阅读说明：本技术 一种氧化镁固化土碳化过程膨胀性及碳化土抗剪强度测试装置 (Device for testing expansibility and shear strength of carbonized soil in carbonization process of magnesium oxide solidified soil ) 是由 蔡光华 王中 赵志峰 邵光辉 刘成 张欣雅 于 2019-10-21 设计创作，主要内容包括：本发明公开了一种氧化镁固化土碳化过程膨胀性及碳化土抗剪强度测试装置,该装置将通气碳化装置、膨胀性测试装置、温度测试装置、电阻率测试装置、抗剪强度测试装置和控制器进行有序组合。温度传感器嵌入至电极板中心,实现温度和电阻率同步测试；将应变计布设在平衡板内和剪切盒的双层壳体内,通过液压杆和卷轴实现应变计自由工作；通过弹簧螺栓和柔性连接片实现剪切盒内壳的内径变化以及试样膨胀性和剪切强度精确测试。将剪切盒置于密封箱中,通过控制器实现各装置有序操作和数据采集,避免了碳化试样取样装样过程中的试样破损和应力释放,减小了外界环境对物理力学参数的影响,测试数据对碳化固化技术应用和碳化土地基设计具有重要意义。(The invention discloses a device for testing expansibility and shear strength of carbonized soil in a carbonization process of magnesia solidified soil. The temperature sensor is embedded into the center of the electrode plate to realize synchronous testing of temperature and resistivity; the strain gauge is arranged in the balance plate and the double-layer shell of the shearing box, and the free work of the strain gauge is realized through the hydraulic rod and the scroll; the inner diameter change of the inner shell of the shearing box and the accurate test of the expansibility and the shearing strength of the test sample are realized through the spring bolt and the flexible connecting sheet. The shear box is arranged in the seal box, ordered operation and data acquisition of all devices are realized through the controller, sample damage and stress release in the sample loading process of the carbonization sample are avoided, the influence of the external environment on physical mechanical parameters is reduced, and test data has important significance on the application of the carbonization curing technology and the design of the carbonized soil foundation.)

1. The device for testing the expansibility and the shear strength of the carbonized soil in the carbonization process of the magnesium oxide solidified soil is characterized in that: comprises a ventilation carbonization device, an expansibility testing device, a temperature testing device, a resistivity testing device, a shear strength testing device and a controller, wherein the ventilation carbonization device, the expansibility testing device, the temperature testing device, the resistivity testing device, the shear strength testing device and the controller are all fixed on an operation table,

the ventilating and carbonizing device comprises a fixed seat, a chute, a ball, a lower shearing box, a lower water permeable plate, a vent pipe, a thermostat, a pressure regulating valve, a high-pressure gas tank, a drain pipe, a drain valve, a seal box and a vent valve, wherein the fixed seat is fixedly arranged on the operating platform, the chute is arranged on the fixed seat, the ball is arranged between the chute and the lower shearing box, the seal box is fixedly arranged on the fixed seat through a bolt, the vent valve is arranged on the seal box, the lower shearing box is connected with the high-pressure gas tank through the vent pipe, the thermostat and the pressure regulating valve are arranged on the vent pipe, the drain pipe is,

the expansibility testing device comprises a lower shearing box, an upper water permeable plate, a balance plate, a strain gauge, an upper scroll, a connecting sheet, a spring bolt, an upper shearing box outer shell, an upper shearing box inner shell, a lower scroll, a lower shearing box outer shell, a lower shearing box inner shell and a reserved hole, wherein the lower shearing box comprises a lower scroll, a lower shearing box outer shell and a lower shearing box inner shell, the lower scroll is fixed on the lower shearing box outer shell, the lower shearing box inner shell is fixed in the lower shearing box outer shell through the spring bolt, the upper shearing box comprises an upper scroll, an upper shearing box outer shell and an upper shearing box inner shell, the upper scroll is fixed on the upper shearing box outer shell, the upper scroll and the lower scroll are both connected with the strain gauge, the strain gauge is arranged on the balance plate, and the strain gauge, the upper scroll and the lower scroll are connected on a controller through data lines,

the shear strength testing device comprises a supporting column, a cross beam, an upper shearing box, a hydraulic rod, a hydraulic cylinder, a propelling device, a speed regulator, a motor, a displacement sensor, a propelling rod, a dowel bar, a stress sensor, a controller, a pressure sensor, a control valve and an air compressor, wherein the supporting column and the propelling device are fixed on an operation table, the cross beam is fixed on the supporting column through bolts, the hydraulic cylinder is fixed at the lower part of the cross beam, the hydraulic rod and the pressure sensor are fixedly arranged at the lower part of the hydraulic cylinder, a balance plate is fixedly arranged at the bottom of the hydraulic rod, the hydraulic cylinder is connected onto the air compressor through a high-pressure pipe, the control valve is arranged on the high-pressure pipe, the speed regulator and the motor are fixedly arranged on the propelling device, the propelling rod is arranged between the propelling device and the lower shearing box, the displacement sensor is arranged on the propelling, a stress sensor is arranged on the dowel bar, the displacement sensor, the stress sensor and the pressure sensor are all connected on the controller through data lines,

the lower electrode plate, the temperature sensor and the upper electrode plate are connected to the controller through data lines, the temperature sensors are fixedly arranged at the centers of the lower electrode plate and the upper electrode plate, and preformed holes are formed in the upper electrode plate, the upper permeable plate, the upper shearing box inner shell and the lower shearing box inner shell.

2. The device for testing the expansibility during the carbonization process of magnesia curing soil and the shear strength of carbonized soil according to claim 1, wherein the strain gauges connected with the upper reel and the lower reel are distributed in a ring shape, the inner shell of the upper shear box and the inner shell of the lower shear box are both in a bivalve cylindrical structure, and the two lobes of the inner shell of the upper shear box and the two lobes of the inner shell of the lower shear box are connected through connecting pieces.

3. The device for testing the expansibility during the carbonization of magnesia curing soil and the shear strength of carbonized soil according to claim 1, wherein the contact points between the hydraulic cylinder, the push rod and the dowel bar and the seal box are all sealed.

4. The device for testing expansibility during carbonization of magnesia-solidified soil and shear strength of carbonized soil according to claim 1, wherein the connecting plate is made of an insulating flexible material, the number of the upper reel is one or two, the number of the lower reel is one or two, and the upper reel and the lower reel can be fixed in a butt joint manner through nut holes.

5. The apparatus for testing expansive nature and shear strength of carbonized soil during the carbonization process of magnesia solidified soil according to claim 1, wherein the inner casings of the upper shear box and the lower shear box have the same size, the outer casings of the upper shear box and the lower shear box have the same size, and the connection of the upper reel and the lower reel stabilizes the lower shear box and the upper shear box as a whole.

6. The device for testing the expansibility during carbonization of magnesia curing soil and the shear strength of carbonized soil according to claim 1, wherein the central holes of the lower electrode plate and the upper electrode plate and the prepared holes of the upper electrode plate are provided with insulating linings, and the inner shells of the upper shear box and the lower shear box are made of hard materials which are insulating and corrosion-resistant.

Background

With the development of economy and urbanization in China, the foundation construction of urban construction, traffic and water conservancy and the like often meets soft soil layers with different thicknesses, and the soft soil has the characteristics of high water content, large porosity, low strength, high compressibility and the like, so that great challenges are brought to engineering construction and foundation treatment. In the common foundation treatment methods, the construction of a dynamic compaction method and a vibroflotation method is difficult to implement due to large noise, and the traditional replacement and filling method is rarely recommended due to large engineering quantity, high cost and uneven distribution of bearing capacity. The pile foundation reinforcing method of cement/lime soil pile, grouting method, high pressure jet grouting pile and the like is the most used technology at present, the method has long treatment and maintenance period, the used curing materials mainly comprise cement and lime, the energy resource consumption in the cement production process is large, the environmental pollution is serious, and a plurality of negative effects are brought to the sustainable development of economy and environment, so that geotechnical engineering researchers begin to seek new alternative materials and methods. In recent years, the subject group adopts active magnesium oxide and carbon dioxide as curing agents to replace the traditional cement to carry out the curing treatment of weak soil, and discloses a series of invention patents: such as "a method for carbonizing and solidifying soil (201210097042.2)", "a method for carbonizing and solidifying soil and a device thereof (201010604013.1)", "a treatment system and a method for thermally consolidating soft soil foundation using industrial waste gas (201310122135.0)", "a treatment system and a method for forming carbonized pile (2014102039788)" for consolidating foundation "," a method for carbonizing and consolidating replacement mat layer of soft soil foundation (2014102729571) "," a treatment method for in situ carbonizing and solidifying shallow soft foundation (201510348797.9) ", and" a carbonized-stirred pile-air-permeable pile composite foundation and a construction method thereof (201710225231.6) ", etc. The invention patents are soft soil treatment construction technologies disclosed based on a magnesium oxide-carbon dioxide solidification mechanism. However, after the soft soil is carbonized, the physical characteristics and the mechanical characteristics of the soil body are changed greatly, which has important influence on geotechnical engineering construction. Aiming at the particularity of soft soil carbonization and solidification treatment, in the engineering design process of the carbonization treatment foundation, the method tests the expansibility and the shearing resistance of the carbonization and solidification soil and is particularly important for reasonably determining the physical characteristics, the bearing capacity of the foundation soil and the strength parameters (cohesive force and internal friction angle).

As is known, the carbonization reaction of the magnesium oxide mixed soil is a chemical strengthening process with heat release and expansion, the strength is increased quickly, the temperature is increased, and the sample expansion is obvious, because the existing indoor direct shear test is carried out based on a cutting ring sample, the carbonized soil sample is difficult to carry out cutting ring sampling; if the magnesium oxide mixed soil sample is pressed in a cutting ring and then carbonized, the real carbonization process of the sample is difficult to reflect. The expansibility evaluation of the magnesium oxide cured sample mainly comprises the steps of testing the sizes of an indoor cylindrical sample before and after carbonization and averaging, and no accurate testing method is available for evaluating the expansibility of the sample in the carbonization and curing process. The existing expansibility testing device and method mostly concentrate on the geotechnical engineering field, mostly adopt the equilibrium pressurization method, the counter-pressure method and the decompression method to carry out, easily cause the sample to destroy; and the expansibility testing device is few and the cost is high. Although the document discloses a device and a method (201710399344.8) for testing the expansibility of an expansive grouting material in a curing process, the device and the method disclose the expansibility of the grouting material by adopting an elastic constraint part to control the curing expansion deformation of the material and measuring the corresponding expansion force and the change characteristics of the expansion force along with time under different constraint conditions.

At present, the soil layer is subjected to direct shear test by adopting traditional direct shear apparatus mostly at home and abroad, and the shear apparatus mainly comprises a shear box, a vertical loading device, a horizontal loading device and the like. In the traditional direct shear test, a cutting ring is often used for cutting a soil sample to be tested into a specific shape and moving the soil sample into a shear box, and the soil sample is easily disturbed and damaged in the moving and cutting processes, so that the experimental data is inaccurate. The existing direct shear apparatus is mainly reconstructed based on special environment, for example, a chemical corrosion apparatus is added to simulate the field soil pollutant corrosion by a file 'determination method of chemical polluted soil shear strength and a special full-automatic direct shear apparatus (2016100447885)', so as to solve the problem that the conventional direct shear tester can not test the shear strength parameters of the chemical polluted soil; the temperature control type direct shear apparatus (201110079021.3) is characterized in that a sample is placed in a constant temperature water tank, the temperature is controlled by a water temperature detection unit and a measurement mechanism, and the shear strength test of the sample at constant temperature is completed; the large multifunctional frozen soil-structure contact surface circulating direct shear apparatus and the test operation method (201210265653.3) cool a soil sample through refrigerating fluid of a refrigerating device, simultaneously record the temperature of the soil sample in real time through a high-precision temperature sensor, and can replace steel plates with different roughness to simulate contact surfaces with different roughness, thereby completing the shear strength test of frozen soil; the frozen soil-structure direct shear apparatus and the using method (201110186321.1) thereof are characterized in that a semiconductor refrigerating block is arranged at the bottom of a shearing box, a cooling liquid conveying pipe in a low-temperature constant-temperature groove is connected with the semiconductor refrigerating block, different freezing conditions are simulated, and a relation curve of shear stress and shear displacement of a frozen soil-structure contact surface is measured; an unsaturated soil-structure material contact surface shear apparatus (2019100476218) for controlling relative humidity is provided with a closed pressure chamber and a humidity environment control module to simulate different humidity and pressure environments so as to reproduce the humidity state of an actual engineering site and obtain controllable unsaturated soil-structure material contact surface mechanical characteristics which have wide suction range and are suitable for different soil types and different structure materials; the combined indoor consolidation shearing instrument (2018115645426) is provided with a vertical loading device and a horizontal loading device, and directly carries out a shearing test on a sample after consolidation is completed, so that the consolidation coefficients and the shear strengths of different types of soil bodies are continuously determined. Although the direct shear apparatus is greatly improved compared with the traditional direct shear apparatus, soil body direct shear tests under different environments are simulated, but the expansibility of a soil body in the carbonization process and the shear strength test of the carbonized soil body cannot be met, and the detection of the temperature and the resistivity of a soil sample in the carbonization process cannot be completed.

Based on the current situation of rapid development of engineering construction and the advantages of a novel carbonization and reinforcement method in China, and combining the current situations of difficult parameter testing, inaccurate mechanical parameter testing and the like in the current carbonization and reinforcement process, the device for testing the expansibility and the shear strength of the carbonized soil in the carbonization process of the magnesia solidified soil needs to be researched and developed urgently, and has important significance in the aspects of effectively utilizing carbon dioxide, reasonably carrying out engineering design and application and the like.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a device for testing the expansibility and the shear strength of the carbonized soil in the carbonization process of the magnesia curing soil, which realizes the synchronous test of temperature and resistivity and reasonably evaluates the carbonization process of the magnesia mixed soil. The strain gauge is arranged in the balance plate and the double-layer structure shell of the shearing box, the strain gauge can work freely through the adjustment of the hydraulic rod and the scroll, the inner diameter change of the inner shell of the shearing box is realized through the spring bolt and the flexible connecting sheet in the shearing box, and the accurate test of the expansibility and the shearing strength of a sample is realized. The shearing box is arranged in the carbonization sealing box, and the ordered operation and data acquisition of each device are realized through the controller, so that the damage and stress release of a sample in the sample loading process of a carbonization sample are avoided, the influence of the external environment on the shearing strength parameter is reduced, and the measured parameter has important significance on the engineering application and design of the magnesium oxide carbonization solidified soil.

In order to achieve the aim, the invention discloses a device for testing the expansibility and the shear strength of carbonized soil in the carbonization process of magnesia solidified soil, which is characterized by comprising a ventilating carbonization device, an expansibility testing device, a temperature testing device, a resistivity testing device, a shear strength testing device and a controller, wherein the ventilating carbonization device, the expansibility testing device, the temperature testing device, the resistivity testing device, the shear strength testing device and the controller are all fixed on an operation table,

the ventilating and carbonizing device comprises a fixed seat, a chute, a ball, a lower shearing box, a lower water permeable plate, a vent pipe, a thermostat, a pressure regulating valve, a high-pressure gas tank, a drain pipe, a drain valve, a seal box and a vent valve, wherein the fixed seat is fixedly arranged on the operating platform, the chute is arranged on the fixed seat, the ball is arranged between the chute and the lower shearing box, the seal box is fixedly arranged on the fixed seat through a bolt, the vent valve is arranged on the seal box, the lower shearing box is connected with the high-pressure gas tank through the vent pipe, the thermostat and the pressure regulating valve are arranged on the vent pipe, the drain pipe is,

the expansibility testing device comprises a lower shearing box, an upper water permeable plate, a balance plate, a strain gauge, an upper scroll, a connecting sheet, a spring bolt, an upper shearing box outer shell, an upper shearing box inner shell, a lower scroll, a lower shearing box outer shell, a lower shearing box inner shell and a reserved hole, wherein the lower shearing box comprises a lower scroll, a lower shearing box outer shell and a lower shearing box inner shell, the lower scroll is fixed on the lower shearing box outer shell, the lower shearing box inner shell is fixed in the lower shearing box outer shell through the spring bolt, the upper shearing box comprises an upper scroll, an upper shearing box outer shell and an upper shearing box inner shell, the upper scroll is fixed on the upper shearing box outer shell, the upper scroll and the lower scroll are both connected with the strain gauge, the strain gauge is arranged on the balance plate, and the strain gauge, the upper scroll and the lower scroll are connected on a controller through data lines,

the shear strength testing device comprises a supporting column, a cross beam, an upper shearing box, a hydraulic rod, a hydraulic cylinder, a propelling device, a speed regulator, a motor, a displacement sensor, a propelling rod, a dowel bar, a stress sensor, a controller, a pressure sensor, a control valve and an air compressor, wherein the supporting column and the propelling device are fixed on an operation table, the cross beam is fixed on the supporting column through bolts, the hydraulic cylinder is fixed at the lower part of the cross beam, the hydraulic rod and the pressure sensor are fixedly arranged at the lower part of the hydraulic cylinder, a balance plate is fixedly arranged at the bottom of the hydraulic rod, the hydraulic cylinder is connected onto the air compressor through a high-pressure pipe, the control valve is arranged on the high-pressure pipe, the speed regulator and the motor are fixedly arranged on the propelling device, the propelling rod is arranged between the propelling device and the lower shearing box, the displacement sensor is arranged on the propelling, a stress sensor is arranged on the dowel bar, the displacement sensor, the stress sensor and the pressure sensor are all connected on the controller through data lines,

the lower electrode plate, the temperature sensor and the upper electrode plate are connected to the controller through data lines, the temperature sensors are fixedly arranged at the centers of the lower electrode plate and the upper electrode plate, and preformed holes are formed in the upper electrode plate, the upper permeable plate, the upper shearing box inner shell and the lower shearing box inner shell.

As an improvement of the invention, the strain gauges connected with the upper scroll and the lower scroll are distributed in an annular net shape, the inner shell of the upper shearing box and the inner shell of the lower shearing box are both in a double-petal cylindrical structure, and the two petals of the inner shell of the upper shearing box and the two petals of the inner shell of the lower shearing box are both connected through connecting sheets.

As another improvement of the invention, the contact positions among the hydraulic cylinder, the push rod and the dowel bar and the seal box are all sealed.

As another improvement of the invention, the connecting piece is made of an insulating flexible material, the number of the upper winding shafts is one or two, the number of the lower winding shafts is one or two, and the upper winding shafts and the lower winding shafts can be butted and fixed through the nut holes.

As another improvement of the present invention, the upper shear box inner housing and the lower shear box inner housing are of the same size, the upper shear box outer housing and the lower shear box outer housing are of the same size, and the connection of the upper spool and the lower spool stabilizes the lower shear box and the upper shear box as a unit.

As another improvement of the invention, the central holes of the lower electrode plate and the upper electrode plate and the preformed holes of the upper electrode plate are provided with insulating linings, and the inner shells of the upper shearing box and the lower shearing box are made of insulating and anticorrosive hard materials.

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

1) temperature sensors and electrode plates are specially arranged at two ends of the sample, and probes of the temperature sensors are embedded into the centers of the electrode plates, so that synchronous testing of temperature and resistivity is realized, and evaluation of a carbonization process is facilitated;

2) the strain gauge is arranged in the balance plate and the double-layer shell of the shearing box, and the strain gauge is protected by adjusting the hydraulic rod and the reel and realizes free work of the strain gauge;

3) the inner diameter change of the inner shell of the shear box, the expansibility and the shear strength of a carbonized sample are realized through the synergistic effect of the spring bolt and the flexible connecting sheet in the double-layer shell of the shear box, so that the test result is closer to the in-situ processed soil sample;

4) all the sensors, the scroll and the spring bolts are connected with the integrated controller, so that the structure is unified, the system continuity is stronger, the operation is easy, the operation is convenient, and the test operation time is reduced;

5) a thermostat is specially arranged on the vent pipe, and a drain pipe is arranged at the bottom of the lower shearing box, so that the condensation of an air pipe and the accumulation of water vapor at the bottom of the shearing box caused by low-temperature compressed gas are avoided;

6) the shear box is arranged in the seal box, the sample does not need to move after carbonization, the damage and stress release of the sample in the sampling and sample loading process of the carbonized sample are avoided, the influence of the external environment on physical mechanical parameters is reduced, and the test data has important significance on the application of the carbonization and solidification technology and the design of the carbonized soil foundation;

7) the device realizes the reinforcement of environment-friendly magnesium oxide to the soil body, absorbs a large amount of carbon dioxide gas in the reinforcement process, and has the advantages of low carbon, environmental protection and sustainable development.

Drawings

FIG. 1 is a schematic structural diagram of a device for testing expansibility and shear strength of carbonized soil during carbonization of magnesia-cured soil;

FIG. 2 is a cross-sectional view of the upper and lower shear boxes;

FIG. 3 is a plan view of the upper shear box;

FIG. 4 is a plan view of the balance plate;

FIG. 5 is a plan view of the upper permeable stone;

FIG. 6 is a plan view of an upper electrode plate;

in the figure: 1. an operation table, 2, a fixed seat, 3, a sliding chute, 4, a ball, 5, a lower shearing box, 6, a lower water permeable plate, 7, a lower electrode plate, 8, a temperature sensor, 9, a sample, 10, a vent pipe, 11, a constant heater, 12, a pressure regulating valve, 13, a high-pressure gas tank, 14, a drain pipe, 15, a drain valve, 16, a support column, 17, a seal box, 18, an exhaust valve, 19, a cross beam, 20, an upper shearing box, 21, an upper electrode plate, 22, an upper water permeable plate, 23, a balance plate, 24, a hydraulic rod, 25, a hydraulic cylinder, 26, a propulsion device, 27, a speed regulator, 28, a motor, 29, a displacement sensor, 30, a propulsion rod, 31, a force transmission rod, 32, a stress sensor, 33, a controller, 34, a pressure sensor, 35, a strain gauge, 36, an upper scroll, 37, a control valve, 38, an air compressor, 39, a connecting sheet, 40, a, 42. an upper cutting box inner shell, 43, a lower scroll, 44, a lower cutting box outer shell, 45, a lower cutting box inner shell, 46 and a reserved hole.

Detailed Description

In the description of the present invention, it should be understood that the orientations and positional relationships indicated by the terms "upper", "lower", "top", "bottom", "inner", "outer", and the like are based on the orientations and positional relationships shown in the drawings, and are only for convenience of description of the present invention, and do not indicate or imply any particular orientation which is necessary in the device to which the present invention is directed, and therefore, the present invention should not be construed as being limited. In order to make the technical means, the creation characteristics, the achievement purposes and the effects of the invention easy to understand, the invention is further explained below by combining the figures.

The device for testing the expansibility and the shear strength of the carbonized soil in the carbonization process of the magnesia solidified soil is characterized by comprising a ventilating carbonization device, an expansibility testing device, a temperature testing device, a resistivity testing device, a shear strength testing device and a controller 33, wherein the ventilating carbonization device, the expansibility testing device, the temperature testing device, the resistivity testing device, the shear strength testing device and the controller 33 are all fixed on an operation table 1,

the ventilating and carbonizing device comprises a fixed seat 2, a chute 3, a ball 4, a lower shearing box 5, a lower water permeable plate 6, a vent pipe 10, a thermostat 11, a pressure regulating valve 12, a high-pressure gas tank 13, a drain pipe 14, a drain valve 15, a seal box 17 and a vent valve 18, wherein the fixed seat 2 is fixedly arranged on an operation table 1, the chute 3 is arranged on the fixed seat 2, the ball 4 is arranged between the chute 3 and the lower shearing box 5, the seal box 17 is fixedly arranged on the fixed seat 2 through a bolt, the vent valve 18 is arranged on the seal box 17, the lower shearing box 5 is connected with the high-pressure gas tank 13 through the vent pipe 10, the thermostat 11 and the pressure regulating valve 12 are arranged on the vent pipe 10, the drain pipe 14 is arranged at the,

the expansibility testing device comprises a lower shearing box 5, an upper shearing box 20, an upper water permeable plate 22, a balance plate 23, a strain gauge 35, an upper reel 36, a connecting sheet 39, a spring bolt 40, an upper shearing box outer shell 41, an upper shearing box inner shell 42, a lower reel 43, a lower shearing box outer shell 44, a lower shearing box inner shell 45 and a reserved hole 46, wherein the lower shearing box 5 consists of a lower reel 43, a lower shearing box outer shell 44 and a lower shearing box inner shell 45, the lower reel 43 is fixed on the lower shearing box outer shell 44, the lower shearing box inner shell 45 is fixed in the lower shearing box outer shell 44 through the spring bolt 40, the upper shearing box 20 consists of an upper reel 36, an upper shearing box outer shell 41 and an upper shearing box inner shell 42, the upper reel 36 is fixed on the upper shearing box outer shell 41, the upper shearing box inner shell 42 is fixed on the upper shearing box outer shell 41 through the spring bolt 40, the upper reel 36 and the lower reel 43 are connected with the strain gauge 35, the balance plate 23 is provided with a strain gauge 35, the strain gauge 35, an upper reel 36 and a lower reel 43 are connected with the controller 33 through data lines,

the shear strength testing device comprises a supporting column 16, a cross beam 19, an upper shear box 20, a hydraulic rod 24, a hydraulic cylinder 25, a propelling device 26, a speed regulator 27, a motor 28, a displacement sensor 29, a propelling rod 30, a transmission rod 31, a stress sensor 32, a controller 33, a pressure sensor 34, a control valve 37 and an air compressor 38, wherein the supporting column 16 and the propelling device 26 are fixed on an operation table 1, the cross beam 19 is fixed on the supporting column 16 through bolts, the hydraulic cylinder 25 is fixed on the lower portion of the cross beam 19, the hydraulic rod 24 and the pressure sensor 34 are fixedly arranged on the lower portion of the hydraulic cylinder 25, a balance plate 23 is fixedly arranged at the bottom of the hydraulic rod 24, the hydraulic cylinder 25 is connected onto the air compressor 38 through a high-pressure pipe, the control valve 37 is arranged on the high-pressure pipe, the speed regulator 27 and the motor 28 are fixedly arranged on the propelling device 26, the propelling rod, a displacement sensor 29 is arranged on the push rod 30, the dowel bar 31 is fixed on the support column 16 and positioned between the support column 16 and the shearing box 20, a stress sensor 32 is arranged on the dowel bar 31, the displacement sensor 29, the stress sensor 32 and the pressure sensor 34 are all connected on a controller 33 through data lines,

the lower electrode plate 7, the temperature sensor 8 and the upper electrode plate 21 are all connected to the controller 33 through data lines, the temperature sensor 8 is fixedly arranged at the centers of the lower electrode plate 7 and the upper electrode plate 21, the upper permeable plate 22, the upper shearing box inner shell 42 and the lower shearing box inner shell 45 are all provided with reserved holes 46.

As a modification of the invention, the strain gauges 35 connected with the upper reel 36 and the lower reel 43 are distributed in a ring net shape, the upper shear box inner shell 42 and the lower shear box inner shell 45 are both of a double-lobe cylindrical structure, and the two lobes of the upper shear box inner shell 42 and the two lobes of the lower shear box inner shell 45 are connected through the connecting sheet 39.

As a modification of the present invention, the contact positions between the hydraulic cylinder 25, the push rod 30, the transmission rod 31 and the seal box 17 are all sealed.

The device for testing the expansibility and the shear strength of the carbonized soil in the carbonization process of the magnesia curing soil disclosed by the invention can realize test operation through the following steps:

firstly, assembling and connecting the device, sequentially placing a lower porous plate 6, filter paper, a lower electrode plate 7 and a temperature sensor 8 in a lower shearing box 5, placing an upper shearing box 20 on the lower shearing box 5, adjusting all spring bolts 40 in the shearing box to tightly close two petals of an inner shell 42 of the upper shearing box and two petals of an inner shell 45 of the lower shearing box, coating vaseline on the inner walls of the inner shell 42 of the upper shearing box and the inner shell 45 of the lower shearing box, adjusting an upper scroll 36 and a lower scroll 43 and butting the upper scroll and the lower scroll into a whole, so that the lower shearing box 5 and the upper shearing box 20 are stabilized into a whole;

then, preparing a sample in a shearing box, preparing a magnesium oxide mixed soil sample 9 under different compactedness by using a cutting ring, extruding the sample from the cutting ring into the shearing box by using a stripper, enabling the bottom of the sample to be tightly contacted with a temperature sensor and a lower electrode plate 7, and then sequentially placing an upper electrode plate 21, a temperature sensor 8, filter paper and an upper permeable plate 22 on the top of the sample 9 so as to enable the preformed holes 46 of the upper electrode plate 21 and the upper permeable plate 22 to correspond to each other;

then, debugging sensors, namely adjusting all the spring bolts 40 to expand the inner diameters of the upper shearing box inner shell 42 and the lower shearing box inner shell 45, then rotating the upper reel 36 and the lower reel 43 to enable the strain gauge 35 to extend out of the reserved holes 46 of the upper shearing box inner shell 42 and the lower shearing box inner shell 45 and to be in contact with the side face of the sample 9, opening the air compressor 38 and the control valve 37 and adjusting the hydraulic rod 24 to enable the strain gauge 35 on the balance plate 23 to penetrate through the reserved holes 46 of the upper permeable plate 22 and the upper electrode plate 21 to enable the strain gauge 35 to be in contact with the upper top face of the sample 9, and finally opening a data acquisition device in the controller 33 to record initial readings of all the strain gauges 35, the temperature sensors 8 and the resistivity;

the method comprises the following steps of (1) carrying out sample carbonization maintenance and physical parameter testing in a carbonization process, mounting a sealing box 17 without a bottom cover on a fixed seat, closing a drain valve 15 and an exhaust valve 18, opening a constant heater 11, adjusting a pressure regulating valve 12 to a preset pressure, carrying out ventilation and carbonization, closing the pressure regulating valve 12, opening the drain valve 15 and the exhaust valve 18 after specified ventilation time is finished, and carrying out standard maintenance; deformation, temperature and resistivity are monitored in real time through the strain gauge 35, the temperature sensor 8, the lower electrode plate 7 and the upper electrode plate 21 in the ventilation carbonization and maintenance processes;

finally, direct shear test preparation and direct shear test: after sample carbonization and maintenance are finished, manually adjusting the push rod 30 to enable the push rod 30 to be in contact with the lower shear box shell 44, and enabling the upper shear box shell 41 to be in contact with the dowel bar 31; rotating the upper reel 36 to contract the strain gauge 35 to the rear of the upper shear box inner case 42 and the lower shear box inner case 45 and separate the upper reel 36 and the lower reel 43, and adjusting and unscrewing all the spring bolts 40 to bring the front of the upper shear box inner case 42 and the lower shear box inner case 45 into close contact with the surface of the carbonized specimen 9; adjusting the control valve 37 and rotating the hydraulic rod 24 to make the strain gauge 35 contract from the preformed hole 46 to the balance plate 23, adjusting the hydraulic rod 24 to make the upper permeable plate 22 closely contact with the filter paper on the upper electrode plate 21, adjusting the hydraulic cylinder 25 and the hydraulic rod 24 to make the pressure sensor 34 stabilize to a preset pressure value, and recording initial readings of the displacement sensor 29 and the pressure sensor 32; starting a motor 28 in the propelling device 26, adjusting a speed regulator 27 to enable the lower shearing box 5 and the upper shearing box 20 to generate shearing movement, recording a displacement sensor 29, a stress sensor 32 and a resistivity value during the shearing process, and calculating shearing parameters of the carbonized sample 9.

The foregoing shows and describes the general principles, essential features, and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited by the foregoing examples, which are provided to illustrate the principles of the invention, and that various changes and modifications may be made without departing from the spirit and scope of the invention, which is also intended to be covered by the appended claims. The scope of the invention is defined by the appended claims and equivalents thereof.