CN112832278A - Foundation pit, water-resisting structure and construction method thereof - Google Patents
Foundation pit, water-resisting structure and construction method thereof Download PDFInfo
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- CN112832278A CN112832278A CN202011643476.9A CN202011643476A CN112832278A CN 112832278 A CN112832278 A CN 112832278A CN 202011643476 A CN202011643476 A CN 202011643476A CN 112832278 A CN112832278 A CN 112832278A
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D19/00—Keeping dry foundation sites or other areas in the ground
- E02D19/06—Restraining of underground water
- E02D19/12—Restraining of underground water by damming or interrupting the passage of underground water
- E02D19/18—Restraining of underground water by damming or interrupting the passage of underground water by making use of sealing aprons, e.g. diaphragms made from bituminous or clay material
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D15/00—Handling building or like materials for hydraulic engineering or foundations
- E02D15/02—Handling of bulk concrete specially for foundation or hydraulic engineering purposes
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D5/00—Bulkheads, piles, or other structural elements specially adapted to foundation engineering
- E02D5/18—Bulkheads or similar walls made solely of concrete in situ
- E02D5/187—Bulkheads or similar walls made solely of concrete in situ the bulkheads or walls being made continuously, e.g. excavating and constructing bulkheads or walls in the same process, without joints
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D2250/00—Production methods
- E02D2250/003—Injection of material
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Abstract
The invention discloses a foundation pit, a water-resisting structure and a construction method thereof, wherein the construction method of the water-resisting structure is applied to the foundation pit and comprises the following steps: lowering the first grouting pipes into the stratum corresponding to the area to be excavated of the foundation pit, and injecting water-resisting slurry into the stratum through the first grouting pipes so as to form a water-resisting layer at the depth corresponding to the first grouting pipes; lowering a second grouting pipe into the stratum corresponding to the periphery of the area to be excavated; and rotating the second grouting pipes according to a designated direction, and injecting reinforcing slurry into the stratum through the plurality of second grouting pipes, so that the reinforcing slurry is injected to the joint of the connecting wall to form a reinforcing body at the joint. The technical scheme of the invention aims to effectively cut off the confined water layer so that the precipitation in the foundation pit becomes a closed system.
Description
Technical Field
The invention relates to the technical field of foundation pit engineering, in particular to a foundation pit, a water-resisting structure and a construction method thereof.
Background
For areas with abundant underground water, due to the fact that a geological reason that a confined water layer is communicated with a micro confined water layer generally exists, the situation that the confined water layer cannot be separated due to various reasons is considered in the design process of a deep foundation pit support structure, and particularly when a deep foundation pit is located near a building structure which is strict in settlement control, such as a high-speed railway, an overhead interchange and the like, the following problems exist in the excavation process of the foundation pit:
because the pressure-bearing water layer is communicated up and down and the underground diaphragm wall does not effectively block the pressure-bearing water layer, the normal construction method is adopted for the foundation pit to reduce the water, the pressure-bearing water is lost, the ground surface is settled, and the adjacent building is settled, and if the settlement control requirement of the adjacent building is strict, serious consequences can be generated without taking certain measures.
Disclosure of Invention
The invention mainly aims to provide a foundation pit, a waterproof structure and a construction method thereof, aiming at effectively isolating a confined water layer to enable precipitation in the foundation pit to be a closed system.
In order to achieve the purpose, the invention provides a construction method of a waterproof structure, which is applied to a foundation pit, wherein the foundation pit comprises a plurality of connecting walls, and the construction method comprises the following steps:
lowering a plurality of first grouting pipes into a stratum corresponding to a region to be excavated of the foundation pit, and injecting water-resisting slurry into the stratum through the plurality of first grouting pipes so as to form a water-resisting layer at a depth corresponding to the first grouting pipes;
a plurality of second grouting pipes are lowered into the stratum corresponding to the periphery of the area to be excavated; and rotating the second grouting pipes according to a specified direction, and injecting reinforcing slurry into the stratum through the plurality of second grouting pipes, so that the reinforcing slurry is injected to joints among the plurality of connecting walls to form reinforcing bodies in the joints.
Optionally, before the first grouting pipe is lowered, the construction method further includes: drilling a plurality of first drill holes corresponding to the first grouting pipes one by one in the area to be excavated through a drilling machine; wherein, the first drilling hole of the outermost layer is opened according to the following modes: the waterproof slurry injected into the stratum by the first grouting pipe corresponding to the first drilling hole on the outermost layer can permeate into the stratum area corresponding to the connecting wall along the first direction; the first direction and the axial direction of the first grouting pipe are perpendicular to each other.
Optionally, the step of lowering the first grouting pipes into the formation corresponding to the region to be excavated of the foundation pit includes: the time interval of injecting the water-resisting slurry into the two adjacent first grouting pipes is not less than the preset time interval.
Optionally, before the second grouting pipe is arranged below, the construction method further comprises: drilling a plurality of second drill holes corresponding to the second grouting pipes one by one through a drilling machine; wherein the second bore is drilled as follows: the reinforcing slurry may penetrate into joints between the plurality of the continuous walls in the first direction, so that the reinforcing body is integrally connected with the continuous walls.
Optionally, the step of rotating the second grouting pipes in the designated direction and injecting the consolidation slurry into the formation through the plurality of second grouting pipes comprises: and applying axial tension to lift the second grouting pipe to the ground surface at a preset speed, so that the reinforcing grout can penetrate into the joints of the connecting walls.
Optionally, the step of rotating the second grouting pipes in the designated direction and injecting the consolidation slurry into the formation through the plurality of second grouting pipes comprises: and applying axial tension to lift the second grouting pipe to the ground surface at a preset speed, so that the reinforcing grout can penetrate into the connecting wall.
Optionally, during the process of injecting the water-insulating slurry into the stratum through the plurality of first grouting pipes and injecting the reinforcing slurry into the stratum through the plurality of second grouting pipes, the soil in the stratum is sucked out through a suction pump.
Optionally, the head of the first grouting pipe is provided with a first pressure sensor, the first pressure sensor is electrically connected to a first controller, and the step of injecting the water-resisting grout into the formation through the plurality of first grouting pipes comprises: monitoring a first formation pressure via the first pressure sensor, the controller controlling a jet pressure and/or a jet flow rate of the water-blocking slurry based on the first formation pressure.
Optionally, a second pressure sensor is disposed at an end of the second grouting pipe, the second pressure sensor is electrically connected to a second controller, the step of rotating the second grouting pipe in a specified direction and injecting the consolidation grout into the formation through the plurality of second grouting pipes includes: and monitoring formation pressure through the second pressure sensor, and controlling the injection pressure and/or the injection flow of the water-resisting slurry by the second controller based on the second formation pressure.
Optionally, the invention further provides a water-resisting structure, and the water-resisting structure is manufactured by the construction method.
Optionally, the invention further provides a foundation pit, wherein the foundation pit is of the water-resisting structure; and excavating the area to be excavated to form the foundation pit under the condition that the waterproof structure reaches the preset condition.
The technical scheme of the invention is as follows: lowering the first grouting pipes into the stratum corresponding to the area to be excavated of the foundation pit, and injecting water-resisting slurry into the stratum through the first grouting pipes so as to form a water-resisting layer at the depth corresponding to the first grouting pipes; lowering a second grouting pipe into the stratum corresponding to the periphery of the area to be excavated; and rotating the second grouting pipes according to a specified direction, and injecting reinforcing slurry into the stratum through the plurality of second grouting pipes, so that the reinforcing slurry is sprayed to the joints of the plurality of connecting walls to form reinforcing bodies in the joints. According to the technical scheme, a water isolation layer is formed by grouting and used for isolating a pressure-bearing water layer, and then a reinforcing body 200 is formed at a joint of a connecting wall by grouting; therefore, the area to be excavated of the foundation pit forms a closed area to ensure the hydraulic connection between the inside and the outside of the partition pit and avoid the influence of precipitation in the pit on the building outside the station in the excavation process of the foundation pit.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.
Fig. 1 is a schematic view of a preferred embodiment of a construction method of a water-stop structure according to the present invention;
FIG. 2 is a schematic view of the arrangement of the water-resisting structure of the present invention;
FIG. 3 is a partial schematic view of the arrangement of the pilings of the present invention;
FIG. 4 is a schematic diagram of the design of the position relationship of the drilling hole, the grouting pipe and the pile forming body;
FIG. 5 is a partial schematic view at A of FIG. 2;
FIG. 6 is a schematic plan view of the water-stop structure of the present invention;
fig. 7 is a partial arrangement view of a grout pipe of the reinforcement body of the present invention.
The implementation, functional features and advantages of the objects of the present invention will be further described with reference to the accompanying drawings.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that all the directional indicators (such as upper, lower, left, right, front and rear … …) in the embodiment of the present invention are only used to explain the relative position relationship between the components, the motion situation, etc. in a specific posture (as shown in the drawing), and if the specific posture is changed, the directional indicator is changed accordingly.
In the present invention, unless otherwise expressly specified or limited, the terms "connected," "secured," and the like are to be construed broadly, e.g., "secured" may be fixedly connected, releasably connected, or integral; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected through the use of an interconnecting member or members, or they may be interconnected through a network or network, unless expressly specified otherwise. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to specific situations.
In addition, if there is a description of "first", "second", etc. in an embodiment of the present invention, the description of "first", "second", etc. is for descriptive purposes only and is not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In addition, the meaning of "and/or" appearing throughout includes three juxtapositions, exemplified by "A and/or B" including either A or B or both A and B. In addition, technical solutions between various embodiments can be combined with each other, but must be based on the realization of the technical solutions by a person skilled in the art, and when the technical solutions are contradictory or cannot be realized, the technical solutions should be considered to be absent from the combination and not be within the protection scope of the present invention.
When the foundation pit is constructed in the water-rich area, the bearing water layer cannot be effectively separated by the underground supporting structure due to the fact that the bearing water layer is vertically communicated, and therefore the bearing water is lost, the ground surface is settled, and the safety of surrounding buildings and structures is threatened. For example, the stratum in the water-rich area mainly includes miscellaneous fill, silty clay, silty sand and silt sand, and the geological conditions in these areas are poor and are likely to be displaced due to the change of the stratum pressure, and further expressed as surface subsidence.
According to the technical scheme, before the foundation pit is excavated, the water-proof layer 100 is formed by grouting to the stratum and used for separating the pressure-bearing water layer, and the joint of the connecting wall 400a is reinforced to form the reinforcing body 200, so that the area to be excavated of the foundation pit and the non-excavated area are separated by the water-proof layer 100 and the reinforcing body 200, the water loss of the pressure-bearing water layer of the non-excavated area is avoided when the area to be excavated is excavated, and the influence of the precipitation in the pit on the buildings and structures of the non-excavated area in the excavation process of the foundation pit is further avoided.
Specifically, referring to fig. 1, the present invention provides a construction method of a water-proof structure, which is applied to a foundation pit 400. The construction method comprises the following steps:
s100: lowering first grouting pipes into the stratum 300 corresponding to the region to be excavated of the foundation pit 400, and injecting water-resisting slurry into the stratum 300 through the first grouting pipes to form a water-resisting layer 100 at the depth corresponding to the first grouting pipes;
s200: lowering a second grouting pipe into the stratum 300 corresponding to the periphery of the area to be excavated; the second grouting pipes are rotated in a designated direction, and a reinforcing grout is injected into the formation 300 through the second grouting pipes, so that the reinforcing grout is injected to joints of the connecting walls 400a to form the reinforcing body 200 positioned in the joints.
It should be noted that the area to be excavated may be square, circular, triangular or irregular, which is designed by a designer.
It should be noted that the water-resisting slurry and the reinforcing slurry may be ordinary portland cement (e.g. p.o42.5 grade ordinary portland cement), and the water cement ratio of the cement slurry is 1: 1, specific gravity of 1.51; the manufacturing process of the waterproof slurry and the reinforced slurry at least needs to meet the following requirements: the rotating speed and the mixing capacity of the mixer are respectively adapted to the type of the slurry to be mixed and the slurry discharge amount of the grouting pump, and the uniform and continuous mixing of the slurry can be ensured. Ensuring the continuous slurry supply demand of high-pressure jet grouting. Before the slurry is used, the slurry conveying pipeline and the pressure gauge are checked to ensure that the slurry is smoothly sprayed into the stratum through the slurry conveying pipeline.
It should be noted that the corresponding depth and the specified direction are determined by combining the engineering practice. The corresponding depth is mainly based on the excavation depth of the foundation pit, and the grouting depth of the invention can reach 43m at most, namely the water-resisting layer 100 of the invention can be positioned at 43m underground (the distance from the deepest part of the water-resisting layer 100 to the ground). Rotating the second grouting pipe in a specified direction is required to enable the reinforcing slurry injected through the second grouting pipe to penetrate into the joint in a certain direction; on one hand, a part of the reinforcing body 200 is a pile body and is also positioned outside the connecting wall, which is beneficial to reinforcing the outer wall 400a and improving the bending resistance of the outer wall 400 a; on the other hand, when the foundation pit is excavated, the reinforcing body 200 prevents water in the pressure-bearing water layer from flowing into the pit through the joint. For example, the designated direction is swinging 180 degrees, and the spraying direction is towards the area to be excavated of the foundation pit.
It should be noted that the grouting process of the present invention may be an MJS (all-around high-pressure injection) construction process.
According to the technical scheme, a water-resisting layer 100 is formed by grouting and used for blocking a pressure-bearing water layer, and then a reinforcing body 200 is formed at a joint of a connecting wall 400a by grouting; therefore, the area to be excavated of the foundation pit forms a closed area to ensure the hydraulic connection between the inside and the outside of the partition pit and avoid the influence of precipitation in the pit on the building outside the station in the excavation process of the foundation pit.
Optionally, the foundation pit 400 includes a connecting wall 400 a. The continuous wall 400a, i.e., the continuous wall, also called underground continuous wall, is a foundation engineering, and a long and narrow deep groove is dug on the ground along the peripheral axis of the deep excavation engineering under the condition of slurry wall protection. After the groove is cleaned, a reinforcement cage is hoisted in the groove, and then underwater concrete is poured by a guide pipe method to form a unit groove section. The construction is carried out section by section, and a continuous reinforced concrete wall is built underground and serves as a water interception, seepage prevention, bearing and water retaining structure. The construction of the connecting wall 400a should be performed before the construction of the waterproof structure for preliminary support of the foundation pit 400. Before the first slip casting pipe is lowered down,
the construction method further comprises the following steps: drilling a plurality of first drill holes corresponding to the first grouting pipes one by one in the area to be excavated through a drilling machine; in the invention, the process of drilling the first drill hole by the drilling machine at least comprises the following steps:
the drill is in place. The main drill rod of the drilling machine is aligned with the hole position, the horizontal ruler is used for measuring the horizontal direction of the machine body, the vertical shaft is vertical, and the drilling machine needs to be stably and firmly padded.
The bore diameter of the drill hole is larger than the outer diameters of the first grouting pipe and the second grouting pipe of the first grouting pipe by 100-200 mm, and the diameter of the selected pilot hole is not larger than 300 mm.
If the survey data of the construction site is unknown, pilot holes are arranged at intervals of 20m, and stratum change of final holes is checked.
And measuring the horizontal position of the machine body and the vertical position of the vertical shaft for 1 time by using a horizontal ruler every 5m of drilled holes so as to ensure that the drilled holes are vertical.
During drilling, stratum changes are noticed at any time, and the conditions of hole depth, hole collapse, slurry leakage and the like need to be recorded in detail.
The final hole depth of the drilled hole is 0.5-1.0 m greater than the opening spraying depth so as to meet the requirements of small amount of precipitation and the distance between the front ends of the nozzles. After finishing the hole, the residue in the hole is fished and replaced clean.
And in the drilling process, attention is paid to the detection of the perpendicularity of the hole, and the station position of the hole guiding equipment is timely adjusted when abnormality is found.
And (3) measuring the hole depth: and measuring the length of a drill rod and a drilling tool when drilling a final hole, and ensuring that the depth of the pilot hole meets the requirement.
The first drilling hole in the outermost layer is formed in the following mode: the water-resisting grout injected into the stratum 300 by the first grouting pipe corresponding to the first drilling hole on the outermost layer can penetrate into the stratum 300 area corresponding to the connecting wall 400a along the first direction; the first direction and the axial direction of the first grouting pipe are perpendicular to each other. Referring to fig. 3, namely: the pile-forming body corresponding to the first grouting pipe on the outermost layer has a projection on the cross section of the connecting wall 400a, and the first direction is transverse (if the foundation pit is circular, the first direction is the radial direction of the foundation pit). Referring to fig. 3, the radius of the pilings corresponding to the outermost first grouting pipe is R0, the center of mass of the pilings is L0 from the wall 400a, and the radius of the pilings R0 needs to be greater than L0. For example, R is 1200mm and L is 700 mm.
Referring to fig. 3, two adjacent pile forming bodies are connected to each other, so that the formed water-stop layer 100 is connected into a whole.
Referring to FIG. 4, the diameter of the first bore is set to D1The diameter of the first grouting pipe is D2. Under the general conditions, D2Is less than D 1100 mm-200 m. The diameter of the pile body is D3Greater than D1(ii) a Typically, the pile-forming body has a diameter D3And determining by combining geological conditions, the pipe diameter of the first grouting pipe, the injection flow and the injection pressure.
In general, the thickness of the water-barrier layer 100 is also determined according to geological conditions and the distance from a nearby structure. The worse the geological conditions, the greater the thickness of the water barrier 100; the smaller the distance from a nearby structure, the greater the thickness of the water barrier 100.
Optionally, the step of lowering the first grouting pipes into the formation 300 corresponding to the region to be excavated of the foundation pit 400, and the step of injecting the water-proof slurry into the formation 300 through the first grouting pipes includes: injecting water-proof slurry into the stratum 300 through the first grouting pipe according to a pile jumping mode; and the time interval of injecting the water-resisting slurry into the two adjacent first grouting pipes is less than the preset time interval. The pile jumping mode can be as follows: numbering the first drill holes in sequence, and injecting the water-resisting slurry into the stratum 300 through a first grouting pipe corresponding to the base number; then injecting the water-resisting slurry into the stratum 300 by using the first grouting pipes corresponding to the even numbers; and the injection time interval of two adjacent first grouting pipes is not less than the preset time interval. Typically, the predetermined time interval is 24 hours. Without being limited to the above, if the grouting cannot meet the requirement of pile jump construction, it should be ensured that the time interval for injecting the water-resisting slurry into the two adjacent first grouting pipes of the same longitudinal section should be not less than the preset time interval. Typically, the predetermined time interval is 24 hours. Namely: the grouting time of two adjacent hole sites is not less than the preset time interval, so that two adjacent holes are prevented from being serially grouted and mutually influenced, and the forming quality of the waterproof layer is improved.
Optionally, before the second grouting pipe is arranged below, the construction method further comprises: drilling a plurality of second drill holes corresponding to the second grouting pipes one by one through a drilling machine; wherein the second bore is drilled as follows: the reinforcing grout may penetrate into the region of the ground layer 300 corresponding to the connecting wall 400a in the first direction, so that the reinforcing body 200 is integrally connected with the waterproof layer 100; and/or the reinforcing grout may penetrate into the joints of the connecting wall 400a in the first direction to integrate the reinforcing body 200 with the connecting wall 400 a. The construction mode of the second drilling hole is consistent with that of the first drilling hole. The difference is only that the hole-forming diameter of the second bore is smaller than the hole-forming diameter of the first bore. The pile-forming body corresponding to the reinforcing body 200 is also smaller than the pile-forming body corresponding to the water-resisting layer 100. Referring to fig. 3, if the radius of the pile body corresponding to the reinforcing structure 200 is R1 and the distance from the center of the pile body to the partition wall is L1, R1 is greater than L1, that is, the pile body corresponding to the reinforcing structure 200 penetrates into the connecting wall 400a to be connected therewith. Referring to fig. 7, the grout holes 200a (actually circular, illustrating the direction of injection of the grout pipe: injection in a semicircle) are located outside the seam connecting the walls 400 a.
Preferably, in the invention, after the drilled hole is qualified, the high-pressure jet grouting can be performed, and the following items are checked before the first grouting pipe and the second grouting pipe are arranged:
(1) and measuring the lengths of the first grouting pipe and the second grouting pipe, and measuring whether the central line of the nozzle is consistent with the directions of the first grouting pipe and the second grouting pipe, wherein the first grouting pipe and the second grouting pipe are required to mark the scale.
(2) And (3) placing the spray head near a high-pressure water pump, wherein the pressure test pipeline is less than 20m, and the pilot spraying is adjusted to the designed spraying pressure.
(3) During construction, the ground gas and slurry trial spraying is carried out before the first grouting pipe and the second grouting pipe, namely the spraying pressure and the pipeline pressure are designed.
(4) And designing the injection pressure and the pipeline pressure as the standard injection pressure for construction, and debugging when the nozzle is replaced.
(5) And in the swing spraying construction, before the first grouting pipe and the second grouting pipe, performing ground trial spraying and adjusting the spraying direction and the swing angle.
(6) In the process of the lower first grouting pipe and the second grouting pipe, in order to prevent the nozzle from being blocked by the sand, water injection and pipe insertion can be carried out at the same time, the water pressure is generally not more than 1MPa, and if the pressure is too high, the hole wall is easy to collapse.
Alternatively, in the present invention, the MJS high-pressure jet grouting method is a bottom-up continuous operation.
(1) When the first grouting pipe and the second pipe reach the designed depth, the nozzle reaches the designed elevation, and then grouting can be injected.
(2) And (5) construction is carried out strictly according to the MJS construction parameters.
In the present invention, one preferable construction process parameter in the process of injecting the grout through the first grout pipe and the second grout pipe is:
(3) the sudden pressure drop or increase occurs during the injection process, and the cause must be found and dealt with in time.
(4) When the jet pipe is disassembled in the jetting process, the drop lapping re-jetting is carried out, and the lapping length is not less than 0.2 m.
(5) After interruption of the spraying process due to reasons, re-spraying is carried out when the spraying is resumed, and the lap joint length is not less than 0.5 m.
(6) And (3) when the jet interruption exceeds the initial setting time of the slurry, hole sweeping is carried out, and when jet is recovered, the overlap length of the re-jet is not less than 1 m.
(7) And (4) stopping lifting until slurry does not leak in the hole in the spraying process, and continuing lifting.
(8) And stopping spraying when slurry in the hole seriously leaks in the spraying process, and taking a leakage stopping measure by lifting the spraying pipe.
After the MJS high-pressure injection grouting of each hole is completed, a grouting pump and a slurry conveying pipeline are cleaned in time, and the phenomenon that slurry is deposited and caked in the slurry conveying pipeline due to untimely and incomplete cleaning, the slurry conveying pipeline and a nozzle are blocked, and the construction of the next hole is influenced is prevented.
After each hole drilling rod is taken out, yellow sand or subsequent slurry return is adopted for backfilling the drilling hole in time to avoid ground settlement caused by hole collapse.
Optionally, the step of rotating the second grouting pipes in the designated direction and injecting the consolidation slurry into the formation 300 through the plurality of second grouting pipes comprises: the second grout pipe is lifted to the surface at a predetermined speed in the axial direction of the second grout pipe so that the reinforcing grout can penetrate into the joint of the continuous wall 400 a. Referring to fig. 2, the reinforcing body 200 has an extension in the axial direction of the foundation pit, and a specific extension height thereof is determined according to actual geological conditions to ensure the interruption of the confined water layer. To this end, the second grout pipe is lifted to the surface at a predetermined speed in the axial direction of the second grout pipe so that the reinforcing grout can penetrate into the connecting wall 400a to extend in the axial direction. The speed of the lifting is not easy to be overlarge, and is generally between 1.5cm and 2.5cm per minute, and 2cm is preferred. If the thickness of water-resisting layer is great, also can be through applying axial tension to first slip casting pipe for first slip casting pipe sprays on different heights, with the thickness requirement that satisfies the water-resisting layer.
Optionally, during the process of injecting the water-proof slurry into the formation 300 through the plurality of first grouting pipes and injecting the reinforcing slurry into the formation 300 through the plurality of second grouting pipes, the soil in the formation 300 is sucked out through a suction pump. The pumping soil mainly forms a water-resisting slurry or an annular channel for reinforcing the slurry in the stratum, so that a water-resisting layer or a reinforcing body is formed conveniently. In the specific implementation process, the suction pump is located on the ground, the first grouting pipe and the second grouting pipe are provided with suction channels, and the suction pump sucks soil out through the suction channels.
In the process of sucking out soil, the formation pressure is disturbed, so that the formation pressure needs to be monitored, on one hand, the borehole is prevented from collapsing, and on the other hand, the influence of excessive disturbance of the formation pressure on the quality of a water-resisting layer or a reinforcing body is reduced. For this purpose,
optionally, the head of the first grouting pipe is provided with a first pressure sensor electrically connected to a first controller, and the step of injecting the water-insulating slurry into the formation 300 through the first grouting pipes comprises: monitoring a first formation 300 pressure via the first pressure sensor, the controller controlling a jetting pressure and/or a jetting flow rate of the water-blocking slurry based on the first formation 300 pressure.
Optionally, the end of the second grouting pipe is provided with a second pressure sensor, the second pressure sensor is electrically connected to a second controller, and the step of rotating the second grouting pipe in a specified direction and injecting the reinforcing grout into the formation 300 through the plurality of second grouting pipes comprises: monitoring formation 300 pressure via the second pressure sensor, the second controller controlling injection pressure and/or injection flow of the water-blocking slurry based on the second formation 300 pressure.
According to the technical scheme, when the stratum is grouted through the first grouting pipe and the second grouting pipe, the pressure of the stratum is measured through the first pressure sensor and the pressure of the stratum is measured through the second pressure sensor respectively, and the underground pressure is strictly controlled. For example, when the formation pressure measured by the first pressure sensor is high, the oil pressure joint can be controlled by the controller to increase the opening size of the slurry suction hole, so that the slurry discharge amount is increased to reach a range of a pressure value in a control soil body or the jet flow is reduced to reduce the formation pressure. Correspondingly, when the formation pressure measured by the first pressure sensor is lower, the oil pressure joint can be controlled by the controller to reduce the opening size of the slurry suction hole so as to reduce the slurry discharge amount to reach the range of the pressure value in the soil body or increase the injection flow rate to increase the pressure in the ground. The method greatly reduces the influence on the environment, avoids the soil compaction effect, and greatly reduces the conditions of surface deformation, building cracking, structure displacement and the like in the construction. Meanwhile, the reasonable control of the pressure in the bottom is beneficial to the permeation of the water-resisting slurry and the reinforcing slurry in the stratum, so that the formation quality of the water-resisting layer and the reinforcing body is ensured, and the separation of the pressure-bearing water layer is facilitated.
Optionally, the invention further provides a water-resisting structure, and the water-resisting structure is manufactured by the construction method.
Optionally, the present invention further provides a foundation pit 400, where the foundation pit 400 includes the aforementioned water-insulating structure; and excavating the area to be excavated to form the foundation pit 400 under the condition that the waterproof structure reaches the preset condition. The preset conditions are as follows: after the construction is finished, the strength of the pile body of the MJS construction method is checked by adopting a drilling coring sampling test. The influence of coring on the reinforcing body is considered, so that the detection aim is ensured, and measures are convenient to take without sequela caused by drilling. During coring, a through hole is not formed, so that the overall effect of the MJS water-resisting layer is ensured as much as possible. The number of the drilling and coring check points is 2 percent of the number of the construction piles, and the unconfined compressive strength reaches more than 1.5MPa after 28 days. Pit 400 also includes a bottom support structure 400b, which is formed after the pit is excavated. The water barrier 100 is located within the formation 300 on the underside of the bottom support structure 400 b.
The above description is only an alternative embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications and equivalents made by the contents of the present specification and drawings, or directly/indirectly applied to other related technical fields, are included in the scope of the present invention.
Claims (10)
1. A construction method of a waterproof structure is applied to a foundation pit, wherein the foundation pit comprises a plurality of connecting walls, and the construction method is characterized by comprising the following steps:
lowering a plurality of first grouting pipes into the stratum corresponding to the area to be excavated of the foundation pit, and injecting water-resisting slurry into the stratum through the plurality of first grouting pipes so as to form a water-resisting layer at the depth corresponding to the first grouting pipes;
a plurality of second grouting pipes are lowered into the stratum corresponding to the periphery of the area to be excavated; and rotating the second grouting pipes according to a specified direction, and injecting reinforcing slurry into the stratum through the plurality of second grouting pipes, so that the reinforcing slurry is injected to joints among the plurality of connecting walls to form reinforcing bodies in the joints.
2. The construction method according to claim 1,
before the first grouting pipe is laid down, the construction method further includes:
drilling a plurality of first drill holes corresponding to the first grouting pipes one by one in the area to be excavated through a drilling machine;
the first drilling hole in the outermost layer is formed in the following mode: the waterproof slurry injected into the stratum by the first grouting pipe corresponding to the first drilling hole on the outermost layer can permeate into the stratum area corresponding to the connecting wall along the first direction; the first direction and the axial direction of the first grouting pipe are perpendicular to each other.
3. The construction method according to claim 2, wherein the first grouting pipes are lowered into the formation corresponding to the region to be excavated of the foundation pit, and the step of injecting the water-blocking slurry into the formation through the plurality of first grouting pipes comprises:
the time interval of injecting the water-resisting slurry into the two adjacent first grouting pipes is not less than the preset time interval.
4. The construction method according to claim 2, wherein before the second grout pipe is located therebelow, the construction method further comprises:
drilling a plurality of second drill holes corresponding to the second grouting pipes one by one through a drilling machine;
wherein the second bore is drilled as follows: the reinforcing slurry may penetrate into joints between the plurality of the continuous walls in the first direction, so that the reinforcing body is integrally connected with the continuous walls.
5. The method of claim 4, wherein the step of rotating the second grout pipes in the designated direction and injecting the reinforcing grout into the formation through the plurality of second grout pipes comprises:
and applying axial tension to lift the second grouting pipe to the ground surface at a preset speed, so that the reinforcing grout can penetrate into the joints of the connecting walls.
6. The construction method according to any one of claims 1 to 5, wherein during the injecting of the water-barrier slurry into the formation through the plurality of first grout pipes and the injecting of the reinforcing slurry into the formation through the plurality of second grout pipes,
and sucking out soil in the stratum by a suction pump.
7. The construction method according to any one of claims 1 to 5, wherein a tip of the first grout pipe is provided with a first pressure sensor electrically connected to a first controller,
the step of injecting water-insulating slurry into the stratum through the plurality of first grouting pipes comprises the following steps:
monitoring a first formation pressure by the first pressure sensor, the controller controlling a jetting pressure and/or a jetting flow rate of the water-blocking slurry based on the first formation pressure.
8. The construction method according to claim 7, wherein the tip of the second grouting pipe is provided with a second pressure sensor electrically connected to a second controller,
the steps of rotating the second grouting pipes according to the designated direction and injecting the reinforcing slurry into the stratum through the second grouting pipes comprise:
and monitoring the formation pressure through the second pressure sensor, and controlling the injection pressure and/or the injection flow of the water-resisting slurry by the second controller based on the second formation pressure.
9. A water-barrier structure, characterized in that it is made by the construction method according to any one of claims 1 to 8.
10. A foundation pit, characterized in that it comprises the water-barrier structure of claim 9; and excavating the area to be excavated to form the foundation pit under the condition that the waterproof structure reaches the preset condition.
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