CN212568764U - Induced grouting experimental model for saturated fine sand layer - Google Patents
Induced grouting experimental model for saturated fine sand layer Download PDFInfo
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- CN212568764U CN212568764U CN202020288829.7U CN202020288829U CN212568764U CN 212568764 U CN212568764 U CN 212568764U CN 202020288829 U CN202020288829 U CN 202020288829U CN 212568764 U CN212568764 U CN 212568764U
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Abstract
An induced grouting experimental model of a saturated fine sand layer belongs to the field of foundation and geotechnical engineering research. The experimental model comprises: the system comprises a model system, a grouting control system, a negative pressure induction system and an intelligent monitoring system; the principle of induced grouting is provided; the invention monitors different porosities, water pressures, flow rates, time, consistencies and slurry diffusion rules under different flowing water flow states by changing conditions such as pressure, grouting modes, grouting time, sand layer structures and slurry components, and researches related information such as slurry diffusion, flow rate change, osmotic pressure distribution and energy loss monitoring in the grouting process. The invention can directionally grouting and directionally reinforcing the foundation in a saturated sandy soil foundation in a negative pressure induction mode, and the range and the effect of reinforcing the foundation can be realized according to the requirements of engineering and the induction grouting principle.
Description
The technical field is as follows:
the utility model relates to a foundation grouting reinforcement processing technology is applicable to underground works such as subway and saturates sand soil foundation reinforcement and stagnant water, belongs to ground and geotechnical engineering research field.
Background art:
the silt fine layer is a sandy soil stratum with the mass of particles with the particle size of more than 0.075mm exceeding 50% of the total mass and the mass of particles with the particle size of more than 0.25mm being less than 50% of the total mass, belongs to loose sediments formed in the quaternary period and is widely distributed.
The fine sand is in a natural state, has poor cementation, loose structure and lower bearing capacity, can be compacted under the action of self weight, the density of a fine sand layer is increased along with the increase of the buried depth, and the fine sand belongs to a medium water-permeable stratum with the permeability coefficient of 6 multiplied by 104～6×103cm/s, the coefficient of non-uniformity of the silt is generally not more than 5.
The saturated fine silt is positioned below a diving ground and is saturated with water, the penetration damage mode is mainly soil running, the subsequent sand running phenomenon occurs, and the damage slippage is often instantaneous and is difficult to control.
With the development and utilization of underground space, a large amount of underground engineering such as subways and the like pass through a saturated fine sand layer, collapse, sand gushing and other disasters are easy to generate in the construction process, and the pre-reinforcement treatment is very necessary.
Grouting is a common means for reinforcing weak strata, scholars at home and abroad carry out a large number of engineering tests and theoretical researches, grouting slurry is injected into surrounding rocks through pore-forming, the slurry is diffused to cracks of the surrounding rocks under certain grouting pressure, a reinforcing strip (grouting curtain) is formed on a rock body, the integrity of the rock body is improved, and the strength of the surrounding rocks is enhanced.
The permeability and the injectability of the saturated fine powder layer are extremely poor, the conventional grouting technology cannot enable slurry to permeate into a stratum to form an effective reinforcing body, a large number of grouting theories are proposed for a long time, a large number of field tests are carried out, the grouting effect is extremely poor, and the research on the saturated fine powder layer grouting experiment has important theoretical significance and engineering application value.
SUMMERY OF THE UTILITY MODEL
The utility model discloses a thin sand layer of saturated powder induction slip casting experimental model and experimental approach, according to bulk mechanics, continuous medium mechanics and hydrodynamics theory, according to function principle, potential energy principle and stack principle etc. propose the induction slip casting principle (induced splitting condition and can annotate the condition), adopt on-the-spot intelligent detection method and mathematical calculation method to design the thin sand layer of saturated powder induction slip casting experimental model and experimental approach.
The utility model discloses induced slip casting experimental model of fine sand layer of saturated powder includes: the system comprises a model system (1), a grouting control system (2), a negative pressure induction control system (3) and an intelligent monitoring system (4); the composition of each system is as follows:
the model system (1) comprises a model groove (1.1) and a test soil body (1.2) positioned in the model groove;
the mould groove (1.1) comprises: a model groove plate (1.1.1) made of organic glass, a model groove reinforcing bar steel (1.1.2) and a rubber sealing gasket (1.1.3);
the test soil body (1.2) comprises from bottom to top: a fine sand layer (1.2.3), a clay water stopping layer (1.2.2) and a geomembrane (1.2.1);
the grouting system (2) comprises a grouting pump (2.1), a grouting pressure controller (2.2), a pressurization box (2.3) and a grouting control valve (2.6) which are sequentially connected, metal grouting pipes (2.4) are adopted for connection, and an embedded grouting pipe (2.5) finally connected with the metal grouting pipes (2.4) extends into a test soil body (1.2);
the negative pressure induction control system (3) comprises a negative pressure pump (3.1), a negative pressure induction drainage negative pressure controller (3.2) and a water pumping control valve (3.5) which are connected in sequence, the negative pressure induction drainage negative pressure controller, the water pumping control valve and the water pumping control valve are connected by a metal drainage pipe (3.3), and finally, a pre-buried negative pressure pipe (3.4) is connected and extends into a test soil body (1.2); a plurality of water pumping control valves (3.5) can be connected in parallel, and each parallel pipeline is connected with a pre-embedded negative pressure pipe (3.4) respectively at last and extends into a test soil body (1.2) and the water pumping control valves (3.5);
the intelligent monitoring system (4) comprises various sensors (a pore water stress sensor, a temperature sensor, a soil pressure sensor, a flow velocity sensor and the like) (4.1) positioned in a test soil body (1.2), a grouting pressure gauge (4.2) arranged on a pipeline of the grouting system (2), a negative pressure gauge (4.3) arranged on a pipeline of the negative pressure induction control system (3), an intelligent detection collector (4.4) and a system monitoring platform (4.5); each sensor (4.1), the grouting pressure gauge (4.2) and the negative pressure gauge (4.3) are connected with a system monitoring platform (4.5) through an intelligent detection collector (4.4).
The mould groove is formed by splicing transparent organic glass steel plates (1.1.1) and is fixedly connected by section steel reinforcing strips (1.1.2) to prevent the mould groove from deforming, and a rubber sealing gasket (1.1.3) seals the upper opening of the mould groove; filling a soil body powder fine sand layer (machine-made quartz sand or river sand) (1.2.3) for the test in a layering manner in the model groove, and performing layering water stopping by adopting a clay water stopping layer (1.2.2) and a geomembrane (1.2.1) in a layering manner;
the internal pre-buried slip casting pipe (2.5) and pre-buried negative pressure pipe (3.4) respectively of experimental soil, pre-buried slip casting pipe (2.5) and pre-buried negative pressure pipe (3.4), adopt the clear glass pipe, pre-buried slip casting pipe (2.5) pipe end sets up the circular injected hole of a certain amount, outwards sprays the slip casting thick liquid under high-pressure state, set up the circular filtration pore of a certain amount at pre-buried negative pressure pipe (3.4) pipe end, the outsourcing filter screen filters the grains of sand and carries out the negative pressure drainage.
The model system comprises a model groove and a soil body, and the whole grouting experiment is completed in the model system; in order to observe the flowing condition, the grouting process and the grouting effect of slurry (5.1) and water (5.2) in the experimental tank, the size of the tank body of the model tank (1.1) is determined according to the size of sand particles and the size of slurry (5.1) particles and according to a similar law, the proportion and the grouting parameters of the model are determined by adopting a transparent organic glass plate (1.1.1), the length of the tank body is L, the width of the tank body is B, the height of the tank body is H, and the specific size of the tank body accords with the similar proportion.
The grouting control system (2) is characterized in that enough grouting slurry (5.1) with specified components and proportion is provided by a grouting pump (2.1), a pressurizing box (2.3) is injected under the control of a grouting pressure controller (2.2) to form stable pressure and slurry, a grouting control valve (2.6) is used for controlling grouting time and grouting pressure, a soil body is grouted by a pre-embedded grouting pipe (2.5), the slurry enters the soil body through the grouting pipe to form a positive pressure ring in a certain range, and the slurry is diffused and transported in the soil body along a specified direction under the induction of a certain pressure (negative pressure induction system) to form a retention body and a reinforced soil body (5.3).
The negative pressure induction control system (3) provides stable negative pressure by a negative pressure pump (3.1), a water pumping control valve (3.5) and a drainage negative pressure controller (3.2), a negative pressure gauge (4.3) and the like detect and control the size and time of the negative pressure, liquid (water body (5.2)) is formed in an embedded negative pressure pipe (3.4) to induce the negative pressure, water in a soil body is sucked out under the negative pressure state to form a negative pressure ring in a certain range in the soil body, and slurry under the induced positive pressure moves to the negative pressure direction to form a retention body and a reinforced soil body (5.3).
The grouting principle during grouting of the utility model comprises an induced splitting condition and a grouting condition, when the difference between the slurry diffusion positive pressure and the induced negative pressure at any point in the soil body is greater than the flow resistance of the slurry in the soil body, the slurry is diffused and moved along the specified inducing direction, and a detention body and a reinforced soil body (5.3) are formed in the soil body under the control of pressure;
the grouting principle comprises an induced cleavage condition and a grouting condition:
the induced splitting condition of the grouting principle is to set tau0Is the ultimate shear stress of the slurry, v is the slurry speed in the channel direction,
the average speed of the slurry is determined, mu is a viscosity coefficient, b is a splitting opening coefficient, and the micro-pressure stress at any point r away from the grouting hole when the slurry flows is determined as follows:
let gamma be severe, K0The stress borne by any microcell is the self-weight stress p of the upper earth covering as the lateral pressure coefficientzPressure p of the lateral pressurekAnd grouting pressure p1Or negative pressure p of pumping water2The stress borne by any micro unit of the sandy soil layer at the buried depth Z in the vertical direction is the self-weight stress p of the upper earthing soilzI.e. by
pz＝γZ (2)
The microcells are subjected to stress p in the horizontal directionhFor filling/pumping water pressure piAnd side pressure pkResultant force of (i.e.
ph＝pi+pk＝pi+K0γZ (3)
According to the flow equation of the slurry, the distance from the microcell bodies to the grouting holes is set as r1The distance between the negative pressure water pumping holes is r2The maximum influence distance of the grouting hole is R1The maximum influence distance of the negative pressure water pumping hole is R2The horizontal stress on any micro-unit can be obtained as
Namely, for any microcell, the grouting additional stress is set as follows:
the negative pressure additional stress is:
the resultant of the injection/pumping pressures in the horizontal direction is:
ph(r)＝p1(r1)+p2(r2) (5)
according to the cleavage direction, for any one of the microcells, if pz﹥ph(r) then cleavage, p, occurs in the vertical directionz﹤ph(r) splitting in the horizontal direction if pz＝ph(r) the cleavage direction is random.
The grouting principle can be applied under the condition that according to the rheological theory, the rheological property of any fluid including grouting slurry can be described by a rheological model, and the plastic viscosity is set to be muρWhen the friction shear stress is tau and the shear rate (flow rate gradient) is xi when the slurry flows, the rheological equation of the plastic fluid is as follows:
τ＝τ0+μρ.ξ (6)
for any one of the microcells, if ph(r)>Tau, the slurry will produce seepage motion along the horizontal direction and has injection property.
In summary, it is only necessary that p is satisfied in any of the microcells between the inlet (5.4) and the outlet (5.5)z﹥ph(r) induced directional cleavage can be generated along the direction from the grouting hole (5.4) to the water absorption hole (5.5); if p ish(r)>Tau, the slurry generates seepage motion along the horizontal direction, and has injectability, thus realizing directional grouting.
In the whole experiment drainage induction grouting process, the grouting monitoring system monitors relevant influence conditions of soil body pressure, grouting pressure, pore water pressure, flow rate of water and slurry, temperature and the like of the model through the monitoring system (4), collects experiment data and analyzes experiment results. In the system, a plurality of sensors (4.1) are adopted to collect data (the types of the sensors comprise sensors of soil body pressure, grouting pressure, pore water pressure, flow rate of water and slurry, temperature and the like) in the experimental process, and an intelligent detection collector (4.4) is utilized to transmit the data to a system monitoring platform (4.5) and record the data. The grouting pressure gauge (4.2) is used for observing and recording grouting pressure in the grouting process, so that the proper grouting pressure can be adjusted in time; the negative pressure gauge (4.3) monitors the negative pressure of drainage in the drainage system in the grouting process, so that the negative pressure value of drainage can be observed and controlled at any time.
The grouting method is characterized in that conditions such as pressure, grouting mode, grouting time, sand layer structure and slurry components are changed to monitor different porosities, water pressures, flow rates, time and consistencies and slurry diffusion rules under different flowing water flow conditions, and relevant information such as slurry diffusion, flow rate change, osmotic pressure distribution and energy loss monitoring in the grouting process is researched.
The experimental groups consist in the following grouping by different environmental conditions:
a first group: the water injection test is to measure the pore water pressure and flow speed, the soil pressure, the grouting time, the grouting pressure and the negative pressure of pumping in the soil body, observe the flow direction and the track, thereby calculating parameters such as the flow speed and the flow field potential, and drawing a slurry and a water flow field and the like;
second group: the cement paste is divided into three groups according to different mixing ratios for testing, the three groups of tests adopt different mixing ratios, the pore water pressure and the flow speed in the soil body, the soil pressure, the grouting time, the grouting pressure and the negative pressure of pumping water are measured, the flow direction and the track are observed, so that parameters such as the flow speed and the flow field potential are calculated, and the grout, the water flow field and the like are drawn;
third group: testing in five groups according to the grouting pressure, measuring the pore water pressure and flow speed, the soil pressure, the grouting time, the grouting pressure and the negative pressure of pumping in the soil body, observing the flow direction and the track, thereby calculating parameters such as the flow speed and the flow field potential, drawing a slurry and a water flow field and the like;
and a fourth group: dividing into three groups according to different grouting time, measuring pore water pressure and flow speed, soil pressure, grouting time, grouting pressure and negative pressure of pumping water in a soil body, observing flow direction and track, calculating parameters such as flow speed and flow field potential, drawing slurry and water flow field, and the like;
and a fifth group: for sands with different components and particle sizes, dividing a model into two groups according to the combined structure of different sand layers (machine-made sand or river sand), namely machine-made sand and river sand respectively, adopting a proper water-cement ratio and different grouting pressures, respectively performing grouting tests, measuring the pore water pressure and flow speed in a soil body, soil pressure, grouting time, grouting pressure and water pumping negative pressure, observing the flow direction and track, calculating parameters such as flow speed and flow field potential, drawing a slurry and water flow field and the like.
The implementation method comprises the following steps:
model system (1): the whole grouting experiment is completed in the model system (1). In order to observe the water flow condition, the grouting condition and the grouting effect in the experimental groove, the groove body of the model groove (1.1) is made of a transparent organic glass model groove plate (1.1.1), the length of the groove body is L, the width of the groove body is B, the height of the groove body is H, and the specific size of the groove body can be reduced according to a certain proportion according to engineering; in order to effectively prevent the model groove from deforming or damaging under the pressure action of the soil body (1.2), the middle part of the model groove plate (1.1.1) is properly reinforced by a section steel reinforcing strip (1.1.2); the edge of the cover plate at the top of the model groove (1.1) is sealed by a rubber sealing gasket (1.1.3), the model groove is kept sealed, and the pressure difference inside the soil body (1.2) is kept stable in the grouting process. The soil body (1.2) in the experiment is paved into a plurality of layers according to the experimental condition, and the paving sequence of each layer is sequentially a fine sand layer (1.2.3), a clay water stopping layer (1.2.2) and a geomembrane (1.2.1) from bottom to top. Wherein the fine sand layer (1.2.3) is replaced by machine-made quartz sand and river sand; the clay water stopping layer (1.2.2) and the geomembrane (1.2.1) are used for manufacturing the water stopping layer, so that a better sealing effect is achieved, and the pressure difference inside the soil body (1.2) in the grouting process is kept stable.
Grouting control system (2): the grouting control system (2) injects a continuous homogeneous slurry (5.1) for the model system (1) in the experiment. In the grouting process, the grouting pump (2.1) is responsible for providing grout for the whole grouting control system (2); the grouting pressure controller (2.2) is used for controlling the grouting pressure of the system and adjusting the grouting pressure at any time; the pressure tank (2.3) is used for providing stable grouting pressure, so that the grout (5.1) is stably and uniformly injected into the soil body. The pre-buried grouting pipe (2.5) is a transparent glass pipe, a certain number of circular grouting holes (5.4) are formed in the tail end of the pipe, and grout (5.1) is sprayed outwards in a high-pressure state. The pre-buried quantity and the pre-buried position of the pre-buried grouting pipes (2.5) can be determined according to specific experiments or construction conditions. The whole grouting control system (2) is connected through a metal grouting pipe (2.4).
Negative pressure induction control system (3): the whole negative pressure induction control system (3) generates negative pressure by sucking water in the model system (1), induces seepage of slurry (5.1) according to the negative pressure direction, forms a retention body and a reinforced soil body (5.3) in the soil body, and achieves the purpose of reinforcing the foundation. The negative pressure pump (3.1) is a source of negative pressure in the whole model and discharges water in the drainage control system (3); the negative pressure controller (3.2) is used for controlling the negative pressure and the drainage speed in the drainage process so as to achieve a better grouting induction effect; the tail end of the embedded negative pressure pipe (3.4) is provided with a certain number of circular water suction holes (5.5), and a filter screen (5.7) is coated outside the embedded negative pressure pipe to filter sand grains and perform negative pressure drainage. The pre-buried quantity and the pre-buried position of the pre-buried negative pressure pipe (3.4) can be determined according to specific experiments or construction conditions. The whole drainage control system (3) is connected through a metal negative pressure pipe (3.3).
Monitoring system (4): in the whole experiment drainage induction grouting process, relevant influence conditions such as soil body pressure, grouting pressure, pore water pressure, flow rate of water and slurry, temperature and the like of the model are monitored through the monitoring system (4), experiment data are collected, and experiment results are analyzed. In the system, a plurality of sensors (4.1) are adopted to collect data in an experiment, the data are connected with an intelligent monitoring collector (4.4) through a lead (5.6), and the data are transmitted to a system monitoring platform (4.5) and recorded. The grouting pressure gauge (4.2) arranged in the grouting control system (2) is used for observing and recording grouting pressure in the grouting process, so that proper grouting pressure can be adjusted conveniently and timely. And a negative pressure gauge (4.3) arranged in the negative pressure system (3) monitors the negative pressure of drainage in the drainage control system in the grouting process, so that the negative pressure value of drainage can be observed and controlled conveniently at any time.
Grouping experiments:
the utility model discloses a change conditions such as pressure, slip casting mode, slip casting time, sand bed structure and thick liquid composition, monitor different porosity, water pressure, velocity of flow, time, consistency and thick liquid diffusion law under the different flowing water flow state conditions, relevant information such as research slip casting in-process monitoring thick liquid diffusion, velocity of flow change, osmotic pressure distribution and energy loss.
A first group: a water injection test, in which pore water pressure and flow field, soil pressure, grouting time, grouting pressure and negative pressure of pumping in a soil body are measured, and the flow direction and track are observed, so that parameters such as flow speed, flow field potential and the like are calculated;
second group: the cement paste is divided into three groups according to different mixing ratios for testing, the three groups of experiments adopt different mixing ratios, the pore water pressure and the flow field in the soil body, the soil pressure, the grouting time, the grouting pressure and the negative pressure of pumping are respectively measured, the flow direction and the track are observed, and therefore parameters such as the flow speed, the flow field potential and the like are calculated;
third group: performing tests in five groups according to the grouting pressure, respectively measuring the pore water pressure and the flow field in the soil body, the soil pressure, the grouting time, the grouting pressure and the negative pressure of pumping, and observing the flow direction and the track, thereby calculating parameters such as the flow speed, the flow field potential and the like;
and a fourth group: dividing the soil into three groups according to different grouting time, respectively measuring the pore water pressure and the flow field, the soil pressure, the grouting time, the grouting pressure and the negative pressure of pumping water in the soil body, and observing the flow direction and the track so as to calculate parameters such as the flow speed, the flow field potential and the like;
and a fifth group: according to different materials of the saturated fine sand layer (1.2.3), quartz sand and river sand are respectively adopted to carry out two groups of experiments. The method comprises the steps of adopting a proper water-cement ratio and adopting different grouting pressures to respectively perform grouting tests, measuring the pore water pressure and the flow field, the soil pressure, the grouting time, the grouting pressure and the negative pressure of water pumping in the soil body, and observing the flow direction and the track, thereby calculating parameters such as the flow speed, the flow field potential and the like.
The utility model provides an experimental model and experimental method have following beneficial effect: the method has the advantages that the directional grouting and the directional reinforcement of the foundation can be realized by the negative pressure induction mode for the saturated sandy soil foundation, and the range and the effect of the reinforcement of the foundation can be realized according to the requirement of engineering and the induction grouting principle; the utility model provides an experimental model suitable for induced slip casting experimental method has proposed the principle of induced slip casting, can accurately obtain relevant slip casting parameter according to slip casting parameter and slip casting law under the model research engineering geology before the construction to reach the cost-effective, green, effective slip casting and the purpose of pertinence reinforcement ground.
Drawings
FIG. 1 is a general schematic of a model system.
FIG. 2 is a schematic view of a mold slot;
figure 3 is a view of the stratification and internal construction of the soil.
Fig. 4 is a schematic diagram of a grouting control system.
FIG. 5 is a schematic view of a negative pressure control system.
Fig. 6 is a smart monitoring system intent.
Fig. 7 is a schematic view of the shape of the grouting reinforcement area.
Fig. 8 is a schematic diagram of an embedded grouting pipe and an embedded negative pressure pipe.
The attached drawings are marked as follows:
1. a model system; 1.1 forming a groove; 1.2, soil body; 1.1.1, a model groove plate; 1.1.2, a section steel reinforcing bar; 1.1.3, a rubber sealing gasket; 1.2.1, geomembrane; 1.2.2, clay water stopping layer; 1.2.3 fine sand layer.
2. A grouting control system; 2.1, grouting pump; 2.2, a grouting pressure controller; 2.3, a pressure tank; 2.4, a metal grouting pipe; 2.5, embedding a grouting pipe; 2.6, a grouting control valve.
3. A negative pressure control system; 3.1, a negative pressure pump; 3.2, a negative pressure controller; 3.3, a metal negative pressure pipe; 3.4, embedding a negative pressure pipe; 3.5, a water pumping control valve.
4. An intelligent monitoring system; 4.1 sensor (including pore water pressure sensor, soil pressure gauge, flow rate sensor, temperature sensor, vibration sensor, etc.) 4.2 grouting pressure gauge; 4.3, a negative pressure gauge; 4.4, intelligently monitoring the collector; and 4.5, a system monitoring platform.
5.1, slurry; 5.2, water; 5.3, a retention body and a reinforced soil body; 5.4, grouting holes; 5.5, water absorption holes; 5.6, conducting wires; 5.7, a filter screen.
Detailed Description
The present invention will be further described with reference to the following examples, but the present invention is not limited to the following examples.
Now combine the figure concrete description the utility model discloses a concrete implementation method, the figure only is the schematic diagram, only explains the utility model discloses a basic structure, the utility model discloses the example does not have the basis of inventive to research and develop for this field technical staff, all belongs to the utility model discloses a protection scope.
Example 1
Equipment selection and model installation
Manufacturing a mold groove (1.1): the mold groove (1.1) is a cuboid with the length of H, the width of B and the height of H, and a mold groove plate (1.1.1) made of organic glass with the thickness of H is spliced into a groove body, so that the grouting condition and the slurry (5.1) diffusion condition in the soil body can be observed conveniently. The joints of the side plates and the top cover plate are sealed by rubber sealing gaskets (1.1.3) and reinforced by section steel reinforcing strips (1.1.2) with higher rigidity, so that the deformation and even damage of the tank body caused by overlarge internal pressure of the tank body are prevented.
The soil body (1.2) is manufactured and filled: the experimental soil body is replaced by machine-made quartz sand and river sand, and the thickness of each fine sand layer (1.2.3) is h according to the size of the mold groove (1.1)1The water-resisting layer adopts a thickness of h2The clay water stopping layer (1.2.2) and the geomembrane (1.2.1). Adding water into sandy soil to prepare saturated fine sand, and selecting thickness h according to experiment1Filling; filling the powder fine sand to the thickness h1Then, filling the prepared clay water stopping layer (1.2.2) on the fine sand layer (1.2.3) to a thickness of h2And covering a geomembrane (1.2.1) above the red clay to form a water stopping layer. The remaining soil layer is filled in this way.
Selection of experimental equipment: the grouting pump (2.1) can adopt a self-suction slurry pump, the negative pressure pump (3.1) adopts a water suction pump, and the grouting pump (2.1), the grouting pressure controller (2.2), the pressurization box (2.3), the negative pressure pump (3.1) and the negative pressure controller (3.2) can select proper models according to the experimental scale; the embedded grouting pipe (2.5) and the embedded negative pressure pipe (3.4) both adopt the pipe with the radius of r0The end of the organic glass pipe is provided with a certain number of round grouting holes (5.4) and water absorbing holes (5.5), and the end of the embedded negative pressure pipe (3.4) is externally coated with a filter screen (5.7) for filtering sand grains and performing negative pressure drainage. The grouting pressure gauge (4.2) and the negative pressure gauge (4.3) are pressure gauges; the sensor (4.1) can be chosen to be of suitable specifications according to the needs of the experiment.
And (3) connecting the system: the sequential connection of the various systems is in accordance with the sequential connection shown in figure 1. The specific connection method comprises the following steps: utilize metal slip casting pipe (2.4) to connect grouting pump (2.1), slip casting pressure controller (2.2), pressurized box (2.3) and pre-buried slip casting pipe (2.5), all set up slip casting pressure gauge (4.2) around pressurized box, observe the pressure of slip casting in-process in the experiment of being convenient for. In the drainage control system (3), a metal negative pressure pipe (3.3) is adopted to be sequentially connected with a negative pressure pump (3.1), a negative pressure controller (3.2) and an embedded negative pressure pipe (3.4). A negative pressure gauge (4.3) is arranged between the negative pressure controller (3.2) and the mould groove (1.1) to observe the negative pressure of the drainage. Adopt wire (5.6) to be connected sensor (4.1) and intelligent monitoring collector (4.4), intelligent monitoring collector (4.4) returns system monitoring platform (4.5) with data.
Embedding of the sensor (4.1): according to the needs of experiments, a soil pressure gauge, a pore water pressure sensor, a soil pressure gauge, a flow velocity sensor, a temperature sensor, a vibration sensor and the like are respectively embedded at proper positions of the model groove (1.1) and the soil body (1.2) for monitoring relevant conditions of grouting measurement and are connected to an intelligent monitoring collector (4.4) through wires.
And installing experimental equipment and pipelines, and checking the accuracy of the test system and the tightness of the device.
(II) Experimental groups
In order to determine the influence of different experimental conditions on the grouting effect under the induced grouting method, five groups of experiments are designed aiming at the model. The first group is water injection experiments; influence of a second group of different water-cement ratios on induced grouting; the third group measures the influence of different grouting pressures on the induced grouting effect; the fourth group is the influence of different grouting time on the induced grouting effect; the fifth group is the influence of different soil layer structures on the induced grouting effect.
For the above experimental group, the following experimental preparations were made.
Second group: three groups of concentrations are prepared as c1、c2、c3The cement slurry solution of (1).
Third group: determining five sets of suitable grouting pressures P1、P2、P3、P4、P5The pressure values are different from each other.
And a fourth group: determining the grouting pressure as P1According to a third set of pressures of P1Initial grouting time t1Respectively determining two groups of initial grouting time t2、t3Wherein t is2Less than t1，t3Greater than t1。
And a fifth group: and (3) performing two groups of experiments on the silty sand layer (1.2.3) in the model by using machine-made quartz sand and river sand respectively according to the same grouting conditions.
(III) preparation of a slurry
The grouting slurry (5.1) mainly comprises a cement slurry solution and a water glass solution, and the cement slurry solution with different water-cement ratios c and the water glass solution with a certain modulus m are prepared according to experimental requirements.
The distance between the embedded grouting pipe (2.5) and the embedded negative pressure pipe (3.4) is the grouting radius R, and the grouting amount is calculated according to the determined grouting radius R
For controlling the amount of prepared slurry (5.1);
cement slurry solution: design concentration of c according to experimental grouping1、c2、c3The cement slurry solution of (1). The cement and water consumption under different concentrations is accurately calculated according to the designed concentration, and the cement slurry solution is prepared in groups and then fully stirred. The cement slurries were tested for fluidity, volume weight, and used within a half hour.
Water glass solution: and (3) accurately preparing a water glass solution with the modulus m according to the experimental needs, testing the fluidity and using as soon as possible.
(IV) Induction grouting (the experimental procedures are described in the second set of experiments here)
And (3) starting a grouting pump (2.1), pressing the slurry (5.1) out of the metal grouting pipe (2.4), turning off the grouting pump (2.1) after the concentration of the flowing slurry reaches the concentration of the stirred slurry, and connecting the metal grouting pipe (2.4) with the pre-buried grouting pipe (2.5) in the model box. The grouting control valve (2.6) of the grouting pump (2.1) is turned off, the negative pressure pump (3.1) is started, and the negative pressure controller (3.2) is adjusted until the vacuum degree reaches P'0And is maintained within a certain range.
Starting a grouting pump (2.1), opening a grouting control valve (2.6), and adjusting a grouting pressure controller (2.2) and a pressure tank (2.3) to enable a grouting pressure value to reach P1And when the slurry (5.1) reaches the negative pressure end pre-buried negative pressure pipe (3.4), the discharged slurry (5.1) is collected. Observing the condition that the negative pressure system (3) discharges the grout (5.1), continuously grouting until the consistency of the grout (5.1) is the same as that before grouting, and closing the water pumping control valve (3.5); still keeping the pipeline P1Pressure of continuously fillingThe slurry time period Δ t. And finally, the grouting control valve (2.6) is turned off, the grouting pump (2.1) and the negative pressure pump (3.1) are turned off, and the whole induction grouting is finished.
(V) realize the soil body reinforcement
After the grouting is finished, the slurry (5.1) is allowed to stand in the fine sand layer (1.2.3) for a time t4The slurry (5.1) forms a stable detention body and a reinforced soil body (5.3) in the soil body, a solid block is taken out from the soil body, and the curing time t is kept under certain conditions5And after the maintenance is finished, detecting the strength of the detention body and the reinforced soil body (5.3).
(VI) cycle test
According to the experimental grouping, the cycle test is carried out in sequence according to the test process.
Model and experimental scheme do above the utility model discloses a schematic scheme, according to the utility model provides a saturated sand reinforcing effect that the scheme obtained is better, can satisfy the construction needs basically.
Claims (4)
1. The utility model provides an induced slip casting experimental model of saturated powder fine sand layer which characterized in that, the induced slip casting experimental model of saturated powder fine sand layer includes: the system comprises a model system (1), a grouting control system (2), a negative pressure induction control system (3) and an intelligent monitoring system (4); the composition of each system is as follows:
the model system (1) comprises a model groove (1.1) and a test soil body (1.2) positioned in the model groove;
the mould groove (1.1) comprises: a model groove plate (1.1.1) made of organic glass, a model groove reinforcing bar steel (1.1.2) and a rubber sealing gasket (1.1.3);
the test soil body (1.2) comprises from bottom to top: a fine sand layer (1.2.3), a clay water stopping layer (1.2.2) and a geomembrane (1.2.1);
the grouting control system (2) comprises a grouting pump (2.1), a grouting pressure controller (2.2), a pressurization box (2.3) and a grouting control valve (2.6) which are sequentially connected, metal grouting pipes (2.4) are adopted for connection, and an embedded grouting pipe (2.5) finally connected with the metal grouting pipe (2.4) extends into a test soil body (1.2);
the negative pressure induction control system (3) comprises a negative pressure pump (3.1), a negative pressure induction drainage negative pressure controller (3.2) and a water pumping control valve (3.5) which are connected in sequence, the negative pressure induction drainage negative pressure controller, the water pumping control valve and the water pumping control valve are connected by a metal drainage pipe (3.3), and finally, a pre-buried negative pressure pipe (3.4) is connected and extends into a test soil body (1.2); or a plurality of water pumping control valves (3.5) are connected in parallel, and each parallel pipeline is connected with a pre-embedded negative pressure pipe (3.4) respectively at last and extends into the test soil body (1.2) and the water pumping control valve (3.5);
the intelligent monitoring system (4) comprises a sensor (4.1) positioned in a test soil body (1.2), a grouting pressure gauge (4.2) arranged on a pipeline of the grouting control system (2), a negative pressure gauge (4.3) arranged on a pipeline of the negative pressure induction control system (3), an intelligent detection collector (4.4) and a system monitoring platform (4.5); the sensor (4.1), the grouting pressure gauge (4.2) and the negative pressure gauge (4.3) are all connected with a system monitoring platform (4.5) through an intelligent detection collector (4.4);
the internal pre-buried slip casting pipe (2.5) and pre-buried negative pressure pipe (3.4) respectively of experimental soil, pre-buried slip casting pipe (2.5) and pre-buried negative pressure pipe (3.4), adopt the clear glass pipe, pre-buried slip casting pipe (2.5) pipe end sets up the circular injected hole of a certain amount, outwards sprays the slip casting thick liquid under high-pressure state, set up the circular filtration pore of a certain amount at pre-buried negative pressure pipe (3.4) pipe end, the outsourcing filter screen filters the grains of sand and carries out the negative pressure drainage.
2. The induction grouting experimental model for the saturated fine sand layer according to claim 1, wherein the sensors (4.1) comprise a pore water stress sensor, a temperature sensor, a soil pressure sensor and a flow velocity sensor.
3. The experimental model for the induced grouting of the saturated fine sand layer according to the claim 1, characterized in that the model groove is formed by splicing transparent organic glass steel plates (1.1.1), and is fixedly connected by section steel reinforcing bars (1.1.2) to prevent the model groove from deforming, and a rubber gasket (1.1.3) seals the upper opening of the model groove; soil body fine sand layers for the test are filled in the model grooves in a layered mode, machine-made quartz sand or river sand is adopted respectively, and clay water stopping layers (1.2.2) and geomembranes (1.2.1) are adopted between the layers to stop water in a layered mode.
4. The experimental model for the induction grouting of the saturated fine sand layer according to claim 1, wherein the model system comprises: the model system comprises a model groove and a soil body, and the whole grouting experiment is completed in the model system; in order to observe the flowing condition, the grouting process and the grouting effect of slurry (5.1) and water (5.2) in the experimental tank, the tank body of the model tank (1.1) is manufactured by adopting a transparent organic glass plate (1.1.1) according to the sand particle size and the slurry (5.1) particle size and determining the proportion and the grouting parameters of the model according to a similar law, the tank body is L in length, B in width and H in height, and the specific size of the tank body accords with the similar proportion.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113049452A (en) * | 2021-04-15 | 2021-06-29 | 中国水利水电科学研究院 | Device and method for measuring and controlling diffusion range of cement-based grout in grouting of covering layer |
| CN113339058A (en) * | 2021-06-24 | 2021-09-03 | 中国矿业大学 | Fluidized gangue layer adjacent surface subsequent filling system and method |
| CN113569398A (en) * | 2021-07-19 | 2021-10-29 | 湖南农业大学 | Grouting process simulation method and system and readable storage medium |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113049452A (en) * | 2021-04-15 | 2021-06-29 | 中国水利水电科学研究院 | Device and method for measuring and controlling diffusion range of cement-based grout in grouting of covering layer |
| CN113339058A (en) * | 2021-06-24 | 2021-09-03 | 中国矿业大学 | Fluidized gangue layer adjacent surface subsequent filling system and method |
| CN113569398A (en) * | 2021-07-19 | 2021-10-29 | 湖南农业大学 | Grouting process simulation method and system and readable storage medium |
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