Construction method of foundation pit support
阅读说明:本技术 一种基坑支护的施工方法 (Construction method of foundation pit support ) 是由 修岩 冯旭 左军锋 于 2020-05-25 设计创作,主要内容包括:本申请涉及一种基坑支护的施工方法,包括钢管桩施工和利用灌浆管进行灌浆施工两个步骤,灌浆管内安装双环栓塞管,双环栓塞管上下的封隔器可实现分段分层灌浆,可根据施工需要选择连续或者间隔灌浆,能够重复灌浆,还可以根据各个区域不同的地质水文条件特性而选择不同的灌浆参数和灌浆材料,从而使得松散的地层和较密实的地层均得到很好的灌浆加固效果。采用本申请的施工方法,其支护强度高、防渗能力强,能够适用于各种复杂的地质条件。(The utility model relates to a construction method of foundation ditch support, including steel-pipe pile construction and utilize the grout pipe to carry out two steps of grout construction, install dicyclo embolism pipe in the grout pipe, packer about the dicyclo embolism pipe can realize the segmentation layering grout, can select continuous or interval grout according to the construction needs, can repeat the grout, can also select different grouting parameters and grouting material according to the different geology hydrology condition characteristics in each region, thereby make loose stratum and more closely knit stratum all obtain fine grout reinforcement effect. By adopting the construction method, the support strength is high, the seepage-proofing capability is strong, and the method can be suitable for various complicated geological conditions.)
1. A construction method of foundation pit support comprises two steps of steel pipe pile construction and grouting construction by using grouting pipes, wherein the steel pipe piles and the grouting pipes are arranged at intervals respectively, and the steel pipe piles and the grouting pipes in adjacent rows are arranged in a staggered mode, and the construction method is characterized by comprising the following steps:
(1.1) establishing the position of the pile, removing the obstacle, drawing the position of the pile on the ground and checking and verifying;
(1.2) trial punching is carried out before formal piling so as to test the noise and vibration values of the pile driver during working; drilling a hole in the established pile position to the rock stratum;
(1.3) blowing the earth and rock ballast at the ground into the steel sleeve in the drilling process, and judging whether to drill to the rock surface of the bearing stratum or not by checking the earth and rock ballast; when the hole is drilled to the depth of the rock surface of the preset bearing stratum, taking out a rock ballast sample, and judging whether the corresponding drilling depth reaches the design standard or not;
(1.4) after the drilling machine continues to drill to the rock-entering depth required by the design, collecting the blown-out rock ballast sample again, and checking and accepting to judge whether the rock-entering depth meets the design standard;
(1.5) after the rock stratum meets the acceptance requirements, injecting clear water into the pile hole, and removing sand and stones in the hole by using a high-pressure fan, wherein the hole clearing time is not less than 15 minutes; taking out a water sample for inspection and acceptance, and judging that the cleaned holes are clean if no sand sediment exists in the water sample; after the drilling quality is verified again to meet the design requirement, the drilling process is finished;
(1.6) measuring the elevation of the top surface of the steel sleeve, calculating the elevation of the pile bottom according to the measured drilling depth, and measuring the eccentricity and the verticality of the drilled hole;
(1.7) putting the steel pipe pile of the enclosure structure, and carrying out layered sand filling work after the steel pipe pile reaches the design depth to ensure that the filled sand body is compact;
the grouting construction by using the grouting pipe comprises the following steps:
(2.1) temporary steel sleeves are drilled along with the steel sleeves in the drilling process to prevent hole collapse;
(2.2) drilling from the ground to the position below the rock surface, and installing a grouting pipe; the grouting pipes are provided with leakage holes at intervals and are connected by a rubber sleeve;
(2.3) pouring dilute cement slurry into the gap between the grouting pipe and the steel sleeve to form an outer skin slurry protection grouting pipe, wherein the dilute cement slurry comprises bentonite, cement and water in a weight ratio of 1:8-12: 18-22;
(2.4) after the installation and grouting are finished, drawing away the temporary steel sleeve to ensure that the hole wall and the grouting pipe are protected by dilute cement slurry;
(2.5) after the dilute cement slurry protective layer is solidified, installing a double-ring plug pipe in the grouting pipe, and performing first-stage grouting; grouting pressure reaches more than 2-3 bar in the first stage or grouting amount reaches 500 liters per meter, and grouting is stopped on the basis of higher grouting pressure; the slurry for the first stage grouting comprises bentonite, cement and water according to the mass ratio of 1 (8-12): (23-26) in proportion;
(2.6) performing second-stage grouting at intervals of at least 18 hours after the first-stage grouting; the slurry for the second stage grouting comprises a first reagent and a second reagent, wherein the first reagent is formed by mixing sodium silicate and water according to the mass ratio of 1 (1.4-1.8), and the second reagent is formed by mixing cement and water according to the mass ratio of 1 (4-6);
(2.7) the grouting process is carried out from the bottom, and the grouting process is moved upwards to the existing ground after each section is finished; and drilling and coring are carried out after grouting is finished, a sample is extracted for carrying out a compression resistance test, and the next procedure is carried out after the test result meets the design requirement.
2. The construction method according to claim 1, wherein the diameter of the drill hole drilled by the exploratory drill is 80 mm; the diameter of the grouting pipe is 48mm, the length of the grouting pipe is 4 meters, and the bottommost part and the topmost part of the grouting pipe are provided with sealing covers.
3. The construction method according to claim 1, wherein the grouting pipe is a PVC grouting pipe, and the PVC grouting pipe and the rubber sleeve are bonded by quick-drying glue.
4. The construction method according to any one of claims 1 to 3, wherein the double-ring plug pipe comprises pressurizing packers at the upper end and the lower end, connecting sections are arranged at both ends of each pressurizing packer, a grouting section is arranged between the opposite connecting sections of the two pressurizing packers, an inlet end of the upper pressurizing packer is connected with an injection pipe and a hose, the injection pipe is connected with an external grouting system, and the hose is connected with external pressurizing equipment; pressurization can make the pressurization packer inflation at both ends through pressure equipment to in the hose to sealed with the both ends of double ring plug pipe, through the grout pipe of the thick liquid of filling tube injection grout section through the slip casting mouth injection grout pipe in, the slip casting mouth sets up the bottom at last pressurization packer.
5. The construction method according to claim 4, wherein the injection pipe is connected with a grouting pump, a flowmeter and a pressure gauge in sequence during the first stage grouting; when the grout is in the second stage, the upper reaches of the injection pipe are divided into a first branch and a second branch, the first branch and the second branch are respectively used for injecting a first reagent and a second reagent, and the first branch and the second branch are respectively and sequentially connected with a grouting pump, a flowmeter, a pressure gauge and a switch valve.
6. The construction method according to any one of claims 1 to 5, wherein the grout for the first stage is 35 kg of bentonite, 350 kg of cement and 870 kg of water per cubic meter of the formulation, and the grout for the second stage is 208 kg of sodium silicate, 339 kg of water in the first agent, 94 kg of cement and 472 kg of water in the second agent per cubic meter of the formulation.
Technical Field
The application relates to a construction method of a foundation pit support, which is suitable for the technical field of foundation pit support.
Background
At present, in deep foundation pit supporting in coastal areas, steel pipe piles, particularly 508 steel pipe piles, are often adopted as supporting soil retaining structures, and the steel pipe supporting piles are easy to leak in the process of foundation pit excavation, so that great influence is caused on the safety of the foundation pit. When the foundation pit leakage is retreated, the construction difficulty is high, and the original supporting structure is easy to damage.
Therefore, how to develop a construction method of a waterproof curtain with high supporting strength and strong seepage-proofing capability is a technical problem to be solved urgently in the field.
Disclosure of Invention
The invention aims to design a construction method for a foundation pit support, which has high support strength and strong seepage-proofing capability and can be suitable for various complicated geological conditions.
The construction method of foundation pit support according to the application comprises two steps of steel pipe pile construction and grouting construction by using grouting pipes, wherein the steel pipe piles and the grouting pipes are arranged at intervals, and the steel pipe piles and the grouting pipes in adjacent rows are arranged in a staggered mode, and the steel pipe pile construction comprises the following steps:
(1.1) establishing the position of the pile, removing the obstacle, drawing the position of the pile on the ground and checking and verifying;
(1.2) trial punching is carried out before formal piling so as to test the noise and vibration values of the pile driver during working; drilling a hole in the established pile position to the rock stratum;
(1.3) blowing the earth and rock ballast at the ground into the steel sleeve in the drilling process, and judging whether to drill to the rock surface of the bearing stratum or not by checking the earth and rock ballast; when the hole is drilled to the depth of the rock surface of the preset bearing stratum, taking out a rock ballast sample, and judging whether the corresponding drilling depth reaches the design standard or not;
(1.4) after the drilling machine continues to drill to the rock-entering depth required by the design, collecting the blown-out rock ballast sample again, and checking and accepting to judge whether the rock-entering depth meets the design standard;
(1.5) after the rock stratum meets the acceptance requirements, injecting clear water into the pile hole, and removing sand and stones in the hole by using a high-pressure fan, wherein the hole clearing time is not less than 15 minutes; taking out a water sample for inspection and acceptance, and judging that the cleaned holes are clean if no sand sediment exists in the water sample; after the drilling quality is verified again to meet the design requirement, the drilling process is finished;
(1.6) measuring the elevation of the top surface of the steel sleeve, calculating the elevation of the pile bottom according to the measured drilling depth, and measuring the eccentricity and the verticality of the drilled hole;
(1.7) putting the steel pipe pile of the enclosure structure, and carrying out layered sand filling work after the steel pipe pile reaches the design depth to ensure that the filled sand body is compact;
the grouting construction by using the grouting pipe comprises the following steps:
(2.1) temporary steel sleeves are drilled along with the steel sleeves in the drilling process to prevent hole collapse;
(2.2) drilling from the ground to the position below the rock surface, and installing a grouting pipe; the grouting pipes are provided with leakage holes at intervals and are connected by a rubber sleeve;
(2.3) pouring dilute cement slurry into the gap between the grouting pipe and the steel sleeve to form an outer skin slurry protection grouting pipe, wherein the dilute cement slurry comprises bentonite, cement and water in a weight ratio of 1:8-12: 18-22;
(2.4) after the installation and grouting are finished, drawing away the temporary steel sleeve to ensure that the hole wall and the grouting pipe are protected by dilute cement slurry;
(2.5) after the dilute cement slurry protective layer is solidified, installing a double-ring plug pipe in the grouting pipe, and performing first-stage grouting; grouting pressure reaches more than 2-3 bar in the first stage or grouting amount reaches 500 liters per meter, and grouting is stopped on the basis of higher grouting pressure; the slurry for the first stage grouting comprises bentonite, cement and water according to the mass ratio of 1 (8-12): (23-26) in proportion;
(2.6) performing second-stage grouting at intervals of at least 18 hours after the first-stage grouting; the slurry for the second stage grouting comprises a first reagent and a second reagent, wherein the first reagent is formed by mixing sodium silicate and water according to the mass ratio of 1 (1.4-1.8), and the second reagent is formed by mixing cement and water according to the mass ratio of 1 (4-6);
(2.7) the grouting process is carried out from the bottom, and the grouting process is moved upwards to the existing ground after each section is finished; and drilling and coring are carried out after grouting is finished, a sample is extracted for carrying out a compression resistance test, and the next procedure is carried out after the test result meets the design requirement.
Wherein the diameter of the drill hole of the exploration drilling machine is 80 mm; the diameter of the grouting pipe is 48mm, the length of the grouting pipe is 4 meters, and the bottommost part and the topmost part of the grouting pipe are provided with sealing covers; the grouting pipe is a PVC grouting pipe, and the PVC grouting pipe and the rubber sleeve are bonded by quick-drying glue.
The double-ring plug pipe comprises pressurizing packers positioned at the upper end and the lower end, two ends of each pressurizing packer are respectively provided with a connecting section, a grouting section is arranged between the two opposite connecting sections of the pressurizing packers, the inlet end of the upper pressurizing packer is connected with an injection pipe and a hose, the injection pipe is connected with an external grouting system, and the hose is connected with external pressurizing equipment; pressurization can make the pressurization packer inflation at both ends through pressure equipment to in the hose to sealed with the both ends of double ring plug pipe, through the grout pipe of the thick liquid of filling tube injection grout section through the slip casting mouth injection grout pipe in, the slip casting mouth sets up the bottom at last pressurization packer.
Wherein, during the first stage of grouting, the injection pipe is sequentially connected with a grouting pump, a flowmeter and a pressure gauge; when the grout is in the second stage, the upper reaches of the injection pipe are divided into a first branch and a second branch, the first branch and the second branch are respectively used for injecting a first reagent and a second reagent, and the first branch and the second branch are respectively and sequentially connected with a grouting pump, a flowmeter, a pressure gauge and a switch valve. The first stage grouting slurry is 35 kg of bentonite, 350 kg of cement and 870 kg of water per cubic meter of the ingredient, and the second stage grouting slurry is 208 kg of sodium silicate, 339 kg of water in the first agent, 94 kg of cement and 472 kg of water in the second agent per cubic meter of the ingredient.
The construction method of the foundation pit support can realize the segmented layered grouting, can select continuous or interval grouting according to construction requirements, can repeatedly perform grouting at any section in a grouting area, can adopt different grouting materials in the same grouting pipe, select different grouting pressures and the like, has the remarkable advantages of safe and reliable construction technology, and can ensure that both loose strata and more compact strata can obtain good grouting reinforcement effect;
drawings
Fig. 1 shows a schematic view after a temporary steel casing is put in a grouting construction step.
Fig. 2 shows a schematic view of the grout pipe installed in the grouting construction step.
Fig. 3 shows a schematic view after the temporary steel casing is withdrawn in the grouting construction step.
Fig. 4 shows a schematic view of a first stage grouting by installing a double ring plug pipe in a grouting construction step.
Fig. 5 is a schematic view showing a second stage grouting by installing a double ring plug pipe in a grouting construction step.
Fig. 6 shows a schematic view of a double ring plug tube used in the grout pipe of the present application.
Fig. 7 is a plan view schematically showing a space enclosing structure of a steel pipe pile region formed after completion of a grouting curtain construction work.
Detailed Description
To make the objects, technical solutions and advantages of the present application more apparent, embodiments of the present application will be described in detail below with reference to the accompanying drawings. It should be noted that the embodiments and features of the embodiments in the present application may be arbitrarily combined with each other without conflict.
The construction method of the foundation pit support comprises two steps of steel pipe pile construction and grouting construction by using a grouting pipe, wherein the steel pipe pile construction comprises the following steps:
(1.1) establishing the position of the pile, removing the obstacle and removing it, drawing the position of the pile on the ground and checking and verifying that the error is not more than 75 mm.
(1.2) trial punching is carried out before formal piling so as to test the noise and vibration values of the pile driver during working; drilling holes to the rock formation at the established pile locations. For example, an ODEX system (i.e. an eccentric bit following pipe drilling system) drilling machine and a 508 steel sleeve drilling method can be adopted, a pneumatic hammer is used for cleaning the soft soil on the top layer in the steel sleeve and a strip steel sleeve synchronously drills into the ground bottom to a rock stratum, sewage generated in the drilling process is discharged to a specified place after three-stage sedimentation, and when the drilling depth exceeds the standard length of the 508 steel pipe, the welding mode is adopted for connection.
(1.3) blowing the earth and rock ballast at the ground into the steel sleeve in the drilling process, and judging whether to drill to the rock surface of the bearing stratum or not by checking the earth and rock ballast; when the hole is drilled to the depth of the rock surface of the preset bearing stratum, taking out an earth and rock slag sample, and judging whether the corresponding drilling depth reaches the design standard or not;
(1.4) after the drilling machine continues to drill to the rock-entering depth required by the design, collecting the blown-out rock ballast sample again, and checking and accepting to judge whether the rock-entering depth meets the design standard;
(1.5) after the rock stratum meets the acceptance requirements, injecting clear water into the pile hole, and removing sand and stones in the hole by using a high-pressure fan, wherein the time for cleaning the hole is not less than 15 minutes. Taking out a water sample for inspection and acceptance, and judging that the cleaned holes are clean if no sand sediment exists in the water sample; after the drilling quality is verified again to meet the design requirement, the drilling process is finished;
(1.6) measuring the elevation of the top surface of the steel sleeve, calculating the elevation of the pile bottom according to the measured drilling depth, and measuring the eccentricity and the verticality of the drilled hole;
and (1.7) putting the steel pipe pile of the enclosure structure, and carrying out layered sand filling work after the steel pipe pile reaches the design depth to ensure that the filled sand body is compact.
Referring to fig. 1-5, steps of grouting construction using a grout pipe are shown. The application discloses utilize grout pipe to carry out grouting construction, including following step:
(2.1) as shown in figure 1, the diameter of a drill hole of the exploration drilling machine is 80mm, the
And (2.2) drilling from the ground to the depth of 1m below the rock surface, and installing a grouting pipe 2 with the diameter of 48 mm. As shown in figure 2, the grouting pipes 2 are provided with
(2.3) pouring dilute cement slurry into the gap between the grout pipe 2 and the
(2.4) after the installation and grouting are finished, the
(2.5) after the protective layer of the
As shown in fig. 4, in the first stage grouting, a
And (2.6) performing second-stage grouting at intervals of at least 18 hours after the first-stage grouting. The slurry for the second stage grouting comprises a first reagent and a second reagent, wherein the first reagent is formed by mixing sodium silicate and water according to the mass ratio of 1 (1.4-1.8), and the second reagent is formed by mixing cement and water according to the mass ratio of 1 (4-6). For example, the slurry of the second stage grouting may be 208 kg of sodium silicate, 339 kg of water in the first agent, 94 kg of cement and 472 kg of water in the second agent per cubic meter of the furnish. As shown in fig. 5, during the second stage grouting, the upstream of the
Can compensate the defect of a grout through secondary grout in this application for the stratum obtains effectual reinforcement stagnant water effect. The grout enters a double-ring plug pipe in the grouting pipe after being pressurized by a grouting pump, and then a rubber sleeve wrapped outside is expanded and the outer skin grout is crushed through a leak hole formed in the grouting pipe. When the pressure is increased to a certain degree, the pressurized slurry can be filled, permeated and compacted along the stratum structure, the subsequent slurry continuously extends outwards under the action of the pressure, and the slurry forms a consolidated body in the soil body, so that the aims of increasing the stratum strength and reducing the stratum permeability are fulfilled.
(2.7) the grouting process is carried out from the bottom, and can be carried out in a section of 330mm, and after each section is finished, the grouting process is moved upwards by 330mm until the ground is available. And drilling and coring are carried out after grouting is finished, a sample is extracted for carrying out a compression resistance test, and the next procedure is carried out after the test result meets the design requirement. Fig. 7 is a schematic plan view of a space enclosing structure of a steel pipe pile region formed after the grouting curtain construction work is completed. In fig. 7, the steel pipe piles 21 and the grouting holes 22 are respectively arranged at intervals, and the steel pipe piles 21 and the grouting holes 22 in adjacent rows are arranged in a staggered manner, so that the purpose of preventing leakage is achieved.
By adopting the grouting method, the grout is injected into the rock-soil layer under higher pressure, the packers above and below the double-ring plug pipe can realize segmented layered grouting, and continuous or interval grouting can be selected according to construction requirements, so that both loose strata and denser strata can obtain good grouting reinforcement effect; the method has the obvious advantages that repeated grouting is carried out on any section in a grouting area, different grouting materials can be adopted in the same grouting pipe, different grouting pressures are selected, the construction technology is safe and reliable, gaps in the stratum can be fully filled through secondary grouting, and the stratum can obtain a more effective reinforcing and water stopping effect; different grouting parameters and grouting materials can be selected according to different geological and hydrological condition characteristics of each region, and because grouting construction generally passes through a plurality of different geological structures, the slurry absorption capacity of various stratums and the diffusion action mechanism of the slurry in different stratums are different, and the adoption of different grouting materials and grouting parameters has a decisive effect on the construction effect.
Although the embodiments disclosed in the present application are described above, the descriptions are only for the convenience of understanding the present application, and are not intended to limit the present application. 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 disclosure as defined by the appended claims.
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