Construction method of dry drilling to prevent collapse of pile foundation

Abstract

The present invention discloses a construction method for pile foundation dry drilling to prevent collapse, comprising the following construction steps: S1: understanding the soil conditions at different depths through geological survey reports and test piles; S2: staking out the pile position before drilling; S3: drilling to the lowest undesirable soil layer at the pile core; S4: improving the undesirable soil layer within a range not less than the pile diameter using high-pressure rotary grouting; S5: placing a steel cage and pouring concrete. This method can solve the hole-drilling process that cannot be implemented using long spiral dry drilling processes, and can also address the risk of collapse in deep hole drilling using rotary drilling dry drilling. Compared with the mud wall protection process, the on-site civilized construction is cleaner and can effectively improve the soil quality and increase the friction force of pile drilling.

Description

Technical Field

[0001] The invention relates to the technical field of construction engineering, in particular to a construction method for pile foundation dry-operation hole forming to prevent collapse. Background Art

[0002] In construction projects, the foundations of high-rise buildings are mostly pile foundations, especially in northern projects where the piles are designed to be long and the groundwater level is low. The pile foundation drilling process is mostly dry drilling (long spiral drilling, rotary drilling, manual bored piles, etc.). During the drilling construction process, when encountering poor soil quality, especially when the geology is backfill soil, sandy soil, sandy soil and small-grained gravel layer, it is easy to collapse. At the same time, deep hole dry drilling also brings a greater risk of collapse. Summary of the Invention

[0003] In view of this, the present invention provides a construction method for preventing collapse of pile foundation during dry drilling, which solves the collapse problem during drilling operations in poor soil layers as mentioned above.

[0004] The present invention provides a construction method for pile foundation dry drilling to prevent collapse, which adopts the following technical solutions:

[0005] A construction method for pile foundation dry drilling to prevent collapse, comprising the following construction steps:

[0006] S1: Understand the soil conditions at different depths through geological survey reports and pile tests;

[0007] S2: stake out the pile position before drilling;

[0008] S3: Drilling to the lowest unfavorable soil layer at the pile core location;

[0009] S4: Use high-pressure rotary grouting to improve the poor soil layer within the range of not less than the pile diameter;

[0010] S5: Place the steel cage and pour concrete.

[0011] Optionally, in S3, a casing is placed in the borehole after the drilling is completed, and the casing can be broken during the high-pressure jet grouting process.

[0012] Optionally, the casing includes a first sleeve and a second sleeve, the first sleeve and the second sleeve are made of different materials, the first sleeve and the second sleeve are detachably connected, the length of the second sleeve is approximately the height of the poor soil layer, and when placing the casing, the second sleeve is placed in the poor soil layer.

[0013] Optionally, a sound collector is provided on the grouting pipe used in the high-pressure rotary jet grouting method of S4. The sound collector is used to collect sound information during the grouting process and can identify different sounds of the grouting liquid being sprayed into the first sleeve and the second sleeve.

[0014] Optionally, the first sleeve is a PVC sleeve and the second sleeve is a low-carbon steel sleeve.

[0015] Optionally, a guide rod is installed on the side wall of the grouting pipe, and the guide rod can contact the inner wall of the casing.

[0016] Optionally, a guide wheel is provided at one end of the guide rod away from the bottom wall of the borehole, and the guide wheel contacts the inner wall roller of the casing.

[0017] Optionally, a sound collector is used to collect different sounds caused by the guide wheel contacting the PVC sleeve and the low carbon steel sleeve.

[0018] Optionally, in S3, an inclinometer is used to measure the verticality of the borehole during the drilling process.

[0019] In summary, the present invention includes at least one of the following beneficial technical effects: it can solve the hole-making process that cannot be implemented by the long spiral dry operation process, it can solve the risk of collapse in deep hole making by rotary drilling dry operation, and compared with the mud wall protection process, the on-site civilized construction is cleaner, it can effectively improve the soil quality and increase the friction force of pile formation. DETAILED DESCRIPTION

[0020] The embodiment of the present invention discloses a construction method for pile foundation dry drilling to prevent collapse.

[0021] A construction method for pile foundation dry drilling to prevent collapse, comprising the following construction steps:

[0022] S1: Understand the soil conditions at different depths through geological survey reports and pile tests;

[0023] S2: stake out the pile position before drilling;

[0024] S3: Drilling to the lowest unfavorable soil layer at the pile core location;

[0025] S4: Use high-pressure rotary grouting to improve the poor soil layer within the range of not less than the pile diameter;

[0026] S5: Place the steel cage and pour concrete.

[0027] In S3, casing is placed into the borehole after drilling is complete. The casing is broken during the high-pressure jet grouting process. The casing prevents the borehole wall from collapsing, effectively avoiding the risk of collapse when drilling into poor soil quality.

[0028] In this embodiment, the sleeve includes a first sleeve and a second sleeve. The first sleeve and the second sleeve are made of different materials. In this embodiment, the first sleeve is made of PVC and the second sleeve is made of low-carbon steel.

[0029] The first sleeve and the second sleeve are detachably connected. In this embodiment, the first sleeve and the second sleeve are detachably connected by bolts. The staff makes the length of the second sleeve approximate to the height of the poor soil layer according to the geological survey report and the location of the poor soil of the test pile, and then installs the second sleeve on the first sleeve. When the casing is placed in the borehole, the second sleeve can be placed in the poor soil layer.

[0030] The grouting tube used in the S4 high-pressure rotary jet grouting method is equipped with a sound collector. This device collects sound information during the grouting process and can identify the different sounds of the grouting liquid being sprayed into the first and second sleeves. The sound collector identifies the different waveforms of the grouting liquid spraying from the grouting tube into the first and second sleeves based on the sound wave pattern, thus determining the position of the grouting tube.

[0031] Guide rods are installed on the side walls of the grouting pipe, which can contact the inner wall of the casing. The guide rods guide the grouting pipe, effectively preventing lateral displacement during the spraying process and ensuring the spraying effect.

[0032] A guide wheel is provided at one end of the guide rod away from the bottom wall of the borehole, and the guide wheel contacts the inner wall roller of the casing. The guide wheel adopts a steel wheel.

[0033] To further improve identification accuracy, a sound collector is used to collect the different sounds of the guide wheel contacting the PVC sleeve and the mild steel sleeve. The sound of the steel wheel contacting the PVC sleeve is different from that of the mild steel sleeve, thus identifying the location of the grouting pipe.

[0034] The guide wheel is located behind the injection port of the grouting pipe. The staff can judge the general position of the grouting pipe through the sound collector. When it is located at the second sleeve, the grouting is carried out. When it is located at the first sleeve, the grouting is stopped, thereby improving the accuracy of grouting.

[0035] The impact force of high-pressure liquid flow is used to destroy the soil layer and casing, and a new soil layer is formed with the soil. Since the second sleeve after the impact contains low-carbon steel, after the second sleeve is broken by the high-pressure liquid flow, the fragments of the second sleeve are re-mixed with the concrete, which makes the poor soil layer additionally reinforced. Compared with pure concrete, the strength here is further improved, which enhances the improvement effect of the poor soil layer and further improves safety.

[0036] In S3, an inclinometer was used to measure the verticality of the borehole during the drilling process.

[0037] The soil conditions at different depths are understood through geological survey reports and test piles. The pile positions are then staked out before drilling. Holes are drilled at the pile core to the lowest undesirable soil layer. High-pressure rotary grouting is used to improve the undesirable soil layer within a range not less than the pile diameter, and dry drilling is then performed.

[0038] After knowing the depth of poor soil and the thickness of the soil layer, the soil layer is improved using high-pressure jet grouting. The process flow is: pile position layout → drilling rig placement → pile core drilling (the hole diameter matches the grouting pipe diameter, and the hole depth is considered according to the depth and thickness of the poor soil layer) → grouting pipe placement → high-pressure rotary grouting and pulling out the grouting pipe, so that the soil in the poor soil layer is improved to form a "plain soil pile".

[0039] After the poor soil layer reaches a certain strength, normal dry operations such as pile position layout and drilling rig positioning will be carried out.

[0040] This construction method can solve the hole-forming process (such as large-diameter, deep-hole pile formation) that cannot be implemented with long spiral dry operation processes. It can also eliminate the risk of collapse in deep-hole drilling operations using rotary drilling dry operations. Compared with mud wall protection processes, the construction site is more civilized and cleaner. The construction site is dry and not muddy, making construction easier. It can effectively improve the soil quality and increase the friction force for pile formation. It solves the problem of collapse during drilling operations in poor soil layers, the problem of collapse during deep-hole dry drilling, and the problem of collapse in large-diameter dry drilling operations. It effectively shortens the construction period of deep-hole, large-diameter pile foundations and reduces the construction cost of deep-hole, large-diameter pile foundations.

[0041] The above are all preferred embodiments of the present invention, and are not intended to limit the scope of protection of the present invention. Therefore, any equivalent changes made based on the structure, shape, and principle of the present invention should be included in the scope of protection of the present invention.

Claims

1. A construction method for pile foundation dry drilling to prevent collapse, characterized by: The construction steps include: S1: Understand the soil conditions at different depths through geological survey reports and pile tests; S2: stake out the pile position before drilling; S3: Drilling to the lowest unfavorable soil layer at the pile core location; S4: Use high-pressure rotary grouting to improve the poor soil layer within the range of not less than the pile diameter; S5: Place the steel cage and pour concrete; In S3, after the drilling is completed, a casing is placed in the borehole. The casing can be broken during the high-pressure rotary grouting process. The casing includes a first sleeve and a second sleeve. The first sleeve and the second sleeve are made of different materials. The first sleeve and the second sleeve are detachably connected. The length of the second sleeve is approximately the same as the height of the undesirable soil layer. When placing the casing, the second sleeve is placed in the undesirable soil layer. The grouting pipe used in the S4 medium- and high-pressure rotary jet grouting method is equipped with a sound collector, which is used to collect sound information during the grouting process and can identify the different sounds of the grouting liquid being sprayed into the first sleeve and the second sleeve.

2. The construction method for pile foundation dry drilling to prevent collapse according to claim 1, characterized in that: The first sleeve is made of PVC sleeve and the second sleeve is made of mild steel sleeve.

3. The construction method for pile foundation dry drilling to prevent collapse according to claim 1, characterized in that: A guide rod is installed on the side wall of the grouting pipe, and the guide rod can contact the inner wall of the casing.

4. The construction method for pile foundation dry drilling to prevent collapse according to claim 3, characterized in that: A guide wheel is provided at one end of the guide rod away from the bottom wall of the borehole, and the guide wheel contacts the inner wall roller of the casing.

5. The construction method for pile foundation dry drilling to prevent collapse according to claim 4, characterized in that: The sound collector is used to collect different sounds when the guide wheel contacts the PVC sleeve and the low carbon steel sleeve.

6. The construction method for pile foundation dry drilling to prevent collapse according to claim 1, characterized in that: In S3, an inclinometer is used to measure the verticality of the borehole during the drilling process.