CN111778968A

CN111778968A - Construction method of high-content fly ash-based occlusive pile for waterproof curtain

Info

Publication number: CN111778968A
Application number: CN202010601036.0A
Authority: CN
Inventors: 董书宁; 王海; 王皓; 姬亚东; 石磊; 黄选明; 王晓东; 曹海东
Original assignee: Xian Research Institute Co Ltd of CCTEG
Current assignee: Xian Research Institute Co Ltd of CCTEG
Priority date: 2020-06-29
Filing date: 2020-06-29
Publication date: 2020-10-16

Abstract

A construction method of a high-doped fly ash-based secant pile for a waterproof curtain is characterized in that a rotary drilling rig is adopted for secant pile construction, secant piles are mutually secant and enter a waterproof clay layer or a mud rock layer, a high-doped fly ash-based grouting material is poured into the secant pile, and I-shaped steel is intermittently inserted into the secant pile to form a continuous secant pile wall body serving as an anti-seepage waterproof curtain; the method can effectively solve the problems of low hole forming speed, complex and complicated pouring process, mud precipitation, high cost of pouring concrete and large requirement on a construction site of the occlusive pile, and improves the continuity and the seepage-proofing performance of the water-blocking curtain while solving the problems of low construction efficiency, high cost, large construction site and the like.

Description

Construction method of high-content fly ash-based occlusive pile for waterproof curtain

Technical Field

The invention relates to the technical field of underground water blocking, seepage prevention and pollution control such as mine curtains, hydraulic engineering curtains, pollutant isolation, foundation pit water-stopping curtains and the like, in particular to a construction method of a high-content fly ash-based secant pile for a water-blocking curtain.

Background

As a mature process, if construction needs to use ultra-retarding concrete and a full-casing drilling machine, the construction cost is particularly high, the cost is almost 2 times of that of the underground diaphragm wall with the same thickness, and the hole forming speed is slow and is 2 times of the hole forming time of a common cast-in-situ bored pile. The construction process of the secant pile in the deep sandy gravel stratum is different from that of other stratums, and the following problems exist in the prior art when a water-blocking curtain is constructed and constructed in the deep sandy gravel stratum: 1. the underground diaphragm wall can meet the water stop requirement but has high construction cost, 2, the ultrahigh pressure angular region variable speed swing spraying process is complex, the construction cost is high, the construction efficiency is low, 3, drilling and grouting are difficult, the continuity of a curtain is poor, grouting is uncontrollable, and 4, the traditional occlusive pile has high construction cost, low hole forming speed, complex occlusive pile pouring process and difficult construction in a narrow field.

Therefore, in view of the above-mentioned drawbacks, the present inventors have conducted extensive research and design to overcome the above-mentioned drawbacks by designing a method for constructing a high-content fly ash-based occlusive pile for a water-blocking curtain, which combines the experience and results of the related industries for many years.

Disclosure of Invention

The invention aims to provide a construction method of a high-content fly ash-based occlusive pile for a water-blocking curtain, which can effectively solve the problems of low hole forming speed, complicated and complex pouring process, mud precipitation, high cost of concrete pouring and large construction site requirement of the occlusive pile, and improve the continuity and the anti-seepage performance of the water-blocking curtain while solving the problems of low construction efficiency, high cost, large construction site and the like.

To achieve the above object, the present invention discloses

From the above, the construction method of the high-content fly ash-based occlusive pile for the water-blocking curtain has the following effects:

1. the construction method of the high-content fly ash-based secant pile for the waterproof curtain is simple in process, simple to operate, practical and reliable.

2. The high-doping-amount fly ash-based slurry mainly comprises fly ash, cement, clay, bentonite, an additive and the like, the doping amount of the fly ash is large and reaches more than 50%, the conventional concrete is replaced, and the high-doping-amount fly ash-based slurry is economical, green and environment-friendly. The slurry is slowly condensed, the early strength is low, the occlusive construction of the occlusive pile is facilitated, the pore-forming verticality is easy to control, the later strength of the slurry stone body is increased, and the impermeability is good.

3. The grouting pipe replaces a steel guide pipe which is complex in process, inconvenient to operate and needs to be mechanically hoisted, and the fiber bragg gratings continuously distributed in the grouting pipe can monitor the stress strain and temperature change conditions in the occlusive pile, so that real-time data are provided for the construction quality detection and the operation period monitoring of the waterproof curtain. The pipe orifice quick connector is connected with the ground slurry conveying pipe, can realize quick connection and quick disassembly, and is simple and convenient to operate.

4. The I-shaped steel is inserted into the occlusive pile to replace the traditional reinforcement cage, so that the bending resistance and the deformation resistance of the waterproof curtain are improved, the construction operation is simple and rapid, and the cost is low.

The details of the present invention can be obtained from the following description and the attached drawings.

Drawings

FIG. 1 shows a schematic plan view of a highly-loaded fly ash-based bite pile water-blocking curtain of the present invention.

Fig. 2 shows a schematic diagram of the construction of the high-content fly ash-based secant pile in the invention.

Fig. 3 shows a schematic diagram of the dowel of the high-content fly ash-based secant pile of the invention.

FIG. 4 shows a cross-sectional view of a water-blocking curtain of a highly-doped fly ash-based bite pile of the present invention.

Reference numerals:

1. the waterproof curtain comprises 2 parts of an occlusive pile, 3 parts of an occlusive pile occlusive section, 4 parts of a grouting pipe, 5 parts of high-doped fly ash base slurry, 6 parts of I-shaped steel, I-shaped piles, I-shaped occlusive piles, II-shaped occlusive piles, III-shaped occlusive piles and III-shaped occlusive piles.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to specific embodiments and the accompanying drawings. In which like parts are designated by like reference numerals.

Referring to fig. 1 to 4, there is shown a method of constructing a high content fly ash based bite pile for a water blocking curtain according to the present invention.

The construction method of the high-doped fly ash-based secant pile for the waterproof curtain adopts a rotary drilling rig to construct the secant pile, the secant piles are mutually meshed and enter a waterproof clay layer or a mud rock layer, a high-doped fly ash-based grouting material is poured into the secant pile, and I-shaped steel is intermittently inserted into the secant pile to form a continuous secant pile wall body serving as the impermeable waterproof curtain, and the construction method can comprise the following steps:

the method comprises the following steps: and (3) exploring the hydrogeological engineering geological conditions of the site, and finding out the hydrogeological conditions, the engineering geological conditions, the types and the ranges of pollutants of the site by adopting methods such as field reconnaissance, geophysical prospecting, drilling, field tests, indoor tests and the like.

Step two: the construction preparation comprises the steps of determining the plane position, the vertical depth, the top-bottom position, the diameter and the length of an occlusive pile hole of a waterproof curtain 1 according to hydrogeology and engineering geological conditions of a waterproof curtain construction site, measuring and setting out the position of the occlusive pile hole on the site according to the requirement of the waterproof curtain, setting out the ground position of the waterproof curtain, wherein the ground position can be linear, rectangular or circular, the protected area or the pollutant diffusion area is enclosed in a limited range, hydraulic connection on two sides of the waterproof curtain is isolated, the position of a drilling hole is measured and set out according to the determined position of the waterproof curtain, and the hole position error is controlled within 2 cm.

Step three: as shown in figure 1, a rotary drilling rig is adopted to construct sequential holes I-1, I-2, I-3 and … … of an occlusive pile 2 at the position of a water-blocking curtain 1, the pile diameter of the occlusive pile can be 600mm, 800mm or 1000mm, the depth reaches the designed depth, and the bottom of the occlusive pile is generally positioned in a water-resisting layer to enclose a foundation pit, a pollutant diffusion area, an open pit or a well mine. Specifically, it may comprise: the rotary drilling rig is in place, the drilling tool is aligned with the drilling hole, the power head is started, the drilling tool drills downwards, chemical slurry is filled into the hole to replace traditional bentonite or clay slurry, the drilling tool is lifted, the shovel head brings rock-soil mass to the hole opening and stacks on one side of the waterproof curtain, and vehicles are transported and pulled away.

Step four: as shown in figure 2, a grouting pipe 4 is arranged in a sequential hole I-1, I-2, I-3 and … … of an occlusive pile 2, the grouting pipe 4 is a hose, is light in weight and convenient to arrange in the hole, has small construction space requirement and does not need large-scale mechanical hoisting, a distributed fiber bragg grating is embedded in the grouting pipe 4, the stress strain of the occlusive pile 2 can be monitored in real time, the integrity of a pile body can be detected, a sound measuring pipe with complicated procedures is replaced, the sound measuring pipe is generally a metal pipe with the inner diameter not less than 40mm and the wall thickness not less than 3mm, the lower end of the sound measuring pipe is closed, the upper end of the sound measuring pipe is covered, no foreign matter is arranged in the pipe, the sound measuring pipe is embedded in the pile body in advance, and the quality of the pile body is detected after. The grouting pipe is sunk to the bottom of the hole under the action of the balance weight, and the traditional heavy concrete steel guide pipe which is fussy to connect is replaced; taking a deep hole of 40m as an example, the traditional steel guide pipe needs 1 hour for 3 persons to operate and lower under the cooperation of a crane; and the process of putting down the filling pipeline 4 does not need the cooperation of a crane, 1 person operates, the putting down time is only 5min, and about 55min is saved.

Step five: as shown in figure 2, high-doped fly ash-based slurry 5 is poured into holes I-1, I-2, I-3 and … … in the sequence of the occlusive pile 2 through a grouting pipe 4 to form an occlusive pile body with continuous up and down in the holes, the water-solid ratio of the high-doped fly ash-based slurry is 0.7:1.0, and cement: the fly ash is 4:6, bentonite and other additives are added, the cement is P.O 42.5 ordinary portland cement, the fly ash is II-grade or above dry ash of a power plant, the initial setting time of slurry is 14h, the final setting time is 17h,the fluidity is 26cm, the 3d strength is only 0.7MPa, the occlusive construction of the occlusive pile is facilitated, the 7d strength is 1.5MPa, the 28d strength is 4.0MPa, the 60d strength is 5.3MPa, the 120d strength is 11.0MPa, the 250d strength is 13.2MPa, the later strength is higher, and the permeability coefficient reaches 10^-9m/s, good anti-permeability performance. The cost of the high-doped fly ash base slurry 5 is saved by 40.0 percent and 50.0 percent respectively compared with that of plastic concrete and C30 concrete, wherein the slurry has long initial setting time and low early strength, is convenient for the occlusion construction of a subsequent occlusion pile, and a grouting pipe can be left in the pile to be used as a pile body quality detection device after grouting is finished; and the traditional steel conduit needs to be pulled out again after the pouring is finished, and taking the hole depth of 40m as an example, the steel conduit needs to be pulled out for more than 1 hour by 3 persons under the cooperation of a lifting machine. The working time is saved by more than 1 hour in the tube drawing process.

Step six: and (3) as shown in the figures 1 and 2, repeating the steps (two) to (five), measuring the two-sequence holes II-1, II-2, II-3 and … … of the occlusive pile 2 at the position of the waterproof curtain 1, constructing the two-sequence holes II-1, II-2, II-3 and … … of the occlusive pile 2 by adopting a rotary drilling rig, putting a grouting pipe 4, and pouring high-content fly ash base slurry 5 to complete the construction of the two-sequence holes of the occlusive pile 2.

Step seven: as shown in fig. 1, 2 and 3, after the grout of the first-order pile and the second-order pile of the occlusive pile 2 is finally set and the strength is lower than 1MPa, repeating the steps (two) -five) to measure and set the three-order holes III-1, III-2, III-3 and … … of the occlusive pile 2 at the position of the water-blocking curtain 1, constructing the three-order holes III-1, III-2, III-3 and … … of the occlusive pile 2 by adopting a rotary drilling rig, wherein the occlusion of the three-order holes of the occlusive pile 2 with the first-order pile and the second-order pile of the occlusive pile 2 is not less than 0.3m, putting a grouting pipe 4, pouring a high-doped fly ash base grout 5 and inserting I-steel 6 to complete the construction of the three-order pile of the occlusive pile 2. Wherein, the preferred meshing of the three-sequence meshing and the first-sequence and second-sequence meshing piles is not less than 0.3m, and the pile body stress formula_max＝M_max/(β W) know that (among them)_maxMaximum pile shaft stress, M_maxThe maximum bending moment of the occlusive pile, β -the reduction coefficient of the cross section resistance of the occlusive pile, W-the cross section resistance moment of the I-steel), the I-steel increases the bending resistance of the occlusive pile and improves the horizontal bearing capacity of the waterproof curtain until all three-sequence occlusion construction is completedThus, a continuous waterproof curtain of the secant pile is formed, and the bending resistance and the deformation resistance of the waterproof curtain are greatly improved.

Step eight: as shown in fig. 4, the first-order pile, the second-order pile and the third-order pile of the occlusive pile 2 form a continuous water-blocking curtain, the water-blocking curtain penetrates into the water-proof stratum mudstone for 2m, the water-blocking curtain effectively isolates the inside and the outside of the curtain from hydraulic connection, the water level inside the water-blocking curtain drops to a designed position, and the water level outside the water-blocking curtain rises to an ecological water level, so that the vegetation growth is guaranteed. And I-shaped steel is inserted into the three-sequence piles, so that the overall bending resistance, folding resistance and deformation resistance of the waterproof curtain are improved, and the safety of the waterproof curtain is ensured.

Therefore, the invention has the advantages that:

1. simple process, simple operation, practicality, reliability, economy and reasonability.

3. The grouting hose replaces a steel conduit which is complicated in process, inconvenient to operate and needs to be mechanically hoisted, and the fiber bragg gratings continuously distributed in the grouting hose can monitor the stress strain and temperature change conditions in the occlusive pile, so that real-time data are provided for the construction quality detection and the operation period monitoring of the waterproof curtain. The pipe orifice quick connector is connected with the ground slurry conveying pipe, can realize quick connection and quick disassembly, and is simple and convenient to operate.

4. The I-shaped steel is inserted into the occlusive pile to replace the traditional reinforcement cage, so that the bending resistance, the folding resistance and the deformation resistance of the waterproof curtain are improved, the construction operation is simple and rapid, and the cost is low.

It should be apparent that the foregoing description and illustrations are by way of example only and are not intended to limit the present disclosure, application or uses. While embodiments have been described in the embodiments and depicted in the drawings, the present invention is not limited to the particular examples illustrated by the drawings and described in the embodiments as the best mode presently contemplated for carrying out the teachings of the present invention, and the scope of the present invention will include any embodiments falling within the foregoing description and the appended claims.

Claims

1. A construction method of a high-content fly ash-based secant pile for a waterproof curtain is characterized by comprising the following steps:

the method comprises the following steps: carrying out exploration on site hydrogeological engineering geological conditions, and finding out site hydrogeological conditions, engineering geological conditions, pollutant types and ranges;

step two: construction preparation, namely determining the plane position, vertical depth, top and bottom position, secant pile diameter and secant section length of a water-blocking curtain according to hydrogeology and engineering geological conditions of a water-blocking curtain construction site, and measuring and setting out the position of a secant pile hole;

step three: constructing a secant pile first-order hole at the position of the waterproof curtain by adopting a rotary drilling rig, wherein the pile diameter of the secant pile is 600mm, 800mm or 1000mm, the depth reaches the design depth, and a foundation pit, a pollutant diffusion area, an open pit or a well mine are enclosed;

step four: a grouting pipe is put into the first-order hole of the occlusive pile;

step five: pouring the high-content fly ash-based slurry into a first-order hole of the occlusive pile through a grouting pipe to form an occlusive pile body which is continuous up and down in the hole;

step six: repeating the step (II) to the step (V), measuring and determining a second-order hole of the secant pile at the position of the waterproof curtain, constructing the second-order hole of the secant pile by adopting a rotary drilling rig, putting a grouting pipe, and pouring high-content fly ash base slurry to complete the construction of the second-order hole of the secant pile;

step seven: and (3) repeating the steps (two) to (five) when the strength is lower than 1MPa after the slurry of the first-order pile and the second-order pile of the occlusive pile is finally set, measuring and setting out at the position of the waterproof curtain to determine a three-order hole of the occlusive pile, inserting a grouting pipe, pouring high-doped fly ash base slurry, and inserting I-steel to complete the three-order pile construction of the occlusive pile.

2. The method for constructing a high content fly ash based bite pile for a water-blocking curtain as claimed in claim 1, wherein: the grouting pipe is a hose, and the distributed fiber bragg grating is embedded in the grouting pipe, so that the stress strain of the secant pile can be monitored in real time, and the integrity of a pile body can be detected.

3. The method for constructing a high content fly ash based bite pile for a water-blocking curtain as claimed in claim 1, wherein: the water-solid ratio of the high-doped fly ash-based slurry is 0.7:1.0, cement: the fly ash is 4:6, the cement is P.O 42.5 ordinary portland cement, the fly ash is II-grade or above dry ash of a power plant, the initial setting time of the slurry is 14h, the final setting time is 17h, and the fluidity is 26 cm.

4. The method for constructing a high content fly ash based occlusive pile for a water-blocking curtain as claimed in claim 3, wherein: the 3d strength is only 0.7MPa, the 7d strength is 1.5MPa, the 28d strength is 4.0MPa, the 60d strength is 5.3MPa, the 120d strength is 11.0MPa, the 250d strength is 13.2MPa, and the permeability coefficient reaches 10^-9m/s。

5. The method for constructing a high content fly ash based bite pile for a water-blocking curtain as claimed in claim 1, wherein: and the occlusion of the three-sequence holes of the injection occlusive piles and the first-sequence piles and the second-sequence piles of the occlusive piles is not less than 0.3 m.

6. The method for constructing a high content fly ash based bite pile for a water-blocking curtain as claimed in claim 1, wherein: further comprises the following step eight: the first-order pile, the second-order pile and the third-order pile of the occlusive pile form a continuous water-blocking curtain, the water-blocking curtain penetrates into water-proof stratum mudstone for 2m, the water-blocking curtain effectively isolates the inside and the outside of the curtain in hydraulic connection, the water level inside the water-blocking curtain drops to a designed position, the water level outside the water-blocking curtain rises to an ecological water level, and vegetation growth is guaranteed.