CN113668556A

CN113668556A - Double-row pile supporting method for adding connecting beams in soil layer

Info

Publication number: CN113668556A
Application number: CN202110896417.0A
Authority: CN
Inventors: 刘东轩; 张效荣; 张国; 冯祎; 王骄骄
Original assignee: Shenzhen Shengye Construction Technology Group Co ltd
Current assignee: Shenzhen Shengye Construction Technology Group Co ltd
Priority date: 2021-08-05
Filing date: 2021-08-05
Publication date: 2021-11-19

Abstract

The invention discloses a double-row pile supporting method for adding connecting beams in a soil layer, which comprises the steps of pre-burying PVC pipes on front-row piles at intervals from top to bottom and constructing double-row piles; excavating earthwork layer by layer at the position of the pre-buried PVC pipe; drilling; and driving the anchor rod into the rear row of piles and grouting. The method is characterized in that PVC pipes are reserved on the front row piles, and connecting beams are arranged between the front row piles and the rear row piles in two drilling and digging modes of two drilling machines, namely an anchor rod drilling machine and a jet grouting drilling machine, and anchor rod concrete or anchor rod cement soil connecting beams are designed between the double row piles, so that the front row piles and the rear row piles of the double row piles can be cooperatively stressed uniformly, the integral bearing capacity of the double row piles is improved, and the supporting depth can reach 20-30 m. And the support construction method is safe, environment-friendly and high in economic benefit.

Description

Double-row pile supporting method for adding connecting beams in soil layer

Technical Field

The invention relates to a double-row pile supporting method, in particular to a double-row pile supporting method for adding connecting beams in a soil layer.

Background

At present, the maximum depth of a foundation pit supported by double rows of piles is not more than 16 meters, but the number of layers of basements is increased continuously due to the fact that the land used in large and medium cities is more and more tense, the depth of the foundation pit is synchronously deepened, and the depth can reach 20 m-30 m. For the situation that anchor cables are not allowed to be driven on the periphery of a site of a deep foundation pit, the single-row pile anchor supporting mode hardly meets the supporting requirement, and double-row pile supporting is adopted as a better supporting mode. The double-row pile support can also replace single-row piles and horizontal inner supports in pits, so that earthwork excavation and basement main structure construction are facilitated, and the support effect is greatly improved. However, most of the existing double-row pile supporting methods only add a reinforced concrete connecting beam on the pile top, and the pressure of the rear row pile is transmitted to the front row pile through the soil between the piles. The method which only depends on the soil transmission among the piles can generate unstable support due to the geological conditions of the construction site, namely the complex diversity of the soil quality, wherein the soil quality of the construction site is dense cohesive soil, or loose miscellaneous filling soil, soft soil layer, mucky soil or gravel soil. When meeting the soil layers, the stress of the back row pile is maximum, and the pressure can be transmitted to the front row pile through the soil layers after the deformation of the pile body is maximum. The middle stress stage is transmitted to the front row pile through the connecting beam of the pile top, and the front row pile is acted by concentrated force on the pile top, namely the front row pile is acted by the worst load, and at the moment, the bending moment borne by the front row pile is the largest, and the generated deformation is also the largest. Therefore, the common double-row piles can not meet the construction requirements of the deep foundation pit.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention provides a double-row pile supporting method for arranging a plurality of layers of connecting beams between double-row piles in a pre-buried PVC pipe and two reaming modes.

The technical scheme adopted by the invention for solving the technical problems is as follows: a double-row pile supporting method for adding connecting beams in a soil layer comprises the following steps:

the method comprises the following steps: pre-burying PVC pipes on the front row of piles at intervals from top to bottom and constructing double rows of piles;

step two: excavating earthwork layer by layer along the position of the embedded PVC pipe;

step three: drilling;

step four: and (5) driving the anchor rod into the rear row of piles and grouting.

As an improvement of the above technical solution, the concrete processes of drilling, bolting and grouting in the third step and the fourth step are as follows:

A. drilling holes from the PVC embedded pipes by using an anchor rod drilling machine;

B. drilling an anchor rod hole by using a rock drill bit when the rear row of piles are drilled, and penetrating through the rear row of piles;

C. after the rear row of piles are drilled, a hole expanding drill bit is adopted to expand the hole of the soil section between the two piles;

d: driving the pipe seam type anchor rod into the front row pile and the rear row pile;

e: and inserting a mortar conveying guide pipe from the pre-buried PVC pipe orifice for grouting.

As a further improvement of the technical scheme, in the process D, after the anchor rod is driven into the back row of piles, the outer end of the tube seam type anchor rod is locked on the wale by using a nut and a cushion iron plate.

As a further improvement of the technical scheme, mortar or concrete is poured into the hole by a mortar pump during grouting in the process E, and the guide pipe is drawn out while pouring.

As a further improvement of the above technical solution, the concrete processes of drilling, bolting and grouting in the third step and the fourth step are as follows:

A. drilling holes from the PVC embedded pipes by adopting a jet grouting pile drilling machine;

c: the rotary spraying drilling machine is arranged in a soil section between the tail section of the drill hole and the two piles, and high-pressure water flow is used for rotary spraying and cutting soil bodies in the corresponding range of the locking anchoring head and the connecting beam section;

d: after the cutting reaches the design size, the jet grouting drilling machine injects cement paste, and the drill rod is withdrawn while injecting;

e: driving a steel bar anchor rod into the rear row pile from the front row pile;

f: and inserting a grouting pipe from the pre-buried PVC pipe orifice to perform secondary grouting of cement slurry.

As a further improvement of the technical scheme, the tail part of the rotary jet drilling machine is changed into normal-pressure guniting at the inner section of the rear row pile hole during grouting in the process D, and high-pressure guniting is adopted during guniting at the soil layer section.

As a further improvement of the above technical scheme, in the process E, after the steel bar anchor rod is driven into the rear row of piles, the outer end of the steel bar anchor rod is locked on the wale by using a nut and a cushion iron plate, and positioning steel bars for centering the anchor rod are further arranged at the inner ends of the front row of piles and the rear row of piles.

As a further improvement of the technical scheme, the front row of piles and the rear row of piles are arranged in a plurality, and the front row of piles and the rear row of piles are longitudinally aligned one by one along the foundation pit during construction.

As a further improvement of the technical scheme, the PVC pipes are fixed on the reinforcement cages of the front row of piles, two ends of each PVC pipe are sealed, the positions of the PVC pipes are equal to the intervals of the waist beams arranged in the foundation pit along the vertical intervals, and the orifices of the PVC pipes face the foundation pit.

The beneficial effects are that: the double-row pile supporting method is characterized in that PVC pipes are reserved on front row piles, connecting beams are arranged between the front row piles and rear row piles in two drilling and digging modes of two drilling machines, namely an anchor rod drilling machine and a jet grouting drilling machine, anchor rod concrete or anchor rod cement connecting beams are designed between the double row piles, so that the front row piles and the rear row piles of the double row piles can be cooperatively and consistently stressed, the integral bearing capacity of the double row piles is improved, and the supporting depth can reach 20-30 m. And the support construction method is safe, environment-friendly and high in economic benefit.

Drawings

The invention is further illustrated with reference to the following figures and examples.

FIG. 1 is an overall construction flow diagram of the present invention;

FIG. 2 is a flow chart of the present invention for a tube seam anchor and reamed concrete coupling;

FIG. 3 is a flow chart of the present invention for the concrete-added rotary-spraying pile-soil connecting beam of the steel bar anchor rod;

FIG. 4 is a cross-sectional view of the tube seam anchor and reamed concrete coupling of the present invention;

fig. 5 is a cross-sectional view of the cement jet grouting pile and anchor connecting beam of the present invention.

1. Front row piles; 2. back row piles; 3. a tube seam anchor rod; 4. a steel bar anchor rod; 5. a wale.

Detailed Description

The conception, the specific structure, and the technical effects produced by the present invention will be clearly and completely described below in conjunction with the embodiments and the accompanying drawings to fully understand the objects, the features, and the effects of the present invention. It is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments, and those skilled in the art can obtain other embodiments without inventive effort based on the embodiments of the present invention, and all embodiments are within the protection scope of the present invention. In addition, all the connection/connection relations referred to in the patent do not mean that the components are directly connected, but mean that a better connection structure can be formed by adding or reducing connection auxiliary components according to specific implementation conditions. All technical characteristics in the invention can be interactively combined on the premise of not conflicting with each other.

Referring to fig. 1 and 2, during construction, if some projects have important buildings around the plot or are very close to the subway, the anchor cables cannot be constructed due to site conditions, and the anchor cables can be replaced by double rows of piles. The invention provides a double-row pile supporting method for adding connecting beams in a soil layer, which comprises the following steps:

the method comprises the following steps: in order to avoid drilling the pile body concrete of the front row of piles 1 again when driving an anchor rod hole and save labor cost and mechanical cost, PVC pipes are pre-embedded on the front row of piles 1 from top to bottom at certain intervals, double rows of piles are constructed, the interval of the pre-embedded PVC pipes is determined according to design calculation and is generally 1.2-3.0 m, the pipe diameter of the pre-embedded PVC pipes is 100-150 mm, the PVC pipes are fixed on a reinforcement cage during pre-embedding, the PVC pipes are guaranteed not to run and deviate, two ends of the PVC pipes are tightly sealed by rubber covers to prevent concrete from flowing in, the vertical interval of the positions of the PVC pipes is equal to the interval of waist beams arranged in a foundation pit, and an orifice of the PVC pipe faces the foundation pit;

step three: drilling a connecting beam once after excavating a layer of earthwork;

step four: the anchor rods are driven into the rear row of piles 2 and grouted.

Front row pile 1 and back row pile 2 all are equipped with a plurality ofly, and a plurality of front row piles 1 and back row pile 2 are vertically aligned one by one along the foundation ditch when being under construction, and the stake interval is 3 ~ 5 times of stake footpath, and except setting up the pile bolck crown beam on ground between every group front row pile 1 and back row pile 2, still be equipped with even roof beam between front row pile 1 and back row pile 2. By additionally arranging rigid connecting beams such as concrete, cement and the like, the pressure of the rear row of piles 2 is transmitted to the front row of piles 1 from the connecting beams, and the connecting beams bear the pressure under the general condition, so that the characteristic of good compressive property of the concrete is fully utilized when the concrete connecting beams are manufactured. However, when the soil between piles is loose soft soil, the thrust generated when the soil around the connecting beam is close to collapse acts on the front row of piles 1, at the moment, the connecting beam bears the tension, and the rear row of piles 2 connected with the front row of piles 1 through the connecting beam pull the front row of piles 1 through the connecting beam, so that the whole supporting system is kept stable. And the anchor rod is additionally arranged in the coupling beam under the complex geological condition, so that the tensile force bearing capacity of the coupling beam can be improved, the coupling beam is not easy to break, the anchor rod can also be used as a fulcrum of the waist beam 5, and the additional process of drilling the anchor rod of the waist beam 5 is omitted.

Anchor rod concrete or anchor rod cement soil connecting beams are designed between the double-row piles, so that the front and rear row piles 2 of the double-row piles can be cooperatively stressed consistently, the overall bearing capacity of the double-row piles is improved, and the supporting depth can reach 20-30 m. And the support construction method is safe, environment-friendly and high in economic benefit. The supporting mode of double-row piles and connecting beams can completely replace or partially replace supports, horizontal inner supports are cancelled at the central position of the periphery of a foundation pit partially, and only 4 corner supports are reserved. The construction progress of the main body is accelerated on the whole, and the economic benefit is increased. The cement soil or the fine aggregate concrete and the mortar connecting beam are additionally arranged in the soil layer in the double-row pile system, so that the cost required to be increased is little, but the obtained economic benefit and social benefit are very obvious, namely, the investment is small, the effect is quick, and the double-row pile system is safe and environment-friendly.

And the concrete processes of drilling, bolting and grouting in the third step and the fourth step are two modes, namely a construction mode of adding a hole expansion concrete connecting beam to the pipe seam type anchor rod 3 and a construction mode of adding cement to the reinforced anchor rod 4 and jet-grouting pile soil connecting beam in a rotary mode, the two construction modes enable the support to be selected according to different construction site soil conditions and different construction requirements, and the diversity and flexibility of the double-row pile connecting beam support are improved.

3 body of rod ultimate stretching resistance of pipe seam formula stock is greater than 110KN, and just anchorage force is greater than 25KN/m, and the concrete process that adopts pipe seam formula stock 3 to add the construction mode of reaming concrete even roof beam is:

B. drilling an anchor rod hole by using a rock drill bit when the rear row pile 2 is drilled, penetrating the rear row pile 2, and drilling a hole on the rear row pile 2, wherein the hole diameter is matched with the designed pipe seam type anchor rod 3 and is generally 2-5 mm smaller than the diameter of the pipe seam type anchor rod 3;

C. after the rear row of piles 2 are drilled, a hole expanding drill bit is adopted to expand the hole of the soil section between the two piles, the hole expanding drill bit is replaced during expanding the hole, and the hole diameter of the soil section between the piles is expanded to 300-500 mm;

d: driving a pipe seam type anchor rod 3 into a back row pile 2 from a front row pile 1, and locking the outer end of the pipe seam type anchor rod 3 on a wale 5 by using a nut and a cushion iron plate after the anchor rod is driven into the back row pile 2;

e: and inserting a mortar conveying guide pipe from the pre-buried PVC pipe orifice for grouting, pouring mortar or concrete into the hole by a mortar pump during grouting, drawing out the guide pipe while pouring until the hole is full, and paying attention to plugging the orifice during pouring to prevent slurry leakage.

The concrete process of the construction mode of adopting the steel bar anchor rod 4 and adding cement to jet the pile-soil connecting beam in a rotary mode is as follows:

B. when the rear row of piles 2 are drilled, a rock drill bit is used for drilling an anchor rod hole and penetrates through the rear row of piles 2;

c: the rotary spraying drilling machine is arranged in a soil section between the tail section of the drill hole and the two piles, soil bodies in corresponding ranges of the anchoring head and the connecting beam section are cut and locked by high-pressure water flow rotary spraying, and high-pressure clean water is used for cutting;

d: after cutting to reach the design size, the jet grouting drilling machine injects cement paste, the drill rod is withdrawn while injecting, the tail part of the jet grouting drilling machine is changed into normal-pressure grouting at the inner section of the hole of the rear row pile 2 during grouting, high-pressure grouting is adopted during grouting at the soil layer section, the rotary grouting pressure value of the cement paste is 25-30 MPa, the high-pressure grouting can expand the soil layer section, so that the cement paste is combined with soil to form cylindrical cement soil with the hole diameter of 300-500 mm, namely an anchor rod anchoring head outside the rear row pile 2 or an inter-pile connecting beam between the front row pile 1 and the rear row pile 2 is formed;

e: the method comprises the following steps that a steel bar anchor rod 4 is driven into a rear row pile 2 from a front row pile 1, the outer end of the steel bar anchor rod 4 is locked on a wale 5 through a nut and a cushion iron plate after the steel bar anchor rod 4 is driven into the rear row pile 2, and positioning steel bars for centering the anchor rod are further arranged at the inner ends of the front row pile 1 and the rear row pile 2;

f: and inserting a grouting pipe from the pre-buried PVC pipe orifice to perform secondary injection of cement slurry, tightly plugging the orifice during secondary grouting, and injecting the cement slurry into the grouting pipe again after waiting for about 5-6 hours so as to ensure that the anchor rod cement connecting beam is compact and reliable.

While the preferred embodiments of the present invention have been illustrated and described, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. A double-row pile supporting method for adding connecting beams in a soil layer is characterized in that: the method comprises the following steps:

step three: drilling;

2. The double-row pile supporting method for adding the connecting beams in the soil layer according to claim 1, which is characterized in that: the concrete processes of drilling, bolting and grouting in the third step and the fourth step are as follows:

3. The double-row pile supporting method for adding the connecting beams in the soil layer according to claim 2 is characterized in that: and in the process D, the anchor rod is driven into the back row of piles and then locked on the waist rail at the outer end of the pipe seam type anchor rod by using the nut and the iron pad plate.

4. The double-row pile supporting method for adding the connecting beams in the soil layer according to claim 2 is characterized in that: and D, during grouting in the process E, mortar or concrete is poured into the hole by a mortar pump, and the guide pipe is drawn out while pouring.

5. The double-row pile supporting method for adding the connecting beams in the soil layer according to claim 1, which is characterized in that: the concrete processes of drilling, bolting and grouting in the third step and the fourth step are as follows:

6. The double-row pile supporting method for adding the connecting beams in the soil layer according to claim 5, which is characterized in that: and D, during grouting in the process D, the tail part of the rotary jet drilling machine is changed into normal-pressure guniting at the inner section of the rear row of pile holes, and high-pressure guniting is adopted during guniting at the soil layer section.

7. The double-row pile supporting method for adding the connecting beams in the soil layer according to claim 5, which is characterized in that: in the process E, the steel bar anchor rod is driven into the rear row pile and then locked on the waist rail by the nut and the iron pad plate at the outer end of the steel bar anchor rod, and the positioning steel bar used for centering the anchor rod is further arranged at the inner ends of the front row pile and the rear row pile.

8. The double-row pile supporting method for adding the connecting beams in the soil layer according to the claim 2 or 3, which is characterized in that: the front row pile and the rear row pile are both provided with a plurality of piles, and the front row piles and the rear row piles are longitudinally aligned one by one along the foundation pit when in construction.

9. The double-row pile supporting method for adding the connecting beams in the soil layer according to the claim 2 or 3, which is characterized in that: the PVC pipe is fixed on the steel reinforcement cage of the front row pile, two ends of the PVC pipe are sealed, the position of the PVC pipe is equal to the distance between the waist beams arranged in the foundation pit along the vertical distance, and the hole opening of the PVC pipe faces the foundation pit.