CN112326921A

CN112326921A - Multifunctional frost heaving test system and test method thereof

Info

Publication number: CN112326921A
Application number: CN202010937471.0A
Authority: CN
Inventors: 曹亚鹏; 李国玉; 周志伟; 王新斌; 柴明堂; 张军; 郭腾
Original assignee: Northwest Institute of Eco Environment and Resources of CAS
Current assignee: Northwest Institute of Eco Environment and Resources of CAS
Priority date: 2020-09-08
Filing date: 2020-09-08
Publication date: 2021-02-05

Abstract

The invention discloses a multifunctional frost heaving test system and a test method thereof, wherein the test system comprises a support frame, a test barrel body arranged on the support frame and used for storing a soil sample, a temperature control system for controlling the temperature of the soil sample, a force application system for applying constant pressure or infinite rigidity to the soil sample through the top of the test barrel body, a water supplementing non-pressure system for supplementing water into the soil sample through the lower part of the test barrel body and a detection system. The invention can carry out multi-condition coupling test and has high integration level.

Description

Multifunctional frost heaving test system and test method thereof

Technical Field

The invention relates to the technical field of frozen soil research, in particular to a multifunctional frost heaving test system and a test method thereof.

Background

Soils and rocks that have a negative or zero temperature and contain ice are called frozen earth. When the water in the soil turns to ice, the volume increases by 9%, called frost heaving of the water in the soil, and when the volume expansion of the water in the soil is sufficient to cause relative displacement between soil particles, the volume expansion of the frozen soil is formed, called frost heaving of the soil. The frost heaving is divided into in-situ frost heaving and segregation frost heaving. In closed systems, in situ frost heaving occurs primarily in the soil. In an open system with water supply, water is moved to a certain position to be frozen under the action of a driving mechanism, namely segregation frost heaving, and the frost heaving amount is large. When salinization occurs in frozen soil, the complex soil-water-salt interaction changes the original frost heaving and water migration mechanism, and aggravates the damage of buildings under the condition of periodic temperature change.

At present, the research on soil water-heat-salt-force is mainly focused on the aspect of indoor model tests, when a single soil layer is researched, the temperature uniformity of a columnar soil sample needs to be maintained from top to bottom, when multiple soil layers are researched, the environment with temperature gradient change from top to bottom is provided, when the influence of underground water is simulated, the soil sample needs to be subjected to non-pressure water supplement, besides, the influence of different constraint conditions on frozen soil needs to be simulated, the test device in the prior art is low in integration level, and the coupling tests under the multiple conditions cannot be performed.

Disclosure of Invention

The invention aims to provide a multifunctional frost heaving test system aiming at the defect that a frost heaving test device in the prior art cannot meet the research requirements in multiple aspects.

The invention also aims to provide a test method of the multifunctional frost heaving test system.

The technical scheme adopted for realizing the purpose of the invention is as follows:

the utility model provides a multi-functional frost heaving test system, includes the support frame, set up in the experimental staving that is used for depositing the soil sample on the support frame, control the temperature control system of soil sample temperature, through experimental staving top, alternative are given the application of force system that constant pressure or infinite rigidity were applyed to the soil sample, through non-pressure water charging system and the detecting system of moisturizing in experimental staving lower part to the soil sample, wherein:

the test barrel body comprises an inner sample barrel for storing a soil sample and a cooling part arranged on the circumferential outer wall of the inner sample barrel;

the temperature control system comprises the cooling part, a lower cold plate fixed at the bottom of the test barrel body and an upper temperature control plate which can be matched into the inner sample barrel and is hermetically connected with the inner wall of the inner sample barrel, the upper temperature control plate applies load to the soil sample under the action of the force application system, and the bottom of the inner sample barrel is hermetically connected with the top of the lower cold plate;

the force application system comprises a lever force application device, a power-assisted rod and an upper counter-force beam, wherein the power-assisted rod is provided with a detachable force measuring ring, when the upper counter-force beam is fixedly connected with the support frame and the force measuring ring is not arranged on the power-assisted rod, the upper counter-force beam simulates an infinite rigidity condition by fixing the position of the upper temperature control plate, and when the upper counter-force beam is fixedly connected with the support frame and the force measuring ring is arranged on the power-assisted rod, a flexible boundary condition is simulated;

the non-pressure water supplementing system comprises a water supplementing cavity arranged at the bottom of the test barrel body and a communicating vessel structure for supplying water to the water supplementing cavity, and a water supplementing hole facing the soil sample is formed in the water supplementing cavity;

the detection system comprises a displacement sensor arranged on the force measuring ring and/or a stress sensor arranged on the force measuring ring and/or a temperature sensor used for measuring the temperature of the soil sample and/or a displacement sensor probe used for measuring the displacement of the soil sample in the vertical direction and/or a water supplementing metering device used for measuring the water supplementing quantity and the water supplementing rate.

In the above technical solution, the support frame includes a lower base plate and a guide bar fixed on the lower base plate, the bottom of the lower base plate is fixed with support legs, the lower cooling plate is fixed on the lower base plate, the upper reaction beam is slidably connected with the upper portion of the guide bar, and the upper reaction beam can be fastened on the guide bar through a fastening connector.

In the technical scheme, the insulation sleeve is arranged on the outer side of the test barrel body, the bottom of the insulation sleeve is fixed on the lower cold plate or the support frame, the top of the test barrel body is provided with the upper top plate capable of sealing the opening of the insulation sleeve, the upper top plate is fixed on the lower cold plate or the support frame through the first pull rod, the upper top plate is provided with the through hole for the assistant rod to penetrate out, and the assistant rod is connected with the through hole in a sealing mode.

In the technical scheme, the lever force application device comprises a lever assembly, a stress plate and a fulcrum block fixed at the bottom of the support frame, wherein the lever assembly comprises a lever and a weight capable of being selectively assembled at one end of the lever, the middle part of the lever is hinged on the stress plate, the stress plate is in sliding connection with a guide rod positioned below the support frame, a bottom fulcrum of the fulcrum block is in contact with the lever, and the stress plate is fixed on the upper counter-force beam through a second pull rod.

In the technical scheme, the other end of the lever is provided with a balance weight which can be adjusted along the length direction of the lever, and the balance weight are respectively positioned at two ends of the lever.

In the technical scheme, a displacement sensor probe is downwards fixed on the upper top plate, a measuring block is fixed on the boosting rod, and the displacement of the soil sample is measured by detecting the distance between the displacement sensor probe and the measuring block;

the temperature sensors comprise a first temperature sensor which penetrates through the upper temperature control plate and is vertically inserted into the soil sample and/or one or more second temperature sensors which penetrate through the side wall of the test barrel body and are horizontally inserted into the soil sample;

in the above technical scheme, the experimental staving includes first experimental staving and the double-deck staving of second of interchangeable, wherein first experimental staving include interior sample bucket and set up in the cooling portion on the outer wall of interior sample bucket circumference, the double-deck staving of second includes interior sample bucket and outer sample bucket, the bottom and the lower cold plate sealing connection of interior sample bucket, outer sample bucket slide cup joint in outside the interior sample bucket, form on the lateral wall of outer sample bucket and supply second temperature sensor male aperture, form the confession on the lateral wall of interior sample bucket the bar hole that second temperature sensor penetrated, the length in bar hole is greater than the aperture of aperture.

In the above technical scheme, the detection system further comprises a plurality of salinity sensors for testing salinity, the salinity sensors are inserted into the second double-layered barrel body at different heights, and reinforcing ribs are fixed on the side wall of the inner sample barrel of the second double-layered barrel body.

In the above technical scheme, the top of the power-assisted rod is fixed at the bottom of the upper counter-force beam, the bottom of the power-assisted rod is fixed with a force application disc, and the force application disc is coaxially fixed on the top surface of the upper temperature control plate.

In the above technical solution, the assisting rod comprises a positioning sleeve fixed at the bottom of the upper reaction beam, a stressed shaft fixedly sleeved in the positioning sleeve, and an upper temperature control plate reaction rod fixed at the top of the upper temperature control plate, wherein a groove is formed at the top of the upper temperature control plate reaction rod, the stress sensor is fixed in the groove, and the stressed shaft can be inserted into the groove in a matching manner to directly or indirectly act on the stress sensor;

the top of the force measuring ring is provided with a bulge which can be inserted into the positioning sleeve in a matching way, and the bottom of the force measuring ring is fixed with a fixed block which is inserted into the groove in a matching way and directly or indirectly acts on the stress sensor.

In the above technical solution, the cooling part is a cooling jacket or a cooling coil pipe arranged outside the inner sample barrel;

the upper temperature control plate and the lower cold plate comprise a cavity for storing cooling liquid, and a cold plate circulating liquid inlet pipe and a cold plate circulating liquid outlet pipe which are communicated with the cavity; or the upper temperature control plate and the lower cooling plate comprise an upper cooling plate and a lower cooling plate which are arranged from top to bottom, a spiral groove is formed in the lower cooling plate, the upper cooling plate covers the lower cooling plate, the spiral groove is sealed to form a spiral cooling liquid channel, and two ends of the spiral cooling liquid channel are respectively communicated with a cooling plate circulating liquid outlet pipe and a cooling plate circulating liquid inlet pipe.

In the above technical scheme, a sealing ring is arranged on the circumferential side wall of the upper temperature control plate.

In the technical scheme, the water replenishing plate and the lower cooling plate are enclosed to form a water replenishing cavity, two water inlets are arranged on the water replenishing cavity, one water inlet is connected with the Mariotte bottle through a water replenishing pipe, and the other water inlet is connected with a communicating hose to form a communicating vessel structure with the Mariotte bottle;

the water replenishing metering device comprises a weighing device arranged below the Mariotte bottle and a differential pressure gauge assembled on the water replenishing pipe.

In the above technical scheme, the moisturizing board with set up in annular flange on the cold drawing down forms the moisturizing cavity, the moisturizing board includes that the bottom permeates water the frame and is fixed in the orifice plate at the frame top is permeated water to the bottom, wherein the frame is permeated water to the bottom includes the rib that the net was alternately arranged, be equipped with the limbers that run through on the rib.

In another aspect of the invention, the testing method of the testing device is that the soil sample is loaded into the inner sample barrel, the upper temperature control plate and the lower cold plate seal the upper end and the lower end of the testing barrel body, so that the soil sample is in a relative sealing state, and the following three aspects of coupling tests can be carried out:

(1) single soil layer or temperature gradient: when the cooling part is closed and the lower cooling plate and the upper temperature control plate are opened, a temperature gradient is formed in the soil sample to simulate a plurality of soil layer tests, and when the lower cooling plate and the upper temperature control plate are closed and the cooling part is opened, the temperature in the soil sample is fixed uniformly to simulate a single soil layer test;

(2) open or closed systems: when the non-pressure water replenishing system is started, an open system test is carried out to simulate groundwater replenishment, the lower cooling plate and the upper temperature control plate are started while the non-pressure water replenishing is carried out, the temperature gradient is used as a water replenishing driving force, and when the non-pressure water replenishing system is closed, a closed system test is carried out to simulate the non-groundwater replenishment;

(3) constant stress or infinite stiffness or flexibility boundary conditions: when the upper reaction beam is fixedly connected with the support frame and the force measuring ring 60 is not arranged on the boosting rod 54, the displacement of the soil sample is completely limited, and a test under the condition of infinite rigidity is carried out;

when the upper counter-force beam is movably connected with the support frame, the upper counter-force beam is pulled down by the constant tension of the lever force application device to perform a test under the constant stress condition;

when the upper reaction beam 2 is fixedly connected with the support frame and the force measuring ring is arranged on the assistance rod, a test under a flexible boundary condition is carried out, the expansion force change mechanism of the soil sample is researched, and theoretically, the expansion force is increased along with the increase of displacement.

In the test process, the displacement sensor is arranged on the vertical diameter of the measuring ring structure through the connecting part, the vertical deformation displacement of the ring structure can be detected, the temperature sensor collects the temperature change of the soil sample in real time, the stress sensor can reflect the stress generated by the soil sample in the frost heaving process, the displacement sensor probe measures the displacement of the soil sample in the vertical direction in the freeze thawing process, and the water replenishing measuring device measures the water replenishing amount and the water replenishing rate.

In the technical scheme, when a single soil layer test is carried out, the test barrel body adopts a first test barrel body, and the temperature sensor adopts a first temperature sensor which is inserted into the soil sample from the upper temperature control plate;

when the temperature gradient test is carried out, the test barrel body adopts a second double-layer barrel body, and the temperature sensors adopt a plurality of second temperature sensors inserted into the soil sample from the side wall of the second double-layer barrel body.

Compared with the prior art, the invention has the beneficial effects that:

1. the invention provides a test device which can not only carry out temperature gradient (the temperature of a soil layer is changed in a gradient manner from top to bottom), but also can carry out research on a single soil layer (the temperature of each position in the soil layer is consistent), can carry out test research on a constant stress condition (a force measuring ring is not installed, an upper reaction beam is pulled down by a lever device), an infinite rigidity condition (a force measuring ring is not installed, an upper reaction beam is locked) or a boundary condition (a force measuring ring is installed, an upper reaction beam is locked), can carry out an open system test (a non-pressure water replenishing system is started, underground water replenishing in an actual stratum is simulated), and can carry out a closed system test (a non-pressure water replenishing system is closed, and no underground water replenishing is simulated in the actual stratum). Thus, various experimental studies are carried out, and the functions are diversified. In addition, the testing device disclosed by the invention is simple in structure, convenient to disassemble and assemble, simple and convenient to operate and convenient to popularize and apply.

2. The invention adopts the lever force application device, can effectively apply constant load to the soil sample, and can apply larger load to the soil sample through the weight with smaller weight by fully utilizing the lever principle through the lever structure so as to meet the requirements of different test conditions. Meanwhile, the displacement of the sample can be completely limited, and the limiting conditions can be switched. Thereby satisfying the function in the multi-application scene.

3. By utilizing the structure of the replaceable double-layer barrel body, the lateral limitation of the transversely arranged temperature sensor (or other sensors such as a salinity sensor) on the expansion process of the soil sample is effectively avoided, the expansion of the soil sample is blocked (the locking is prevented), and the test measurement precision of the device is improved.

Drawings

FIG. 1 is a front view of the test apparatus.

FIG. 2 is a front view of the test apparatus.

FIG. 3 is a side view of the test apparatus.

FIG. 4 is a connection relationship diagram of the test barrel body, the water source, the upper temperature control plate, the lower cooling plate, the upper top plate and the lower bottom plate.

Figure 5 is an enlarged view of a portion of figure 1 (the position of the upper permeate plate for ease of illustration).

Fig. 6 is a schematic structural view of the permeable plate.

Fig. 7 is a schematic view of the structure of the cooling jacket and the inner sample barrel.

Fig. 8 is a schematic view of the structure of the cooling coil and the inner sample barrel.

Fig. 9 is a schematic structural view of an upper temperature control plate.

Fig. 10 is a structural view of the second double-layered tub body.

FIG. 11 is a schematic view showing an assembly structure of a force measuring ring (omitting a lever force applying means, a non-pressure water charging system, etc.)

In the figure: 1-an inner sample barrel, 2-an upper counter-force beam, 3-an upper temperature control plate, 4-an annular flange, 5-a water replenishing pipe, 6-a stress sensor, 7-a displacement sensor probe, 8-a force application disc, 9-a reinforcing wing, 10-an upper top plate, 11-a lower bottom plate, 12-a first pull rod, 13-a bolt, 14-a supporting leg, 15-a measuring block, 16-a first temperature sensor, 17-a second temperature sensor, 18-a small hole, 19-a strip-shaped hole, 20-a positioning sleeve, 21-a stress shaft, 22-an upper temperature control plate counter-force rod, 23-an assembly groove, 24-a guide rod, 25-a cooling jacket, 26-a cooling coil, 27-a cavity circulating liquid outlet and 28-a cavity circulating liquid inlet, 29-circulating liquid inlet, 30-circulating liquid outlet, 31-cavity, 33-cold plate circulating liquid inlet pipe, 34-upper cooling plate, 35-lower cooling plate, 36-spiral groove, 37-cold plate circulating liquid outlet pipe, 38-cold plate circulating liquid inlet pipe, 39-water permeable frame, 40-pore plate, 41-water through hole, 42-stress plate, 43-fulcrum block, 44-lever, 45-balance block, 46-weight, 47-second pull rod, 48-tray, 49-connecting rod, 50-outer sample barrel, 51-March's bottle, 52-differential pressure gauge, 53-connecting plate, 54-power-assisting rod, 55-groove, 56-temperature sensor hole, 57-hose, 58-heat-insulating sleeve and 59-sealing ring, 60-measuring ring, 61-displacement sensor.

Detailed Description

The invention is described in further detail below with reference to the figures and specific examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The utility model provides a multi-functional frost heaving test system includes the support frame, set up in experimental staving, control on the support frame the temperature control system of soil sample temperature, pass through experimental staving top alternative is given the force application system of different loads is applyed to the soil sample, is passed through non-pressure water charging system and the detecting system of water supply in experimental staving lower part to the soil sample, wherein:

the test barrel body comprises an inner sample barrel 1 for storing a soil sample and a cooling part arranged on the circumferential outer wall of the inner sample barrel 1;

the temperature control system comprises the cooling part, a lower cooling plate fixed at the bottom of the test barrel body and an upper temperature control plate 3 which can be matched and connected with the inner wall of the inner sample barrel 1 in a sealing way, the upper temperature control plate 3 applies load to the soil sample under the action of the force application system, and the bottom of the inner sample barrel is connected with the top of the lower cooling plate in a sealing way (an assembly groove 23 for inserting the bottom of the test barrel body is formed at the top of the lower cooling plate, so that the test barrel body is positioned and the inner sample barrel 1 is sealed conveniently);

the force application system comprises a lever force application device, a boosting rod 54 and an upper reaction beam 2, wherein the boosting rod 54 is provided with a detachable force measuring ring 60, when the upper reaction beam 2 is fixedly connected with the support frame and the force measuring ring 60 is not arranged on the boosting rod 54, the upper reaction beam 2 simulates an infinite rigidity condition by fixing the position of the upper temperature control plate 3, when the upper reaction beam 2 is fixedly connected with the support frame and the force measuring ring 60 is arranged on the boosting rod 54, a flexible boundary condition is simulated, and when the upper reaction beam 22 is movably connected with the support frame, the upper reaction beam 2 pulled down by the lever force application device applies a load to the upper temperature control plate 3 through the boosting rod 54 to simulate a constant stress condition;

the non-pressure water supplementing system comprises a water supplementing plate arranged at the bottom of the test barrel body, the water supplementing plate and a lower cold plate are enclosed to form a water supplementing cavity, and the water supplementing cavity supplies water through a communicating vessel structure. Different with the peristaltic pump supplies water through pressure, non-pressure moisturizing is chooseed for use in this application to simulate actual stratum environmental conditions. After the upper temperature control plate 3 and the lower cold plate are opened, the soil sample forms a temperature gradient, and non-pressure water supplement is carried out through the communicating vessel structure under the driving force action of the temperature gradient.

The detection system comprises a displacement sensor 61 arranged on the force measuring ring 60 and/or a stress sensor 6 arranged on the power assisting rod 54 and/or a temperature sensor for measuring the temperature of the soil sample and/or a displacement sensor probe 7 for measuring the displacement of the soil sample in the vertical direction and/or a water supplementing metering device for measuring the water supplementing quantity and the water supplementing rate.

In the interior sample bucket 1 of packing into with the soil sample, go up the upper and lower both ends of accuse temperature board 3 and lower cold plate seal test staving for the soil sample is in relative sealed state, can carry out the coupling test of following three aspects:

(1) single soil layer or temperature gradient: when the cooling part is closed and the lower cooling plate and the upper temperature control plate 3 are opened, a temperature gradient is formed in the soil sample to simulate a plurality of soil layer tests, and when the lower cooling plate and the upper temperature control plate 3 are closed and the cooling part is opened, the temperature in the soil sample is fixed uniformly to simulate a single soil layer test;

(2) open or closed systems: when the non-pressure water charging system is started, performing an open system test to simulate groundwater recharge, and when the non-pressure water charging system is closed, performing a closed system test to simulate non-groundwater recharge; the communicating vessel structure formed by the components of the Mariotte bottle can simulate non-pressure water supplement in an actual stratum during testing.

(3) Constant stress or infinite stiffness or flexibility boundary conditions:

when the upper reaction beam 2 is fixedly connected with the support frame and the force measuring ring 60 is not arranged on the boosting rod 54, a test under the condition of infinite rigidity is carried out, at the moment, the displacement of the soil sample is completely limited, the expansion force change mechanism of the soil sample is researched, and theoretically, the expansion force is increased along with the increase of the displacement;

when the upper reaction beam 2 is movably connected with the support frame and the force-measuring ring 60 is not arranged on the booster rod 54, the upper reaction beam 2 is pulled down by the constant tension of the lever force-applying device to perform a test under the condition of constant stress, at the moment, a soil sample is equivalent to a heavy object with fixed weight, the pressure is unchanged, and the expansion force is theoretically fixed and is equivalent to the stress generated by overlying load;

when the upper reaction beam 2 is fixedly connected with the support frame and the force measuring ring 60 is installed on the boosting rod 54, the test under the flexible boundary condition is carried out, and the pressure above the soil sample is gradually increased along with the expansion process.

In the test process, the displacement sensor 61 is arranged on the vertical diameter of the ring structure of the force measuring ring 60 through a connecting part, and can detect the vertical deformation displacement of the ring structure; in practice, the displacement measured by the force ring 60 can be compared and verified with the displacement measured by the displacement sensor probe 7 to make reference to the determination of the accuracy of the test results.

The temperature sensor collects the temperature change of the soil sample in real time, the stress sensor 6 can reflect the stress generated by the soil sample in the frost heaving process, the displacement sensor probe 7 measures the displacement of the soil sample in the vertical direction in the freeze thawing process, the water supplementing measuring device measures the water supplementing amount and the water supplementing speed, and the data can be manually recorded and processed and can also be transmitted to the monitoring terminal for automatic processing.

The support frame comprises a lower base plate 11 and a guide rod 24 fixed on the lower base plate 11, the lower cold plate is fixed on the lower base plate 11, and the bottom of the inner sample barrel 1 is hermetically fixed on the upper surface of the lower cold plate. The upper reaction beam 2 is slidably connected with the upper part of the guide rod 24, the upper reaction beam 2 can be fastened on the guide rod 24 through a fastening connecting piece, and the stress plate 42 is slidably connected with the guide rod 24 positioned below the support frame to play a role in guiding, so that the stress plate 42 is ensured to move up and down in the vertical direction.

When the guide bar 24 is fastened to the upper reaction beam 2 by means of the fastening connection, tests can be performed under infinite stiffness conditions, in which mainly the stress state, i.e. the state of frost heave force, is measured. The fastening connecting piece can select fixing bolt for use, sets up the screw thread on the guide bar 24, utilizes fixing bolt to fix the both ends of upper portion counter-force roof beam 2 respectively on two guide bars 24, and the position of upper portion counter-force roof beam 2 is fixed.

The guide rod 24 is arranged to enable force to be transmitted in a vertical direction without deviation, the vertical guide rod 24 is fixed on the support frame, more preferably, the bottom of the guide rod 24 penetrates through the lower base plate 11 and is fixed on the lower base plate 11 through a connecting bolt, and a guide hole for the guide rod 24 to penetrate is formed at the end part of the upper reaction force beam 2. Furthermore, the two guide rods 24 are symmetrically arranged on the left side and the right side of the test barrel body, and two ends of the upper reaction beam 2 are respectively connected with the two guide rods 24 in a sliding manner.

In order to maintain the stability of the temperature in the experimental barrel body, the outer side of the experimental barrel body is provided with the heat preservation sleeve 58, the bottom of the heat preservation sleeve 58 is fixed on the lower cold plate or the lower cold plate 11, the top of the experimental barrel body is provided with the upper top plate 10 capable of sealing the opening of the experimental barrel body, the upper top plate 10 is fixed on the lower bottom plate 11 or the lower cold plate through the first pull rod 12, a through hole for the assistant rod 54 to penetrate out is formed in the upper top plate 10, the assistant rod 54 is connected with the through hole in a sealing manner, the heat insulation effect can be achieved, the heat loss is reduced, and the upper top plate 10 and the outermost heat preservation sleeve 58 form a closed space to. The bottom of the first pull rod 12 is fixed on the lower bottom plate 11 or the lower cold plate through a bolt 13, and the upper top plate 10 is fastened on the top of the first pull rod 12 through a bolt 13; the upper end and the lower end of the first pull rod 12 are both threaded sections, the upper top plate 10 and the lower bottom plate 11 can be fixed through bolts 13 in threaded connection with the first pull rod, as shown in the figure, the three first pull rods 12 are arranged, the axial centers of the test barrel bodies are used as axes and are uniformly distributed in an annular array, and supporting legs 14 are fixed to the bottom of the lower bottom plate 11, so that the whole test device is placed on a test platform.

When the upper and lower cold plates or the surrounding cooling parts are opened, the sample has no heat loss in the vertical direction, so that the test is more accurate and is close to the real natural condition.

As shown in fig. 2-3, the lever force applying device includes a lever assembly, a force-bearing plate 42, and a fulcrum block 43 fixed at the bottom of the supporting frame, wherein the lever assembly includes a lever 44 and a weight 46 selectively assembled at one end of the lever 44, the middle portion of the lever 44 is hinged on the force-bearing plate 42, the bottom fulcrum of the fulcrum block 43 is in contact with the lever 44, and the force-bearing plate 42 is fixed on the upper reaction beam 2 through a second pull rod 47. The second pull rod 47 is provided with two symmetrical pull rods, so that symmetrical pull force is formed. A contact groove is formed at a position where the lever 44 contacts the bottom fulcrum. In order to adapt to the earth columns with different heights, the fulcrum blocks 43 are a plurality of replaceable fulcrum blocks 43 with different heights, or the fulcrum blocks 43 with adjustable heights are used for adjusting the distance between the lever 44 and the lower base plate 11 when the lever is balanced.

When weights 46 with different numbers or weights are assembled at the end parts of the levers 44, the levers 44 provide constant tension for the stress plate 42, and then the second pull rods 47 provide constant tension for the upper reaction beam 2, so that the constant load can be verified. In the same manner as the first tie bar 12, the top of the second tie bar 47 is fastened to the upper reaction beam 2 by fastening bolts, the bottom is fastened to the force-receiving plate 42 by fastening bolts, and the fastening bolts are removed when the upper reaction beam 2 is removed.

Further, in order to keep the balance of the lever 44, the other end of the lever 44 is provided with a weight 45 adjustable along the length direction thereof, and the weight 45 and the weight 46 are respectively located at both ends of the lever 44. One section of the lever 44 is a threaded rod, and the balance weight 45 is connected with the threaded rod through threads. Before the weights are placed, the balance weight 45 is adjusted to balance the whole lever system, and then the weights 46 are added.

Further, a tray 48 for placing a weight 46 is fixed to an end of the lever 44. The tray 48 is fixed on the end of the lever 44 through a connecting rod 49, the top of the connecting rod 49 is fixedly connected on the lever 44 through a connecting screw rod hinge or an integral forming mode, the lever 44 is directly hinged on the stress plate 42 through a connecting shaft or a connecting screw rod, the position on the lever 44 close to the middle part is contacted with the fulcrum block 43, and the end of the lever 44 is hinged on two opposite connecting plates 53 on the top of the stress plate 42 through a connecting shaft.

For accurate collection displacement data, displacement sensor probe 7 is fixed in down on the roof 10, be fixed with a measuring block 15 on the helping hand pole 54, displacement sensor probe 7 survey with the displacement of the interval measurement soil sample between the measuring block 15. For example, when the soil sample is frozen and swelled, the soil sample moves upward in the vertical direction, and the displacement between the displacement sensor probe 7 and the measuring block 15 is reduced, thereby measuring the displacement of the soil sample.

In order to accurately measure the temperature in the soil sample, the temperature sensor comprises a first temperature sensor 16 vertically inserted into the soil sample through the upper temperature control plate 3 and/or one or more second temperature sensors 17 horizontally inserted into the soil sample through the side wall of the test barrel body. When the second temperature sensor 17 is provided with a plurality of temperature sensors, the temperature of the soil sample at different height positions can be detected, the frost heaving test of the soil layer(s) under the temperature gradient is carried out, the temperature to be measured is the temperature distribution on the whole soil column, and the temperature is different because of the temperature gradient on the whole soil column, so the temperature sensors are inserted on the side walls.

The second temperature sensor inserts from sample bucket lateral wall trompil, and when the soil body inflation, a plurality of second temperature sensors and experimental staving exert the side direction restriction to the soil sample, can form "locking" structure, cause great restriction to the soil body inflation, have reduced the measurement accuracy of salt-frost heaving appearance.

In order to prevent the soil sample from being laterally limited during the frost heaving process, namely being locked by a test barrel body, the test barrel body comprises a first test barrel body and a second double-layer barrel body which can be replaced, wherein the first test barrel body comprises the inner sample barrel 1 and a cooling part arranged on the circumferential outer wall of the inner sample barrel 1, as shown in fig. 7-8, the second double-layered bucket body includes an inner sample bucket 1 and an outer sample bucket 50, as shown in fig. 10, the bottom of the inner sample barrel 1 is hermetically connected with the lower cold plate, the inner sample barrel 1 is slidably sleeved in the outer sample barrel, a small hole 18 into which the second temperature sensor 17 is inserted is formed on the side wall of the outer sample barrel, form the confession on the lateral wall of interior sample bucket 1 the strip hole 19 that second temperature sensor 17 penetrated, the aperture in strip hole 19 is greater than the aperture of aperture 18. The bar hole with the aperture one-to-one sets up, bar hole 19 provides the space that reciprocates for second temperature sensor 17, so soil sample is at the frost heaving in-process, drives second temperature sensor 17 and shifts up, and outer sample bucket 50 and second temperature sensor 17 shift up 1 in relatively, prevent that soil sample from being locked by experimental staving, improve the precision of test.

In order to test the influence of salinity, the detection system further comprises a plurality of salinity sensors for testing salinity, and the salinity sensors are inserted into different heights of the double-layer barrel body. In the same manner as the second temperature sensor 17.

In order to prevent the cracking of the inner sample barrel 1 caused by the overlarge overlying load during the overlying load test, reinforcing ribs are fixed on the side wall of the inner sample barrel 1.

Therefore, when a single soil layer test is carried out, the first test barrel body is assembled on the support frame, and when a gradient temperature test is carried out, the second double-layer barrel body is assembled on the support frame. Different test barrel bodies are selected according to different test requirements.

In order to visually check the change of the soil sample in the frost heaving process, the test barrel body is made of transparent materials.

In order to enable the assisting rod 54 to uniformly apply a load to the upper temperature control plate 3, the top of the assisting rod 54 is fixed to the bottom of the upper reaction beam 2, the bottom of the assisting rod is fixed with a force application disc 8, the force application disc 8 is coaxially fixed to the top surface of the upper temperature control plate 3, further, reinforcing wings 9 are fixed between the bottom of the assisting rod 54 and the force application disc 8, the reinforcing wings 9 are distributed in an annular array mode with the axis of the assisting rod 54, as shown in the figure, the number of the reinforcing wings 9 is three, and the angle between every two adjacent reinforcing wings 9 is 120 degrees.

In order to accurately acquire data by the stress sensor 6, the assisting rod 54 comprises a positioning sleeve 20 fixed at the bottom of the upper reaction beam 2, a stress shaft 21 penetrating and sleeved in the positioning sleeve 20, and an upper temperature control plate reaction rod 22 fixed at the top of the upper temperature control plate 3, wherein a groove 55 is formed at the top of the upper temperature control plate reaction rod 22, the stress sensor 6 is fixed in the groove 55, and the stress shaft 21 can be inserted into the groove 55 in a matching manner to directly or indirectly act on the stress sensor 6;

the top of the force measuring ring 60 is provided with a protrusion which can be inserted into the positioning sleeve 20 in a matching manner, and the bottom of the force measuring ring 60 is fixed with a fixed block which is inserted into the groove 55 in a matching manner and directly or indirectly acts on the stress sensor 6. So set up convenient to detach assembly, and can improve measuring precision. When the force measuring ring 60 is installed, the protrusion at the top of the force measuring ring 60 is inserted into the positioning sleeve 20, and the fixing block at the bottom of the force measuring ring 60 is inserted into the groove 55. When the force measuring ring 60 is not installed, the top of the force bearing shaft 21 is inserted into the positioning sleeve 20, and the bottom of the force bearing shaft 21 is inserted into the groove 55.

The cooling part is a cooling jacket 25 or a cooling coil 26 arranged outside the inner sample barrel 1. When the cooling part is a cooling jacket 25, a temperature control cavity for storing cooling liquid is formed in the cooling jacket 25, a cavity circulating liquid outlet 27 communicated with the temperature control cavity is formed in the top of the cooling jacket 25, and a cavity circulating liquid inlet 28 communicated with the temperature control cavity is formed in the bottom of the cooling jacket 25. When the cooling part is a cooling coil 26, the cooling coil 26 is spirally wound on the outer wall of the test barrel body, the bottom of the cooling coil 26 is a circulating liquid inlet 29, and the top of the cooling coil 26 is a circulating liquid outlet 30.

Go up accuse temperature board 3 and cold board down all can adopt following two kinds of structures:

first, the upper temperature control plate 3 and the lower cold plate include a cavity 31 for storing cooling fluid, and a cold plate circulation fluid inlet pipe 32 and a cold plate circulation fluid outlet pipe 33 which are communicated with the cavity 31. The temperature of the upper temperature control plate 3 is controlled by circulating cooling liquid. When the upper temperature control plate 3 is provided with the force application disc 8, the circulating liquid inlet pipe of the upper temperature control plate and the circulating liquid outlet pipe of the upper temperature control plate penetrate out of the force application disc 8.

And the second method comprises the following steps: the upper temperature control plate 3 and the lower cooling plate both comprise an upper cooling plate 34 and a lower cooling plate 35 which are arranged from top to bottom, a spiral groove 36 is arranged in the lower cooling plate 35, when the upper cooling plate 34 covers the lower cooling plate 35, the spiral groove 36 is sealed to form a spiral cooling liquid channel, and two ends of the spiral cooling liquid channel are respectively communicated with a cold plate circulating liquid outlet pipe 37 and a cold plate circulating liquid inlet pipe 38. The upper cooling plate 34 and the lower cooling plate 35 can be fastened and connected through screws, and the cooling effect can be optimized through the arrangement mode of the spiral cooling liquid channel. The annular flange 4 is formed on the top of the upper cooling plate 34 of the lower cooling plate for easy machining, and the upper cooling plate 34 and the lower cooling plate 35 of the upper temperature control plate 3 can be provided with temperature sensor holes 56 for inserting the first temperature sensors 16.

In order to ensure the tightness between the upper temperature control plate 3 and the inner wall of the inner sample barrel 1, a sealing ring 59 is arranged on the circumferential side wall of the upper temperature control plate 3.

Furthermore, two water inlets are arranged on the water supplementing cavity, one water inlet is connected with the March's flask 51 through a water supplementing pipe 5, the other water inlet is connected with a communication hose 57 to form a communicator structure with the March's flask 51, and the water supplementing metering device comprises a weighing device arranged below the March's flask 51 and a differential pressure gauge 52 assembled on the water supplementing pipe;

the weighing device can adopt electronic balance, measures the moisturizing volume among the test process, but camera shooting or the change of manual observation Markov's bottle middle scale in order to calculate the moisturizing volume, set up differential pressure gauge 52 on moisturizing pipe 5 and measure the moisturizing rate, the height that the port of intercommunication hose 57 hose was placed is equivalent with differential pressure gauge 52 height, so forms a linker structure, realizes the non-pressure moisturizing. And a connecting pipe is respectively fixed on the two water inlets, extends out through a through hole on the lower cold plate to be respectively connected with a water supplementing pipe 5 and a communicating hose 57, and the water supplementing pipe 5 and the communicating hose 57 are in sealing connection with the through hole).

The water replenishing plate and the annular flange 4 arranged on the lower cooling plate form a water replenishing cavity, the water replenishing plate comprises a bottom water permeable frame 39 and a pore plate 40 fixed at the top of the bottom water permeable frame 39, the bottom water permeable frame 39 comprises ribs which are arranged in a grid crossed mode, and through water holes 41 are formed in the ribs.

Water supplied by the water replenishing pipe 5 enters the water replenishing plate, is uniformly distributed in the bottom water permeable frame 39 through the water through holes 41 and then enters the soil sample through the small holes 18 in the pore plate 40, so that uniform water replenishing for the soil sample is ensured, the influence on a test result caused by nonuniform water distribution in the soil sample is prevented, and the reliability of the test result is further improved.

Example 2

And (3) performing frost heaving test on a single soil layer under the condition of a closed system (a non-pressure water replenishing system is closed), under the condition of constant stress or infinite rigidity or under the condition of a flexible boundary.

Filling a soil sample:

(1) if the guide rod 24 is provided with the adjusting bolt, the adjusting bolt is firstly screwed off, so that the upper reaction beam 2 is in sliding connection with the guide rod 24, the fastening bolt between the upper reaction beam 2 and the second pull rod 47 is taken down, and the upper reaction beam 2 is taken down;

(2) the bolt 13 is unscrewed, and the upper top plate 10 is taken down;

(3) taking the upper temperature control plate out of the test barrel body, and filling a soil sample through the top opening of the test barrel body;

(4) the upper temperature control plate is pressed and installed right above the soil sample, the top plate 10 is covered, the bolt 13 is screwed, the upper counter-force beam 2 is installed, and two ends of the upper counter-force beam 2 are fastened on the second pull rod 47 by utilizing the fastening bolt;

(5) the position of the upper reaction beam 2 is fixed by means of adjusting bolts as necessary.

After filling soil samples, the frost heaving test of a single soil layer under the condition of constant stress in example 2.1 and the frost heaving test of a single soil layer under the condition of infinite rigidity in example 2.2 are respectively carried out, each of examples 2.1 and 2.2 comprises single freezing and freezing-thawing circulation, the freezing and thawing circulation is related to the temperature condition, the first test barrel body shown in figure 7 or figure 8 is adopted as the test barrel body in the example, and the first temperature sensor is used for temperature measurement.

2.1

According to the above steps, the soil sample is loaded, the force measuring ring 60 is not installed, the adjusting bolt is not installed, the upper reaction beam 2 is connected with the guide rod 24 in a sliding manner, the rated number of weights 46 are placed on the tray 48, the lever 44 rotates with the fulcrum block 43 as a fulcrum, the upper reaction beam 2 is pulled down through the second pull rod 47, the upper reaction beam 2 applies a load to the upper temperature control plate 3 through the assisting rod 54, and the upper temperature control plate 3 applies a constant load to the soil sample.

2.1.1

The frost heaving test of the constant-stress single soil layer under single cooling is carried out, and the specific operation flow is as follows: the cooling part is connected with a cooling bath, the temperature of the cooling bath is adjusted to be 25-20-15-10-5-0-5-15-10-15-20, and the frost heaving test of a single soil layer under a single cooling is simulated. Such as the temperature change of a single soil layer from day to night, a frost heave test at a single cooling is performed.

2.1.2

And (5) performing a frost heaving test under the freeze-thaw cycle of the constant-stress single soil layer. The specific operation flow is as follows: the cooling part is connected with a cooling bath, the temperature of the cooling bath is adjusted to be 25-20-15-10-5-0 to (-5) DEG C to (-10) DEG C to (-15) DEG C to (-20) DEG C to (-15) DEG C to (-10) DEG C to (-5) DEG C to-0-5-10-15-20-25 ℃, and the macroscopic temperature change of the soil layer in all seasons is simulated.

2.2

After the soil sample is loaded, the upper reaction force beam 2 is fastened to the guide rod 24 by the adjusting bolt without installing the force measuring ring 60, thereby completely restricting the displacement of the sample. The rest test steps are referred to the operation flows in 2.1.1 and 2.1.2, and the frost heaving test under single cooling of the single soil layer with infinite rigidity and the frost heaving test under freeze-thaw cycle of the single soil layer with infinite rigidity can be respectively carried out.

2.3

After the soil sample is loaded, the force measuring ring 60 is attached, and the upper reaction force beam 2 is fastened to the guide bar 24 by the adjusting bolt. The rest test steps are referred to the operation flows in 2.1.1 and 2.1.2, and the frost heaving test under single cooling of the single soil layer and the frost heaving test under freeze-thaw cycle of the infinite-stiffness single soil layer under the condition of flexible boundary can be respectively carried out.

The measurement parameters in this example 2.1 and 2.2 are the amount of frost heave (measured by the displacement sensor probe 7), the frost heave stress (measured by the stress sensor 6) and the temperature change of the sample (measured by the first temperature sensor 16). In example 2.2, the frost heaving amount can only be used for measuring tiny thawing displacement (in the freezing and thawing cycle), and in example 2.3, the displacement sensor 61 is also used for measuring the vertical deformation displacement of the ring structure of the force measuring ring 60. Theoretically, the displacement deformation measured by the force measuring ring 60 and the displacement measured by the displacement sensor probe 7 should be the same. We can perform precision alignment. The displacement measured by the force ring 60 is multiplied by the stiffness coefficient K of the force ring, which is equal to the frost heave stress, F ═ K × Δ X. F should be consistent with that measured by the stress sensor 6.

Example 3

3.1

In the frost heaving test of the soil layer under the constant stress condition, the test device is adjusted in the same way as in example 2.1, and the process of filling the soil sample is in the same way as in example 2. The test barrel body of the embodiment adopts a second double-layer barrel body as shown in fig. 10, a plurality of second temperature sensors are inserted into the side wall, and the plurality of second temperature sensors can measure the temperature change of the soil sample in the vertical direction. In addition, the second double-layer barrel body can be inserted with a salinity sensor to measure salinity change of the soil column in the vertical direction.

3.1.1 open System Single Freeze test

The non-pressure water replenishing system is opened, the Ma bottle is connected to form a communicating vessel structure for non-pressure water replenishing, the circumferential cooling part is closed, the lower cold plate and the upper temperature control plate 3 are respectively connected with the cold bath, water is migrated in the soil layer under the action of temperature gradient to perform non-pressure water replenishing, the lower cold plate maintains constant temperature (generally negative temperature, in the embodiment, the temperature is minus 1 ℃), and the temperature of the upper temperature control plate 3 is changed according to the form of 25 ℃ -20 ℃ -15 ℃ -5 ℃ -0 ℃ -minus-5 ℃ -minus-10 ℃ -minus-15 ℃ -minus-20 ℃.

The data that need gather have moisturizing volume and moisturizing rate, the vertical ascending temperature gradient of soil sample (a plurality of second temperature sensor measurement), the frost heaving volume (through displacement sensor probe 7 measurement) and frost heaving stress (through the stress sensor measurement, theoretically with on load equal).

3.1.2 open System Freeze thaw cycle test

The non-pressure water replenishing process is the same as 3.1.1, the lower cold plate and the upper temperature control plate 3 are respectively connected with the cold bath, the lower cold plate maintains a constant temperature (generally a negative temperature, in this embodiment, the temperature is minus 1 ℃), and the temperature of the upper temperature control plate 3 is changed according to the form of 25 ℃ -20 ℃ -15 ℃ -5 ℃ -0 ℃ (-5 ℃ (-10) - (-15) ° c- (-20) - (-15) ° 15 ℃ -5 ℃ -0 ℃ -5 ℃ -10 ℃ -15 ℃ -20 ℃ (the temperature range is 5 ℃ in this embodiment, and the temperature range can be adjusted as required and can also be set to be changed by a sine function).

3.1.3 closed System Single Freeze test

The non-pressure water supply system is closed, the mahalanobis bottle is not connected, the temperature is controlled in the same way as in the embodiment 3.1.1, and the data to be collected comprise the temperature gradient in the vertical direction of the soil sample (measured by a plurality of second temperature sensors), the frost heaving amount (measured by a displacement sensor probe 7) and the frost heaving stress (measured by a stress sensor and theoretically equal to the overlying load).

3.1.4 closed System Freeze thaw cycle test

And (3) closing the non-pressure water supplementing system, not connecting the Mariotte bottle, controlling the temperature in the same way as in example 3.1.2, and collecting the data in the same way as in example 3.1.3.

3.2

In the frost heaving test of the soil layer under the temperature gradient under the infinite rigidity condition, the test device is adjusted in the same way as in example 2.2, and the process of filling the soil sample is in the same way as in example 2. The test barrel body of the embodiment adopts a second double-layer barrel body as shown in fig. 10, a plurality of second temperature sensors are inserted into the side wall, and the plurality of second temperature sensors can measure the temperature change of the soil sample in the vertical direction. In addition, the second double-layer barrel body can be inserted with a salinity sensor to measure salinity change of the soil column in the vertical direction. By adopting the test steps of the embodiments 3.1.1-3.1.4, the open system single freezing test, the open system freezing-thawing cycle test closed, the closed system single freezing test and the closed system freezing-thawing cycle test can be respectively carried out under the condition of infinite rigidity.

3.3

In the frost heaving test of the soil layer under the flexible boundary condition temperature gradient, the test device is adjusted in the same way as in example 2.3, and the process of filling the soil sample is in the same way as in example 2. The test barrel body of the embodiment adopts a second double-layer barrel body as shown in fig. 10, a plurality of second temperature sensors are inserted into the side wall, and the plurality of second temperature sensors can measure the temperature change of the soil sample in the vertical direction. The test procedures of examples 3.1.1-3.1.4 were used to perform the open system single freeze test, open system freeze-thaw cycle test closed, closed system single freeze test, and closed system freeze-thaw cycle test, respectively, of the flexible boundary conditions.

In summary, in addition to the above embodiments, the present device may select a condition in a single soil layer or a temperature gradient (multiple soil layer simulation); selecting a condition from an open system (opening the non-pressure water replenishing system) and a closed system (closing the non-pressure water replenishing system); and selecting one of the boundary conditions of constant stress, infinite rigidity and flexibility to carry out combined classification, and carrying out research under various conditions. In addition to this, the above test conditions can also be switched during the test. It is worth explaining that when a single soil layer test is carried out under the condition of an open system, the lower cold plate and the upper temperature control plate 3 are started firstly to form a temperature gradient, and then the non-pressure water supplementing system is opened, wherein the temperature gradient is the driving force for soil layer moisture migration. After water replenishing is completed, the lower cooling plate and the upper temperature control plate 3 are closed, the circumferential cooling part is opened, the temperature of the soil body is adjusted to be uniform, and a test is carried out.

Spatially relative terms, such as "upper," "lower," "left," "right," and the like, may be used in the embodiments for ease of description to describe one element or feature's relationship to another element or feature as illustrated in the figures. It will be understood that the spatial terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "below" other elements or features would then be oriented "above" the other elements or features. Thus, the exemplary term "lower" can encompass both an upper and a lower orientation. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

Moreover, relational terms such as "first" and "second," and the like, may be used solely to distinguish one element from another element having the same name, without necessarily requiring or implying any actual such relationship or order between such elements.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims

1. Multi-functional frost heaving test system, its characterized in that, including the support frame, set up in be used for depositing the experimental staving of soil sample on the support frame, control the temperature control system of soil sample temperature, through experimental staving top, alternative give the force application system that constant pressure or infinite rigidity were applyed to the soil sample, through experimental staving lower part is to non-pressure water charging system and the detecting system of moisturizing in the soil sample, wherein:

the detection system comprises a displacement sensor arranged on the force measuring ring and used for detecting the displacement of the force measuring ring in the vertical direction and/or a stress sensor arranged on the force-aid rod and/or a temperature sensor used for measuring the temperature of the soil sample and/or a displacement sensor probe used for measuring the displacement of the soil sample in the vertical direction and/or a water supplementing metering device used for measuring the water supplementing amount and the water supplementing rate.

2. The multifunctional frost heaving test system of claim 1, wherein the support frame comprises a lower plate and a guide rod fixed on the lower plate, the bottom of the lower plate is fixed with support legs, the lower cold plate is fixed on the lower plate, the upper reaction beam is slidably connected with the upper part of the guide rod, and the upper reaction beam can be fastened on the guide rod through a fastening connector.

3. The multifunctional frost heaving test system as claimed in claim 1, wherein a thermal insulation sleeve is arranged outside the test barrel body, the bottom of the thermal insulation sleeve is fixed on the lower cold plate or the support frame, an upper top plate capable of sealing an opening of the thermal insulation sleeve is arranged at the top of the test barrel body, the upper top plate is fixed on the lower cold plate or the support frame through a first pull rod, a through hole for the assistant rod to penetrate out is formed in the upper top plate, and the assistant rod is connected with the through hole in a sealing manner.

4. The multifunctional frost heaving test system of claim 1, wherein the lever force applying device comprises a lever assembly, a force bearing plate, and a fulcrum block fixed at the bottom of the support frame, wherein the lever assembly comprises a lever and a weight selectively assembled at one end of the lever, the middle part of the lever is hinged on the force bearing plate, the force bearing plate is slidably connected with a guide rod located below the support frame, the fulcrum block at the bottom of the fulcrum block is in contact with the lever, and the force bearing plate is fixed on the upper reaction beam through a second pull rod.

5. The multifunctional frost heaving test system of claim 4, wherein the other end of the lever is provided with a balance weight adjustable along the length direction of the lever, and the balance weight and the weight are respectively arranged at two ends of the lever.

6. The multifunctional frost heaving test system of claim 3, wherein a displacement sensor probe is fixed on the upper top plate in a downward direction, a measuring block is fixed on the boosting rod, and the displacement sensor probe detects the displacement of the soil sample at a distance from the measuring block;

the temperature sensor comprises a first temperature sensor which penetrates through the upper temperature control plate and is vertically inserted into the soil sample and/or one or more second temperature sensors which penetrate through the side wall of the test barrel body and are horizontally inserted into the soil sample.

7. The multifunctional frost heaving test system of claim 1, wherein the test barrel body comprises a first replaceable test barrel body and a second replaceable double-layer barrel body, wherein the first test barrel body comprises the inner sample barrel and a cooling portion disposed on the circumferential outer wall of the inner sample barrel, the second double-layer barrel body comprises an inner sample barrel and an outer sample barrel, the bottom of the inner sample barrel is hermetically connected with the lower cooling plate, the outer sample barrel is slidably sleeved outside the inner sample barrel, a small hole for inserting the second temperature sensor is formed in the side wall of the outer sample barrel, a strip-shaped hole for the second temperature sensor to penetrate is formed in the side wall of the inner sample barrel, and the length of the strip-shaped hole is greater than the aperture of the small hole.

8. The multifunctional frost heaving test system of claim 7, wherein the detection system further comprises a plurality of salinity sensors for testing salinity, the salinity sensors are inserted into the second double-layered barrel body at different heights, and reinforcing ribs are fixed on the side walls of the inner sample barrel of the second double-layered barrel body.

9. The multifunctional frost heave test system of claim 1, wherein the top of the booster rod is fixed to the bottom of the upper reaction beam, and the bottom of the booster rod is fixed with a force application disc coaxially fixed to the top surface of the upper temperature control plate.

10. The multifunctional frost heaving test system of claim 1, wherein the force-assisted rod comprises a positioning sleeve fixed at the bottom of the upper reaction beam, a force-bearing shaft fixedly sleeved in the positioning sleeve, and an upper temperature control plate reaction rod fixed at the top of the upper temperature control plate, wherein a groove is formed at the top of the upper temperature control plate reaction rod, the stress sensor is fixed in the groove, and the force-bearing shaft can be inserted into the groove in a matching manner to directly or indirectly act on the stress sensor;

11. The multifunctional frost heave test system of claim 1, wherein the cooling portion is a cooling jacket or a cooling coil disposed outside the inner sample barrel;

12. The multifunctional frost heaving test system of claim 1, wherein a sealing ring is disposed on a circumferential side wall of the upper temperature control plate.

13. The multifunctional frost heaving test system as claimed in claim 1, wherein the water replenishing plate and the lower cold plate enclose to form a water replenishing cavity, two water inlets are arranged on the water replenishing cavity, one of the water inlets is connected with the mahalanobis bottle through a water replenishing pipe, and the other water inlet is connected with a communicating hose to form a communicating vessel structure with the mahalanobis bottle;

14. The multifunctional frost heaving test system of claim 13, wherein the water replenishing plate and the annular flange disposed on the cold plate form a water replenishing cavity, the water replenishing plate comprises a bottom water permeable frame and an orifice plate fixed on the top of the bottom water permeable frame, wherein the bottom water permeable frame comprises ribs arranged in a grid crossing manner, and the ribs are provided with through water holes.

15. The test method of the multifunctional frost heaving test system of any one of claims 1 to 14, wherein the test method of the test apparatus comprises the steps of loading a soil sample into an inner sample barrel, and sealing the upper end and the lower end of the test barrel body by an upper temperature control plate and a lower cold plate so that the soil sample is in a relatively sealed state, and performing a coupling test in three aspects:

(3) constant stress or infinite stiffness or flexibility boundary conditions: when the upper counter-force beam is fixedly connected with the support frame and the force measuring ring is not arranged on the boosting rod, the displacement of the soil sample is completely limited, and a test under the condition of infinite rigidity is carried out;

when the upper counter-force beam 2 is fixedly connected with the support frame and the force measuring ring is arranged on the assistance rod, testing under a flexible boundary condition is carried out;

16. The testing method of claim 15, wherein when performing a single soil layer test, the testing barrel body adopts a first testing barrel body, and the temperature sensor adopts a first temperature sensor inserted into the soil sample from the upper temperature control plate;