body is saturated, closing a valve and an air exhaust fan 5-5 which are opened in the vacuum-pumping system 5; carrying out a test for simulating a saturated foundation containing a closed gas bag in the precipitation treatment of a common shaft, wherein the test needs to open a first regulating valve 3-4, a gas injection valve 3-1, a gas extraction valve 5-1, a second regulating valve 5-2, a gas exhaust valve 3-6 and a blowing fan 3-5 in a gas injection system 3, set the required gas injection rate through the first regulating valve 3-4, inject gas into a test soil body through a gas injection pipe network 3-2, and discharge and collect gas exhausted from the test soil body from the gas extraction valve 5-1 and the gas exhaust valve 3-6; the first gas flowmeter 6-2 measures the gas injection amount, the gas injection rate is calculated by combining the gas injection amount with the gas injection time, the first pressure gauge 6-1 measures the gas injection pressure, the second pressure gauge 6-4 measures the exhaust pressure, and the second gas flowmeter 6-3 measures the collected exhaust amount; after gas injection is finished, closing the first regulating valve 3-4 and the gas injection valve 3-1, standing for a period of time according to test requirements, and closing the exhaust valve 3-6 after standing is finished;
step 5, opening an air extraction valve 5-1, a second regulating valve 5-2, an air extraction valve 5-4 and an air extraction fan 5-5 in the vacuum-pumping system 5, setting the required vacuum degree through the second regulating valve 5-2, and vacuumizing the test chamber 1; meanwhile, a peristaltic pump 4-3 is started to pump water in a vertical shaft 4-2, and the pumped water is discharged into a water injection bucket 2-4 to be collected;
and 6, repeating the steps 1-5, and setting the gas injection rate and the vacuum degree required by the next stage in the step 5 until the test is finished.
A simulation shaft combined vacuum method (different vacuum degrees) is used for processing a saturated foundation test containing a closed gas-bag zone, and all the operations of opening a cover, filling soil, burying a sensor, closing the cover and injecting water into a saturated soil body are repeated; in the test, firstly, an adjusting valve 3-4, an air injection valve 3-1, an air extraction valve 5-1, a second adjusting valve 5-2, an exhaust valve 3-6 and an air blowing fan 3-5 in an air injection system 3 are opened, the first 3-4 of the adjusting valves is used for setting the required air injection rate, air is injected into the soil body through an air injection pipe network 3-2, and gas exhausted from the soil body is exhausted from the air extraction valve 5-1 and the exhaust valve 3-6 and is collected; the first gas flowmeter 6-2 can measure the gas injection amount, the gas injection rate can be calculated by combining the gas injection amount with the gas injection time, the first pressure gauge 6-1 can measure the gas injection pressure, the second pressure gauge 6-4 can measure the exhaust pressure, and the second gas flowmeter 6-3 can measure the collected exhaust amount; after gas injection is finished, closing the first regulating valve 3-4 and the gas injection valve 3-1, standing for a period of time according to test requirements, and closing the exhaust valve 3-6 after standing is finished; repeating the previous vacuumizing and water pumping operations to complete a group of tests; all the operations of opening the cover, filling soil, embedding a sensor, closing the cover and injecting water to saturate soil are repeated, the gas injection rate required by the next stage is set, the vacuum degree required by the next stage is set through a second regulating valve 5-2, and then the water is pumped by a vertical shaft 4-2; and repeating the above operation steps until the test is completed.
In the test process, the data of the strain type soil pressure box, the strain type pore water pressure sensor and the TDR are recorded by the multi-channel data acquisition instrument, so that the changes of soil pressure, water level, pore pressure and water content can be obtained; the top cover 1-1 of the test box 1 is opened, so that the soil body settlement after the test can be directly measured; the change of the water pumping quantity can be measured by the water quantity collected by the water injection barrel 2-4; and the difference value of the monitoring readings of the first gas flow meter 6-2 and the second gas flow meter 6-3 under a certain group of tests is the air extraction amount in the precipitation process.
A normal vertical shaft and a vertical shaft combined vacuum method (different vacuum degrees) are used for carrying out a precipitation test on a saturated soil body containing a closed gas-bag, and the influence rule of the vacuum degree on accelerating diffusion of the closed gas-bag and improving the precipitation effect is simulated and analyzed under different occurrence modes of the closed gas-bag by combining monitoring of soil body soil pressure, sedimentation, water level, pore pressure, water content, water pumping amount, air pumping amount and vacuum degree in the test process.
The embodiments described in this specification are merely illustrative of implementations of the inventive concept and the scope of the present invention should not be considered limited to the specific forms set forth in the embodiments but rather by the equivalents thereof as may occur to those skilled in the art upon consideration of the present inventive concept.
Claims (8)
1. The vacuum method precipitation test device is united to saturated soil body shaft in gas-containing band, its characterized in that: comprises a test box (1), a water injection system (2), a gas injection system (3), a water pumping system (4), a vacuum pumping system (5) and a monitoring system;
the test box (1) is a sealed box body, and a test soil body is filled in the test box (1); the lower parts of two side walls of the test box (1) are respectively provided with a gas injection hole (1-5) and a water injection hole (1-6), the upper parts of the two side walls of the test box (1) are respectively and symmetrically provided with a first overflow hole (1-7) and a second overflow hole (1-8), and the top surface of the test box is provided with a gas extraction hole (1-10), a water pumping hole (1-9) and a wire outlet hole (1-11);
the water injection system (2) is connected with the test box (1) through water injection holes (1-6) and supplies water to the test soil body from bottom to top to obtain a saturated test soil body; the gas injection system (3) is connected with the test box (1) through gas injection holes (1-5) to simulate the generation of gas in a saturation test soil body; the water pumping system (4) is connected with the test box (1) through water pumping holes (1-9) and pumps water from a test soil body for precipitation of the test soil body; the vacuum pumping system (5) is connected with the test box (1) through the air pumping holes (1-10) and is used for changing the pore pressure boundary of the soil body so as to generate vacuum degree in the test box;
the water injection system (2) comprises water injection buckets (2-4), a water injection pipe network (2-2) is arranged at the bottom in the test box (1), the water injection pipe network (2-2) is connected with the water injection buckets (2-4) through water injection pipes (2-3), water injection valves (2-1) are arranged on the water injection pipes (2-3), and a first overflow valve (2-5) and a second overflow valve (2-6) are respectively arranged on the first overflow hole (1-7) and the second overflow hole (1-8);
the gas injection system (3) comprises a blowing fan (3-5), a gas injection pipe network (3-2) is arranged at the bottom in the test box (1), and the gas injection pipe network (3-2) is positioned above the water injection pipe network (2-2); the gas injection pipe network (3-2) is connected with a blowing fan (3-5) through a gas injection pipe (3-3); a gas injection valve (3-1), a first pressure gauge (6-1), a first regulating valve (3-4) and a first gas flowmeter (6-2) are sequentially arranged on the gas injection pipe (3-3) from one end close to the test box (1) to one end far away from the test box (1);
the water pumping system (4) comprises a peristaltic pump (4-3), a vertical shaft (4-2) is arranged in the test box (1), and the vertical shaft (4-2) is vertically embedded in the test soil body; the vertical shaft (4-2) is connected with the water absorption end of the peristaltic pump (4-3) through a water pumping pipe (4-1), and the water outlet end of the peristaltic pump (4-3) is connected with the water injection barrel (2-4) through a pipeline;
the vacuum pumping system (5) comprises an air exhaust fan (5-5) and a Y-shaped air exhaust pipe (5-3), wherein the Y-shaped air exhaust pipe (5-3) consists of a first branch pipe, a second branch pipe and a main pipeline; an air exhaust fan (5-5) is connected to the end of the first branch pipe and is connected with the test box (1) through an air exhaust pipe (5-3), and an air exhaust valve (5-4) is arranged on the first branch pipe; an exhaust valve (3-6) and a second gas flow meter (6-3) are arranged on the second branch pipe, and the exhaust valve (3-6) is positioned close to the main pipeline; an air suction valve (5-1), a second pressure gauge (6-4) and a second regulating valve (5-2) are sequentially arranged on the main pipeline from one end close to the test box (1) to one end far away from the test box (1);
the monitoring system comprises a first pressure gauge (6-1), a first gas flow gauge (6-2), a second gas flow gauge (6-3), a second pressure gauge (6-4), a strain soil pressure cell, a strain pore water pressure sensor, a soil moisture sensor (TDR) and a multichannel data acquisition instrument, wherein the strain soil pressure cell, the strain pore water pressure sensor and the soil moisture sensor (TDR) are buried in the test soil body of the test box (1) respectively, and the strain soil pressure cell, the strain pore water pressure sensor and the soil moisture sensor (TDR) are connected with the multichannel data acquisition instrument through signal transmission lines.
2. The test device for the precipitation of the saturated soil shaft of the air-containing belting according to claim 1 by the vacuum method, wherein: the test box (1) comprises a box body with an opening at the top and a hollow top cover, and the box body consists of peripheral side plates (1-3) and a bottom plate (1-4); a rubber pad (1-12) is arranged between the top cover (1-1) and the box body, and the top cover (1-1) and the box body are connected through bolts and are in sealing fit.
3. The test device for the precipitation of the saturated soil shaft of the air-containing belting according to claim 1 by the vacuum method, wherein: the water injection pipe network (2-2) is arranged in a field shape, and the plane of the water injection pipe network (2-2) is parallel to the plane of the bottom surface of the test box (1); the pipeline wall of the water injection pipe network (2-2) is provided with through holes, and the outer side of the pipeline wall of the water injection pipe network (2-2) is wrapped with geotechnical cloth for preventing a test soil body from entering the water injection pipe network (2-2).
4. The test device for the precipitation of the saturated soil shaft of the air-containing belting according to claim 1 by the vacuum method, wherein: the gas injection pipe network (3-2) is arranged in a cross shape, and the plane of the gas injection pipe network (3-2) is parallel to the plane of the bottom surface of the test box (1); the pipeline wall of the gas injection pipe network (3-2) is provided with through holes, and the outer side of the pipeline wall of the gas injection pipe network (3-2) is wrapped with geotextile for preventing test soil from entering the gas injection pipe network (3-2).
5. The test device for the precipitation of the saturated soil shaft of the air-containing belting according to claim 1 by the vacuum method, wherein: the vertical shaft (4-2) comprises an inner pipe (4-2-2), the top end of the inner pipe (4-2-2) is connected with a water pumping nozzle (4-2-3) used for being connected with a water pumping pipe (4-1), and the outer side of the inner pipe (4-2-2) is sleeved with an outer pipe (4-2-1); the bottom of the outer pipe (4-2-1) is closed, through holes are uniformly distributed on the pipe wall of the outer pipe (4-2-1), and geotechnical cloth used for enabling test soil to enter the vertical shaft (4-2) is arranged on the outer side of the pipe wall of the outer pipe (4-2-1).
6. The test device for the precipitation of the saturated soil shaft with the air-containing belts by the vacuum method in combination with the air-containing belts as claimed in claim 5, wherein: the bottom end of the inner pipe (4-2-2) is 10mm higher than the bottom end of the outer pipe (4-2-1).
7. The test device for the precipitation of the saturated soil shaft of the air-containing belting according to claim 1 by the vacuum method, wherein: and sealing parts are arranged in the wire outlet holes (1-11), and fine holes for the signal transmission lines to penetrate out are arranged in the sealing parts.
8. A test method based on the combined vacuum method precipitation test device for the saturated soil shaft with the gas-containing belts according to any one of claims 1 to 7 is characterized by comprising the following steps:
step 1, arranging a water injection pipe network (2-2) at the bottom of a test box (1), then filling soil into the test box (1) layer by layer, and tamping layer by layer; arranging a gas injection pipe network (3-2) at a set height position, arranging a vertical shaft (4-2) by depending on the side wall of the test box, and then continuously filling a soil body until the completion of the arrangement; the strain type soil pressure box, the strain type pore water pressure sensor and the soil moisture sensor TDR are put in the soil filling process according to the pre-designed positions; signal transmission lines of the strain type soil pressure box, the strain type pore water pressure sensor and the soil moisture sensor TDR penetrate out of a sealing piece of the wire outlet hole (1-11), a top cover (1-1) is covered, the top cover (1-1) is tightly connected with the box body through a test box bolt (1-2), and the penetrated signal transmission lines are connected with a multi-channel data acquisition instrument;
step 2, standing for 24 hours, and then recording initial readings of all monitoring instruments; after the initial reading and recording are finished, water is injected into the water injection barrel (2-4); opening a water injection valve (2-1), a first overflow valve (2-5) and a second overflow valve (2-6), continuously injecting water into the water injection barrel (2-4) to keep the water level of the water injection barrel (2-4), and simultaneously injecting water into the soil body from the water injection barrel (2-4) through a water injection pipe network (2-2); when water flows out of the first overflow valve (2-5) and the second overflow valve (2-6), marking that water injection is finished, stopping injecting water into the water injection barrel (2-4), wherein the water level in the water injection barrel is consistent with the water level in the soil body, and observing scales on the inner wall of the water injection barrel (2-4) to obtain the water level height in the soil body; when the water injection is finished, closing the water injection valve (2-1), closing the first overflow valve (2-5) and the second overflow valve (2-6), and emptying the residual water in the water injection bucket (2-4);
step 3, after the water injection is finished, the soil body is saturated; standing the soil body for 48 hours, opening an air suction valve (5-1), a second regulating valve (5-2), an air suction valve (5-4) and an air suction fan (5-5) in a vacuum pumping system (5) during standing, setting a higher vacuum degree through the second regulating valve (5-2), and vacuumizing the test box (1) to saturate the test soil body; keeping the continuous vacuum pumping during the standing period, and reading the vacuum degree through a second pressure gauge (6-4);
step 4, after the test soil body is saturated, closing a valve and an air exhaust fan (5-5) which are opened in the vacuum-pumping system (5); carrying out a test for simulating a saturated foundation containing a closed gas bag in the precipitation treatment of a common shaft, wherein the test needs to open a first regulating valve (3-4), a gas injection valve (3-1), an air extraction valve (5-1), a second regulating valve (5-2), an exhaust valve (3-6) and a blowing fan (3-5) in a gas injection system (3), set the required gas injection rate through the first regulating valve (3-4), inject gas into a test soil body through a gas injection pipe network (3-2), and exhaust gas from the test soil body is discharged from the air extraction valve (5-1) and the exhaust valve (3-6) and collected; the first gas flowmeter (6-2) measures the gas injection amount, the gas injection rate is calculated by combining the gas injection amount with the gas injection time, the first pressure gauge 6-1 measures the gas injection pressure, the second pressure gauge (6-4) measures the exhaust pressure, and the second gas flowmeter (6-3) measures the collected exhaust amount; after the gas injection is finished, closing the first regulating valve (3-4) and the gas injection valve (3-1), standing for a period of time according to the test requirement, and closing the exhaust valve (3-6) after the standing is finished;
step 5, opening an air suction valve (5-1), a second regulating valve (5-2), an air suction valve (5-4) and an air suction fan (5-5) in the vacuum pumping system (5), setting the required vacuum degree through the second regulating valve (5-2), and vacuumizing the test box (1); meanwhile, a peristaltic pump (4-3) is started to pump water through the vertical shaft (4-2), and the pumped water is discharged into a water injection bucket (2-4) to be collected;
and 6, repeating the steps 1-5, and setting the gas injection rate and the vacuum degree required by the next stage in the step 5 until the test is finished.
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