CN114518292A - Model test device and test method for high-speed railway roadbed of inclined crossing karez - Google Patents
Model test device and test method for high-speed railway roadbed of inclined crossing karez Download PDFInfo
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- CN114518292A CN114518292A CN202210153381.1A CN202210153381A CN114518292A CN 114518292 A CN114518292 A CN 114518292A CN 202210153381 A CN202210153381 A CN 202210153381A CN 114518292 A CN114518292 A CN 114518292A
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
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Abstract
The invention discloses a model test device and a test method for a high-speed railway roadbed of an inclined crossing karez, which comprises a reaction frame, a model device, a loading device, a monitoring system and a data acquisition system, wherein the reaction frame is arranged on the back of the model device; the model device comprises a concealed channel and a vertical shaft for simulating the karst well by adopting PVC pipes, and the influence of the uphill roadbed load and the dynamic load of a high-speed train on the structural stability of the roadbed is researched by setting the intersection angle between different concealed channels and the roadbed load central line and the buried depth of the concealed channel when the high-speed railway roadbed inclines to cross the karst well. The method can determine the influence mechanism of the intersection angle and the burial depth on the collapse mechanism of the shallow-buried well underdrain, evaluate the interaction influence range of the high-speed railway subgrade and the inclined crossing well underdrain under the dynamic load of the train, establish the foundation for evaluating the stability of the high-speed railway subgrade crossing different intersection angles and the buried depth well underdrain, and fill the technical blank in the aspect of indoor model test devices of the high-speed railway subgrade inclined crossing well underdrain region in China.
Description
Technical Field
The invention relates to the technical field of geotechnical engineering, in particular to a model test device and a test method for a high-speed railway roadbed of an inclined crossing karez.
Background
The karez is an old underground water conservancy irrigation project which utilizes shallow underground water for self-flow irrigation in arid and semiarid regions, and is mainly distributed in Xinjiang in China. The karez is composed of a vertical shaft excavated manually, a covered channel with a certain longitudinal slope, an open channel for water delivery on the ground and a small reservoir. The hidden channel is the main part of the karst well, and the slope of the hidden channel is smaller than the slope of the ground and the slope of the underground water surface, so that the underground water can be automatically led out of the ground, and the hidden channel is used for agricultural irrigation and resident life. The vertical shafts are distributed along the underdrains, are generally spaced at intervals of about 15-30 m, are communicated with the underdrains at the bottoms, are generally 5-60 m deep, can reach more than 80m at the maximum, and mainly play roles in ventilation and soil discharging during construction.
There is a different degree of extinction in the well around the world today, the main cause of which is collapse of the well, especially of unreinforced underdrains, caused by various natural and man-made factors. In engineering research, the submarine canals of the karst wells have structural forms similar to goafs, karst caves and the like of mines. For the karr well spanned by the high-speed railway subgrade, the unreinforced underdrains are likely to collapse under the action of subgrade load and load generated during the running of a train, so that the connected subgrade is damaged, and the stability of the upper high-speed railway subgrade and the running safety of the train are further influenced. It is therefore necessary to study the stability of the underdrain of the high-speed rail line under load.
The new high-speed railway base project is always inclined to cross over the covered channel of the karez. Aiming at the karez, when the high-speed rail subgrade is pressed on a hidden canal of the karez at different intersection angles, the external force action effects are different, so that the karez generates different mechanical responses. Therefore, an influence mechanism of intersection angles on interaction between the canyon underdrains and the roadbed above needs to be determined, so that a stability evaluation method for crossing the canyon underdrains at different intersection angles is established, and the reinforcement treatment range of the roadbed of the high-speed railway crossing the canyons in a tilting manner is determined.
At present, no design scheme related to the high-speed railway roadbed in the karez area exists in China, the technical blank in the aspect of indoor model test devices of the karez area of the high-speed railway roadbed in China can be filled by the method, and a force is contributed to the construction of high-speed rails in the northwest area of China and other countries.
Disclosure of Invention
Aiming at the problems in the prior art, the invention aims to provide a model test device and a test method for a high-speed railway roadbed crossing a karez, which are used for researching the influence of different intersection angles of underdrains and lines and the depth from the underdrains to an upper foundation on the collapse mechanism of the karez underdrains, further analyzing the stability of the karez-crossing high-speed railway roadbed structure, determining the reinforcement processing range required by the karez-crossing karez high-speed railway roadbed under the action of dynamic load of a high-speed train, and solving the problem that the prior art has technical blank in the aspect of researching the indoor model test device in the karez area of the high-speed railway roadbed.
In order to achieve the purpose of the invention, the technical scheme adopted by the invention is as follows:
the joint structure for the tunnel corrugated plate supporting structure comprises a reaction frame, a model device, a loading device, a monitoring system and a data acquisition system;
the model device comprises a model box, wherein a model subgrade and a model foundation arranged below the model subgrade are arranged in the model box, and a karez underdrain and a karez shaft which are simulated by adopting PVC pipes are arranged in the model foundation; the intersection angle theta of the karez underdrain and the line is 0-90 degrees, and collapse damage and deformation rules of the karez underdrain are obtained under different intersection angles theta;
the loading device is connected with the reaction frame and is used for applying static load and dynamic load to the model roadbed;
the monitoring system comprises displacement meters arranged on the surfaces of the model roadbed and the model foundation, strain gauges arranged on the surfaces of the karez underdrain and the karez shaft, soil pressure boxes arranged in the model roadbed and the model foundation and a water content meter arranged in the model foundation; the data acquisition system is electrically connected with the monitoring system.
Further, the model box comprises a frame made of section steel and transparent tempered glass arranged on the side wall of the frame; the inside dimension of the mold box is 2.0m × 2.0m × 1.5m, and the thickness of the transparent tempered glass is 30 mm.
Furthermore, the loading device comprises a jack for applying a static load to the model roadbed and a servo vibration exciter for applying a dynamic load to the model roadbed, wherein the servo vibration exciter is used for simulating the dynamic load applied to the model roadbed by the high-speed railway train, the dynamic load frequency of the servo vibration exciter is 5Hz, and the dynamic load dynamic stress amplitude is 10 kN.
Furthermore, the loading device further comprises a loading plate, a concrete cushion layer is arranged on the lower surface of the loading plate, and the jack and the servo vibration exciter apply static load and dynamic load to the model roadbed through the loading plate.
Furthermore, water bags with remote switch valves are arranged in the canyon underdrain and the canyon shaft.
Furthermore, a buffer device is arranged between the model foundation and the inner wall of the model box and comprises a buffer pad and a rigid baffle, the two side walls of the buffer pad are respectively contacted with the side wall of the model foundation and the side wall of the rigid baffle, and the other side wall of the rigid baffle is contacted with the inner wall of the model box.
The scheme also provides a test method of the model test device for the high-speed railway roadbed crossing the karez, which is used for researching the influence of different underdrains and line intersection angles and the depth from the underdrains to the upper foundation on the collapse mechanism of the karez underdrains, further analyzing the stability of the roadbed structure of the high-speed railway crossing the karez, and determining the reinforcement treatment range required by the karez high-speed railway roadbed crossing the karez under the action of dynamic load of a high-speed train, wherein the test method comprises the following steps:
S1: model size calculation
Setting a model test similarity ratio by taking the non-occurrence boundary effect as a reference, and calculating the sizes of a model roadbed filled in the model box, a model foundation and a PVC pipe and the quality of required filled soil according to the similarity ratio;
s2: filling sample
Adopting a shakeout method for layered filling, and leveling and compacting each layer of similar material after filling is finished to ensure that the dry density of each layer of soil is the same in the filling process; under the designed buried depth, placing a PVC pipeline into the model foundation to simulate a campylon underdrain or a vertical shaft; the intersection angle between the karez underdrain and a line is theta, the intersection angle theta is 0-90 degrees, a water sac is placed in a PVC pipeline of the simulated karez underdrain in advance, after filling of a model foundation is completed, the water sac is drained, and the simulated karez underdrain without supporting cavities is obtained;
s3: arrangement monitoring system
Burying a soil pressure box and a water content meter in the model roadbed and the model foundation, mounting a strain meter on a PVC pipeline, and mounting a displacement meter on the surface of the model roadbed and the model foundation; electrically connecting the soil pressure cell, the water content meter, the strain gauge and the displacement meter with a data acquisition system; the data acquisition system tests whether the reading of the monitoring system is normal, if so, the step 4 is carried out, otherwise, the data acquisition system is checked until the reading is normal;
S4: placement loading device
The loading device is connected with the reaction frame, and a concrete cushion layer is arranged on the loading plate;
s5: dead load loading
Loading the sample by a jack, recording data once at intervals of 1min, stopping loading when the jack is loaded to be higher than the load of the train, and recording and arranging the data;
s6: dynamic load loading
The vibration exciter loads a sample in a sine wave form with the amplitude of 5kN and the frequency of 10Hz, is used for simulating the load of a high-speed train, observes and records the data of a monitoring system, and stops loading the sample until a PVC pipe is damaged or the power cycle frequency reaches 10000 times;
s7: unloading;
s8: and analyzing and determining the interaction of the karez to the high-speed railway roadbed according to the physical parameters acquired by the monitoring system.
Step S8 further includes:
the data of the soil pressure cell is used for obtaining the soil pressure distribution in the model subgrade and the model foundation structure in the dynamic load stage, further obtaining the attenuation law of dynamic stress in the horizontal direction and the vertical direction, and obtaining the influence distribution and the action range of high-speed railway load on the subgrade;
obtaining settlement of the model subgrade and the model foundation in the dynamic load stage according to the displacement parameters acquired by the displacement meter, and obtaining the influence of the existence of the karez on the subgrade settlement;
Obtaining the strain quantities of the canyon underdrain and the canyon shaft in the dynamic loading stage according to the strain parameters collected by the strain gauge, and obtaining the influence of train load on deformation of the canyon; the model test results were used to evaluate the slope of the highway subgrade across the karez interaction range of influence.
Further, the method for determining the influence range of the high-speed railway subgrade inclined across the karez interaction according to the model test result comprises the following steps:
analyzing attenuation laws sigma x and sigma y of the dynamic stress in the horizontal direction and the vertical direction to obtain an influence range s1 of the high-speed rail load; analyzing the settlement d of the karez foundation under dynamic load to obtain the influence s2 of the karez on the settlement of the foundation; analyzing the deformation Qy of the karez and the deformation Qx of the shaft at different positions under the dynamic load to obtain the influence s3 of the train load on the deformation of the karez, and obtaining the karez shaft and the underdrain under the train load at the distance of Scr without reinforcement; sigmaXmax，σYmaxMaximum horizontal and vertical dynamic stresses at the crossing location of the foundation; dy is the settlement of the surface of the foundation, and dymax is the maximum settlement; q is the deformation of the monitored karez at different positions, and the maximum deformation of the underdrain at the crossing center position is Qmax; the deformation of the shaft is measured by 10% of the shaft diameter (Sd);
When the following conditions are satisfied: sigmax<0.1σXmax、σy<0.1σYmax、dy<0.1dy max、Qy<0.1Qy maxAnd Qx<And when the Sd is 0.1Sd, determining that the Scr is a critical distance, and determining the influence range of the dynamic load, wherein the influence of the dynamic load on the karez is negligible outside the critical distance.
Compared with the prior art, the invention has the beneficial effects that:
1. the invention can effectively simulate the working condition of the high-speed railway roadbed crossing the karez under the working conditions of different karez intersection angles, burial depths and the like indoors, and obtain more accurate data through the test element; the collapse damage and deformation law of the underground canal of the karez, the influence of train load on the deformation of the karez, the influence of the underground canal on subgrade settlement, the attenuation law of dynamic stress in the foundation, the form evolution process of the soil arch effect of the karez and the like under different intersection angles can be researched in a targeted manner.
2. The method can comprehensively evaluate the interaction influence range of the inclined crossing karez of the high-speed railway roadbed according to the test result, determine the required processing area of the inclined crossing karez roadbed and the foundation, lay a good theoretical foundation for the construction of the high-speed railway roadbed in the actual karez area, and have simple and convenient test device and process, thereby being convenient to operate in a laboratory.
Drawings
Fig. 1 is a schematic structural diagram of a model test device of a high-speed railway roadbed crossing a karman obliquely.
Wherein, 1, a model box; 2. a model roadbed; 3. model foundation; 4. a well underdrain; 5. a karez shaft; 6. a reaction frame; 7. a loading device; 8. a displacement meter; 9. a strain gauge; 10. a soil pressure cell; 11. A water content meter; 12. and a loading plate.
Detailed Description
The following description of the embodiments of the present invention is provided to facilitate the understanding of the present invention by those skilled in the art, but it should be understood that the present invention is not limited to the scope of the embodiments, and it will be apparent to those skilled in the art that various changes may be made without departing from the spirit and scope of the invention as defined and defined in the appended claims, and all matters produced by the invention using the inventive concept are protected.
As shown in figure 1, the invention provides a model test device for a high-speed railway roadbed crossing a karez, which comprises a reaction frame 6, a model device, a loading device 7, a monitoring system and a data acquisition system.
The model device comprises a model box 1, wherein the model box 1 consists of a frame and transparent toughened glass arranged on the side wall of the frame, and the size of the model box is based on the condition that no boundary effect occurs.
A model roadbed 2 and a model foundation 3 arranged below the model roadbed 2 are arranged in the model box 1, and a karez underdrain 4 and a karez shaft 5 which are simulated by PVC pipes are arranged in the model foundation 3; for convenience of model test development, the test model size similarity ratio may be 20. According to the similarity ratio, the width of the surface layer of the foundation bed designed by the standard section is 8.2m, the width of the bottom surface of the embankment is 23.2m, the height is 5m, and the slope gradient is 1: 1.5, so that the width of the surface layer of the foundation bed of the corresponding model roadbed 2 is 41cm, the width of the bottom surface of the embankment is 116cm, and the height of the roadbed is 25 cm. The dimensions of the mold box 1 are as follows: the height of the model box 1 is the height of the foundation plus the height of the roadbed, and a certain safety space is reserved, so that the height of the model box 1 is 1.5m, and the width and the length of the model box 1 are the length of the ground base surface, namely 2 m. Therefore, the internal dimensions of the mold box 1 actually selected are 2.0m × 2.0m × 1.5m (length × width × height). In addition, the transparent tempered glass has a thickness of 30 mm. Most of the soil layers in the karez area are clay sand, and clay sand materials are used as a model roadbed 2 and a model foundation 3 in a model test.
The PVC pipe is selected to simulate the karez because the PVC pipe has high tensile strength, but can be damaged under high pressure, thereby conforming to the characteristic of the karez. A water bag with a remote switch valve is arranged in the PVC pipe, and the diameter of the PVC pipe and the water bag is 7.5cm to simulate a karez underdrain 4 or a vertical shaft 5 with a practical diameter of 1.5 m. When the model is filled, the water bag is adopted to fill the PVC pipe in advance so as to avoid the PVC pipe from being damaged before the model is formed. After the model is filled, the simulation of the canyon underdrain 4 is completed by draining water in the water bag with the remote switch valve opened.
The loading device 7 is connected with the reaction frame 6, and the loading device 7 is used for applying static load and dynamic load to the model roadbed 2; the loading device 7 is divided into a static loading device and a dynamic loading device. The static load device and the dynamic load device realize the application of static load and dynamic load to the model roadbed 2 through the loading plate 12, and a layer of concrete cushion layer is arranged below the loading plate 12 and used for enabling the load generated by the loading device 7 to be uniformly distributed on the roadbed. A buffer device is arranged between the model foundation 3 and the inner wall of the model box 1 and comprises a buffer cushion and a rigid baffle plate, the buffer cushion can be a foam plate, two side walls of the buffer cushion are respectively contacted with the side wall of the model foundation 3 and the side wall of the rigid baffle plate, the other side wall of the rigid baffle plate is contacted with the inner wall of the model box 1, flexible buffer materials such as the foam plate are firstly distributed on the soil edge of the foundation, and then the rigid baffle plate is arranged outside the flexible buffer materials to prevent the vibration exciter from damaging the test device in the loading applying process.
Preferably, but not limited to, the static load loading is to load the sample by using a jack, data is recorded once every 1min, and the loading is stopped when the load is slightly higher than the train load. The dynamic load loading adopts servo vibration exciter equipment, which consists of a hydraulic servo loading system and a loading actuator, wherein the size of the loading plate 12 is 2.0m multiplied by 0.3m multiplied by 0.03m (length multiplied by width multiplied by height), the maximum dynamic load loading value can reach 200kN, the highest dynamic load frequency can reach 100Hz, and the working condition of the high-speed railway roadbed under the dynamic load action can be fully simulated. And (3) carrying out loading on the sample in a sine cycle loading mode by using a vibration exciter, observing and recording data in each loading cycle, and stopping loading at the moment.
The monitoring system comprises a displacement meter 8 arranged on the surfaces of the model subgrade 2 and the model foundation 3, strain gauges 9 arranged on the surfaces of the canyon underdrain 4 and the canyon shaft 5, soil pressure boxes 10 arranged in the model subgrade 2 and the model foundation 3 and a water cut meter 11 arranged in the model foundation 3; the data acquisition system is electrically connected with the monitoring system, and the data acquisition system can adopt a computer.
The change rules of displacement, soil pressure and water content under the action of self weight and roadbed load are measured by using sensors such as a displacement meter 8, a strain gauge 9, a soil pressure box 10 and a water content meter 11, a static data acquisition instrument and a corresponding test analysis system.
The invention also provides a test method of the model test device of the high-speed railway roadbed of the inclined crossing karez, which comprises the following steps:
s1: model size calculation
Setting a model test similarity ratio by taking the non-occurrence boundary effect as a reference, and calculating the sizes of a model roadbed 2, a model foundation 3 and a PVC pipe filled in a model box 1 and the quality of required filling according to the similarity ratio; in order to research the influence of the intersection angle between the underdrain and the roadbed load central line on the stability of the roadbed structure, the underdrain can be arranged at different angles of 0-90 degrees and the like; in order to research the influence of the buried depth of the underdrain on the stability of the roadbed structure, the depth H from the underdrain to the upper foundation can be 3-7 times of the diameter of the underdrain; the distance between the underdrain and the load center on the cross section can be determined according to the actual requirement of the simulated work point underdrain.
S2: filling sample
Adopting a shakeout method for layered filling, leveling and compacting each layer of similar material after filling, ensuring that the dry density of each layer of soil is the same in the filling process, specifically, performing primary leveling after filling each layer of similar material, paving a wood board on the surface of the soil body after leveling, compacting the filled similar material by using a weight with fixed mass through the force transfer action of the wood board, ensuring that the hammering times of each layer of sand are the same, and adjusting the height difference by using a horizontal ruler again after compacting to keep the surface of the filled soil flat; placing the PVC pipe into the model foundation 3 to simulate a karez underdrain 4 or a vertical shaft 5 under the designed buried depth; a water sac is placed in a PVC pipeline of the simulated camphannels underdrain 4 in advance, and after the model foundation 3 is filled, the water sac is drained to obtain the simulated camphannels underdrain 4 without supporting holes;
S3: arrangement monitoring system
Burying soil pressure boxes 10 and water content meters 11 in the model subgrade 2 and the model foundation 3, mounting strain meters 9 on PVC pipelines, and mounting displacement meters 8 on the surfaces of the model subgrade 2 and the model foundation 3; the soil pressure cell 10, the moisture content meter 11, the strain gauge 9 and the displacement meter 8 are electrically connected with a data acquisition system; the data acquisition system tests whether the reading of the monitoring system is normal, if so, the step 4 is carried out, otherwise, the data acquisition system is checked until the reading is normal;
s4: arranging a loading device 7
Placing the loading part on a cement base plate to ensure that the load generated by the loading device 7 is uniformly distributed on the roadbed, wherein the thickness of the base plate is preferably 50 mm;
s5: dead load loading
Loading the sample by a jack, wherein the loading rate is not too fast, recording data once at intervals of 1min, stopping loading when the jack is loaded to be higher than the load of the train, and recording and arranging the data;
s6: dynamic load loading
The vibration exciter loads a sample in a sine wave form with the amplitude of 5kN and the frequency of 10Hz, is used for simulating the load of a high-speed train, observes and records the data of a monitoring system, and stops loading the sample until a PVC pipe is damaged or the power cycle frequency reaches 10000 times;
s7: unloading; safety needs to be paid attention, and the unloading should be carried out after the switch of the loading device 7 is turned off;
S8: and analyzing and determining the interaction of the karez to the high-speed railway roadbed according to the physical parameters acquired by the monitoring system.
Step S8 further includes: after the test is finished, the data of the soil pressure cell 10 obtains the soil pressure distribution in the structures of the model subgrade 2 and the model subgrade 3 in the dynamic load stage, so that the attenuation rules of dynamic stress in the horizontal direction and the vertical direction are further obtained, and the influence distribution and the action range of high-speed railway load on the subgrade are obtained;
the settlement of the model subgrade 2 and the model subgrade 3 in the dynamic load stage is obtained according to the displacement parameters collected by the displacement meter 8, and the influence of the existence of the karez on the subgrade settlement is obtained;
obtaining the strain quantities of the campshed covered channel 4 and the campshed vertical shaft 5 in the dynamic load stage according to the strain parameters collected by the strain gauge 9, and obtaining the influence of the train load on the deformation of the campshed; the model test results are used to evaluate the influence range of the high-speed railway subgrade inclination crossing the karez interaction.
Further, the method for determining the influence range of the high-speed railway subgrade inclined across the karez interaction according to the model test result comprises the following steps:
analyzing attenuation laws sigma x and sigma y of the dynamic stress in the horizontal direction and the vertical direction to obtain an influence range s1 of the high-speed rail load; analyzing the settlement d of the karez foundation under dynamic load to obtain the influence s2 of the karez on the settlement of the foundation; analyzing the deformation Qy of the karez and the deformation Qx of the shaft at different positions under the dynamic load to obtain the influence s3 of the train load on the deformation of the karez, and obtaining the karez shaft and the underdrain under the train load at the distance of Scr without reinforcement; sigma Xmax，σYmaxMaximum horizontal and vertical dynamic stresses at the crossing location of the foundation; dy is the settlement of the surface of the foundation, and dymax is the maximum settlement; q is deformation of the karez at different positions to be monitored, cross centerThe maximum deformation amount of the underdrain at the position is Qmax; the deformation of the shaft is measured by 10% of the shaft diameter (Sd);
when the following conditions are satisfied: sigmax<0.1σXmax、σy<0.1σYmax、dy<0.1dy max、Qy<0.1Qy maxAnd Qx<And when the Sd is 0.1Sd, determining that the Scr is a critical distance, and determining the influence range of the dynamic load, wherein the influence of the dynamic load on the karez is negligible outside the critical distance.
In conclusion, the working condition of the high-speed railway roadbed crossing the karez can be effectively simulated indoors under working conditions of different karez intersection angles, burial depths and the like, and more accurate data can be obtained through the test element; the collapse damage and deformation rule of the underground canal 4 of the karez, the influence of train load on the deformation of the karez, the influence of the underground canal on subgrade settlement, the attenuation rule of dynamic stress in a foundation, the form evolution process of the soil arch effect of the karez and the like can be researched in a targeted manner under different intersection angles, the influence range of the high-speed railway subgrade inclining and crossing the karez interaction can be comprehensively evaluated by combining test results, the required processing area of the inclining and crossing karez subgrade and the foundation can be determined, a good theoretical foundation is laid for the high-speed railway subgrade construction in the actual karez area, and the test device and the test process are simple and convenient to operate in a laboratory.
Claims (10)
1. The model test device of the high-speed railway roadbed of the obliquely crossing karez is characterized by comprising a reaction frame, a model device, a loading device, a monitoring system and a data acquisition system;
the model device comprises a model box, wherein a model subgrade and a model foundation arranged below the model subgrade are arranged in the model box, and a karez underdrain and a karez shaft which are simulated by adopting PVC pipes are arranged in the model foundation; the intersection angle theta of the karez underdrain and the line is 0-90 degrees, and collapse damage and deformation rules of the karez underdrain are obtained under different intersection angles theta;
the loading device is connected with the reaction frame and is used for applying static load and dynamic load to the model roadbed;
the monitoring system comprises displacement meters arranged on the surfaces of the model roadbed and the model foundation, strain gauges arranged on the surfaces of the karez underdrain and the karez shaft, soil pressure boxes arranged in the model roadbed and the model foundation and a water content meter arranged in the model foundation; the data acquisition system is electrically connected with the monitoring system.
2. The model test device of the high-speed railway subgrade of the obliquely crossing karez according to the claim 1, characterized in that the model box comprises a frame made of section steel and transparent toughened glass arranged on the side wall of the frame; the inside dimension of the mold box is 2.0m × 2.0m × 1.5m, and the thickness of the transparent tempered glass is 30 mm.
3. The model test device of a high speed railway roadbed in a slant span karez according to claim 2, wherein the material of the model roadbed and the model foundation is clay sand.
4. The model test device for the high-speed railway subgrade of the slant candela well according to claim 3, wherein the loading device comprises a jack for applying a static load to the model subgrade and a servo vibration exciter for applying a dynamic load to the model subgrade, the servo vibration exciter is used for simulating the dynamic load applied to the model subgrade by the high-speed railway train, the dynamic load frequency of the servo vibration exciter is 5Hz, and the dynamic load dynamic stress amplitude is 10 kN.
5. The model test device for the roadbed of the high-speed railway crossing the karez according to claim 4, wherein the loading device further comprises a loading plate, the lower surface of the loading plate is provided with a concrete cushion layer, and the jack and the servo vibration exciter apply static load and dynamic load to the model roadbed through the loading plate.
6. The model test device of the high-speed railway subgrade of the inclined crossing karez as claimed in claim 1, characterized in that water bags with remote switch valves are arranged in the karez underdrain and the karez shaft.
7. The model test device for the roadbed of the high-speed railway crossing the karez according to claim 4, wherein a buffer device is arranged between the model foundation and the inner wall of the model box, the buffer device comprises a buffer pad and a rigid baffle plate, two side walls of the buffer pad are respectively contacted with a side wall of the model foundation and a side wall of the rigid baffle plate, and the other side wall of the rigid baffle plate is contacted with the inner wall of the model box.
8. A test method of the model test device of the high-speed railway roadbed of the inclined crossing karez according to the claims 1-7, characterized by comprising the following steps:
s1: model size calculation
Setting a model test similarity ratio by taking the non-occurrence boundary effect as a reference, and calculating the sizes of a model roadbed filled in the model box, a model foundation and a PVC pipe and the quality of required filled soil according to the similarity ratio;
s2: filling sample
Adopting a shakeout method for layered filling, and leveling and compacting each layer of similar material after filling is finished to ensure that the dry density of each layer of soil is the same in the filling process; under the designed buried depth, a PVC pipeline is placed into a model foundation to simulate a trunk underdrain or a vertical shaft, the intersection angle between the trunk underdrain and a line is theta, and the intersection angle theta is 0-90 degrees; a water sac is placed in a PVC pipeline of the simulated camphannels underdrain in advance, and after filling of the model foundation is completed, the water sac is drained to obtain the simulated camphannels underdrain without supporting holes;
s3: arrangement monitoring system
Burying a soil pressure box and a water content meter in the model roadbed and the model foundation, mounting a strain meter on a PVC pipeline, and mounting a displacement meter on the surface of the model roadbed and the model foundation; electrically connecting the soil pressure cell, the water content meter, the strain gauge and the displacement meter with a data acquisition system; the data acquisition system tests whether the reading of the monitoring system is normal, if so, the step 4 is carried out, otherwise, the data acquisition system is checked until the reading is normal;
S4: placement loading device
The loading device is connected with the reaction frame, and a concrete cushion layer is arranged on the loading plate;
s5: dead load loading
Loading the sample by a jack, recording data once at intervals of 1min, stopping loading when the jack is loaded to be higher than the load of the train, and recording and arranging the data;
s6: dynamic load loading
The vibration exciter loads a sample in a sine wave form with the amplitude of 5kN and the frequency of 10Hz, is used for simulating the load of a high-speed train, observes and records the data of a monitoring system, and stops loading the sample until a PVC pipe is damaged or the power cycle frequency reaches 10000 times;
s7: unloading;
s8: and analyzing and determining the interaction between the karez and the high-speed railway roadbed according to the data collected by the monitoring system.
9. The method for testing the model test device of the high-speed railway roadbed in the obliquely crossing karez according to the claim 8, wherein the step S8 further comprises:
the data of the soil pressure cell is used for obtaining the soil pressure distribution in the model subgrade and the model foundation structure in the dynamic load stage, further obtaining the attenuation law of dynamic stress in the horizontal direction and the vertical direction, and obtaining the influence distribution and the action range of high-speed railway load on the subgrade;
Obtaining settlement of the model subgrade and the model foundation in the dynamic load stage according to the displacement parameters acquired by the displacement meter, and obtaining the influence of the existence of the karez on the subgrade settlement;
obtaining the strain quantities of the hidden channel and the vertical shaft of the karez in the dynamic load stage according to the strain parameters collected by the strain gauge, and obtaining the influence of the train load on the deformation of the karez; the model test results are used to evaluate the influence range of the high-speed railway subgrade inclination crossing the karez interaction.
10. The method for testing the model test device of the high-speed railway subgrade crossing the karman according to the claim 9, characterized in that the method for determining the influence range of the high-speed railway subgrade crossing the karman interaction obliquely according to the model test result comprises the following steps:
analyzing attenuation laws sigma x and sigma y of the dynamic stress in the horizontal direction and the vertical direction to obtain an influence range s1 of the high-speed rail load; analyzing the settlement d of the karez foundation under dynamic load to obtain the influence s2 of the karez on the settlement of the foundation; analyzing the deformation Qy of the karez and the deformation Qx of the shaft at different positions under the dynamic load to obtain the influence s3 of the train load on the deformation of the karez, and obtaining the karez shaft and the underdrain under the train load at the distance of Scr without reinforcement; sigma Xmax，σYmaxMaximum horizontal and vertical dynamic stresses at the crossing location of the foundation; dy is the settlement of the surface of the foundation, and dymax is the maximum settlement; q is the deformation of the monitored karez at different positions, and the maximum deformation of the underdrain at the crossing center position is Qmax; the deformation of the shaft is measured by 10% of the shaft diameter (Sd);
when the following conditions are satisfied: sigmax<0.1σXmax、σy<0.1σYmax、dy<0.1dy max、Qy<0.1Qy maxAnd Qx<And when the Sd is 0.1Sd, determining that the Scr is a critical distance, and determining the influence range of the dynamic load, wherein the influence of the dynamic load on the karez is negligible outside the critical distance.
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| CN117150817B (en) * | 2023-10-26 | 2024-02-02 | 湖南大学 | Combined door type anti-floating frame design method based on soil arch effect |
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