Construction method for sinking a caisson with the aid of steel sheet piles

Abstract

This invention discloses a construction method for sinking a caisson using sheet piles, comprising the following steps: after the caisson construction is completed, an annular mud pit is excavated around the caisson, extending inward to the outer wall of the caisson; mud is prepared in the annular mud pit; water is injected into the caisson to soften the soil inside; sheet piles are driven vertically downward from the annular mud pit, with the bottom elevation of the sheet piles lower than the bottom elevation of the cutting edge of the caisson; after the sheet piles are driven into place, they are pulled out, allowing the mud to flow into the pile pit formed by the pulled-out sheet piles; the above steps are repeated to allow the caisson to sink to the designed position; after the caisson has sunk to the designed position, the accumulated water in the caisson is pumped out, and the annular mud pit and the pile pit are backfilled. This construction method improves construction efficiency.

Description

Technical Field

[0001] This invention relates to the field of building construction, and in particular to a construction method using steel sheet piles to assist in the sinking of caissons. Background Technology

[0002] In traditional caisson sinking construction, after the caisson is constructed, the surrounding soil is protected by foundation pit support. Then, the soil at the bottom of the cutting edge is excavated inside the caisson to suspend the bottom of the cutting edge as much as possible, allowing the caisson to sink due to its own weight. However, this method is not suitable for all strata. In some strata with high soil pressure, even if the soil at the bottom of the cutting edge of the caisson is excavated, the lateral pressure and static friction of the soil are too great, causing the caisson to be suspended in mid-air and unable to sink. In this case, it is necessary to drive pipes around the caisson to fire air cannons at the soil around the caisson to break up the soil around the caisson so that the caisson can sink further. This caisson sinking method has poor practicality and low construction efficiency. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a construction method for sinking caissons with the assistance of steel sheet piles. This method is applicable to caisson sinking in various strata and does not require multiple types of machinery to assist in caisson sinking, thus saving production costs.

[0004] To achieve the above objectives, the technical solution adopted by this invention is a construction method for caisson sinking assisted by steel sheet piles, comprising the following steps:

[0005] Step 1: After the caisson construction is completed, an annular mud pit is excavated around the caisson, extending inward to the outer wall of the caisson, and mud is prepared in the annular mud pit.

[0006] Step 2: Inject water into the caisson to soften the soil inside the caisson;

[0007] Step 3: Drive steel sheet piles vertically downward from the annular mud pit, so that the bottom elevation of the steel sheet piles is lower than the bottom elevation of the cutting edge of the caisson;

[0008] Step 4: After the sheet pile is driven into place, pull it out and let the mud flow into the pile pit formed by pulling out the sheet pile.

[0009] Step 5: Repeat steps 3 and 4 above to allow the caisson to sink to the designed position;

[0010] Step 6: After the caisson has sunk to the designed position, the water inside the caisson is pumped out and the annular mud pit and pile pit are backfilled.

[0011] The further improvement of the construction method of using sheet piles to assist in the sinking of the caisson in this invention is that, in step 3, two sheet piles are driven vertically downwards symmetrically from the annular mud pit with the axis of the caisson as the axis of symmetry, so that the bottom elevation of the two sheet piles is lower than the bottom elevation of the cutting edge of the caisson.

[0012] A further improvement of the construction method of using sheet piles to assist in caisson sinking is that, in step 5, the driving points of the two sheet piles are moved clockwise or counterclockwise along the annular mud pit.

[0013] The further improvement of the construction method of using sheet piles to assist in the sinking of the caisson in this invention is that, during step 5, a level instrument is used to monitor whether the settlement of the caisson is uniform. When uneven settlement of the caisson is detected, the insertion and extraction of the sheet piles on the side with larger settlement is stopped, and the sheet piles are inserted and extracted in a concentrated manner on the side with smaller settlement, so that the caisson maintains uniform settlement.

[0014] The further improvement of the construction method of using sheet piles to assist in the sinking of the caisson in this invention is that, in step 3, a sheet pile is driven vertically downward from the annular mud pit; and in step 5, the driving point of the even-numbered sheet pile is symmetrically set with respect to the axis of the caisson with respect to the driving point of the previous sheet pile.

[0015] The further improvement of the construction method of using sheet piles to assist in caisson sinking in this invention is that, during the execution of step 5, a level instrument is used to monitor the unilateral settlement of the caisson caused by each insertion and extraction of sheet piles, and when the sheet piles are inserted and extracted for the even-numbered time, the insertion depth and speed are controlled based on the unilateral settlement of the previous time, so that the unilateral settlement of the two times are the same.

[0016] A further improvement of the construction method of using sheet piles to assist in sinking a caisson in this invention is that, before step 1, a load-bearing component is installed on the top of the caisson to increase its self-weight.

[0017] A further improvement of the construction method of using sheet piles to assist in caisson sinking is that, in step 3, the bottom elevation of the sheet pile is 1m to 1.5m lower than the bottom elevation of the cutting edge.

[0018] A further improvement of the construction method of using sheet piles to assist in sinking a caisson in this invention is that, in step 5, a water pump is installed inside the caisson to drain excess water from the caisson into the annular mud pool, so that the water depth inside the caisson is always within the range of 1m to 2m; in step 6, the water pump is used to pump out the water from the caisson.

[0019] The further improvement of the construction method of steel sheet pile assisted caisson sinking in this invention is that, in step 5, as the caisson sinks by itself, the soil inside the caisson is excavated, so that the elevation of the soil inside the caisson is kept no higher than the top elevation of the cutting edge.

[0020] Compared with the prior art, the advantages of the present invention are:

[0021] 1. By inserting and pulling the sheet piles around the caisson, the soil around the caisson is cut, reducing the lateral pressure of the strata on the caisson and facilitating the self-settlement of the caisson.

[0022] 2. By injecting water into the caisson, the soil at the bottom of the caisson's cutting edge is further softened, thereby further improving the caisson's self-sinking efficiency.

[0023] 2. By setting up the annular mud pit, when the sheet piles are inserted or extracted, the mud in the annular mud pit erodes the soil around the caisson, causing the soil around the caisson to be lost, which further reduces the lateral pressure of the soil on the caisson and improves the settlement effect. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the steel sheet pile insertion in the construction method of the present invention, which uses steel sheet piles to assist in the sinking of the caisson.

[0026] Figure 2 This is a schematic diagram showing the insertion of sheet piles into place in the construction method of the present invention, which uses sheet piles to assist in the sinking of caissons.

[0027] Figure 3 This is a schematic diagram of the sheet pile extraction process in the construction method of the present invention, which uses sheet piles to assist in the sinking of the caisson.

[0028] Figure 4 This is a top view of the construction status of the construction method of the present invention, which uses steel sheet piles to assist in the sinking of caissons.

[0029] In the diagram: 1. Caisson; 2. Circular mud pit; 3. Sheet pile; 4. Water pump; 5. Load-bearing component; 6. Compressed soil. Detailed Implementation

[0030] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0031] The following detailed description of the construction method of using steel sheet piles to assist in caisson sinking according to the present invention, with reference to the accompanying drawings and specific embodiments, will be further explained in detail.

[0032] Please see Figures 1-4 As shown, the construction method using sheet piles to assist in caisson sinking includes the following steps:

[0033] Step 1: After the caisson 1 is constructed, an annular mud pit 2 is excavated around the caisson 1, so that the annular mud pit 2 extends inward to the outer wall of the caisson 1, and mud is prepared in the annular mud pit 2.

[0034] Specifically, in step 1, bentonite is added to the annular mud pit 2 and water is injected to form the mud.

[0035] By adding bentonite and water to form mud, the soil loss around the outer perimeter of the caisson 1 was accelerated, and the lateral pressure around the outer perimeter of the caisson 1 was reduced.

[0036] Step 2: Inject water into the caisson 1 to soften the soil inside the caisson 1;

[0037] Step 3: Drive sheet piles 3 vertically downward from the annular mud pit 2, so that the bottom elevation of the sheet piles 3 is lower than the bottom elevation of the cutting edge of the caisson 1;

[0038] Specifically, when inserting the sheet pile 3, the sheet pile 3 should be placed as close as possible to the outer wall of the caisson 1.

[0039] Specifically, after the sheet pile 3 is driven into place, the soil cut by the sheet pile 3 will be forced to squeeze to both sides of the sheet pile 3. Some of the squeezed soil 6 will enter the cutting edge of the caisson 1 from the bottom of the caisson 1. A long-arm excavator is provided to dig out the squeezed soil 6 that has entered the caisson 1.

[0040] Step 4: After the sheet pile 3 is driven into place, pull it out and let the mud flow into the pile pit formed by pulling out the sheet pile 3.

[0041] Step 5: Repeat steps 3 to 4 above to allow the caisson 1 to sink to the designed position;

[0042] Step 6: After the caisson 1 is lowered to the designed position, the water inside the caisson 1 is pumped out and the annular mud pit 2 and the pile pit are backfilled.

[0043] Preferably, when performing step 3, with the axis of the caisson 1 as the axis of symmetry, two sheet piles 3 are driven vertically downwards symmetrically from the annular mud pit 2, so that the bottom elevation of the two sheet piles 3 is lower than the bottom elevation of the cutting edge of the caisson 1.

[0044] Preferably, during step 5, the driving points of the two sheet piles 3 are moved clockwise or counterclockwise along the annular mud pit 2.

[0045] By driving the sheet piles 3 symmetrically at multiple points, the self-sinking efficiency of the caisson 1 was increased, saving construction time.

[0046] Preferably, during step 5, the level instrument is used to monitor whether the settlement of the caisson 1 is uniform. When uneven settlement of the caisson 1 is detected, the insertion and extraction of the sheet pile 3 on the side with larger settlement is stopped, and the sheet pile 3 is inserted and extracted in a concentrated manner on the side with smaller settlement, so that the caisson 1 maintains uniform settlement.

[0047] Specifically, when the uneven settlement of the caisson 1 is detected to be no less than 40cm, the insertion and extraction of the sheet pile 3 on the side with the larger settlement should be stopped immediately, and the sheet pile 3 should be inserted and extracted in a concentrated manner on the side with the smaller settlement until the settlement of the caisson 1 is detected to be uniform.

[0048] Preferably, in step 3, a sheet pile 3 is driven vertically downward from the annular mud pit 2; in step 5, the driving point of the even-numbered sheet pile 3 is symmetrically arranged with respect to the driving point of the previous sheet pile 3 about the axis of the caisson 1.

[0049] Preferably, during step 5, a level instrument is used to monitor the unilateral settlement of the caisson 1 caused by each insertion and extraction of the sheet pile 3, and when the sheet pile 3 is inserted and extracted for an even number of times, the insertion depth and insertion speed are controlled based on the unilateral settlement of the previous time, so that the unilateral settlement of the two times is the same.

[0050] Specifically, when a sheet pile 3 is inserted and pulled on one side of the caisson 1, the caisson 1 will settle on one side. When the sheet pile 3 is inserted and pulled at two mutually symmetrical insertion points, the amount of settlement on one side is the same on both sides, so that the caisson 1 settles in a swinging manner.

[0051] Preferably, before proceeding to step 1, a load-bearing component 5 is installed on top of the caisson 1 to increase the weight of the caisson 1.

[0052] Specifically, the load-bearing component 5 is a cement bag, and there are multiple load-bearing components 5. Multiple cement bags are stacked at intervals on the top of the caisson 1, with a distance of 2m between two adjacent cement bags.

[0053] Specifically, before stacking multiple load components 5, the reserved steel bars at the top of the caisson 1 are bent. After the caisson 1 is lowered to the design position, multiple load components 5 are moved away and the reserved steel bars of the caisson 1 are straightened.

[0054] Preferably, during step 3, the bottom elevation of the sheet pile 3 is 1m to 1.5m lower than the bottom elevation of the cutting edge.

[0055] By limiting the driving depth of the sheet pile 3, the self-settlement of the caisson 1 is always kept within the control range, and even if uneven settlement occurs, it can be adjusted in time.

[0056] Preferably, when performing step 5, a water pump 4 is installed in the caisson 1 to pump excess water in the caisson 1 to the annular mud pool 2, so that the water depth in the caisson 1 is always within the range of 1m to 2m; when performing step 6, the water pump 4 is used to pump out the water in the caisson 1.

[0057] Water in the annular mud pool 2 will seep into the caisson 1 through the pile hole, causing an increase in water accumulation in the caisson 1. By returning the seepage water in the caisson 1 to the annular mud pool 2, water recycling is achieved, avoiding the continuous injection of water into the annular mud pool 2, which is in line with green construction.

[0058] Preferably, during step 5, as the caisson 1 sinks, the soil inside the caisson 1 is excavated, so that the elevation of the soil inside the caisson 1 is kept no higher than the top elevation of the cutting edge.

[0059] By limiting the soil elevation within the caisson 1 to no higher than the top elevation of the cutting edge, the soil within the settlement area is prevented from exerting lateral pressure on the inner wall of the caisson 1, thus affecting its self-settlement.

[0060] It should be noted that the structures, proportions, sizes, etc., illustrated in the accompanying drawings are merely for illustrative purposes to aid those skilled in the art and to facilitate understanding and reading. They are not intended to limit the scope of the invention and therefore have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effectiveness and purpose of the invention, should still fall within the scope of the technical content disclosed herein. Furthermore, the terms "upper," "lower," "left," "right," "middle," and "one" used in this specification are merely for clarity and not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.

[0061] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the technical solution of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A construction method for sinking a caisson with the aid of steel sheet piles, characterized in that, Including the following steps: Step 1: After the caisson construction is completed, an annular mud pit is excavated around the caisson, extending inward to the outer wall of the caisson, and mud is prepared in the annular mud pit. Step 2: Inject water into the caisson to soften the soil inside the caisson; Step 3: With the axis of the caisson as the axis of symmetry, drive two steel sheet piles vertically downwards symmetrically from the annular mud pit, so that the bottom elevation of the two steel sheet piles is lower than the bottom elevation of the cutting edge of the caisson. Step 4: After the sheet piles are driven into place, pull them out and let the mud flow into the pit formed by pulling out the sheet piles. Step 5: Repeat steps 3 to 4 above, moving the two sheet pile driving points clockwise or counterclockwise along the annular mud pit. Use a level to monitor whether the settlement of the caisson is uniform. When uneven settlement of the caisson is detected, stop inserting and pulling the sheet piles on the side with larger settlement, and concentrate on inserting and pulling the sheet piles on the side with smaller settlement to keep the caisson settling evenly and allow the caisson to sink to the design position. Step 6: After the caisson has sunk to the designed position, the water inside the caisson is pumped out and the annular mud pit and pile pit are backfilled.

2. The construction method of sinking a caisson with the aid of steel sheet piles according to claim 1, characterized in that, In step 3, a sheet pile is driven vertically downward from the annular mud pit; in step 5, the driving point of the even-numbered sheet pile is symmetrically arranged with respect to the driving point of the previous sheet pile along the axis of the caisson.

3. The construction method of sinking a caisson with the aid of steel sheet piles according to claim 2, characterized in that, During step 5, a level instrument is used to monitor the unilateral settlement of the caisson caused by each insertion and extraction of sheet piles. When the sheet piles are inserted and extracted for an even number of times, the insertion depth and speed are controlled based on the unilateral settlement of the previous time, so that the unilateral settlement of the two times are the same.

4. The construction method of sinking a caisson with the aid of steel sheet piles according to claim 1, characterized in that, Before proceeding to step 1, a load-bearing component is installed on top of the caisson to increase its self-weight.

5. The construction method for caisson sinking assisted by steel sheet piles as described in claim 1, characterized in that, In step 3, the bottom elevation of the sheet pile is made 1m to 1.5m lower than the bottom elevation of the cutting edge.

6. The construction method for caisson sinking assisted by steel sheet piles as described in claim 1, characterized in that, In step 5, a water pump is installed in the caisson to drain excess water from the caisson into the annular mud pit, so that the water depth in the caisson is always within the range of 1m to 2m; in step 6, the water pump is used to pump out the water from the caisson.

7. The construction method for caisson sinking assisted by steel sheet piles as described in claim 1, characterized in that, During step 5, as the caisson sinks, the soil inside the caisson is excavated, so that the elevation of the soil inside the caisson is kept no higher than the top elevation of the cutting edge.

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