CN106248495A - The indoor long-term assay device of post grouting pile of simulated groundwater flowing and test method thereof - Google Patents

Abstract

The invention discloses an indoor long-term test device for post-grouting piles for simulating groundwater flow, which includes a test box and a dynamic water simulation device for injecting water into the test box to simulate groundwater flow. The test box is built with simulated piles. The lower end of the pile is provided with a grout hole, and the upper end of the simulated pile is connected with a grouting device for pouring cement slurry; the test box is provided with a lever frame, one end of which is rotatably connected to the test box, and the other end is suspended in the air. The free end is connected with a weight loading device. The indoor long-term test device of the post-grouting pile for simulating groundwater flow solves the post-grouting bearing test under the simulated groundwater flow condition, and can fully understand the actual grouting process and the setting rate of the cement grout after the grouting is completed, and the amount of cement grout can be specified And cost saving; secondly, through the indoor long-term test of post-grouting piles simulating groundwater flow, the law of long-term bearing performance of grouting piles can be revealed, so that post-grouting technology can be more perfect.

Description

Indoor long-term test device and test method of post-grouting piles for simulating groundwater flow

technical field

The invention relates to a grouting pile test device and a test method in the field of civil engineering, in particular to an indoor long-term test device and a construction method of a post-grouting pile simulating groundwater flow.

Background technique

Post-grouting technology plays an important role in improving the bearing capacity of pile foundations. Many scholars at home and abroad have done corresponding indoor test analysis and research on the bearing mechanism of post-grouting piles, and obtained a series of fruitful theoretical and practical application results. However, most post-grouting theories are based on no groundwater or static groundwater obtained under the conditions. There are two ways for the formation of groundwater. One is that groundwater forms dynamic water due to the flow of water due to the difference in water head in the area; the other is that groundwater leaks and forms dynamic water due to defects and damages in waterproof curtains or waterproof structures. . Therefore, solving the problem of grouting effect under the condition of groundwater flow has become the key to improving the bearing capacity of pile foundations. There are few researches on grouting theory under the condition of groundwater flow. Most of the researches on grouting theory after indoor model piles do not consider the groundwater or the groundwater static condition, but the diffusion of grout under the groundwater static condition and the groundwater flow condition. The law and diffusion mechanism are very different. It is unreasonable to use the conclusions obtained from the model test under the condition of groundwater static to guide the practice of grouting engineering under the condition of groundwater flow. study in depth.

Therefore, urgently need to solve the above-mentioned problem.

Contents of the invention

Purpose of the invention: The first purpose of the present invention is to provide a long-term indoor test device for post-grouting piles that can fully understand the grouting process and the coagulation rate of the cement slurry after the grouting is completed, and clearly determine the amount of cement slurry used to simulate groundwater flow.

Another object of the present invention is to provide a test method for the indoor long-term test device of post-grouting piles for simulating groundwater flow.

Technical solution: In order to achieve the above purpose, a long-term indoor test device for post-grouting piles for simulating groundwater flow according to the present invention includes a test box and a dynamic water simulation device for injecting water into the test box to simulate groundwater flow. There is a simulation pile built in the test box, and a grout hole is opened at the lower end of the simulation pile, and a grouting device for pouring cement slurry is connected to the upper end of the simulation pile; a lever frame is provided on the test box, and one end of the lever frame is connected to the test The box is rotatably connected, and the other end is suspended, and a weight loading device is connected to the suspended end.

Wherein, the dynamic water simulation device includes a water collection tank externally connected to a water source and a height-adjustable support for fixing the water collection tank. A water outlet is provided, and the water outlet injects water into the test chamber through the water inlet pipe; the flow at the water source is controlled so that the amount of water flowing into the water collecting tank is greater than the water flowing into the test chamber, and the excess water overflows from the top of the water collecting tank into the water collecting pan, and Flow out from the overflow port to stabilize the water level in the test chamber.

Preferably, the grouting device includes a mixing tank, a grout suction pipe, a grouting pump and a grouting pipe connected in sequence, and a grouting pressure gauge is also provided on the grouting pipe.

Further, the upper end of the simulated pile is connected with a tee joint, one end of the tee joint is connected with the grouting pipe in the grouting device, one end is connected with the grouting pipe above the simulated pile, and the other end is connected with the grouting device ; And the grouting pipe 26 is provided with a grouting valve.

Preferably, the slurry return device includes a slurry storage barrel and a slurry return pipe, one end of the slurry return pipe extends into the slurry storage barrel, and the other end is connected with a three-way joint; the slurry return pipe is also provided with a slurry return valve and return slurry pressure gauge.

Further, the weight loading device is a weight basket that can add or remove weights at will.

The present invention is a kind of test method of indoor long-term test device of post-grouting pile for simulating groundwater flow, comprising the following steps:

(1) Fill the soil sample into the test box and carry out layered compaction until the design height, and the model pile can be embedded in the soil sample or driven into the soil sample;

(2) Dynamic water simulation operation: Connect the water collection tank to the test chamber through the water inlet pipe, control the flow at the water source so that the water flow into the water collection tank is greater than the water flow into the test chamber, and the excess water flow overflows from the top of the water collection tank into the water collection pan. And flow out from the overflow port, so that the water flow rate of the water collection tank reaches the design value, and the water level in the test box is stable;

(3) Grouting operation: The grouting pipe, the grouting pipe and the grouting pipe are connected to form a loop by using a three-way joint. Open the slurry return valve to the maximum first, so that all the slurry returns to the slurry storage tank, and then slowly close the slurry return valve, so that the reading of the pressure gauge reaches the required slurry pressure, and then open the slurry valve to adjust the pressure. The grouting valve keeps the pressure basically stable at the grouting pressure value; grouting is performed on the model pile, and the grouting time, grouting amount, grouting pressure and grouting flow rate are recorded during the grouting process;

(4) Long-term loading operation: After the grouting is completed and the strength is reached, the bearing capacity test of the model pile is carried out by increasing the weight of the weight loading device on the lever frame, and the displacement change of the pile top is continuously observed at different times to detect the groundwater flow condition The grouting effect of the lower grouting pile.

Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: firstly, the indoor long-term test device of the post-grouting pile for simulating groundwater flow solves the post-grouting bearing test under the simulated groundwater flow condition, and can fully understand the actual pressure The grouting process and the coagulation rate of the cement grout after the grouting are completed to clarify the amount of cement grout and save costs; secondly, through the long-term indoor test of the post-grouting pile that simulates the flow of groundwater, the law of the long-term bearing performance of the grouting pile can be revealed, so that the future The grouting technology is more perfect, which is convenient to improve the bearing capacity of the pile foundation, so that it can be better used in actual engineering construction; moreover, the test device solves the problems of dynamic water source simulating the flow of groundwater, stable water head and adjustable head height. The key problem is to solve the key problems of reducing the fluctuation of grouting pressure, protecting the precision pressure gauge and adjusting the grouting pressure; finally, the test device is simple in process, easy to operate, safe, reliable, economical and applicable, and is convenient for popularization and application.

Description of drawings

Fig. 1 is a structural representation of the present invention;

Fig. 2 is the top view of water collecting tank in the present invention;

Fig. 3 is the sectional view of water collecting tank in the present invention;

Fig. 4 is the structural representation of grouting device among the present invention;

Fig. 5 is a schematic structural view of a slurry returning device in the present invention;

Fig. 6 is a top view of the lever frame part in Fig. 1;

Fig. 7 is a partial schematic diagram of the lever frame part in Fig. 1 .

detailed description

The technical solution of the present invention will be further described below in conjunction with the accompanying drawings.

As shown in Figure 1, a long-term indoor test device for post-grouting piles simulating groundwater flow in the present invention includes a test box 1, a dynamic water simulation device 2, a simulated pile 3, a grouting hole 4, a grouting device 5, and a lever frame 6 And weight loading device 7. The bottom of the test box 1 has a water outlet pipe 27 . Fill the soil (rock) body into the test box 1, fill it in layers and compact it appropriately, and the model piles can be buried in the sand filling or driven into the test box after sand filling. Water flow is injected into the test chamber 1 through the dynamic water simulation device 2 to simulate groundwater flow. The upper end of the simulation pile 3 is connected to a grouting device 5 for pouring cement slurry, and the lower end of the simulation pile 3 is provided with a grout hole 4 . The above-mentioned test box 1 is provided with a lever frame 6, one end of the lever frame 6 is rotatably connected with the test box 1, and the other end is suspended in the air, and a weight loading device 7 is connected to the suspended end, and the weight loading device 7 can be increased at will. Weight basket for minus weights.

As shown in Fig. 6 and Fig. 7, the present invention adopts grouting device 5 to carry out grouting to simulated pile, carries out bearing capacity test after grouting is finished and reaches design strength, utilizes lever frame 6 and weight loading device 7 to model pile 3 Carry out long-term bearing performance testing. Weld the lever frame 6 on the test box 1, take the cushion block 29 on the lever frame 6 as the base point, weld one end of the lever on the rotating shaft 28 of the test box, and place the weight in the weight basket hanging from the other end of the lever frame , using the principle of leverage for loading, the loading weight is equal to the weight of the weight multiplied by the torque, which is convenient for long-term test loading. The model pile 3 is located under the lever frame 6. By increasing the weight, the lever frame 6 exerts pressure on the spacer 29, thereby acting on the model pile 3, and a long-term loading test can be performed on the grouted pile.

As shown in Figure 2 and Figure 3, the above-mentioned dynamic water simulation device 2 includes a water collection tank 8 connected to an external water source and a height-adjustable support 9 for fixing the water collection tank 8, and the height of the support 9 in the vertical direction can be adjusted arbitrarily .

The outer ring of the water collection box 8 is provided with a water collection tray 11 with an overflow port 10 at the bottom, and a water outlet 12 is provided at the bottom of the water collection box 8, and the water outlet 12 injects water into the test chamber 1 through a water inlet pipe 13; wherein the water source The water flows into the water collection tank 8 through the water pipe, and the water pipe is provided with a flow valve. By adjusting the flow valve to control the flow, the water flow into the water collection tank is greater than the water flow into the test chamber 1, and the excess water flow overflows from the top of the water collection tank 8 and enters the water collection pan. 11, and flow out from the overflow port 10 to stabilize the water level in the test chamber.

The present invention first flows the water at the water source into the water collecting tank 8 to make the water collecting tank 8 full, then opens the valve of the water collecting tank 8 to allow the water in the water collecting tank 8 to flow into the test chamber 1 through the water inlet pipe 13, and adjust the water quantity at the water source to make the water flow into the test chamber 1. The water yield of the water collecting tank 8 is slightly greater than the water yield flowing into the test chamber 1, then the excess water overflows from the top of the water collecting tank 8 and enters the water collecting pan 11, then flows out from the overflow port 10 of the water collecting pan 11, and the water flowing out of the overflow port 10 makes the water collecting tank The water level of the water tank 8 is stabilized at a certain set height, and the water volume of the water inlet of the water collection tank 8 is slightly larger than the water volume of the water outlet 12, so that the water level in the test chamber 1 is stabilized, and the flow rate of the water flowing into the test chamber 1 is controlled, so that it can simulate Effect of steady groundwater flow on post-grouted piles.

In order to provide a stable water flow rate during the test, it is necessary to provide a stable water head height. At the same time, different water flow velocity can be simulated by adjusting the height support, that is, the influence of different groundwater flow velocity on the post-grouting pile can be simulated.

As shown in Figure 4, the above-mentioned grouting device 5 includes a mixing tank 14, a grouting pipe 15, a grouting pump 16 and a grouting pipe 17 connected in sequence, and the grouting pipe 17 is also provided with a grouting valve 18 and a grouting valve 18. pressure gauge 19.

As shown in FIG. 1 , a tee joint 20 is connected to the upper end of the simulation pile 3 , one end of the tee joint 20 is connected with the grout delivery pipe 17 in the grouting device 5 , and the other end is connected with the grout return device 21 . The slurry return device 21 includes a slurry storage tank 22 and a slurry return pipe 23. One end of the slurry return tube 23 extends into the slurry storage tank 22, and the other end is connected with the tee joint 20; Slurry valve 24 and return slurry pressure gauge 25, as shown in Figure 5.

The present invention is a kind of test method of indoor long-term test device of post-grouting pile for simulating groundwater flow, is characterized in that, comprises the following steps:

(1) Fill the soil sample into the test chamber 1, and carry out layered compaction until the design height, and the model pile 3 can pre-embed the soil sample or drive it into the soil sample;

(2) Dynamic water simulation operation: Connect the water collection tank 8 to the test chamber 1 through the water inlet pipe 13, control the flow at the water source so that the amount of water flowing into the water collection tank is greater than the water flow into the test chamber 1, and the excess water flow overflows from the top of the water collection tank 8 Enter the water collection tray 11, and flow out from the overflow port 10, so that the water flow rate of the water collection tank 8 reaches the design value, and the water level in the test chamber 1 is stable;

(3) Grouting operation: the grouting pipe 17, the grouting pipe 23 and the grouting pipe 26 are connected by a tee joint 20 to form a circuit, and the grouting pipe 26 and the grouting pipe 23 are respectively provided with a grouting valve 18 and the slurry return valve 24, when grouting, firstly open the slurry return valve 24 to the maximum, so that all the slurry returns to the slurry storage tank 22, and then slowly close the slurry return valve 24, so that the reading of the pressure gauge reaches the required grouting Then open the grouting valve 18, adjust the grouting valve 18 so that the pressure is basically stable at the grouting pressure value, reduce the fluctuation of the grouting pressure and protect the precision pressure gauge; Record the grouting time, grouting volume, grouting pressure and slurry flow rate during the process;

(4) Long-term loading operation: After the grouting is completed and the strength is reached, the bearing capacity test of the model pile 3 is carried out by increasing the weight of the weight loading device 7 on the lever frame, and the displacement changes of the pile top are continuously observed at different times to detect groundwater Grouting effect of grouting piles under flow conditions.

Claims (7)

1. a long-term indoor test device for grouting piles after simulating groundwater flow, characterized in that: comprise test chamber (1) and the dynamic water simulation device (2) that injects water flow into simulated groundwater flow in this test chamber (1), The test box (1) has a built-in simulation pile (3), the lower end of the simulation pile (3) is provided with a grout hole (4), and the upper end of the simulation pile (3) is connected with a grouting device for pouring cement slurry (5); said test box is provided with a lever frame (6), one end of the lever frame (6) is rotatably connected with the test box (1), the other end is suspended, and the suspended end is connected with a weight loading device (7 ). 2. the indoor long-term test device of post-grouting piles for simulating groundwater flow according to claim 1, characterized in that: said dynamic water simulation device (2) includes a water collection box (8) connected to an external water source and a water collection box (8) for fixing the collection box. The height-adjustable support (9) of the water tank (8), the outer ring of the water collecting tank (8) is provided with a water collecting pan (11) with an overflow opening (10) at the bottom, and the bottom of the water collecting tank (8) is provided with The water outlet (12), the water outlet (12) injects water flow into the test chamber (1) through the water inlet pipe (13); wherein the flow rate at the water source is controlled so that the water flow into the water collection tank is greater than the water flow into the test chamber (1), excessive The water flow overflows from the top of the water collection tank (8) into the water collection tray (11), and flows out from the overflow port (10), so that the water level in the test chamber (1) is stabilized. 3. The indoor long-term test device of post-grouting piles for simulating groundwater flow according to claim 1, characterized in that: said grouting device (5) comprises a mixing tank (14) connected in sequence, a grouting pipe (15) , a grouting pump (16) and a slurry delivery pipe (17), which is also provided with a slurry delivery pressure gauge (19) on the slurry delivery pipe (17). 4. the post-grouting pile indoor long-term test device for simulating groundwater flow according to claim 3, is characterized in that: the upper end of the simulated pile (3) is connected with a tee joint (20), and the tee joint (20) One end is connected with the grouting pipe (17) in the grouting device (5), one end is connected with the grouting pipe (26) above the simulated pile (3), and the other end is connected with the grouting device (21); and The grouting pipe (26) is provided with a grouting valve (18). 5. The indoor long-term test device of post-grouting piles for simulating groundwater flow according to claim 4, characterized in that: the grout return device (21) includes a grout storage tank (22) and a grout return pipe (23), the One end of the return pipe (23) extends into the pulp storage tank (22), and the other end is connected with the tee joint (20); the return pipe (23) is also provided with a return valve (24) and a return Pressure gauge (25). 6. The indoor long-term test device for post-grouting piles for simulating groundwater flow according to claim 4 or 5, characterized in that: the weight loading device (7) is a weight basket that can increase or decrease weight at will. 7. according to the test method of the indoor long-term test device of the back grouting pile of the arbitrary described simulation groundwater flow of claim 1-6, it is characterized in that, comprises the steps: (1) Fill the soil sample into the test box (1), and carry out layered compaction until the design height, and the model pile (3) can pre-embed the soil sample or drive it into the soil sample; (2) Dynamic water simulation operation: Connect the water collection tank (8) to the test chamber (1) through the water inlet pipe (13), and control the flow at the water source so that the amount of water flowing into the water collection tank is greater than the amount of water flowing into the test chamber (1). The water flow overflows from the top of the water collection box (8) into the water collection tray (11), and flows out from the overflow port (10), so that the flow rate of the water outlet from the water collection box (8) reaches the design value, and the water level in the test chamber (1) is stable; (3) Grouting operation: use a three-way joint (20) to connect the grout delivery pipe (17), the grout return pipe (23) and the grouting pipe (26) to form a circuit, and the grouting pipe (26) and the grout return A grouting valve (18) and a grouting valve (24) are respectively arranged on the pipe (23). When grouting, the grouting valve (24) is first opened to the maximum so that all the grout is returned to the grout storage tank (22). Then slowly close the grouting valve (24) to make the reading of the pressure gauge reach the required grouting pressure, then open the grouting valve (18) and adjust the grouting valve (18) to make the pressure basically stable at the grouting pressure value ; The model pile (3) is grouted, and the grouting time, the grouting amount, the grouting pressure and the grouting fluid velocity are recorded during the grouting process; (4) Long-term loading operation: After the grouting is completed and the strength is reached, the bearing capacity test of the model pile (3) is carried out by increasing the weight of the weight loading device (7) on the lever frame, and the displacement change of the pile top is continuously observed at different times In this case, the grouting effect of the grouting pile is tested under the condition of groundwater flow.