CN205506571U - Ground water level dynamic change's foundation ditch model test device can simulate - Google Patents

Abstract

The utility model discloses a foundation pit model test device capable of simulating the dynamic change of underground water level. The device includes model boxes, water tanks, retaining walls and inner supports. The model box is composed of the model box frame, tempered glass, the bottom plate of the model box, the reaction plate, the top frame and the base of the model box; the water tank is set on the upper right of the model box to control and observe the water level change in the soil; the soil retaining The wall is erected in the model box through the retaining wall bracket, and the internal support can be installed on it; the internal support is pressed against the reaction force plate, and the reaction force plate provides the support reaction force; the response of the foundation pit to the change of groundwater after the excavation is simulated , to monitor changes in earth pressure and pore water pressure, and to explore the changes in force and deformation of the foundation pit after excavation. The utility model has a reasonable structure and is easy to operate, and can be used to simulate the influence of the dynamic change of the groundwater level on the force and deformation of the foundation pit under the most dangerous excavation conditions, and provides an effective means for related foundation pit excavation model tests and researches .

Description

A foundation pit model test device capable of simulating dynamic changes in groundwater levels

technical field

The utility model relates to a model test device for foundation pits, in particular to a model test device for foundation pits in the most dangerous working condition of dynamic changes in groundwater levels, which can be used to measure soil pressure and pore water pressure in foundation pits caused by dynamic changes in groundwater levels etc. response.

Background technique

In recent years, with the rapid development of urban construction, the number of deep foundation pit projects is increasing day by day. The foundation pit projects are facing new trends of deep depth, large scale and complex surrounding environment. Especially in the coastal and riverside areas, deep foundation pit projects are faced with challenges such as rich groundwater, complex construction environment, and difficult construction. Among them, the deformation and instability of foundation pits caused by groundwater are constantly increasing in the design and construction of deep foundation pits. highly concerned and valued. Using the method of indoor geotechnical model test to simulate the excavation of foundation pit has been widely used in the field of geotechnical engineering, but how to objectively and accurately simulate the water and soil pressure response of foundation pit under the dynamic change of groundwater through foundation pit model test is still an urgent need. solved problem.

At present, dry sand is mostly used for foundation pit model tests, and the influence of groundwater is not considered for the time being. The soil pressure of foundation pit excavation soil and the deformation of foundation pit are mainly studied, but this kind of research is not applicable to foundation pit excavation under the action of groundwater. Dig the situation. Considering the effect of constant phreatic level on the foundation pit model test, there are studies (Peng Shuquan. Macro-microscopic study on the failure mechanism of sand retaining wall [D]. Tongji University, 2007.) The method of connecting the retaining wall by applying epoxy resin after the film passes through the corona Soil walls and model boxes, this method can obtain the data of ultra-static pore water pressure, earth pressure and foundation pit deformation in the test soil, but the film corona process is more complicated, and the film may tear during the moving process when the retaining wall has a large displacement Or due to the damage caused by the friction of soil particles, it is impossible to successfully complete the test or repeat the test. Considering the impact of groundwater level changes on foundation pit model tests, there are studies (Sun Wei. Experimental and theoretical research on the behavior of deep foundation pits in coastal areas [D]. Zhejiang University, 2015.) The method of fixing retaining walls is used, which can only Obtaining the change of the excess static pore water pressure in the soil cannot obtain accurate data on the change of the earth pressure and the deformation of the foundation pit, which is still quite different from the response of the actual foundation pit project under the action of the dynamic groundwater level. Therefore, more convenient and accurate simulation of groundwater dynamic changes and movable retaining walls are the main problems to be solved in the model tests of excavation of foundation pits along the sea and along the river.

A large number of experimental studies have shown that the completion of foundation pit excavation (excavation to the bottom of the foundation pit) is generally the most dangerous condition of foundation pit excavation. In actual engineering, the excessive deformation or instability and damage of many foundation pits often occur when the excavation of the foundation pit is completed. Therefore, the water and soil pressure and deformation response under the condition of foundation pit excavation will become the top priority in the model test research.

Contents of the invention

In order to overcome the deficiencies of the prior art above, the utility model provides a foundation pit model test device that can simulate the dynamic change of the groundwater level, which solves the problem of effectively and accurately controlling the dynamic change of the groundwater level and measuring the earth pressure under the most dangerous working conditions of the foundation pit , Pore water pressure, and determine the development law of the stress and deformation of the foundation pit.

The technical solution adopted by the utility model to solve the technical problem is: a foundation pit model test device capable of simulating the dynamic change of the groundwater level, including four parts: a model box, a water tank, a retaining wall and an inner support; the model box is composed of The model box frame, tempered glass, model box bottom plate, reaction plate, top frame and model box base are composed; the front and rear sides of the model box frame are equipped with toughened glass, which is convenient for observing the displacement of the retaining wall and the foundation pit soil during the test The deformation of the model box is fixed at the bottom; the reaction plate is set on the left side of the model box, the reaction plate and the model box frame are fixed on the base of the model box, and the top is connected by the top frame; the water tank is connected by a belt Hole aluminum plate, bar-shaped aluminum plate, water tank bracket, water tank bracket fixing screw and scale, which are erected on the upper right of the model box through the water tank bracket, used to control and observe the water level change in the soil; the belt water hole The anti-filter geotextile is pasted on the surface of the aluminum plate to prevent the loss of the test soil during the water level change; the scale is pasted on the tempered glass and can be used to directly observe and record the water level change; the upper part of the retaining wall is made of The wall fixing bolts are connected to the retaining wall bracket, and water-stop rubber strips are installed on both sides, and the retaining wall is erected in the model box through the retaining wall bracket; the inner support is composed of a solid aluminum rod and an inner support fixing bolt; the solid aluminum The rod can be installed on the retaining wall through the inner bolt hole at one end and the inner support fixing bolt, and the other end is pressed against the reaction plate, and the reaction force is provided by the reaction plate; the valve connected to the water tank is installed on the right side of the model box , used to control the rise and fall of the water level in the water tank. The test soil is poured into the excavation state of the foundation pit and fully saturated, and the pre-buried earth pressure sensor and pore water pressure sensor are used to monitor the response of the soil pressure and pore water pressure of the foundation pit under the dynamic change of the groundwater level. The displacement sensor monitors the displacement of the retaining wall and the deformation of the foundation pit soil.

Further, the model box frame is welded by 10mm thick stainless steel bars and stainless steel plates; the tempered glass is installed on the inside of the model box frame by construction glue; the bottom plate of the model box is 10mm thick stainless steel plate; the The counter force plate is a 10mm thick stainless steel plate; the top frame is welded by a 20mm thick stainless steel bar; the base of the model box is welded by an I-beam; The simulated retaining wall stiffness is calculated; the retaining wall support is a 20mm thick strip aluminum plate; the valve is a copper core valve.

Further, the model box frame and the reaction plate are fixed to the model box base by spot welding around them.

Further, the water tank is connected to the inner wall of the model box through glass glue.

Further, the aluminum plate with water holes and the water tank support are tightly connected by fixing screws of the water tank support.

Further, the water-stop rubber strip is vertically attached to the tempered glass during the test, so as to ensure that no water leakage occurs on the contact surface with the model box during the movement of the retaining wall.

Compared with the prior art, the beneficial effects of the utility model are:

1. The water tank in the utility model is erected in the model box, and glass glue is used to seal the gap between the water tank and the model box. The aluminum plate with water holes makes the water level in the water tank communicate with the water level of the test soil, which can be adjusted by adjusting the water level in the water tank. The water level of the test soil is controlled to control the change of the water level of the test soil; the anti-filter geotextile is pasted on the surface of the aluminum plate with water holes to prevent the loss of the test soil during the change of the water level; the scale on the water tank is pasted on the tempered glass, which is convenient for direct observation and Record changes in water level.

2. The movable retaining wall is adopted in the utility model, and the thickness of the retaining wall is obtained through the conversion of the stiffness of the retaining wall simulated by the test, which is consistent with the fact that the retaining wall can be displaced and deformed in the actual project; There are water-stop rubber strips on both sides of the wall, which are tightly attached to the tempered glass on both sides of the model box, so as to ensure that the contact surface with the tempered glass does not leak during the movement of the retaining wall.

3. The inner support in the utility model is installed on the retaining wall, and the number of inner supports and the number of inner support elements of each support can be adjusted according to the needs of the model test.

Description of drawings

Fig. 1 is the side view of the foundation pit model test device that can simulate the dynamic change of groundwater level;

Fig. 2 is the top view of the foundation pit model test device that can simulate the dynamic change of groundwater level;

Fig. 3 is a schematic diagram of the symmetrical plane of the foundation pit;

Fig. 4 is a side view of the water tank;

Figure 5 is a side view of the retaining wall;

Figure 6 is a schematic diagram of retaining wall and inner support installation;

In the figure: model box 1; model box frame 1-1; tempered glass 1-2; model box bottom plate 1-3; counter force plate 1-4; top frame 1-5; model box base 1-6; water tank 2; Aluminum plate with water hole 2-1; strip aluminum plate 2-2; water tank bracket 2-3; water tank bracket fixing screw 2-4; scale 2-5; retaining wall 3; water-stop rubber strip 3-1; Retaining wall bracket 4; retaining wall fixing bolt 5; inner support 6; solid aluminum rod 6-1; inner support fixing bolt 6-2; valve 7; test soil 8.

detailed description

Below in conjunction with accompanying drawing and embodiment the utility model is further described.

As shown in Fig. 1, Fig. 2 and Fig. 3, the utility model can simulate the foundation pit model test device of the dynamic change of groundwater level, including model box 1, water tank 2, retaining wall 3 and inner support 6 four parts.

Described model box 1 is made up of model box frame 1-1, tempered glass 1-2, model box bottom plate 1-3, reaction plate 1-4, top frame 1-5 and model box base 1-6; The box frame 1-1 is welded by 10mm thick stainless steel bars and stainless steel plates; the toughened glass 1-2 is 20mm thick, and is installed on the inside of the model box frame 1-1 on both sides of the front and back of the model box 1 through construction glue; Described model box bottom plate 1-3 is the stainless steel plate of 10mm thickness; Described reaction force plate 1-4 is the stainless steel plate of 10mm thickness, is arranged on the left side of model box 1, and model box frame 1-1 is formed by the stainless steel plate of top. The top frame 1-5 is connected by spot welding around, and is fixed on the model box base 1-6 welded by I-beam through spot welding around; the top frame 1-5 is welded by 20mm thick stainless steel bars ; The water tank 2 is made of a vertically placed aluminum plate 2-1 with water holes, a horizontally placed strip aluminum plate 2-2, tempered glass 1-2 on the front and rear sides and the inner wall of the model box frame 1-1 through the glass Formed by glue connection, erected on the upper right in the model box 1 by the water tank bracket 2-3, for controlling and observing the water level change in the soil; the aluminum plate 2-1 with the water hole and the water tank bracket 2-3 are formed by The fixing screw 2-4 of the water tank bracket is tightened and connected; the surface of the aluminum plate 2-1 with a water hole is pasted with anti-filter geotextile to prevent the loss of the test soil during the water level change; the scale 2-5 is arranged on the tempered glass 1-2 can be used for direct observation and recording of water level changes; the retaining wall 3 is erected in the model box 1 through the retaining wall bracket 4, and is always kept perpendicular to the tempered glass 1-2 during the movement; the inner The support 6 is installed on the retaining wall 3 through one end of the aluminum rod 6-1, and the other end is pressed against the reaction plate 1-4, and the reaction force is provided by the reaction plate 1-4; the valve 7 is a high-quality copper core The valve, installed on the right side of the model box 1, is used to control the rise and fall of the water level in the water tank 2; the test soil 8 is obtained by pouring standard Fujian fine sand through sand rain method.

As shown in Figure 4, the water tank 2 is made up of an aluminum plate 2-1 with water holes, a strip aluminum plate 2-2, a water tank support 2-3, a water tank support fixing screw 2-4 and a scale 2-5; A large number of round water holes are arranged on the surface of the aluminum plate 2-1 with water holes to ensure that the water level in the water tank is connected and consistent with the water level of the test soil during the test, so as to control the water level of the test soil by adjusting the water level in the water tank. changes in the water level of the body.

As shown in Figure 5, grooves on both sides of the retaining wall 3 are installed with water-stop rubber strips 3-1; the water-stop rubber strips 3-1 are vertically attached to the tempered glass 1-2 during the test to ensure Water leakage does not occur at the contact surface between the retaining wall 3 and the model box 1 during the moving process; the retaining wall 3 is an aluminum plate of a certain thickness, and its thickness is calculated by the stiffness of the retaining wall simulated by the test; the retaining wall support 4 is 20mm thick strip aluminum plate.

As shown in Figure 6, the solid aluminum rod 6-1 can be connected and installed on the retaining wall 3 through the inner bolt hole at one end and the inner support fixing bolt 6-2; the diameter of the solid aluminum rod 6-1 is determined by the test The stiffness of the simulated inner support is calculated.

The working process of the utility model is as follows: first, the retaining wall 3 and the retaining wall bracket 4 are connected through the retaining wall fixing bolt 5, and then the inner bolt at one end of the solid aluminum rod 6-1 and the inner supporting fixing bolt 6-2 The inner support 6 is installed on the retaining wall 3; the retaining wall 3 with the inner support 6 installed is erected in the model box 1 through the retaining wall bracket 4, so that the inner support 6 is pressed against the reaction force plate 1-4, and the retaining wall 3 The earth wall 3 is vertically attached to the tempered glass 1-2; then the earth pressure sensor required for monitoring the earth pressure is installed on the retaining wall 3; The height difference between the mesh and the surface of the test soil is used to obtain the soil compactness required for the model test; the test soil 8 is poured into the foundation pit excavation completion condition as shown in Figure 1, and the valve 7 is directed to the model box. 1 Inject water to saturate the test soil 8, and strictly control the water injection speed of the valve 7 to reduce the loss of the test soil (do not scour the test soil in the foundation pit). ) slowly drains (clear) water from the area above the model box; after the test soil 8 is fully saturated, a pore water pressure sensor is buried in the borehole, and the borehole soil is backfilled; The displacement sensor monitors the displacement of the retaining wall 3 and the deformation of the foundation pit soil respectively; after the above-mentioned test preparations are completed, the water level change shown by the scale 2-5 in the water tank 2 is controlled by the valve 7 to realize the groundwater level dynamics of the foundation pit Changes, collecting the soil pressure and pore water pressure changes of the foundation pit caused by the dynamic change of the groundwater level, recording the displacement of the retaining wall and the deformation of the foundation pit soil, and obtaining the water and soil pressure response of the foundation pit caused by the change of the groundwater level, the displacement of the retaining wall and The law of foundation pit deformation and so on.

Claims (6)

1. one kind can the excavation models assay device that dynamically changes of simulated groundwater position, it is characterised in that include model casing (1), Water tank (2), retaining wall (3) and (6) four parts of inner support；Described model casing (1) is by model casing framework (1-1), steel Change glass (1-2), model casing base plate (1-3), reaction plate (1-4), top frame (1-5) and model casing base (1-6) composition； Before and after described model casing framework (1-1), safety glass (1-2), bottom fixed model box plate (1-3) are installed in both sides；Described Reaction plate (1-4) is arranged on the left side of model casing (1), and reaction plate (1-4) and model casing framework (1-1) are each attached to model On bottom seat (1-6), top is connected by top frame (1-5)；Described water tank (2) is by the aluminium sheet (2-1) of band limbers, bar Shape aluminium sheet (2-2), tank bracket (2-3), tank bracket fixed screw (2-4) and rule (2-5) composition, pass through water tank Support (2-3) is erected at the upper right side in model casing (1)；Aluminium sheet (2-1) the surface mount anti-filter geotechnique of described band limbers Fabric；Described rule (2-5) is pasted onto on safety glass (1-2)；The top of described retaining wall (3) is fixed by retaining wall Bolt (5) connects retaining wall support (4), and watertight rubber bar (3-1) is installed in both sides, and retaining wall (3) passes through retaining wall support (4) it is erected in model casing (1)；Described inner support (6) is fixed bolt (6-2) by solid aluminum bar (6-1) and inner support Composition；Described solid aluminum bar (6-1) is fixed bolt (6-2) by the Inner bolt holes of one end and inner support and is connected and installed in gear soil On wall (3), the other end holds out against reaction plate (1-4)；The valve (7) of joining water box (2) is installed on the right side of described model casing (1).

The most according to claim 1 a kind of can the excavation models assay device that dynamically changes of simulated groundwater position, its feature exists In, described model casing framework (1-1) is welded by rustless steel steel bar thick for 10mm and stainless-steel sheet；Described safety glass (1-2) it is arranged on model casing framework (1-1) inner side by building glue；Described model casing base plate (1-3) is that 10mm is thick Stainless-steel sheet；Described reaction plate (1-4) is the stainless-steel sheet that 10mm is thick；Described top frame (1-5) is by 20mm thickness Rustless steel steel bar is welded；Described model casing base (1-6) is welded by I-steel；Described retaining wall (3) is aluminium sheet； Described retaining wall support (4) is the strip aluminium sheet that 20mm is thick；Described valve (7) is copper core valve.

The most according to claim 1 a kind of can the excavation models assay device that dynamically changes of simulated groundwater position, its feature Being, described model casing framework (1-1) and reaction plate (1-4) are fixed on model casing base (1-6) by surrounding spot welding.

The most according to claim 1 a kind of can the excavation models assay device that dynamically changes of simulated groundwater position, its feature It is, the described water tank (2) inwall by glass cement connection mode molding box (1).

The most according to claim 1 a kind of can the excavation models assay device that dynamically changes of simulated groundwater position, its feature Being, aluminium sheet (2-1) and the tank bracket (2-3) of described band limbers are tightened connection by tank bracket fixed screw (2-4).

The most according to claim 1 a kind of can the excavation models assay device that dynamically changes of simulated groundwater position, its feature Being, described watertight rubber bar (3-1) is vertical with safety glass (1-2) in process of the test to be adjacent to.