CN111157363B - Earth pressure balance shield muck workability and improvement optimization evaluation test method - Google Patents
Earth pressure balance shield muck workability and improvement optimization evaluation test method Download PDFInfo
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Abstract
The invention provides a test method for soil pressure balance shield muck workability and improvement optimization evaluation, wherein a test system comprises a horizontally arranged test cylinder, an axial loading device for simulating a shield machine jacking mechanism, a radial extrusion ring bag for simulating a spiral conveyor dumping mechanism, a water supply system for applying different water pressures, a shearing rod for collecting soil sample strength, a test bin pressure sensor for collecting pore water pressure and the like. The test method comprises the step of comprehensively testing the workability of the soil sample under the simulated working condition that any one of the soil discharging speed and the pushing pressure is changed or the soil discharging speed and the pushing pressure are synchronously changed under the condition of controlling different water pressures. Wherein, the workability test of the soil sample comprises any one or more of permeability, strength and deformation characteristics. The data measured by the test system and the test method of the invention is more scientific and objective, has certain automatic control intellectualization, and is particularly suitable for the research of the soil pressure balance shield muck workability related test under the special working conditions of simulating rich water and the like.
Description
Technical Field
The invention relates to shield tunnel working condition simulation experiment equipment, in particular to a soil pressure balance shield muck workability and improvement optimization evaluation test method.
Background
The method is characterized in that the test on the workability of the muck in the bin in the construction of the earth pressure balance shield has important influence on the safe and rapid tunneling of the shield, and different mucks are generally required to be improved and optimized to achieve the ideal workability. The workability of the muck (including the muck before modification and the muck after modification) mainly comprises three aspects of strength, deformation and permeability: the test chamber has the advantages of reducing the abrasion of a cutter head and a cutter, controlling the formation of mud cakes, meeting the requirements of pressure maintaining balance of a test chamber, achieving ideal flow plasticity and the like by virtue of low strength, moderate compression deformation characteristic and low permeability. However, the above three aspects usually cannot achieve optimization consistency, and in actual engineering, the purpose of achieving optimization results is to keep the three aspects of workability in a coordinated balance. How to scientifically test and evaluate the workability of the muck and improve the optimization effect is particularly important for safe and efficient construction of the shield and related scientific research, wherein the research and development of a reasonable test and evaluation test system and method become key points.
The existing test equipment and test method for the workability of the muck and the improved body have some defects in different degrees: firstly, a direct shear apparatus, a triaxial apparatus and a lateral confinement compression apparatus are mainly used for testing the strength and the deformation characteristics, but for muck, the flow plasticity of the modifier is enhanced after a certain amount of the modifier is added, so that a plastic sample for the equipment test is difficult to form; the size specification of the equipment for testing the strength and deformation characteristic parameters is relatively small, and the equipment is difficult to adapt to the test research of the existing coarse-particle wide-grade muck soil sample in the shield engineering; the existing soil body permeability test equipment mainly tests the permeability of the muck under a constant head or a variable head, but for water-rich strata such as a downward river, a seabed stratum and the like, the existing soil body permeability test equipment usually faces high water-rich pressure of hundreds of kilopascals; meanwhile, the mutual coupling effect of water pressure and soil pressure in a shield machine test bin in a water-rich stratum influences the working performance of the muck, the existing permeation equipment generally cannot apply the soil pressure to the muck during a permeation test, the coupling influence between the muck and the existing permeation equipment is neglected in the test method, and the working performance of the obtained muck loses certain objectivity; the shield soil bin muck is influenced by multi-field coupling of a cutter head mechanism, an axial pushing mechanism, a soil discharging mechanism, an underground water environment and the like, the workability of the shield soil bin muck is in a dynamic process of random change, the existing test method mainly tests the workability of the muck by a single field or simplified means, and the obtained result has certain limitation in practical engineering application. Furthermore, the existing muck workability test mainly adopts three independent tests, and is difficult to synchronously test to obtain three indexes of strength, deformation and permeability, so that the workload of the test is increased rapidly, and a certain test error is generated due to the instability of muck sample preparation. In conclusion, the most effective way for solving the problems is undoubtedly to develop and design a comprehensive test and evaluation test system which can be used for synchronously testing the muck workability and improving the optimization effect evaluation under the conditions of normal high soil and water pressure, and to provide a muck workability test method which is suitable for simulating different construction working conditions of the shield and considers multi-field linkage change.
Disclosure of Invention
The invention aims to provide a test method for soil pressure balance shield muck workability and improvement optimization evaluation, and aims to solve the problems in the background art.
A soil pressure balance shield muck workability and improvement optimization evaluation test method is characterized in that a soil pressure balance shield muck workability and improvement optimization evaluation test system is adopted to simulate the working condition of a shield machine, the workability of a soil sample is tested and evaluated in the simulated working condition, and the soil pressure balance shield muck workability and improvement optimization evaluation test system comprises a test cylinder, a fixed plate, a movable plate, a first water permeable cushion, a second water permeable cushion, a shearing rod, a shearing transmission rod, an axial loading device, an axial displacement sensor, a radial extrusion ring bag and test bin pressure sensor, a first water tank, a first switch valve, a water pressure regulating valve, a second air pressure regulating valve, a flow control valve and a control terminal;
the axial direction of the test cylinder is arranged along the horizontal direction, a test chamber is arranged in the test cylinder, the left end of the shaft of the test cylinder is sealed by a sealing plate, the axial right end of the test cylinder is provided with an opening, the right end opening is sealed by a detachable end cover, the fixed plate and the movable plate are both provided with water permeable holes, the plate surfaces of the fixed plate and the movable plate are both arranged along the vertical direction, the fixed plate is fixed at the left end in the test cylinder, a first interval for forming a left containing cavity is kept between the fixed plate and the sealing plate of the test cylinder along the axial direction of the test cylinder, the movable plate is movably arranged at the right end in the test cylinder, a second interval for forming the test chamber is kept between the fixed plate and the movable plate along the axial direction of the test cylinder, a third interval for forming a right containing cavity is kept between the movable plate and the end cover of the test, the second water permeable cushion is used for being arranged between the movable plate and the soil sample in the test bin in a spaced mode;
a water inlet used for being connected with a water supply system is formed in the position, corresponding to the top of the left containing cavity, of the cylinder wall of the test cylinder, a water outlet is formed in the position, corresponding to the bottom of the right containing cavity, of the cylinder wall of the test cylinder, a valve capable of being opened or closed is arranged in the position, corresponding to the top of the right containing cavity, of the cylinder wall of the test cylinder, and the valve can be used as an air outlet or a;
the left end of the shearing transmission rod is positioned in the test bin, the shearing rod is connected to the left end of the shearing transmission rod, the right end of the shearing transmission rod sequentially penetrates through the second water permeable cushion, the movable plate and the through holes formed in the end cover from left to right, extends out of the test cylinder and is connected with the shearing transmission mechanism, and the shearing transmission mechanism is provided with a torque sensor; the torque sensor is used for testing the shear strength tau of different soil samples under different simulation working conditions;
the axial loading device comprises a pressurizing cylinder which is arranged between an end cover and a movable plate in an abutting mode along the axial direction of the test cylinder, and the axial displacement sensor is connected between the movable plate and the end cover or between the movable plate and a pressurizing cylinder body or between a pressurizing cylinder piston rod and a pressurizing cylinder body; the axial displacement sensor is used for measuring the length change x of the soil sample along the axial direction of the test cylinder so as to test the deformation characteristic of the soil sample;
the loading force of the axial loading device is used for simulating the jacking force applied to the soil bin by an axial jacking mechanism (namely a jack) of the shield tunneling machine;
the water inlet of the test cylinder is connected with the first water tank through a water inlet pipeline, the first switch valve and the hydraulic pressure regulating valve used for regulating the water inlet pressure of the test chamber are arranged on the water inlet pipeline, and the air inlet pipeline of the pressurizing cylinder is connected with the second air pressure regulating valve used for regulating the air inlet pressure of the pressurizing cylinder.
The radial extrusion ring bag is arranged in the test bin and is positioned at the periphery of the soil sample, a fluid pressure medium is filled in the radial extrusion ring bag, the outer wall of the radial extrusion ring bag is attached to the inner wall of the test bin under the pressure action of the fluid pressure medium, the inner wall of the radial extrusion ring bag is used for applying radial extrusion force to the soil sample, and the volume and the thickness of the radial extrusion ring bag can be changed along with the change of the flow of the charged fluid, so that the volume of the soil sample is changed and/or the length of the soil sample along the axial direction of the test tube is changed, and the radial extrusion ring bag is used for simulating different soil discharge speeds of a spiral conveying mechanism of the shield machine;
the fluid conveying pipeline of the radial extrusion ring bag is provided with the flow control valve for controlling the flow of fluid pressure medium entering the radial extrusion ring bag;
the water pressure regulating valve, the air pressure regulating valve II and the flow control valve are electrically connected with the control terminal, and the control terminal is used for synchronously regulating the electric signals of the water pressure regulating valve, the air pressure regulating valve II and the flow control valve so as to enable the soil sample in the test bin to be applied with synchronously changed water inlet pressure, axial loading force and radial extrusion force, namely, the synchronous change of the soil pressure and the water pressure is realized;
the test bin pressure sensors are arranged on the inner wall of the radial extrusion annular bag and are arranged at intervals along the axial direction of the test cylinder; the test bin pressure sensor is used for monitoring the pore water pressure of the soil sample in the test bin under different jacking forces and different soil discharge speeds, and further used for calculating the effective stress sigma' of the soil sample in the test bin by combining the loading force P of the pressurizing cylinder;
the axial displacement sensor, the test bin pressure sensors and the torque sensor are all connected with the control terminal, and the control terminal is used for receiving real-time data of displacement, hole pressure and torque measured by the axial displacement sensor, the test bin pressure sensors and the torque sensor so as to facilitate subsequent calculation of soil sample parameters;
the soil pressure balance shield muck workability evaluation test method comprises the following steps of testing the workability of a soil sample in any one of the following three simulation working conditions:
the method comprises the following steps of simulating a first working condition, controlling the volume of fluid pressure medium in a radial extrusion ring bag to be unchanged, changing the air inlet pressure of a pressurizing air cylinder of an axial loading device, simulating an axial pushing mechanism to apply different pushing forces to a soil bin of the shield tunneling machine, and testing the workability of a soil sample under the simulated working condition;
simulating a working condition II, keeping the air inlet pressure of a pressurizing air cylinder of the axial loading device unchanged, changing the volume of a fluid pressure medium in the radial extrusion ring bag, simulating the change of the soil discharging speed of a spiral conveying mechanism of the shield tunneling machine, and testing the workability of the soil sample under the simulated working condition;
simulating a working condition III, enabling the air inlet pressure of a pressurizing air cylinder of the axial loading device and the volume of the fluid pressure medium in the radial extrusion ring bag to synchronously change, simulating the synchronous change of the jacking force of the shield tunneling machine and the soil discharging speed of the spiral conveying mechanism, and testing the workability of the soil sample under the simulated working condition;
further, in three simulated working condition tests in the soil pressure balance shield muck workability evaluation test method, the water supply system is synchronously controlled to apply water pressures with different pressures to the soil sample of the test cylinder so as to simulate and test the soil sample workability under different underground water-rich conditions and special working conditions of the river-sea.
The workability test of the soil sample comprises any one or more of the permeability of the soil sample, the shear strength tau of the soil sample and the deformation characteristic of the soil sample;
the soil pressure balance shield muck workability and improvement optimization evaluation test method further comprises the steps of applying water flows with different pressures to the soil sample in the test bin in the three simulation working conditions, namely applying different water pressures, synchronously testing the permeability characteristic of the soil sample and applying the permeability characteristic to the calculation of effective stress sigma' and effective strength parameters so as to objectively and scientifically simulate and test the workability of the soil sample under different underground water-rich conditions or the working conditions of high water pressure of the ground layer under river crossing and seabed, and particularly can simulate the working change condition of the soil sample in the shield penetration and gushing dynamic process;
the shear strength tau of the soil sample is calculated by adopting formula 1:
the shearing device comprises a shearing rod, a torque sensor, a transmission mechanism, a shearing rod, a driving mechanism and a driving mechanism, wherein M is the torque which is measured by the torque sensor and applied to the shearing transmission rod by the transmission mechanism, a is the transverse size of the shearing rod, theta is an included angle between the shearing rod and the shearing transmission rod, H is the sine value of the length of the shearing rod multiplied by the angle theta, and L is the cosine value of the length of the shearing rod;
the permeability test of the soil sample comprises the step of calculating the permeability coefficient K of the soil sample by adopting the formula 2T：
Where ρ iswIs the density of water, t is the permeation time, Q is the amount of water permeated within the time t, and g is the acceleration of gravity;
the effective stress σ' of the soil sample is calculated using equation 3:
wherein m is the number of the pressurizing cylinders, d is the inner diameter of the test chamber, and h0Is the axial initial length size of the soil sample before loading, x is the length variation of the soil sample along the axial direction of the test cylinder, QhThe water filling volume of the annular bag is radially extruded, S is the distance between two adjacent test chamber pressure sensors along the axial direction of the test cylinder, and n is that of the test chamber pressure sensorNumber or group number, P'nPore water pressure measured by the pressure sensor of the nth test bin;
the first polynomial on the right side of the equation shown in the formula 3 is the loading force of the axial loading device, and the second polynomial is the seepage force suffered by the soil sample;
the deformation characteristic test of the soil sample comprises the steps of calculating the porosity E of the soil sample by adopting a formula 4 and calculating the compression modulus E of the soil sample by adopting a formula 50：
Wherein w is the moisture content of the muck sample before improvement, m is the quality of the muck sample before improvement, rhosThe particle density of the residue soil sample before improvement.
The plurality of test bin pressure sensors are arranged at the positions of the horizontal quadrant points of the inner wall of the test bin, which are positioned in the same horizontal plane with the shearing transmission rod. The pressure sensor of the test chamber mainly has the function of obtaining the hydraulic slope in the horizontal direction in the test chamber, so that the derivation calculation of the permeability and the permeability coefficient in the horizontal direction is carried out, and the effective stress can be calculated through the calculated permeability.
Furthermore, the pressurizing air cylinders are m in central symmetry type structure distribution on the radial periphery of the shearing transmission rod, m is an integer larger than or equal to 2, piston rods of the pressurizing air cylinders are located at one end of the movable plate, cylinder bodies of the pressurizing air cylinders are fixed with the end covers, end walls of one ends of rodless cavities of the cylinder bodies of the pressurizing air cylinders are integrally arranged with the end covers, namely the end walls of one ends of the rodless cavities of the cylinder bodies of the pressurizing air cylinders are a part of the end covers, and air inlet pipelines of the cylinder bodies of the pressurizing air cylinders directly penetrate through the end covers and are led into the rodless.
Further, the soil pressure balance shield muck workability and improvement optimization evaluation test system further comprises a motor, an air compressor, an air storage tank, a first air path, a first air pressure regulating valve, a second air path, a third air path and a third air pressure regulating valve, wherein the motor is used for connecting and driving the air compressor, an inlet of the air storage tank is connected with an outlet of the air compressor, the air storage tank is used for storing pressure gas serving as a pressure gas source, one ends of the first air path, the second air path and the third air path are connected in parallel to an outlet of the air storage tank, the other end of the first air path is used for connecting a water inlet pipeline of a test tube, the other end of the second air path is used for connecting a pressurizing cylinder of an axial loading device, namely serving as an air inlet pipeline of the pressurizing cylinder, and the other end of the third air path is connected with the radial extrusion ring bag to provide pressure required by, the first air pressure regulating valve is arranged on the first air path, the second air pressure regulating valve is arranged on the second air path, the third air pressure regulating valve is arranged on the third air path, the first air pressure regulating valve is used for regulating the water supply pressure of the water tank, the second air pressure regulating valve is used for regulating the air inlet pressure of the pressurizing air cylinder of the axial loading device, and the third air pressure regulating valve is used for regulating the fluid filling pressure of the radial extrusion annular bag.
Further, the fluid pressure medium in the radial extrusion ring bag is water, the soil pressure balance shield muck workability and improvement optimization evaluation test system also comprises a water tank II, the flow control valve comprises a switch valve II and an electromagnetic proportional flow valve, the water outlet of the water tank II is connected with the radial extrusion annular bag, the second switch valve and the electromagnetic proportional flow valve are arranged on a connecting pipeline between the second water tank and the radial extrusion annular bag, the electromagnetic proportional flow valve is used for controlling the flow of water filled in the radial extrusion annular bag to adjust the volume of the radial extrusion annular bag, thereby changing the radial extrusion force, when the water quantity filled in the radial extrusion ring bag reaches a certain set value, and the water is stopped from being filled into the radial extrusion annular bag through the second switch valve, so that the volume of the radial extrusion annular bag is kept at a certain fixed value, and the other end of the third air passage is connected with the inlet of the second water tank.
Further, the soil pressure balance shield muck workability and improvement optimization evaluation test system further comprises a modifier adding system, the modifier adding system comprises a modifier generating device and a modifier conveying pipeline, the inlet end of the modifier conveying pipeline is connected with the modifier generating device, the outlet end of the modifier conveying pipeline penetrates through the side wall of the test barrel and then extends into the test bin or sequentially penetrates through the end cover and the movable plate and then extends into the test bin, the modifier conveying pipeline is used for injecting a modifier into the test bin filled with muck, and the shearing rod is further used for stirring and mixing the muck and the modifier in the test bin.
The soil pressure balance shield muck workability and improvement optimization evaluation test method further comprises the steps of adding a modifier to the same soil sample through a modifier adding system after the workability test of the same soil sample in any one of the simulation working conditions is finished, carrying out improvement optimization, and carrying out any one of the simulation working condition tests on the improved soil sample to obtain the workability change test data before and after the improvement of the same soil sample for evaluation comparison of the improvement method.
Further, the hydraulic pressure regulating valve, the first air pressure regulating valve, the second air pressure regulating valve and the third air pressure regulating valve all adopt electromagnetic proportional pressure reducing valves, the first switch valve and the second switch valve all adopt electromagnetic switch valves, the earth pressure balance shield muck workability and improvement optimization evaluation test system further comprises a control terminal, the axial displacement sensor, the pressure sensors of all test bins and the torque sensor are all connected with the control terminal, the hydraulic pressure regulating valve, the first air pressure regulating valve, the second air pressure regulating valve, the third air pressure regulating valve and the first switch valve are all controlled by the control terminal through electric connection, and the second switch valve and the electromagnetic proportional flow valve are also controlled by the control terminal through electric connection.
The invention has at least the following beneficial effects:
the invention provides an earth pressure balance shield muck workability and improvement optimization evaluation test method.
The axial loading device is arranged for simulating different jacking forces applied to the soil bin by the axial jacking mechanism of the soil pressure balance shield machine, and different axial soil pressures are transmitted to the soil sample through the different axial jacking forces.
The test method provided by the invention is used for simulating the working condition when any one of the soil discharging speed and the axial jacking force changes or a plurality of working conditions change simultaneously, testing the workability of the soil sample, comparing the simulation of the working condition when any one of the soil discharging speed and the axial jacking force changes with the simulation of the working condition when the working conditions change simultaneously, and facilitating the research on the coupling influence of the soil discharging speed and the axial jacking force of the soil pressure balance shield machine on the workability of the muck.
The water supply system can apply stable water flows with different water pressures according to test requirements in a working condition test when any one of the simulated soil discharge speed and the axial jacking force is changed or a plurality of working conditions are changed simultaneously, so that the aim of researching the coupling influence characteristics of the soil sample workability under the linkage change of the water pressure and the soil pressure is fulfilled, and the technical problem of the shield soil warehouse muck workability simulation test of the water-rich high-water-pressure stratum is solved.
The testing method provided by the invention is used for testing the workability of the soil sample under the simulation working condition that any one of the soil discharging speed and the pushing pressure is changed or the soil discharging speed and the pushing pressure are synchronously changed, wherein the testing of the workability of the soil sample comprises any one or more tests of the permeability of the soil sample, the shear strength tau of the soil sample and the deformation characteristic of the soil sample. Because the data measured by the test system of the invention is more objective, the parameters obtained by the test method of the invention are closer to the reality.
The test method provided by the invention also measures and calculates the porosity e of the soil sample, and the porosity e can be used for researching the real-time change relationship between the permeability and the porosity of the muck because the permeability of the muck is related to the porosity of the muck. In the prior art, the change of the porosity of the muck in the infiltration process is mostly not considered, the method is basically suitable under the condition of not applying soil pressure, but the method is very important for measuring and calculating the porosity of the soil sample when the soil sample deforms due to the soil pressure.
In the invention, the test bin is connected with the modifier conveying pipeline, and as the modifier (foaming agent) is quickly attenuated after being mixed with the muck, the modifier is filled in the test bin after the soil sample is filled, so that more time can be won for the subsequent workability test of the soil sample, and the test result is more accurate.
In addition to the objects, features and advantages described above, other objects, features and advantages of the present invention are also provided. The present invention will be described in further detail below with reference to the drawings.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:
FIG. 1 is an overall schematic diagram of an earth pressure balance shield muck workability and improvement optimization evaluation test system according to a preferred embodiment of the invention;
FIG. 2 is a schematic cross-sectional view of a test cylinder of an earth pressure balance shield muck workability and improvement optimization evaluation test system according to a preferred embodiment of the present invention;
fig. 3 is a perspective view (rear view direction) of a test tube with an internal structure of an earth pressure balance shield muck workability and improvement optimization evaluation test system in a preferred embodiment of the present invention, which is turned to a vertical position;
FIG. 4 is a shear bar structure diagram of an earth pressure balance shield muck workability and improvement optimization evaluation test system according to a preferred embodiment of the present invention;
fig. 5 is a soil body shear strength parameter derivation schematic diagram of the soil pressure balance shield muck workability and improvement optimization evaluation test method according to the preferred embodiment of the invention.
In the figure: 1-test cylinder, 11-closing plate, 12-end cover, 13-water permeable hole, 14-left chamber, 15-test bin, 16-right chamber, 17-water inlet, 18-water outlet, 19-valve, 21-fixing plate, 22-movable plate, 23-first water permeable cushion, 24-second water permeable cushion, 25-turning device, 26-support frame, 260-concave support surface, 27-support leg, 31-motor, 32-air compressor, 33-air storage tank, 34-first air circuit, 35-first air pressure regulating valve, 36-second air circuit, 37-second air pressure regulating valve, 38-third air circuit, 39-third air pressure regulating valve, 4-shearing rod, 41-shearing transmission rod, 42-torque sensor, 5-axial loading device, 51-pressurizing cylinder, 32-axial displacement sensor, 6-radial extrusion annular bag, 60-test bin pressure sensor, 61-transverse sensor, 62-vertical sensor, 71-modifier generating device, 72-modifier conveying pipeline, 73-outlet end, 81-water tank I, 810-main box body, 811-water level monitoring pipe, 82-switch valve I, 83-water pressure regulating valve, 84-water tank II, 85-switch valve II, 86-electromagnetic proportional flow valve and 9-control terminal.
Detailed Description
Embodiments of the invention will be described in detail below with reference to the drawings, but the invention can be implemented in many different ways, which are defined and covered by the claims.
Referring to fig. 1-4, an earth pressure balance shield muck workability and improvement optimization evaluation test system comprises a water supply system, a test cylinder 1, a fixed plate 21, a movable plate 22, a permeable pad one 23, a permeable pad two 24, a shear rod 4, a shear transmission rod 41, an axial loading device 5, an axial displacement sensor 32, a radial extrusion ring capsule 6 and a test bin pressure sensor 60;
the axial direction of the test cylinder is arranged along the horizontal direction, the left end of the test cylinder is sealed by a sealing plate 11, the axial right end of the test cylinder is provided with an opening, the right end opening is sealed by an end cover 12, the end cover can be detached from the right end opening, the fixed plate and the movable plate are both provided with water permeable holes 13, the plate surfaces of the fixed plate and the movable plate are both arranged along the vertical direction, the fixed plate is fixed at the left end in the test cylinder, a first interval for forming a left containing cavity 14 is kept between the fixed plate and the sealing plate of the test cylinder along the axial direction of the test cylinder, the movable plate is movably arranged at the right end in the test cylinder, a second interval for forming a test bin 15 is kept between the fixed plate and the movable plate along the axial direction of the test cylinder, a third interval for forming a right containing cavity 16 is kept between the movable plate and the end cover of the, the second water permeable cushion is used for being arranged between the movable plate and the soil sample in the test bin in a spaced mode;
a water inlet 17 for connecting a water supply system is arranged at the position, corresponding to the top of the left containing cavity, of the cylinder wall of the test cylinder, a water outlet 18 is arranged at the position, corresponding to the bottom of the right containing cavity, of the cylinder wall of the test cylinder, a valve 19 capable of being opened or closed is arranged at the position, corresponding to the top of the right containing cavity, of the cylinder wall of the test cylinder, and the valve can be used as an exhaust port, an air inlet, a water inlet;
the axial loading device comprises a pressurizing cylinder 51 which is arranged and used for abutting against the end cover and the movable plate along the axial direction of the test cylinder, and in the embodiment, the axial displacement sensor is connected between the movable plate and the end cover; the axial displacement sensor is used for measuring the length change x of the soil sample along the axial direction of the test cylinder so as to calculate the axial deformation of the soil sample;
the loading force of the axial loading device is used for simulating the jacking force exerted by a jack of the shield tunneling machine on the soil bin;
in this embodiment, the water supply system includes a first water tank 81, a first switch valve 82 and a hydraulic pressure regulating valve 83, a water outlet of the first water tank is connected with the water inlet 17 of the test cartridge, and the first switch valve and the hydraulic pressure regulating valve are disposed on a connection pipeline (i.e., the water inlet pipeline) between the first water tank and the water inlet of the test cartridge.
In this embodiment, the four pressurizing cylinders of the axial loading device are distributed on the radial periphery of the shearing transmission rod in a centrosymmetric manner, the piston rods of the pressurizing cylinders are located at one end of the movable plate, the cylinder bodies of the pressurizing cylinders are fixed with the end covers, the end wall of one end of the rodless cavity of the cylinder bodies of the pressurizing cylinders is integrally arranged with the end covers, namely, the end wall of one end of the rodless cavity of the cylinder bodies of the pressurizing cylinders is a part of the end covers, and the air inlet pipelines of the cylinder bodies of the pressurizing cylinders directly penetrate through the end covers and then.
The radial extrusion ring bag is arranged in the test chamber and is positioned at the periphery of the soil sample, water is filled in the radial extrusion ring bag, the outer wall of the radial extrusion ring bag is attached to the inner wall of the test chamber under the action of water pressure, the inner wall of the radial extrusion ring bag is used for applying radial extrusion force to the soil sample, the volume and the thickness of the radial extrusion ring bag can change along with the change of the flow of the filled fluid, and further the volume of the soil sample changes and/or the length of the soil sample along the axial direction of the test cylinder changes so as to be used for simulating different soil discharge speeds of the spiral conveying mechanism of the shield machine;
in the embodiment, the left end of the shearing transmission rod is positioned in the test bin, the right end of the shearing transmission rod sequentially penetrates through the second water permeable cushion, the movable plate and the through holes formed in the end cover from left to right and then extends out of the test cylinder and is connected with the transmission mechanism, the shearing rod 4 is arranged in the test bin and is connected with the shearing transmission rod, and the transmission mechanism is provided with a torque sensor 42; the torque sensor is used for measuring and calculating the shear strength change condition of the soil sample under different working conditions, namely different simulated jacking forces and/or different simulated soil discharge speeds, and specifically, the shear strength tau of the soil sample is calculated by adopting a formula 1;
in the embodiment, the test bin pressure sensors are arranged on the inner wall of the radial extrusion annular bag, and the test bin pressure sensors are 4 groups arranged at intervals along the axial direction of the test cylinder; the test bin pressure sensor is used for detecting the pore water pressure of the soil sample in the test bin under different jacking forces and different soil discharge speeds, and further used for calculating the effective stress sigma 'of the soil sample in the test bin by combining the loading force P of the pressurizing cylinder, in the embodiment, the effective stress sigma' of the soil sample is calculated by adopting a formula 2.
In this embodiment, each group of test chamber pressure sensors 60 includes a horizontal sensor 61 respectively disposed at the horizontal quadrant point position of the inner wall of the test chamber and a vertical sensor 62 disposed below the horizontal sensor, the central points of the two sensors in the same group are located on the same radial plane of the test cylinder, the vertical sensor is used for forming a height difference with the horizontal sensor in the test chamber, and then performing a contrast test on the pore water pressure of the soil sample at different vertical height positions in the test chamber.
In this embodiment, the first and second water permeable mats include the flexible seepage bag with holes and the gravel filled in the flexible seepage bag, before each test, the flexible seepage bag with gravel is placed at each end of the soil sample, and then the soil sample is spread and pushed flat, after the test is finished, the gravel can be removed by only lifting the flexible seepage bag, so that the complex work of spreading the bulk gravel every time can be avoided, the test progress can be accelerated, the modifier in the soil sample is prevented from entering an attenuation state before the test work begins, and the accuracy of test data is improved.
The soil pressure balance shield muck workability and improvement optimization evaluation test system of this embodiment still includes turning device 25, turning device sets up in test section of thick bamboo axial one end bottom, and turning device is used for rotating 90 and making the axial direction of test section of thick bamboo become vertically by the level along the counter-clockwise in the vertical plane with empty test section of thick bamboo, and the right-hand member opening up to in toward experimental storehouse intussuseption soil sample, turning device still is used for rotating 90 and making the axial direction of test section of thick bamboo to the level along the clockwise in the vertical plane with the test section of thick bamboo that fills soil sample, so that test.
In this embodiment, earth pressure balance shield constructs dregs workability and improvement optimization evaluation test system still includes support frame 26 and sets up the supporting legs 27 in the shrouding outside, the support frame sets up at the turning device side, and the support frame is used for supporting the test section of thick bamboo when test section of thick bamboo upset to the axial approach level and keeps away from the axial other end of turning device, and the support frame top is provided with the circular-arc sunken holding surface 260 that matches with test section of thick bamboo cylinder lateral wall, and the supporting legs is used for supporting test section of thick bamboo when test section of thick bamboo upset to the axial approach is vertical, and when test section of thick bamboo upset to the axial approach level is experimental, the supporting legs is collapsible to the position with the shrouding laminating or close.
In this embodiment, the first water tank 81 includes a main tank 810 and a water level monitoring pipe 811 having a bottom communicated with the main tank and used for observing the water amount of the water tank, the water outlet of the first water tank is disposed at the bottom of the main tank, and the main tank and the top of the water level monitoring pipe are connected in parallel to a pressure air source through a pipeline.
In this embodiment, the pressure air source includes a motor 31, an air compressor 32, an air storage tank 33, a first air path 34, a first air pressure regulating valve 35, a second air path 36, a second air pressure regulating valve 37, a third air path 38 and a third air pressure regulating valve 39, the motor is used for connecting and driving the air compressor, an inlet of the air storage tank is connected with an outlet of the air compressor, the air storage tank is used for storing pressure air, the first air path, the second air path and the third air path are all connected to an outlet of the air storage tank, the other end of the first air path is connected with an inlet of the first water tank, the other end of the second air path is connected with a pressurizing cylinder of the axial loading device, the other end of the third air path is connected with the radial extrusion annular bag to provide pressure required for fluid filling to the radial extrusion annular bag, the first air pressure regulating valve is disposed on the first, the first air pressure regulating valve is used for regulating the water supply pressure of the first water tank, the second air pressure regulating valve is used for regulating the air inlet pressure of a pressurizing air cylinder of the axial loading device, and the third air pressure regulating valve is used for regulating the fluid filling pressure of the radial extrusion annular bag.
In this embodiment, the fluid pressure medium in the radial extrusion annular bag is water, the water supply system further comprises a second water tank 84, a second switch valve 85 and an electromagnetic proportional flow valve 86, the water outlet of the second water tank is connected with the radial extrusion annular bag, the second switch valve and the electromagnetic proportional flow valve are arranged on a connecting pipeline between the second water tank and the inlet of the radial extrusion annular bag, the electromagnetic proportional flow valve is used for controlling the flow rate of the water filled in the radial extrusion annular bag to adjust the volume of the radial extrusion annular bag, thereby changing the radial extrusion force and simulating the constantly changing soil discharging speed, when the water quantity filled in the radial extrusion annular bag reaches a certain set value, and stopping filling water into the radial extrusion annular bag through the second switch valve to keep the volume of the radial extrusion annular bag at a certain fixed value, and simulating a fixed soil discharging speed.
In this embodiment, the radially compressible annular capsule is also provided with an outlet (not shown) to the outside of the test cartridge, which is also provided with an electromagnetic proportional flow valve (not shown) for controlling the discharge flow of the radially compressible annular capsule and an electromagnetic on-off valve (not shown) for closing or opening the outlet.
The soil pressure balance shield muck workability and improvement optimization evaluation test system of this embodiment still changes including good agent addition system, modifier addition system includes modifier generating device 71 and modifier conveying line 72, modifier conveying line entry end is connected with modifier generating device, and modifier conveying line is provided with a plurality of exit ends 73 along the axial direction interval distribution of test section of thick bamboo, and each exit end passes in stretching into the test storehouse behind the hole that sets up on test section of thick bamboo lateral wall and the radial extrusion ring bag, and modifier conveying line is used for pouring into the modifier into the test storehouse toward filling muck, and the shearing pole still can be used to carry out the stirring to muck and modifier in the test storehouse and mix.
Be provided with modifier pipeline in the experimental storehouse, because the decay is faster after modifier and dregs mix, pour into the experimental storehouse again with modifier after soil sample is filled in, can strive for more time for the workability test of follow-up soil sample for the experimental test result is more accurate. In addition, the plurality of shearing rods connected with the tail end of the shearing transmission rod can be used for testing the soil sample strength and can also be used as a stirring tool of the modifying agent, so that the device is very convenient and fast.
In this embodiment, the hydraulic pressure regulating valve, the first air pressure regulating valve, the second air pressure regulating valve and the third air pressure regulating valve all adopt electromagnetic proportional pressure reducing valves, the first switch valve and the second switch valve all adopt electromagnetic switch valves, the soil pressure balance shield muck workability and improvement optimization evaluation test system of this embodiment further comprises a control terminal 9, the axial displacement sensor, each test bin pressure sensor and each torque sensor are all connected with the control terminal, the axial displacement sensor and each test bin pressure sensor and each torque sensor respectively transmit measured real-time displacement data, pressure data and torque data to the control terminal, and the control terminal is convenient to calculate the workability-related parameters of the soil sample.
The water pressure regulating valve, the air pressure regulating valve I, the air pressure regulating valve II, the air pressure regulating valve III and the switch valve I are also electrically controlled by the control terminal; the control terminal adjusts the water pressure provided by the soil sample in the pair of test cylinders by adjusting and controlling the outlet water pressure of the water pressure adjusting valve, the control terminal adjusts the pressure provided by the pressure air source to the water tank by adjusting the outlet air pressure of the air pressure adjusting valve I, the control terminal adjusts the loading force of the pressurizing air cylinder by adjusting the outlet air pressure of the air pressure adjusting valve II, and the control terminal adjusts the pressure provided by the pressure air source to the water tank II by adjusting the outlet air pressure of the air pressure adjusting valve III.
The experimental method for the soil pressure balance shield muck workability and the improved optimization evaluation test system based on the embodiment comprises the following steps of testing the workability of a soil sample in any one of the following three simulation working conditions:
the method comprises the following steps of simulating a first working condition, controlling the volume of a fluid pressure medium in a radial extrusion ring bag to be unchanged, changing the air inlet pressure of a pressurizing air cylinder of an axial loading device, simulating an axial pushing mechanism to apply different pushing forces to a soil bin of the shield tunneling machine, and testing the workability of a soil sample under the simulated working condition;
simulating a working condition II, keeping the air inlet pressure of a pressurizing air cylinder of the axial loading device unchanged, changing the volume of a fluid pressure medium in the radial extrusion ring bag, simulating the change of the soil discharging speed of a spiral conveying mechanism of the shield tunneling machine, and testing the workability of the soil sample under the simulated working condition;
simulating a working condition III, enabling the air inlet pressure of a pressurizing air cylinder of the axial loading device and the volume of the fluid pressure medium in the radial extrusion ring bag to synchronously change, simulating the synchronous change of the jacking force of the shield tunneling machine and the soil discharging speed of the spiral conveying mechanism, and testing the workability of the soil sample under the simulated working condition;
the workability test of the soil sample comprises any one or more tests of permeability of the soil sample, shear strength tau of the soil sample and deformation characteristics of the soil sample.
In the three simulation working conditions, water flows with different pressures are applied to the soil sample in the test bin, namely different water pressures are applied, the permeability characteristic of the soil sample is synchronously tested, and the soil sample is applied to the calculation of the effective stress sigma' and the effective strength parameter.
The permeability test of the soil sample comprises calculating the permeability coefficient K of the soil sample by adopting the formula 2T。
The effective stress σ' of the soil sample is calculated using equation 3.
The deformation characteristic test of the soil sample comprises the steps of calculating the porosity E of the soil sample by adopting a formula 4 and calculating the compression modulus E of the soil sample by adopting a formula 50。
The strength test of the soil sample comprises the step of measuring and calculating the friction angle of the soil sample under any two simulation working conditions
And cohesion c of the soil sample, referring to the schematic diagram of FIG. 5, and calculating the frictional angle of the soil sample using equation 6
The cohesion c of the soil sample was calculated by equation 7:
τ1、τ2the soil sample strength sigma 'is measured and calculated by formula 1 at two data acquisition moments or under any two simulation working conditions in the test process'1、σ′2The effective stress of the soil sample is obtained by the formula 2 measurement and calculation at two data acquisition moments or any two simulation working conditions in the test process.
It should be noted that, for convenience of description, the horizontal axial two ends of the test cartridge are defined as the left and right directions, and the actual left and right directions are interchangeable, so the definition of the left and right directions of the test cartridge in the present invention does not limit the protection scope of the present invention.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (4)
1. The earth pressure balance shield muck workability and improvement optimization evaluation test method is characterized in that an earth pressure balance shield muck workability and improvement optimization evaluation test system is adopted to simulate the working condition of a shield machine, the workability of an earth sample is tested in the simulated working condition, and the earth pressure balance shield muck workability and improvement optimization evaluation test system comprises a test cylinder (1), a shearing rod (4), a shearing transmission rod (41), an axial loading device (5), an axial displacement sensor (32), a radial extrusion ring capsule (6) and a test bin pressure sensor (60);
the axial direction of the test cylinder is arranged along the horizontal direction, a test bin (15) is arranged in the test cylinder, one end of the shearing transmission rod is positioned in the test bin, the shearing rod is connected to one end of the shearing transmission rod, which is positioned in the test bin, the other end of the shearing transmission rod extends out of the test cylinder and is connected with a transmission mechanism, and a torque sensor (42) is arranged on the transmission mechanism and is used for testing the shearing strength tau of different soil samples under different simulation working conditions;
the radial extrusion ring bag is arranged in the test bin and is positioned at the periphery of the soil sample, a fluid pressure medium is filled in the radial extrusion ring bag, the outer wall of the radial extrusion ring bag is attached to the inner wall of the test bin under the pressure action of the fluid pressure medium, the inner wall of the radial extrusion ring bag is used for applying radial extrusion force to the soil sample, and the volume and the thickness of the radial extrusion ring bag can be changed along with the change of the flow of the charged fluid, so that the volume of the soil sample is changed to simulate different soil discharge speeds of a spiral conveying mechanism of the shield tunneling machine;
the axial loading device comprises a pressurizing cylinder which is propped between an end cover and a movable plate along the axial direction of the test cylinder, and an axial displacement sensor is used for measuring the length change x of the soil sample along the axial direction of the test cylinder so as to test the deformation characteristic of the soil sample;
the test bin pressure sensors are arranged on the inner wall of the radial extrusion annular bag and are arranged at intervals along the axial direction of the test cylinder; the test bin pressure sensor is used for monitoring the pore water pressure of the soil sample in the test bin under any one or more working condition combinations of different water pressures, different top thrusts and different soil discharging speeds; and further used for calculating the effective stress sigma' of the soil sample in the test bin by combining the loading force P of the pressurizing cylinder;
the soil pressure balance shield muck workability and improvement optimization evaluation test method comprises the following steps of testing the workability of a soil sample in any one of the following three simulation working conditions:
the method comprises the following steps of simulating a first working condition, controlling the volume of a fluid pressure medium in a radial extrusion ring bag to be unchanged, changing the air inlet pressure of a pressurizing air cylinder of an axial loading device, simulating an axial pushing mechanism to apply different pushing forces to a soil bin of the shield tunneling machine, and testing the workability of a soil sample under the simulated working condition;
simulating a working condition II, keeping the air inlet pressure of a pressurizing air cylinder of the axial loading device unchanged, changing the volume of a fluid pressure medium in the radial extrusion ring bag, simulating the change of the soil discharging speed of a spiral conveying mechanism of the shield tunneling machine, and testing the workability of the soil sample under the simulated working condition;
simulating a working condition III, enabling the air inlet pressure of a pressurizing air cylinder of the axial loading device and the volume of the fluid pressure medium in the radial extrusion ring bag to synchronously change, simulating the synchronous change of the jacking force of the shield tunneling machine and the soil discharging speed of the spiral conveying mechanism, and testing the workability of the soil sample under the simulated working condition;
the workability test of the soil sample comprises any one or more of the permeability of the soil sample, the shear strength tau of the soil sample and the deformation characteristic of the soil sample;
the soil pressure balance shield muck workability and improvement optimization evaluation test method further comprises the steps of applying water flows with different pressures to the soil sample in the test bin in the three simulation working conditions, namely applying different water pressures, synchronously testing the permeability characteristic of the soil sample and applying the permeability characteristic to the calculation of effective stress sigma' and effective strength parameters;
the shear strength tau of the soil sample is calculated by adopting formula 1:
the shearing device comprises a shearing rod, a torque sensor, a transmission mechanism, a shearing rod, a driving mechanism and a driving mechanism, wherein M is the torque which is measured by the torque sensor and applied to the shearing transmission rod by the transmission mechanism, a is the transverse size of the shearing rod, theta is an included angle between the shearing rod and the shearing transmission rod, H is the sine value of the length of the shearing rod multiplied by the angle theta, and L is the cosine value of the length of the shearing rod;
the permeability test of the soil sample comprises the step of calculating the permeability coefficient K of the soil sample by adopting the formula 2T：
Where ρ iswIs the density of water, t is the permeation time, Q is the amount of water permeated within the time t, and g is the acceleration of gravity;
the effective stress sigma' of the soil sample is calculated by adopting formula 3:
wherein m is the number of the pressurizing cylinders, d is the inner diameter of the test chamber, and h0Is the axial initial length size of the soil sample before loading, x is the length variation of the soil sample along the axial direction of the test cylinder, QhThe water filling volume of the annular bag is radially extruded, S is the distance between two adjacent test bin pressure sensors along the axial direction of the test cylinder, n is the number of the test bin pressure sensors, P'nPore water pressure measured by the pressure sensor of the nth test bin;
the deformation characteristic test of the soil sample comprises the steps of calculating the porosity E of the soil sample by adopting a formula 4 and calculating the compression modulus E of the soil sample by adopting a formula 50：
Wherein w is the moisture content of the muck sample before improvement, m is the quality of the muck sample before improvement, rhosIs residue soil before improvementThe density of the particles of the sample;
the soil pressure balance shield muck workability and improvement optimization evaluation test system further comprises a modifier generating device (71) and a modifier conveying pipeline (72), wherein the inlet end of the modifier conveying pipeline is connected with the modifier generating device, the outlet end (73) penetrates through the side wall of the test cylinder and then extends into the test bin or sequentially penetrates through the end cover and the movable plate and then extends into the test bin, the modifier conveying pipeline is used for injecting a modifier into the test bin filled with muck, and the shearing rod is also used for stirring and mixing the muck and the modifier in the test bin;
the soil pressure balance shield muck workability and improvement optimization evaluation test method further comprises the steps of adding a modifier to the same soil sample through a modifier adding system after the workability test of the same soil sample in any one of the simulation working conditions is finished, carrying out improvement optimization, and carrying out any one of the simulation working condition tests on the improved soil sample to obtain the workability change test data before and after the improvement of the same soil sample for evaluation comparison of the improvement method.
2. The soil pressure balance shield muck workability and improvement optimization evaluation test method according to claim 1, the system is characterized by further comprising a fixed plate (21), a movable plate (22), a first water permeable cushion (23) and a second water permeable cushion (24) which are arranged in the test cylinder, the left end of the shaft of the test cylinder is sealed by a seal plate (11), the right end of the shaft of the test cylinder is provided with an opening, the right end opening is sealed by a detachable end cover (12), the fixed plate and the movable plate are both provided with water permeable holes (13), the plate surfaces of the fixed plate and the movable plate are both arranged along the vertical direction, a second interval for forming the test bin (15) is kept between the fixed plate and the movable plate along the axial direction of the test cylinder, the first water permeable cushion is used for being arranged between the fixed plate and the soil sample in the test bin in a spaced mode, and the second water permeable cushion is used for being arranged between the movable plate and the soil sample in the test bin in a spaced mode.
3. The soil pressure balance shield muck workability and improvement optimization evaluation test method according to claim 1, wherein the pressurizing cylinders are m in a centrosymmetric structure distributed on the radial periphery of the shearing transmission rod, m is an integer greater than or equal to 2, a piston rod of each pressurizing cylinder is located at one end of the movable plate, a cylinder body of each pressurizing cylinder is fixed with the end cover, the end wall of one end of a rodless cavity of the cylinder body of each pressurizing cylinder is integrally arranged with the end cover, and an air inlet pipeline of each cylinder body of each pressurizing cylinder directly penetrates through the end cover and then is introduced into the rodless cavity.
4. The soil pressure balance shield muck workability and improvement optimization evaluation test method according to claim 1, wherein the test bin pressure sensors are arranged at intervals along the axial direction of the test cylinder, and each test bin pressure sensor (60) is arranged at a position of a transverse quadrant point of the inner wall of the test bin, which is in the same horizontal plane as the shear transmission rod.
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| CN113240999B (en) * | 2021-06-22 | 2023-03-14 | 腾达建设集团股份有限公司 | Test device and test method for improving muck synchronously during shield tunneling and soil cutting |
| CN114279818B (en) * | 2021-12-31 | 2023-06-16 | 西南交通大学 | Bidirectional flexible loading and unloading ring shear device and test method thereof |
| CN116297105B (en) * | 2023-03-30 | 2023-11-28 | 浙江大学 | Device and method for simulating three-dimensional dynamic slurry permeation test under supergravity |
| CN118091084A (en) * | 2024-02-29 | 2024-05-28 | 济南城建集团有限公司 | Foam improved soil generation and mesoscopic characterization device for simulating high-pressure environment |
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