CN114808923A - Cave grouting construction processing method - Google Patents
Cave grouting construction processing method Download PDFInfo
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- CN114808923A CN114808923A CN202210410029.1A CN202210410029A CN114808923A CN 114808923 A CN114808923 A CN 114808923A CN 202210410029 A CN202210410029 A CN 202210410029A CN 114808923 A CN114808923 A CN 114808923A
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D3/00—Improving or preserving soil or rock, e.g. preserving permafrost soil
- E02D3/12—Consolidating by placing solidifying or pore-filling substances in the soil
- E02D3/123—Consolidating by placing solidifying or pore-filling substances in the soil and compacting the soil
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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
- E02D15/04—Placing concrete in mould-pipes, pile tubes, bore-holes or narrow shafts
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D33/00—Testing foundations or foundation structures
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Abstract
The invention discloses a cave grouting construction processing method, which adopts different modes to perform grouting according to different sizes and types of caves. Specifically, cement paste is injected into the first cave through the corresponding grouting hole; when cement slurry is injected, the grouting pressure is gradually increased from a preset first initial pressure until a preset first grouting final pressure is reached, and multiple times of grouting are carried out; cement mortar is injected into the second cave through the corresponding grouting holes; when cement mortar is injected, the grouting pressure is increased step by step from a preset second initial pressure until a preset second grouting final pressure is reached; the second initial pressure is greater than the first initial pressure, and the second grouting final pressure is greater than the first grouting final pressure. And finishing grouting of the grouting hole after the grouting of the grouting hole reaches the preset condition. Carry out the effectual foundation that has consolidated of slip casting processing to the cave. Adopt different modes to slip casting to the cave of different sizes and types, the slip casting is effectual.
Description
Technical Field
The invention relates to the field of buildings, in particular to a cave grouting construction processing method.
Background
In China, the most prominent problem of damage to various engineering buildings including high-speed railways caused by karst is that the karst collapses or sinks unevenly under the action of underground water, and diseases of karst subgrades can be divided into two categories: one is the deformation problem and the other is the water hazard problem. In particular to a large railway station house, the design service life of the large railway station house is 100 years, the design standard of the foundation is high, and the requirement on settlement is strict. Therefore, reinforcement treatment is required for the ground of the karst development area.
Disclosure of Invention
In view of the above technical problems, embodiments of the present invention provide a method for treating cave grouting construction, which aims to reinforce a foundation.
An embodiment provides a method for processing cave grouting construction, which includes:
surveying the foundation area to obtain the position, size, quantity and type of the cave below the foundation area; dividing the cave into a first cave and a second cave according to the size and the type of the cave;
the drilling machine drills a grouting hole communicated with the first cave and a grouting hole communicated with the second cave;
cement paste is injected into the first cave through the corresponding grouting holes; when cement slurry is injected, the grouting pressure is gradually increased from a preset first initial pressure until a preset first grouting final pressure is reached, and multiple times of grouting are carried out;
cement mortar is injected into the second cave through the corresponding grouting holes; when cement mortar is injected, the grouting pressure is increased step by step from a preset second initial pressure until a preset second grouting final pressure is reached; the second initial pressure is greater than the first initial pressure, and the second grouting final pressure is greater than the first grouting final pressure;
and finishing grouting of the grouting hole after the grouting of the grouting hole reaches the preset condition.
In the method provided by one embodiment, the final pressure of the first grouting is one of 1.0-1.2MPa, and the variation range of the grouting pressure is 0.4-1.2 MPa during the grouting of the cement slurry; the final pressure of the second grouting is 7.0-8.0MPa, and the variation range of the grouting pressure is 4.0-10.0MPa during the injection of the cement mortar.
An embodiment provides the method, wherein the dividing the cavern into a first cavern and a second cavern according to the size and the type of the cavern comprises:
determining a fully-filled cave as a first cave; and/or the presence of a gas in the gas,
determining a half-filled or unfilled cave with the hole diameter of 2.0-4.0 m as a first cave; and/or the presence of a gas in the gas,
determining a beaded cave with the hole diameter of more than or equal to 4.0 m as a first cave; and/or the presence of a gas in the gas,
and determining a half-filled or non-filled cave with the hole diameter being more than or equal to 4.0 meters as a second cave.
In one embodiment, the method provides that the cement slurry is prepared from: 42.5-grade ordinary portland cement and water are mixed by a mixing ratio of 1: 1 in a mass ratio; the cement mortar adopts plain cement mortar with the mark number between M10 and M20.
An embodiment provides the method, wherein the drilling machine drills a grouting hole communicated with the first cavity and a grouting hole communicated with the second cavity, and the method comprises the following steps:
calibrating the positions of the drill holes corresponding to the first cave and the second cave according to preset design requirements;
moving the drilling machine to a calibrated drilling position, and adjusting the angle of the drilling machine after the drilling machine is in place to enable the drilling machine to be vertical;
the hole forming adopts a geological drilling method of coring in whole holes, the hole diameter of the open hole is not less than 110mm, and the hole diameter of the final hole is not less than 91 mm; filling drilling records in the drilling process, recording whether the hole has water turning and water leakage and a soil layer boundary in the drilling process, and putting the cores orderly according to the sequence.
An embodiment provides the method, further comprising:
after drilling, putting a guide pipe into the drill hole to the bottom of the hole, introducing water, and washing the hole from the bottom of the hole to the outside by water flow until clear water returns for 5-10 min; wherein the flushing pressure is 80% of the grouting pressure.
An embodiment provides the method, wherein the preset condition includes at least one of the following three conditions:
the pressure of a grouting orifice is basically maintained at 1.0MPa and stabilized for 10 min;
the grout outlet point is 3-5m out of the grouting range;
the single-hole grouting amount reaches 1.5-2.0 times of the average grouting amount, and the grouting amount is reduced.
An embodiment provides the method, further comprising:
selecting a plurality of grouting holes, and performing water pressing tests on the selected grouting holes before and after grouting to obtain the water absorption capacity per unit length; compared with the water absorption per unit length before grouting, if the water absorption per unit length after grouting is reduced by 95-99%, the grouting effect is determined to be obvious.
An embodiment provides the method, further comprising:
and after grouting is finished, drilling in the estimated grouting diffusion range to verify the grouting diffusion range, and measuring in the cave by adopting a standard penetration method, wherein the standard penetration value is qualified after 10 hits.
An embodiment provides the method, which comprises the following steps:
when the grouting pressure is injected to the upper part, if the grouting pressure is not changed or is changed from large to small, the pressure does not reach the preset pressure after the grouting is carried out for the preset time, and the grouting amount exceeds the preset grouting amount by the range exceeding the preset threshold value, the cave is judged to be an open cave;
and detecting the boundary of the open cave again, and after the boundary is determined, injecting a waterproof curtain by using double-liquid grout around the boundary, wherein the waterproof curtain is subjected to intermittent and fractional grouting for 1-4 times within 6-10 hours.
The cave grouting construction processing method provided by the embodiment of the invention adopts different modes to perform grouting according to different sizes and types of caves. Specifically, cement slurry is injected into the first cave through the corresponding grouting hole; when cement slurry is injected, the grouting pressure is gradually increased from a preset first initial pressure until a preset first grouting final pressure is reached, and multiple times of grouting are carried out; cement mortar is injected into the second cave through the corresponding grouting holes; when cement mortar is injected, the grouting pressure is increased step by step from a preset second initial pressure until a preset second grouting final pressure is reached; the second initial pressure is greater than the first initial pressure, and the second grouting final pressure is greater than the first grouting final pressure. And finishing grouting of the grouting hole after the grouting of the grouting hole reaches the preset condition. Carry out the effectual foundation that has consolidated of slip casting processing to the cave. Adopt different modes to slip casting to the cave of different sizes and types, the slip casting is effectual.
Drawings
FIG. 1 is a flowchart of an embodiment of a method for grouting a cave according to the present invention;
FIG. 2 is a detailed flow diagram of the cave grouting construction processing method provided by the present invention;
FIG. 3 is a detailed flowchart of step 2;
FIG. 4 is a schematic diagram of the effect of karst grouting profile.
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.
The cave grouting construction treatment method provided by the invention is suitable for the projects of railways, roads, house buildings and the like which need foundation reinforcement treatment in a karst development area; the method is suitable for projects with large underground water fluctuation and strict control on settlement after foundation construction. The method mainly comprises the steps of drilling and grouting a karst foundation to fill caves (such as soil caves, karst caves and corrosion cracks); and sealing the soil and stone interface to form a waterproof curtain to block the connection between the upper layer of stagnant water and the karst water and prevent the foundation from collapsing. This is explained in more detail below by means of some examples.
As shown in fig. 1 and 2, the method for treating cave grouting (construction process) provided by the invention comprises the following steps:
And drilling holes at a plurality of point positions of the foundation area to obtain punching data. After drilling, according to the rock and soil layer taken out from the drill hole, it can find out whether there are various information of soil cave, karst cave, groove, crack and stratum distribution. And similarly, determining the boundary of the cave range by adopting the drilling holes, scribing the boundary, enclosing the cave range, and obtaining the position, the size, the quantity and the type of the cave below the foundation area by combining the data of drilling holes and soil taking.
And (4) analyzing plane and vertical distribution characteristics of karst cave (soil) and karst ditch, karst groove, corrosion crack and the like according to the investigation result, and determining a karst treatment method according to the size of a cave body, the characteristics of karst cave fillers and hydrogeological conditions. For large-scale holes and medium holes, cement mortar is mainly poured for treatment. For a solution ditch, a solution tank, a karst collapse area and a foundation uniformity mutation area influenced by karst, a uniform foundation is built mainly in a consolidation or reinforcement mode, so that accidents such as head falling, collapse and toppling of construction equipment are prevented; for small holes and joints and corrosion cracks which may generate gushing, single-fluid grouting sleeve valve pipe grouting treatment is mainly adopted. When the foundation pit has gushing and water inrush during construction, the foundation pit is divided into blocks to be subjected to system reinforcement treatment.
According to the development condition of karst revealed by the detailed exploration drilling and the advanced drilling, the comprehensive analysis and selection of a more appropriate karst foundation treatment method are combined with the characteristics of the engineering structure. For example, the cavern division can be performed basically as follows:
(1) a fully filled cavity is determined as the first cavity.
(2) And determining a half-filled or unfilled cave with the hole diameter of 2.0-4.0 meters as the first cave.
(3) And determining the beaded cave with the hole diameter of more than or equal to 4.0 m as the first cave.
For the first cave, sleeve valve pipes can be used for grouting subsequently, and single-liquid cement slurry is used as grouting materials.
(4) And determining a half-filled or non-filled cave with the hole diameter being more than or equal to 4.0 meters as a second cave. For the second cavity, the filling method can be adopted subsequently, namely the drilling hole is used as a feeding hole to be filled with cement mortar, and the filling material is low-grade cement mortar (M10-M20).
And step 22, after the grouting hole position is calibrated, moving the drilling machine to the calibrated drilling position, and after the drilling machine is in place, adjusting the angle of the drilling machine by using tools such as a slope ruler, a horizontal ruler and the like to ensure that the drilling machine is vertical, firm in installation and stable in positioning.
And 23, after the drilling machine is installed, the center of the vertical shaft, the center of the orifice pipe and the center of the hole site are consistent, and the direction is consistent with the design. The drilling uses a long and large diameter, and the large diameter of the guide is preferably used when the hole is deep. The drilling machine needs to be installed firmly, positioned stably and fixed. And drilling is carried out only after the verticality deviation of the drill rod is not more than 1%, the hole position deviation is not more than 0.5m, and the hole forming quality is ensured. Various devices need to be installed and fixed with pipelines nearby, and are not suitable to be too long so as to prevent pressure and flow consumption.
The hole is drilled by a geological drilling method using coring of the whole hole, and the hole diameter is not less than 110mm (i.e., the hole diameter is not less than 110mm), and the hole diameter of the final hole is not less than 91mm (i.e., the hole diameter is not less than 91 mm). When earth surface is covered with soil, in order to prevent the orifice from collapsing or shrinkage, an orifice pipe can be placed downwards or drilling can be carried out by adopting a pipe following mode. Filling drilling records in the drilling process, recording whether the hole has water turning and water leakage and a soil layer boundary in the drilling process, putting the cores orderly according to the sequence of times, and simultaneously paying attention to the protection of the cores until grouting is finished.
Monitoring hole deviation, and when the hole deviation exceeds a preset specified requirement, comprehensively analyzing the grouting data and the quality inspection condition of the part, and taking remedial measures such as plugging holes, re-drilling and the like when determining that the grouting quality is influenced. The deviation of the hole position is not more than 50 cm.
When the drilling hole is collapsed and falls, a cavity crack and a lost stratum are difficult to drill, the reason of the position is determined, grouting treatment can be carried out firstly, then drilling is carried out, and a top-down grouting hole forming mode can also be adopted.
After the hole is formed, grouting is waited, and the hole opening is sealed and covered, so that the protection is properly performed.
And 24, after drilling is finished, putting a grouting pipe into the drilled hole to the bottom of the hole, connecting the grouting machine, pumping clear water to clean the hole, and washing the hole from the bottom of the hole to the outside through water flow until the clear water returns for 5-10 min. The pipe diameter of the grouting pipe can be selected from 50 mm-130 mm, the pipe diameter within the pipe diameter range is adopted for grouting based on design requirements and actual conditions, the grouting effect can be controlled under the condition of effectively controlling grouting pressure and slurry ratio, and the pipe is convenient to purchase. If the thickness of the bottom sediment of the hole exceeds 20cm, the bottom sediment of the hole is continuously washed by clear water until the thickness of the bottom sediment of the hole does not exceed 20 cm; the flushing pressure is 80% of the final pressure of the grouting. And after the flushing is finished, grouting can be performed.
And 2, drilling to obtain grouting holes of various cavities such as karst caves. Before grouting, a water pressing test is carried out, and technological parameters such as material proportion, grouting pressure and the like are adjusted. Grouting is still carried out after the detection of the water-pressurizing test drilling hole is finished. Specifically, a plurality of grouting holes are selected, and a water pressing test is performed on the selected grouting holes before grouting to obtain the water absorption capacity per unit length. The water absorption per unit length means the water absorption per unit time (L/min) per unit length (1m) under a pressure of 0.01MPa (or 1m water column).
And 3, grouting, comprising: and (3) inserting grouting pipes into the grouting holes, and timely plugging orifices (plugging gaps between the grouting holes and the grouting pipes) and nearby ground cracks to prevent grout leakage. If these operations are completed in step 24, the slurry may be directly injected. And cement slurry is injected into the first cave through the corresponding grouting pipe in the grouting hole, and the grouting flow rate can be controlled to be 30-75L/min. Cement mortar is injected into the second cave through the grouting pipes in the corresponding grouting holes, the grouting flow rate can be determined according to the actual situation on site, and pipe blockage in the grouting process is avoided.
The grouting sequence in the karst area directly influences the grouting compactness of karst (soil) holes and karst cracks and the grouting slurry loss, and the grouting sequence is preferably as follows:
1) the construction sequence of the karst (soil) cave treatment is as follows: detecting a boundary, grouting and filling, and detecting a grouting effect.
2) Sequential separate injection is to be followed, namely, a mode of adopting different grouting sequences according to different sizes of karst caves is followed, and the small caves are arranged from the outside to the inside: namely, a plurality of grouting holes are also drilled in the small holes, grouting is firstly carried out through the grouting holes close to the boundary, and then grouting is carried out through the grouting holes close to the center of the cave; big hole is big after inside and outside first, and is big after big, and is lower before upper: namely, the grouting pipe is inserted into the bottom of a large karst cave (the large karst cave and the small karst cave are relative concepts), and grouting slurry is filled from the bottom of the karst cave to gradually fill the large karst cave upwards; the grouting pressure is first small and then large. If the grouting amount is large when the peripheral holes are grouted for the first time and the pressure does not meet the design requirement, grouting in a mode of separating one jump is adopted, and then grouting is carried out on the holes which are not grouted for the first time.
Because the unit grouting amount is closely related to the grouting hole distance, the grouting pressure, the slurry concentration and the development degree of karst, in the embodiment, a field grouting test is performed before grouting construction, a grouting process is reasonably selected, relevant parameters such as the grouting pressure, the slurry proportion, the unit grouting amount and the like are reasonably determined, and the condition for stopping grouting and the like are determined. The details will be described below.
Specifically, 42.5-grade ordinary portland cement is adopted, and the mass ratio of the cement to water is 1: 1, preparing cement paste. The cement mortar adopts plain cement mortar with the mark number between M10 and M20. The grouting can be started after the grout for grouting is fully and uniformly stirred by the stirrer, and the grout is continuously and slowly stirred in the grouting process, wherein the stirring time is less than the initial setting time of the grout. The slurry should be filtered through a screen before pumping. And the experimenter is responsible for monitoring the mixing of the slurry on site and performing sampling detection so as to ensure the mixing quality of the slurry. The slurry containing barrel and the grouting pipeline must not be exposed to the sun to prevent the slurry from solidifying. In other words, the pulp containing barrel and the grouting pipeline are shaded.
The invention adopts cement paste and cement mortar, the cement paste mainly comprises cement and sand, and the material source is wide. Under the conditions of fast flow rate of underground water, corrosive elements contained, large water content of soil or high strength requirement of a solidification body, a proper amount of additive can be added into cement to achieve the effects of quick setting, high strength, frost resistance, corrosion resistance, no precipitation of slurry and the like.
When cement slurry is injected, the grouting pressure is gradually increased from a preset first initial pressure until a preset first grouting final pressure is reached, and multiple times of grouting are carried out. In other words, the grouting pressure is carried out according to the principle of initial small pressure and final large pressure, namely the pressure is suitable to be gradually increased at graded intervals, and the grouting is gradually strengthened for multiple times at the first time with relatively small pressure. The grouting control pressure is generally 0.4-1.2 MPa, namely the variation range of the grouting pressure is 0.4-1.2 MPa during the cement slurry injection period; and grouting for 3-4 times. The final pressure of the first grouting is generally controlled to be 1.0-1.2 MPa. Therefore, according to different geological conditions, the invention adopts graded pressurization, can adjust the pressure suitable for grouting of the hole and ensures the grouting effect and safety.
When cement mortar is injected, the grouting pressure is increased step by step from the preset second initial pressure until the preset second grouting final pressure is reached. In other words, the grouting pressure is carried out according to the principle of initial small pressure and final large pressure, namely the pressure is suitable to be gradually increased at graded intervals, and the grouting is gradually strengthened for multiple times at the first time with relatively small pressure. The grouting pressure is generally controlled to be 4.0-10.0MPa, namely the variation range of the grouting pressure is 4.0-10.0MPa during the cement mortar injection. The final pressure of the second grouting is generally controlled to be 7.0-8.0 MPa. It can be seen that the second initial pressure is significantly greater than the first initial pressure and the second final grouting pressure is significantly greater than the first final grouting pressure. Similarly, the pressure suitable for grouting of the hole can be adjusted by adopting graded pressurization, and the grouting effect and safety are ensured.
During grouting construction, an automatic flow and pressure recording meter is adopted, and flow and pressure data are arranged and analyzed in time. The flow and pressure are controlled as much as possible in the grouting process, so that the loss of the slurry is prevented. When the grouting pump is started or closed, the chemical grouting pump must be started or closed firstly so as not to block the pipeline.
And recording, sorting and analyzing technical data and basic data in the whole grouting process. And ground observation records (horizontal displacement, the position of a slurry emitting point, ground subsidence and the like) are enhanced in the grouting process. The grouting process is environment-friendly, and slurry pollutants are timely cleaned. After the field level is generally arranged, temporary drainage facilities are repaired around the grouting field level. In the karst grouting construction area, ground surface observation is enhanced, ground surface deformation monitoring is also enhanced, ground surface deformation monitoring is carried out every day during construction, ground surface deformation is actually measured, the measurement precision is not more than 1mm, detailed records are made, and grouting pressure is controlled according to observation data so as to avoid influencing the stability of the graben slope or the safety of nearby structures.
And 4, judging whether the grouting of the grouting hole reaches a preset condition, and if so, finishing the grouting of the grouting hole. The preset condition may include at least one of the following three:
the pressure of a grouting orifice is basically maintained at 1.0MPa and stabilized for 10 min;
the grout outlet point is 3-5m out of the grouting range;
the single-hole grouting amount reaches 1.5-2.0 times of the average grouting amount, and the grouting amount is obviously reduced, if a field technician observes the obvious change before and after the grouting amount, the conclusion that the grouting of the grouting hole needs to be finished is obtained.
And if the grouting of the grouting hole does not reach the preset condition, cleaning the hole and grouting again. Specifically, the grouting is continuously performed for a preset time, and if the grouting duration does not meet the end standard, the hole cleaning is performed for grouting again, and the preset time can be set as required, such as half an hour.
In the karst grouting construction, aiming at the situation that the grouting hole can not reach the grouting end condition all the time, the following measures are adopted through analyzing the formed reason:
(1) collapse when encountering a large karst cave in the pore-forming process:
1) if the hole collapse is not serious after a large cave is met in the construction process, backfilling the mixture of the rubble and the clay blocks.
2) If the whole hole collapses, after the collapse is stable, the hole is backfilled to the ground surface by clay, and after compaction, the karst cave pretreatment is carried out, wherein the treatment method is the same as the karst cave treatment method. And after the karst cave is pretreated, the hole is formed again, namely, the cave grouting construction treatment is restarted on the cave.
(2) And (3) seriously running slurry during grouting of a soil cave:
when grouting is carried out from the lower part to the upper part of the cave, if the grouting pressure is not changed or is changed from large to small, the pressure does not reach the preset pressure after the grouting is carried out for a preset time (if the pressure does not come after the grouting is carried out for a period of time), and the grouting amount exceeds the preset grouting amount by more than a preset threshold (the grouting amount is far more than the estimated calculated amount), the cave is judged to be an open cave. And then detecting the boundary of the open cave again, and after the boundary is determined, injecting a waterproof curtain around the boundary by adopting double-liquid grouting, wherein the waterproof curtain adopts intermittent and fractional grouting, and the intermittent time is 6-10 hours and 1-4 times of grouting. Wherein, the double-fluid slurry can be formed by mixing cement slurry and water glass slurry, and the mass ratio of the cement slurry to the water glass slurry is 1: 0.5 to 1: 1. And after the waterproof curtain is constructed, performing jump hole grouting from outside to inside.
(3) If large-area collapse occurs due to a large cave in the field implementation process, or if the large cave is proved or the large-area collapse is expected to occur before the implementation, a construction unit is required to be quickly connected with relevant departments, and corresponding countermeasures are adopted on the field for remediation.
And carrying out a water pressing test on the selected grouting hole after grouting to obtain the water absorption capacity per unit length. Compared with the water absorption per unit length before grouting, if the water absorption per unit length after grouting is reduced by 95-99% (the difference between the water absorption per unit length before and after grouting is great), the grouting effect is determined to be obvious; otherwise, the grouting effect is not obvious, and if not, the hole washing and grouting are carried out again. And (4) carrying out grouting effect inspection by adopting a pressurized-water test, and evaluating the grouting effect by combining construction process data according to a quality inspection result.
And after grouting is finished, drilling in the estimated grouting diffusion range to verify the grouting diffusion range, and measuring in the cave by adopting a standard penetration method, wherein the standard penetration value is qualified after 10 hits.
Therefore, the method adopts karst grouting to carry out foundation reinforcement treatment. After the karst grouting treatment, the risk of collapse of the pile foundation during construction can be effectively reduced; the risk of rapid development of the soil cave under the action of underground water is prevented, and the risk of later-stage operation is reduced; the method can prevent the damage of the surrounding buildings and structures of the foundation pit caused by outburst and gushing of water when the undetected caves and karst channels are excavated in the foundation pit, improve the capability of resisting karst local collapse of the sand foundation and improve the safety of a station structure.
The construction process provided by the invention mainly comprises the steps of drilling and grouting the karst foundation to fill soil caves, karst caves and corrosion cracks; and sealing the soil and stone interface to form a waterproof curtain to block the connection between the upper layer of stagnant water and the karst water and prevent the foundation from collapsing.
During grouting, cement paste or mortar enters the karst cave under the pressure condition, so that the slurry is uniformly diffused in the karst cave, and fillers of the karst cave are bonded into a whole, thereby reducing the risks of ground settlement, collapse and the like and ensuring the construction safety; simultaneously, the bearing capacity of the foundation is improved, the safety of a station structure is improved, and the later-stage operation safety is ensured.
The karst grouting is applied to the projects such as railways, highways, house buildings and the like which need foundation reinforcement treatment in the karst development area; the method has obvious application effect on geological conditions such as close communication between surface water and underground water, poor foundation stability and the like.
Compared with other geological processing methods, the construction process is simpler and more convenient, has smaller operation difficulty and faster construction, and requires flexible operation equipment. The method comprises the following specific steps:
(1) the construction method carries out grouting treatment on the found karst cave, for the cement grouting, one background can be connected with a plurality of grouting pipes, and a plurality of grouting holes can carry out grouting simultaneously, so that the construction efficiency is high, and the labor cost is saved.
(2) According to the construction method, the karst cave grouting construction is carried out before the pile foundation construction, the karst cave is densely filled, the risks of ground settlement, collapse and the like are reduced, and the construction safety is ensured; meanwhile, the bearing capacity of the foundation is improved, the safety of a station structure is improved, the operation safety of a railway station is ensured, and good social benefits are formed.
From the field practice, the construction method is flexible and mobile, the construction machinery is simple, a large number of machines can be simultaneously carried out, the construction method has great advantages under the condition of a certain construction period and a certain number of mechanical equipment, the mechanical type is single in construction, and the construction quality is easily guaranteed. Through field practice, the grouting effect can completely meet the requirements, and the grouting material has good effects on foundation reinforcement and post-construction settlement control, and has good social benefit, economic benefit and popularization value.
The above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (10)
1. A cave grouting construction processing method is characterized by comprising the following steps:
surveying the foundation area to obtain the position, size, quantity and type of the cave below the foundation area; dividing the cave into a first cave and a second cave according to the size and the type of the cave;
the drilling machine drills a grouting hole communicated with the first cave and a grouting hole communicated with the second cave;
cement paste is injected into the first cave through the corresponding grouting holes; when cement slurry is injected, the grouting pressure is gradually increased from a preset first initial pressure until a preset first grouting final pressure is reached, and multiple times of grouting are carried out;
cement mortar is injected into the second cave through the corresponding grouting holes; when cement mortar is injected, the grouting pressure is increased step by step from a preset second initial pressure until a preset second grouting final pressure is reached; the second initial pressure is greater than the first initial pressure, and the second grouting final pressure is greater than the first grouting final pressure;
and finishing grouting of the grouting hole after the grouting of the grouting hole reaches the preset condition.
2. The method of claim 1, wherein the final pressure of the first grouting is one of 1.0-1.2MPa, and the grouting pressure varies from 0.4-1.2 MPa during the grouting; the final pressure of the second grouting is 7.0-8.0MPa, and the variation range of the grouting pressure is 4.0-10.0MPa during the injection of the cement mortar.
3. The method according to claim 1 or 2, wherein said dividing the caverns into a first cavern and a second cavern by size and type of cavern comprises:
determining a fully-filled cave as a first cave; and/or the presence of a gas in the gas,
determining a half-filled or unfilled cave with the hole diameter of 2.0-4.0 m as a first cave; and/or the presence of a gas in the gas,
determining a beaded cave with the hole diameter of more than or equal to 4.0 m as a first cave; and/or the presence of a gas in the gas,
and determining a half-filled or non-filled cave with the hole diameter being more than or equal to 4.0 meters as a second cave.
4. The method of claim 1, wherein the cement slurry is prepared from: 42.5-grade ordinary portland cement and water are mixed by a mixing ratio of 1: 1 in a mass ratio; the cement mortar adopts plain cement mortar with the mark number between M10 and M20.
5. The method of claim 1, wherein the drilling machine drills a grout hole in communication with the first cavity and a grout hole in communication with the second cavity, comprising:
calibrating the positions of the drill holes corresponding to the first cave and the second cave according to preset design requirements;
moving the drilling machine to a calibrated drilling position, and adjusting the angle of the drilling machine after the drilling machine is in place to enable the drilling machine to be vertical;
the hole forming adopts a geological drilling method of coring in whole holes, the hole diameter of the open hole is not less than 110mm, and the hole diameter of the final hole is not less than 91 mm; filling drilling records in the drilling process, recording whether the hole has water turning and water leakage and a soil layer boundary in the drilling process, and putting the cores orderly according to the sequence.
6. The method of claim 5, further comprising:
after drilling, putting a guide pipe into the drill hole to the bottom of the hole, introducing water, and washing the hole from the bottom of the hole to the outside by water flow until clear water returns for 5-10 min; wherein the flushing pressure is 80% of the grouting pressure.
7. The method according to claim 1, wherein the preset condition comprises at least one of the following three conditions:
the pressure of a grouting orifice is basically maintained at 1.0MPa and stabilized for 10 min;
the grout outlet point is 3-5m out of the grouting range;
the single-hole grouting amount reaches 1.5-2.0 times of the average grouting amount, and the grouting amount is reduced.
8. The method of claim 1, further comprising:
selecting a plurality of grouting holes, and performing water pressing tests on the selected grouting holes before and after grouting to obtain the water absorption capacity per unit length; compared with the water absorption per unit length before grouting, if the water absorption per unit length after grouting is reduced by 95-99%, the grouting effect is determined to be obvious.
9. The method of claim 1, further comprising:
and after grouting is finished, drilling in the estimated grouting diffusion range to verify the grouting diffusion range, and measuring in the cave by adopting a standard penetration method, wherein the standard penetration value is qualified after 10 hits.
10. The method of claim 1, comprising:
when the grouting pressure is injected to the upper part, if the grouting pressure is not changed or is changed from large to small, the pressure does not reach the preset pressure after the grouting is carried out for the preset time, and the grouting amount exceeds the preset grouting amount by the range exceeding the preset threshold value, the cave is judged to be an open cave;
and detecting the boundary of the open cave again, and after the boundary is determined, injecting a waterproof curtain by using double-liquid grout around the boundary, wherein the waterproof curtain is subjected to intermittent and fractional grouting for 1-4 times within 6-10 hours.
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| CN115110523A (en) * | 2022-08-04 | 2022-09-27 | 中国水利水电科学研究院 | Grouting repair method for integrity defects of screw pile |
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