CN108999195B - It is a kind of block the larger water burst of deep-foundation side wall stratum in the safe grouting construction process of step heap weir formula - Google Patents

Abstract

The present invention discloses formula safe grouting construction process in step heap weir in a kind of stratum of closure larger water burst of deep-foundation side wall.It include: to be observed the water yield and quantity of sand and mud of foundation pit deep side wall, calculated；Tapping pipe is arranged in issue to sluice；Back-pressure body is set around issue, back-pressure is formed to the foundation pit side-wall around issue；It is drilling on the ground of side wall where issue, is drilling and be at least divided into two rows, it is the first row hole drilling by proximal wall prop that the depth of the first row hole drilling and the second row hole drilling, which is in up/down steps formula, is successively reduced according to sequence, drilling depth outward；Slip casting blocks.The vertical drilling of rapid construction on the ground of the side-wall outer side locating for the issue of foundation pit deep, aggregate is injected into the cavity of conduit pipe or formation and with the anti-slurries for dispersing early strong rapid hardening by drilling, the curtain that blocks water quickly is formed in water burst stratum, block underground water gushing channelway, reach and quickly administer water burst, the purpose of grouting and reinforcing is carried out to the stratum destroyed by water burst.

Description

A kind of safety grouting of step and weir type in the formation to block the large water gushing from the side wall of deep foundation pit construction technology

technical field

The invention belongs to the field of grouting plugging of relatively large water gushing deep in the side walls of deep foundation pits such as urban subway tunnels and buildings, and in particular relates to a step stacking weir type safety grouting in strata for sealing large water gushing in the side walls of deep foundation pits construction process.

Background technique

When constructing urban subway tunnel stations and excavating deep foundation pits for high-rise buildings, it is often encountered that there is a large water gushing phenomenon with a water volume of not less than 10m ³ /h on the deep side walls of the foundation pit. After the flooding, it brought a great security threat to the project. After analysis, the sources of water gushing in the deep part of the deep foundation pit are mainly underground diving, lateral recharge of surface rivers, or serious leakage of underground pipelines (sewage, rainwater, etc.). Water gushing points are generally located in loose strata such as miscellaneous fill, gravel, silt, silt, or soil-rock joints. This type of formation has high porosity and strong water conductivity. Because the water gushing deep in the foundation pit has a certain pressure, it presents a concentrated stream of relatively large flow of water gushing in the form of a jet. After the water gushing outlet is temporarily blocked, the water level will rise rapidly, and there will be many water gushing phenomena at other positions on the side wall of the foundation pit, which will greatly harm the stability of the side wall. When a large water gushing occurs in a deep foundation pit, the gushing water will rush out in strands and carry a large amount of sediment. If the gushing water cannot be effectively treated, a large amount of sand will burst out, forming cavities in the surrounding strata at the gushing point, causing the overlying strata to subside, and even causing ground subsidence; the side wall of the foundation pit is under the dynamic load of stratum subsidence , there will be serious instability, the collapse of the side wall of the foundation pit and its supporting body, and serious water and mud inrush accidents will occur.

When there is a small water gushing in the foundation pit (such as shady water on the side wall, scattered point-like water seepage in a large and large area, or small strand-like water gushing, etc.), when it is considered that there will be no major danger after analysis, generally A common treatment method is to construct a grouting anchor rod on the side wall at the water gushing point, and the grouting anchor rod plays a dual role of anchoring and grouting after grouting. Use the grouting bolt to inject cement slurry or chemical slurry into the gap behind the support body of the side wall of the foundation pit to block the phenomenon of small water gushing. Due to the small amount of water and the weak ability to carry sediment under the condition of shady water seepage, it will not cause serious subsidence of the strata behind the foundation pit wall in a short period of time, so there will be no serious stratum subsidence and instability disasters . However, once a large amount of long-lasting strand-shaped water gushing occurs, it shows that the gushing water has a strong water supply capacity and a relatively smooth water-conducting channel. Due to the certain pressure, the water flow velocity is relatively high, the ability to scour and destroy the surrounding rock of the aqueduct is strong, and the ability to carry sediment is strong, and the strata around the aqueduct will be evacuated quickly, and the surface subsidence will occur. Serious accidents such as pit side wall collapse or even water and mud inrush. In this case, the grouting method using side wall bolts is difficult to meet the requirements of continuous large-scale grouting due to the small amount of grouting, and the grouting depth of the bolts is shallow, which is top water grouting opposite to the direction of water flow. The grout diffusion range is small, most of the injected grout is washed out by the water flow, the water blocking effect is poor, and the construction period is long. It is possible that serious collapse and subsidence accidents will occur before the treatment effect is achieved. Moreover, construction workers have to be close to the side wall of the gushing water, which poses a high risk to personal safety.

Patent CN201710977510.8 discloses a rapid emergency grouting plugging method for foundation pit water gushing, which includes the following steps: timely back pressure and pressure relief pipe placement after the danger occurs; determine the position of the water outlet point of the foundation pit, and the distance between The surface drilling construction is carried out at a certain position of the cast-in-place pile, that is, the axial position of the rotary grouting pile. When the drilling construction reaches the position of the water guide channel, a certain length of casing is lowered and the PVC pipe is lowered to the position of the water guide channel; the grouting pump pipeline Connect with the PVC pipe, turn on the grouting pump to pump the single liquid of cement slurry; when the cement slurry is observed to flow out from the pressure relief pipe, start injecting quick-setting grout, and the slurry will harden rapidly in the water guide channel until the pressure relief pipe No more water flows out, so far the complete blocking of the water guide channel is realized. This method can realize rapid sealing of water inrush on the side wall of the foundation pit, and plays an important role in emergency treatment of water inrush disasters on the side wall of the foundation pit.

Contents of the invention

In view of the deficiencies in the above-mentioned prior art, the present invention provides a safety grouting construction technology of step and weir type in the formation to block relatively large water gushing from the side wall of a deep foundation pit. That is, vertical drilling is rapidly constructed on the ground outside the side wall where the deep water gushing point of the foundation pit is located, and aggregate and special slurry with anti-dispersion, early strength and quick-setting are injected into the water guide channel or the formed cavity through the drilling hole. A water-blocking curtain is quickly formed in the water gushing formation to block the underground water gushing channel, so as to quickly control the water gushing and to perform grouting reinforcement on the stratum damaged by the gushing water.

In order to achieve the above object, the present invention adopts the following technical solutions:

A safety grouting construction method of step-stack weir type in strata for blocking relatively large water gushing from the side wall of a deep foundation pit, comprising:

Observe and calculate the amount of water inflow and sediment on the deep side wall of the foundation pit;

Set up a drainpipe in the water gushing point for water discharge;

Set up a back pressure body around the water gushing point to form a back pressure on the side wall of the foundation pit around the water gushing point;

Drill holes on the ground of the side wall where the water gushing point is located. The holes are divided into at least two rows. The depths of the first row of holes and the second row of holes are stepped up and down. Holes, outward according to sorting, drilling depth decreases in turn;

Grouting plugging.

Compared with the construction method in which the drilling depths of the two rows of grouting holes are the same, this application can more effectively reduce the water flow velocity at the water gushing point by forming the stepped weir type grout diffusion water blocking reinforcement body through grouting, and compared with other forward or backward types The grouting method is more targeted, it can quickly grout the water gushing point, save more grouting grout, and take into account the water-conducting formation below the perennial phreatic level. It also solves the problem of drilling with different properties in the effective space on the ground. hole needs. Different design positions and construction sequences of grouting water blocking drilling and grouting reinforcement drilling are used to achieve the dual purpose of rapid water blocking and system reinforcement.

In some embodiments, the boreholes are classified into two types: grouting water blocking boreholes and grouting reinforcement boreholes.

In some embodiments, the grouting and water plugging holes are the first row of 1-3 holes closest to the water influx point, and the first key hole should be constructed directly facing the water influx point.

In some embodiments, the grouting and water blocking drilling is constructed in two parts, the first part is a large-diameter drilling, and the second part is a grouting pipe self-advancing construction drilling.

This application adopts the method of injecting stones and hard sand aggregates into the cavity to fill the cavity by drilling with a large diameter, which can effectively reduce the water flow velocity at the water gushing point. It can better support the cavity and save plugging materials at the same time. Combining large-diameter drilling and self-propelled drilling for grouting can take into account the needs of aggregate filling and water blocking after drilling to expose stratum cavities, and at the same time meet the needs of grouting water blocking and grouting reinforcement.

In some embodiments, the distance between the position line of the first row of boreholes and the sidewall is no more than 1.5m.

In some embodiments, the first row of boreholes has the deepest grouting depth, and its grout diffusion reinforcement area is at the lowest position and completely covers the water influx point.

In some embodiments, the position of the second row of drilling slurry diffusion reinforcement areas is higher than that of the first row of grout diffusion reinforcement areas.

In some embodiments, the elevation of the upper edge of the last row of drilling slurry diffusion water blocking reinforcement is higher than or close to the perennial phreatic level there.

In some embodiments, when injecting early-strength, anti-dispersion and quick-setting grout into the grouting water blocking borehole, the valve of the drain pipe should be closed slowly; once the valve is found to be closed to a certain extent, the drain pipe has a tendency to be pushed out or the foundation pit When water seepage occurs above the water gushing point on the side wall, stop closing the valve and keep the draining state; at this time, shorten the initial setting time of the early-strength anti-dispersion quick-setting grout, keep low pressure and continue grouting; after grouting lasts for a period of time, still You can try to keep closing the valve until it is safely closed.

In some embodiments, after the valve is closed, the grouting is continued until the grouting pressure reaches the design final pressure; the design final pressure is the maximum safe pressure that does not cause cracking and swelling of the side wall support of the foundation pit.

Beneficial effects of the present invention

(1) Grouting in the formation by using different rows of boreholes to form a stepped weir grout diffusion grouting water-blocking reinforcement, which can effectively solve the problem of grouting at deeper parts in the past in large-span grouting in boreholes The technical problem that the quality is worse than the grouting quality in the shallower part. The grouting interval is reduced in a single borehole, and it is compensated by the overlap of the grouting grouting reinforced body formed by grouting in another row of boreholes to form a stepped weir-type grouted grouting water-blocking reinforced body.

(2) Using the 42mm steel pipe as the drill pipe for self-propelled drilling in deep formations reduces the risk of hole wall collapse during drilling with larger diameters; using the steel pipe as the grouting pipe can realize drilling within the range of the eye on the steel pipe. Slurry is fed uniformly within the formation interval at the same time, the slurry spreads evenly, and the overall reinforcement effect is good.

(3) The combination of large-diameter drilling and self-propelled drilling not only takes into account the water blocking of aggregate filling after the drilling exposes the stratum cavity, but also takes into account the needs of grouting water blocking and grouting reinforcement.

(4) The formation of step-stacked weir-type grout diffusion water-blocking reinforcement by grouting can be more targeted than other forward or backward grouting methods, and can quickly grout and block water gushing points, saving more grouting grout. It can better take into account the water-conducting stratum below the perennial phreatic level, and also solves the need to construct different types of boreholes in the effective space on the ground. Different design positions and construction sequences of grouting water blocking drilling and grouting reinforcement drilling are used to achieve the dual purpose of rapid water blocking and system reinforcement.

Description of drawings

The accompanying drawings constituting a part of the present application are used to provide further understanding of the present application, and the schematic embodiments and descriptions of the present application are used to explain the present application, and do not constitute improper limitations to the present application.

Figure 1: Plane layout of stepped weir grout diffusion grouting water plugging plus solid drilling in the formation;

Figure 2: Schematic diagram of the vertical section of the A-A section;

Figure 3: Schematic diagram of the drilling slurry diffusion profile at the B-B section.

Among them: 1 the first row of grouting reinforced drilling, 2 the second row of grouting reinforced drilling, 3 hole position line, 4 water gushing point, 5 foundation pit side wall, 6 grouting water blocking drilling, 7 back pressure accumulation , 8 drainage pipe, 9 bottom of foundation pit, 10 ground, 11 river, 12 perennial submerged water level line, 13 first row of drilling slurry diffusion grouting water blocking reinforcement, 14, second row of drilling slurry diffusion grouting reinforcement , 15. Step-stacked weir grout diffusion grouting water plugging reinforcement.

Detailed ways

It should be pointed out that the following detailed description is exemplary and intended to provide further explanation to the present application. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

It should be noted that the terminology used here is only for describing specific implementations, and is not intended to limit the exemplary implementations according to the present application. As used herein, unless the context clearly dictates otherwise, the singular is intended to include the plural, and it should also be understood that when the terms "comprising" and/or "comprising" are used in this specification, they mean There are features, steps, operations, means, components and/or combinations thereof.

1. Observation and calculation of water gushing volume and carried sediment volume. When strand-shaped water gushing occurs on the deep side wall of the foundation pit, an observation system should be established as soon as possible. Observe and calculate whether the gushing water changes, especially if it increases, and whether the gushing water carries a lot of sediment. If a large amount of sediment is carried, it is necessary to calculate the amount of sediment carried in the gushing water per unit time, and calculate the size of the cavity formed in the formation within a certain period of time according to the volume of the carried sediment. Through the calculation of the volume of the void that may be formed, it is predicted whether there will be a major danger. If a serious danger may occur, grouting plugging and reinforcement measures must be taken as soon as possible to deal with it.

2. Buried drain pipes for centralized drainage. Insert one or more steel pipes with a valve at one end into the water gushing point in the side wall of the foundation pit as soon as possible, keep the valve open, so that the gushing water can leak out of the drain pipe as much as possible, and the outer end of the drain pipe is connected to a plastic water pipe to lead the water to Puddles of accumulated water and drained with a pump. The gap between the outside of the steel pipe and the pit wall is closed with sandbags and quick-setting concrete. And fix the drain pipe in the side wall of the foundation pit to prevent the drain pipe from being pushed out by gushing water.

3. Pile up sandbags to form a counter pressure body. Sandbags should be piled up around the water inflow point as soon as possible. The sandbag accumulation area should be wide and thick. After the sandbags are piled up, it will have a back pressure effect on the side wall of the foundation pit around the water influx point. collapse. The formation of the sandbag anti-pressure body can also reduce the damage effect of the grouting pressure on the side wall of the foundation pit during grouting.

4. Quickly design and construct grouting drilling. Form the drilling construction conditions on the ground of the side wall where the water gushing point is located as soon as possible, and design the grouting drilling. Generally, two rows of grouting boreholes are designed around the water gushing point. The first row of drilling holes should be as close to the side wall as possible, and the distance between the hole position line and the side wall should not exceed 1.5m; the depth of the two rows of drilling holes is stepped up and down. Sort by analogy. The grouting depth of the first row of boreholes is the deepest, and its grout diffusion reinforcement area is at the lowest position and completely covers the water gushing point. The position of the second row of drill holes for the reinforcement of the grout diffusion is higher than that of the first row of the grout for the reinforcement of the diffusion. Row by row outward and so on, a stepped weir type grout diffusion grouting water blocking reinforcement is formed. The elevation of the upper edge of the stepped weir grout diffusion grouting water blocking reinforcement should exceed or be close to the perennial phreatic level there. When the level of the water-blocking reinforcement formed by the two rows of boreholes is less than the perennial phreatic level, the number of rows of boreholes can be increased.

Under the premise of satisfying the strength of grouting reinforcement, the use of step pile weir type reinforcement can effectively save the use of grouting materials, and greatly save the cost of grouting treatment of water inrush on the side wall of deep foundation pit. At the same time, the grouting reinforcement is designed in the form of steps in the stepped weir reinforcement, which can increase the energy consumption when water flows through the reinforcement. The basic principle is to use the resistance of the steps to the water flow to make the water flow form a horizontal roll between the steps, and have a strong mixing effect with the mainstream of the stepped weir reinforcement, forcing the water flow to generate strong turbulence and mixed with air, thus The purpose of dissipating the energy of the water body is achieved, thereby effectively reducing the destructive effect of the water flow on the deep foundation pit.

The strength of the reinforced body at the junction of the two grouting holes where the grout spreads is the highest, that is, on the connecting line between the centers of the two grouting holes, the drilling arrangement in this application is adopted, and a stable triangular grouting reinforcement network is formed after the grout is solidified , the grouting reinforcement formed by other drilling arrangements is more stable.

Grouting drilling is divided into two types: grouting water blocking drilling and grouting reinforcement drilling.

5. Grouting and water blocking drilling construction. The grouting water plugging holes are the key holes, which are the first row of 1 to 3 holes closest to the water inflow point, and the first key hole should be constructed directly at the water inflow point. Each key grouting drilling is divided into upper and lower parts for construction. The first part is the large-diameter drilling, and the second part is the self-advancing construction drilling of the grouting pipe. The depth of large-diameter drilling is generally 2-3m shallower than that of self-advancing construction of steel pipes.

(1) Large-diameter drilling construction. The construction depth of thick-diameter drilling is generally around the depth of the water gushing point. The drilling diameter is between 110-150mm. When the construction depth of the thick-diameter drilling is close to the water inflow point, it is necessary to closely observe whether there is a drill drop (that is, the drill pipe suddenly drops). Immediately lift the drill, and quickly lower a thick steel pipe with a diameter of not less than 108mm in the drill hole. Lower the thick-diameter steel pipe to 2m above the cavity. Fill the cavity by injecting hard aggregates such as stones and sand or soft aggregates such as kelp into the cavity through thick-diameter steel pipes. When filling the cavity, the drill bit should be lowered into the cavity and continuously rotated and stirred. During the filling process, the early-strength anti-dispersion quick-setting slurry with an initial setting time of not less than 3 minutes is injected through the drill pipe to cement the injected aggregate, or a thick single-liquid slurry with a density of not less than 1.7g/ ^cm3 is injected.

If the large-diameter borehole does not expose a cavity at the depth of the water inflow point, the drill should also be raised and the construction of the large-diameter borehole should be stopped. If the wall of the thick-diameter borehole is stable and there is no block or collapse, the steel pipe may not be lowered in the thick-diameter borehole .

In the construction of large-diameter drilling, the construction speed should be fast because of the loose ground, and thick cement slurry with sawdust should be used as flushing fluid for wall protection. When a collapsed formation is encountered, double liquid slurry should be injected for consolidation. After the aggregate fills the cavity and injects the slurry, the water gushing velocity at the water gushing point will be weakened and the water volume will be reduced.

(2) Self-advancing drilling construction of grouting pipe. Install the drill bit on the 42mm steel pipe, use the 42mm steel pipe as the drill pipe, and drill into the stratum below the large-diameter borehole, and the drilling depth is 2m below the depth of the water gushing point. Before the 42mm steel pipe is lowered into a large-diameter drill hole and used as a drill pipe, it needs to cut the eyelet and install the expansion plug. Cut eyelets on the side wall within the length range of 4m above the bottom end (because the grouting interval in the stratum is designed to be 4m), the eyelet diameter is 6mm, and the eyelets should be evenly distributed, and the number of eyelets is determined by the total area of the eyelets , the total area of the flower eye is close to the total area of the inner diameter of the grouting pipe; the expansion stopper is installed on the 42mm steel pipe, and the lower edge of the stopper is located in the large-diameter borehole or 4.5m above the bottom port of the steel pipe. After the 42mm steel pipe is used as the drill pipe to drill to the design depth, the steel pipe is no longer proposed and used as a grouting pipe. The grouting pipe is used to inject early-strength anti-dispersion quick-setting grout into the formation, and the initial setting time of the grout is generally not longer than 50s.

This application uses 42mm steel pipe as the drill pipe for self-propelled drilling in deep formations. Compared with the general method of drilling and laying casing, there are three advantages: First, the process of drilling and laying casing is carried out at the same time, which greatly saves construction time , which can deal with the major sudden disasters of deep foundation pit water inrush more quickly and efficiently; second, it reduces the risk of hole wall collapse in the construction of large-diameter drilling, and the stratum where water inrush occurs is self-stabilizing due to the presence of water. The ability is relatively weak, and self-propelled drilling can avoid drilling holes in the gap between lifting drill pipes and laying casings in general operations, and reducing its impact on emergency operations; , it can achieve uniform grouting in the strata within the range of steel pipe eyes, the grout spreads evenly, and the overall reinforcement effect is better.

The other two grouting water plugging holes on both sides of the rapid construction water gushing point have the same technical requirements as above, and their function is to supplement the first key grouting hole.

6. Construction grouting reinforcement drilling. Except for the grouting water blocking drilling, the other drillings are all grouting reinforcement drillings. The aperture structure and construction technology of the grouting reinforced boreholes are consistent with those of the grouted water blocking boreholes. The difference is that the injected slurry is high-concentration single-liquid cement slurry and early-strength quick-setting slurry whose initial setting time is not longer than 50s. The two slurries are alternately and continuously injected. The purpose of injecting single-liquid cement slurry is to use its strong consolidation strength to strengthen the formation and improve the overall strength of the strengthened formation; the purpose of alternately injecting early-strength quick-setting grout is not only to control the diffusion range of the slurry itself, but also to make it Remain within the designed diffusion range. The consolidated body formed after rapid solidification can also be used to intercept and block the diffusion of the subsequently injected single liquid slurry to the distal end, so that it remains at the proximal end of the borehole. This achieves the purpose of controlling grouting.

7. Grouting requirements. Before grouting, inject single-liquid cement slurry through the grouting pipe, and conduct a grouting test. Through the grouting test, observe the degree of single-liquid grout running out of the drain pipe and the initial pressure of grouting, and determine the early strength rate of anti-dispersion in water. The grouting initial setting time and grouting final pressure of the grouting liquid.

When injecting early-strength anti-dispersion quick-setting grout into the grouting water plugging hole, slowly close the valve of the drain pipe. Create conditions for the retention of quick-setting slurry in the formation. Once it is found that the valve is closed to a certain extent, the drain pipe tends to be pushed out or water seepage occurs above the water gushing point on the side wall of the foundation pit, stop closing the valve and keep the draining state. At this time, the initial setting time of the early-strength anti-dispersion quick-setting grout should be shortened, and the low pressure should be kept for continuous grouting. After grouting continues for a period of time, you can still try to continue closing the valve until the valve is safely closed. After closing the valve, continue grouting until the grouting pressure reaches the design final pressure. The design final pressure is generally the maximum safe pressure that does not cause cracking and swelling of the side wall support of the foundation pit.

All boreholes meet the design requirements, and the grouting water plugging and formation reinforcement are completed.

Example 1

1. Observation and calculation of water gushing volume and carried sediment volume. When strand-shaped water gushing appeared on the deep side wall of the foundation pit, a water accumulation pit was set up at the bottom of the foundation pit, and the pumping volume of the submersible pump was used to measure and calculate. According to calculations, the water inflow from the side wall is about 16.7m ³ /h, and the water flow remained stable within 5 hours of observation. And the water quality is mixed, the sediment content is about 13% (volume content). The water gushing point is located in the silt layer, and the bottom of the silt layer is clay layer. According to the analysis, the source of the gushing water is underground diving, but the possibility of replenishment by a river 200 meters away is not ruled out. The aqueduct is in the silt layer, and there is no possibility of downward transfer. The overlying rock layers on the silt layer are gravel layer, silt layer and miscellaneous filling layer. The overlying loose layer causes the safety hazard of subsidence. Grouting plugging and reinforcement measures must be taken as soon as possible for treatment.

2. Embed 8 discharge pipes with valves for centralized discharge. Insert one or more steel pipes with a valve at one end into the water gushing point in the side wall of the foundation pit as soon as possible, keep the valve open, and make the gushing water leak out from the drain pipe 8 as much as possible. The outer end of the drain pipe 8 is connected to the plastic water pipe. The water is led to a sump and pumped out. The gap between the outside of the drain pipe 8 and the side wall of the foundation pit 5 is closed with sandbags and quick-setting concrete. And the drain pipe 8 is fixed in the side wall 5 of the foundation pit to prevent the drain pipe 8 from being ejected by gushing water.

3. Accumulate sandbags to form a back pressure accumulation body 7. Sandbags should be piled up around the water inflow point 4 as soon as possible. The sandbag accumulation area should be wide and thick. After the sandbags are piled up, they will have a backpressure effect on the side wall 5 of the foundation pit around the water inflow point 4. The wall 5 bulges obliquely or even collapses. The formation of the back pressure accumulation body 7 can also reduce the damage effect of the grouting pressure on the side wall 5 of the foundation pit during grouting.

4. Quickly design and construct grouting drilling. Form the drilling construction conditions on the ground of the side wall where the water gushing point 4 is located as soon as possible, and design the grouting drilling. Generally, two rows of grouting boreholes are designed around the gushing point 4 . The first row of drilling holes should be as close as possible to the side wall 5 of the foundation pit, and the distance b1 between the hole position line ₃ and the side wall 5 of the foundation pit should not exceed 1.5m; Drill holes in the first row, outwards according to the order and so on. The depth of grouting in the first row of boreholes is the deepest, and the grouting grouting in the first row of drillholes is at the lowest position and covers the water gushing point 4 completely. The position of the second row of drilling slurry diffusion and reinforcement bodies 14 is higher than that of the first row of drilling slurry diffusion grouting and water blocking reinforcement bodies 13 . Row by row outward and so on, a stepped weir type grout diffusion grouting water blocking reinforcement body 15 is formed. The elevation of the upper edge of the stepped weir type grout diffusion grouting water blocking reinforced body 15 will exceed or be close to the elevation of the perennial diving water level line 12 at this place. When the level 15 of the stepped weir-type grout diffusion grouting grouting reinforcement body formed by two rows of boreholes is less than the level 12 of the perennial diving water level, the number of rows of boreholes can be increased.

Grouting drilling is divided into two types: grouting water blocking drilling and grouting reinforcement drilling.

5. Grouting and water blocking drilling construction. The grouting water blocking borehole 6 is a key hole, which is 1 to 3 boreholes of the first row closest to the water gushing point 4, wherein the first grouting water blocking borehole 6 will be constructed at 4 places of the water gushing point. Each grouting water plugging drilling hole is constructed in 6 parts, upper and lower parts. The upper part is the large-diameter drilling, and the lower part is the self-advancing construction drilling of the grouting pipe. The depth of the large-diameter drilling is generally about 3m shallower than that of the self-advancing construction of the grouting pipe.

(1) Large-diameter drilling construction. The construction depth of the thick-diameter borehole is generally near the depth of the water gushing point 4 . The drilling diameter is between 110-150mm. When the construction depth of the thick-diameter drilling is close to the water gushing point 4, it is necessary to closely observe whether there is a phenomenon of drill drop (that is, the sudden drop of the drill pipe). The drill should be raised immediately, and a thick-diameter steel pipe with a diameter of not less than 108mm should be quickly lowered into the thick-diameter borehole. Lower the thick-diameter steel pipe to 2m above the cavity. Fill the cavity by injecting hard aggregates such as stones and sand or soft aggregates such as kelp into the cavity through thick-diameter steel pipes. When filling the cavity, the drill bit should be lowered into the cavity and rotated continuously to stir. In the process of aggregate filling and non-stop rotation and stirring of the drill pipe, the early-strength, anti-dispersion and quick-setting slurry with an initial setting time of not less than 3 minutes is injected through the hole in the drill pipe to cement the injected aggregate, or the injection density is different. Thick one-fluid cement slurry less than 1.7g/cm ³ .

If the thick-diameter borehole does not reveal a cavity at the depth of the water gushing point 4, the drill should also be lifted, and the construction of the thick-diameter borehole should be stopped. Not under thick diameter steel pipe.

In the construction of large-diameter drilling, the construction speed should be fast because it needs to go through the loose ground, and thick cement slurry with a density of not less than 1.60g/cm ³ with sawdust should be used as the flushing fluid to protect the wall. When a collapsed formation is encountered, double liquid slurry should be injected for consolidation. After the aggregate fills the cavity and injects the slurry, the water gushing velocity at the water gushing point will be weakened and the water volume will be reduced.

(2) Self-advancing drilling construction of grouting pipe. A drill bit is installed on the 42mm steel pipe, and the 42mm steel pipe is used as the drill rod to drill into the formation below the large-diameter borehole, and the drilling depth is about 2m below the water gushing point 4 depth. Before the 42mm steel pipe is lowered into a large-diameter drill hole and used as a drill pipe, it needs to cut the eyelet and install the expansion plug. Cut eyelets on the side wall of the 42mm steel pipe within a length of 4m above the bottom end (because the grouting interval in the stratum is designed to be 4m), the diameter of the eyelets is 6mm, and the eyelets should be evenly distributed. The number of eyelets is determined by the total area of the eyelets It is determined that the total area of the flower eye is close to the total area of the inner diameter of the grouting pipe; the expansion stopper is installed on the 42mm steel pipe, and the lower edge of the stopper should be located in the large-diameter borehole or 4.5m above the bottom port of the steel pipe. After the 42mm steel pipe is used as the drill pipe to drill to the design depth, the steel pipe is no longer proposed and used as a grouting pipe. The grouting pipe is used to inject early-strength anti-dispersion quick-setting grout into the formation, and the initial setting time of the grout is generally not longer than 50s.

The other two grouting water blocking boreholes on both sides of the rapid construction water gushing point have the same technical requirements as above, and the effect is to supplement the first grouting water blocking borehole. The spacing a1 between the _three holes is 2m. The distance b1 between the three holes and the side wall ₅ of the foundation pit is 1.5m.

6. Construction grouting reinforcement drilling. Except the grouting water plugging borehole 6, other boreholes are all grouting reinforcement boreholes. The aperture structure and the construction technology of the grouting reinforcement borehole are consistent with the grouting water blocking borehole 6 . The difference is that the injected slurry is high-concentration single-liquid cement slurry and early-strength quick-setting slurry whose initial setting time is not longer than 50s. The two slurries are alternately and continuously injected. The purpose of injecting single-liquid cement slurry is to use its strong consolidation strength to strengthen the formation and improve the overall strength of the strengthened formation; the purpose of alternately injecting early-strength quick-setting grout is not only to control the diffusion range of the slurry itself, but also to make it Remain within the designed diffusion range. The consolidated body formed after rapid solidification can also be used to intercept and block the diffusion of the subsequently injected single liquid slurry to the distal end, so that it remains at the proximal end of the borehole. This achieves the purpose of controlling grouting.

The row spacing b ₂ of the first row of grouting reinforcement drilling holes and the second row of grouting reinforcement drilling holes is 1.2m; the spacing a ₁ of adjacent drilling holes in the same row is 2m; the grouting reinforcement section of the two rows of drilling holes The length h ₂ is the same, both are 4m; the first row of drilling grout diffusion grouting reinforcement body 13, the second row of drilling grout diffusion grouting reinforcement body 14, the overlapping height h ₃ is 0.5-1m; the designed single hole grouting diffusion The diameter d ₁ is 1.5m. The overlapping width d2 _on the horizontal plane of adjacent reinforcements is 1m.

7. Grouting requirements. Before grouting, a single-liquid cement slurry should be injected through the grouting pipe, and a grouting test should be carried out. Through the grouting test, the degree of grouting of the single-liquid grout from the drain pipe 8 and the initial pressure of grouting should be observed, and the early strength and anti-dispersion of the injection should be determined accordingly. Initial setting time and final grouting pressure of quick-setting grout.

When injecting the early-strength anti-dispersion quick-setting grout in the grouting water blocking borehole 6, slowly close the valve of the drain pipe 8. Create conditions for the retention of quick-setting slurry in the formation. Once it is found that the valve is closed to a certain degree, when the drain pipe 8 has a tendency to be ejected or water seepage occurs above the foundation pit side wall 5 above the water gushing point 4, stop closing the valve and still retain the draining state. At this time, the initial setting time of the early-strength anti-dispersion quick-setting grout should be shortened, and the low pressure should be kept for continuous grouting. After grouting continues for a period of time, you can still try to continue closing the valve until the valve is safely closed. After the valve is closed, the grouting continues until the grouting pressure reaches the design final pressure. The design final pressure is generally the maximum safe pressure that does not cause cracking and swelling of the 5 supports on the side wall of the foundation pit. In the example, the final pressure controlled by grouting water blocking drilling is 0.5MPa, and the control of grouting reinforcement drilling is 0.5 MPa. The maximum final pressure is 1.5MPa.

Example 2:

On April 5, 2017, during the construction of the foundation pit of Hengdacheng Station of Jinan Metro Line ^R3 , water gushed out suddenly at a depth of 13m from the ground surface on the south side wall of the foundation pit. According to the measurement, the water volume is 37m ³ /h, and the water volume has not changed after 6 hours of observation. The water quality is black and contains silt, and the silt content is about 10-15%. Based on the analysis of the survey data, the possibility that the water source is the confined water in the gravel layer at a depth of 17m below the surface has been ruled out. After testing the water quality, the water quality was the same as that of the underground diving water, and the possibility of pipeline leakage was also ruled out. After investigation, it was found that the water source was the water in the ancient river channel buried underground, and the possibility that the supplementary water source was the water in the channel about 300m to the west of the foundation pit could not be ruled out.

The treatment plan adopted is to insert two 108mm steel pipes at the water gushing point, and use the steel pipes to draw the water out. A valve is installed at the end of the steel pipe. The outer side of the steel pipe and the pit wall are plugged with sandbags, and the outer side is closed with C20 early-strength concrete. After trying to close the valve, the water level rose to a height of 2.5m in 2 minutes, gushing out from the sprayed protection body of the initial support of the foundation pit in the form of multiple strands. It shows that the ability of the side wall of the foundation pit to resist water pressure is small, and the ability to resist grouting pressure is also small. If the conventional grouting anchor is used to grout around the water gushing point on the side wall of the foundation pit, it will be difficult to control the rise or spread of the water level, which will affect the safety of the side wall of the foundation pit above the water gushing point and affect the safety of the side wall of the foundation pit. threatening.

Finally, sandbags are piled up around the water gushing point for back pressure. A vertical borehole is constructed on the ground outside the edge of the foundation pit above the water gushing point. The lower mold pocket in the borehole isolates the upper rock and soil. The position of the mold pocket is about 10m. Dispersed quick-setting slurry (C-GT slurry). After the grouting started, the grout ran seriously and the water was reduced, and the water inflow returned to the original water volume, and the water volume repeated. During the grouting process, by adjusting the grout ratio parameters, the initial setting time of the grout can be reduced, the grout running out can be controlled, and the valves can be gradually closed. Through 3 drill holes, the gushing water was successfully blocked. Afterwards, 6 boreholes were constructed to strengthen the strata around the water gushing point by grouting. The grouting reinforcement grout was C-S grout and single liquid cement grout, and the final grouting pressure was 1.5MPa.

Finally, it should be noted that the above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, it is still The technical solutions described in the foregoing embodiments may be modified, or part of them may be equivalently replaced. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention. Although the specific implementation of the present invention has been described above, it is not a limitation to the protection scope of the present invention. Those skilled in the art should understand that on the basis of the technical solution of the present invention, those skilled in the art can do it without creative work. Various modifications or deformations are still within the protection scope of the present invention.

Claims (7)

1. formula safe grouting construction method in step heap weir in a kind of stratum for blocking the larger water burst of deep-foundation side wall, feature exist In, comprising:

Water yield and quantity of sand and mud to foundation pit deep side wall are observed, are calculated；

Tapping pipe is arranged in issue to sluice；

Back-pressure body is set around issue, back-pressure is formed to the foundation pit side-wall around issue；

It is drilling on the ground of side wall where issue, drilling is at least divided into two rows, the depth of the first row hole drilling and the second row hole drilling Degree is in up/down steps formula, is the first row hole drilling by proximal wall prop, is successively reduced according to sequence, drilling depth outward；

Slip casting blocks；

The first row bored grouting depth is most deep, and slurries diffusion reinforcing area is in extreme lower position and water burst is completely covered Point；

Second row hole drilling slurries diffusion reinforcing area position is higher than first row slurries diffusion reinforcing area；

The block water upper limb absolute altitude of reinforcing body of last row hole drilling slurries diffusion will be more than or close to the long-term phreatic table at this.

2. the method as described in claim 1, which is characterized in that the drilling is divided into grouting for water blocking drilling and grouting and reinforcing drilling Two kinds.

3. method according to claim 2, which is characterized in that the grouting for water blocking drilling is the first row near issue 1~3 drilling, wherein first crucial drilling is wanted to construct at face issue.

4. method according to claim 2, which is characterized in that the grouting for water blocking drilling, which is divided into the top part and the bottom part, gives work, and first Part is that particle size drills, and second part is Grouting Pipe self-advancing type construction drill.

5. the method as described in claim 1, which is characterized in that the distance of the hole location linear distance side wall of first row hole drilling is not More than 1.5m.

6. the method as described in claim 2-4 any one, which is characterized in that inject morning Qiang Kangfen in grouting for water blocking drills When dissipating rapid hardening slurries, slowly closing sluicing tube valve；Once tapping pipe, which has, to be ejected it was found that valve is closed to a certain extent When occurring infiltration phenomenon above trend or foundation pit side-wall issue, phase down valve still retains sluicing state；To shorten at this time In the presetting period of early strong anti-dispersion rapid hardening slurries, low pressure is kept to continue slip casting；After slip casting continues for some time, can still try after It is continuous to close valve, until valve is by safety shutdown.

7. the method as described in claim 1, which is characterized in that after closing sluicing tube valve, Yao Chixu slip casting, until slip casting pressure Until power reaches design final pressure；Design final pressure is the Maximum safe pressure for not causing foundation pit side-wall prop cracking, bulging occur.