CN114482155A - Construction method for pile soil isolation of empty pile section of ultra-long test pile - Google Patents

Abstract

The invention discloses a construction method for separating pile soil of an empty pile section of an overlong test pile. The construction method has high construction efficiency, good quality assurance and accurate and reliable data, overcomes the unfavorable conditions that the basement is excavated and needs to be supported and then tested, improves the accuracy of the result that the friction force is reduced by adopting an empirical parameter method to calculate deduction and adopting a high-pressure jet grouting vibroflotation method to disperse the soil, and avoids the defects of complex manufacture and installation and low quality assurance of the traditional double-casing device; the invention ensures that the friction force of the soil body of the empty pile section of the overlong test pile is effectively eliminated, and can obtain more accurate bearing capacity value data for the test of the overlong test pile.

Description

A construction method for pile-soil isolation of super-long test pile and empty pile section

technical field

The invention belongs to the technical field of building construction, and in particular relates to a construction method for the isolation of piles and soils of super-long test piles and empty pile sections.

Background technique

Pile foundations are widely used in super high-rise buildings. How to ensure the quality of bored cast-in-place piles in deep soft soil areas has become a difficult problem at this stage, while engineering pile test piles provide effective measures for the design and construction of subsequent engineering piles. parameter basis and experience reference. Many high-rise and even super-high-rise buildings have deep basements. Due to the construction conditions, it is impossible to excavate deeper soil. The test piles need to be constructed on the original ground, so there is a deep negative space (the depth from the ground to the design pile top). The actual construction of the piles The length of the pile is longer than the design effective pile length, and the pile length of the negative empty section is an invalid section. The friction force of the soil around the pile within the range of the pile length of this invalid section should not be considered in the bearing capacity value. The theoretical calculation and deduction of the test method, or the use of the high-pressure rotary jet vibrating method, cannot completely and accurately eliminate the soil friction on the side of the pile in the invalid section. In order to obtain more accurate bearing capacity value data, the double-casing isolation method is mostly used, but due to the lack of technological breakthroughs, similar projects currently use more complicated devices, which are inconvenient for construction. For this reason, it is very necessary to develop a construction method of pile-soil isolation in the super-long test pile and empty pile section.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a construction method of pile-soil isolation of super-long test piles and empty pile sections.

The object of the present invention is achieved in this way, comprising the following steps:

S1. Pile placement point: use a total station or RTK for placement, the error requirement is ≯ 1cm, and it is reviewed before drilling;

S2. Prepare the protective tube: the protective tube includes the outer protective tube 1 and the inner protective tube 2, both of which are round steel pipes. The length of the outer protective tube 1 is equal to the length of the negative space, and the length of the inner protective tube 2 is equal to the length of the outer protective tube 1 + 3.3 ~ 3.4m, a circle of limit plugging rings 3 is welded on the outer surface of the inner casing 2 near the upper and lower openings of the inner casing 2;

S3. Settling of the outer casing: transport the outer casing 1 to the vicinity of the piles to be formed, lift the outer casing 1 by the lifting equipment, and clamp the top of the outer casing 1 with the clamp 5 of the ICE hydraulic vibratory hammer 4. The outer casing 1 is lifted off the ground and transported to the top of the pile for centering and vertical adjustment. The ICE hydraulic vibratory hammer 4 is started, and the outer casing 1 is vibrated and sunk to the required elevation slowly. The verticality is monitored in real time during the sinking process, and the outer casing is completed. 1 sink;

S4. Settling of the inner casing: Drill the hole to the design pile top elevation through a rotary excavator, so that the soil in the outer casing 1 is taken out, and the lifting equipment, ICE hydraulic vibrating hammer 4 and fixture 5 are used to follow the steps of S3. In the same process of sinking the outer casing, the inner casing 2 is vibrated. The sinking process ensures that the inner casing 2 is located in the center of the outer casing 1 and the verticality is monitored in real time. The limit sealing ring 3 corresponding to the upper port of 2 is 0.4-0.6m away from the upper port of the outer casing 1, and the limit sealing ring 3 corresponding to the lower port of the inner casing 2 is 0.4-0.6m away from the lower port of the outer casing 1;

S5. The inner and outer protective cylinders are closed: the gap area between the inner and outer protective cylinders between the limit blocking ring 3 corresponding to the upper opening of the inner protective cylinder 2 and the upper opening of the outer protective cylinder 1 is blocked and closed with a woven bag and clay. on the woven bag.

Compared with the prior art, the present invention has the following technical effects:

1. The construction method of the present invention has high construction efficiency, good quality assurance, and accurate and reliable data, overcomes the disadvantageous conditions of excavating a basement with a relatively large volume of soil and needs to support and then conducts tests, and improves the calculation and deduction of the empirical parameter method in the past. , the high-pressure rotary jet vibrating method to disperse the soil to reduce the accuracy of the result of the friction force, and avoid the disadvantages of the existing double-casing device that is complicated to manufacture and install, and the quality assurance is not high; the invention ensures that the super-long test pile is empty. The soil friction force of the pile section (from the ground to the depth of the design pile top) is effectively eliminated, and more accurate bearing capacity value data can be obtained for the test of the super-long test pile;

2. The inner casing of the present invention is longer than the outer casing, and the bottom end of the inner casing extends out of the outer casing for a certain distance. When the ICE hydraulic vibrating hammer vibrates and sinks the casing, the disturbance to the deep soil body is small, and the soil body at the bottom end itself can form a self-contained structure. closed space;

3. The limit plugging ring is used to reduce the horizontal displacement tolerance of the upper part of the inner casing, adapt to the local size error and micro-deformation of the casing, and at the same time play an auxiliary plugging role, of which the bottom limit plugging ring In addition to the limit, it can be used as a safety device to enhance the sealing tightness of the bottom opening of the inner and outer casings, and the top limit sealing ring, together with woven bags and clay filling, can prevent the top mud and concrete from falling into the inner and outer casings. After sealing, a "gas plug" will be formed between the inner and outer casings to enhance the sealing effect, and it does not need to be removed during loading.

Description of drawings

Fig. 1 is the schematic flow chart of the present invention;

Fig. 2 is a schematic diagram of the sinking structure of the casing;

Figure 3 is a schematic diagram of the vertical structure of the inner and outer casings;

Figure 4 is a schematic diagram of the extension of the protective tube;

Figure 5 is a schematic view of the top of the protective tube full wrapping;

In the picture: 1-Outer casing, 2-Inner casing, 3-Limited sealing ring, 4-ICE hydraulic vibrating hammer, 5-Clamp, 6-Total station, 7-Pile position, 8-Clay sealing, 9- Woven bag closure.

Detailed ways

The present invention is further described below in conjunction with the accompanying drawings, but the present invention is not limited in any way, and any transformation or replacement based on the teachings of the present invention belongs to the protection scope of the present invention.

The present invention includes the following steps as shown in accompanying drawings 1 to 5:

S1. Pile placement point: use a total station or RTK for placement, the error requirement is ≯ 1cm, and it is reviewed before drilling;

S2. Prepare the protective tube: the protective tube includes the outer protective tube 1 and the inner protective tube 2, both of which are round steel pipes. The length of the outer protective tube 1 is equal to the length of the negative space, and the length of the inner protective tube 2 is equal to the length of the outer protective tube 1 + 3.3 ~ 3.4m, a circle of limit plugging rings 3 is welded on the outer surface of the inner casing 2 near the upper and lower openings of the inner casing 2;

S3. Settling of the outer casing: transport the outer casing 1 to the vicinity of the piles to be formed, lift the outer casing 1 by the lifting equipment, and clamp the top of the outer casing 1 with the clamp 5 of the ICE hydraulic vibratory hammer 4. The outer casing 1 is lifted off the ground and transported to the top of the pile for centering and vertical adjustment. The ICE hydraulic vibratory hammer 4 is started, and the outer casing 1 is vibrated and sunk to the required elevation slowly. The verticality is monitored in real time during the sinking process, and the outer casing is completed. 1 sink;

S4. Settling of the inner casing: Drill the hole to the design pile top elevation through a rotary excavator, so that the soil in the outer casing 1 is taken out, and the lifting equipment, ICE hydraulic vibrating hammer 4 and fixture 5 are used to follow the steps of S3. In the same process of sinking the outer casing, the inner casing 2 is vibrated. The sinking process ensures that the inner casing 2 is located in the center of the outer casing 1 and the verticality is monitored in real time. The limit sealing ring 3 corresponding to the upper port of 2 is 0.4-0.6m away from the upper port of the outer casing 1, and the limit sealing ring 3 corresponding to the lower port of the inner casing 2 is 0.4-0.6m away from the lower port of the outer casing 1;

S5. The inner and outer protective cylinders are closed: the gap area between the inner and outer protective cylinders between the limit blocking ring 3 corresponding to the upper opening of the inner protective cylinder 2 and the upper opening of the outer protective cylinder 1 is blocked and closed with a woven bag and clay. on the woven bag.

In step S2, the wall thickness of the round steel pipe is 11-13mm, preferably 12mm, the steel grade is Q345B, the inner diameter of the outer casing 1 is the pile diameter+19-21cm, and the selected pile diameter+20cm, the inner diameter of the inner casing 2 is the pile diameter+9～ 11cm, preferably pile diameter+10cm.

Step S2 The outer shield 1 and the inner shield 2 are made of multiple sections of shields welded in sequence, which are suitable for the case where the shield is long (usually more than 12m in length) and cannot be transported as a whole. Therefore, for on-site welding, E50 type electrode arc is used for welding. For welding or CO ₂ gas shielded welding, the welding joints of the protective tube should be welded with a "V"-shaped groove, and the four directions should be spot welded and fixed before full welding. Using positioning auxiliary plate or steel bar, the welding seam is continuous and full, which can meet the stress and construction requirements.

After the welding of the protective tube joint is completed, 300*150mm steel plate (reinforced plate) with the same thickness and radian is used on the four sides of the joint to strengthen the connection and enhance the stability.

Step S2 Step S2 The upper openings of the outer casing 1 and the inner casing 2 are welded with 25cm wide casing steel plates, and the edging is helpful for the clamp 5 to clamp the casing, ensuring the ICE is stable and strengthening; Weld a hoisting ring or opening at the place, which is convenient for fixing the protective tube through the buckle and lifting it.

In step S2, the limit blocking ring 3 is made of round steel.

In step S4, the distance between the limit sealing ring 3 corresponding to the upper opening of the inner protective tube 2 and the upper opening of the outer protective tube 1 is preferably 0.5m, and the distance between the limit sealing ring 3 corresponding to the lower opening of the inner protective tube 2 and the lower opening of the outer protective tube 1 is preferably 0.5 m. is 0.5m.

The present invention will be further described below in conjunction with Embodiment 1 to Embodiment 10.

Example 1

The construction method of the pile-soil isolation of the super-long test pile and the empty pile section of the present embodiment includes the following steps:

S1. Pile position release point: use a total station to release, the error requirement is ≯ 1cm, and check before drilling;

S2. Prepare the protective tube: the protective tube includes the outer protective tube 1 and the inner protective tube 2, both of which are round steel pipes. The length of the outer protective tube 1 is equal to the length of the negative space, and the length of the inner protective tube 2 is equal to the length of the outer protective tube 1 + 3.3m, on the outer surface of the inner casing 2 near the upper and lower openings of the inner casing 2, a circle of limit blocking rings 3 are welded respectively;

S3. Settling of the outer casing: transport the outer casing 1 to the vicinity of the piles to be formed, lift the outer casing 1 by the lifting equipment, and clamp the top of the outer casing 1 with the clamp 5 of the ICE hydraulic vibratory hammer 4. The outer casing 1 is lifted off the ground and transported to the top of the pile for centering and vertical adjustment. The ICE hydraulic vibratory hammer 4 is started, and the outer casing 1 is vibrated and sunk to the required elevation slowly. The verticality is monitored in real time during the sinking process, and the outer casing is completed. 1 sink;

S4. Settling of the inner casing: Drill the hole to the design pile top elevation through a rotary excavator, so that the soil in the outer casing 1 is taken out, and the lifting equipment, ICE hydraulic vibrating hammer 4 and fixture 5 are used to follow the steps of S3. In the same process of sinking the outer casing, the inner casing 2 is vibrated. The sinking process ensures that the inner casing 2 is located in the center of the outer casing 1 and the verticality is monitored in real time. 2. The limit blocking ring 3 corresponding to the upper port is 0.4m away from the upper port of the outer casing 1, and the limit blocking ring 3 corresponding to the lower port of the inner casing 2 is 0.4m away from the lower port of the outer casing 1;

S5. The inner and outer protective cylinders are closed: the gap area between the inner and outer protective cylinders between the limit blocking ring 3 corresponding to the upper opening of the inner protective cylinder 2 and the upper opening of the outer protective cylinder 1 is blocked and closed with a woven bag and clay. on the woven bag.

Example 2

The construction method of the pile-soil isolation of the super-long test pile and the empty pile section in this embodiment, except that RTK is used in step S1, the length of the inner casing 2 in step S2 is equal to the length of the outer casing 1 + 3.4m, and the upper opening of the inner casing 2 in step S4 The corresponding limit blocking ring 3 is 0.6m away from the upper port of the outer casing 1, and the limit blocking ring 3 corresponding to the lower port of the inner casing 2 is 0.6m away from the lower port of the outer casing 1, and the rest are the same as in Example 1.

Example 3

The construction method of the pile-soil isolation of the super-long test pile and the empty pile section in this embodiment, except that the length of the inner casing 2 in step S2 is equal to the length of the outer casing 1 + 3.35m, and the limit seal corresponding to the upper opening of the inner casing 2 in step S4 The blocking ring 3 is 0.5m away from the upper mouth of the outer casing 1, and the limit blocking ring 3 corresponding to the lower mouth of the inner casing 2 is 0.5m away from the lower mouth of the outer casing 1, and the rest are the same as in Example 1.

Example 4

The construction method of the pile-soil isolation of the super-long test pile and the empty pile section of the present embodiment is based on the embodiment 1, the wall thickness of the round steel pipe in step S2 is 11mm, the inner diameter of the outer casing 1 is the pile diameter+19cm, and the inner diameter of the inner casing 2 is the pile diameter+19cm. For the pile diameter +9cm.

Example 5

The construction method of the pile-soil isolation of the super-long test pile and the empty pile section of the present embodiment is based on Example 2, the wall thickness of the round steel pipe in step S2 is 13mm, the inner diameter of the outer casing 1 is the pile diameter+21cm, and the inner diameter of the inner casing 2 is the pile diameter+21cm. For the pile diameter +11cm.

Example 6

The construction method of the pile-soil isolation of the super-long test pile and the empty pile section of the present embodiment is based on Example 3, the wall thickness of the round steel pipe in step S2 is 12mm, the inner diameter of the outer casing 1 is the pile diameter+20cm, and the inner diameter of the inner casing 2 is the pile diameter+20cm. For the pile diameter +10cm.

Example 7

The construction method of the pile-soil isolation of the super-long test pile and the empty pile section in the present embodiment is based on the embodiment 4. In step S2, the outer casing 1 and the inner casing 2 are both formed by welding multiple sections of casings in sequence. For E50 type electrode arc welding, the welding joints of the protective tube should be welded with a "V"-shaped groove, and the four directions should be spot welded and fixed before full welding. Auxiliary panel or reinforcement.

Example 8

In the construction method of the pile-soil isolation of the super-long test pile and the empty pile section in this embodiment, except for the step S2, the multi-section shield welding adopts CO ₂ gas shielded welding. The rest is the same as in Example 7, except that the steel plate is back welded to strengthen the connection.

Example 9

The construction method of the pile-soil isolation of the super-long test pile and the empty pile section in this embodiment is based on the embodiment 8. In step S2, the upper openings of the outer casing 1 and the inner casing 2 are welded with wide casing steel plates.

Example 10

The construction method of the pile-soil isolation of the super-long test pile and the empty pile section in this embodiment is based on the embodiment 9, and the limit plugging ring 3 in step S2 is a round steel with a diameter of 22 mm.

Claims (6)

1. a construction method of super-long test pile empty pile section pile-soil isolation is characterized in that comprising the following steps: S1. Pile placement point: use a total station or RTK for placement, the error requirement is ≯ 1cm, and it is reviewed before drilling; S2. Prepare the protective tube: the protective tube includes an outer protective tube (1) and an inner protective tube (2), both of which are round steel pipes. The length of the outer protective tube (1) is equal to the length of the negative space, and the length of the inner protective tube (2) Equal to the length of the outer casing (1) + 3.3 to 3.4 m, and a limit sealing ring (3) is welded on the outer surface of the inner casing (2) near the upper and lower openings of the inner casing (2); S3. Settling of the outer casing: transport the outer casing (1) to the vicinity of the pile to be formed, lift the outer casing (1) by the lifting equipment, and clamp it with the clamp (5) of the ICE hydraulic vibrating hammer (4). Hold the top of the outer casing (1), lift the outer casing (1) off the ground and transport it to the top of the pile for centering and vertical adjustment, start the ICE hydraulic vibrating hammer (4), and slowly vibrate and sink the outer casing (1). To the required elevation, the verticality is monitored in real time during the sinking process, and the sinking of the outer casing (1) is completed; S4. Settling of the inner casing: Drill the hole through the rotary excavator to the designed pile top elevation, so that the soil in the outer casing (1) is taken out, and the soil in the outer casing (1) is taken out. 5), according to the same process of sinking the outer casing in step S3, vibrate and sink the inner casing (2), the sinking process ensures that the inner casing (2) is located in the center of the outer casing (1) (2) The bottom end protrudes from the outer casing (1) 3m, the limit sealing ring (3) corresponding to the upper port of the inner casing (2) is 0.4-0.6m away from the upper mouth of the outer casing (1), and the inner casing ( 2) The limit sealing ring (3) corresponding to the lower port is 0.4-0.6m away from the lower port of the outer casing (1); S5. Closure of the inner and outer casings: Use woven bags and woven bags in the gap area between the inner and outer casings between the upper opening of the inner casing (2) and the upper opening of the outer casing (1). The clay is plugged and closed, and the clay is placed on top of the woven bag. 2. according to the construction method of the super-long test pile empty pile section pile-soil isolation of claim 1, it is characterized in that the wall thickness of the round steel pipe in step S2 is 11～13mm, and the inner diameter of the outer casing (1) is the pile diameter+19～21cm, The inner diameter of the inner casing (2) is the pile diameter+9-11cm. 3. according to the construction method of the super-long test pile empty pile section pile-soil isolation of claim 1, it is characterized in that in step S2, the outer casing (1) and the inner casing (2) are all formed by welding multiple sections of casings in turn. , Use E50 type electrode arc welding or CO ₂ gas shielded welding for welding. The welding joint of the protective tube should be welded with a "V" shape groove. First, the four positions are fixed by spot welding and then fully welded. The welding protective tube is straight and straight. And ensure that the axis is concentric, and the four corners use positioning auxiliary panels or steel bars. 4. according to the construction method of the super-long test pile empty pile section pile-soil isolation of claim 3, it is characterized in that after the welding of the casing joint is completed, the back welding of steel plates with the same thickness and radian is used to strengthen the connection on the four sides of the joint respectively. . 5. according to the construction method of the super-long test pile empty pile section pile-soil isolation of claim 1, it is characterized in that in step S2 the outer casing (1), the upper opening of the inner casing (2) all adopt wide casing steel plates for welding edging. 6. The construction method of the super-long test-pile-empty-pile section pile-soil isolation according to claim 1, characterized in that the limit plugging ring (3) in step S2 is a round steel.

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