CN113445496A - Rotary drilling cast-in-place pile and construction process thereof - Google Patents

Abstract

The application relates to the field of pile foundation construction, in particular to a rotary drilling bored pile and a construction process thereof. The rotary drilling bored concrete pile is prepared from concrete mixture; the concrete mixing material comprises 853-965 parts of coarse aggregate, 486-558 parts of fine sand, 186-198 parts of cement, 25-38 parts of bentonite, 169-178 parts of water, 4.0-8.5 parts of a water reducing agent, 1.9-3.0 parts of polyaluminum silicate sulfate, 2.1-3.5 parts of sodium polyacrylate and 5.3-6.7 parts of sodium silicate in parts by weight; the preparation method comprises the following steps: leveling a field, positioning a pile foundation, embedding a pile casing, cleaning holes, installing a reinforcement cage, installing a concrete conduit and pouring concrete mixture. This application has the condition that reduces "disconnected stake" and takes place the advantage.

Description

Rotary drilling cast-in-place pile and construction process thereof

Technical Field

The application relates to the field of pile foundation construction, in particular to a rotary drilling bored pile and a construction process thereof.

Background

The pile foundation is a common foundation form in the field of construction, and the cast-in-place pile is formed by pouring concrete into a pre-drilled hole and forming a pile body after the concrete is solidified to form a foundation pile. Drilling is a key process for forming a cast-in-place pile and a pile foundation, and the conventional drilling is generally completed by using a rotary drilling machine and adopting a forward (reverse) circulation process or using a percussion drill and an impact process.

Because the depth of the cast-in-place pile is generally deeper, more concrete is needed, when concrete is cast into the drill hole, the initial setting of the concrete which is cast first is easy to happen, if the bottom concrete is solidified, but the upper concrete is not cast, the pile breaking happens, the bearing capacity of the cast-in-place pile is greatly reduced, and therefore improvement is needed.

Disclosure of Invention

In order to reduce the occurrence of the 'broken pile', the rotary drilling cast-in-place pile and the construction process thereof are provided.

In a first aspect, the present application provides a rotary drilling bored concrete pile, which adopts the following technical scheme:

a rotary drilling bored concrete pile is prepared from concrete mixture; the concrete mixture comprises 853-965 parts of coarse aggregate, 486-558 parts of fine sand, 186-198 parts of cement, 25-38 parts of bentonite, 169-178 parts of water, 4.0-8.5 parts of a water reducing agent, 1.9-3.0 parts of polyaluminum silicate sulfate, 2.1-3.5 parts of sodium polyacrylate and 5.3-6.7 parts of sodium silicate in parts by weight.

By adopting the technical scheme, under the common cooperation of the polyaluminium silicate sulfate, the sodium polyacrylate and the sodium silicate, the setting time of the cement is prolonged, the retarding effect is achieved, the lower layer concrete is not solidified too fast in the pouring process, and the occurrence of pile breakage is reduced; meanwhile, the connection strength among all the substances is enhanced, so that the cast-in-place pile has good anti-permeability performance, and when a small amount of underground water invades into the drilled hole, the underground water is not easy to invade into the cast-in-place pile.

The inventor guesses that the sodium silicate has certain modification on the polyaluminium silicate sulfate and the sodium polyacrylate, and the electrical neutralization and adsorption bridging effects of the polyaluminium silicate sulfate and the sodium polyacrylate are enhanced. Under the common cooperation of sodium silicate, poly aluminum silicate sulfate and sodium polyacrylate, the intermolecular acting force between a polysilicic acid molecular chain and the surface of colloidal particles is improved, the setting time of cement is prolonged, the condensation effect among all the substances is improved, the reaction among all the substances is more sufficient, the connection strength among all the substances is enhanced, and water is not easy to permeate into concrete. Meanwhile, under the cooperation of the three components, the effect of sodium polyacrylate for water retention is improved, the sodium polyacrylate is dispersed in the concrete to play a role in lubrication, the friction among various raw materials is reduced, the fluidity of the concrete is improved, and the concrete is uniformly mixed in all positions in the process of pouring the concrete, so that the pile breaking is not easy to happen.

Preferably, the concrete mixture also comprises 1.2 to 1.9 weight parts of sodium alginate.

By adopting the technical scheme, under the common cooperation of sodium alginate, sodium polyacrylate and aluminum polysilicate sulfate, sodium alginate modifies sodium polyacrylate and aluminum polysilicate sulfate to some extent, the influence of sodium polyacrylate and aluminum polysilicate sulfate on the compressive strength of concrete is well relieved, and the compressive strength of concrete is effectively improved.

Preferably, the concrete mixture also comprises 5.8-7.6 parts of dura fiber.

Through adopting above-mentioned technical scheme, under the common cooperation of dola fibre and poly aluminium silicate sulfate, sodium polyacrylate and sodium silicate, formed certain network structure, improved joint strength between various raw materials for the reaction is more abundant between each raw materials, has also given various raw materials reaction time more abundant, thereby has further improved the impervious effect and the mobility of concrete.

Preferably, the water reducing agent is one or more of a sulfamate water reducing agent, a naphthalene water reducing agent and a polycarboxylic acid water reducing agent.

Preferably, the water reducing agent is a sulfamate water reducing agent and a naphthalene water reducing agent, and the weight ratio of the sulfamate water reducing agent to the naphthalene water reducing agent is 1 (1.2-1.4)

By adopting the technical scheme, the cement particles can be further dispersed by adopting the water reducing agent of a specific kind, particularly the water reducing agent matched in a specific proportion, so that various raw materials can be contacted and reacted more closely, and the fluidity and the anti-permeability effect of the concrete are improved.

Preferably, the coarse aggregate comprises common crushed stones and recycled crushed stones, and the weight ratio of the common crushed stones to the recycled crushed stones is 1: (0.8-1.2).

By adopting the technical scheme, the recycled macadam is low in price, the performance of the common macadam is good, and the mixed coarse aggregate has better mechanical property and economical efficiency under the matching of a specific proportion.

Preferably, the preparation method of the concrete mixture comprises the following steps:

step 1): uniformly mixing cement and bentonite to obtain a primary mixed material;

step 2): uniformly mixing the primary mixed material with other raw materials except the coarse aggregate to obtain a middle mixed material;

step 3): and uniformly mixing the medium mixture and the coarse aggregate to obtain a finished product.

By adopting the technical scheme, the primary mixed material is premixed, various raw materials except the aggregate are uniformly mixed with the primary mixed material, so that the various raw materials can be more fully reacted, and then the coarse aggregate is added, so that the intermediate mixed material is more fully wrapped outside the coarse aggregate, and the performances of all aspects of concrete, especially the anti-permeability effect and the fluidity are improved.

In a second aspect, the present application provides a construction process for a rotary drilling cast-in-place pile, which adopts the following technical scheme: a construction process of a rotary drilling bored concrete pile comprises the following steps:

step a): leveling a field, then measuring and paying off, and measuring the ground elevation in the field;

step b): positioning a pile foundation, drilling and digging the pile foundation to a set hole depth at an appointed position by a rotary drilling rig, and embedding a pile casing;

step c): the supporting layer can be used for cleaning the hole in detail, and after the supporting layer is used for surveying in detail, the drill bucket is processed to discharge sediments;

step d): vertically installing a reinforcement cage into the drilled hole;

step e): installing a concrete guide pipe in the drill hole;

step f): and continuously pouring concrete mixture into the reinforcement cage through the concrete guide pipe, and standing and maintaining to obtain the cast-in-place pile.

Through adopting above-mentioned technical scheme, in concrete mixture entered into the steel reinforcement cage through the concrete pipe, concrete mixture lastingly and accurately carried the drilling in, reduced the condition emergence of bored concrete pile "disconnected stake".

In summary, the present application has the following beneficial effects:

1. under the common cooperation of the polyaluminium silicate sulfate, the sodium polyacrylate and the sodium silicate, the setting time of the concrete is prolonged, so that the occurrence of pile breakage is reduced; meanwhile, the connection strength among all the substances is enhanced, so that the cast-in-place pile has good anti-permeability performance, and when a small amount of underground water invades into the drilled hole, the underground water is not easy to invade into the cast-in-place pile.

2. Under the common cooperation of sodium alginate, sodium polyacrylate and aluminum polysilicate sulfate, sodium alginate modifies sodium polyacrylate and aluminum polysilicate sulfate, the influence of sodium polyacrylate and aluminum polysilicate sulfate on the compressive strength of concrete is well relieved, and the compressive strength of concrete is effectively improved.

3. Under the common cooperation of the dura fiber, the polymeric aluminum silicate sulfate, the sodium polyacrylate and the sodium silicate, a certain mesh structure is formed, the connection strength among various raw materials is improved, the reaction among the raw materials is more sufficient, and the anti-permeability effect and the fluidity of the concrete are further improved.

Detailed Description

The present application will be described in further detail with reference to examples.

The information on the source of the raw materials used in the following examples and comparative examples is detailed in Table 1.

TABLE 1

Raw materials	Model number	Source information
			Polymeric aluminum silicate sulfate	/	Environmental protection science and technology Limited, Juan in Qihe county
Polyacrylamide sodium salt	/	Shanxi Chenming Biotechnology Co Ltd
			Sodium silicate	Industrial grade	Jinan Meng Joe chemical Co Ltd
Sodium alginate	Industrial grade	Jiangsu Ofu Biotech Co., Ltd
			Dula fiber	0002	LaiwenkeKai engineering materials Co Ltd
Sulfamate water reducing agent	/	Commercial and commercial Limited of Laiwan Han, Jinan City
			Naphthalene water reducing agent	Wanshan	Shandong Long Cheng ze chemical engineering Co Ltd
Polycarboxylic acid water reducing agent	LA-8Q	Shandong Li-ang New Material science and technology Co Ltd
			Cement	Portland cement	Shi county Huayu geocement manufacturing Co Ltd

Examples

Examples 1 to 3

A rotary drilling bored concrete pile is prepared from concrete mixture including coarse aggregate, fine sand, cement, bentonite, water reducer, aluminium polysilicate sulfate, sodium polyacrylate and sodium silicate.

The coarse aggregate comprises one or more of common crushed stone, broken gravel and regenerated crushed stone; the fine sand is selected from river sand and sea sand; the water reducing agent is one or more of sulfamate water reducing agent, naphthalene water reducing agent and polycarboxylic acid water reducing agent.

The selection and amount of the specific raw materials are shown in Table 2.

The preparation method of the concrete mixture comprises the following steps:

step 1): mixing cement and bentonite, and stirring for 2 minutes at the rotating speed of 48r/min to obtain a primary mixed material.

Step 2): and mixing the primary mixed material with other raw materials except the coarse aggregate, and stirring for 3 minutes at the rotating speed of 55r/min to obtain a secondary mixed material.

Step 3): and mixing the mixed material with the coarse aggregate, and stirring for 3 minutes at the rotating speed of 52r/min to obtain a finished product.

The construction process of the rotary drilling cast-in-place pile comprises the following steps:

step a): the method comprises the steps of leveling and tamping a field, then measuring and setting out, measuring the position of a pile placing hole, and measuring the ground elevation in the field.

Step b): and (3) pile foundation positioning, namely drilling and digging to a set hole depth at a designated position by using a rotary drilling rig, installing a pile casing driver of the rotary drilling rig, lifting a pile casing, aligning the pile casing with a hole position, putting down the pile casing by using a rotary arm rod, and embedding the pile casing.

Step c): the supporting layer can be used for cleaning the hole in detail, and after the supporting layer is used for surveying in detail, the drill bucket is processed to discharge sediments.

Step d): the reinforcement cage is hoisted by a crane and then vertically installed in the borehole.

Step e): and installing a concrete guide pipe in the drill hole.

Step f): and continuously pouring concrete mixture into the reinforcement cage through the concrete guide pipe, standing, and watering and curing for 7 days to obtain the cast-in-place pile.

TABLE 2

Examples 4 to 6

The difference between the rotary drilling bored concrete pile and the embodiment 3 is that sodium alginate is also added into the concrete mixture in the step 2), and the adding amount of the sodium alginate is shown in a table 3.

TABLE 3

Item	Example 4	Example 5	Example 6
				Input amount (kg)	1.9	1.2	1.6

Examples 7 to 9

The difference between the rotary drilling bored concrete pile and the embodiment 3 is that in the step 2), the dola fiber is also added into the concrete mixture, and the amount of the dola fiber added is shown in table 4.

TABLE 4

Item	Example 7	Example 8	Example 9
				Input amount (kg)	5.8	6.5	7.6

Example 10

The difference between the rotary drilling bored concrete pile and the embodiment 3 is that the water reducing agents are sulfamate water reducing agents and naphthalene water reducing agents, and the weight ratio of the sulfamate water reducing agents to the naphthalene water reducing agents is 1:1.2, namely 2.86kg of sulfamate water reducing agents and 3.44kg of naphthalene water reducing agents.

Example 11

The difference between the rotary drilling bored concrete pile and the embodiment 3 is that the water reducing agents are sulfamate water reducing agents and naphthalene water reducing agents, and the weight ratio of the sulfamate water reducing agents to the naphthalene water reducing agents is 1:1.4, namely 2.63kg of sulfamate water reducing agents and 3.67kg of naphthalene water reducing agents.

Example 12

The utility model provides a dig bored concrete pile soon, lies in with embodiment 3 that the coarse aggregate includes ordinary rubble and regeneration rubble, and the weight ratio of ordinary rubble and regeneration rubble is 1: 0.8, namely 502kg of common crushed stone and 402kg of regenerated crushed stone.

Example 13

The utility model provides a dig bored concrete pile soon, lies in with embodiment 3 that the coarse aggregate includes ordinary rubble and regeneration rubble, and the weight ratio of ordinary rubble and regeneration rubble is 1:1.2, namely 410kg of common crushed stone and 494kg of regenerated crushed stone.

Example 14

A rotary drilling bored concrete pile, which is different from embodiment 6 in that,

in the step 2), 7.6kg of dural fiber is also added into the concrete mixture;

the water reducing agent comprises a sulfamate water reducing agent and a naphthalene water reducing agent, and the weight ratio of the sulfamate water reducing agent to the naphthalene water reducing agent is 1: 1.4; the coarse aggregate comprises common crushed stones and regenerated crushed stones, and the weight ratio of the common crushed stones to the regenerated crushed stones is 1: 0.8.

comparative example

Comparative example 1

A rotary excavating bored pile, which is different from embodiment 3 in that polyaluminium silicate sulfate is replaced with an equal amount of common crushed stone.

Comparative example 2

The difference between the rotary drilling bored concrete pile and the embodiment 3 is that sodium polyacrylate is replaced by the same amount of common broken stones.

Comparative example 3

The difference between the rotary drilling bored concrete pile and the embodiment 3 is that sodium silicate is replaced by the same amount of common broken stones.

Performance test

1. And (3) detecting the compressive strength: according to GB/T50081-2019 'test method Standard for physical and mechanical Properties of concrete', examples 1-14 and comparative examples 1-3 are detected, the corresponding concrete mixture is prepared into a 150mm cubic test piece, and the cubic test piece is detected.

2. And (3) detecting the fluidity: slump tests were carried out according to GB/T50080-2002 Standard test methods for Performance of general concrete mixtures for examples 1-14 and comparative examples 1-3.

3. And (3) detecting the impermeability: examples 1 to 14 and comparative examples 1 to 3 are detected according to GB/T50082-2009 test method Standard for Long-term Performance and durability of ordinary concrete, the test block is naturally dried, then the upper surface and the lower surface of the test block are treated by a steel brush to remove a thin cement glue layer, and then the test block is pressed into a die sleeve after being sealed. The water pressure was increased to 1.2MPa within 5min and maintained in this range for 24 h. And then taking out the test block, putting the test block on a press machine, longitudinally splitting the test block into two parts, measuring the water seepage height of 10 measuring points, and taking the average value as the water seepage height of the test block.

The specific assay data for experiments 1-3 are detailed in tables 5-8.

TABLE 5

Categories of	Slump (mm)	Depth of penetration (cm)	28d compressive Strength (MPa)
				Example 1	193	2.66	36.5
Example 2	194	2.63	36.7
				Example 3	196	2.58	36.8
Comparative example 1	178	2.87	32.9
				Comparative example 2	179	2.84	33.5
Comparative example 3	177	2.88	32.6

As shown by comparing the test data of examples 1 to 3 with those of comparative examples 1 to 3 in Table 5, the fluidity of the concrete admixture of examples 1 to 3, the impermeability effect of the concrete obtained, and the compressive strength were all superior to those of comparative examples 1 to 3. The inventor guesses that the concrete has good anti-permeability performance probably because the setting time of the cement is prolonged under the joint action of the polyaluminium silicate sulfate, the sodium polyacrylate and the sodium silicate, and the connection strength among all the substances is enhanced, so that the cast-in-place pile is not easy to break and is not easy to invade by underground water.

TABLE 6

Categories of	Slump (mm)	Depth of penetration (cm)	28d compressive Strength (MPa)
				Example 3	196	2.58	36.8
Example 4	196	2.57	38.3
				Example 5	195	2.58	38.5
Example 6	195	2.56	38.9

As can be seen from the comparison of the test data of example 3 and examples 4-6 in Table 6, the compressive strength of examples 4-6 is greater than that of example 3. The inventor guesses that certain reaction is possibly generated under the cooperation of sodium alginate, sodium polyacrylate and aluminum polysilicate sulfate, so that the compressive strength of the concrete is improved, and the cast-in-place pile has a better compressive effect.

TABLE 7

Categories of	Slump (mm)	Depth of penetration (cm)	28d compressive Strength (MPa)
				Example 3	196	2.58	36.8
Example 7	201	2.49	38.1
				Example 8	203	2.45	38.4
Example 9	204	2.44	38.8

As shown by comparing the test data of example 3 and examples 7-9 in Table 7, the flowability, the impermeability and the compressive strength of examples 7-9 are better than those of example 3. The inventor guesses that after the dola fiber is added, a certain mesh structure is formed under the common cooperation of the dola fiber, the polymeric aluminum silicate sulfate, the sodium polyacrylate and the sodium silicate, so that the fluidity of the concrete mixture and the impermeability of the concrete are improved, and the performance of the cast-in-place pile is improved.

TABLE 8

Categories of	Slump (mm)	Depth of penetration (cm)	28d compressive Strength (MPa)
				Example 3	196	2.58	36.8
Example 10	198	2.55	37.2
				Example 11	200	2.53	37.5
Example 12	197	2.56	37.1
				Example 13	196	2.56	37.0
Example 14	208	2.33	39.4

According to comparison of the detection data of the example 3 and the examples 10 to 11 in the table 8, the sulfamate water reducer and the naphthalene water reducer are mixed in a specific ratio, so that the prepared concrete has better compressive strength and anti-permeability effect, and the flowability of the corresponding concrete mixture is better.

According to the comparison of the test data of example 3 and examples 12-13 in Table 8, the compression resistance effect of the concrete can be improved by matching the common crushed stones and the regenerated crushed stones in a specific ratio.

The present embodiment is only for explaining the present application, and it is not limited to the present application, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present application.

Claims (8)

1. A rotary drilling bored concrete pile is characterized in that the pile is prepared from concrete mixture; the concrete mixture comprises 853-965 parts of coarse aggregate, 486-558 parts of fine sand, 186-198 parts of cement, 25-38 parts of bentonite, 169-178 parts of water, 4.0-8.5 parts of a water reducing agent, 1.9-3.0 parts of polyaluminum silicate sulfate, 2.1-3.5 parts of sodium polyacrylate and 5.3-6.7 parts of sodium silicate in parts by weight.

2. The rotary excavating drilling cast-in-place pile according to claim 1, characterized in that: the concrete mixture also comprises 1.2 to 1.9 weight parts of sodium alginate.

3. The rotary excavating drilling cast-in-place pile according to claim 1, characterized in that: the concrete mixture also comprises 5.8-7.6 parts of Dula fiber.

4. The rotary excavating drilling cast-in-place pile according to claim 1, characterized in that: the water reducing agent is one or more of a sulfamate water reducing agent, a naphthalene water reducing agent and a polycarboxylic acid water reducing agent.

5. The rotary excavating drilling cast-in-place pile according to claim 4, characterized in that: the water reducing agent comprises a sulfamate water reducing agent and a naphthalene water reducing agent, and the weight ratio of the sulfamate water reducing agent to the naphthalene water reducing agent is 1 (1.2-1.4).

6. The rotary excavating drilling cast-in-place pile according to claim 1, characterized in that: the coarse aggregate comprises common crushed stones and regenerated crushed stones, and the weight ratio of the common crushed stones to the regenerated crushed stones is 1: (0.8-1.2).

7. The rotary excavating drilling cast-in-place pile according to any one of claims 1 to 6, characterized in that: the preparation method of the concrete mixture comprises the following steps:

step 1): uniformly mixing cement and bentonite to obtain a primary mixed material;

step 2): uniformly mixing the primary mixed material with other raw materials except the coarse aggregate to obtain a middle mixed material;

step 3): and uniformly mixing the medium mixture and the coarse aggregate to obtain a finished product.

8. The construction process of the rotary drilling bored concrete pile based on any one of claims 1 to 7 is characterized by comprising the following steps:

step a): leveling a field, then measuring and paying off, and measuring the ground elevation in the field;

step b): positioning a pile foundation, drilling and digging the pile foundation to a set hole depth at an appointed position by a rotary drilling rig, and embedding a pile casing;

step c): the supporting layer can be used for cleaning the hole in detail, and after the supporting layer is used for surveying in detail, the drill bucket is processed to discharge sediments;

step d): vertically installing a reinforcement cage into the drilled hole;

step e): installing a concrete guide pipe in the drill hole;

step f): and continuously pouring concrete mixture into the reinforcement cage through the concrete guide pipe, and standing and maintaining to obtain the cast-in-place pile.