CN115573324A - Double-wheel milling deep-mixing cement soil underground continuous wall construction method - Google Patents

Abstract

The invention discloses a double-wheel milling deep mixing cement soil underground continuous wall construction method, which comprises the steps of obtaining the position of an underground continuous wall to be constructed and wall parameters; forming a lead hole at the position of the underground continuous wall to be constructed, backfilling, and determining the parameters of the lead hole according to the wall parameters; and (4) constructing the underground continuous wall which meets the wall parameters by using double-wheel milling deep stirring equipment and cement slurry at the position of the underground continuous wall to be constructed after backfilling the guide hole. According to the double-wheel milling deep mixing cement soil underground continuous wall construction method, the hole leading process is additionally arranged, so that the digging difficulty is reduced when the underground continuous wall encounters a hard stratum with the standard penetration number of more than 40 in the wall forming construction process, the pressure of a hydraulic system in the drilling process is reduced, the service life of construction equipment is prolonged, and the construction speed is increased.

Description

Double-wheel milling deep-mixing cement soil underground continuous wall construction method

Technical Field

The invention discloses a double-wheel milling deep mixing cement soil underground continuous wall construction method, and belongs to the technical field of engineering construction.

Background

The underground continuous wall technology is introduced into China, and is widely applied to foundation engineering as a waterproof curtain, a retaining wall, a seepage-proof wall and the like. With the continuous development of underground engineering, corresponding supporting equipment is updated.

The double-wheel milling deep mixing cement soil underground continuous wall construction method is a well developed technical process at present, has the characteristics of high construction speed, high wall forming quality, high excavation precision, low noise, vibration and the like, is widely applied to underground engineering, obtains obvious social and economic benefits, and has good application and popularization prospects in engineering construction. However, when a hard stratum with the penetration number larger than 40 is encountered, the rotation speed of the milling wheel is reduced in the drilling process of the double-wheel milling deep-stirring device, and the normal rotation of the milling head can be ensured only by keeping the extremely high pressure of the hydraulic system, so that the construction difficulty is high, the construction equipment is easy to damage, and the construction progress is influenced.

Disclosure of Invention

The application aims to provide a double-wheel milling deep mixing cement soil underground continuous wall construction method to solve the technical problem that in the prior art, the cutting pressure of cutting equipment is large due to the fact that the hardness of a hard stratum with the standard penetration number of more than 40 is large. In order to achieve the purpose, the invention provides a construction method for increasing a hole guiding procedure, backfilling a hole guiding and improving the proportion of slurry, and the specific scheme is as follows:

a double-wheel milling deep mixing cement soil underground continuous wall construction method comprises the following steps:

step 1, acquiring the position and wall parameters of an underground continuous wall to be constructed;

step 2, forming a lead hole at the position and backfilling, wherein the parameters of the lead hole are determined according to the wall parameters;

and 3, constructing the underground continuous wall according with the wall parameters by using double-wheel milling deep stirring equipment and cement slurry at the position of the underground continuous wall to be constructed after backfilling the lead holes.

The following further describes the implementation method:

in one embodiment, the opening of the lead hole at the position specifically includes:

determining the longitudinal axis of the underground continuous wall to be constructed;

and a lead hole is formed on the longitudinal axis.

In one embodiment, the opening of the guide hole on the longitudinal axis specifically includes:

a plurality of guide holes which are sequentially distributed are formed in the longitudinal axis, the hole center distance is limited by stratum and cost, and the guide holes are reasonably arranged according to actual conditions.

As an improvement, the lead hole is constructed in the order of jump hole operation.

In one embodiment, the wall parameters include wall depth and wall thickness;

the aperture of the lead hole is consistent with the wall thickness, and the depth of the lead hole is greater than the wall depth.

In one embodiment, the guide hole is backfilled by using notch return slurry which is uniformly stirred and used for constructing the underground continuous wall and undisturbed soil in the guide hole, and the volume ratio of the notch return slurry to the undisturbed soil is 3:1-5:1.

In one embodiment, at the position of the underground continuous wall to be constructed after backfilling the lead hole, constructing the underground continuous wall meeting the wall parameters by using a double-wheel milling deep stirring device and cement slurry, and specifically comprising:

and cutting and stirring the undisturbed soil body on the construction site by using double-wheel milling deep stirring equipment according to the wall parameters at the position of the underground continuous wall to be constructed after backfilling the guide hole, and simultaneously injecting cement slurry and gas into the groove section formed by cutting and stirring to form the equal-thickness cement-soil underground continuous wall.

In one embodiment, the cement slurry has a water-cement ratio of 3 to 4:1.

In one embodiment, the cementitious slurry further comprises bentonite.

In one embodiment, the cement slurry contains 5% to 10% bentonite by mass of the cement slurry.

The underground continuous wall construction method of the embodiment has the following beneficial effects:

(1) Through the arrangement of the guide holes, backfilling and loosening of soil, the digging difficulty of the underground continuous wall is reduced when the underground continuous wall meets a hard stratum (such as a aeolian fine sand stratum) with the penetration number of more than 40 in the wall forming construction process, the pressure of a hydraulic system in the drilling process is reduced, the service life of construction equipment is prolonged, and the construction speed is increased.

(2) The parameters and distribution of the lead holes are set, so that the constructed underground diaphragm wall has more integrity, continuity and uniformity.

(3) The notch slurry return and the original state soil in the guide hole for constructing the underground continuous wall are backfilled into the guide hole, so that hole collapse can be effectively prevented, and the guide hole is protected and the cost for additionally transporting and mixing other backfilled guide hole materials is saved by backfilling the notch slurry return.

(4) The cement slurry containing 5 to 10 percent of bentonite with the water-cement ratio of 3 to 4:1 is poured into the underground continuous wall, so that the initial setting time of the cement slurry is delayed, the water content of the slurry in the groove section is reduced and slowed down, and the method is suitable for the characteristic of long construction time of the underground continuous wall.

Drawings

FIG. 1 is a schematic flow chart of a double-wheel milling deep mixing cement soil underground continuous wall construction method according to an embodiment of the present invention;

FIG. 2 is a schematic view of a via backfill process;

FIG. 3 is a process flow of via backfilling;

FIG. 4 is a set of via arrangements;

fig. 5 shows the positional relationship between the lead holes and the continuous wall.

In the figure: 1. a continuous wall longitudinal axis; 2. guiding holes of the rotary drilling rig; 3. backfilling the small excavator; 4. leading the hole back to be filled; 5. the lap joint position of the continuous wall; 6. a continuous wall; I. a single hole; II, double-hole.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the detailed description and specific examples, while indicating the scope of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.

As shown in fig. 1, in one embodiment, a double-wheel milling deep mixing cement soil underground continuous wall construction method in an aeolian silty fine sand stratum is disclosed, which comprises the following steps:

step 1, obtaining the position and wall parameters of the underground continuous wall to be constructed.

In this embodiment, the position of the underground continuous wall to be constructed is inside a dam body of a certain reservoir, and the construction content in this embodiment is dam body reinforcement and seepage prevention treatment of a water retaining structure. The length of the wall body of the underground continuous wall to be constructed is 730m, the depth of the wall body is 45m, and the thickness of the wall body is 0.7m. The wall parameters used in this embodiment include the wall and wall thickness. And after the position of the diaphragm wall to be constructed and the wall parameters are obtained, measuring and lofting are carried out, and the longitudinal axis of the underground diaphragm wall to be constructed is determined.

And 2, forming a lead hole at the position of the underground continuous wall to be constructed, and backfilling, wherein the parameters of the lead hole are determined according to the wall parameters.

In this embodiment, the through holes are formed at the positions where the underground continuous wall is to be constructed, and the through holes may be randomly distributed in a dotted manner or arranged on the longitudinal axis of the underground continuous wall, preferably, the through holes are arranged on the longitudinal axis, and the arrangement relationship between the through holes and the longitudinal axis of the underground continuous wall as shown in fig. 4 can ensure the continuity, integrity, uniformity and verticality of the underground continuous wall. The parameters of the via include the hole diameter and the hole depth, in the embodiment, the hole diameter of the via is required to be consistent with the wall thickness, and the depth of the via is larger than the wall depth.

When a plurality of guide holes are arranged on the longitudinal axis, hole cores of the guide holes are continuously and sequentially arranged on the longitudinal axis of the underground diaphragm wall at intervals, and the hole core intervals are limited by stratum and cost and are reasonably arranged according to actual conditions. In the embodiment, the hole center interval of the leading holes is 2.5m, the formation is an aeolian fine sand formation, the formation has the characteristic of no cohesive force, the hole distance is not suitable to be too large, and if the hole distance is too small, the hole collapse risk can be increased.

And marking the position of the lead hole after selecting the position of the lead hole, such as spraying a mark at the center of the lead hole or pre-punching the center of the lead hole. The position can be accurately determined conveniently in the subsequent hole guiding process. According to the formation condition in the embodiment, as shown in fig. 2, the hole drilling process uses 5 holes as a group to perform hole jump operation. Namely, a group of guiding holes is divided into two stages, the single-number holes are used as first-stage holes to be guided firstly, and then the rest double-number holes are used as second-stage holes to be guided. To the wind deposit fine sand stratum in this embodiment, the jump hole operation can effectively reduce the hole risk of collapsing.

In this embodiment, before the hole guiding process is performed, a protective cylinder of 3m is arranged below the top of the hole guiding process to protect the hole opening. The protective cylinder can protect the hole opening to prevent sundries such as ground stones and the like from falling into the hole, and guide the drilling direction in the hole leading process.

As shown in fig. 5, in the positional relationship between the hole guiding and the diaphragm wall in this embodiment, the thickness of the diaphragm wall to be constructed in this embodiment is 0.7m, the hole guiding aperture is the same as the diaphragm wall thickness, if the hole guiding aperture is larger than the diaphragm wall thickness, the internal space of the wall slot will be increased, the volume of the wall will be increased, the strength of the wall will be reduced, and if the hole guiding aperture is smaller than the wall thickness, the hole guiding effect will be weakened, and the work efficiency will be reduced. In the embodiment, the depth of the wall of the underground continuous wall to be constructed is 45m, the depth of the hole of the lead hole is 0.5m greater than that of the wall, and the depth of the hole is 45.5m, if the depth of the hole is more than that of the wall, the original stratum at the bottom of the wall can be damaged, and the stability of the wall can be influenced. And selecting a pilot hole drilling machine after the pilot hole aperture and the pilot hole depth are determined, wherein the drilling machine is selected according to indexes such as construction site environment, stratum adaptability, drilling machine hole forming efficiency and the like. In this embodiment, an RTX280 rotary drilling rig is selected for hole guiding.

As shown in fig. 3, in the hole-guiding backfill process, chemical slurry is used for wall protection during the drilling process, and the slurry is very important during the drilling process and plays a role in protecting the hole wall and preventing collapse. The processing after the hole forming of the lead hole is the key of the hole forming process, and if the exposure time is too long, hole collapse can be caused, and the safety of a dam body can be threatened. The guide hole is backfilled to prevent hole collapse, the guide hole filler is particularly important, if undisturbed soil is backfilled, self-compaction can occur under the action of water, the guide hole is invalid, and extra transportation mixing cost can be increased when other fillers are prepared.

In the embodiment, the slot opening returns slurry and undisturbed soil to lead the hole and backfill in the construction process of the underground diaphragm wall, the volume ratio of the slot opening returns slurry to the undisturbed soil is 3:1-5:1, and specifically, the volume ratio of the slot opening returns slurry to the undisturbed soil is 4:1, backfill after stirring misce bene with both, realize returning the cyclic utilization of thick liquid and original state soil, return the thick liquid and can replace downthehole chemical mud because the notch returns thick liquid than great in chemical mud when economic environmental protection, return the thick liquid and set up the thick liquid pond beside the pilot hole, the chemical mud unified treatment that will replace, prevent that chemical mud from polluting underground continuous wall.

As shown in fig. 4, in this embodiment, 5 pilot holes are used as a group to perform hole jumping operation, specifically, a construction team is divided into two groups of operation, one group can complete 3 pilot hole backfilling operations, i.e., complete single-hole operation, and each time one pilot hole is completed, backfilling is performed immediately, and after one group completes single-hole Kong Huitian, the next group performs double-hole operation, and repeats the single-hole operation procedure. In this embodiment, 5 lead holes are set as a group, so that backfill materials can be fully precipitated by using two shift operation intervals after the single hole/double hole is backfilled, and the risk of hole collapse is reduced.

And 3, constructing the underground continuous wall according with the wall parameters by using double-wheel milling deep stirring equipment and cement slurry at the position of the underground continuous wall to be constructed after backfilling the lead holes.

In the embodiment, a double-wheel milling deep mixing cement-soil underground continuous wall construction technology is used after the leading hole is backfilled. And cutting the undisturbed soil body on the construction site by adopting two groups of milling wheels in a horizontal axial rotation stirring mode to form the improved soil body of the rectangular groove section. And (3) injecting cement slurry and gas while milling, cutting, sinking and stirring to construct the equal-thickness cement-soil underground continuous wall.

In the slip casting process, stratum moisture content is lower in because of the construction environment, dado thick liquid skin in the groove section has played the effect of similar pellicle, can hinder solute (cement granule, the motion of the fine sand of powder), but can not block the motion of stagnant water, and the inside and outside moisture content difference of groove section is great, great concentration difference has been formed, lead to water in the thick liquid to disperse in the stratum because of the osmosis, this process of the stirring of cutter head and the generating heat of cement hydration reaction all can aggravate, lead to the very fast reduction of thick liquid moisture content in the groove section, cement is the very fast initial set with the mixture of original state soil, finally lead to the stirring difficulty.

In this example, the water-cement ratio was adjusted to 3:1 for improving the water content of the slurry and preventing the water content of the slurry in the groove section from being rapidly reduced. Bentonite to be simultaneously incorporated in the cement paste, wherein water: cement: the bentonite is 3. Can effectively prevent the rapid evaporation of water and delay the initial setting time of cement paste so as to further solve the problems of rapid reduction of the water content of the slurry in the groove section, long construction time and the like in the aeolian fine sand stratum.

In the embodiment, the guide holes are arranged and backfilled to loosen soil, so that the digging difficulty of the double-wheel milling deep stirring equipment is reduced when the double-wheel milling deep stirring equipment encounters a hard stratum (such as a aeolian fine sand stratum) with the standard penetration number being more than 40 in the wall forming construction process, the pressure of a hydraulic system in the drilling process is reduced, the service life of construction equipment is prolonged, and the construction speed is increased.

The above embodiments are merely representative of one real-time aspect of the present invention, and the description thereof is more specific and detailed, but should not be construed as limiting the scope of the invention. It should be noted that various changes and modifications can be made by those skilled in the art without departing from the spirit of the invention, and these changes and modifications are all within the scope of the invention. Therefore, the protection scope of the present patent should be subject to the appended claims.

Claims (10)

1. A double-wheel milling deep mixing cement soil underground continuous wall construction method is characterized by comprising the following steps:

acquiring the position and wall parameters of an underground continuous wall to be constructed;

forming a lead hole at the position and backfilling, wherein the parameters of the lead hole are determined according to the wall parameters;

and (3) utilizing a double-wheel hydraulic milling and stirring drilling machine and cement slurry at the position of the underground continuous wall to be constructed after the backfilling of the guide hole to construct the underground continuous wall according with the wall parameters.

2. The double-wheel milling deep mixing cement soil underground continuous wall construction method according to claim 1, wherein a lead hole is formed at the position, and the method specifically comprises the following steps:

determining the longitudinal axis of the underground continuous wall to be constructed;

and a lead hole is formed on the longitudinal axis.

3. The double-wheel milling deep mixing cement soil underground continuous wall construction method is characterized in that the hole leading is constructed in the hole jumping operation sequence.

4. The double-wheel milling deep mixing cement soil underground continuous wall construction method according to claim 1, wherein the wall parameters include wall depth and wall thickness;

the aperture of the lead hole is consistent with the wall thickness;

the depth of the lead hole is greater than the depth of the wall.

5. The method for constructing a double-wheel milling deep mixing cement-soil underground continuous wall as claimed in claim 1, wherein the backfill used for backfilling the pilot hole comprises a notch grout return for constructing the underground continuous wall and undisturbed soil in the pilot hole.

6. The double-wheel milling deep mixing cement soil underground continuous wall construction method as claimed in claim 5, wherein the volume ratio of the notch slurry return to the undisturbed soil in the lead hole is 3:1-5:1.

7. The method for constructing the underground continuous wall by deep mixing cement soil through double milling according to any one of claims 1 to 6, wherein the construction of the underground continuous wall according with the wall parameters by using the double milling deep mixing equipment and cement grout at the position of the underground continuous wall to be constructed after backfilling the lead holes comprises the following specific steps:

and cutting and stirring the undisturbed soil body at the position of the underground continuous wall to be constructed after the hole is backfilled by using double-wheel milling deep stirring equipment according to the wall parameters, and simultaneously injecting cement slurry and gas into the groove section formed by cutting and stirring to construct the equal-thickness cement-soil underground continuous wall.

8. The method for manufacturing a cement-soil underground continuous wall by deep mixing through double-wheel milling according to claim 7, wherein the cement slurry has a water-cement ratio of 3 to 4:1.

9. The method of claim 8, wherein the cement slurry further comprises bentonite.

10. The method for manufacturing a cement-soil underground continuous wall through deep mixing by using a double-wheel mill as claimed in claim 9, wherein the cement slurry contains bentonite in an amount of 5-10% by mass of the cement slurry.

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